Bibliographic references
Popov V. V., Sorokin F. D., Ivannikov V. V. Finite element of a flexible rod with separate storage of accumulated and additional rotations for the problems of nonlinear dynamics of aerial vehicles structures. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/8cf/Popov_Sorokin_Ivannikov_rus.pdf Dynamical behavior of various aircraft parts, such as wing spars, fuselage stringers, propeller blades etc. [1–4], can be accurately described by a flexible rod model, as though these structures may undergo large displacements and rotations, while their strains remain small. A large set of numerical techniques is available for flexible rods dynamics analysis. However, FEM is the most appropriate in the present context.
A number of finite elements has been developed for solving flexible rods nonlinear dynamics problem. Reference [5] is one of the pioneering work in this area. Treating a rod as a three dimensional body, which dimensions and kinematics are specifically constrained, the author proposes a powerful model, where both displacements and strains can be arbitrarily large. This contribution gave rise to an entire family of the so-called geometrically exact approaches for statics and dynamics analysis of flexible beams [6, 7].
Another popular alternative to constructing geometrically nonlinear beam models is the so-called corotational approach [8]. A simple corotational finite element based on the small strain hypothesis was proposed in [9]. Being quite simple to derive and implement, this model suffers fr om a serious issue, namely, the total Lagrangian formulation is chosen for storing both displacements and rotations. For the latter, it leads to numerical problems when approaching the rotation angle of 2π value. The model from [10], which in fact combines the two aforementioned fundamental approaches, eliminates this limitation introducing the updated reference configuration, though the underlying math is much more complicated as nonlinear elasticity theory is applied. The similar incremental description of rotations is also used in [11] in the context of constructing a specific rod finite element adapted for multi-body dynamics problems. However, the obtained tangent stiffness matrix revealed to be non-symmetric even for the simple conservative loading cases. This, obviously, restricts the selection of linear solvers to be used in association with this model, and, thus, compromises the overall performance of the numerical solution.
The Absolute Nodal Coordinates [12, 13] formulation is another reliable technique for building nonlinear rod finite elements based on the choice of high order interpolation functions for the rod geometry and deformation description.
The majority of existing approaches (along with the currently presented) employ the Euler vector for rotations description. But alternative quantities, such as the Rodrigues vector [14], can be introduced as well. A particular attention to exact conservation of momentum and total energy is given in this article. This aspect was carefully studied also in [15] in the context of nonlinear of rods dynamics.
The present contribution is the continuation of the authors’ previous work [16], wh ere a flexible rod finite element for static analysis has been proposed. The nonlinear rod FE, which large motion kinematics is based on the updated Lagrangian formulation for the rotations increments, is currently adapted for transient dynamics problems. The rotations data is separated into two parts. The accumulated rotation is stored as the rotation matrix, while the incremental part is described by the Euler vector [17]. Unlike the existing approaches, the design of the developed element is beyond the scope of the well-known stiffness and mass matrices of the conventional rod FE that significantly simplifies the derivations. This allows embed practically any linear rod model, whether it is of Timoshenko or Euler-Bernoulli type.
The article presents the closed-form expressions for the element generalized mass and gyroscopic matrices, and for the right hand side inertia loads vector. Owing to the underlying update Lagrangian formulation for rotations description, the proposed element does not exhibit any numerical instability related issues for any rotation magnitudes during the structure evolution. Besides, as the total rotation matrix is updated after each Newton-Raphson iteration [18], nearly quadratic convergence has been achieved.
To demonstrate the element workability and robustness two numerical examples were analyzed. The results were compared with the existing reference data [19, 20, 21] and with the third party FEM packages.
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Marchukov E. Y., Kulalaev V. V., Vovk M. Y. Calculation method for dynamic target destruction by laser beam within the specified range. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/79d/Marchukov_Kulalaev_Vovk_rus.pdf The near and far space exploration is impossible without creating modern technologies of constructional assembly welding employing laser radiation when the structural surface can be considered as a conditional target. At the same time, the calculation method development of laser beam thermal effect is one of prior scientific tasks, which solution is obtained in this paper based on the variation method [1-20]. The advantage of the variation method [1-3] consists in the possibility of solving nonlinear problems of the heat and mass transfer when the coefficient of thermal conductivity is a tensor quantity in non-isotropic mediums [3-8]. Such situation is implemented completely at impact of the powerful laser beam on physical environments of various targets while their destruction at a specified variable range. In these initial conditions of thermal impact of the powerful laser beam the thermal problem solution of target environment destruction using the variation method [4, 7] becomes significantly simpler. In this case the solution is reduced to searching some function, describing the formation of caverne mobile walls with some temperature gradient on the surface of liquid-alloy. The solution of the specified task herewith is performed for the benefit of the wide class of various industrial technological processes, including technologies of near and far space exploration.
The presented method is based on the solution of the non-stationary problem of the powerful laser beam installed on the mobile platform effect on the dynamic target firm surface – the structure for variable range. The thermal spot sizes are determined by the output aperture of the focusing laser optics. Under the impact of thermal gradients on the target surface depending on time of laser beam influence the mobile borders destruction of the target body occurs in the form of a melting cavern and material boiling. If the conditional target represents the sheet of metal with the specified thickness, the formed cavern can form through smelting rate of metal that is not admissible. The cavern borders movement is described in the paper as the corresponding mathematical model of an unknown quasi-stationary temperature field formation, which is formed by large concentration of heat energy on the limited area of the thermal spot at the set influence period. The application example of the cavern formation calculation method in industrial laser welding processes is given.
The results of this work can be employed for the benefit of creating and optimizing industrial technological processes of temperature processing, various materials cutting and welding by laser machines in different physical environments. | ||
Morozov D. V., Chermoshentsev S. F. Fault localization model in the unmanned aerial vehicle control system equipment employing a flexible in-flight functioning algorithm. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/7e6/Morozov_CHermoshentsev_rus.pdf The authors developed a model of fault localization of the onboard test and control equipment of the unmanned aerial vehicle control system while its self-control. The model is represented in a graph form. The graph is a polytochomic decision tree. The graph vertices reflect the functional composition of combinatorial subsets of elements (KPI) in elementary self-tests, in controlled and suspicious situations, PDA and efficiency. KPIs and their taken decisions are based on the results of inspections and the functional KPI membership. Arcs are the probability of the states and events transition. Such graph structure allows solve the problems associated with carrying out the appropriate self-calibration (ES), in case of failure localization in the on-board control-checking equipment.
Expressions for the false rejection probability and the on-board checkout equipment false failure detection probability are obtained. They allow solve the problem of determining the optimum depth of failure localization, with account for elementary self-tests intersection and applying a flexible operation algorithm in-flight, and solve the final task of intended application. The analytical equations obtained in general form for the corresponding decisions account for states of functional components, such as on-board checkout equipment, self-monitoring systems, the fault suspected area of elements, the controlled area of the elements, and the controlled area of the elements changing process.
While the next elementary self-test performing employing a mathematical model, a loss matrix is constructed, and the false rejection of the remaining elementary self-tests from the suspected region of elements is estimated. As a loss we consider the probability of false rejection by the onboard control and checking equipment of an unmanned aerial vehicle by the elementary self-test performed, selected from the elementary self-tests area, covering the suspected fault region of elements combinatorial subsets. | ||
Pokrovskiy A. N., Dadashov C. M. Some specifics of Blasius problem solutions. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/3d4/Pokrovskiy_Dadashov_rus.pdf The presented work performed numerical study of solutions behavior of laminar incompressible boundary layer on a flat plate (Blasiumo problem). It is common knowledge that Blasius proposed a statement of the problem as applied to a flat plate, except for the leading and trailing edges, allowing obtain the plate resistance with an adequate degree of accuracy. In this article, the authors outline four typical types of plates to refine the statement of the problem, and eliminate some inaccuracies being assumed in the previous statements of the problem.
In this paper, the authors conclude that new advanced methods serve the purposes of ensuring an aircraft optimal design and upgrading its performance characteristics. To this effect, it is necessary to improve conventional and develop new methods for aerodynamic characteristics computing with improved accuracy by accounting for viscous effects significantly affecting the aircraft characteristics and dynamics of its motion.
The authors tackle such issues, as a plate’s nose meltback commencing at supersonic flight speeds due to the impossibility of removing of large heat quantity, released in a flow, through the plate nose. In this respect, the authors analyze the succession of the problem statement on triangle strip flow-around by a supersonic airflow, from an idealized infinitely small to really blunted one.
Four approaches to employing various models for the problem solution on resistance of the plates and blunted wedge were examined. Two characteristic plates’ types, namely geometric and physical, are examined.
A method for computing resistance of the plates and blunted wedge, applying programs, was proposed. To compute the plate resistance, the authors show the necessity to compute the friction coefficient with LAYER-2 program, as well as resistance of the cylinder contamination and bottom pressure. C_{x}_{pl} is computed for both laminar and turbulent layers with account for the friction resistance coefficient C_{xfr} , coefficient of cylinder blunting resistance C_{xbl} and bottom pressure coefficient C_{xbot} :
Сx_{pl }= Cx_{fr }+ Cx_{bl }+ Cx_{bot} _{}
_{}
In conclusion, it is noted that LAYER-2 program application enabled computing resistance of these plates with improved accuracy, including all components of total resistance:
Сw_{клина}_{ }= Cx_{зат}_{ }+ Cx_{тр}_{ }+ Cx_{дон} + Cx_{клина} _{}
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Konyukhov I. K. Analysis of “flying wing” scheme application at unmanned aerial vehicles of “air-to-surface” class. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/474/Konyukhov_rus.pdf The article describes some ways and hardships of a “flying wing” scheme application while developing long-range cruise missiles of “air-to-surface” class. Advantages and disadvantages of “flying wing” arrangementh and history of its development are briefly touched. An attempt to classify the “flying wing” type in applications to the particular structures of aircraft was made. A number of problems, occurred while these aerial vehicles development, were described. One of them is еру wing parameters selection (airfoil type, warps, sweep angle etc.) to ensure maximum aerodynamic quality over the whole flight path. This problem is not simple due to the low wing loading, specific to the arrangement under discussion, which is not optimal at low flight altitudes required for effective overcoming the enemy air defenses. Another crucial problem is an internal arrangement of wing-hull since it does not fully fit for locating all necessary elements of an aerial vehicle, such, in the first place, as the power plant, warhead and large-size radio-electronic devices. The presented work focuses mainly at the cruise missiles of a “flying wing” type allocation in the internal bays of a carrier (external arrangement). Several design options of the exterior, capable of solving this problem, were highlighted. They are as follows: accommodation by stack across the weapon bay, the wing folding, and a concept with the developed center wing-hull. Merits and demerits of these options were considered. Height-to-width aspect ratios of the weapon bay necessary for the most effective allocation of a cruise missile of the “flying wing” type was studied. These ratios differ greatly from those of attack aircraft of the traditional arrangement, but they fit perfectly the arrangement inside the next generation strategic bombers (B-21, PAK DA, H-20) under development at present. | ||
Krutov A. A., Pigusov E. A., Chernavskih Y. N., Chernousov V. I. Conceptual design of next generation heavy transport aircraft. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/dad/Krutov_Pigusov_CHernavskikh_CHernousov_rus.pdf The lion share of Russian transport aviation profits accrues to transportation of oversized and heavy cargoes by wharf aircraft An-124 and Il-76. The significant share of these cargoes accrues to An-124 due to its higher weight-lift ability and the size of the cargo cabin. The intensive exploitation of An-124 aircraft by the Aerospace Forces of the Russian Federation and civil air cargo carriage will eventually lead to the airframe service life wear-out (even with account for its prolongation). At the same time, the An-124 production recommencement is impossible due to the current geopolitical situation. It is also worth mentioning, that An-124 effectiveness while containers and pallets transportation (constituting the biggest part of freight traffics) is rather low compared to cargo modifications of wide-body passenger aircraft
Thus, there are prerequisites for developing new heavy transport aircraft employing modern achievements in the field of design, aero dynamics, strength, material science, control systems etc.
The perspective heavy transport aircraft should become the adequate replacement of An-214 for Russian military transport aviation, and, at the same time, be attractive to civil cargo airlines, i.e. possess the economy of General cargos transportation, comparable to cargo modifications of passenger aircraft.
The technical concept of the prospective heavy transport aircraft “Elephant” (HTA “Elephant”) meant for carry the wide range of cargoes, including heavy and oversized cargoes, was developed within the framework of Government Contract with the Ministry of Industry and Trade of the Russian Federation in Central Aero-hydrodynamic Institute.
Selection of the major parameters of the aircraft was performed. The draft aerodynamic characteristics and weight reports of the developed arrangement options were determined. Computation of HTA “Elephant” performance and take-off and landing characteristics was performed. The selected geometry and weight parameters ensure transportation of 150 tons of payload at a distance of 7000 km with basing on a runway 3000 m long. With maximum payload of 180 tons, the practical flight range is 4900 km. The takeoff weight limitations while basing on a runway 2500 m long are also determined.
The obtained results will be applied as a ground for the studies continuation of a prospective heavy transport aircraft. | ||
Bagrov A. V., Dmitriev A. O., Leonov V. A., Mitkin A. S., Moscatinev I. V., Sysoev V. K., Shirshakov A. E. Global Lunar optical navigation system. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/cce/Bagrov_Dmitriev_Leonov_Mitkin_Moskatinev_dr.pdf The lunar surface exploration and the future construction of lunar bases should be based on a high-precision objects positioning system on the Moon, such as lunar-ships and manned vehicles. The similar-by-purpose global positioning systems operate successfully on the Earth, allowing users to determine their position anytime with an accuracy less than 5 meters. The wish to replicate the worked-out global positioning system also on the Moon seems quite natural.
Being the full analogue of the Earth version of the global satellite positioning system, the lunar global positioning system is rather very complex and expensive. It stems from the fact that operation of the whole system consisting of 8 to 18 spacecraft is required to serve even one customer.
The goal of the work consists in developing a lunar navigation system based on new principles. Such a system can be created based on optical-electronic surveillance systems and light laser beacons.
An optical navigation system including lunar reference points, a SPACECRAFT at the Lagrange point and an auxiliary SPACECRAFT on the lunar is to be developed.
This goal achieving is realized due to the main components, including the scientific novelty of the project:
The objects global positioning system on the Moon surface, employing the frame selenocentric coordinate system, can provide measurements in real time, if the optional azimuth tool is placed in the libration points. | ||
Remshev E. Y., Danilin G. A., Titov A. V., Ermolenkov P. A. Ensuring technological and performance characteristics of products from titanium alloys by method of acoustical emission. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/274/Remshev_Danilin_Titov_Ermolenkov_rus.pdf The article analyses the possibility of employing a method of acoustical emission for revealing external and internal defects in metal parts, and predicting relaxational properties of mechanisms’ elastic elements while static, dynamic and cyclic loading in the course of long-term operation.
Method of acoustic emission (AE) is the most promising non-destructive method for disk spring quality control. It allows detecting various defects in the products under the workload and predict stability (or instability) of performance indicators, including propensity to relaxation.
Elastic elements and springs of different purpose are widely used in various mechanisms, such as shock absorbers, energy storage devices and actuators, operating under complex cyclic conditions under dynamic and conditionally static loading. The VT23 titanium alloy microstructure evaluation criteria based on the level of acoustic emission signals were established either.
The regularities of acoustic emission signals level changing depending on the defects presence and development, relaxational withstandability and microstructure of disk springs made of spring steel and titanium alloy at the stage of their fabrication and pre-operational testing were established based on the experimental studies. The VT23 titanium alloy microstructure evaluation criteria based on the level of acoustic emission signals were established as well.
Two-factor mathematical prediction model for relaxation disk springs (made of 60S2A steel or VT23 titanium alloy) stability prediction depending on the level of acoustic emission signals level at the stage of gripping in the course of long-term operation was constructed.
Recommendations on practical application of the research findings were developed, and scientifically substantiated method for disk springs of steel and titanium alloys relaxational strength predicting was designed based on the established regularities. | ||
Bogdanovich A. B., Polyakov V. A., Volkov E. N. The study of hydraulic characteristics of a model gel-like substance based on carbohydrates. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/4d4/Bogdanovich_Polyakov_Volkov_rus-.pdf In this article, an experimental study of the flow of a model gel-like substance consisting of hydrocarbons is carried out. The gel-like substance is used in the supply systems of advanced aircraft. The main task of the study is obtaining dependence volumetric flow rate of the model gel-like substance fr om a supply pressure and a temperature.
The dynamic viscosity of the model gel-like substance is 100 Pa·s at the temperature of + 5ºС.
The main equipments for an experiment are a displacement device of piston-type and a universal testing machine. Experiments were carried out with the model gel-like substance in the temperature range of + 3ºС... + 35ºС.
The graphs of the dependence volumetric flow rate of the gel-like substance from the supply pressure were based on the experimental data obtained.
Empirical dependences of the volumetric flow rate on the supply pressure and the temperature of the model gel-like substance were obtained.
The volumetric flow rate of the model gel-like substance is described by a power-law:
Q_{D} = k_{T }⋅ µ ⋅ F_{nz} ⋅ (ρ_{D}/98066,5)^{n}, wh ere k_{Т }= f (T_{Н}) – is an empirical coefficient that takes into account the dependence of the viscosity of the model gel-like substance on the temperature, m / s;
m – a consumption coefficient of the throttle, –;
F_{nz} – a minimum area of an orifice throttle, m^{2};
p_{D} – the supply pressure, Pa;
n – an exponent, –.
As a result of the work methodological approach was proposed and a methodology for the calculation and experimental determination of the flow characteristics of the model gel-like substance that imitate the viscosity and a composition of gel-like fuels was developed. The error in determining flow characteristics of gel-like substances does not exceed 1%.
Empirical dependences of the volumetric flow rate from the supply pressure for the model gel-like substance were defined in the temperature range from + 3ºС to + 35ºС and the supply pressure from 0.02 MPa to 6 MPa. A discrepancy of experimental and empirical dependences is not higher than 6%.
The dependence of the volumetric flow rate on the supply pressure is a power-law. The nature of equation changes depending on the viscosity of the substance. | ||
Ezrokhi Y. A., Drygin A. S., Kizeev I. S., Selivanov O. D., Fokin D. B. Prospects of a three-flow technology application in conditions of supersonic flight. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/e15/Ezrokhi_Drygin_Kizeev_Selivanov_Fokin_rus.pdf The article presents the results of the third loop application possibility estimating to enhance the engine and power plant characteristics in the range of the large supersonic flight speeds. The authors consider various possible options of three-flow turbojet engine schemes with combustion chamber, as well as tackle the issues of the third loop control.
In the course of this work, a new critical unit of the three-flow turbojet engine was revealed. This is a three-flow mixer. The coefficient of total pressure additional losses while mixing was computed for one of its possible designs.
Computations of the two-flow turbojet engine with afterburner with take-off thrust of 98 kN, assumed as a basic, and its possible modification, employing the third loop technology, were performed. Due to the additional losses while mixing significant effect on the characteristics being obtained, computations of a three-flow turbojet engine were performed with the values of the above said losses of 0 and 7%.
Comparative evaluations of characteristics of power plants options with the two-flow and three-flow turbojet engines as parts of a supersonic aircraft were performed. The aircraft take-off weight variation was accounted for in association with the engine weight increase while the rest components remained the same. While meeting the requirements to the equal take-off thrust-to-weight ratio, the computations with various additional losses level in the combustion chamber were performed.
The obtained results demonstrate that application of the third contour technology with all three contours’ streams mixing prior to the combustion chamber potentially allows increase the engine thrust in flight modes with large supersonic speeds (М = 2,2–2,8) and, accordingly, the maximum altitude (ceiling) and flight speed, thereby considerably expand an application range of the gas turbine engine. | ||
Moung H. O., Kyaw Z. L., Prihod'ko S. J. Developing an algorithm for aerodynamic coefficients identification accuracy increase based on harmonic input signals. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/cdd/Moung-KHtang-Om_CHzho-Zin-Latt_Prikhodko_rus.pdf The presented article deals with the problem of algorithm for aircraft aerodynamic coefficients accuracy increase on flight experiments data. All the signals employed while coefficients identification contain measurement noises, approximated by normally distributed random values with zero average and specified dispersions. A method of harmonic signals decomposition was considered to improve the identification accuracy.
As a rule, the flight modes, when control signals are being set by the pilot, are employed for identification. It is evident, that the high-accuracy reproduction of the signal wwaveform is impossible with manual control. Thus, the precise a priori knowledge of a test signal in this case is impossible, which determines the strong dependence from measuring errors. Therefore, the authors suggest apply a hardware-generated test signal, such as combination of two sine waves with different frequencies. For linear object, such double-frequency signal creates responses at the same two frequencies. Since we know now the exact shapes of the input and output signals, we can represent them as a composition of the four linearly independent harmonic components. The multiple regression method should be applied to obtain the coefficients. In this case it is highly efficient since reference harmonics are precisely known. Thus,
Thus, the basic regression analysis requirements are fulfilled, ensuring unbiased estimates of coefficients in the presence of the object signals’ measurement noise. Further, employing the decomposition coefficients, we reconstruct the signals, which are now to a high degree free from noise.
The article presents the results, demonstrating the high accuracy of coefficients identification at high levels of measurement noise. | ||
Borisov A. E., Leont'ev V. A., Rubinshteyn M. A., Rusakov I. V. The new TsAGI research helicopter simulator VPS-5 . Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/7e6/Borisov_Leontev_Rubinshteyn_Rusakov_rus.pdf This article describes briefly the new research helicopter simulator at TsAGI intended to conducting researches in helicopter flight dynamics. The simulator uses the helicopter flight dynamics model developed in TsAGI and has several significant features distinct from that of other research simulators in Russia.
Its 8-channel projective visualizing system has semi-spherical screen up with viewing angles up to 200 degrees along horizon, 50 degrees above horizon and 60 degrees below the horizon with side view. The latter is very important to research take-off and landing operations from small area surfaces.
The simulator has fixed one-seat pilot cabin with interactive displays imitating cabin gauges and indicators, and realistic pilot controls identical to controls of civil helicopter Mi-8.
The Moog’s 4-channel digital electro-mechanic control loading system (CLS) is attached to cyclic pitch stick, collective pitch stick and pedals. Characteristics of CLS can be adjusted either by reconfiguring the generic software application model or by developing new software application model using development libraries and environment integrated with Matlab/Simulink. CLS allows the simulator to be reconfigured to different kind of helicopter flight control systems.
The simulator is equipped with software applications that broaden the research area. ‘MFD Editor’ application allows creation of virtual indicators and control panels. ‘Local weather’ application allows to model in simulator’s world both standing and moving atmospheric areas with local weather peculiarities. There is a wide library of standing and moving virtual objects such as buildings, offshore platforms, ships allowing research of marine flight operations. The simulator can be combined with another helicopter flight simulator in TsAGI in the single virtual world.
The advanced features of new helicopter simulator allow researching a wider range of flight dynamics issues of existing and developing helicopters. | ||
Vereshchikov D. V., Voloshin V. A., Ivashkov S. S., Vasil'ev D. V. Applying fuzzy logic for developing simulation model of pilot's control actions. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/ea6/Vereshchikov_Voloshin_Ivashkov_Vasilev_rus.pdf Wide application of mathematical and in-line simulation modelling became vital and almost uncontested method of modern aircraft developing and trial. It allows reduce the amount of test flights and increase the informativity of conditions, as well as reduce degree of risk of flight experiment. Thus, one of primal problems is security of the obtained results adequacy. Adequacy of the simulation modelling results is ensured by application of Authentic mathematical models of aerial vehicles and Participation of the pilot-operator, as a obligatory link in the system “Pilot-Control system-aircraft” with its intrinsic behavior. However, the problems occur when it becomes necessary to perform a set of a target problem modelling of piloting to obtain statistically authentic results. As a result, the statistical data obtaining becomes a rather labor-consuming problem, requiring considerable amount of resources and time. Solution of this problem consists in developing authentic “pilot-operator” model.
At present, many works on creation of models of the pilot’s operations with subsequent simulation modelling are fulfilled. With up-to-date approaches to such models development it is possible to refer to:
− quasilinear models;
− theory of fuzzy sets and fuzzy logic;
− artificial neural webs;
− genetic algorithms.
Any quasi-linear model is understood as a model in which the relation between the input and output signals retains linear properties. Such model allows solving only single-loop single-channel problem. Thus, it is successfully employed, mainly, for the analysis of control systems. However, in real flight the pilot solves a multiple-loop multi-channel problem, and his responses to an input perturbing signal are of non-linear character, and, besides, apart from a linear component, “trail” component is also present among the pilot’s operations. Thus, the quasi-linear model is not capable to describe precisely enough the character of pilot’s operations, and it can be employed only for a narrow circle of problems. Artificial neural websnetworks and genetic algorithms are devoid of these shortages. However, in turn, they are complicated enough in the realization. | ||
Mironenko V. V., Matsuro E. A. To the question of optimization and design of parts, produced by cavity elastic forming, with the use of reconstruction. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/cd9/Mironenko_Matsuro_rus.pdf Using the example of a classic shape for a box-type part, optimization of the cavity elastic forming process using a cover with guaranteed clearance is considered, as well as classical optimization of a part based on modeling and optimization based on the technology of “technological reconstruction”. Schemes of classical cavity elastic forming process and cavity elastic forming process with guaranteed clearance are presented. The main aspects of using NURBS technology for restoring the shape of a part fr om a finite element mesh are described. The problems arising in the case of classical optimization using simulation and the ways of their solution using “technological reconstruction” are shown. The results of calculation in the form of gradients are presented: plastic deformations; thickness and quality zones based on the Keller-Goodwin lim it strain curve.
The purpose of the article is to improve the existing technological process for the production of “box” parts, which relate to sheet metal forming production. The following problems are solved in the article:
– replacement is not a progressive and non-stable method of shaping, to a newer method;
– elimination of local loss of stability (wrinkles) along the flange;
– elimination of thinning in radius transitions and bottom separation;
– search for the most rational technology for optimizing the geometric shape of a part in the region of radius.
As a result, the technology of “technological reconstruction” has been developed that allows rationally optimizing the shape of a part taking into account the way it is formed. The technology is versatile and it is possible to use it in various aircraft-engineering enterprises. | ||
Chernodarov A. V., Ivanov S. A. Identification of models and adaptive filtering of inertial sensors noises. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/22c/CHernodarov_Ivanov_rus.pdf This article is devoted to the problem of reliability increasing of of inertial measurement units (IMU) error estimation by an extended Kalman filter (EKF). This problem is associated with the noise models of inertial sensors and real processes inadequacy. Gyroscopes and accelerometers are considered as inertial sensors. It is known, that the models inaccuracy and other causes of methodical and instrumental character result in the EKF divergence. The EKF divergence manifests itself in the fact that the actual estimation errors considerably differ from their predicted mean square values obtained while solving the Riccati equation for the covariance matrix. It should be noted, that the actual estimation errors come to light only at the stage of mathematical simulation. In the known works the models inadequacy is compensated by the corresponding EKF parameters adjustment over the renovative sequence. This renovative sequence is the difference between actual and predicted observations. The predicted observations are formed by estimating the IMU errors. However, in real operating conditions, due to the errors of external measuring tools or lack thereof, such adjustment is not always possible. In addition, there are approaches to estimation of statistical characteristics of inertial sensors by the Allan method. This method allows estimate the stability of errors on the moving intervals of averaging. However, such approaches do not associate with the EKF parameters tuning. Thus, their application does not ensure the EKF adaptation in real operating conditions. The scientific originality of the proposed work is associated with the addition of procedures for the noise models of inertial sensors tuning to the known EKF adaptation algorithms. The authors propose to perform the adjustment of models based on structural-parametric identification by of correlation processing of the sensors error estimates. Such processing can be performed both in real time, and according to the data of onboard recording devices. The developed algorithms allow take account for the change in accuracy and dynamic characteristics of inertial sensors through the corresponding coefficients of the IMU errors. To implement the proposed identification technology, the errors of inertial sensors should be included in the estimated parameters vector. The performed studies revealed that when the EKF is included in the IMU error estimation circuit, it is necessary to perform not only the factory bench calibration of inertial sensors, but also the identification of their noise models. The article presents the results of experiments confirming the expediency of noises identifying models of inertial sensors while operation. | ||
Dyachenko S. A. Synthesized vision system model developing for perspective civil aircraft. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/a3c/Dyachenko_rus.pdf Following the increase of safety requirements for flights of modern aircrafts and significant growth of their avionics functionality a relevant task is the development and implementation in civil avionics systems a number of additional systems which could provide situational awareness of crew of rather cockpit external situation and reducing probability of a human mistake to a minimum in case of a catastrophic situation.
The technical vision systems (TVS) provide the crew with necessary information of the aircraft orientation and cockpit external situation in the visualized form convenient for the human.
Among the existing types of aviation class TVS (from the view point of integration into avionics structure) the synthetic vision system (SVS) is the most preferable due to the absence of the need to install any additional equipment on the aircraft.
SVS is the hardware and software solution based on onboard computers and flight indicators providing the real-time three-dimensional view of a cockpit external situation.
The purpose of this work consists in developing the SVS model with application according to the concept of the integrated modular avionics (IMA) for the future civil aircraft of transport category.
The following results of the SSV developing and modeling of are presented in this article:
– analysis of the existing types of aviation TVS;
– analysis of the corresponding standards requirements for development of the civil aircraft equipment imposed to SVS;
– the new SVS architecture with application of the IMA concept;
– the proposed SVS hardware structure;
– the program and algorithmic of the SVS to synthesize 3D images of the land surface topographical sites with high degree of informational content;
– the results of the proposed SVS testing, which proved its suitability for the designated tasks.
The developed SVS prototype complies with the basic documents for the development of modern civil aircrafts.
Assessment of the computing time of the developed algorithms based on series of tests with various examples of the land surface confirmed the validity of the DO-315 requirements in the part of frequency updating. | ||
Mironov A. N., Flowers K. Y., Kovalsky A. A., Palgunov V. Y. A technique for possibility and conditions vindication for specified lifespan indicators prolongation of antennae systems of a spaceport measuring complex ground stations. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/c3e/Mironov_TSvetkov_Kovalskiy_Palgunov_rus.pdf The article deals with the issues of developing a technique for possibility and conditions vindication for the specified lifespan indicators prolongation of antennae systems (AS) of a spaceport measuring complex (SMC) ground stations (GS).
The standard SMC facility is an GS containing antenna system, which, in its turn, includes mission-critical components, such as antenna rotary mechanism, mirror system (antenna array) and radio frequency equipment set. For this reason, the object of research is AS GS SMC, and the subject of research are the processes and scientific methodological vindication of the possibility and conditions for the specified lifespan indicators prolongation of AS GS SMC.
The purpose of the studies consists in developing scientific and methodical provision for vindication of the possibility and conditions for the specified lifespan indicators prolongation of AS GS SMC based on actual state with account for the limited volume of initial data on reliability of the element base and capabilities of failure recovery.
The authors performed system analysis of the approaches to assessment of technical condition and forecasting AS GS SMC residual resource, developed mathematical model of the AS GS SMC limit state achievement, and an algorithm for forecasting the AS GS SMC residual resource (service life).
The following basic methodological principles constitute the ground for the technique under development:
– Prolongation of the AS GS SMC assigned lifespan indicators should be performed within the limits of the predicted residual lifespan;
– Forecasting of the AS GS SMC residual lifespan should be performed with account for the element base reliability variation in time, and possibility of the equipment maintenance at failures;
– An acceptable fidelity of the AS GS SMC residual lifespan predictive estimate in conditions of restricted statistical data volume should be provided by the sound selection of the predictive model dimension, and employing extra expert information on the element base reliability and operability restoration capability while failures;
– In case of mismatch of the planned term and the actual AS GS SMC residual lifespan , the list of additional measures, allowing increase the actual AS GS SMC lifespan to the required values with minimum material and financial costs should be determined
Application of the scientific and methodical apparatus proposed in article will allow increase the validity of decisions on AS GS SMC operation management, and ensure their reliable and safe functioning under material and financial costs saving.
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Kuzmin R. E. Phase locked loop of satellite communication systems receiving channels. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/9f8/Kuzmin_rus.pdf The article considers the receiving channels phase synchronization method of a satellite subscriber terminal with two receiving antennas. Such a method allows us to solve the problem of raising the signal level in the subscriber system against the background of noise. For the possibility of in-phase addition of signals of two channels before demodulation, it is necessary to eliminate the phase difference between them, which arises due to the spacing of the antenna pair elements by at least a quarter of the wavelength. It guarantees the independence from noise in each of them. To eliminate the phase difference, a phase-locked loop (PLL) system of receiving channels with a quadrature modulator is employed. Such scheme is a full-fledged substitute for the phase-shifter or digital phase rotation algorithm. While working with the system model, an imitation model was constructed from two receiving channels of a satellite communication system with phase-locked auto-tuning. It is shown that the system allows increase the level of the valid output signal by implementing the PLL ring. The effect of the low-pass filter band on the system speed was studied, and the dependence of the phase error at the output from the signal-to-noise ratio was obtained. In the long term, this system can ensure the operation of both the receiving and transmitting parts of the communication module with the antenna array of several elements. | ||
Talaev A. D., Borodin V. V. LPWAN standards for mobile nodes' group interaction. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/391/Talaev_Borodin_rus.pdf The rapid development of IOT requires creation of group interaction networks. For large sensor networks creation, LPWAN networks (NB-IoT, LoRa, Bluetooth mesh, ZigBee) may be employed. Thus, a flexible adaptive structure of these standards can ensure enhanced reliability by additional nodes and alternative routes.
Group interaction allows the sensors to perform a distributed task solution.
The networks of group interaction possesses the following features:
– High-speed adaptive mechanisms;
– Sufficient distance to ensure the connectivity of the sensor network to each other and Peer-to-peer structure;
– Reduced power consumption due to limited resources of a node and sensors ability to transmit data for a long time without loss, as it is important for successful group processing.
Promising is application of standards such as LoRa, Bluetooth mesh and ZigBee for those operating on unlicensed frequencies.
Standards LoRa allows deploying large networks with the star topology, which is convenient for providers. On the other hand, the standard Bluetooth mesh allows building distributed Peer-to-peer networks and providing distributed processing of sensors data.
It is necessary to account for the possible movement of nodes in the network and their speed. For ZigBee, the time necessary for a node to enter the network may be several seconds. A restriction on the number of hops in the network exists as well.
The use of existing Wi-Fi standards or cellular systems does not allow deployment of sensors networks of group interaction with sufficient energy efficiency and relatively low costs as LPWAN networks. | ||
Evdokimenkov V. N., Kim R. V., Popov S. S., Galenkov A. A. Software for probabilistic-guaranteed estimation of aerial vehicle onboard equipment condition. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/9c0/Evdokimenkov_Kim_Popov_Galenkov_rus.pdf The article considers the purpose, functionality and architecture of the aircraft systems condition post-flight monitoring software. The program was developed for calculating the probabilistic estimates of aircraft systems technical condition and decision making on further aircraft safe operation. The program employsflight recorders data as primary information for analysis and relational database to accumulate pre-processed flight data, but it allows processing data stored in .xls and .txt files as well. Methods and algorithms used in the software under consideration are based on conception of the aircraft system reference pattern, which presumes the system representation by the reference set of points in the state space of parameters. The reference patterns are to be formed for each flight phase of the exact aircraft. Using the points appropriate to normal aircraft system operation, the reference patterns can be represented by the cumulative distribution function (CDF) of the Mahalanobis distance from the center of the pattern to each point of the reference set. The program allows select a set of flights and the flight phase to create the etalon set of points and calculate Mahalanobis distance CDF. To make a decision on the current condition of the exact system the probabilistic criterion (quantile) is computed after each flight using Mahalanobis distance CDF. The program package architecture is based on the «Layers» software pattern and includes three layers: presentation layer, business layer and database layer. The considered software may be useful as an additional tool for maintenance specialists during the whole aircraft operation period. | ||
Vasil’eva S. N., Kan Y. S. On linearization of perturbed motion model in the problem of ballistic trajectories scattering probabilistic analysis. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/154/Vasileva_Kan_rus.pdf The article considers the probabilistic analysis problem of ballistic impacts scattering at spherical Earth surface. The starting point of the trajectory is also located on the earth’s surface. Trajectories scattering is caused by a random perturbation of the initial velocity vector. The circular probable deviation is employed as a scattering characteristic. It represents the circle radius length, the probability of hitting which equals to 1/2, i.e. it concurs with quantile of 1/2 level for the norm of a random vector, characterizing the trajectory impact deflection from the nominal one. These vector components are computed using the equations of Keplerian theory of elliptic motion in the central gravitational field. They depend nonlinearly on the velocity perturbation vector. In this respect, the analytical obtaining of the quantile from the norm of this vector is impossible.
The velocity perturbations are assumed to be small compared to its nominal absolute value. The vector of small random parameters of velocity perturbation is modeled as an componentwise product of a small deterministic parameter and a vector of random parameters. It is assumed that the random parameters vector has a standard normal distribution with independent components. The article suggests the linearization method consisting in approximation of the above said non-linear dependence by the linear model, which is obtained by deviation vector Tailor expansion along the velocity perturbation vector. It is being proved, that the error occurring while such substitution is of the order of a small deterministic parameter.
As a model example, The authors consider the flight of a material point to a specified distance at the known values of nominal initial velocity, departure angle and azimuth. The computation results of the circular probable error by the Monte Carlo and linearization methods for a wide range of initial values are presented. Calculations of linearization method relative error compared to Monte Carlo method are also given. This error does not exceed 1.5%, which was confirmed by theoretical accuracy estimates of the linearization method, proposed in the article. | ||
Bortakovsky A. S., Shchelchkov K. A. A group time-optimal tasks of aerial vehicles. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/33c/Bortakovskiy_SHCHelchkov_rus.pdf The goal of the study consists in developing methods for forming the time optimal control laws for groups of objects. The problems of group performance find practical application in the field of controlling the groups of manned and unmanned aerial vehicles. There are also applications in biology and robotics. In the theory of optimal control such problems are new and insufficiently explored. The article considers four group performance problems. They are the task of simultaneous achieving one goal by a group of objects, the task of managing a group with its leader selection, the task of achieving several goals with a single or multiple sequential separation of active control objects from the carrier. The solution of these rather simple academic tasks allows developing and testing methods for optimal position control synthesis, which can be implemented in complex applied problems.
Optimal positional control developing is based on the method of dynamic programming, consisting in finding the price function (the Hamilton-Jacobi-Bellman function). In the problems under consideration, the centralized management of a group is based on the optimal decentralized positional control of individual mobile objects. The price function is formed from auxiliary functions, i.e. partial price functions for individual objects of the group.
The result of this work is the solution of the assigned group time-optimal problems, as well as the methods of constructing the price function and optimal positional control. The developed methods can be employed in the aerospace field while planning the aircraft groups’ application.
For theoretical studies in the field of optimal control of the groups of mobile objects, the solved problems can be employed as testing ones. The developed methods of the price function constructing can be employed for solving other more complex problems. Given that even in academic examples the solution is being found numerically, the application of the proposed methods of synthesis indissolubly related to the development of the appropriate approximate algorithms, as well as programs for the numerical implementation of these algorithms. | ||
Shchelykalin M. Y., Formatorov S. O. Analysis of incoming correspondence processing changing of a space industry enterprise while Redmine projects management system implementation. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/89f/SHCHelykalin_Formatorov_rus.pdf The article considers an improvement of the spacecraft onboard software development by correspondence workflow automation. The analysis of existing in MEDB «MARS» letters workflow was performed to identify the stage where the introduction of information technology would reduce the development time and increase quality. It was decided that the automation of the maximum number of steps is the the basic method to improve the existing process. The conclusion was made on the reason of information system creation to automate process of letters registration and control. The system requirements were formulated. Based on this requirements and terms of implementation, the decision was made to create the system based on Redmine project management system.
The Redmine system was set up and extended with some plugins to meet the standard tasks of letters registration and control process. The following plugins were created:
Plugins development process was supported by functional automatic tests. The tests were performed with Selenium automation browser tool.
The proposed solution has been successfully introduced into the production process and employed while the development of several spacecraft control systems, including KazSat-2, Electro-L, Elektro-L № 2, Elektro-L № 3, Spektr-R, Spektr-RG. | ||
Zamolotskikh O. A., Nikolaev A. V., Nikolaev A. V. Ballistic characteristics computing technique for identical models in conditions of a carrier aerodynamic interference. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/080/Zamolotskikh-Nikolaev_Nikolaev_rus.pdf One of the most important tasks of aircraft employing is the delivery of goods discharged from external suspension devices in a strictly designated area. However, while suspension and subsequent discharge of identical goods under the same conditions, but with different external components of the carrier aircraft suspension, significant deviations of the drop of goods from the calculated occur. To determine the causes leading to high values of the drift, simulation of the process of flow around the aircraft when loads were located at various external points of the suspension was performed in the ANSYS software complex. According to the simulation results, the conclusion was made that the main reason, leading to discrepancies in the results of discharges from different external points of the suspension, is aerodynamic interference (AI) from the carrier, which represented an additional aerodynamic forces and moments, leading to a change in the aerodynamic qualities of ballistic bodies. Thus, the problem of accounting for the changes in the aerodynamic qualities of loads, depending on the location in the mathematical model of the movement of the ballistic body, arises. The article presents method for accounting for the aerodynamic interference characteristics, as well as the development of a technique for the ballistic characteristics computing of the goods located on the external suspension devices in the conditions of aerodynamic interference.
The following conclusions can be drawn from the results:
1. The phenomenon of aerodynamic interference significantly distorts the aerodynamic characteristics accepted and used in the onboard complexes.
2. The quantitative change of aerodynamic qualities of the model induced by the AI should be accounted for in the function containing the cargo ballistic properties , i.e. ballistic characteristics.
3. The developed technique allows accounting for the individual specifics of the cargo geometry and ballistic properties and obtain ballistic characteristics, reflecting the real process more fully.
4. Since AI manifests itself briefly, it is necessary to develop an accounting method of the characteristics of AI in the onboard ballistic algorithm, which envisages both movement in the interference and unperturbed field of the atmosphere. | ||
Rusakov D. Y., Chernushin V. A. Defects imitation in multilayer honeycomb structure from polymer composite materials by honeycomb filler underrating method. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/a6b/Rusakov_CHernushin_rus.pdf Nondestructive control is utterly weak part of composite materials quality control. The most general non destructive control method of composite honeycomb structures is acoustic impedance method. To adjust defectoscope control parameters the sample with defects imitation is required.
The article compares the honeycomb underrating method for defects imitation and flat-bottom holes method. Advantages and disadvantages of both methods were analyzed.
The most general defects imitation method is flat-bottom holes method. However, this imitation method has a disadvantage. The defect area on sample larger becomes every time, than the defect area obtained from the mathematical model of this sample. With a honeycomb cell of a big size (the side length of 5 mm or more) this effect becomes rather crucial.
Another problem while applying imitation by flat-bottom holes method consists in impossibility of double-sided sample control. Thus, imitation of both sides is required, that makes the sample size much bigger.
Control of the sample while performing this this operation is realized by ID-91M acoustic impedance defectoscope. Extra control of the sample is performed via radiographic control.
A sample with two types of defect imitation was fabricated especially for this work. All in all, there were four defect imitators by flat-bottom holes method and four by honeycomb underrating method. The area of both pairs of imitators was equal in theory. Nevertheless, results of tests revealed that these areas are not equal. The area of imitators made by honeycomb underrating method was closer to the theoretical area of the defect.
As result of this work, we obtained data, confirming the advantage of the honeycomb underrating method compared to the flat-bottom holes method. | ||
Likhachev V. P., Sidorenko S. V. Noise immunity of images autofocusing algorithm by entropy minimum at complex background situation. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/306/Likhachev_Sidorenko_rus.pdf Modern SAR ensure a longer range, compared to optical systems, a faster (within a few seconds) radar image of a large land area receiving with a sub-meter resolution, as well as independence of the images quality from weather conditions and natural illumination state of the scenery.
Comparatively small weight-size indices of modern SAR allowed install them on unmanned aerial vehicles (UAVs) of small class, which application reduces significantly the operation costs and maintenance of a carrier. However, application of such UAVs as SAR carriers is associated with significant instabilities in the trajectory and flight speed due to atmospheric turbulence.
To form a high-quality radar image with given resolution in time scale close to the real one, it is necessary to obtain accurate information on the carrier motion parameters and, primarily, its flight speed.
Placing a high-precision inertial navigation system on a small class UAV is impossible, and application of navigation receivers under interference conditions does not ensure the required accuracy in estimating the SAR carrier speed while the radar image formation. To compensate the speed estimation error, various radar image autofocusing algorithms are employed, such as the radar image autofocusing with regard to the minimum entropy function. It does not require the presence of powerful point-like reflectors in the field of vision. However, to evaluate the efficiency, for example, in solving the problems of correcting navigation errors by the radar image in conditions of a large noise / signal ratio q, additional investigations are required.
The relevance of the article is determined by the need to form a radar image with a specified resolution in a time scale close to the real one, by a small SAR installed on the UAV, which lacks the capability to compensate for trajectory instabilities from information from the inertial navigation system, etc. In the presence of noise-masking interference and background reflections, it is necessary to determine the boundaries of the stable radar image autofocus algorithm functioning at minimum entropy.
The article deals with the operation of a radar station with digital SAR with the RLI autofocusing for a minimum of the entropy function in conditions of noise-masking interference and complex background situation. | ||
Usachov A. E., Mazo A. B., Kalinin E. I., Isayev S. A., Baranov P. A., Semilet N. A. Efficiency increasing of numerical modeling of turbulent flows by application of hybrid meshes with structured multi-scaled blocks and unstructured insertions. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/981/Usachev_Mazo_Kalinin_Isaev_Baranov_Semilet_rus.pdf Method of hybrid meshes was developed for the stationary and non-stationary internal turbulent incompressible flows numerical modeling. Numerical modeling of the internal turbulent flow in a flat parallel duct with cylindrical cavern located on its lower wall was performed to validate accuracy and stability of the method. The goal of the studies consisted in verifying the proposed methodologies realized in VP 2/3 code [6] (based on the hybrid mesh technology [7] and turbulence differential models) on various meshes. Three kinds of meshes such as a coarse hybrid mesh, a refined hybrid mesh with non-structured block and non-structured triangular mesh were analyzed.
An experimental setup to study 2D plane flow in parallel channel with circular cave was built in the Institute of Mechanics, Moscow State University [3]. Viscid incompressible flow was studied in a flat parallel duct with cylindrical cavern located inside one of the duct walls. The Reynolds number was 1.3 × 10^{5}.
The modelling methodology and numerical approaches are based on solving Reynolds averaged Navier-Stokes (RANS) equations for incompressible fluid and hybrid grids concept. While quantization of the convective flows through the control volume facets, the counter-flow schemes of a second order accuracy were applied [11].
The pressure was computed by semi-implicit methods (SIMPLEC), based on the SIMPLE procedure proposed by Patankar [10]. The VP2/3 bundled software, which is successfully employed for numerical modelling of various heat and mass exchange problems with viscous fluid and gas flows was developed based on this technique. Computations with different hybrid meshes are compared to the experimentally measured values of the velocity horizontal component in the center of the cavern and static pressure on the lower wall of the duct.
The verification and validation of numerical modelling of a flow in the duct with cylindrical cavern were performed with the differential model of Menter’s SST turbulence. Computed and experimental data demonstrated a close agreement. | ||
Markushin A. N., Baklanov A. V. Test results of washing-out of coked atomizers of NK family combustion chambers by mixture of kerosene with technical detergent. Trudy MAI, 2018, no 99, http://mai.ru//upload/iblock/1c1/Markushin_Baklanov_rus.pdf Ensuring reliable and failure-free performance of a gas turbine is the most foreground task for aeronautical engineering manufacturer. The combustion chamber is the most thermo-stressed part of the gas turbine with a great number of complicated gas-dynamic and thermodynamic process. Thus, the reliability of a gas turbine in many respects depends on a combustion chamber reliability. While aviation gas turbine with a multi-atomizer combustion chamber operation the combustion chamber fuel supply lines are subjected to coking due to low thermal stability of the supplied the fuel. It leads to premature engine removal. For this reason, the article presents the results of works on washing-out the partially coked atomizer by various of kerosene-technical detergent mixtures to define the more efficient of this mixture composition. The method of washing have been chosen due to the addition an antioxidant additive to fuel, or periodical combustion chamber washing-out by kerosene in mixture with active agents allowing decompose a carbon formation and a resinous depositing, as well as remove them together with fuel. The article describes the structure of the test bench and single-atomizer combustion chamber section, which was employed for testing eight partially coked nozzles. The article presents also the tests operation modes.
The results of the study revealed that the fuel mixture with technical detergent effectively removes deposits of thermal fuel decomposition from the coked atomizers. The maximum efficiency of carbon removing was obtained with the mixture of kerosene with 10-15% of technical detergent.
It follows, that this method is effective for realizing an atomizer channels cleaning channels, and may be recommended for application while the routine maintenance of gas turbine operating on liquid hydrocarbon fuel such as kerosene or diesel oil. | ||
Panev A. S. On motion of a rigid body with mobile internal mass on a horizontal plane in a viscous medium. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/1a8/Panyev_rus.pdf We consider a movement of a solid body carrying sliding single mass point. A body of M mass is situated on a horizontal plane, and a single mass point of m mass is moving inside it over circumference of R radius, which center coincides with the center of mass of the body, counterclock-wise. The forces of dry and viscous friction act between the body and the horizontal surface. Moreover, the angular velocity of the points’ circulatory movement is constant. We assume that at the initial instant the body stays at rest, and the moving mass occupies its lowest position
This work aims is complete qualitative investigation of all possible modes of motion body without the horizontal plane liftoff.
In addition to theoretical interest, the study of mechanical systems of this type can have an applied value, for example, as the creation of vibrating robots moving due to the forces of inertia that arise when moving internal masses. The advantage of such devices is that they do not require special propulsion (wheels, tracks, legs, and so forth.) And can be performed in an enclosure, the latter fact makes them resistant to attack by the external environment and allows to apply, on solid surfaces, and in liquids. Such devices are promising for the modern space industry. In particular, they can be useful for the study of celestial objects: asteroids, planets, solar systems and their satellites.
Based on the analytical and numerical studies made in this work we obtained the following conclusions. Three possible modes of motion were found, the conditions for their existence depend on the parameters of the problem: κ is the coefficient of dry friction,ν is the coefficient of viscous friction, and
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Kuroedov A. A., Borisov D. M., Semyonov P. A. Determining combustion zone acoustic admittance of non-metal and metalized energy condensed systems. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/0cc/Kuroedov_Borisov_Semenov_rus.pdf The work is devoted to the experimental study of combustion zone dynamic characteristics for metallized and non-metallized solid propellants. The goal of the study consists in developing a device to determine acoustic admittance and the pressure-response function of solid propellant combustion zone at various pressure pulsation frequencies and operation pressure.
The pulsed T-burner consisting of a classical T-burner and two auxiliary pressure pulsation generation (AG) chambers is proposed. Changing the T-chamber sections number allows varying frequency of created longitudinal vibrations combustion products, making it possible to measure acoustic admittance of the combustion zone in a wide frequency range. Nozzle design envisages the possibility of changing the throat diameter before launching by replacing the molybdenum liner. A pyrotechnic compound placed in the AG free space ensures the tearing up of metal diaphragm, clamped in the channel, connecting AG and T-burner.
To determine the solid propellant acoustic admittance a series of firings is being performed. For each firing cylindrical charges with a channel are prepared and glued to T-chamber cover. During the T-chamber firing without AG the installation, the operation time necessary for the right setting of time delay of triggering pyrotechnic compositions in AGs for the next firings is determined. Further firings are performed with AG, in which the decay constants of the two pressure pulses, created at the main operation segment, and at the end after both charges burning out are being fixed. Acoustic admittance of the solid propellant combustion zone and a function of combustion zone pressure-coupled response are calculated according to the obtained coefficients.
The acoustic admittances of a non-metallized solid propellant (AP / low-molecular rubber) and metallized propellant (AP / butyl-rubber /Al) were measured at frequencies in the range 150 to 850 Hz. Comparison of the obtained results to the published data indicates the perspective of the proposed installation implementation. A significant relative error of acoustic admittancehav and pressure-coupled response function determination requires more close attention to the technique of pulse pressure forming in the T-chamber.
The obtained acoustic admittance values can be used as boundary condition for solid fuel power plants acoustic stability calculation while employing various numeric methods. | ||
Sysoev O. E., Dobryshkin A. Y., Nein S. N. Analytical and experimental investigation of free oscillations of open shells from alloy D19 carrying a system of attached masses. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/a67/Sysoev_Dobryshkin_Neyn_rus.pdf Experimental studies have been carried out to determine the influence of the system of attached masses on the natural oscillations of shallow cylindrical shells of aluminum alloys, the results of which have been compared with theoretical calculations. The purpose of the experiment is to measure the free oscillations of an open, sloping cylindrical shell for various variations of the attached masses. Oscillations of an open, slender, thin-walled cylindrical shell, rectangular in plan, were measured using induction accelerometers. The theoretical calculation of the shell was carried out on the basis of the equations of motion of the theory of shallow shells, using the Bubnov-Galerkin method. A significant splitting of the flexural frequency spectrum is found, influenced not only by the systems of attached masses, but also by the values of the wave formation parameters, which depend on the relative geometric dimensions of the shell. The correspondence of analytical and experimental data is found, using the example of an open shell of alloy D19, which allows us to speak about the high quality of the study. A qualitative new analytical solution of the problem of determining the magnitude of the oscillation frequency of a shell carrying a system of attached masses is shown. For calculations, a hinged-supported open-shell model is used. The solution is based on the general equation of shell vibrations, a system of two differential equations describing small bending vibrations of the shell. On the basis of the general equation of oscillations of the shell (plate), an experimentally discrete nonlinear model of oscillations of a shallow shell bearing a system of attached masses with two degrees of freedom was obtained and confirmed experimentally. The experiment was carried out on a thin-walled cylindrical sloping open-shell model. The material of the sample is an aluminum alloy of the D-19 grade. Geometrical characteristics of the sample: R = 318 mm, L = 800 mm, H = 93 mm., δ = 0.4 mm. The shell is installed in a stand made in the laboratory of building structures. Experimental studies confirm theoretical studies. These studies can be used in the design of swimming machines, aircraft and other shells that have an attached mass. Carrying out of experimental studies has shown the validity of the obtained mathematical model, namely: the presence of a system of attached masses in an open cylindrical shell leads to splitting of the bending frequency spectrum of oscillations and the smaller of the split natural frequencies decreases at the same time. | ||
Chernomorskii A. I., Kuris E. D., Mel'nikov V. E. Control program for translational and rotational motion of Uniaxial Wheeled Module. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/96e/CHernomorskiy_Kuris_Melnikov_rus.pdf Uniaxial wheeled module (UWM) is one of the most perspective types of unmanned ground vehicle for environmental monitoring tasks, particularly aerodrome. This vehicle is capable of both carrying equipment, and managing angular orientation of the platform, on which it is mounted. Simple algorithms for forming control moments, developed by the UWM wheels’ drive motors, were obtained. These moments provide a quasi-optimal in time UWM movement from the starting position on the horizontal underlying surface to the final position at the given UWM orientation in these points of its stationary positions. Non-holonomic vehicle model was obtained on the assumption of the absence of wheels slippage relative to the underlying surface, and insignificance of the effect of the platform angular movement around wheel axis on the linear movement of the center of UWM wheel axis. Adequacy of this model was confirmed by the results of experimental studies of UWM developed in MAI. Two types of its trajectories of simple configuration, predetermining the minor time of the UWM’s movement realization. It was demonstrated analytically, that it was impossible to transfer the UWM from the starting stationary position to the final one with the given in this position course angle within a single switching of the moments signs. Thus, the first trajectory was split into two stages, and the second into three ones. In each stage, the moments are formed based on maximum principle of Pontryagin in the form of constant in modulus (at each stage) maximum possible values, using at the stages only one simultaneous switching of these moments’ signs.
Travelling times’ comparative evaluation for UWM moving along the two selected trajectories was performed, based on the developed algorithms for forming control moments of wheels’ drive motors. It revealed the dependency of these times from both azimuth angle and course angle of the UWM final position . | ||
Kulikov S. V., Shcerbakova V. M., Frolov A. V., Vikulova Y. M. Definition of a matrix idling cut open a non-uniform line when you change the deduction in one of the poles. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/b83/Kulikov_SHCHerbakova_Frolov_Vikulova_rus.pdf
Determination of properties of inhomogeneous lines for use in various filters. | ||
Kuli-zade M. E., Reshetnikova O. F., Skorokhod E. P. The development of kinetic models of the moving plasma. The Einstein coefficients for ion xenon.. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/d31/Kuli_Zade_Reshetnikova_Skorokhod_rus.pdf The study of the flows of a moving plasma, both experimental and theoretical, as well as the fundamental issues of plasmomechanics currently belong to the rapidly developing fields of science, which are used in solving the problems of engine building, rocket and space industry. In particular, the modeling of physicochemical processes is necessary for multilevel kinetics, low-temperature plasma spectroscopy, and optical diagnostics of plasma flows.
Einstein’s coefficients of spontaneous radiative transitions are the main terms of numerous kinetic equations, they are used to construct the state vectors of the plasma under investigation in the processing of spectra.
To compile the kinetic equations themselves, we need a scheme of levels and (what is fundamentally) their grouping, both for the XeI atom and for the XeII ion. The schemes compiled and supplemented in the quantum-defect approximation for the XeI atom and for the XeII ion make it possible to calculate the transitions that are absent in the reference edition [12].
In works from the list cited in [1, 2], on the study of the xenon plasma of the Hollow engine, little attention has been paid to the question: what levels and configurations should be taken into account in calculations. Usually in foreign publications, the averaged blocks are considered using the experimentally obtained constants, the kinetics for the atom, separately for the ion, is separately written. A joint model of the kinetics of excitations of an atom and an ion is not considered.
Calculations of the Einstein coefficients were carried out in the Coulomb approximation. The radial integrals were calculated using the Bates-Damgaard method. The angular dependences of the xenon ion are recorded in the LS – relationship. The values of the oscillator strengths and the probabilities of ~ 1000 radiative transitions of the xenon ion are given.
The averaging of the radiation constants is associated with the determination of the matrix element factor [11] (by adding the moments of dipole transitions). Recommendations are given on the use of tabular data of XeII in accordance with the chosen scheme of levels and configurations taken into account. | ||
Fedotov D. A., Skvortsov K. G. Investigation of the strength of puncture holes. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/e97/Fedotov_Skvartsov_rus.pdf The object of the present study is holes obtained by piercing the uncured polymer-fiber material of the structure. Puncture is carried out with the help of a pointed rod – indenter. The force field of the reinforcing fibers is not interrupted. The wall of the hole is thickened due to the increased content of fibers.
The aim of the study is to develop a hole punching technology, thread cutting by puncture, and also experimental study of the holes obtained.
Tensile tests carried out on multi-layered woven glass fiber-reinforced plastic samples with a hole of 8 mm showed a reduction in tensile strength in comparison with solid samples by 31.7% and 4.2%, respectively, for drilled and molded holes.
A special device was developed to pierce holes of various diameters in GRP plates up to 30 mm thick, as well as piercing elements for smooth holes and threaded holes.
Initially, the tensile test was carried out. Tests were made on samples cut from prefabricated plates in the size of 350×350 mm. To fabricate plates, T-13P cloth (100) was chosen, impregnated with binder EP-5122. The plates were made on a special device. The layers of fabric were stacked by alternating warp and weft. Such a technique made it possible to obtain characteristics of plate material, which are the same in all reinforcement directions. In the center of each plate we punctured holes.
18 plates with punctured holes in the center with a diameter of holes 6; 9; 13; 16; 18 and 20 mm were made. We made 3 plates for each diameter. We cut out of them the following samples: 1 sample with a punctured hole, 2 samples with holes drilled and 2 samples without holes. The width of the samples was equal to 3 hole diameters. Samples with holes of 20 mm were 50 mm wide. All samples were stretched to failure.
Based on the results of the tests, the following conclusions were drawn:
Further, the samples were subjected to cut tests. For the testing, 5 plates with punctured holes were made. Samples for testing were cut from the same slabs. In this case we had one sample with a punctured hole, and two with drilled holes. In the holes the bushings were inserted, through which the sample was loaded. On the one hand, the load was applied to the sample, and on the other hand it was applied to the pin. In such tests, the pin cuts the sample material along two planes.
Analysis of the test results showed that the breaking stresses on the cut in samples with punctured holes are 2-3 times larger than in the samples with drilled holes. This result can be explained by the fact that in the first case the threads of the reinforcing material near the hole are not cut, and the drilling cuts them.
Also we carried out tests to cut the thread obtained in the prepreg by the puncture method. For the production of plates with threaded holes, we made piercing elements which had a thread cut on the cylindrical part. We produced five such plates with different hole diameters. To test the thread in the holes we screwed rods with a corresponding thread into these holes. A tearing force was applied to the bolt until the thread was broken.
As a result of the tests, the following conclusion was drawn: the stresses on the cutting edge of the GRP thread have a value equal to the cutting strength of the GRP material. Thus puncture of the threaded hole allows to achieve the maximum value of the strength characteristics. | ||
Duong D. T. Model wing inviscid flow-around computation by finite element method of high accuracy in conditions of thin ice formation. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/638/Zyong-De-Tay_rus.pdf The article presents the model wing inviscid flow-around computation by finite element method of high accuracy in conditions of the thin ice formation. The goal of the article consists in solving the problem of flow-around MS(1)-317 profile and NACA 64A008 wing by non-viscous gas water suspension. The system of equations of water content in the framework of Euler approach is described. The system in itself is not hyperbolic, and regions of “vacuum”, where water content ρ tends to zero, appear. To eliminate the said problem the system regularizing was performed to make the system hyperbolic. The new primary variable r = lg ρ was introduced. The resulting modified water content equation system was solved by Galerkin method with discontinuous basis functions (RMG). Orthogonal polynomials are used as basis functions in RMG. Initial and boundary conditions were formulated. At the initial instant the aqueous dispersion mixture is considered moving together with the gas. Parameters on the solid surface were computed in a special way.
The problem solution is split into two stages. At the first stage, the inviscid dry gas flow-around the wing is computed. Then, the obtained field is used as the basic field, and the finely-dispersed aqueous mixture flow around the wing is calculated. The water suspension droplet, sticking to the wing surface (capture coefficient β), defines the probability of the thin ice appearance.
As an example, calcolations for two typical problems were performed: the flow around the MS(1)-317 profile and the NACA 64A008 wing. The obtained results were compared to the experimental data. It is shown, that in the case of moderate incidence angles, the RMG scheme of the third accuracy order ensures the calculation accuracy of the water droplet capture coefficient on the wing about the 5% order. It is acceptable in practice. | ||
Kalyagin M. Y. Modeling of aerial vehicles instrument bays by porous-composite impactors. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/617/Kalyagin_rus.pdf The article presents the model for parameters computation of an aerial vehicle’s (AV) instrument bay interaction with impediments (reinforced panels). The AV’s instrument bays are presented as porous-composite bodies, approaching the impediments at various angles. The viscoplastic flow in the panel material emerges under action of the highly intensive loads. Based on Renkin-Hugoniot theory, the author obtained the equations, describing the shock wave velocity in porous bodies. Computation results obtained employing these equations accord well with the laboratory tests results. The article presents the criterion of the beginning of viscoplastic flow progress in the panel under the action of impactor.
The proposed model of shock interaction allows obtain the laws of panel’s flexing and velocities alterations as a function of coordinates and time, as well as the distribution of stress and temperature.
Computaion resuts revealed that:
– The area of the intense viscoplastic flow was localized in a narrow region near the impactor contour;
– The destruction of the panel occurs at the stresses significantly exceeding the yield strength of the panel material;
– The effect of temperature growth on the physico-mechanical characteristics of the panel material in a first approximation can be ignored.
Calculations were performed for velocities of 300–900 m/s, panel thickness of 20 mm, and angles of interaction of 90° and 60°. The destruction of the panel occurs in the region where shear deformation reaches the limit value of p/4.
The results of the study can be used while solving problems of various bodies’ interaction. | ||
Alekseeva M. M. Solid fuel ramjet aircraft volumetric-mass configuration formation technique. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/89a/Alekseeva_rus.pdf The process of the volumetric-mass configuration formation (VMC) is one of the main stages a product shape formation. With the purpose of preliminary formation of the aircraft VMC, a complex mathematical model (CMM) and software to form shape of the system “Aircraft – power unit – fuel” were developed. Unlike earlier created, this CMM represents the uniform program complex intended for formation of a technical shape of aircraft and its power unit (PU) at stages of preliminary design. It allows compute not only thrust-economic and mass-size characteristics of an aircraft, but also geometric, aerodynamic, mass-volume characteristics and trajectory parameters of an aircraft movement by standard flight programs (profiles), as well as the effect of the properties of employed fuel on them.
The distinctive feature of this model its multidisciplinary approach and adaptedness to the optimization setting of the study. It allows optimize any airplane, engine and fuel parameters and their characteristics to form an optimal technical shape of the “Aircraft – power unit – fuel” system according to the selected effectiveness criteria. It gives the possibility to form a 3D model after configuring the project of a product to obtain more detailed information on aerodynamic characteristics (ADC), mass convergence of airframe and PU, computing of the center of masses and inertia moments of a product, preparing for 3D numerical modeling using the programs of 3D gas dynamic computation etc. The built-in universal model for computing equilibration thermodynamic characteristics of any gas mixture with account for K-phase allows evaluate effectiveness of application of this or that fuel for the given system. It expands greatly the abilities of both parametric and at optimization studies at various criteria. Dialog interface allows making changes in the project data and view the results in real time mode. It also provides availability of databases on starting and cruise solid fuels, structural materials and thermal-protective coating materials, ADC and characteristics of air-intake device which are updated daily and can be employed for the VMC formation.
Realization was performed by modern programming languages Fortran-95, Delphi and Win 32 API, using dynamic DLL technology. Verification of CMM is based on verification of the system model elements and on comparing the system criteria to real samples. With the help of this CMM, a number studies was performed to shape the “Aircraft–power unit–fuel” system. | ||
Proshkin V. Y., Kurmazenko E. A. Global criteria of efficiency and their hierarchy for life support systems for space stations crews. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/f1a/Proshkin_Kurmazenko_rus.pdf The authors suggest employ three global criteria of efficiency (GCE) to analyze life support systems (LSS) for space stations crews and planetary bases. These GCE integrate a number of LSS’s partial criteria (PC) such as survivability (G) (integrating such PCs as resource, reliability etc.); cost value (integrating PCs such as energy consumption, weight, servicing time, material cost etc), and comfort F (including such PCs as habitat, interaction with crew and other systems, layout, operation modes etc.).
The GCE hierarchy (significance) relative to each other depends on the type and characteristics of the LSS, its complexity and availability of means for reprocessing the source substances into final product within the system. Survivability is of most significance for regenerative LSS (RLSS), the cost value – for LSS on consumable components (LSS-C), and comfort – for emergency life support systems (LSS-E).
G > C > F. RLSS with a long operating time (several years), operating constantly, without maintenance.
G > F > C. RLSS, which operates periodically and for a short time (hours), with maintenance.
C > F > G. LSS-C with simple structure and processes.
C > G > F. LSS-C with more complex structure and processes (more probability of abnormal situations effecting the crew occurrence).
F > C > G. Emergency stock of consumables.
F > G > C. LSS-E for operation in abnormal situations on board.
G ≈ F ≈ C. Biotechnical LSS of future planetary bases, which will have a more significant cost value (high consumption of mass and energy) and comfort (specific requirements for greenhouses LSS).
While performing analysis, influence coefficients on three GCT kG , kC , kF are being determined for each parameter. The total coefficient is k_{Σ}_{ }=_{ }a_{1} k_{G }+_{ }a_{2} k_{C }+_{ }a_{3} k_{F }.
Weight coefficients a1 , a2 , a3 have their own values for each LSS and relative to each other correspond to the GCE hierarchy. For example, on board of International space station for Russian “Elektron-VM” system (О2 generation by water electrolysis): a_{1} = 9, a_{2} = 3, a_{3} = 1.
Application of this analysis in relation to existing and LSS being developed allows identify parameters and components with higher coefficients of influence and gives directions for constructional and operational modernization.
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Zareckiy M. V., Sidorenko A. S. Dynamic state of aviation products structures with weld junctions. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/790/Zaretskiy_Sidorenko_rus.pdf The reliability of aviation products structures depends on vibration intensity acting while joint flight of the product with carrier aeroplane and causing significant stress levels. The highest stress level is observed in the zones of structural irregularities (junctions and abrupt changes of cross-sections). Thus, the problem of credible determining of vibration characteristics in the product structure in the zones of irregularity under operation conditions is topical. At the same time, experimental studies of vibrations in the zones of jointing and irregularities are rather labor consuming and costly.
The article presents the methodology and results of numerical models development and calculated estimation data of vibration characteristics of an aviation product structure containing continuous weld junctions. Modeling of dynamic state of an aviation product was performed employing the system of solid-state modeling and complex structures design SolidWorks. Models developed employing solid finite elements allow account for structural irregularity, and estimate characteristics of components of spatial local deformation.
Based on the developed models, dynamic characteristics of a product structure and vibration acceleration characteristics at random kinematic loading for various variants of weld junctions were determined. Spectral densities and accelerations distribution dispersion in various points of the structure were plotted. Zones of maximum accelerations levels were determined corresponding to the conditions of joint flight with a carrier airplane. Significant effect of weld joint characteristics on the vibration acceleration levels of the product structure was registered.
The developed methodology can be applied to estimate characteristics of dynamic state of frames and structural components of aviation products suspensions at various weld joint characteristics and specified conditions of random loading. | ||
Isaev A. I., Skorobogatov S. V. Methodological aspects of burning process experimental research in combustion chambers of gas-turbine engines. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/ded/Isaev_Skorobogatov_rus.pdf Air-fuel mixture burning is a complex physical-chemical process, which can conventionally considered as fuel spraying, its evaporation, mixing with air, and air-fuel mixture ignition and burning, where all these processes occur simultaneously for the most part. With this, for the most part all these processes occur simultaneously, and until now there is no universal technique allowing account for all details of the phenomena under study while their mathematical modeling. Besides, apart from physical-chemical processes, the phenomena associated with streams gas dynamics are of great importance for the analysis. While spraying, liquid fuel is crushed into small droplets. The average diameter of these droplets stipulate the surface area, affecting thereby the liquid heating and its subsequent evaporation and mixing with air. The fuel combustion efficiency in its turn is determined by the composition of the fuel-air mixture, as well as organization of ignition and combustion of this mixture in the combustion chamber. With regard to the complexity of these processes and their interaction with each other, full-scale experiment is still an integral part of combustion chambers designing.
The goal of this article is to study the methodological aspects of modelling the processes in real combustion chamber, which occur in one and the same time interval. At the stage of full-scale experiments on the combustion process study, a number of difficulties associated with the nature of the phenomena under study occur. So, while a fuel-air mixture burning in the combustion chamber, the boundary between the combustion and mixing zones is of rather conditional character. Thereby, it makes it impossible to consider the processes occurring in these zones separately one from each other.
The authors proposed the design of the chamber’s test bench, allowing split the combustion and the mixing zones. Also the technique for overcoming limitations of measuring equipment while fuel-air mixture reached stoichiometric composition was considered. | ||
Stepanov R. N., Kozhevnikov I. A. Upgrade of monitoring instruments for aircraft liquid systems condition by industrial purity parameters. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/c58/Stepanov_Kozhevnikov_rus.pdf Solution to the problem of ensuring industrial cleanliness of the aircraft fluid systems’ and components’ working cavity allows significantly reduce the consumption of liquids; improve the reliability and service life of onboard equipment in aircraft operation; reduce the time spent on aircraft maintenance and repair, as well as the complexity of the production, repair and maintenance. This presents a significant gap in the implementation of the control of the contamination level of the working cavity side of the liquid systems.
For complex spatial geometry of the internal cavities of the aircraft liquid systems, relevant regulations stipulate the implementation of indirect control of pollution by changing the concentration of the contaminants resulting from the controlled VSA of the liquid. In these conditions, the procedure for fluid sampling for subsequent system analysis is of special importance.
Simulation results confirmed experimental studies demonstrating the unpredictability of the contaminant particle distribution over the cross section of the pipeline at various points in time with the same specified initial conditions. It indicates the impossibility of guaranteeing the reliability of the liquid sample at its point or slot selection.
To improve reliability of the fluid sample technical solutions for sampling devices that implement two methods of selecting a volume and a point of fluid sampling were developed:
– the full flow sampling device provides volumetric sampling, maximally identical to the analytical control, from which it was originated, designed for ground maintenance of an aircraft,
– the sampling device of a needle-type point ensures isokinetic sampling, constructively, with minimal weight and size parameters in a normalized embedded rebar elements of aircraft pipeline systems, intended for placement directly in on-board systems. | ||
Kudryavtsev S. I. Studying the safe flight termination ballistic scheme of manned transport spacecraft engine module . Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/cec/Kudryavtsev_rus.pdf The problem of safe flight termination organization for engine module (EM) of a prospective manned transport spacecraft (MTS) in the case of descent from the Earth’s artificial satellite orbit and high-precision landing of reentry module (RM) on Russian territory is considered. In MTS project the reboost of EM after its separation from RM after MTS deorbitation is planned in order to provide its orbital life-time on several orbits. Then EM will be deboosted for drowning its unburned elements of structure (UES) in desert area in the South of Pacific. Such a scenario of MTS descent will eliminate the possibility of damage for the population and objects of ground infrastructure near RM landing site. The features of EM reboost maneuver to ensure UES drowning in permitted region are studied. As a result elliptic pre-descent EM orbit has a very adverse position of perigee relatively the target drowning area. So, additional fuel consumption for reliable EM UES srowning will be required. The features of EM descent from elliptic pre-descent orbit are also analyzed. Dependence of longitudinal size of UES drowning points dispersion area (SPDA) vs deorbiting delta-V value is given. The purpose of trajectory design consists in selecting minimum delta-V then SPDA is still inside of permitted area borders. Elliptic profile of EM pre-descent orbit causes a specific effect of some disturbances such as engine thrust uncertainty to the total SPDA size. This study permits to determine the way to decrease SPDA size for the same fuel consumption. Fuel consumption for EM safe flight termination including fuel for EM reboost and final deorbiting is estimated. Scenarios of MTS descent for the cases of RM landing in various regions of Russia are given. | ||
Kozyaychev A. N. Studying algorithm of bank angle limitation near the Earth surface employing test bench. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/911/Kozyaychev_rus.pdf The relevance of the problem of runway surface contacting with a wing or a nacelle for the modern airliners (wing or nacelle strike) is presented in the article. To solve of this problem the author suggests limit the maximal bank angle near a runway surface. It is suggested to employ the dependence of maximal bank angle on flight altitude. The description of the bank angle protection algorithm near ground is based on the principle of switching between a control signal from the pilot and a signal for stabilization of the set maximal bank angle in case of its surpassing. To demonstrate functioning and performing simulator studies, the of bank angle protection near ground algorithm was included in a flight control system algorithms of the perspective medium-range airliner.
The results of the studies of the of bank angle protection near ground algorithm obtained at the TsAGI flight simulator with participation of test pilots are presented. Various options of roll control at take-off, landing and maneuvering on roll near ground including landings with a crosswind and with a gust of crosswind were considered. In th course of the studies at flight simulator of the of bank angle protection near ground the algorithm was modified based on proposal of test pilots. The modified bank angle protection near ground algorithm was highly appreciated by pilots as the function increasing comfort of operation, especially in cross wind when maneuvering on a roll near ground. In addition, this algorithm was recommended by test pilots for including in algorithms of a flight control system of perspective airliners. | ||
Ulybyshev S. Y. Launching a group of microsatellites employing intermediate orbit with synchronous precession. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/a20/Ulybyshev_rus.pdf The paper considers the task of launching a grouping of microsatellites employing intermediate orbits, possessing the property of synchronous precession of the ascending node longitude relative to the working orbit. As launch vehicle the article considers the “Soyuz-2.1 b” with launch block “Volga”, which after separation of the payload performs the inundation maneuver. The proposed scheme envisages separation of satellites from launch vehicles in the intermediate orbit. Then they are independently translated into the working orbit. This allows increase the mass delivered payload and reduce deployment time segment of the satellite system (SS) with installation of microsatellites in specified positions on the working orbit to 1.5 days. It reduces the required cost of fuel on the injection module to the problem of inundating. The simultaneous launch the grouping microsatellite segment SS into orbit with synchronous precession allows employ it as the standby orbit and significantly reduce the time of recovery of SS in case of failure of one of the microsatellite in the working orbit. The costs of fuel herewith for shifting standby microsatellite to the working orbit will correspond to nominal values for other aggregates from the given segment of SS. The article presents the methodology for evaluating costs of fuel and characteristic velocity for operation of putting a microsatellites grouping into intermediate orbit, bringing them to the working orbit and performing inundation maneuver by the launching block.
Comparison on time and energy indicators with the traditional option of putting groups of microsatellites directly on the working orbit when after separation apparatuses are set in the desired operating position through re-phasing maneuvers. The revealed advantages in terms of increasing mass of a payload delivered to an intermediate orbit are substantially dependent on the magnitude of the orbital inclination and the mostly tangible for near-polar deviations from 75° to 105°. While putting microsatellite groupings into near-polar orbits the additional payload mass may be comparable to the mass of a microsatellite itself. | ||
Alekseev A. V., Doroshin A. V., Yeromenko A. V., Krikunov M. M., Nedovesov M. O. Dynamics of a composite spacecraft with movable unit in three-axis gimbal. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/1d3/Alekseev_Doroshin_Eremenko_Krikunov_Nedovesov_rus.pdf The presented work is associated with modelling of angular motion of a variable configuration spacecraft caused by the presence of the additional movable rigid body inside the main carrier body fixed in the gimbal. The internal body is a movable unit of various functional purposes, such as antennae, telescope or operating component of a remote sensing system.
As a basis for considering a spacecraft in this problem, we can employ the model of double rotation of a spacecraft with movable longitudinal axis (on two transversal angles). In this case the presence of two additional degrees of freedom, allowing model the relative angular motion of the body-rotor relative to the carrier body, the mechanical structure of a spacecraft with double rotation is substantially enriched in the sense of functionality and dynamics.
The 3D relative motion of the internal body with respect to the main body of the spacecraft can be realized by means of a triaxial gimbal suspension. Then the considered mechanical system will have six degrees of freedom and allow ensure the necessary spatial orientation of the internal body, as well as fulfill the technical task of the spacecraft in its functional purpose.
For example, such mechanical systems and corresponding structural schemes can be employed for allocation of mobile equipment in a spacecraft, and orientating/redirecting/correcting its angular position by dint of internal drives fixed in the main body of a spacecraft.
As such equipment one can indicate, for example, massive manipulators, antennas, telescopes, movable nozzles of propulsion systems, structural elements of space tether systems, etc.
The mathematical model of angular motion of the considered system was obtained employing dynamical theorems and Lagrange’s formalism.
Equations of angular motion of a spacecraft with variable configuration without any constraints on relative rotation angles of the internal body/unit were obtained in this work. The authors performed numerical modeling of dynamics of movement without a spacecraft torque in case of internal control moments nonexistence.
The topicality of the work and its practical significance are characterized by the current intensification of the development of new modern platforms of nano-satellites, containing multifunctional mobile elements. | ||
Liang Q. ., Litvinenko Y. A., Stepanov O. A. Analysis of Attitude Reference System Accuracy versus Rotation Angle Sensor Errors. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/84b/Lyan-TSin_Litvinenko_Stepanov_rus.pdf At present, various methods of compensation for errors in orientation systems and Inertial Navigation Systems (INS) based on the rotation modulation technique are widely used. This method can enhance the autonomy of orientation system and navigation system and allows the system to operate for a long time even on relatively coarse sensors.
The data processing problem of attitude and heading reference system based on rotation modulation technique is studied in this article. A novel orientation system consisting of two micromechanical IMUs mounted on two separate rotary platforms with orthogonal axes is proposed. It can improve attitude system performance while reducing requirements for external sensors. This structure allows estimate errors of angular rate sensors without dynamic motion model of the object and any other external information. Though, in this case, the accuracy of the orientation system under consideration depends not only on the IMU measurement errors, but also on the encoder measurement errors of the angular positions of the platforms.
The error of the angle sensor consists of two components: constant and random error. Based on covariance analysis, the accuracy of the gyroscope errors was estimated employing various error level of angle sensors. It has been proved that the constant error component of the angle sensor has the same effect as misalignment angles, and the random error component affects the accuracy of the orientation system in the way similar to gyro measurement noise. The resulting data is very useful for designing the attitude and heading reference system based on two units of micromechanical gyroscopes, especially for selecting the type of micromechanical gyroscopes and angle measurement sensors. | ||
Gusenitsa Y. N., Dorozhko I. V., Kochanov I. A., Petukhov A. B. Scientific-methods approach to evaluating readiness of complex technical systems with account for metrological assurance. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/b76/Gusenitsa_Dorozhko_Kochanov_Petukhov_rus.pdf Substantiated evaluation of metrological assurance procedures effect on readiness for application is necessary while complex technical systems design and maintenance of their life cycle. It requires development of new complex models, connecting reliability figures with indices of technical condition.
The proposed approach and models are based on fundamental concepts and equations of the reliability theory of technical systems. The model proposed in the article is based on well-known and well-tested apparatus of Markov random processes, and analytical dependences obtained from the solution of systems of equations of Kolmogorov-Chapman, describing the developed model.
Mathematical models binding the coefficient of readiness, control reliability and the probability of metrological activities successful implementation of complex technical systems were developed. The analytical dependence linking the indicators of reliability of complex technical complex and the performance of the process control and metrological procedures was obtained. The proposed network model for obtaining the probability of successful implementation on metrological support of complex technical systems was suggested. The article presents a calculated example of the evaluation of the effect of metrological assurance procedures on the maintenance of readiness to apply complex technical systems. Analysis of the results allows draw inferences on the metrological assurance procedures degree of effect on the maintenance of readiness to use complex technical systems.
The proposed scientific and methodical approach can be employed while complex technical systems development, as well as justifying the composition and characteristics of technical means of metrological assurance.
The obtained analytical relationship may present practical interest for military representatives, employees of bodies of state certification, industry representatives. It can be used also for formation and justification of reliability requirements, as well as requirements to metrological support in tactical and technical tasks for development (modernization) of complex technical systems, as well as to account for the effect of activities of metrological assurance on availability of complex technical systems at all stages of the life cycle. | ||
Lunev E. M., Neretin E. S., Budkov A. S. Performing trajectory guidance algorithms testing at searching modeling bench. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/873/Lunev_Neretin_Budkov_rus.pdf Airspace is becoming increasingly saturated due to heavier traffic in specific dense areas. This necessitates a reduction in aircraft separation while maintaining the equivalent level of safety. It is clear that increasing airspace capacity, enhancing operational efficiency and fuel savings, while ensuring the best safety level of air traffic cannot be reached without combined employing of air and ground elements. New implementations being studied now require aircraft to maintain a specified level of accuracy and precision in the position update in all flight phases and in particular during aircraft landing. Recent navigation systems offer the required navigation performance to achieve these objectives, in conjunction with increased routing flexibility. Based on today’s forecast, some areas seem more appropriate for a new type of operation such as the so-called Area Navigation or RNAV, the Required Navigation Performance (RNP) concept, the Future Air Navigation System (FANS A and B) enhancement concept and new approach and landing capabilities based on FMS (so-called FMS landing system) or FLS (Flight Management Landing System). RNAV involves the development of navigation procedures based on instrument flight (particularly important in adverse weather conditions), enabling aircraft to fly point-to-point without conventional ground-based radio navigation aids. It can be used en-route in association with the RNP concept, but also for terminal area navigation (approach phase) and for instrument approach procedures. RNP is a navigation element that is expected to affect current and future existing airspace structures. It concerns navigation performance accuracy that is essential to fly the aircraft in RNP airspace. Aircraft must meet or exceed these performance and precision requirements to fly in that airspace. RNAV and RNP are two key elements of a more global concept that is FANS. This new enhanced concept involves not only navigation (with RNAV and RNP), but also surveillance and communication areas through an air traffic management link. Surveillance will allow the Air Traffic Control (ATC) to receive the aircraft position and its planned route in order to reduce aircraft separation and communication will assist in the automatic sharing of real-time information and digital communication between pilots and ATC. For these reasons FANS can be seen as a chain linking a pilot and a traffic controller.
For this concept of navigation, trajectory guidance algorithms were developed and tested. Results of the test reveal that the accuracy of the developed algorithms is high enough to provide a new navigation concept. | ||
Mikhailin D. A., Alliluyeva N. V., Rudenko E. M. Comparative analysis of the effectiveness of genetic algorithms the routing of the flight, taking into account their different computational complexity and multicriteria tasks. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/851/Mikhaylin_Allilueva_Rudenko_rus.pdf The paper presents results of the genetic algorithms research. This algorithm solves routing problem the aircraft executes the automatic flight on a pre-laid in memory of his computer flight mission. The cases of single- and multiobjective implementation of the genetic algorithm.
The multicriteria of routing tasks decision can be performed in two stages:
– finding a plurality of routes connecting a start and end point;
– verify the achievements in them the values of all criteria to select the best options.
Multiple routes selecting in a graph between two vertices can be carried out on the basis of minimizing the target function graph.
Estimated computational complexity of the described algorithm one criterion. It is shown, that when a large number of vertices and edges of a graph minimizing the objective function method the most beneficial in the development of preflight tasks.
In real conditions of planning the generated flight plan to meet a number of sometimes conflicting requirements of cost, flight duration, the total importance included in the plan of points. Their importance is uneven and variable, the timeliness of the observations according to the given schedule, etc. The essence of the alternative approach is that the full planned route is divided into several sections (blocks), each of which the dominant one private criteria. This method is suggested by the practice of observation, when one area important the timeliness, on the other – the economy. Thus, the objective functions of genetic algorithm are specified criteria. After the procedure, the formation of “elite” based on specify criteria starts the procedure of “crossing”. It is produced by blocks permutations of intermediate route points in the flight mission and provides a sufficient number of “descendants”. Then, inside all three blocks of the interblock points performs “mutation” that will be performed only between the boundary of points.
It is shown that due to the high performance of modern on-Board computers, implementing complex routing algorithms when observing terrestrial objects with a specified flight schedule does not cause difficulties.
On the basis of simulation results the performance of the algorithms a comparative analysis of their work effectiveness. | ||
Krikov D. S. Frequency spectrum synthesizers in radio electronic systems. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/802/Krikov_rus.pdf Frequency synthesizers (FS) find wide application in modern radio electronic systems (RES), such as mobile communications, precision measuring devices, radar and radio navigation systems. The development of new and promising RES as well as the outdated radio engineering systems modernization requires more advanced, in terms of technical parameters, FSs. The article examines mobile devices, measuring equipment, radio direction-finders and transceiver modules. A structural diagram, technical data on the capabilities of the device and an analysis of its operation are presented for each type of devices. Based on the results of the analysis, conclusions are to be made on the method of frequency synthesis, FS quantitative and qualitative characteristics, and trends for their improvement. In the field of mobile communications, engineers are trying to reduce weight, size and power consumption of microcircuits being a part of mobile devices, including the FS chip. Qualitative development of measuring devices requires time reduction of frequency tuning of the FS to the microsecond-nanosecond range. Radar systems require not only high speed, but also low levels of spectral components and phase noise of the FS. For radar systems employing active phased array antennas the critical parameters of FS are weight, size, power consumption and cost. The current level of FS based on digital phase-locked loop (PLL) with integer or fractional frequency division factor, digital direct synthesis and hybrid structures does not allow achieving high values of certain FS parameters, without degrading the other.
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Mikhaylov V. Y., Vitomsky E. V. Models for performance evaluation of a variant of fast search device over code sequence ensemble delay. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/eb5/Mikhaylov_Vitomskiy_rus.pdf Considered are async-targeted and control-measurement aerospace systems using complex coded signals. This work is devoted to the creation of models for performance estimation of the processing method and delay acquisition devices based on fast conversions.
The use of a variety of simplified methods and search algorithms are limited when limited observation time and high requirements to synchronization reliability and accuracy. The solution based on principles and mathematical models developed by the authors: principle of the fast conversions in Galois fields, algebraic model and structure of the delay acquisition device of the subclass code sequences. Key features of the processing method are receiving “in General” in two stages and accumulation of the symbols of the set synchronized by the delay of short sequences, which generated by the samples of the initial code sequence. Usually adopted buffering the implementation phase detection not used in the present embodiment search schema, which is usually required when performing other fast transformations methods.
Two search schemes are considered: an optimal and two-stage quasi-optimal scheme with a detector in the first search stage. Two channel models for different modes of operation of the schemes are constructed. They are makes it possible to choose the detectors threshold. Event model for these schemes built to their performance estimation. Based on these models analytical estimates of loss time to search were obtained. The developed two-stage quasi-optimal scheme version slightly loses on time in relation to the optimal scheme. This allowed us to justify increases energy efficiency of two-stage quasi-optimal scheme with a detector in the first search stage. | ||
Maslakov M. L. New methods of adaptive signal correction in aviation HF data transmission modem. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/e53/Maslakov_rus.pdf The importance and need for HF data transmission lines is increasing greatly with expanding of the aviation industry and innovation of requirements for air traffic services and airspace control over the Arctic region and ocean areas. Currently, the increased requirements to bit error rate and data transmission rate can be considered in the following areas:
– design of adaptive filtering algorithms;
– design of adaptive correction methods and principles;
– design of the new signal structures.
Recently, the author is working on all these areas. The article presents the following methods developed by the author:
– application of guard intervals;
– method of adaptive correction with guard intervals compensation;
– new algorithm of adaptive correction with decision feedback;
– methods of adaptive correction with quasi-coherent, weight quasi-coherent and in-phase quasi-coherent summation of test signals;
– method of non-test adaptive correction;
– algorithm of non-test adaptive correction with decision feedback.
The results of bit error rate numerical modeling obtained according to the methods considered in this article and algorithms of the adaptive signal correction are shown.
The presented methods can be used both in newly designed and in existing aviation HF data modems. These methods allow reduce a bit error rate and the probability of the information packet loss, as well as increase the data rate (up to 30%) in definite cases.
Some of the methods considered were implemented in a serial modem layout and tested on a real HF channel. All methods developed by the author were patented in Russian Federation. | ||
Bulygin M. L., Markova A. S., Mullov K. D. Multi-channel ScanSAR mode realization in a space-based SAR. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/d18/Bulygin_Markova_Mullov_rus.pdf This paper discusses implementation of a space-based synthetic aperture radar (SAR) multi-channel ScanSAR mode. Employing the digital active electronically scanned array (AESA) allows forming a multi-beam pattern and implement high resolution multi-channel SAR modes. One option is implementation of the multi-channel ScanSAR mode.
Computation of imaging characteristics and SAR parameters are given for multi-channel ScanSAR mode. For example, using K = 4 antenna beams (channels) allows scanning M = 3 partial strips (total swath of 70.29 km, elevation angle of 40°) with a resolution of about 3.7 m. For single channel SAR system with aperture size 4 × 1.6 m resolution is 8 m.
SAR digital AESA was realized as a multi-segment antenna. Each segment is completely autonomous and allows form, transmit, receive and process signals. This architecture requires an exact synchronization of the segments with each other. Synchronous operation and management of all segments is ensured by the on-board processor.
Intersegmental time synchronization is realized as follows. For transmition synchronization in the samples of the linear frequency modulation probe signal, a linear phase shift is added. At the receiving point, delay filters are used to synchronize signals in each segment. These approaches allow increasing the synchronization accuracy by 20 times.
The presented synchronization methods are implemented employing high-speed field-programmable gate array. To create a fault-tolerant firmware realizing high-speed signal processing, it is necessary to account for the specific conditions of the on-board SAR equipment in space functioning. This requires selecting the appropriate hardware in the design of the SAR system.
Thus, the multichannel scanning mode employing allows improve significantly the radar imaging characteristics. Implementation of this mode requires solving the problem of an intersegmental synchronization of on-board equipment. At the same time, the on-board equipment and its firmware must meet the requirements of fault tolerance in space.
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Ronzhin A. L., Nguen V. V., Solenaya O. Y. Analysis of the problems of unmanned flying manipulators development and UAV physical interaction with ground objects. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/3ee/Ronzhin_Nguen_Solenaya_rus.pdf The ability of aerial unmanned vehicles to manipulate or carry over surrounding objects, expands greatly the types of missions and application areas, enhancing the operator's ability to perform dirty, dangerous or monotonous operations. To date, employing of unmanned aerial vehicles (UAVs) for direct interaction with the environment is still limited due to its instability. Adding an onboard manipulation system to a UAV significantly complicates functioning algorithms, structure and leads to an increase in overall dimensions. The physical interaction of the manipulator with objects affects the UAV instability, which in turn leads to difficulties in the UAV positioning and reduces the accuracy of gripper guidance. In addition, the physical interaction of the manipulator with objects requires UAV's higher power resources. The article analyzes modern research of UAVs with a manipulator, including flight control problems, avoidance of contact with the earth, surrounding space, as well as manipulations with the captured object. Developing mobile manipulator of unmanned aerial vehicle (MM-UAV) is accompanied by a much greater number of difficulties than the creating traditional ground-based robots, performing the tasks of movement together with manipulation. The most difficult issue is the lack of a stable platform in the air. Ground vehicles can stop to perform operations and perform precise manipulations in a stable state, while MM-UAV in most cases does not have this capability. In fact, even employing robust flight stabilization systems, the MM-UAV airborne platform will be situated in a certain area of space, lacking herewith the precise fixed coordinates, especially while out-door operations. The lack of stability of the aerial platform can be partially compensated by manipulator control. The range of manipulator movements and the field of view of the sensors also depend on the side, with which the platform approaches the object. The body of the air platform itself is limiting the workspace of the manipulator. Thus, to increase it, in most cases the manipulator is mounted directly to the lower part of the platform. Still, experiments are performed on full-scale models rarely enough, mainly it is a computer or combined simulation, where the model of the manipulator is suspended in a special frame that simulates the UAV free movement. Based on the analysis, a list of new problems arising in the physical interaction of UAVs with objects through an embedded manipulator is formulated. The above said tasks and requirements allow defining the UAV hardware and software parameters necessary for manipulating and transporting ground objects, as well as interacting with ground-based service robotic platforms and other collaborative robots.
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Makarenkova N. A. Controlling the kinetic moment of the solar sail by changing of the reflectivity of its surface. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/e44/Makarenkova_rus.pdf In the article, the management of a solar sail, which uses the pressure of sunlight to move, is considered. It is a promising spacecraft, since it does not require the consumption of rocket fuel. This is especially important in the case of long missions. To achieve the required orbits, it is necessary to periodically change the orientation of the sail according to the specified program. Therefore, the problem of controlling the spatial rotation of the solar sail without the expense of the working fluid is especially important and relevant. The solar sail, represented in the form of a thin rotating mirror film attached to a cylindrical rigid insert, is considered. The flywheel is introduced to compensate the kinetic moment of the system “rigid ins ert – film”. In this case, the reorientation of the spacecraft is possible due to a change in the angle between the vectors of the kinetic moments of the structural elements. The solar sail will rotate about an axis that coincides with the sum of these vectors. In this case, the design in which the kinetic moments of the flywheel and the system “rigid insert – film” are equal in absolute val ue, is most preferable. In this case, any desired turn can be reported to the solar sail for an arbitrarily small change in the angle between the vectors of the kinetic moments of the elements of the structure, and therefore for arbitrarily small energy expenditure. In this case, the instrument compartment can occupy a fixed spatial position after reorientation. The imbalance of the vectors of the flywheel kinetic moments and the “rigid insert–film” system will inevitably arise during the long-term operation of the solar sail in orbit. This will lead to unwanted rotation of the instrument compartment. It is proposed to use a change in the reflectivity of the film as an external control action. The algorithm for controlling the solar sail, which allows it to be reoriented to the required angle, has been developed. It is established that in comparison with the spatial rotation only due to the forces of sunlight pressure, the control time has decreased more than twice, and the energy consumption has decreased by 4.5 times. The algorithm that allows to eliminate the imbalance of the vectors of the kinetic moments of the “rigid insert–film” system and the flywheel, is also developed. | ||
Rybnikov S. I., Nguyen T. S. Improving the accuracy of lateral movement control of the medium-haul aircraft using the Kalman observer of alternating wind disturbance. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/a6d/Rybnikov_Nguen-Tkhan-SHon_rus.pdf Currently, many accidents are associated with bad weather. This is because the aircraft and crew control system does not accurately predict the impact of external factors of a complex meteorological conditions on the flight process. Therefore, the requirement to develop a system for an accurate assessment of the environmental impact on an airplane is very important. Factors of meteorological conditions include: wind, humidity, air density, temperature. Synthesis of the automatic lateral movement control system in the mode of turn in unfavorable weather conditions (presence of a side wind) is a complex task. This work considers the development of a system for assessing the influence of the side wind on the movement of the aircraft.
The purpose of this article is to improve the quality of the lateral movement control process of the medium-haul airplane by minimizing the static error of deviation from the specified track with the introduction of the signal f or estimating the angle of the side wind and the slip angle in the control law. The input signals (angle of the course, roll, angular velocities) are measured by the BINS.
To obtain an estimate of the slip angle, the angle of the side wind and the drift angle from the given path, a Kalman filter is used, constructed using a linear stationary mathematical model of lateral motion of the aircraft [1]. As a result of the work, Kalman’s discrete filter was created, which allows to provide accuracy of obtaining estimates of the angle of slip, wind angle and angle of drift, which are subsequently introduced into the control law.
The simulation results confirmed the hypothesized hypothesis that the introduction of additional estimated parameters for the motion of the medium-haul aircraft improved the characteristics of transients when working off the deviation from a given track line in the presence of a side wind. In particular, when one-sided and two-sided gusts are acting at a speed of up to 10 m / s, the error of position of the plane concerning the set trajectory of system compensation of indignation decreases approximately by 3 times. In this case, the smaller the step of the discrete Kalman Filter, the more accurate the perturbation estimate it performs.
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Nguyen Viet H. N., Ha M. T. Formalization of the problem of optimal target information distribution from spacecraft to ground data processing stations. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/4dd/Nguen-Viet-KHoay-Nam_KHa-Man-Tkhang_rus.pdf Targeted operation of a space system includes a management of the targeted application of satellites, receiving information, processing and transmission to consumers.
At the same time, the question of the rational distribution of information obtained in an inhomogeneous ground infrastructure, places of its storage and further processing requires a more detailed study.
The solution to this problem should ensure, on the one hand, the maximum value of the information, and on the other, its economic attractiveness to the consumer.
The paper proposes a formalization of the problem of optimal distribution of the targeted information fr om satellites to ground data processing stations (GDPSs) and the methodical approach to its solution, which focuses on the creation of specialized software.
We assumed that the distribution destination information from the spacecraft to the ground data processing stations proceeds sequentially. The mathematical formulation of the problem includes models of physical resources; a query model; model assignment request; constraint model; model of residual available resources; model initial data; problem statement. At the same time, the task can be substantially simplified by conventionally dividing it into two subtasks.
Task 1 consists in constructing the optimal route for the passage of an application through ground stations with known intermediate stations for storing / reading information. The initial station can be a GDPS, wh ere the primary information is stored; a GDPS, which stores the intermediate results of processing previous applications that meet the requirements of the current processed. The end of the route is the consumer.
Task 2 involves determining the optimal allocation of the stored information with the statistics of the applications and their geographic information binding.
This task can also be considered as an optimization, for which:
For a small number of nodes and user requests, the optimal distribution problem can be solved by an enumeration method. Otherwise, one of the following methods can be used: the method of linear convolution of criteria, the Pareto method and its modifications, the method of successive concessions and limitations, the confident judgment method.
The conditions for the applicability of the proposed approach can be divided into several groups: the conditions for applying a methodical approach to solving the posed problem, the conditions for the adequacy of mathematical models of objects and processes, the conditions for the applicability of the initial data | ||
Solovjeva I. A., Solovjev D. S., Litovka Y. V., Korobova I. L. Modification of analytic hierarchy process to enhance decisions made objectivity. Trudy MAI, 2018, no 98, http://mai.ru//upload/iblock/5ab/Soloveva_Solovev_Litovka_Korobova_rus.pdf Units and components of aviation technology are subjected to corrosion processes while in service. Galvanic coatings are employed to repair parts, damaged by corrosion, and improve their protective and decorative characteristics.
The problems emerging while preparing electroplating industries relate to the class of weakly structured and multi-criteria problems, in a number of cases not subjected to formalization whatsoever. Thus, the solution of these problems can be obtained employing the intuition, experience and knowledge of the person making the decision. To solve these problems, decision support systems based on user and computer dialogue using artificial neural networks, production fuzzy models of knowledge and genetic algorithms are already being employed. In its turn, there are no works aimed at finding solutions to the emerging problems using methods of decision theory. The authors give preference to the analytic hierarchy process for solving the problems under consideration due to its universality. However, this method is not devoid of subjectivity in evaluating the alternatives in question when choosing a solution. The authors suggest a modification of the traditional analytic hierarchy process, which is aimed at reducing the share of experts participation in the decision making process. It is assumed, that some of the criteria by which alternatives are evaluated are given numerically. The authors suggest evaluate alternatives by such criteria as the ratio of their values, which allows get rid of the 9-point scale. When calculating weight factors, a function is introduced that returns 1 or —1, depending on the criterion minimization or maximization, to match the best alternative of the considered criterion to the maximum weighting factor. In this case, the calculations of the consistency index and the consistency relation become unnecessary. These innovations make allow exclude an expert when assessing a significant amount of quantitative data and, consequently, avoid variants of the estimates mismatch. This, in turn, makes the decision-making process more objective and fast. The effectiveness of the proposed modification of the analytic hierarchy process is compared by the example of decision-making on the selection of coating metal taking into account physical, mechanical, economic, environmental and technological factors. For the example under consideration, the expert was excluded from 180 comparisons. | ||
Nizametdinov F. R., Sorokin F. D. Euler vector application specifics for large turns description while flying vehicles structural elements modeling on the example of a rod finite element. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/ae3/Nizametdinov_Sorokin_rus.pdf Structural elements in mechanic engineering are often may be reduced to a rod model, characterized by large generalized displacements with small deformations These elements are, for example, propeller blades, outer wing spars, etc. [1-4].
Many works have been devoted to the problem of describing the large displacements of structural elements represented by rod models. For example, a wide class of methods is based on the use of systems of differential equations [5-10]. At the very beginning of computational mechanics development, the method of representing elastic bodies by a set of solid elements was used, and the elastic properties of deformed bodies were modeled by elastic bonds [11-13]. Attempts were made to combine the solid-state modeling with the finite element method (FEM) [14]. According to this method, the total displacement is a sum of independent large rigid displacement and small elastic displacement due to deformations [15]. The next step was the method of successive approximations, which was modified to the method of the attached coordinate system. But this method was not widely used due to the appearance of more advanced approaches, such as the method of absolute nodal coordinates [16-18]. This formulation is the most complete, but at the same time is very complicated for performing out practical calculations [19]. In [20], the asymmetric Piola-Kirchhoff tensor is used. In [21], the position of the FE cross-sections is given by the radius vector and two ortas. Such approach increases the number of kinematic parameters, but allows avoiding singular points.
In [22], the FE is constructed using an independent description of displacements and rotations by Hermite polynomials, which leads to the problem of shear locking. In [23], the quadratic approximation of the tensor elements ro`tation is used. In [24], the vector-tensor theory of large rotations is used, but the magnitude of the rotations is restricted by the angle of 2π radians. In [19], the Craig-Bampton method is used.
A widespread approach to the geometrically nonlinear beam FE construction is the co-rotation approach [25]. In [26], a co-rotational FE is considered, in which the hypothesis of the relative strain smallness is built-in. The disadvantage of this element is the presence of singular points at the rotation angle of 2π. The model [27] had no such shortcoming due to introduction of an intermediate position. But it is considerably more complicated due to application of the nonlinear theory of elasticity apparatus. An incremental description of the rotations was also used in the element proposed in [28] in application to the problems of multi-body dynamics. Such a variety of approaches is explained by the presence of more than a dozen methods of large rotations describing [29-31].
The most common and natural way to describe finite rotations is the Euler vector [6, 32-34]. However, the Euler vector has a disadvantage, namely, critical value of the rotation angle (2π). At this value of the rotation angle, the tensors connecting small physical rotations with derivatives of the kinematic parameters become degenerate. The article considers two modifications to overcome this problem. These modifications allow describe infinitely large rotations. Their comparison is performed on the example of the rod FE. The features of both modifications are described in the paper. The tangential stiffness matrices and the node-force vector of the rod FE were obtained in a closed analytical form, with account for these features. The solution of test tasks by two approaches, analysis of the program code allowed reveal the advantages and disadvantages of both modifications.
The modification based on the adjustment of the Euler vector when the critical rotation value is reached is extremely simple for implementation, and correction is not required at every step of the solution. This modification can be integrated into the FEM package without significant changes in its architecture. Disadvantages of this modification are as follows: sudden change in the Euler vector when the critical value is reached, and asymmetric stiffness matrix.
The incremental way of description is not free from such shortcomings as the sudden change in the Euler vector, an asymmetric tangent stiffness matrix. But this modification is much more difficult for implementation and requires completely different system of storing the results. In addition, the architecture should provide the possibility of combining incremental and non-incremental elements.
Modifications are considered on the example of a rod element, but without significant changes they can be extended to other two-node FEs, such as FE farms, FE springs, FE rigid constraint, etc. | ||
Pogosbekian M. Y., Sergievskaya A. L., Kroupnov A. A. Comparative modeling of N2 molecules dissociation in thermally non-equilibrium conditions. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/6ea/Pogosbekyan_Sergievskaya_Krupnov_rus_.pdf At strong shock waves in rarefied gases, chemical processes such as dissociation and exchange reactions occur in conditions of thermodynamic non-equilibrium, and the rate coefficients are the functions of both translational—rotational and vibrational temperatures.
The object of the study are chemical reaction models of the of N_{2} molecules dissociation occurring in thermally non-equilibrium conditions.
The goal of the work consists in comparative study of physico-chemical processes models on the example of dissociation of nitrogen molecules. For comparison, the well-known and frequently used theoretical dissociation models, representing the process in a single-temperature, two-temperature, and level approximation, were chosen. The article presents a detailed description of theoretical models allowing calculate the goal functions of the N_{2} molecule dissociation models in thermally non-equilibrium conditions, both in the two-temperature and in the level approximations. To perform a valid and reliable comparison, in addition to theoretical models, the results of molecular dynamics of N_{2} molecules modeling obtained by the classical trajectory method, as well as data from a physical experiment on a shock tube are used.
To simulate molecular dynamics, the computer “MD Trajectory” complex was used. Computational experiments with theoretical models were performed in the environment of the Internet Catalog of physical and chemical processes models.
A new functional, depending on the translational temperature and expression for the empirical parameter of the Marrone-Treanor model was proposed based on the comparison. The modified model application allows describe the results of trajectory calculations in a wide range of translational temperatures from 2000 to 10000°K. | ||
Fedyushkin A. I., Puntus A. A. Nonlinear features of laminar liquid flows on Earth and in microgravity. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/1eb/Fedyushkin_Puntus_rus.pdf The article presents the numerical modeling results of hydrodynamics and heat and mass transfer and discusses the non-linear features of laminar flows. It considers numerical simulation results of hydrodynamics and heat and mass transfer and discusses the laminar flows features at moderate Rayleigh and Reynolds numbers in the following problems:
The results based on the numerical solution of the Navier-Stokes equations for a viscous incompressible fluid for flow regimes studying in a flat diffuser with a small angle and opening are presented. Flow regimes transition in a diffuser from a symmetric stationary regime to asymmetric stationary one and then to asymmetric non-stationary regime in their dependence on the Reynolds number is demonstrated. The values of Reynolds number defining the ranges of a given regime existence are pointed out.
The impact of controlled vibrations on the heat-mass transfer and, in particular, on temperature boundary layers in the melt for crystal growth processes were studied. Analysis of the controlled vibrations effect on hydrodynamics and heat-mass transfer for the microgravity and normal gravity conditions was performed. The of numerical simulations results revealed that vibrations can enhance heat and mass transfer and mix the melt, as well as reduce dynamic, thermal and concentration boundary layers. Vibration can also increase the temperature gradient of the solidification front, which, in its turn, can increase the rate of crystal growth. The numerical simulations results demonstrated that vibrations can make the crystallization front shape flatter.
In zero gravity, while lateral heating of the two-layer system “air-liquid” in the volume with free walls, the interface due to thermo-capillary convection and small perturbations can be rotated by 90° and assume a stable position parallel to the heated wall.
Gravitational convection (even in the presence of thermocapillary convection) is a stabilizing factor for the horizontal position of the interface. | ||
Krovjakov V. B., Korolenko V. V., Stepanov R. N., Greshnov A. S., Rachkov P. V. Problematic questions of unsteady liquid flows modes organizing while liquid systems cavities cleansing. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/99a/Krovyakov_Korolenko_Stepanov_Greshnov_Rachkov_rus.pdf While performing studies in the field of improving technologies and equipment to ensure the required level of LHC induction chambers working cavities, it was found that hydrodynamic methods are the most effective from the viewpoint of quality and economy, and among them the washing method employing the unsteady fluid flow modes organization with optimal for each purification facility modes of pumping . Its disadvantage consists in the dependence of the pressure intensity and velocity oscillations, and, consequently, cleansing efficiency from the purification object design features and its geometric parameters. As the cavity being cleansed moves away from the source of vibrations their intensity decreases.
The results of the performed study allowed develop technical solution on the hydro-pulse cleansing of the HHS working cavities technology consisting in the fact that according to conventional cleansing technology by pumping through the internal cavities of the cleansed object in the unsteady mode. This unsteady mode is being created by the fluid flow rate changing from 0 to the value determined by the fluid pressure, not exceeding the pressure for the part being cleansed. A periodic change in the fluid flow rate in the maximum possible range, determined by the specified pressure, corresponds to the periodic change of its speed in the maximal possible range also.
Thus, the maximum possible velocity oscillations amplitude is reached, determining the flow degree of turbulence, tangential frictional stresses magnitude on the surface being cleansed, and other factors affecting the of contaminants breaking-off and removal intensity. In the process of studies, technical solutions on the proposed technology implementation were also developed.
Due to the insignificantly small fluid compressibility, all manipulations with its volumetric feed (and thus with speed) at the inlet of the product to be cleaned undergo infinitesimal changes as they move along the cavity of the product up to the outlet from it (unlike the pressure oscillations created by the change in the areas of the passage section). Hence, the cleansing liquid unsteady mode retains its maximum cleansing ability in all areas of the cavity being cleaned. | ||
Khatuntseva O. N. On the Occurrence Mechanism of of the Random Value with the “Heavy” Polynomial “Tails” in the Stochastic Processes of Gaussian Distributions. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/063/KHatuntseva_rus.pdf Most of the economic, biological, physical and other processes are adequately unpredictable. The lack of the determinism in such stochastic processes is related not only to probability distribution of the considered process possible realizations of the, but also with the possible unsteady behavior of the probability density. Stochastic process may gain the additional uncertainty if the probability density of the random value realization can be described at random fr om the set of the feasible functions describing it.
The article considers the problems related to the possible of the probability density non-uniqueness of the random value realization in stochastic processes. It shows that the method for the stochastic processes description for the systems with no selected equilibrium states allows find different probability densities for the stochastic process that may realize at random way the certain range of random values.
In this respect, the following conclusion based on the Lindeberg Central Limit Theorem can be made. The Gaussian distributions with “heavy tails” manifestation may be considered as the consequence of the hidden factors occurrence in the system, affecting the probability density dynamics when random value realization of the considered process causes the variation of the probability density of realization. It confirms the prognosing feasibility of natural and technogenic catastrophes based on the considered random values distributions analysis from the viewpoint of their deviation from the normal (Gaussian) law of distribution. In hydrodynamics, such deviation indicates the appearance of the coherent structures and the possibility for the transition form the laminar flow mode to the turbulent one.
The phase space dimensionality analysis allows determining both stable and unstable branches of the solution for the probability density in such random value realization domains, wh ere a unique solution may be realized. | ||
Firsanov V. V., Vo A. H. The study of the longitudinally stiffened cylindrical shells under action of local load by the refined theory. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/dd4/Firsanov_Vo_An-KHieu_rus.pdf At present, engineering calculations of ribbed shells are based on the results of the classical theory of Kirchhoff-Love and Timoshenko-Reissner type. The hypotheses adopted in this theory does not allow accounting for the shell transverse deformations, leading to the errors in the determining the stress-strain state (SSS). It forces to develop increasingly advanced methods for SSS calculating with account for the distortion zones, including those near the joints of structural elements, as well as local loading.
The purpose of this article consists in developing a refined version of the theory of the SSS calculating of longitudinally stiffened cylindrical shells under the impact of radial axisymmetric local load.
The shell displacements are approximated by high degree polynomials with respect to the classical theory of Kirchhoff-Love and Timoshenko-Reissner type. Basic equations and boundary conditions obtained by the minimum total energy of deformation principle are presented. The boundary value problem solution is performed by operational method based on the Laplace transform.
The results obtained in this article allowed establish that the with the ribbed shell calculation by the refined theory there were always rapidly damped additional edge stress states of the “interface” type. Near distortion zones of the stressed state, the transverse normal stresses, neglected in the classical theory, were obtained of the same order with the maximum values of the basic flexural stress. Moreover, for the thicker shells the transverse normal stresses contribution to the total SSS increases significantly. | ||
Kuruliuk K. A. Videogrammetry system for contactless measurements of large-size objects deformation fields. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/277/Kurulyuk_rus.pdf Large-size engineering objects under operation are subjected to various stresses, leading to considerable deformations. Normal functioning, strength and safety of such objects is achieved through thorough studies and testing, in which methods and tools for measuring geometric motion and deformation parameters play an important role. Particularly, in recent years, the problems of deformations measuring of aircraft large-sized models and structural elements arose. One of the promising measuring methods for solving this type of problems is optical method of videogrammetry (VGM), combining modern means of optics, digital image recording, numerical image processing and mathematical analysis. High information value of the VGM method is stipulated by the fact that one image allows getting information on hundreds and thousands of points of an object simultaneously. At the same time, it was necessary to create a mobile measuring system which would not be associated with particular experimental installation or wind tunnel, and which could be quickly applied in different conditions to measure deformation of full-scale aircraft elements while their ground testsand in flight.
The purpose of this work consists in improving videogrammetry method and developing a mobile measuring videogrammetry system (VGM system) to ensure non-contact measurements and visualization of distributed deformations of large-size objects in engineering, as well as expanding this method’s application area. A step-by-step measuring technique employing one digital camera was stated and developed. A two-stage of a measuring system calibration technique was developed.
Control tests of mobile VGM system sample were carried out for measuring deformations of natural wing of a new transport aircraft sample under operating test bench conditions during industrial ground life tests. The maximum measurements distance was of 26 m. The root-mean-square error of normal deviations of points did not exceed 2.5 mm.
This work was performed within the framework of the “Development of mobile videogrammetry measuring system for operational non-contact measurements and visualization of distributed deformations” Project according to the Grant from Moscow Region Government in the fields of science, technology and innovation. | ||
Vyatlev P. A., Goncharov K. A., Sigaev V. N., Sysoev V. K., Yudin A. D. Glass elements fabrication technology analysis for space elements thermo-optical covering. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/024/Vyatlev_Goncharov_Sigaev_Sysoev_YUdin_rus.pdf A spacecraft (SC) thermal conditions ensuring is associated with thermo controlling coating selection. The coating type of the «solar reflectors» class is intended for application on the radar surfaces, ensuring extra heat removing into surrounding outer space in conditions of these surfaces’ contemporaneous irradiation by the Sun. The K-208Cp thermoregulation coating represents the plates of optically transparent glass K-208 of 150 ± 20 microns thickness with sizes of 20×20 mm, 25×25 and 40×40 mm, with electrically conductive coating on one side and silver and stainless steel layers on the other side, successively applied in vacuum. These plates are glued to the hull by the metallized side. The article presents the system analysis of fabrication of the glass elements for this coating.
Glass elements require several stages of manufacturing technology. The article describes all stages of production. High demands are placed on the glass elements geometric parameters. They are the plate sizes, glass elements quality and flatness fault. Long-term studies helped to establish the optimal temperature regime at which the change the glass elements shape does not occur.
The cycle of manufacturing technology includes chemical hardening processes. The main problem of application of glasses is their weak mechanical strength. A simple and effective method of the glass plates hardening is the method of low-temperature ion exchange. | ||
Zagidulin A. R., Podruzhin E. G., Levin V. E. Modeling a motion of a non-free system of rigid bodies in the case of calculating damping of the light aircraft landing gear. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/c68/Zagidulin_Podruzhin_Levin_rus.pdf The article describes the mathematical model of the light aircraft landing gear using the method of modeling the motion of a system of rigid bodies with holonomic constraints based on Lagrange equations of the first kind. Traditionally, in design practices for calculating the landing gear damping, Lagrange equations of the second kind are used in generalized coordinates. The disadvantage of this technique is that for each kinematic scheme of landing gear it is necessary to make up its own system of equations, which is a very laborious process. To solve this problem, it is advisable to use a technique based on Lagrange equations of the first kind, which makes it possible to formalize the process of composing equations of motion of a non-free system of rigid bodies. This approach allows us to represent the aircraft landing gear model in the object form – as a set of objects: rigid bodies, power factors and mechanical constraints, which ensures the modularity and extensibility of models.
For the landing gear presented in the article, constraint equations in joints of the construction are written. Expressions are given for the determination of active forces: axial force in the shock absorber, the force of compression of the wheel’s pneumatic. Results of numerical simulation of landing impact are presented in the article.
The method used in calculating damping of the aircraft landing gear differs from methods of calculation previously used, primarily universality. When the system of rigid bodies changes, there is no need to rewrite the equations of motion in generalized coordinates, only the dimensionality of the system changes, and the form of equations is unchanged. Such a universal approach is more algorithmic and simple in numerical implementation. | ||
Rebrov S. G., Golubev V. A., Golikov A. N., Morgunov A. E. Experimental studies of oxygen-hydrogen and oxygen-methane fuels laser ignition in the ignition device by a semiconductor laser. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/3d2/Rebrov_Golubev_Golikov_Morgunov_rus.pdf The article describes the results of experimental work on the laser ignition of oxygen-hydrogen and oxygen-methane fuels in the ignition device. In the course of the studies, a semiconductor laser with the fiber output of radiation, which main designation consisted in its utilization as a radiation source for solid-state laser pumping, based on active YAG: Nd medium, was employed as the ignition energy source. While experimenting, the fuel mixture ignition resulted from the optical breakdown spark when laser radiation was being focused near the target surface located in the ignition device reaction cavity.
The main task of the experimental work was determining the fundamental possibility of semiconductor lasers application for the studied fuel mixtures ignition. Positive results of the experiments on both oxygen-hydrogen and oxygen-methane mixtures ignition at the maximum output energy parameters of the laser employed allowed proceed to the second stage of the study on determining the impact of the laser source and the ignition device operating characteristics changes on the possibility of both fuel pairs ignition. As a result, the data was obtained on the operating ranges of the output energy and laser pulse-repetition frequency, as well as consumption and excess coefficient of the oxidizer for the studied fuels, determining stable laser ignition.
In the course of the work carried out, the possibility of rocket fuels laser ignition from a semiconductor laser with a fiber output was demonstrated, which application will reduce the requirements for thermal stabilization and facilitates the vibration isolation of the ignition system when placed on board a spacecraft. | ||
Baklanov A. V., Vasilev A. A. Adaptive technologies application in the issue of studying the flow structure formed by the burners in the GTE combustion chamber. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/f56/Baklanov_Vasilev_rus.pdf In conventional practice, ensuring the necessary parameters of combustion chambers is achieved by studying several options of swirl burners to obtain the optimal design, acceptable for the combustion chamber. The swirl burners’ production is a labor intensive and expensive process. Modern additive technology application for the parts manufacturing is actually the technology allowing produce shortly the burner with necessary design and test it, obtaining the parameters of interest to the developer.
The article presents the result of designing and producing combustion chamber burners of gas turbine engine by the prototyping method. Printing of burners was performed with 3D Picaso printer, which operates by the plastic extrusion technology. In other words, the burner model is fabricated by layer-by-layer applying of extra fine layers of molten plastic. These layers, becoming a virtual cross-section in CAD model, are united or fused together to form an object of the adjusted form. The ABS and PLA plastics, which allowed machining, polishing and painting, are used for printing. Several burners with different blade angles were produced. The article presents the equipment and materials being used for the burners producing, the design of test bench, which was used to study the flow pattern in outlet of the produced burners.
Based on the performed studies, it was discovered that the near placed burners with various swirl directions of blades formed the short structure of turbulent jet. It is explained by mutual penetration of turbulent layers directed towards each other As result, the vortex energy content scale of is decreased as the jets energy is spent for collided layers interaction. The authors conclude that in modern low-emission combustion chamber the short residence time of gases of about 7 ms is provided. It is necessary to reduce the level of nitrogen oxides formation in combustion products. Thus, organizing the opposite twist between the burners in the upper and lower stages is may be useful to ensure the low-emission combustion. | ||
Khramin R. V., Kikot' N. V., Lebedev M. V., Burov M. N. Design procedure for heat dissipation of hybrid bearings with grease lubricant. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/ecc/KHramin_Kikot_Lebedev_Burov_rus.pdf Grease-lubricated bearings application is a promising trend for weight reduction and reliability increase of small-size engines, which allows eliminate the oil system utilization. Since the lubricant grease working temperature is, as a rule, lower than the temperature of conventional aviation oils, accurate assessment of the bearing thermal state is required. To reduce heat generation within the bearings under study, ceramic rolling elements, rather than traditionally used steel bodies, are used. The bearing lifespan is determined by the loads and thermal state of the bearing elements and grease. To determine the bearing thermal state, we are to know the values of heat flows affecting the bearing. Heat flows from the surrounding parts and air can be sufficiently determined by the verified commercial software products. To determine the heat flow generated by the grease-lubricated bearings, it is required to create and verify a design procedure, as there are no branch calculation methods for heat generation of grease-lubricated bearings. It will be impossible to justify performance of the engine, equipped with such bearings, before the certification body without the verified heat- generation calculation method for grease-lubricated bearings.
The article presents the design procedure for heat emission of hybrid grease-lubricated bearings with ceramic rolling elements. The computational experimental Demidovich’s method is used as the main criterion equation. The Demidovich’s method is distinguishes from the other bearing heat-emission computation methods by availability of the similarity theory elements, as the main criterion equation uses of the bearing geometry features. That is why the dependencies defined by this method represent flexibility for the studied bearing size. The experimental data for the design procedure verification were obtained during the tests of the angular ball bearing size 126308. The coefficients describing the experimental data with enough engineering accuracy were determined due to the analysis. The heat flow calculated in accordance with the presented design procedure can be automated and built in the bearing 3D-model together with the heat flows from the bearing environment. | ||
Starovoitov E. I. Laser ranging systems characteristics for unmanned aerial vehicle strapdown inertial navigation system. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/748/Starovoytov_rus.pdf Further development of unmanned aerial vehicles (UAV) includes the onboard navigation systems improvement. It is associated with broadening the tasks, performed by advanced UAVs: increasing autonomy fr om the human operator, increase in speed, radius of action, flight time and altitude range
The article studies characteristics of laser ranging systems (LRS), intended for error correction of the strapdown inertial navigation system in the UAVs onboard navigation systems. The author considered the LRS structures based on 3D Flash Ladar-technology and optical-mechanical scanners (OMS) of conventional and hybrid types.
Either Diode-pumped solid-state lasers (DPSSLs), ordiode lasers and fiber lasers can be employed in LSR. Avalanche photodiodes (APD) and PIN photodiodes can be employed for the reflected signal receiving.
The article analyzes the OMS performance. The maximum UAV’s flight speed, on which the LRS with OMS operates, is determined of the ratio of the angular resolution to the angular size of the field of view. Maximum range of LRS measurements is primarily determined by scanning speed and laser pulses’ repetition frequency, and secondly by the power of laser pulses. To expand the speed range, wh ere the conventional type of OMS can be employed, it will be necessary to narrow its angular field of view. In the same flight range of altitudes, the maximum permissible flight speed for hybrid type of OMS will be higher by an order of magnitude.
APD and PIN photodiodes can be implemented in 3D Flash Ladar systems (in which case the maximum range of measurements is reduced by an order of magnitude, as well as increase in the receiving aperture is required).
Traditional type of OMS, based on fiber laser, can be applied for operation in the range of altitudes from 0.4 to 2.0 km (from 0.2 to 1.2 km when PIN photodiodes are used) and flight speeds to 850 km/h.
Hybrid type of OMS, based on fiber laser and APD, can be applied for operation in the range of altitudes from 0.2 to 1.0 km and flight speeds up to 1300 km/h.
Characteristics analysis of of all three LRS types revealed, that the most promising was LRS structure based on hybrid type of OMS, having the highest efficiency. This structure employs fiber laser and APD.
The results of this work can be used while developing the onboard navigation systems for advanced UAVs. | ||
Agishev A. R., Kasatkin V. G. Corrections planning for a spacecraft Low-Thrust Geo-Transfer. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/782/Agishev-_Kasatkin_rus.pdf After the spacecraft (SC) is put into geostationary orbit (GEO), its longitude may differ from the longitude of the stand point. The initial deviation of longitude may be of several tens of degrees, while the period deviation corresponds to the larger speeds of a SC drift along the orbit. The plan of deployment correction, including information on the initial time, corrective action duration and direction, that change the orbit period and eccentricity, is required to set the SC into stand point.
The purpose of the work consists in developing a high-speed algorithm for GEO transfer plan computing.
The existing methods of transfer employ complex control optimization methods, requiring extra memory and computational resources. Their application onboard the SC is not always possible due to the limited computing resources. Another group of methods uses analytical calculations of the correction plan, but their application is impossible in practice due to the actual space systems’ limitations.
In the proposed method, the correction plan is computed while simulation process. Computing is performed in a cycle by control intervals. One iteration contains testing of the simplest logical conditions and flight simulation at the current control interval. The control interval duration is equal or greater than 24 hours by the correction value by the current 24 hours.
A distinctive feature of the proposed method is the optimal dependence between longitude and orbital period. If the spacecraft deviations match this dependence, the spacecraft would be set into nominal GEO longitude by these daily period corrections.
The algorithm workability was verified for 1000 GEO transfer computations from different initial orbits. The final deviations of the longitude after the maneuver are acceptable for spacecraft station-keeping.
The efficiency of the method was being checked by comparing deviations of longitude and period, as well as maneuver duration and the characteristic speed with the calculation by a well-known method using difficult, resource-intensive algorithm of GEO transfer. The comparison results revealed the proposed algorithm effectiveness, and the relative simplicity of calculations by the method and characteristics of the maneuver give it an advantage in the computations onboard of the spacecraft. | ||
Us N. A., Zadorozhniy S. A. Model of noise and instability sources of a ring monoblock gyro. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/99c/Us_Zadorozhniy_rus.pdf Various systems operating on different physical principles are applied as gyroscopic sensors of modern high-precision aircraft strapdown inertial navigation systems. The most widespread in the world are laser gyroscopes implementing the Sagnac effect and differing in design and technological versions. Commercially available inertial navigation systems employ two types of such gyroscopes: ring gas and fiber-optic. Relatively recently, a novel design, occupying an intermediate place between ring gas and fiber-optic gyroscopes, appeared in the group of laser gyroscopes. This unit was called a “ring monoblock gyroscope with the semiconductor laser diode”. The vital difference of this unit consists in the presence of the polyhedral optical monobloc with the triangular optical scheme with open channels, placed inside the unit. The problem of the bidirectional optical signal formation form the laser diode is solved by the original resonator-splitter design. With this, the semiconductor laser diode is placed inside the gyroscope optical scheme. The ring mode of the optical signal is realized by the mirror system. Information retrieval about the navigation object angular velocity is performed by dynamic interference pattern processing from the gyroscope output. The new design and technological solution of the gyroscopic sensor requires its error knowledge based on the corresponding generalized noise and error sources mathematical model. The article examines the triangular optical monoblock diagram of a laser gyro with high symmetry relative to the axis “resonator-beam splitter – interference mixer – photo detector” to evaluate potential noise and instabilities. This optical scheme was not analyzed earlier due to the fact that the ring gas laser gyroscopes were unclaimed. Estimates of the given design and technological solution potentialities as a sensitive element of the aircraft inertial navigation system were obtained. The article demonstrates that the optical system possesses the internal mutual phase modulation presence, and compensation of the internal temperature gradients of the object under study exists as well. The developed structure of the ring monoblock gyroscope is recommended as high precision, thermally stable ring monoblock gyroscope with laser semiconductor diode for the aircraft strapdown inertial navigation systems. The design and technological solution specifics of the sensor may be the basis while solving the problems on sensitive elements of the inertial navigation system backing-up. | ||
Kondratenko V. S., Rogov A. Y., Kobysh A. N. A new approach to hydrocarbon liquids leakages control onboard an aircraft. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/1b8/Kondratenko_Rogov_Kobysh_rus.pdf The article considers a new approach to control of leakages from the aircraft fuel and hydraulic systems in flight, implemented based on sorption sensor cable sensitive to hydrocarbons. It shows that the traditional methods of aviation fuel leakage and hydraulic system working fluid (aviation oil) control, based on computational algorithms, have significant drawbacks, namely, a time delay of leakage detection and inability to determine quickly its location. The authors propose an alternative solution to these problems, i.e. gravity independent sorption cable hydrocarbons sensor (SCHS) highly sensitive to the hydrocarbon liquids. Sorption mechanism of interaction with the liquid leakage, ensuring its high sensitivity, allows placing the SCHS directly on the elements of the aircraft fuel and hydraulic so as to ensure the ingress of liquid on the sorption sheath of the cable regardless of the possible directions of leakage. If this condition is met, the liquid leakages detection can be performed at any aircraft position in space, including active maneuvering, which significantly expands the range of the aircraft with the SCHS leakages control application. The unique SCHS sensitivity and speed allow considering it as the basis for the onboard automated systems for early leakages detection in the aircraft fuel and hydraulic systems. While developing leakages detection systems for leakages locations determining, a zone method with assigning a separate cable for the controlled object, or reflectometry method while organizing control at extended object can be employed. | ||
Arevshatyan E. S., Pavlova N. V. The first step of the automated training system. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/1a7/Arevshatyan_Pavlova_rus.pdf The article presents the students testing system model developed using the expansion and addition of the classical methods of knowledge assessment of the students. It is applicable for effectiveness analysis.
It is applicable for the effectiveness analysis of mastering of the passed through material, both by students and tutors. The system is realized based on the client-server architecture using basic web client templates and a server part of Apache. It is developed as the first step of automated information processing system with developing structure.
It was required to develop the first step of the developing automated system of the university training of the students mastering the program of disciplines for the specialties, associated with aircraft onboard equipment development. At this stage, the tasks of development of the program and algorithmic provision were set and solved. They allow:
Due to the structure selection and used software the system is implemented as the developing automated system and intended for operation within the network using of client-server architecture, based on the JavaScript programming language and the Apache server, and MySQL databases
Method of written tests supplemented with further mastering of materials at the conceptual level is used in the first stage of system.
The results on the program development and algorithmic provision for the first stage of the developed automated training system are presented.
The system imitation model with two levels of data access (the teacher and students) and two levels of didactic material granting is developed both in the form of tests and in the form of the text.
It is advisable to consider also application of the kernel of the created system for developing various training systems for operators of commercial unmanned aerial vehicles. | ||
Kovalsky A. A., Zinnurov S. H. Models and algorithms for a communication spacecraft dynamic radio resource backing-up while servicing non-stationary information streames with account for delay in control. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/aff/Kovalskiy-Zinnurov_rus.pdf The goal of operative satellite repeater’s radio resource distribution (reservation)is set as the nonlinear programming problem, and the example of its solution while servicing a non-stationary message stream formed by the group of voice subscribers is given.
Modulated Markov process and its special case, called interrupted Poisson process are used as a model of non-stationary message stream formed by voice subscribers, with account for signal suppression during pauses. Modulated Markov process mathematical model of a servicing process with the time lag while of additional channels connection was developed as a three-dimensional Markov chain. Algorithm of this problem solution was developed, and the example for the case, when the ingress flow was being formed by only one subscriber, is presented.
The object of the study is channeling equipment of a ground station of a communication satellite, which employs a communication spacecraft for the channels radio resource organizing. An object of the study is a technology of backing-up a communication spacecraft radio resource. The research objective is directed to the capacity growth of the ground station of satellite communication, due to the choice of optimum value, the backed-up radio resource for each direction of communication.
The simulation model of dynamic back-up of a communication spacecraft radio resource, based on the software product recommended for performing scientific research in the field of mathematical and simulation modeling, namely Matlab/Simulink/SimEvents, together with the interactive building tool for complex Stateflow models was developed and described. The Stateflow software product based on the theory of finite state machines and queuing systems application is intended for logical queuing systems design.
The developed approach to managing of communication satellite’s limited resource distribution, allows achieve substantial advantage savings (about 30%) of the communication satellite radio resource, due to its dynamic redistribution between the radio communication directions. | ||
Zanin K. A. Developing a model of space radar bistatic interferometer basic parameters. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/704/Zanin_rus.pdf The article introduces a mathematical model of basic parameters of the bistatic space interferometer with two synthetic aperture radars. The space interferometric survey consists in obtaining a digital model of the terrain relief. Bistatic (tandem) interferometric survey implies simultaneous operation of the two spacecraft. In this mode, two synthetic aperture radars form interferometer defining the phase difference of the signal incoming from the Earth surface. However, high accuracy of defining space vehicles position and phase stability of the radio electronic path is required.
At present, several commercial digital relief models exist in the world. The most complete in coverage and best in accuracy is the DLR model obtained by “Terrasar-X” – “Tandem-X” spacecraft in bistatic mode of radar operation.
Relief height definition in bistatic interferometric mode requires minimum amount of a priori information, though it requires high accuracy of defining space vehicles position and phase stability of the radio electronic path.
The article analyses selection of the interferometer basic parameters with account for the requirements of the relief height determining accuracy. The impact of position determination errors of space vehicles in space on measurement errors is being evaluated. As an example, the analysis of the requirements to navigational and ballistic provision of interferometric tandem spacecraft “Terrasar-X” and “Tandem-X” is presented. | ||
Khrustaliov M. M., Khalina A. S. Identifiers of reduced dimension in the problem of the unmanned aerial vehicle stabilization in perturbed atmosphere. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/de1/KHrustalev-KHalina-rus.pdf Unmanned aerial vehicles (UAVs) have taken their rightful place in modern activities. The UAV control processes improvement is undoubtedly actual and allows employing more and more unmanned robot-vehicles.
The article considers the problem of a small UAV horizontal flight stabilizing in the vertical plane with account for angular motion. Due to the UAV smallness, the wind should be taken into account, and the control system should ensure high stabilization quality while being simple enough.
Stochastic quasilinear system was selected as a model for the control process description with account for the wind, as accounting for the ongoing processes most adequately, but, at the same time accessible for the effective analysis. Vertical and horizontal components of the wind disturbance are set by the modified Dryden-type generating filters
The authors suggested to employ minimum number of measured motion parameters to simplify the stabilization system.
Since that it is not always possible to stabilize the system by a limited set of state vector components for control, it is conventional to use the state identifiers. However, there several problems exist herewith. The generally accepted in practice formulation the problem of optimal control synthesis is based on the separation theorem. According to this theorem, the optimal control consists of an optimal filter, forming an estimate of the state vector, and optimal regulator determining the control under the assumption that the state vector is known exactly. The result of this theorem is strictly proven for linear systems only. As for the quasi-linear systems, to which the considered system is referred to, the separation theorem is inapplicable.
The presented paper proposes a natural approach to the joint synthesis of the control srategy and the identifier. In this case, the authors propose selecting both the control strategy parameters and the identifier parameters from the condition of the general stabilization quality criterion minimum. The proposed method feature consists in the absence of control and observation synthesis problems separation.
The general method for solving problem of optimal quasilinear stochastic system synthesis to find optimal control strategy in the presence of incomplete information on the system state vector was used. This method was earlier developed by the authors. It includes the necessary optimality conditions and the numerical method of the gradient type. | ||
Lisov A. A., Chernova T. A., Gorbunov M. S. System approach to the degradation processes in electrical devices. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/f7d/Lisov_CHernova_Gorbunov_rus.pdf The presented work considers a system approach to the electric devices reliability and operating efficiency enhancing, ensuring faultlessness by forming the information computer system for analysis, modeling and evaluation of electronic devices degradation state, as well as their diagnosing and forecasting theiremr residual resource forecasting according to the simulation results. It is especially actual in aviation using such devices.
The closest prototype in relation to the system of failure prevention in technical systems being developed are the already formed and recommended approaches based on methods for complex technical systems faultlessness provision. The closest prototype on analysis and faultlessness provision of electric motors are the developments on electric motors reliability by of O. Goldberg School.
The presented work suggests the degradation deviations of stator phases voltages, and functions of rotor mechanical oscillations in the run-down mode while power supply turning-off as characteristic parameters. Information content of the induction motor characteristics in the run-down mode while supply circuit turn-off was established relatively to the subject of research. Criteria of the induction motor stop and its removal from service were established.
The system approach to the degradation processes analysis of electric devices allows:
The electric devices operation efficiency is determined by the “individual tracking” of each object from the industrial batch, operating in concrete conditions with its own “individual” modes history, ensuring optimal resource, intervals and terms of check test, excluding remove from service of the still fit products. | ||
Nuriev M. G. Physical simulation of an unmanned aerial vehicle electronic means noise immunity. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/e83/Nuriev_rus.pdf An important factor affecting the safety of unmanned aerial vehicles is the impact by the electromagnetic field of a remote lightning discharge. Powerful external electromagnetic fields may lead to the of noise immunity disturbance of on-board electronic systems. Particularly in recent years, a trend towards the unmanned aerial vehicles development with a fuselage made of nonmetallic materials with low efficiency indicators for electromagnetic fields shielding gains momentum. Based on the technique of physical modeling of electromagnetic interference in electronic communications lines under the impact of electromagnetic fields, the problem of predicting the noise immunity of an unmanned aerial vehicle electronic means under the impact of a remote lightning discharge is realized. Physical modeling is a method of experimental study of various physical phenomena, based on their physical similarity. Computation of all the stages of the method of physical simulation of electromagnetic interference was performed. The imitation and measurement equipment was chosen. A test bench and a model of the studied object were developed. The article presents an example of physical modeling of electromagnetic interference in electronic systems’ communication lines of an unmanned aerial vehicle under the impact of a remote lightning discharge. To predict the noise immunity of the onboard electronic systems of unmanned aerial vehicles, it is necessary to compare the parameters of electromagnetic interference in communication lines with critical values, leading to a temporary functioning disruption or sensitive elements damaging. The noise immunity forecasting of an unmanned aerial vehicle electronic elements under the impact of electromagnetic interference of a remote lightning discharge was performed. When detecting possible noise immunity failures of the onboard electronic systems, it is necessary to take already known as well as new measures to reduce the interference in advance. | ||
Zinchenko A. A. Weight control organizing while aircraft engineering production. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/8b8/Zinchenko_rus.pdf The experience shows that theoretical weight calculation does not often match weighing results. This statement holds for parts and assembly units made by casting and die molding from rolled metal and composite materials. This includes also electrical equipment and harnesses which weight is about 9% of total aircraft weight. It is difficult to account for paint coating put on aircraft parts, as well as sealants ensuring junctions seal.
Untimely transfer of parts and assembly units weighing results to design bureaus is followed by organizational difficulties of internal weight control in production. The internal processes analysis of various organizations allowed creating a working model of weight control automated system at PJSC AAC “PROGRESS”. The company standard and “Weight control” software developed with C++ programming language and Oracle database is used as a basis for weight control automated system.
Putting weight control automated system into operation has significantly shortened searching and processing time for parts and assembly units weighing control and documents writing.
The weight control automated system developed at PJSC AAC “PROGRESS” is a significant move on the way to internal production processes automation. It possesses a high potential of further development. For example, the weight control system could be supported by the following:
– A server with the data field (cloud), accessible to all the participants, working with weight control;
– Calculation methodology of aircraft parts and assembly units at the design stage, which, for example, will include NeuroWorks [1] software developed on the principle of artificial neural network. The program uses exploratory-dependent formulas, therefore it might use weight control automated system’s weights database;
– Cooperating enterprises involvement into weight control automated system. This will accelerate data submission on parts and assembly units to aircraft designer;
– Parts and assembly units identification by their direct marking [2] (barcode numbering, FRID), this will allow tracking parts and assembly units throughout the aircraft life cycle in a better way;
– Modern weight control means allows entering information on parts and assembly units, such as weight, time, date, photo, overall dimensions, into the database;
– The terms for synchronizing weight control automated system and CAD, CAE systems . This will allow eliminate input of parts and assembly units points for aggregates center of mass determination of the whole aircraft and use actual values of distributed loads when estimating aircraft configuration in CAE systems;
– Accounting for the aircraft parts technological allowances. The allowance for the parts could be excluded fully or partly, or not removed at all. This value might be used for discrepancies analysis parts and assembly units, and as criteria for the technological production upgrade;
– Record keeping of non-ferrous and precious metals.
The software application for processing the aircraft levelling information affected by the mass/inertia loads on the fuselage might be a supplement for the weight control automated system.
Thus, the new model of weight control automated system will positively affect the aircraft design time, its serial production and enterprises cooperation even with partial implementation of the above-mentioned points. The weight control automated system will become a part of the life cycle informational support system article (CALS-technologies). | ||
Nabatov A. N., Vedenyapin I. E., Mukhtarov A. R. Applying ontology approach to information system design. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/bcf/Nabatov_Vedenyapin_Mukhtarov_rus.pdf The article considers the problems of corporate information systems development, design, upgrade and operation. The process complexities that are needed to be overcome by the participants – customers, the owners of corporate information systems, executors – architects, designers, programmers, implementation specialists, as well as those who will operate the information system – administrators and users, are discussed. The well-known and new approaches to the information systems design are being studied. The advantages and disadvantages of these approaches are considered. A design approach associated with the known technologies combining is proposed. At the core of the proposal is sharing the ontological and entity-relationship modeling methods. An example of the information system design beginning for an ordinary manager is considered. The example describes the environment, both technical and information, as well as classification of tasks and resources necessary for the manager while performing his official duties. The example is given based on ontological approach. On this basis the state vectors, describing the manager’s workplace, as well as his tasks, are presented. The ontologies integration into a unified structure is shown, and a conclusion on the links complication between the combined ontology elements is made. This conclusion is also confirmed by the state vector. Similarly, a connection-based approach is simulated on the same example. A principal possibility of these approaches combining based on the basic subject area commonness is shown. Generality is ensured by a single glossary, applied in both approaches. This allows conducting a comparative analysis of the obtained models. The XML representation format as the consolidation platform is proposed. It is demonstrated that both the ontology and the entity-relationship models can be represented as an XML structure. | ||
Nikolaev S. V., Barantsev S. M., Kolodezhnov V. N., Shatovkin R. R., Kupryashkin I. F. Motion dynamics modeling of objects of smooth ballistics while solving the problems of aircraft complexes flight tests. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/a36/Nikolaev_Barantsev_Kolodezhnov_SHatovkin_Kupryashkin_rus.pdf The article is dedicated to developing the mathematical model of the of aerial bombs movement smooth ballistics to determine the possibility of bombing. The mathematical model is based on the numerical solution of a system of differential equations, accounting for aerial bombs ballistic characteristics, as well as their kinematic and gravitational parameters. Ballistic characteristics determine the aerodynamic properties of air weapons, significantly affecting parameters of their trajectory, and is entered into the bombing sight while the sighting angle determining. Based on this mathematical model, a computer program meant for air weapons of smooth ballistics movement simulation after their discharge from the carrier aircraft was developed. The program is useful for scientific and methodological support of aircraft testing, flight tests planning, and movement parameters computing of the air weapons. The modeling results validity evaluation was performed by comparing he obtained results with ballistic tables. The obtained error within the limits not exceeding 5% allows recommend the developed software for assessing the combat capabilities of aircraft systems when attacking ground targets during flight tests. The obtained solutions are taken as a basis of the method for studying ballistic characteristics of air weapons and computational-experimental method for determining the combat capabilities of aircraft systems when attacking ground targets during flight tests. | ||
Lyapin A. A. Algorithm for stochastic variations generation of a vector with specified constraints. Trudy MAI, 2018, no 102, http://mai.ru//upload/iblock/115/Lyapin_rus.pdf Software for flight task analysis and control consists of a variety of interrelated components (program modules) [1]. A program module is a functionally completed software implementation of a specific task (algorithm) of a software for analysis and control of a flight task. To ensure quality and reliability, each program module should be debugged, verified and tested in autonomous mode [2, 3, 4].
The above-mentioned program modules are verified and tested using special software tools (program complex BTTesting [5, 6]).
The paper covers a method of automatic variations generation of a vector with specified constraints (imposed on the vector length and ranges of its components variation) while forming a computational grid for verification.
There are methods for constructing random vectors with dependent components [16], such as the method of conditional distributions, elimination method (von Neumann), etc. To apply the method of conditional distributions, it is necessary to determine the distribution density of the vector components, and the von Neumann method allows construct random variations of the vector components and restrictions on its length. The algorithm proposed in the article represents a simple mathematical formulation as well as easy software implementation.
An application program [17-22] integrated in the BTTesting program complex is designed based on the algorithm. The article presents user’s interface and an example of the algorithm utilization.
The presented algorithm allows to replace manual entering of initial vector parameters by their automatic generation while forming a computational grid for verification. This lowers labor efforts of a white-collar operator and prevents a human factor impact. | ||
Gerasimov K. V., Zobova A. A. Dynamics of a vehicle with omniwheels with massive rollers with account for a roller change contacting with supporting plane. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/64f/Gerasimov_Zobova_rus.pdf We study the dynamics of a vehicle with omni-wheels moving along a horizontal plane. In this work, we consider dynamics of the rollers, and suggest the model for contact switching from one roller to another using impact theory. We consider behavior of the simplified model of the omni-wheel as a rigid disk with a non-holonomic sliding constraint (MassLess Rollers Model – MLRM).
Dynamics of a symmetrical vehicle with N omni-wheels, each carrying n rollers, moving along a fixed horizontal absolutely rough plane are considered under the following assumptions: the mass of each roller is nonzero, the plane and rollers are absolutely rigid, so the contact between a supporting roller and the plane occurs in one point. The slippage is allowed only at the instant just after the change of the rollers in contact (a tangent impact).
Between the impacts, the motion dynamics are governed by the equations in pseudovelocities. Compared to MLRM, the additional terms proportional to the rollers’ axial moment of inertia and depending on the angles of wheels’ rotation appear. For free motions (without control), we showed analytically the existence of the energy first integral, cyclic linear integral for the non-supporting rollers, and slow change of the MLRM first integral. It is shown that some MLRM motions disappear. All analytical results were confirmed by simulation. Comparison of the main types of motion for symmetric three-wheeled vehicle for MLRM and the whole model was performed.
For switching between rollers, an impact theory problem is posed and solved, impact forces and energy loss being obtained in assumption of non-elastic impact and ideal constraints. Right before the impact instant only holonomic constraints are imposed on the system. After the impact, a set of differential constraints are applied. The impact problem is then formulated as a system of algebraic equations. The system admits the unique solution. We consider the impact as non-elastic in the sense that it is equivalent to projection of the vector of generalized velocities onto the plane defined by constraints in the space of virtual displacements, orthogonal in the kinetic metric. Thus, the normal part of the generalized velocities vanishes, and the kinetic energy of the system decreases by the value of the kinetic energy of lost generalized velocities, in accordance to Carnot’s theorem. Then the solutions were obtained numerically combining both smooth parts of motion and impacts. | ||
Korovaytseva E. A. On ensuring solution accuracy of model analysis problems. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/6d3/Korovaytseva_rus.pdf By the example of modal analysis problems formulation, introduction of three simplest canonical forms is suggested, allowing structuring the description of problems solution algorithms and reasonably minimize their spectrum. For the basic algorithm, supposing the method of initial parameters application, the use of integral approach to the problem solution is proposed.
This approach supposes orthogonality of normalized integral matrices of the initial and conjugate differential equation systems condition checking at each integration step at the problem preprocessing step and segmentation of integration interval at the points in which this condition is not met. This approach efficiency is illustrated by the examples of free oscillations of hinged beam and cylindrical shell problems solution analysis. It is shown, that tenth and higher natural frequencies of the hinged beam cannot be calculated correctly without using segmentation according to the approach suggested. The article compares several numerical integration methods combined with segmentation. They are Runge-Kutta method, realized in authorial program, and Runge-Kutta, Adams-Bashforth, Gear and trapezoids with free interpolation methods realized as built-in MATLAB functions. Runge-Kutta method realized in authorial program demonstrated the best accuracy and computational speed. Besides, comparison of Runge-Kutta method of the fourth and tenth orders of accuracy shows that the method of the higher order is less accurate.
Calculations of the first natural frequency and mode of cylindrical shell oscillations were performed according to the general moment theory with account for inertia in three directions. Godunov’s orthogonalization method was used. The numbers of orthogonalization and integration steps were calculated according to segmentation methodology suggested in the paper and common approximate methodology based on numerical experiments of the prior authors. The studies revealed that applying common approach to integration interval segmentation cold lead to wrong results of natural frequencies and modes calculation, while application of the approach suggested in the paper allows obtaining results with the required accuracy. | ||
Egorov A. V. Bending deflection of a non-uniform bar at axial compression. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/0b6/Egorov_rus-.pdf The article considers a process of deformation of a hinged-mounted non-uniform bar at the axial compression. Numerical computation was performed with ANSYS and LS-DYNA software, using 3D finite elements in elastoplastic domain. The fact of stability loss was being established through the values of bending deflections being determined.
The bar non-uniformity was specified by the three elastic insertions with elasticity modulus differing from basic material of the bar. The insertions were located along the bar superficies non-symmetrically relative to its axis. A steel bar with elasticity modulus of
The insertions were of a small volume: in total 0.8% relative to the bar volume.
Based on modal analysis, forms of oscillations and natural frequencies of the non-uniform bar were obtained with ANSYS software, which were compared to the shapes and frequencies of the uniform bar.
Lateral motions (bending deflections) of an axially compressed non-uniform bar were found by computing its stress and strain state with LS-DYNA software in dynamic setting, which allowed obtaining bending deflections as a function of time. For the first five forms of stability losses of the non-uniform bar corresponding loads were calculated.
Loading of the bar bending deflection over one half-wave (per the first form) was compared to Euler’s critical load. It was shown, that the obtained critical loading exceeded it by 21%. This loading can be considered as the upper estimation, since the insertions were of small volume.
With an assumption of the bar non-destructiveness, the process of shape changing, associated with large displacements was established with LS-DYNA software, and a time instant of ultimate strain reaching in the upper thin layer on the bumpy surface of the bended bar was indicated. | ||
Golubev E. S., Mugla D. R., Barzov A. A., Sysoev N. N. Probabilistic analysis of ultra-jet hydro-physical technologies effectiveness. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/436/Golubev_Mugla_Barzov_Sysoev_rus.pdf The article considers comparative effectiveness of various scientific and applied approaches to the study of ultra-jet hydro-physical technologies. The possibility of effective construction of a probabilistic simulation apparatus was demonstrated on a concrete example of determining an optimal length of a nozzle, forming the cutting abrasive-liquid jet. The results of this problem solving by simulation using Monte Carlo method, supplemented by direct experimental studies are presented. Prospects for the development of the proposed approach in the field of analysis of ultra-jet hydro-physical technologies are outlined.
The high labor-intensiveness and cost of the direct experimental analysis of the effectiveness of various operational ultra-jet technologies (UJT), as well as the search for optimal modes of their implementation in production conditions are the reasons for the need to develop the apparatus for theoretical study and mathematical modeling of the interaction of ultra-jet (UJ) and the material being processed. Besides, the task of creating appropriate engineering methods for express determination of rational conditions for ultra-jet treatment of materials and liquids, in particular, by the acoustic emission method is topical. In this regard, we formulate in short form the main options for analyzing and optimizing the physical and technological parameters of UJT designed to ensure their low-cost determination at the early stages of technological production preparation. We will herewith accoinput unt for interconnection of physically dominating UJT processes, in particular, fatigue-discrete US-erosion of the machined material or a solid-state target with input physical characteristics of various operational UJT and their output parameters. | ||
Savitskiy D. V., Aksenov A. A., Zhluktov S. V. Numerical simulation of argon plasma interaction with carbon sample of thermal-protective coating. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/a97/Savitskiy_Aksyenov_ZHluktov_rus.pdf Real picture of physico-chemical processes around a hypersonic vehicle is extremely complex. While air deceleration in the head shock wave, almost all kinetic energy of the approach flow transforms into internal energy. This leads to the air heating up to high temperature (tens of thousands degrees) right behind the shock wave, which, further, subsides, while approaching the vehicle due to endothermic reactions of dissociation and ionization. As a result, the flow of multicomponent thermochemical non-equilibrium gas mixture forms in the shock layer. Interaction of the heated gas with the thermal heat shield of the vehicle initiates numerous additional interrelated processes. They are heterogeneous chemical reactions at the vehicle surface, homogeneous chemical reactions with participation of the heat shield destruction products, conjugate heat exchange between the gas and heat shield, non-stationary coating heating. The necessity to describe these processes leads to significant complication of mathematical model. The model of the hot gas interaction with the thermal shield is defined by the coating type.
The article presents a complex mathematical model describing the hot gas mixture flow near a hypersonic vehicle, mass entrainment from the vehicle surface, the ablation products effect on the processes proceeding in the gas phase, the heat shield heating, and the vehicle surface shape changing The model is not too complex. It was developed for systematic engineering calculations of the hypersonic flows near real vehicles.
The 3D flow of argon plasma around a carbon sample of a heat shield is simulated. The conditions are corresponding to the experiment performed at the Joint Institute for High Temperatures of RAS. It is assumed, that sublimation is the main mechanism of the sample ablation. Calculations were performed with the FlowVision software. The article presents the simulation results. The numerical modeling results are compared with the experimental data. The difference between the computed and experimental values of the mass loss rate is found to be within the experimental error. | ||
Konstantinov S. G. Numerical modeling of a solid sphere free fall into the water. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/863/Konstantinov_rus.pdf A solid body motion trajectory depends significantly on its hydrodynamic characteristics. Thus, an important problem consists in determining aero-hydrodynamic forces and moments, impacting the body depending on its special position and media properties. Application of modern computing techniques, allowing accounting for complex physical pattern of the body flow-around in viscous turbulent flow of liquid and compressible gas, becomes highly relevant for determining dynamic characteristics of a solid body free falling and immersing into the water.
Computational Fluid Dynamics (CFD) methods, constructed on the solution of the Navier-Stokes equations, allow simulate the fluid and gas flows dynamics with account for the viscosity, compressibility and detachment phenomena effect.
The main problem while the CFD methods application is the simulation of turbulent flows. Until now, universal turbulence models, capable of accounting for all the scales of turbulence have not been developed. Thus, with regard to computing resources costs, the Reynolds-averaged Navier-Stokes (RANS) equations closed by a particular turbulence model are widely employed. With this approach, the numerical experiment accuracy depends largely on the correct choice of the turbulence model.
To assess the validity of the RANS method, the aerodynamic characteristics of the sphere were computed using three most widely used turbulence models, i.e. Spalart-Allmaras, k-SST and k-e, realizable in the ANSYS FLUENT program.
Comparative testing of turbulence models based on aerodynamic characteristics computing of the sphere while airflow over a wide range of Reynolds numbers revealed that the computing results obtained from the Spalart-Allmaras and k-SST turbulence models are closest to the experimental data.
To determine the aero-hydrodynamic characteristics of a sphere free falling into water, as well as the trajectory of incidence and immersion, calculations were performed using the RANS method with the k-ω SST turbulence model and Volume of fluid (VOF) and Six degrees of freedom (6DOF) models contained in the program ANSYS FLUENT.
Based on computing results, the sphere hydrodynamic characteristics, trajectory and sinking speed were determined. The patterns of the total velocity in the calculated area were obtained, and visualization of the cavity formation process in the water while immersion of the sphere with hydrophobic properties was demonstrated. The numerical modeling results of the sphere immersion into the water were compared with the experimental data.
The results of sphere aero-hydrodynamic characteristics computing and numerical modeling of the sphere immersion into the water demonstrated satisfactory agreement with experimental data, which indicates the fidelity of the physico-mathematical model of the applied method.
The implemented method can be employed in the aircraft building industry to solve problems related to determination of the dynamic characteristics of seaplanes and helicopters capable of being driven and moving along the water surface with account for the impact of the incoming airflow, currents and free surface waves. | ||
Khatuntseva O. N. On finding the critical Reynolds number of laminar-turbulent transition in Hagen-Poiseuille problem. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/dfe/KHatuntseva_rus-.pdf In the previous article [1], two solutions for the Hagen-Poiseuille problem were analytically obtained based on the Navier-Stokes equations with account for the entropy producing caused by the stochastic perturbations. The first solution corresponds to the laminar mode, and the second relates to the turbulent flow mode. The solution related to the turbulent flow mode at the central part of the tube was specified by the logarithmic velocity profile with the multiplier inversely proportional to the von Karman constant analytically determined in [1]. The solutions corresponding to the laminar and turbulent modes differ slightly directly at the tube wall. In the present work, this circumstance allows determine the minimal Reynolds number at which the transition fr om the laminar to the turbulent flow mode is feasible. The method of “discontinuous” functions was employed for these purposes.
The method of “discontinuous” functions description was offered in [2]. It may be used to describe the processes subjected to jump-like transitions, applied to the physical processes that can be uniquely described by functions in all domain of α, except the small subdomains, where these functions change their values (or values of derivatives). In such subdomains the functions may demonstrate random behavior (if tracking the argument variation many times). The task of the technique consists in searching for the relations linking the functions values and their derivatives at the subdomains boundaries with dimensions and positions of these subdomains relative to the considered domains of definition of α.
The laminar-turbulent transition completely satisfies for this model of “discontinuous” functions behavior. With small Reynolds number values only the laminar mode of a liquid flow can be realized, while with Reynolds number values exceeding certain critical value both laminar and turbulent flow modes can be realized. At that, with Reynolds number increasing the turbulent flow mode stability increases, while the laminar flow mode stability decreases. The laminar to turbulent mode transition at Reynolds numbers exceeding the critical occurs jump-like and randomly.
The critical Reynolds number found in the work is approximately 1970. | ||
Glushkov T. D., Mitrofovich V. V. The impact of a fan inlet guide vane blades design effect on its characteristics. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/57b/Glushkov_Mitrofovich_rus1.pdf During the definition of one of the modern helos’ cooling fan system’s aerodynamic perfomance, it was estimated that its aerodynamic efficiency at the operation points is much lesser then pre-calculated meaning. When analyzing velocity distribution in blade passages of pre-seriesly-built fan prototype and its high-scale model, it was determined that the reason of prototype performance reduction is insufficient flow angle at inlet guide vane (IGV) outlet. As result negative rotor airfoil cascade angle of attack α leads to insufficient energy transfer from the rotor to the airflow and reduction of fan performance.
The pre-seriesly-built prototype of fan had certain deviations from the recommended shape of the input guide vane blades, in particular, great radial tips at hub and shroud, and through slot, presented at the IGV blades peripheria, that permits to hub and shroud tip leakage flows. Downwash of flow resulted in sufficient reduction of IGV outflow angle and cutting the full pressure ψ and power λ factors. Testing of same prototype with IGV radial gaps deleted, shown that radial gaps deletion sufficiently lessens the negative impact of vane design drawbacks.
Inlet guide vane blades stagger angles θ_{IGV} significantly impacts on size, angle and direction of downwash. When θ_{IGV}<95° IGV downwash direction is contrary to rotor rotation, as result rotor inflow angle if relative movement decreases, rises airfoil cascade angle of attack and energy transfer to the airflow. If θ_{IGV}~95° IGV outflow has axial direction, and velocity distribution at rotor inlet consists to expected. When θ_{IGV}>95° IGV downwash direction coincides to rotor rotation and fan performance decreases.
It was also shown that even minor deviations from the recommended vanes coronets’ shape significantly impact upon the overall aerodynamic and cinematic features of the fan installation. | ||
Bolsunovsky A. L., Buzoverya N. P., Skomorokhov S. I., Chernyshev I. L. Computational and experimental studies of high-speed wings for advanced long-haul aircraft. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/c79/Bolsunovskiy_Buzoverya_Skomorokhov_CHernyshyev_rus.pdf The article presents the description of a design technique and results of the study of two high-speed wings of the long haul aircraft thematic models. Two values of the cruise Mach number were considered: quite mustered in the world practice M = 0.85, and near transonic one M = 0.9. The wing for M = 0.85 has a sweep of χ_{1/4 }= 32.7° and average relative thickness of t/c=11.2%, while for the more high-speed wing the sweep was increased up to χ_{1/4}=38.5°, and the relative thickness was reduced to `t/c =9.5%, which was comparable to the B-747 wing parameters.
The wings were being designed using the aerodynamic design technique developed by the authors, which employs direct and inverse methods of computational aerodynamics, as well as optimization procedures. The design is performed in three stages. At the first stage, the initial geometry of the wing is selected according to the available data from the prototypes. An the second stage, it is being modified by solving the inverse problem with a given favorable pressure distribution at the main cruise flight mode. The specified pressure distribution is selected by the designer so as to minimize the wave drag (to weaken or even eliminate the shock waves), profile drag (to weaken strong pressure gradients and eliminate flow separations) and induced drag (to provide close to the elliptical load distribution over the span). Finally, the third stage commences a multi-criterion optimization procedure intended to expand the range of flight modes with minimal drag losses.
The thematic models were tested in TSAGI’s transonic wind tunnel T-106M both at cruise speeds and at low Mach number M = 0.2. The tests confirmed that the developed wings indeed ensure the achieving of the design cruise Mach number of M = 0.85 and M = 0.9 correspondingly and may be recommended for prospective long haul aircraft layout developing. | ||
Zharenov I. A., Kulesh V. P., Kuruliuk K. A. Measuring deformation fields of panels suffering impact damages with videogrammetry method. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/134/ZHarenov_Kushesh_Kurulyuk_rus.pdf While operation the aircraft structures are subjected to mechanical, thermal, acoustic and other loadings, which lead to their forms changes, i.e. deformation. Normal functioning of such objects depends on adequate response of the structure to the external impacts. One of the most important factors affecting the strength, survivability and safety of aircraft engineering objects is the impact damage of the skin.
The processes associated with impact damage to the skin are of great interest in the studies of the aircraft of structural elements strength. The processes associated with the skin impact damage are of great interest while studying the strength of the aerial vehicle structure. To develop structures stable to the impact damages and forecasting possible changes of their functional and strength characteristics the studies based on computational methods are employed and new models are created. However, these models and techniques require experimental verification and confirmation. The impact damages peculiarity consists in significant three-dimensionality of the skin normal deformation. Thus, deformation distribution fields measuring with high point density is necessary for mathematical models correct verification. The optical method of videogrammetry (VGM) is one of the prospective methods for such measurements.
The presented article offers the application of the optical method of videogrammetry for non-contact measuring of the residuaal deformation fields of the skin while impact damages inflicting. A measuring technique employing a single digital camera was developed.
Testing of a series of panels of aircraft structures from aluminum alloy was performed. The root-mean-square error of measurements of normal deviations of points on the dents’ surface up to 7mm depth did not exceed 0.01 mm.
It was demonstrated, that the measurements with high points density by the VGM method opens possibility to determine the shape and volume of the dent, which allowed verify the finite element model of the impact damage more completely. | ||
Trofimchuk M. V., Krovjakov V. B., Berezovsky D. V., Andreev M. V. Aircraft protecting unit from mechanical impact of hitting elements. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/3b4/Trofimchuk_Krovyakov_Berezovskiy_Andreev_rus.pdf Among the aircraft indices such as tactical, flight-performance, operational, economic, etc., the most important for a military aircraft is its combat survivability as an aircraft’s capability to continue the flight and task performing in conditions of hitting its separate units, systems and airframe by enemy’s means of destruction took place.
The experience of military conflicts reveals that the combat survivability of an aircraft is primarily determined by the protection of vital aggregates, which constitute less than 20% of the total aggregate of airframe and engine systems. Thus, to minimize the weight and size costs on ensuring the combat survivability of an aircraft, it becomes sufficient to ensure locally or strengthen protection with modern effective means only of its vital aggregates.
The disadvantages of existing methods and means of local protection of vital aircraft units are as follows:
– aerodynamic characteristics deterioration when placing the armored elements outside the fuselage;
– the aircraft useable volumeы reduction when placing the armored elements inside the fuselage;
– substantial increase in the aircraft weight characteristics.
As a result of the studies performed routinely by the specialists of Air Force Academy, a technical solution was developed of the device for aircraft protecting from the mechanical impact of the hitting elements. Its essence lies in the fact that along the perimeter of the aircraft skin section from its inner side, a flexible impediment is fixed in the zone of vital units’ location, and its area herewith exceeds the area of the protected skin area. Thus, the problem of fixing a flexible obstacle in the constructive state of “slack” (sagging) is solved, by which the effect of its resistance increasing to the impact of hitting elements is achieved. In this case the number of secondary fragments impacting the aggregates decreases by 95 to 97%. The energy of the damaging element itself decreases to a value sufficient only to form dents on vital aggregates that do not lead to their failure. The probability of accomplishing a combat mission by an aircraft increases by 15-18%.
The advantage of the developed technical solution is the possibility of its installation not only on newly designed, but also on the aircraft in operation without significant mass-size costs. The developed device can also be implemented to protect the other mobile and fixed technical facilities, including ground structures. | ||
Andreev D. V. Analysis and control of technical risk levels at various lifecycle stages of helicopters. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/550/Andreev_rus.pdf The article analyzes the problem of ensuring a helicopter flight safety at its design stage. As a criterion of the degree of safety estimation the notion “risk”, being spread on the functioning of a complex technical object is used. The author suggests solving the problem of flight safety provision using the “acceptable risk concept”. Unlike the existing risk assessment model bearing exceptionally statistical character, the proposed approach provides not only risk assessment, but also risk management through the implementation of special measures. These may include, for example, a limitation on the operating conditions of the helicopter and / or additional technical procedures during its operation.
The methodological basis for risk assessment is the fail-safe tolerance analysis, which shows the ability of the system (or helicopter as a whole) to ensure the safe completion of the flight in the expected operating conditions in the event of a failure onboard. It allows determine the reliability of systems and helicopter as a whole. In case of their inconsistency to the specified requirements, the analysis of fail-safe systems allows solve the problems of optimizing the architecture of the helicopter systems as far back as at the design stage. The analysis results can also be used for planning the periodicity and preparation of works on maintenance and repair of the helicopter, or transferrring certain systems for maintenance according to “their actual state”. Such technique will allow minimize technical risks at all stages of the helicopter life cycle, i.e. from the development stage to the operation stage of the serial aircraft.
The article presents classification of the failures consequences and describes the risk assessment process using the risk matrix. On the example of designing a system for indicating the main rotor rotations, the article demonstrates the possibility of selecting the optimal design variant by the fail-safe criteria. | ||
Astapov V. Y., Khoroshko L. L., Dudkov K. V. Evaluation of additive technologies application for creating models of space missile head. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/8c9/Astapov_KHoroshko_Dudkov_rus.pdf The external outlines of a head fairing affects significantly missile aerodynamic characteristics as a whole. In case of loading, they determine the aerodynamic forces and moments affecting not only the head fairing itself but also the bays to which the fairing is being fixed. The fairing outline should ensure such a gas flow-around, at which minimum zones with vortex flow character is realized. Aerodynamic models are being employed for a head fairing blow-down. It is a complex product, which is firstly being designed, and then manufactured according to the requirements to a particular testing system. Very strict requirements on geometric similarity and surface quality are being placed on the model. Aerodynamics models manufacturing according to the conventional technology is based on machining and is rather labor consuming process. The authors suggest employing new and prospective forming methods, namely additive production, to produce an aerodynamic model, which will change radically both technology and a structure. The additive production principle consists in the fact that functional products and surfaces are being created by layer-by-layer adding of material, i.e. fusing or sputtering the powder, with adding a liquid polymer or a composite. Additive technologies may be systematized according to various criteria, such as the used material phase, radiation source, layer formation method. All modern systems of rapid prototyping operate according to the similar layer-by-layer principle of a physical model construction. Additive technologies employing allows meeting specifications to the aerodynamic model.
For the aerodynamic model growth, the 3D CAD model was being translated into machine G-codes, describing the extruder or laser motion trajectory (depending on the technology). The SLA (Stereo-lithography) was chosen as a rational option in terms of the final product quality and cost. Several models were manufactured and tested at various modes. For the pipe operating area, a drainage model in 1:100 scale was developed. The goal of the tests consisted in experimental determination of the pressure distribution along the head fairing surface, as well as external pressure in the area of the most large-size superstructures installed on the model.
Prior to the head fairing aerodynamic model manufacturing commence, tests of the samples for obtaining the physical properties of the material, being obtained in the process of formation with the layer-by-layer synthesis installation, were performed. The obtained models fully meet the requirements of geometric similarity. When loaded with external loads, the models did not deflect and did not break in the joints areas. They proved their reliability while load application. The test task was experimental determination of the pressure coefficient distribution on the surface of the head fairing and in the area of superstructures. | ||
Baturin O. V., Kolmakova D. A., Popov G. M., Matveev V. N. Obtaining an equation for computing profile losses in a blade row of axial turbine while design calculation. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/c2e/Baturin_Kolmakova_Popov_Matveev_rus.pdf The article proposes a method for reliability evaluation of losses models based on statistical analysis of deviation of experimental data from calculated. It showed that those deviations are subjected to the normal distribution law, and could be described by the value of mathematical expectation and mean-square deviation .
The values of profile losses were calculated by five well-known models for 170 various axial turbines cascades, representing the diversity of turbines employed in aircraft gas turbine engines. The findings were being compared with the experimental data. The results of comparison were subjected to statistical analysis. It was found, that the best model describing the profile losses in axial turbines was the model developed in the Central Institute of Aviation Motors (Russia). It allows calculate the profile losses deviating from the actual values of losses by 8 ± 84% with a probability of 95%.
With account for the above mentioned statistical criteria, a new equation was proposed based on the analysis of the profile losses’ nature and employing mathematical optimization techniques. This equation opens the possibility of defining the profile losses of an axial turbine more accurately than by the use of the studied models. It allows calculate the profile loss values in the axial turbine deviating from the actual values of losses by 10±61% with a probability of 95%. This new proposed equation accounts for more geometric and operational factors affecting the losses value. | ||
Abashev V. M., Kiktev S. I. Assessing the channel wall deformation impact on the gas flow structure in combustion chamber. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/296/Abashev_Kiktev-_rus.-.pdf One of the most pressing problems in the design of large multichannel combustion chambers of power plants with high-speed flow is the study of the flow process in the channel and the channel walls and flow interaction. Several experimental studies demonstrated that braking in rectangular channels of high-speed flow could vary greatly from the flow in a cylindrical pipe. The article deals with calculation and theoretical study of the flow of high-speed airflow in a rectangular channel with deformed inner wall. It assessed the changes in the nature of the flow of gas flow in a rectangular channel in the presence of deformations of these sections under the impact of thermal and force loads. In this article, the authors used the finite volume method, based on the system of Navier-Stokes differential equations. The model of the shear stress (Shear Stress Transport), which is a combination of k-ε, k-ω models was used. This combination of models allows calculate both the flow of the wall-adjacent layer, and the free flow at sufficient level away from the walls. The wide application of the SST model allowed adapt it for most flows, including the stationary problems solution at large Mach numbers. The numerical studies of the large multi channel combustion chambers with high-speed flow revealed that the deformation has a predominantly undulating shape. For this purpose, design models of cut-off wedges with a deformed surface were developed. The cut-off wedges were placed in the calculated volume, through which the heated supersonic gas flow proceeded. The design model consisted of two volumes: 1 – the volume simulating the air flow, 2 – the compartment wedge.
Conclusions on the deformed surface impact on the flow structure were made. Numerical studies revealed the presence of local zones in which shocks occurred. | ||
Khomovskii Y. N. Studying specifics of strained state of a box-shape channel of ramjet engine. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/706/KHomovskiy_rus.pdf In hypersonic ramjet engines of underslung type the structural forms of air intake units, transition parts (the so-called insulators), through which the air is supplied to the combustion chamber and combustion chambers themselves represent thin-walled channels of rectangular or circular cross-sections. The airflow duct of an American X-51 hypersonic rocket and, particularly, its insulator is a consistent combination of channels of this shape.
The thin-walled structural elements of box, oval and cylindrical shape, forming the insulator sections, are exposed mainly to the pressure drops and temperature gradients. The stress state of such elements has its own specifics, and no sufficient information on it is available in the known literature sources. It relates, in the first place, to the inner corners. A significant concentration of stresses may be supposed in these places. Instead of a real insulator, let us consider the stressed state of a boxed-shape channel on the example of its six cross-sections.
The calculations were performed separately for the cases of loading by temperature gradient, pressure drop and a joint impact of these loads. The impact of R radius (R = 1; 3; 5; 13; 21; 28,5 mm) in the inner corners of models on the stress concentration factor was considered for each model.
Analyzing the obtained results, we can draw conclusions that the stresses in the corners of the models arising from the influence of pressure are very sensitive to the inner radius (in contrast to the temperature stresses). This may indicate the feasibility of separate consideration of these factors in the calculation of stress-strain state. Separate evaluation of stress concentration factors along the x and y axes may be handy for evaluating the strength of shells made of carbon-carbon composite materials with a fiber structure. | ||
Vovk M. Y., Kulalaev V. V. Normality Criteria While Processing Experimental Studies of Gas Turbine Engines Parameters Based on Applied Mathematical Statistics' Methods. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/564/Vovk_Kulalaev_rus.pdf The article performed the generalized analysis of normality distribution criteria for experimental data processing [1-20]. A new «vector» criterion and design technique were suggested and examples of distribution normality verification were given, allowing employ the limited volume of experimental data, which was a rather significant factor while gas turbine engines (GTE) tests performing. The new technique of the distribution normality evaluation while analyzing the field of the GTE workbench tests was imposed by the fact that the vast majority of the experimental data used in engineering are subjected to the normal distribution law [1-5, 8-10]. In the applied mathematical statistics in practical regard the probability distribution characteristics are considered as a center of the statistical data grouping, the degree of dissipation and random values behavior in the vicinity of the center. The symmetry relative to the distribution center is also being analyzed. In terms of applied mathematics, analysis of distributed statistics herewith requires certain knowledge, practice and intuition while primary analysis of the set of the experimental data, where subjective factor gains a significant role. The state-of-the-art condition of the GTE tests development based on applied mathematical statistics requires introduction of reliable and powerful evaluation criteria of statistical data, which possess the property of algorithmization. It reduces to minimum the subjective approaches and determines the topicality of the scientific problem, considered in the article.
While identification of a mathematical model in global software accordint
While identifying a gas turbine engine mathematical model in the global software complexes by the experimental data of a definite engine series and performing also the regressive analysis the accomplishment of condition of the normal field distribution of the experimental data is required. Thus, to ensure the validity of the regression analysis the mandatory preliminary analytical verification of the normal distribution law with the normality criteria [8-10, 13-20] in place is required. Currently, there are 21 fitting criteria, modified for the normality distribution verification [8]. The types of the fitting criteria with the normal distribution law (normality criteria) are widely presented in the bulk work [8]. The table of the strength of various criteria of the normal distribution is presented ibid [Table № 80, p.278]. The following specifics of the known fitting criteria should be noted: the criteria work well with the sample values from 8 to 5000 and require employing special tables, requiring precalculation (ex. Shapiro-Wilk criteria, Filliben, La Breck and etc.). Practically, the wellknown criteria calculations require compilng voluminous tables for the subjective analysis, which leads to serious labor costs, and requires “...not only knowledge, practice, intuition” [8], but also considerable constraints of computer employing. The newly introduced normality distribution criterion [Kr1] may be used for the experimental points array processing and regressive statistics analysis for the rig testing of various types of gas turbines and possesses algorithmization features for computer calculations. It may be employed also for creating applied the software global complexes for automated experimental data arrays processing with sufficient shortening of time and design scope on the computer including experimental dataprocessing for actual gas turbine engine tests verification. | ||
Rebrov S. G., Golubev V. A., Lozino-Lozinskaya I. G., Pozvonkov D. M. Laser ignition of oxygen-methane fuel in a combustion chamber. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/388/Rebrov_Golubev_Lozino_Lozinskaya_Pozvonkov_rus.pdf The article presents the results of the studies on the main regularities of laser ignition of an oxygen-methane gaseous fuel in a combustion chamber. A small-sized laser was installed directly on the mixing head with radiation leading-in along the axis of the chamber. The ignition was performed by initiating a spark of optical breakdown while radiation focusing in the fuel mixture volume. Mixture formation in the combustion chamber was provided by six coaxial-jet nozzles and typical for many modern liquid-fuel rocket engines operating on fuel components oxygen-hydrogen, oxygen-methane.
The studies of laser ignition specifics were performed in two directions. The first direction was determination of laser ignition possibility depending on the parameters of the fuel mixture. With this,the effect of feeding sequence of fuel components and characteristics of the mixture (pressure and flow rate) on the laser ignition possibility and ignition character were studied. The order of the components feeding was set by the control commands of the test bench. The output nozzles with various critical sections were employed for changing the flow velocity and pressure of the mixture components in the combustion chamber. The second direction of the research was studying the effect of the location of the initiation region of a spark of optical breakdown on the ignition reliability. For this purpose, lenses providing the laser radiation focusing at various distances from the mixing head plane were employed.
Final recommendations for both combustion chamber and laser ignition system characteristics selection, ensuring reliable ignition when radiation introduction into the chamber from the mixing head along the chamber axis, were given based on the results of the performed work and the obtained regularities. | ||
Legkonogikh D. S., Golev I. M., Preobrazhensky A. P., Zelenin A. N. Application specifics of electrically driven units in an aircraft power plants. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/654/Legkonogikh_Golev_Preobrazhenskiy_Zelenin_rus.pdf The article analyzes the work on the creation of electric drive units for aircraft and propulsion systems. The trends of gas turbine engines electrification are presented, the most important of which is replacement of mechanical and hydraulic actuators of propulsion unit by electric ones. The article demonstrates that application of electrically driven units in gas-turbine engine systems has a number of advantages associated with reduction mass and size parameters reduction, reliability increase, combat survivability and other operational properties of aircraft power plants. However, the effective implementation of these measures requires solution of some problematic issues of the development of onboard electric energy sources with high specific power. The review of domestic and foreign developments of electrically driven units for existing and prospective aircraft engines is presented. One of the possible options of fault-tolerant structural scheme of the fuel system of a twin-engine aircraft power plant with electric fuel pumps is proposed. This structural scheme will allow performing partial or full restoration of the fuel system in case of operational failures occurrence, as well as in the case of combat damages. The inference was drawn that at present application of electric drive for the units of relatively low power was most expedient.
For actual mass introduction of electrically driven units to aircraft systems it is necessary to carry out further works on assessing the possibility, feasibility and effectiveness of these measures. | ||
Glushkov A. V., Ulybyshev S. Y. Application of the clock mode to the propulsion system for a spacecraft high-precision orbital maneuvering and reorientation. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/2f0/Glushkov_Ulybyshev_rus.pdf The article sets forth the possibility of a clock mode operation of the propulsion system to solve effectively the problem of the spacecraft center of mass travel, as well as controlled rotation around it. Configuration of the propulsion system consisting of two triples of nominally equal liquid rocket engines with opposite directions of the resulting thrust vector located uniformly on the circumference of a given radius is under consideration. The said design solution allows effective fuel consumption to move the center of mass in space, and in conjunction with the mode of clock operation used to control the engine, ensured the high accuracy of the pulse. While the spacecraft reorienting, this algorithm allows make reversals and guidance of the selected axis in a specified direction, minimizing herewith the total increment of the characteristic speed, which leads to a linear movement of the center of mass, as well as parrying the growth of the kinetic moment along all three central axes of the spacecraft.
The article presents the description of the algorithm for the mode of clock operation of the propulsion system, as well as the results of mathematical modeling, confirming its performance and ensuring all the stated requirements. It was shown, that the problem of guidance and retention of the spacecraft selected axis in a specified direction was realized with minimum fuel consumption, and the linear travel of the center of mass was practically nonexistent. This are necessary conditions for the effective application of liquid-propellant rocket engines for a spacecraft reorientation, and this is highly demanded in practice. | ||
Giliazov M. R., Nagulin K. Y., Gilmutdinov A. H. Dynamic characteristics of galvanometric scanner for laser surface treatment. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/1fe/Gilyazov_Nagulin_Gilmutdinov_rus.pdf A high-speed galvanometer scanner for laser technological equipment was developed. Closed-loop type of galvo was selected for the précised localization of laser beam on an object surface. For angle measurement, high-speed capacitive sensor was used. This galvo presents the conjugation of a metallic rotor and stator, consisted of permanent magnets, stator plates of a special shape, and a coil.
To enhance the resonant frequency the torsion bar was fixed to the rotor end. On its other end the mirror was fixed.
The scanner ensures a deflection angle of the laser beam within the range of ±22.5° with maximum frequency of 285 Hz. The scanner dynamic characteristics were obtained by numerical simulation. The galvo resonant frequency was evaluated with the damped oscillations analysis. As the initial conditions, the magnetic field distribution precalculated in the stationary state by the MUMPS method was taken in the simulated device. Further, the time calculation was also performed using the MUMPS method, with a time step sufficient for analysis.
After that, the control signal was optimized with the help of PID-regulation of the supplied current. The criterion of optimality was the maximum linearity of the motion of the scanner’s rotor.
The change in the magnetic flux during the oscillation process over time was studied. The time for establishing the forced oscillations amplitude of the rotor (0.02 s) was estimated. | ||
Zinoviev Y. S., Mishina O. A., Glushchenko A. A. Prospects for ground- and space-based optical telescopes development. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/472/Zinovev_Mishina_Glushchenko_rus.pdf The issues of the near and far space exploration are topical in both scientific and practical terms. On the one hand, it is the study of the Solar system (including asteroids and comets), distant Galaxies, while on the other hand, it is the problem of increasing of the number of space debris and spacecraft.
The new generation of the ground- and space-based telescopes with enhanced characteristics are required to solve these problems.
The article presents the review of the prospects of the ground- and space-based optical telescopes development both in Russia and abroad. It considers the results of the works on implementation of the ground-based telescopes implementation for space monitoring developed in the USA, currently carried out, and on creating large space telescopes with controlled composed (segmental) apertures under development in several countries led by NASA.
The performed analysis of the prospects of the ground- and space-based optical telescopes development allowed revealing the basic tendencies of modern telescope building. These include the increase in the diameter of the main mirror of the telescope both through the application of the controlled composed (segmented) apertures principle, and through the methods of aperture synthesis. Besides the permeability and angular resolution increase, application of this trend allows create long-range telescopes, which is extremely important for solving the problem of asteroid danger. Another important trend is creating photometric channels of ground-based telescopes (GEODSS, MMT– 9) with high rapidity, which allows obtaining signatures of space objects with high time resolution and solve the problem of their identification. Finally, creation of a fundamentally new MMT– 9 system allowed detect and study the fast-changing (in time and space) radiation sources of unknown localization in huge survey sectors (up to 900 square degrees). It allows respond to emergencies in space close to real one. | ||
Vasil'eva A. V., Sedov D. P. The construction principles of the radio altimeter system for measurement parameters motion of the recovery capsule. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/263/Vasileva_Sedov_rus.pdf The key factor while selecting the landing system of a modern spaceship is a single requirement, namely, the necessity of multiple use of a reentry module. A simple parachute system with landing on a firm-land is not capable to slow-down a spaceship to the necessary extent, since it is rather difficult to create the landing shock absorber which would withstand such loading and protect the ship’s hull from damaging. Besides, due to uncompensated lateral velocity and under strong wind the capsule e may fall on its side. To account for lateral velocity and cant angles of a reentry module relative to the surface it is necessary to employ the system ensuring measuring of the corresponding parameters.
The radio altimeter system is included in the reentry module of a manned spacecraft and is intended to measure the current drop altitude from 500 to 0.5 m, the current components of the velocity vector of the center of masses, current cant angles of the reentry module relative to the underlying surface.
The radio altimeter system differs from the earlier designed by implementation of the original technical solutions ensuring carrying-out of the draft proposal requirements on the range and accuracy of measured parameters, built-in self-monitoring, reliability factors, vitality and withstandability to external impact.
Radio altimeter system presents is a pulse Doppler radio altimeter of motion parameters. The authors suggest employing the multi-beam two-mirrors antennae with nine beams as an antennae system.
To ensure performing the task of landing in case of failures in the system the dual redundancy of transmitting modules is implemented. Each module functions independently and executes the flight parameters measurement. The use of information from all transmitters enhances accuracy of the parameters measurement.
The article presents all basic principles of radio altimeter system developing for measuring parameters of movement of a reentry module. It demonstrates operating algorithms of the unit and basic equations for the required parameters computing. The functional diagram of the radio altimeter system was developed and the ways of its reliability increasing were suggested. The effectiveness of the suggested algorithms was substantiated by the system operation modeling. Evaluation of the radio altimeter system accuracy characteristics demonstrating correctness of the selected methods was performed. | ||
Burenko E. A., Nesterov S. V. Active frequency-selective filters designing. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/af9/Burenko_Nesterov_rus.pdf While their studying, students of radio engineering specialties necessarily face the task of designing electric frequency-selective filters [1, 2, 3]. Due to the trend towards microminiaturization and difficulties in constructing small-sized filtering devices with inductors for radio engineering systems, linear active RC-filters are widespread [4]. The article presents the examples of filters synthesis for various purposes.
The task of the filter synthesis consists of several stages:
– approximating function selection for a specified filter characteristic;
– the filter transfer function constructing according to the approximating function (any characteristic of the filter as a four-pole can be reduced to the transfer function and vice versa);
– determining the filter structure corresponding to the obtained transfer function;
– filter design and analysis of its characteristics.
There are many ways to construct a filter with a given transfer function of the desired order. One of them consists in presenting the transfer function H(p) as a product of cofactors H1(p), H2(p),.... HN(p) of the transfer functions of the first and second orders, with each cofactor is realized by a separate link (four-pole). Further, these links are connected to each other in cascade, i.e. the output of the first link is the input of the second.
The transfer function of the polynomial low-pass filter has the form:
A first-order low-pass filter with a transfer function in the form of (2) can be implemented, if a parallel RC-circuit is used in the feedback circuit of the operational amplifier. It is quite simple to implement a second-order filter. To implement the low pass filters, highpass and bandpass filters, the second order filters schemes found wide application.
Based on the above said links, the scheme of the low-pass active RC-filter of the fifth order was developed (Fig. 1), realized with the characteristic of the Legendre polynomials (Fig. 2).
Similarly, the scheme of the active low-pass RC-filter of the sixth order is shown on Fig. 3 and its optimal monotonic response is shown on Fig. 4.
To obtain the transfer function of the high-pass filter, it is enough in to replace the p operator with 1/p in equation (1):
where K_{∞} – the gain of the upper frequencies of the filter.
The scheme of the active high-pass filter of the seventh order with amplitude-frequency response on the Legendre polynomials is implemented based of the known first- and second order links.
The scheme of the active high-pass filter of the seventh order with an optimum monotone characteristic was also realized.
By replacing variables, one can convert the amplitude-frequency responce of the low pass filter to the amplitude-frequency responce of the band pass filter. To do this, the following variables must be replaced in the transfer function (1):
where is the normalized bandwidth of a bandpass filter, defined as
where f_{–}_{x} и f_{x} are respectively the lower and upper cut-off frequencies of a passband of a bandpass filter.
Based on the first- and second the order links the schemes of bandpass filters of the fifth order with amplitude-frequency responce on polynomials of Legendre and with optimum monotone approximation of amplitude –frequency characteristic are realized.
The transfer function of the cutoff filter can be obtained fr om the transfer function of the low pass filter (1) by a frequency domain conversion:
where is the normalized bandwidth of the bandstop filter. High-order cut-off filters can be constructed by cascading the considered links, parameters of the elements and characteristics are determined by the selected approximation.
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Kuznetsov V. S., Volkov A. S., Sokovikov S. A. The study of the OFDM signals with primary amplitude-phase amplitude-pulse modulation. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/90c/Kuznetsov_Volkov_Sokovikov_rus.pdf Technology of transmission with multiple carrier frequencies in the form of multiplexing with orthogonal frequency division OFDM and methods on its basis are widely accepted as one of the most prospective access schemes for application in the communication systems under development.
A new effective method of quadrature discrete modulation with receiving in the continuous channel with additive Gauss noise, called AFM-APM (amplitude-phase modulation amplitude-pulse modulation) is proposed. Due to the quadrature modulation scheme at FM-16, 8 levels of FM amplitude and 8 levels of APM signal in quadrature, this modulation method ensures frequency efficiency in the output bandwidth of
This modulation method allows realize 10 bit/count instead of 6 bit/count with the number of levels not more than with QAM-64.
The possibility of employing the suggested modulation as a method for subcarrier OFDM-signals was considered. The OFDM effectiveness is defined by the primary modulation effectiveness. With AFM-APM OFDM the 8 bit/count is realized, preserving the peak-factor at the QAM-16 level. Previously, no modulation technique allowed achieve such results. The probability of bit error to the E_{bit}/N_{0} ratio was modeled. It was demonstrated that more energy consumption was required for the AFM-APM realization. But, since AFM-APM employs cascaded modulation technique, its application in OFDM becomes possible. It is necessary to transfer to cascaded modulation implementation, which allows realizing the high efficiency with simple complexity. Each cascade realizes a part of the volume. The first cascade is FM-16 demodulator, the second is the quadrature modulation of a 4 ´ 4 system with quantization along the co-phase axis.
To compare AFM-APM with the other modulation techniques it is necessary to compare with those techniques, which ensure the same volume of data transmitted per the specified count. Since the AFM-APM provides 8 bit/count it should be compared to QAM-256. By the the modeling results asymptotic advantage of QAM-256 is about 7dB, though its realization in OFDM is impossible.
When comparing with the channel with the same frequency effectiveness and error probability q_{bit} = 10^{-}^{7}, the Gauss channel requires 36 dB, which is 5 dB more than with AFM-APM. | ||
Gogolev A. A., Gorobinskiy M. A. Micro unmanned aerial vehicle intrinsic position determining in conditions of enclosed space. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/545/Gogolev_Gorobinskiy_rus.pdf Micro unmanned aerial vehicles (micro-UAV) of a multicopter type are capable of performing a target assignment in enclosed space (indoors) due to their relative compactness and possibility to maneuver in a limited space. Modern UAV complexes employ the receiver of satellite navigation systems (SNS) GLONASS/GPS, which signals do not penetrate the premises as the main information channel. As a result, maneuvering and target assignments performing inside the premises in autonomous mode is drastically restricted while the UAV control by the operator is hampered due to the lack of visual control of the situation around the UAV and presence of the obstacles along the route path.
According to the concept of the UAV development, the task performance should perform in automatic mode. This means that UAV should have an autonomous navigation system operating independently from GLONASS/GPS signals. For this purpose, the UAV is equipped with onboard computing means, but they have certain shortcomings. The strapdown navigation system (SNS) demonstrates large drift indices and accuracy of about 2 to 3 meters; the barometer’s accuracy is about 0.5 meters which is not enough for solving the problem of autonomous piloting; magnetometer is source of significant readings outburst in case of a large metal object presence.
This article suggests the solution of the problem of determining the micro-UAV space position bypassing GLONASS/GPS signals, but employing the SNS and visual navigation system. Data processing from SNS and magnetometer is being performed by Mahony filter at 50 Hz frequency. Due to this fact, the state vector has a high updating rate and a little time of errors accumulation. The altitude computing is performed by complexing information of the barometer and Mahony filter. For spatial position determining the visual navigation system employs code guide-marks, located in the premises, for unambiguous description of ambience specifics. The visual navigation accuracy is 5 cm. Correction of Mahony filter and visual navigation is performed by complementary filter.
The presented hardware-software complex allows determine the intrinsic position, applying the onboard computer, in real time mode with accuracy of about 10 cm, which is about 1/5 of the aerial vehicle linear size. | ||
Torres Sanchez C. G., Vorontsov V. A. Design parameters evaluation of small reentry vehicle with account for initial data uncertainty. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/515/Karlos_Vorontsov_rus.pdf The article presents the analysis of trajectory parameters of a small reentry vehicle along a ballistic trajectory with account for the most significant perturbing factors, and calculation of their impact on the spacecraft mass.
The standard engineering models were applied to compute the thermal fluxes along the descending trajectory to compute the mass of the front shield of the thermal protection system. A method based on the Pflanz-Ludke method was applied to compute the parachute system parameters.
To obtain preliminary estimates of the design parameters three approaches were provided:
The design parameters computing in extreme (worst) conditions was being performed in such a way that of each parameter deviation led to the more severe conditions.
A probabilistic approach was performed using the equivalent perturbations, also called the Dostupov method. This method is used for statistical analysis of nonlinear dynamical systems. The essence of these methods is based on the fact, that instead of random realizations of parameters, as it is done in the Monte Carlo method, nonrandom quantities, called equivalent perturbations, are pre-computed in advance. These equivalent perturbations are added to, or computed from mathematical expectations. With these parameter values, the value of the function Y is calculated. Then, the required probabilistic characteristics are formulated.
The results of the study revealed that the equivalent perturbation method application allows saving from 2% to 4% on the mass of the reentry vehicle. | ||
Eliseev E. O., Krukov D. A. The system of identical data cryptographic generation based on the Diffie-Hellman algorithm. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/cf6/Eliseev_Kryukov_rus.pdf Data encryption is a method of secured data transmission. There are two classical approaches to confidential, reversible data encryption for their transfer or secured storage. An encryption key is the basis for using each of them. The purpose of the article consists in developing and studying the operation of the system for identical information generation from a source to a destination that does not employ encryption keys, but which ensures cryptographic protection. The results of this article are the network application for a full cycle of secured data exchange by employing the operations with metadata without applying linear and nonlinear functions of data and encryption keys. This application provides peer-to-peer network communication in accordance with the state diagram. The article presents both the state diagram and the algorithm. The data generation bitrate is probed by the various algorithm settings. The article contains references for increasing the algorithm efficiency and ways of preventing active mitm-attacks. It was clarified that the system envisaged the possibility of confidential and integrity data generation, if the requirements for the metadata options were satisfied. Compared to the similar cryptosystems the proposed system demonstrates relatively low speed in the case of bulky data fragments which havs high entropy distribution bytes. It remains relatively stable throughout due to the one-way functions application realized by fundamental Diffie-Hellman algorithm, and metadata of data fragments employing. For further research of the system for identical data cryptographic generation it is useful to analyze the possibility of increasing the variability of combinations and the length of a common DH-secret, as well as searching for the optimal metadata settings for the real-time generation and system attacks resistance. | ||
Lebedkin I. F., Molotkov A. A., Tretiyakova O. N. Mathematical modelling of complex heat exchange while developing SLM laser technologies. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/118/Lebyedkin_Molotkov_Tretyakova_rus.pdf An important task of development and research in the field of additive technology is mathematical models developing. A large number of changing parameters, such as laser power, speed, the bulk layer thickness, laser spot diameter, etc.) makes the process of the machine optimal operation mode selecting time consuming and expensive. Besides, various designs of created objects require creation mode of their own. Application of mathematical modeling can significantly reduce research and production costs. In this case, we start solving a simplified problem of heating the body by a mobile heat source, which is a Gaussian beam of radiation, with account for the phase transitions in the material. Calculations are presented in two versions, using third-party software that makes the calculation by the finite element method, and using its own software that performs calculation by the explicit finite difference scheme. The obtained results were compared to the results of other studies. A qualitative matching of the results was observed. The results discrepancy is caused mainly by the assumptions made while the model developing. In the future, it is necessary to account for the medium dispersion and particles movement during the process. As revealed by the experiments, the air flows movement and of the material evaporation from the surface exert a significant impact on the result as well. Strong restrictions on the spatial and temporal steps can be tried to circumvent using implicit methods with the property of absolute stability. The mathematical model and numerical computation method upgrading continues. | ||
Kurianskii M. K., Lolaev S. G., Paschenko O. B., Romanova T. N. A method for developing an optimal plan of fuel consumption by the maneuverable aircraft. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/c88/Kuryanskiy_Lolaev_Pashchenko_Romanov_rus.pdf This article considers the problem of fuel consumption control of maneuverable aircraft which fuel configuration consists of several fuel tanks distributed throughout the fuselage. Therefore, while fuel depletion in a separate tank the aircraft center of gravity changes, which leads to a change of the pitch and roll angles. Thus, the quality of fuel consumption control is determined by such criteria as the aircraft center of gravity changing relative to longitudinal and lateral axes of rotation occur within the given range; maximum fuel mass is used; the number of switches between various fuel tanks is minimal. The goal of the article consists in developing a new method of creating an optimal order of fuel tanks utilization satisfying the specified criteria.
To solve this problem, the setting of task of multicriteria combinatorial optimization was performed and the heuristic method of its solving was suggested. Since the number of switches between the fuel tanks is a discrete integer value, the problem was formulated in a discrete space. To solve the problem, the simulation model of the fuel consumption process that allows to simulate changes of aircraft’s center of gravity for a given fuel configuration and for the order of the fuel tanks utilization was created. While this method developing, the elements of greedy algorithm, method of full enumeration and branch and bound method were used.
Based on the proposed heuristic method the software implementation was developed, which solves the problem of automation of selecting optimal plan of fuel tanks utilization for a specified fuel configuration. The program can be used as a decision making support in the process of designing the fuel configuration of maneuverable aircraft. | ||
Beltyukov S. V., Philatov V. I., Borukaeva A. O., Berdikov P. G. Multi-channel detector's analysis results application for evaluation of a rank demodulator noise immunity. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/b0d/Beltyukov_Filatov_Borukaev_Berdikov_rus.pdf Characteristics of multi-channel detectors were studied to solve the problem of the valid signal detecting on the background noise. The proposed employing a rank demodulator for ensuring high noise immunity of communication channels. The results of multi-channel detector’s analysis were used to evaluate this characteristic. The conclusion is being made on the preferential use of the rank demodulator based on the study of the dependence of an error equivalent probability per information bit from the signal/noise ratio. A scheme for its application realizing reciprocal ranks computing is proposed. The article presents design equations for the error probability, probability of a summed rank presence it the signal channel and mutual probability of noise ranks with account for envelope distribution for the case of common ranking of an array consisted of kM counts of the envelope. The dependencies of error probability per bit of information for the rank modulator are also presented. A conclusion is being made that the rank modulator with a total ranking throughout the array of samples has the best noise immunity. | ||
Dobryansky V. N., Rabinsky L. N., Radchenko V. P., Solyaev Y. O. Width evaluation of contact zone between flat-oval cooling channels and transmitting module case of active phased-array antenna. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/170/Dobryanskiy_Rabinskiy_Radchenko_Solyaev_rus.pdf The layout of modern digital active phased antenna arrays involves transceivers and digital control circuits placing on the antenna canvas in each radiator, which leads to its dense filling and, consequently, intense heating. Thus, the task of heat power removing from the antenna comes to the fore and requires the development of effective thermal control systems that meet not only the requirements for active phased antenna arrays cooling intensity, but also for reliability, maintainability, structural strength under high-cycle loading conditions, etc.
The article presents a technique for deformable thin-walled cooling channels, used in mobile radar stations thermal control systems, modeling. In the idle state, the cooling channels are placed between the receiving and transmitting modules of active phased antenna arrays with small gaps, which allows their convenient installing and maintenance. While operation, the coolant hydrostatic pressure is injected into the channels, causing the channels to deform and contact the walls of the receiving-transmitting modules, ensuring the discharge of the generated heat to the external cooling system. One of the main parameters characterizing the heat dissipation intensity is the contact zone width, realized between the channels and the walls of the receiving and transmitting modules. The article solves the problem of determining this parameter. It considers the contact between deformable channels with a flat-oval cross-section and cooled surfaces of the heated receiving-transmitting modules of active phased antenna arrays. The problem is being solved with account for hydrostatic pressure acting inside the channels, the geometry of the channel cross sections and the gaps between the modules being cooled. The solution of the contact problem for a cylindrical non-axisymmetric shell is reduced to solving the problem of a beam deformation of unit width (cross-section contour) for the case of a plane deformed state. The solution was obtained in an implicit form since the width of the contact zone was defined as the root of a sixth degree polynomial. The dependence of the contact zone width on the geometric parameters (gaps, section dimensions) and the actual pressure was studied. | ||
Nesterenko V. G., Revanth R. A. Design features and efficiency of compact air-to-air heat exchangers installed in the turbofan engine's turbine cooling system. Trudy MAI, 2018, no 101, http://mai.ru//upload/iblock/da3/Nesterenko_Revant-Reddi-A_rus.pdf The article presents the designs of the basic air-to-air heat exchanger (HE) installed in the turbofan engine bypass section and its modifications based on the computational studies results performed by the authors with ANSYS CFX software. This set of studies includes studies of HE blocks consisting of individual small-sized cylindrical or oval tubes, equal in area to cylindrical tubes, having a smooth or unsmooth inner surface, with circular projections being micro-intensifiers of heat exchange.
The purpose of the study consists in determining configuration and geometrical parameters of the HE tubes that provide a higher temperature drop of cooled air withdrawn from the high-pressure compressor in the turbofan engine, such as the AL-31f and RD 33, as well as lower pressure losses in its bypass section.
The second task was to obtain the dependences of ∆Т = f (d, l) and σ = ∆р/p for various configurations of tubes and tube bundles, with the cross-flow of cooling air.
All computations were performed with the ANSYS CFX software, which ensures the comparability of the obtained computational results. From the viewpoint of possible increase in the temperature drop of cooling air and minimum pressure losses in the bypass section of the turbofan engine, the best results were obtained from a HE with oval tubes with diagonal sizes of 6.3*4.0 mm and micro heat transfer intensifiers with protrusions on the smooth inner surface of the tube with a height of 0.30 mm, installed at intervals of 5.0 mm. These tubes are recommended for application in the HE of the turbofan engine.
The final part of the work presents a new constructive scheme of tubular HE. Its tube diameter was increased to 6.0 mm, compared to the previous HE with the tubes of d_{o} = 5.0 mm diameter. Here, in one block, one tube cools the air incoming from the intermediate stage of the high-pressure compressor, which is then employed to cool the low-pressure turbine. In the other two tubes of this HE, which diameter was also increased to d_{o} = 6.0 mm, the air drawn from the high-pressure compressor outlet is cooled and supplied to cool the high-pressure turbine rotor. This design allows reduce the mass characteristics of the HE, employed in the engines consisting of two different heat exchangers, and reduce the pressure loss in the bypass section of the turbofan engine as well. | ||
Khatuntseva O. N. On accounting for stochastic disturbances effect on Navier-Stokes equations solution in Hagen-Poiseuille problem. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/108/KHatuntseva_rus.pdf The Navier-Stokes equations (NSE) are equations of the law of conservation of momentum (or the second Newton Law) for the selected fluid volume. They describe the acceleration of this volume under the action of forces caused by a pressure gradient and external forces. Notwithstanding that the NSE numerical solutions are widely used in many scientific and practice applications, the issue of proving of the possibility (or impossibility) to describe turbulent flow modes by NSE is still open. It is associated, in particular, with the fact, that the porlems allowing analytical solution (such as Hagen-Poiseulle or Couette problem) do not have solutions corresponding to the turbulent mode of the flow.
If ask a question what aspects are not accounted for while turbulence modelling by NSE, on assumption of the first principles, it can be noted that the turbulence mode as well as other stochastic processes, possesses an important statistical feature, namely, excitation of a large number of the independent degrees of freedom (pulsations) at various scales of the system consideration. The law of conservation of momentum herewith for the selected fluid volume in the NSE form, written with no accounting for this process, is violated since not all of the resultant impact, directed at the selected volume, goes into its acceleration. A part of this impact should go into excitation of the extra internal degrees of freedom.
The stochastic system entropy is the parameter, characterizing the relation of micro and macro processes. Thus, accounting for the entropy generation in the selected liquid volume in such process is obligatory. On this basis, the Navier-Stokes equations may be rewritten by introducing the total time derivative to its left part as an extra member responsible for the velocity changing while changing the differential entropy of the selected volume.
Navier-Stokes equations modification by accounting for the extra degrees of freedom, associated with stochastic pulsations excitation in a fluid flow, allowed obtain two solutions of a problem of a fluid flow in a tube with circular cross-section (the Hagen-Poiseulle problem).
One of these solutions exists at any Reynolds numbers and corresponds to the laminar flow mode. The second one is realized only at relatively high Reynolds numbers, and corresponds to a turbulent flow. The Von Karman constant was determined analytically in the expression, describing the logarithmic velocity profile in the central part of the tube. | ||
Holostova O. V., Safonov A. I. On equilibrium positions bifurcations of Hamiltonian system in cases of double combined third order resonance. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/1d7/KHolostova_Safonov_rus.pdf Motion of a near-autonomous time-periodic two-degree-of-freedom Hamiltonian system is considered near the trivial equilibrium position, stable in the linear approximation. The system is assumed to realize simultaneously two Raman third-order resonances being strong and weak. In this case, the frequencies of small oscillations are related also by the fourth-order resonant ratio. In the complete nonlinear system, this equilibrium position is unstable. By the perturbation theory methods, normalization of the Hamiltonian of the perturbed motion is performed in the members up to the fourth order inclusively with respect to disturbance, and account for the existing resonances. On the assumption that the summand coefficients related to the fourth-order resonance are small, the approximate (model) system, dependent on the three parameters, was considered. The issue of existence and number of equilibrium positions of the model system was solved by analytical and graphics methods. The domains, where the number of equilibrium positions of the model system can vary from zero to five were identified in the space of parameters of the problem.
As an application, the problem of motion of a dynamically symmetric satellite (modeled by a rigid body) about the center of mass in the central Newtonian gravitational field on the orbit with small eccentricity was considered. The satellite motion was studied near its periodic motion, emerging from the hyperboloid precession on a circular orbit. For parameter values, corresponding to the multiple Raman third-order resonance, the coefficients of the normal forms of the model system are found. It was shown, that there are three equilibrium points in this system, two of which are unstable and the third stable in the linear approximation. | ||
Pikalov R. S., Yudintsev V. V. Bulky space debris removal means review and selection. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/239/Pikalov_YUdintsev_rus.pdf The near Earth space littering with space debris is one of the most important problems of modern astronautics. The sooner the active actions on removing the most dangerous bulky objects of space debris from the orbits start, the less risk that the situation in near Earth space would develop according Kessler catastrophic scenario.
The article presents the most known and well elaborated t thus far techniques of active near Earth space clearing from space debris. The considered techniques were separated in two groups, such as a group of passive techniques of removal from the orbit, and active techniques. Passive techniques of removal suppose application of various physical fields and media for the space debris deceleration. The active techniques implies creating an artificial impact on the space debris object on the part of a space tug. Active methods are separated by the type of the impact into contactless, implying remote force impact on the space debris object, and contact techniques with direct mechanic interaction between the tug and space debris.
Remote impact on the space debris object can be performed with a laser. Here, the material ablation effect under the action of laser radiation is employed to create a small reactive force. High-speed particles flow created by the ion thrusters of the space tug can also be used to create the force, affecting the debris. The flow of charged particles can be employed to transfer the charge to the space debris, and utilizing the electrostatic field formed around the it to push the debris away from the orbit. Non-contact methods are most safe for the space tug, but the acting forces level is low, which leads to a longer duration of the withdrawal process.
The techniques supposing direct mechanical interaction between the objects are most effective. The mechanical link is formed due to the capture of the space debris object by the tug. For capture either manipulators, or docking units, or net and harpoon can be employed. From our viewpoint, the most promising are capturing and transportation techniques with tether bond. These are most safe techniques for the tag. They allow control the impact level on the tug of the space debris object, especially if the space debris object rotates with significant angular velocity. The techniques forming rigid mechanical bond can be employed for capturing the objects, which do not possess significant kinetic moment.
Manipulators, special docking devices, nets, harpoons can be used to capture the space debris. In our opinion, the methods imply using of the tethered connection is most promising methods of active debris removal. These methods are most safe for the space tug, especially if the debris object rotates with high angular rate. | ||
Aslanov V. S., Sizov D. V. Dynamics of harpoon-assisted capturing of space debris. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/3ae/Aslanov_Sizov_rus.pdf This study focuses on the problem of space debris capturing with harpoon. In contrast to the existing works on this issue, the paper deals with the process dynamics and accounts for the space debris motion disturbances caused by the harpoon. The objective of the article consists in analyzing the behavior of the system consisting of space debris in orbit and a damper equipped harpoon while capturing process and after it. The paper proposes two mathematical models of capturing. The first model studies three stages of the process, namely perforation, damping, and the target motion after the harpoon fixing in it. The interacting force between the target and harpoon is considered as a time function, which parameters depend on the harpoon properties. The second simplified model is based on a hypothesis that the target and harpoon interaction is absolutely inelastic collision. Both models are applied to simulate of a lightweight target capturing, and the simplified model’s restrictions are demonstrated. A large space debris capturing is also being studied. Numerical simulation reveals that the large rotating object after its capturing either continues its rotation in the initial or in the opposite direction, or starts wavering. The article formulated the conditions for the body transition from rotation to wavering after being captured by the harpoon. The results of this work may be employed for the space debris removal systems developing. | ||
Kotel'nikov V. A., Kotelnikov M. V., Platonov M. A. Effusion of neutral gas in vacuum. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/238/Kotelnikov_Kotelnikov_Platonov_rus.pdf The neutral gas effusion into the vacuum space is studied by computer simulation methods. In General, this problem is six-dimensional in phase space (x,y,z,v_{x},v_{y},v_{z}) and non-stationary. As a hole, it is proposed to consider a rectangle, which one side is much larger than the other. This model shape of the hole due to the shear symmetry will allow on the one hand to significantly reduce the dimension of the problem (in this case, in the phase space, the problem depends on x, y, v_{x}, v_{y), }and on the other hand to obtain all the main features of the distribution of gas parameters in the computational domain. The computational model of the problem is based on the method of successive iterations in time, when the transition process from the initial to the final stationary state is modeled, that is, the establishment of the distribution of gas parameters in the computational domain. The methods of characteristics were used to solve Vlasov equation. The calculation algorithm was implemented in the form of a computer program in C++ using the tools of the OpenGL graphic library. The size of computational domain was of 2 x 2 and contained 39942400 cells of the computational grid, the time step was of 0.01 h_{t} dimensionless units. Control of the count end time was performed visually using a graphic window displayed on the screen during the account. According to the observations on the monitor, the following was observed:
These two conditions were fulfilled by the end of the calculation. Then the results were subjected to further analysis. The information on the parameters of the rarefied gas flowing from the effusion orifice to the vacuum is based on the distribution function f(t,x,y,v_{x},v_{y}), which was studied in detail in the course of computational experiments. It follows from the graphs, that the distribution function changes its shape in a typical way when it is shifted from the hole to the boundary of the computational domain along the axis of the jet symmetry. The graphs show also the fields of velocities and concentrations of gas particles in the computational domain. The conducted researches may be useful to developers of portable devices for the small leakages diagnostics employed in the vacuum and space industry. Computer simulation of effusion of a rarefied gas in vacuum gave a presentation on the features of the gas distribution parameters in the computational domain, both during the transition process and in the final stationary state. | ||
Brutyan M. A., Ibragimov U. G. Self-similarity parameter effect on critical characteristics of Hamel type compressible flow. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/ee9/Brutyan_Ibragimov_rus.pdf The article envisages the stationary flow of a viscous compressible gas flowing out the vertex of cone.
This flow is an analog of the famous Hamel flow between the two plane walls, inclined to each other at an angle. Unlike the classical case, axisymmetric compressible flow is considered. It is worth mentioning, that the studies on this theme were being carried out earlier by Williams (1967), Byrkin (1969) and others.
In this work the flow inside a cone is assumed radial, i.e. only one velocity component is not trivial: V^{*}=(u^{*},0,0). Moreover, all flow gas-dynamic parameters are assumed dependent from the distance to the source r^{*} by the power law, while conductivity coefficients are temperature dependent by the Frost law η^{*}, κ^{*}∼T^{*k}, so:
It appeared that self-similarity solutions existed only at the certain relation between the self-similarity parameter m and the power law index k in the form of 2mk=1.
In this case, the system of Navier–Stokes equations written in spherical coordinates is being reduced to the system of nonlinear second-order ordinary differential equations (ODE). The problem key parameters are included to these equations and boundary conditions. They are α, Re_{0}, M_{0}, T_{w}, Q. It was established that the solution was determined by specifying only two parameters, while three others were being found automatically.
The nonlinear ODE system was being solved at various values of self-similarity parameters: m = 5·(k = 1), m≅0.66 · ( k = 0.76 ) and m = 1 · (k = 0.5 ).The first combination corresponds to Maxwell’s molecules model, second relates to the well-known Frost’s empirical model (η, κ~T^{0.76} ), and the third corresponds to the Hard Spheres model.
It was established that the ODE system solution existed only at the cone semi-opening angle less than some critical value of α_{*}. With larger α, the medium continuity assumption becomes inapplicable (Kn=M_{0}/Re_{0}→1) _{ }, so the gas temperature on the cone wall appears negative , which is physically unacceptable.
Thus, the presented work performed the analysis of viscous compressible gas flow in a cone at various values of self-similarity parameter m and set corresponding critical flow characteristics. | ||
Vuong V. T., Gorelov S. L. Nonlinear phenomena in a rarefied gas in Couette problem. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/eb8/Vyong-Van-Ten_Gorelov_rus.pdf Heat and momentum transfer processes in a rarefied gas enclosed between two infinite parallel plates with different temperatures and moving relative to each other are studied. The Direct Simulation Monte Carlo (DSMC) method was applied to calculate the distribution of density, velocity, temperature, heat fluxes and viscous stress tensor over a wide range of Knudsen numbers and at different values of plates’ temperatures and velocities. The obtained results were compared with the analytical results for the free-molecular case and for a wide range of the Knudsen numbers. Calculations of the heat flux and friction stress (tangential component of the viscous stress tensor) were performed by the self-similar interpolation method. It was established, that there is a normal component (which is not presented both in the free-molecular flow and in the case of a continuous flow) in the transition region between the free-molecular flow and continuous flow in addition to the tangential component of the viscous stress tensor. This effect was explained by the fact, that the gas density and temperature distributions in the transition region flow were not uniform. Moreover, both normal and tangential components have essentially non-monotonous behavior in the considered range of the Knudsen numbers. Maximum magnitude of the normal and tangential components depends on the plates’ velocity and their temperatures ratio. In addition, the heat flux to the hot wall depends on the Knudsen number and can change its’ sign at a certain temperature drop ratio and the plates velocity. | ||
Borisov A. D., Vasiutichev A. S., Laptev I. V. On ramjet parameters selection, ensuring a cruising flight specified mode. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/d07/Borisov_Vasyutichev_Laptev_rus.pdf The main feature of ramjets is direct link between parameters inside the propulsion system and parameters of the incoming airflow, which in its turn determines the aerodynamic forces acting on the flying vehicle. Thus, the process of ramjet development is inseparable from the flying vehicle developing as a whole. The flying vehicle layout scheme selection requires considering large number of different options. While developing a new scheme, engineers are generally guided by the existing prototypes and/or analogues. Determining the flow path cross-sections of the propulsion system; fuel reserve and the way of acceleration to the ramjet starting point; control ranges and other parameters is performed while their optimization process along flight trajectories with given restrictions (above all, size and weight).
A large number of parameters determining the flying vehicle flight and the performance characteristics of its propulsion system, their significant effect on each other complicate analyzing the quality of the selected scheme The article presents an engineering technique allowing coordinating and optimizing the parameters of the propulsion system and the vehicle that provide a given cruise flight mode.
Parametric calculations were performed for a 600 mm in diameter flying vehicle. The dependence of thrust and specific impulse on relative inlet area and excess air ratio are presented.
The developed technique is being applied for preliminary determining the acceleration and cruising parameters of a ramjet. | ||
Blagodyreva O. V. The problem of a cruise missile aeroelastic vibrations based on Ritz method. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/bb1/Blagodyreva_rus.pdf The article presents the study of aeroelastic stability of the elastic cruise missile based on Ritz method employing a different number of approximating functions and comparative analysis with the similar computations, performed on the basis of the finite elements method (FEM).
A cruise missile performs a longitudinal short-periodical motion in an incompressible airflow. The missile is being modeled employing a beam scheme, including a fuselage, two wing straight consoles and deflectable controls, i.e. elevation rudders. The wing is considered as an elastic beam, working in bending with transverse shear and torsion, while the missile hull and stabilizer are assumed sheer rigid. It is assumed, that the wing consoles elastic vibrations occur in line with the flat sections hypothesis. Aerodynamic loads are being determined based on the quasi-stationary theory of plane-parallel flow of the wing cross-sections flow-around. The longitudinal compression of the missile body under the engine thrust impact is accounted for as well.
The unknown functions of the transversal fuselage axis displacements, the wing axis transverse displacements and torsion angle are presented in the form of expansions in generalized coordinates, representing the movement along the natural forms of oscillations of a free structure with fixed controls. Computation results convergence to a certain value close to the exact analytical solution, which is achieved by increasing the number of approximating functions, is demonstrated on an example. The graphs of the missile natural frequencies dependence from flight speed variation and engine thrust were plotted.
Critical velocities and stability regions of the missile flight were respectively determined for each method.
All calculations were performed in “Wolfram Mathematica 8”. | ||
Glazkov V. S., Ignatkin Y. M. ANSYS Fluent software verification while studying aerodynamic characteristics of Savonius rotor. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/a8b/Glazkov_Ignatkin_rus2.pdf The paper presents the results of calculations of the aerodynamic characteristics of the Savonius S-type rotor, performed by numerical modeling of CFD hydrodynamic processes in the ANSYS Fluent software package in the two-dimensional formulation of the problem. The calculation area extends over a distance 7D behind the rotor; 3D – in front of the rotor and has a width of 6D, where D is the diameter of the wind wheel. For the calculation area, a grid of a combined type was constructed and division into calculation zones was made. On the boundary between the rotating and static computed zones, the sliding condition of the grids was applied. To take into account the effect of disruptive phenomena on the surfaces of the aerodynamic profiles of the rotor, a prismatic grid of the boundary layer was constructed with different cell heights. The 6DOF solver is used, which makes it possible to simulate the problem of untwisting the wind wheel from the resting state to reaching the working rpm under the action of an incident flow of different speeds and to trace the change in aerodynamic characteristics during this unsteady regime. The dependences of the instantaneous values of the torque coefficient on the rotor rotation angle are obtained. The dependences of the averages of the power factor of the wind wheel for the different values of speed are obtained. Comparison of the obtained results with the experimental data at different operating conditions of the windmill showed satisfactory agreement. The results of calculations of the lateral force resulting from the rotation of the S-type wind wheel in the range of the velocities of the oncoming stream V = 6..7.5 m / s, squeezed by the manifestation of the Magnus effect, are obtained. These calculation results are necessary for further strength analysis in the case of installing a windmill on the supporting structures of slow-moving aircraft as an emergency source of energy. | ||
Lohmatkin V. V. Integral imaging performance evaluation models for Earth remote sensing spacecraft with account for reliability at the stage of electrical testing. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/bb4/Lokhmatkin_rus.pdf The object of the study is reliability and integral imaging performance.
The subject of investigation is integral imaging performance evaluation for Earth remote sensing spacecraft with account for reliability of onboard systems and characteristics of special-purpose hardware.
The objective of the study consists in developing simulation algorithms and models of onboard support systems and special-purpose hardware partial failure effect on the integral imaging performance of the observation spacecraft.
The article employs the logical-probabilistic approach to the operability analysis of complex engineering systems, simulation method, synthetic sampling and method of statistical analysis. The author suggests a model of onboard systems failures while electric testing in relation to a spacecraft reliability level, based on statistic material analysis on the check switch-on.
An algorithm and mathematical models of special-purpose hardware modifications failures integral imaging performance evaluation, based on the algorithm of the integral evaluation of imaging performance figures, were developed. The article suggests the technique for performance evaluation of reliability figures of the onboard support systems and opto-electronic target hardware. This technique is based on simulation of the target functioning of a spacecraft with account for onboard systems failures.
The results of the performed studies are employed at ground testing stages of the observation spacecraft at the integral imaging characteristics evaluation with account for onboard systems reliability characteristics. Employing the developed models and algorithms allows evaluate the integral imaging performance with account for the onboard systems reliability figures and onboard opto-electronic target hardware characteristics.
Mathematical models of special-purpose opto-electronic hardware failures, simulation algorithm of special-purpose hardware partial failure effect on the integral imaging performance of the observation spacecraft, and corresponding software were developed. The integral imaging performance dependence from a spacecraft reliability figures can be plotted employing the software. These dependencies allow perform complex evaluation of integral imaging performance in relation to the spacecraft reliability level. | ||
Ionov V. A., Lobkova L. A., Makovetsky M. B. Mathematical model of a passenger aircraft's emergency turbo-pump system drive. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/e30/Ionov_Lobkova_Makovetskiy_rus.pdf The paper tackles the problem of energy delivering to the onboard hydro system of an emergency turbo-pump station. This hydraulic energy is being fed into airflow by the air actuator. The turbo-pump station provides feeding for aircraft driving actuators before auxiliary power set is activated and main engines are started.
Output actuator should function without strike loads on reinforce mechanism of turbine, and without damage of aircraft structure. The pump station nominal functioning start needs 1 or 2 seconds, while total time period for the total hydraulic system action starts functioning in nominal mode is 6 to10 seconds.
Air hydraulic system, which provides station starting, has essential advantages compared to the previous emergency sources of hydraulic feeding.
Air hydraulic system needs no energy system power, its weight and size are smaller, and it is autonomous.
The article proposes the actuator mathematical model. The model is based on the gas state equations.
The coefficient of gas rate, pre-critical and post-critical gas flow depend on the vent gas flow geometry. Moving liquid volumes, liquid density, moving structure elements mass, spring stiffness, loading actuator level are accounted for.
The liquid consumption balance equation is used to describe the hydraulic cylinder action. Constant and variable throttles regulate fluid consumption. The liquid pressure gradient for these throttles depends on spring stiffness.
The results of modeling are presented as curves for the hydraulic cylinder plunger movement process, and liquid pressure in the hydraulic cylinder. Plunger movement velocity surge and plunger pressure surge are characteristic for initial period of actuator operation. | ||
Gueraiche D. ., Popov S. A. Improving the fuel efficiency of a transport aircraft by minimizing the weight of its non-planar lifting surface. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/df7/Gueresh_Popov_rus.pdf The article evaluates the effect of various design solutions, improving the wing lift-to-drag ratio of a medium-range transport aircraft, on its fuel efficiency. In particular, the most common on modern airliners design solution , which consists in employing a non-planar lifting surface in the form of the classical wing-winglet combination, has been studied in details. A designing calculation technique has been developed for determining the magnitude of aerodynamic loading for various non-planar wing configurations, with account for increments of the local angles of attack and sideslip. These local angles change simultaneously with the general angle of attack changes, resulting in a non-uniform growth of the aerodynamic force coefficient along the wing-winglet span. Geometrical analysis allowed the representing the local lift coefficient as a function of the general angle of attack of the aircraft. The integral of this spanwise lift distribution function along the wing-winglet span allowed calculate of the total aerodynamic loading. The obtained local lift distribution function along a non-planar lifting surface has been applied to estimate the changes in total aerodynamic loading of an aeroelastic wing, the non-planar upward flexed shape of which can be easily parametrized through a second order function.
Weight-equivalents comparison of different configurations allowed perform a quantitative analysis of the increase in the aircraft fuel efficiency, resulted from the increase of the lift-to-drag ratio, aerodynamic loading redistribution along the wing-span and corresponding changes of the wing structural weight. The internal structural layout of the wing was chosen arbitrarily, so the structural weight growth was determined as a function of the structural material density, given the hypothesis that sustaining the initial margin of safety without changing the wing structure can be achieved solely by choosing a material with a higher ultimate strength, and as a result a higher density. | ||
Kuz'michev V. S., Filinov E. P., Ostapyuk Y. A. Comparative fidelity analysis of turbofan engines masses mathematical models . Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/903/Kuzmichev_Filinov_Ostapyuk_rus.pdf The article presents comparative fidelity analysis of aviation gas turbine engines mass models accessible in open press. The authors of models are Torenbeek (Delft University of Technology, Nederland), Raymer (Conceptual Research Corporation, USA), Jenkinson (Loughborough University, UK), Svoboda (The University of Kansas, USA), Clavier (Cranfield University, UK and France), Guha (Indian Institute of Technology, India), Byerley (USAF Academy, USA) and Kuz'michev (Samara National Research University, Russia). Thermodynamic and dimensions parameters, used for analysis, of 77 modern bypass engines, differing significantly on working process parameters are presented in the article. Missing data for the above said base were obtained by the mathematical models identification method.
Mass of each of 77 engines was determined by all eight models, and the obtained results were compared to the real engine mass. The analysis results revealed that some of the considered models such as Guha’s, Byerley’s, Jenkinson’s and Clavier’s models are applicable only for high-scale engines and their inaccuracy does not exceed 12%. The listed models calculate the small-scale engines weight with significant error. Moreover, the error value increases with the engine size reduction. This trend applies to all models without exception. For example, Kuzmichev's model has a total error of 6.3%, but for engines weighing less than 1500 kg the standard deviation approaches 20%. Based on the analysis presented in the article, it can be concluded that Svoboda’s and Raymer’s models can be employed for the aircraft conceptual design. Besides, these models can be applied at conceptual design stage. Torenbeek’s and Kuzmichev’s models are more detailed and account for cycle parameters. Thus, they may be employed for engine cycle optimization at design operational conditions.
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Zavyalik I. I., Fetisov E. V., Trofimchuk M. V. Application of experiments planning theory methods for flawlessness evaluation of aircraft engine fuel system units. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/c04/Zavyalik_Fetisov_Trofimchuk_rus.pdf Theoretical and experimental studies, conducted at the present-day stage of domestic aviation development revealed that at the interaction of the aircraft fuel system elements and units with aviation fuel, complex physic-chemical processes, affecting technical state level of both separate units and the fuel system in general and as a consequence aircraft fault-free operation, were running.
In this connection, the problems of the aircraft fuel systems flawlessness improvement and development of new, more sophisticated methods of its evaluation seem relevant.
While aircraft operation a great number of random external and internal factors affect the of the fuel system units of the aircraft engine. It is impossible however to evaluate all these factors effect on functioning of the fuel system units of the aircraft engine.
To solve this problem, a complete factor experiment on the central compositional rotational-order plan of the second order has been carried out.
Application of the developed mathematical model while studying the of fuel system aggregates reliability with the expansion of the ranges of values of input parameters (external factors) and internal parameters of the system (fuel engine system aggregates) allows obtain a reliable estimate of the failure-free operation level of the fuel system aggregates. | ||
Orlov D. A., Saitova A. G. Spacecraft optimal control while forming an orbit of the Jupiter artificial satellite at the section of preliminary aerodynamic deceleration braking. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/678/Orlov_Saitova_rus.pdf The article studies the problem of a spacecraft (SC) movement control while executing preliminary aerodynamic deceleration in the atmosphere, and SC transition into transfer orbit after its outing the atmosphere, application of accelerating burn of reference speed in the apofocus of this orbit, and its transfer into the orbit of artificial satellite of Jupiter. Minimization of total power consumption on the orbits’ formation is employed as the basic criterion of optimality. Control laws for angle of attack and roll attitude on the atmospheric section of SC movement were determined through maximum principle of Pontryagin. Restrictions on maximum allowed values of temperature and overload, affecting the SC while the descend process in the atmosphere were accounted for.
A technique for the optimal control of a spacecraft while moving to Jupiter with account for flight dynamics specifics was developed. Using the Pontryagin maximum principle, the laws governing the angle of attack and roll at the atmospheric portion of the space vehicle motion are defined. Limitations on the maximum permissible temperatures and overloads that act on the spacecraft during the descent in the atmosphere are taken into account.
Assessment of the possibilities, and analysis of energy efficiency of this technique of putting the SC into the orbit of artificial Jupiter satellite depending on the altitudes of conditional perihelion point was performed. It was shown that for all considered initial data range the combined outing technique led to significant energetic advantage. Energy consumption is 15-20 times less, compared to propulsive technique for outing into orbits with aphelion point altitudes less than 6000 km for SCs with lift-to-drag ratio of 0.6.
The obtained results are of practical importance and may be used for the study of planets and their satellites, for the deep space in ballistic centers, scientific centers, and organizations, preoccupied with this issue. | ||
Agishev A. R. Longitude and period mean-square deviation computing after series of corrections completion near geostationary orbit. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/04c/Agishev_rus.pdf Putting a spacecraft into assigned longitude of geostationary orbit state and transfer to a new longitude state is performed on pre-calculated plans, containing information on values and time of fulfilling all orbit corrections. The result of these maneuvering contains random errors caused by measuring errors of the orbit parameters and errors of correction performing. Check measurements and extra corrections, which should be foreseen in advance, are necessary to ensure the required maneuver performing accuracy. In this case, calculation of static characteristics of random deviations, occurring as a result of performed planned corrections, is effective.
The initial data for the calculation are the plan of transversal and binormal corrections, as well as mean-square deviation of the period measuring error and mean-square deviation of correction performing error.
In the calculation, all mistakes are considered as independent random variables with a zero expectation. The main feature of method is account for the effect of each mistake on the longitude deviation. The total deviation of orbit period and longitude of the geostationary spacecraft are the period measuring error effect, as well as transversal corrections’ performing error and transversal components of binormal corrections. While calculation, all errors are assumed as independent random values with mathematical expectation equal to zero. The main peculiarity of the computation method is an accounting for longitude evolution, which is the consequence of each error, occurring while maneuvering process.
Verification of the calculation correctness was performed by the software simulation of the correcting flight of the spacecraft in geostationary orbit. Characteristic quantities of measuring and corrections performing errors were accounted for. Simulation results confirm the calculations correctness. Computed mean-square deviations correspond to its confidence interval with 0.99 probability, found from a sample of 50 realizations. Mean-square longitude deviation for a spacecraft correction was 0.9%.
The proposed method of calculation can be applied in control measurements planning and final corrections to ensure accuracy of the spacecraft transfer into geostationary orbit. | ||
Zwe M. M. Experimental determination of the variation of feed force values during drilling of printed circuit boards. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/5e2/Zve_Maung_Maung_rus.pdf The article defines the experimental dependence of the drilling force on the number of drilled holes when drilling mounting and adapter holes in printed circuit boards. Expressions for the calculation of the temperature in the cutting zone and statistical characteristics of the envelope family of the maximum values of the drill vertex temperature are given. Dispersion of the instantaneous temperature distribution of the drill tip is revealed. The number of mounting and adapter holes in one Board can be up to several thousand pieces. The defects appeared in the surface of the holes for drilling printed circuit boards. Occurrence of these defects is connected first of all with heating of a drill during drilling. At the same time, the drilling accuracy significantly affects the quality of the printed circuit Board, which, in turn, depends on the quality of the layer combination and on the material parameters. It should be noted that defects formed at the stage of drilling, not only can lead to failures, but also increase the cost of products by increasing the cost of subsequent stages, as require the introduction of additional operations in the manufacture of printed circuit boards. The reliability of the drilling process depends on: the material of the dielectric base and foil; tools, mainly drills; machine tools; drilling modes; human factor. Problems of providing process of drilling of mounting holes in printed circuit boards are caused by considerable differences in hardness of components of base materials. The main tool for obtaining mounting holes in printed circuit boards are carbide drills. They are made of tungsten carbide with cobalt carbide additives (VK6, VK8 according to GOST 3882). Drilling modes have the greatest impact on the reliability of the drilling process, since, on the one hand, they can vary in a sufficiently large range of values, and on the other hand, they provide the technologist with sufficient freedom in choosing these values. During drilling, the heating occurs during the hole drilling due to the friction force on the back surface of the drill. The cooling of the drill bit provides pupils with the transition of the tool from hole to hole. Educated family of functions allows to statistically assess the variation of the technological characteristics of drills within a single batch and, consequently, to predict the durability of the drills and, consequently, the probability of failure of the process of drilling holes. At each moment of time, the dispersion of the maximum temperature values in the heating-cooling cycle will be subject, based on the conditions of operation, to the normal distribution law. The experiment showed the degree of dispersion of the feed force values when drilling holes in printed circuit boards. Experimentally, the determination of the change of drilling force from the number of tested holes makes it possible to calculate the variation of the force directed normal to the rear surface. This force significantly affects the temperature in the cutting zone during drilling of printed circuit boards. | ||
Borodin V. V., Petrakov A. M., Shevtsov V. A. Simulation model for adaptive sensor networks studies. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/74a/Borodin_Petrakov_SHevtsov_rus.pdf The article presents a simulation model for the adaptive sensor communication networks effectiveness study and analysis. It presents the model structure, and describes its functional capabilities and limitations. With the aim of reducing the simulation time, a number of controlling mechanisms was implemented in the model, particularly a threshold value control of the selected set of parameters, forecasting the parameters changes, with account for previously obtained results. The proposed model is used in the following studies:
– Determining the conditions of the network staying in a steady state, and its the transition to the lock state. It was shown, in particular, that the network state estimation can be performed based the analysis of the local parameters behavior (i.e. computed at each node);
– Development and optimization of multi-station access algorithms, determining the area of effective application for adaptive network management;
– Bandwidth optimization service channel to manage the network functioning process, preventing its transition to the unstable state and the lock state;
– Analysis of the input message flow view impact on the network efficiency; size optimization of the packets allocated from messages;
– Development of algorithms for optimal network management, both local and global (network-wide) parameters;
– Development and optimization of algorithms for the service channel operation for the route information transmission;
– Development and research of routing algorithms preventing duplicate packets and looping routes, as well as determining the delivery time of routing information, network load, and the amount of transmitted information;
– Studying the network behavior in the space of complex geometry (in particular, on the surface of the hemisphere, torus, etc.), as well as in the presence of opaque partitions spatially separating the network nodes;
– Studying of the network behavior and routing algorithms in non-stationary conditions, including nodes or communication channels failures, the time variation of the selected nodes activity, changing the space configuration of the, in which the network operates.
At present, according to the results of the study, a voluminouse statistical material was obtained. A part of the results of the study are reflected in references [17–20]. | ||
Generalov A. G., Gadzhiev E. V. Developing Miniature Antenna System for Small and Microsatellites. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/c90/Generalov_Gadzhiev_rus.pdf Nowadays, active process of entire space hardware including the onboard hardware miniaturization is gaining momentum. The onboard antenna-feeder devices are also affected by this process of miniaturization. With account for a number of specifics of the onboard antennae , a relevant up-to-date problem on developing small-sized, flush-mounted, reliable, simple and high-tech antennae system for small spacecraft arises. A particularly urgent need for the onboard compact VHF antennae is felt. The article reveals the advantages of microstrip antennas application, developed on printed technology, to solve the problem of developing small-sized flush-mounted onboard antennae systems for small spacecraft.
antennae design and the material applied as a dielectric substrate are proposed and presented. Such an approach allowed reducing the onboard antenna size by 2-2.5 times compared to the existing analogs.
The article presents the design of onboard antennas for two types of small spacecraft CubeSat and “Ionospere”.
The electrodynamic modeling was performed employing CAD means. The results of developing the onboard UHF-band microstrip antenna model by finite elements method are presented. Basic model parameters such as voltage standing-wave ratio, radiation pattern, and gain were obtained and evaluated.
Further, the designed antenna layout is presented. Measurements performed employing the method of the reference antenna in the JSC “NIIEM”. The article presents the results of measuring tanding-wave ratio, radiation pattern and gain. The good agreement of the results obtained while simulation and prototyping was obtained.
Thus, a small-sized, low-profile on-board microstrip antennas for small spacecrafts were proposed and developed in this article. | ||
Gorbulin V. I., Khodor M. A. Distribution technique of observation facilities fields of vision in the area of responsibility. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/7f4/Gorbulin_KHodor_rus.pdf The article substantiates the proposal multi-channel panoramic optoelectronic means application for the air situation monitoring. The task on the fields of view distribution of the surveillance facilities in the area of responsibility was set. The article describes the specifics of algorithms building for the field of observation of a panoramic optical-electronic devices, depending on the form of fundamental of the of accommodation centers lattice of the fields of view of elements of the monitoring tools.
The described technique allows determine the best of all considered structure of photosensitive elements’ fields of view allocation and dimensions required for it at specified number of photosensitive elements and the size of area of responsibility. Analysis of computation results performed for various correlations of zone of responsibility size of fields of vision of observation facilities and different photosensitive elements number revealed the absence of the best lattice options. Hence, there is a need to automate the development of the best version of the lattice and calculate the parameters of the Dirichle region. This conclusion indicates the relevance of the presented algorithm.
Visual analysis of the options graphical representation of for covering the panoramic optical-electronic means area of responsibility suggests a certain redundancy of the panoramic optical-electronic means’ area of vision, which leads to the diversion of resources to control the space outside the designated area and, also to a decrease in efficiency as a result. With account for the potential range of he considered air objects detection and the their speeds range, efficiency is one of the critically important parameters, and in conditions of military operations it requires elimination or maximum possible reduction of all negative factors.
To eliminate the indicated disadvantage, the article proposed to optimize the coating by the fundamental parallelogram deformation. The comparison of the values of the coating coefficients obtained by two methods reveals the advantage of the technique, using deformation among the overriding options of the lattice of 12%. | ||
Bulygin M. L. Realization specifics of multi-beam exposure modes with beams frequency separation in spaceborn synthetic aperture radar based on active phased-array antenna. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/95b/Bulygin_rus.pdf Multi-beam SAR modes allow increase imaging parameters (such as swath, resolution) in AESA-based spaceborne SAR systems. An example is a multi-beam SAR mode with azimuth DBF with frequency separation of beams at the receiver.
However, multi-frequency echo-signal receiving by analog AESA is leads to frequency dispersion of AESA on receiving. This effect leads to additional deviation of each beam in elevation and additional amplitude losses. As a result, it leads to deterioration in multi-beam SAR modes performance: the swath shortens, and energy performance decreases.
AESA frequency dispersion effect while receiving can be slightly reduced in multi-beam spotlight mode, where this effect reduces swath. It can be achieved by antenna pattern extension in elevation.
AESA frequency dispersion on receiving leads to omissions in milti-beam ScanSAR imaging, which is unacceptable. In milti-beam ScanSAR this effect’s compensation is possible in two ways.
The first one is special alternation of current frequency values between the beams. This option does not increase the azimuth sector to which the beams are directed. But it can be applied in multi-beam ScanSAR only when the beams number is equal to the number of partial strips of scanning.
The second one is implemented by operative control of multi-beam pattern azimuth position. The multi-beam pattern is being redirected in azimuth through switching to the next partial strip. This option increases more than twice the azimuth sector in which the beams are directed. But it can be used at an arbitrary number of beams and partial strips of scanning.
Increasing the number of partial scanning strips weakens the AESA frequency dispersion effect on the swath on receiving in multi-beam modes, since it affects only the first and the last partial strips.
In this way suggested ways of compensating the effect of AESA frequency dispersion on receive allows reduce the effect of this impact on imaging characteristics. Moreover, an algorithm of inter-beam current frequency values alternation uses less azimuth sector in which beams are directed than an algorithm of operative control of multi-beam pattern azimuth position. It may be important in spaceborne SAR systems where AESA beam deviation in azimuth capability is limited. | ||
Uryupin I. P. Synthesis of piecewise-smooth approximations of aircraft movement trajectories. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/03b/Uryupin_rus-.pdf The goal of the study consists in developing an algorithm for optimal switched systems synthesis. Switched systems relate to hybrid control systems and described by differential equations and recursion inclusions. They serve as mathematical models of dynamic systems with an automata part. Switched systems find wide application in aerospace engineering in the field of flying vehicles movement control. The article envisages the problem of optimal trajectory synthesis of the switched system, approximating a continuous trajectory of the aircraft movement. The trajectory is a
The trajectory is a piecewise-linear function and, in general, it cannot coincide with the predetermined continuous curve. Solution of the set problem allows develop and check a method of synthesis of optimal piecewise smooth approximations of movement trajectories which can be employed in complex applied problems.
The algorithm is based on sufficient conditions of optimality. The synthesis technique consists in finding generating functions of price, conditional optimal structures and conditional optimal switching moments from which the price function is compiled (the Hamiltonian – Jacobi – Bellman function). The synthesized optimal positional structure of the switched system allows receiving optimal trajectories for any initial states.
The result of this work is the solution of the problem of synthesizing optimal piecewise smooth approximations of the aircraft movement trajectories, as well as the method applied herewith of creating generating functions of the price and an optimal positional structure. The developed method may be impemented in Aerospace area.
The problem solved in the article can be employed as a test task for theoretical research in the field of optimal control. The developed algorithm of creating generating function of the price and a positional structure for the trajectories piecewise smooth approximations can be applied to solve other more complex problems. Given, that even in academic examples the solution is numerical, the application of the proposed synthesis methods is inextricably linked with the development of appropriate approximate algorithms, as well as programs for the numerical implementation of these algorithms. | ||
Semakov S. L., Semakov I. S. The simplest forecast model of time series and its reaction on linear and parabolic input impacts. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/ed1/Semakov_Semakov_rus.pdf | ||
Eremin A. I., Selvesyuk N. I. Amended estimate of landing danger coefficient while descent along glideslope with account for vertical wind. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/454/Eremin_Selvesyuk_rus2.pdf The article envisages an approach to aircraft flight-safety checkout system developing at the crucial flight stages with account for external factors and piloting errors. The kernel of the safety checkout system algorithmic provision is analytical calculation of integral danger coefficient.
Most of the accidents with human casualties occur while discent and landing. In this connection, auxiliary means for flight-safety automated control should present onboard an aircraft.
The problem of continuous aircraft landing safety control in longitudinal channel after beginning the descent along the glideslope under vertical wind action and piloting error was formulated and solved.
The specific feature of the approach proposed in the article consists in forecasting the potential consequences due to the dangerous deviations from the glide path at the hypothesis on optimal threat elimination by specified integral criterion evaluating the landing quality at the end of landing. Bellman’s dynamic programming method was employed to compute this criterion.
Scaling factors of the formula for integral danger coefficient computation were determined by computer modeling for various initial data with account of the initial piloting errors while vertical wind action in the process of the aircraft descent along the glideslope.
The article demonstrated that the suggested model for qualitative danger evaluation while landing adequately imitated pilot’s anxiety increasing and its subsiding after hazardous situation elimination. | ||
Polyakov V. B., Neretin E. S., Ivanov A. S., Budkov A. S., Dyachenko S. A., Dudkin S. O. Architecture of prospective onboard equipment control complexes. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/0e5/Polyakov_Neretin_Ivanov_Budkov_Dyachenko_Dudkin_rus.pdf Avionics of a modern aircraft is developed in accordance with the integrated modular avionics (IMA) concept, based on a common computing platform and an open network architecture. With this approach, the functions of aircraft systems (for example, flight management, stall warning, etc.) are allocated to logical sections, i.e. functional software. It is located in one or several physical modules (unified in terms of design), which are set in a common housing, i.e. a crate. Based on the IMA concept, avionics was realized on a number of aircraft, such as, MC-21, Boeing 787, Airbus A380, F-35, Su-57.
Additional advantages are provided by implementing the Distributed IMA approach. In this case, it is possible to dispose the modules in separate blocks outside the crate in the places of concentration of the onboard units and sensors. This approach allows reduce the weight and size of the cable network; increase the noise immunity of the transmitted data, and system reliability in total.
Some modern aircraft employ control systems of common aircraft equipment, which allow realize computer functions of a number of aircraft systems (such as hydraulic system, system of doors, hatches and emergency gangways, parking brake system) in a single block. Data reception from sensors, and instruction issue to actuators is performed by information input-output devices, distributed all over the aircraft. Application of the aircraft equipment control system provides the time and material expenses reduction at every stage of the aircraft life cycle due to enhancing functions of the software together with the number of computing units’ reduction, i.e. system function integration in one computing unit.
The architecture of the perspective control system for onboard equipment based on the distributed IMA concept is proposed. With increased reliability this architecture can significantly reduce the material and time expenses of onboard equipment development, maintenance and modernization. Also, the architecture of the complex components, namely, onboard equipment control module and data conversion module was proposed.
This complex was designed for performing functions with the assigned FDAL (Function Development Assurance Level) “A” (the aircraft function loss is classified as catastrophic) in accordance with the ARP4754A Standard.
To achieve this goal, the development process described in RTCA DO-178, DO-254, and DO-297 was implemented. These documents set the software and hardware development process requirements for onboard equipment of civil aviation. | ||
Dolgikh A. E., Zhidkov P. M. A model of aircraft impulse laser rangefinder operating on aerodynamic objects. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/f14/Dolgikh_ZHidkov_rus.pdf The simulation model of an airborne impulse laser rangefinder was developed. The article describes three basic structural parts of the model. The model was realized in C++. The model realized the processes of laser generation, reflection from a complex object, small signal receiving and digital information processing. Later, the obtained model results were compared to a priori information on the distance between a laser and a target. Aerodynamic targets were represented by 3D polygonal models. The rangefinder photodetector is discrete in time. Computing the number of photons for each clock cycle is performed by strobing the irradiance map over the range map. The irradiance and rang maps were created by the rendering method. To account for of different polygons’ overlapping each other, the rendering was performed employing the z-buffer algorithm. The model describes the radiation noise of photodetector was using the Poisson distribution. The readout noise was described by the normal distribution.
The range measurements are being performed several times. Then the results are analyzed by the trajectory processing. In contrast to signal accumulation, this processing is stable to the laser response shift from the target in clock cycles of photodetector unit. The true and false trajectories selection is performed by the threshold value of the trajectory length. The model operation was realized on the example of three aerial vehicles, such as Boeing747, Hornet and Tomahawk. The authors demonstrated the possibility of model tests statistical analysis for determining dependencies of operation range and measuring accuracy from pulse duration and sampling frequency of photodetector unit. The extreme value of laser rangefinder range capacity was determined by the signal/noise ratio level, ensuring stable measurements. Based on the obtained results the authors suggested application of pulse duration of τ < 100 ns and sampling frequency of about 60 MHz. | ||
Badalov A. Y., Razumov D. A. Modeling technique in a life cycle of a cosmodrome large automated system of a Smart City level. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/08b/Badalov_Razumov_rus.pdf The design and development of large-scale automated systems (AS) is always associated with surmounting of a large number of uncertainties, which structuring is often performed by employing the practice of standards and modeling in the framework of Systems & Software Engineering trend. Methods of the large systems (LS) analysis suppose their decomposition in the frame of structural and/or functional paradigms, which allow consider the obtained components as objects for functional, structural and other kinds of modeling. The complexity is stipulated by the fact, that the structural realization of such systems is ambiguous, and determined by a variety of factors, such as the presence of communication channels, the level of duty services automation, the interaction of agencies, the level of financial provision etc. Thus, the design of such LSs is associated with decomposition of the General problem at the level of the life cycle paradigm in the frame of structural and functional component hierarchy, which nodes contain the dispatching services and control centers. Besides, the problems of organizational and regulatory interaction require rather flexible approach to realization at each stage of a life cycle. While a cosmodrome of a regional level automated control system (ACS) design, the necessity occurs to optimize the taken decisions. Systems of this kind are functioning at all time and continuously, irrespective of automation level. In this sense, the time of their operation possesses a power of the continuum. Thus, the presented article suggests modeling technique exactly within the life cycle (LC) of a cosmodrome LS, including implementation of a simulation model for the system key performance indicators (KPI) optimization. The presented materials come in handy for the designers of large regional automated systems in the Smart City context such as cosmodrome ACS, as well as ASs of regional and municipal levels, ASs of a large-scale sporting events of national and international levels, situational centers of regional and municipal governments, departmental automated systems, including such a specific sphere, to which organs of government and management are related. | ||
Sokolov S. V. The Integrable Case of Kovalevskaya in a Non-Euclidean Spase: separation of variables. Trudy MAI, 2018, no 100, http://mai.ru//upload/iblock/7ef/Sokolov_rus.pdf In this paper we consider the problem of the motion of a Kovalevskaya top in non-Euclidean space. Applying, as in the Euclidean case considered in the classical papers of Kovalevskaya and Ketter, non-trivial transformations of phase variables involving both generalized coordinates and conjugate momenta, we find the Abel-Jacobi equations and give the separating variables on the plane.
As is well known (see, for example, [1]), Helmholtz proposed, in the axiomatic construction of mechanics, to abandon the Euclidean property of space, and postulate only the possibility of the motion of a rigid body typical for all Riemannian spaces of constant curvature. In the light of this it is obvious that the study of the dynamics of a rigid body in spaces of constant curvature is of prime importance.
Referring to the recent review [1] for a detailed explanation of the history of research, as well as modern statements of problems in this relevant field, we note only that in classical papers attention is concentrated on obtaining equations of motion and searching for additional integrals. In this paper, following the work of Kovalevskaya [2] and Ketter [3], we obtain separated equations for the problem of the motion of the Kovalevskaya top in non-Euclidean space. As a direction for further research, one can indicate an analysis of the stability of motions that are specific to Hamiltonian systems that are completely integrable with respect to Liouville, by methods that were developed in [4,5], as well as a classical analysis of orbital stability (see, for example, [6-18]).
As a result we are reducing an integration of the original problem to hyperelliptic quadratures. An analytical expressions which were derived in presented paper can be used for the subsequent analysis of the phase topology. | ||
Larina E. V., Tsipenko A. V. Experimental data on flow in gas ejector for turbulence model verification. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/daf/Larina_TSipenko_-rus.pdf Gas ejector is a convenient device for verifying mathematical models, which is based on comparison with experimental results. Advantages of flow in an ejector for a numerical experiment:
The authors considered a single-stage axisymmetric ejector of the classical single-nozzle design. Compressed nitrogen was employed from the balloon system with a stagnation temperature of 300 K. The article presents all necessary geometry, inlet pressure in the ejection nozzle, and the pressure sensor positions. The sensors scanning slot is 0.001 s.
Data collection system ensured the time interval of 0,001 s between the two sensor readings. The sensors error was less than 35 Pa (0.005 psi). The results of various launches were not being averaged.
One-dimensional theory comparison with the experimental data reveals that the 1D theory gives a lower (optimistic) estimation of the start-up pressure. The experiments demonstrated also that minimum level of the ejector high-frequency noise corresponds to the minimum stable pressure in the vacuum chamber.
A numerical simulation of the ejector operation for several variants of the ejecting gas pressure employing the authors’ original code based on I.Kryukov and I.Ivanov code and Godunov’s method was carried out. The vacuum chamber pressure fluctuation and the shock-train separation point displacement were obtained. A numerical experiment yields acceptable average flow parameters, but absolutely unacceptable frequency characteristics.
The presented experimental data are quite complete and suitable for turbulence model verification.
The work was supported by the RFBR grants No. 16-38-60185, No. 16-01-00444a.
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Chernakov V. V., Iksanov H. S., Myakochin A. S., Nazarenko I. P. General technique for computing the test bed variant of a space power unit in transient operation modes. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/8c0/CHernakov_Iksanov_Myakochin_Nazarenko_rus.pdf The subject of this work is the power unit of the space nuclear power plant in the test bed version. The purpose of the work was to develop a general methodology for calculating the power unit of the test bed version of a nuclear power plant for space applications in transient operation modes. An additional task was to determine the minimum set of independent variables, allowing fully characterize the operation of the power plant in non-stationary modes.
The computation technique is based on a unifying physical and mathematical model of the power unit. The physico-mathematical model is being built on a modular principle and includes the models of all the components of the power unit along the energy conversion contour. The article describes also the algorithm and the scheme for calculating the parameters of a closed gas-turbine circuit in a nonstationary formulation. The technique and algorithms are described on the example of a test bed version of a space nuclear power installation with a resistor heater as a heat source.
This technique can be used to perform calculations while the design, development and evaluation of space nuclear power units efficiency, as well as in modeling and developing control algorithms for the energy conversion loop in the modes of the source thermal power alteration. The technique can also be changed and supplemented depending on the layout and design of the particular power unit, the characteristics and specifics of its constituent parts, the type of heat exchangers, heat source, etc.
The main feature of the work is that this technique allows compute all most important parameters of the energy conversion circuit of a space nuclear power unit exactly at non-stationary operating modes. This is necessary at the start-up phase and while switching from one mode to another for development of control algorithms for the entire spacecraft. | ||
Aslanov V. S., Yudintsev V. V. Cable towing of a space debris object with a cavity filled with liquid. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/3e7/Aslanov_YUdintsev_rus.pdf Space debris active transportation employing a space tug with a tether link is one of the promising techniques of near-Earth space cleaning-up. When developing such transportation means, it is necessary to account for the specifics of space debris objects, particularly, the presence of elastic structure elements, and fuel remnants. There are two types of the space debris, namely, overaged spacecraft and orbital stages of rocket carriers. On one hand, orbital stages are simpler for transportation compared to spacecraft, since they do not contain large attached elastic elements, such as antennas or solar batteries. On the other hand, orbital stages might contain fuel remnants affecting the motion of space debris and the transportation system at large. The presented work is devoted to this phenomenon. The purpose of this work is development of a simple mathematical model of a transportation system with account for the fuel remnants onboard the space debris object of a space station type.
The article studies the effect of fuel remnants on the safety of withdrawal the space debris with fuel remnants. The authors obtained equations of motion in central gravitational field of a mechanical system, consisting of a space tug, space debris object and a tether. The space debris object is considered as solid body, containing a moving mass of liquid. The liquid fluctuating in the tank is represented as an equivalent pendulum system. Stationary solutions of the equations of movement were found, and linearized equations in the neighborhood of stable stationary solutions were constructed. The results of numerical modeling, demonstrating the closeness of analytical solutions of the linearized equations and numerical solutions of the initial equations of motion are presented.
The obtained linearized equations can be useful for determining transportation system parameters, ensuring safe withdrawal of the space debris. | ||
Ruslantsev A. N., Dumansky A. M. Deformation of carbon fiber-reinforced plastic deformation under the time-varying loads. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/46b/Ruslantsev_Dumanskiy_rus.pdf Rheological effects such as creep and relaxation may appear in the material when operating under long-time load. This can lead to a delayed fracture, so it is important to analyze the regularities of polymer composite materials deformation with account to the time factor. The presented article considers models implemented for describing rheological effects, shows their advantages and disadvantages.
The most common cases of loading can be described by the relationships of hereditary mechanics. Besides the fact that the hereditary approach is the most common form of a relationships between stresses and deformations at time varying loads, it allows identify a number of interrelated functions characterizing the material.
A model based on the matrix equations of the theory of laminated plates and relations of a hereditary type is proposed. It allows establish the dependence of deformations from time under time-varying loading.
To reveal time effects, the test for creep and relaxation of BMI-3/3692 carbon fiber-reinforced plastics samples with reinforcement scheme [±45°] and KMU-4L with reinforcement scheme [±20°] were performed. The BMI-3/3692 samples were tested for creep at time-varying loading also. The KMU-4L samples were tested for creep and relaxation. Resistive strain gages were employed to register longitudinal and transverse deformations. Nonlinearity and hysteresis are appearing on the stress-strain diagrams of the tested samples. Likewise, the diagrams of stresses and deformations are essentially dissimilar to each other, which can be explained by time-dependent factors.
Calculation for BMI-3/3692 carbon plastics with reinforcement scheme [± 45°] and KMU-4L with reinforcement scheme [± 20°] was performed employing the model proposed in the work. The Abel kernel was chosen as a creep kernel. Rabotnov kernel was used as a relaxation kernel.
Mechanical characteristics of the BMI-3/3692 carbon plastic were determined: E_{1} = 84 GPa, E_{2} = 80 GPa, ν_{12} = 0.04. G_{12} = 7.5 GPa. . The kernel parameters were determined by the least-squares method. Minimum of disparity of computed and experimental parameters was determined numerically. The following parameters values were obtained: α = –0.7, β = –0.05, k = 800.
The elastic characteristics of the of KMU-4 carbon plastic monolayer were determined: E_{1} = 150 GPa, E_{2} = 4 GPa, ν_{12} = 0.32. G_{12} = 3.3 GPa. The kernel parameters were also determined numerically: α = –0.8, β = –0.05, k = 150.
The article presents the graphs demonstrating a good correspondence between calculated and experimental data.
The proposed model can be used to calculate the stress-strain state of composite structures while long-term deformation. | ||
Azarov Y. A., Chernovolov R. A. Some specifics of modeling an aircraft aeroelasticity in transonic wind tunnel. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/00f/Azarov_CHernovolov_rus.pdf The article considers specifics of modeling the phenomena of the dynamic aeroelasticity, such as flutter and bugging, on dynamically congruent models in the wind tunnels (WT) in transonic range of Mach numbers.
The goal of the research is developing recommendations on similarity criteria selection for modeling the phenomena of aeroelasticity in the transonic mode by additive technologies.
The major stages of this work are analysis of existing structures of transonic aeroelastic models by weight, stiffness and strength characteristics, and comparative analysis of model materials’ specific stiffness and strength characteristics.
The article gives recommendations for the similarity criteria selection while design, manufacture and testing of dynamically similar models (DSM) in transonic WT. Implementation of the synthesized criterions will allow obtaining the reliable results of the experiment and successful transferring to the full-scale design.
It was shown, that the major problem is caused by the fulfillment of the mass similarity condition – the Newton’s criterion. This problem is stipulated by models’ structure overweighting. The article gives examples of overweighting effect on the flutter critical speed.
The design features of the main types of transonic DSMs force diagrams were considered. The effect of the main strain load carrying elements’ cross sections shapes of DSMs on DSM’s weight effectiveness was considered as well.
A comparative analysis of the specific stiffness and strength characteristics of homogeneous materials (metals), thermoplastics and isotropic composite materials was performed. This analysis results allowed obtain estimations of weight efficiency when used in DSM designs.
The article presents also the prospective directions for weight reduction of models of beam and plate scheme. | ||
Grishin A. A., Strugovets A. G. Evaluation of design decisions in the part of losses for current collection devices in the transmission of electrical energy from solar batteries. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/240/Grishin_Strugavets_rus.pdf This paper covers the slip ring assembly layer total resistance estimation method. This method is meant for application upon slip ring assembly design and engineering. The primary objective of this paper was to obtain the capability of slip ring layer heat dissipation simulation modelling based on the equivalent circuit.
The role of the slip ring assembly in the spacecraft electric power subsystem is considered; the basic structural elements of the assembly are described; the principles of operation of the device are explained. The major output performances of the slip ring assembly such as the voltage drop value across the layer of the slip rings and the total power dissipated on the device are defined. The process of current flow through the slip ring assembly is demonstrated. An equivalent circuit for a layer of slip ring assembly with ten contact rings is presented and reviewed in detail. The equation system for the equivalent circuit loop currents is defined. A relationship between the contact resistance and the impedance of the slip ring layer is established. Contact resistances are introduced into the system of equations. The formula of the impedance function of the layer of slip rings layer is obtained from the value of the contact resistances. The total resistance and the heat dissipation value of the slip ring layer upon nominal slip ring installation are estimated. The experimental and theoretical plots of the slip ring assembly layer impedance variation are provided for comparison. The adequacy of the assumptions taken and acceptability of the technique for practical application was validated. The analysis of contact resistance variation value versus the slip ring layer total resistance in case when the inner ring is displace versus the outer one was carried out.
The paper concludes that there is satisfactory convergence (within 4.5%) of the theoretical results with experimental data. Application of the above technique will allow predicting the slip rings heat dissipation variation during the design phase as well as to estimate their lifetime with lower costs. | ||
Ispulov A. A., Ivanov S. L. Accuracy evaluation of the filtering algorithms while tracking a maneuvering air target on angular coordinates. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/a96/Ispulov_Ivanov_rus.pdf At present, algorithms for coordinates and parameters evaluation of the air target (AT) movement on fighters are realized based on simplified filtering algorithms, particularly by α,β-filtering and α,β,γ-filtering. The main drawbacks of these algorithms are insufficiently accurate and stable tracking of maneuvering AT while low rate of information update and missing of adaptation to rapidly changing air combat (AC) conditions. Implementing of more complex models of a relative movement of a fighter and AT with refined parameters is one of the possible ways to overcome these shortcomings. The purpose of the paper is a comparative assessment of the filtration accuracy when tracking a maneuvering AT in angular coordinates using the α,β-filtering algorithms and the Kalman filter (KF) for the Zinger and Song models with refined parameters at a low rate of data update about the target. In the interests of obtaining an extrapolated evaluation and the operation of filtering algorithms, determination of the values of the maneuverability coefficient when an AT is performing the combat turn is required. The data on the AT spatial movement was obtained by semi-detailed simulation on the flight test-bench. Maneuverability coefficient determination was performed via correlation-spectral processing, by a transition from the time domain to the spectral domain – the direct Fourier transform. To achieve the purpose of the work, modeling of the filtering algorithms at a low information update rate about the target has been performed by statistical tests method. The mean square deviation of filtering errors has been used as an accuracy index. The α,β-filtering algorithm for the model of uniform rectilinear motion, the KF algorithm for the Zinger model, and the KF algorithm for the Song model have been analyzed. Analysis of the presented results allows us to draw the following conclusions:
Thus, to ensure high tracking accuracy of the maneuvering AT in angular coordinates in the AC conditions at a low information update rate in modern aviation sighting systems, it is advisable to apply filters that employ models of relative target movement of higher orders. The filtration accuracy index increase for the KF with the Song model is 40%, as compared to the α,β-filter, and 30% for the KF with the Zinger model. However, if AT maneuver changes, it will be necessary to implement the procedures for adapting the filter parameters to the maneuver type. In addition, the filtering algorithm selection should be performed either by the criterion of the estimation error minimum or by the criterion of the transients minimum time. | ||
Enkin A. A. Methodology for aircraft rational control law forming while performing maneuvers in horizontal plane. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/87a/Enkin_rus.pdf The article presents the methodology for agile aircraft rational controls forming while executing a turn in horizontal plane. The flight of an agile light airplane is selected as an object of study. While solving the problem of rational trajectories selection provisions of the direct variation method were assumed as a basis. The existing techniques, where the reference trajectory is set as dependence of phase coordinates from the physical time in the form of a polynomial, exhibit a significant drawback. This dependence of an aircraft speed from the trajectory geometry, i. e. time derivatives of coordinates, uniquely determine the speed at each point of the trajectory. A distinctive feature of the proposed methodology from the existing one is the aircraft control laws forming method. Control functions for aircraft roll and normal speed overload herewith are determined from the required accelerations for monitoring reference trajectory, specified in the form of polynomial dependence of phase coordinates from time. Tangenital overload control is formed on the assumption of specifics of maneuvering in horizontal plane. These features consist in the existence of a certain flight speed, at which maneuvering in horizontal plane is performed with maximum angular rate of turn. The degree of approaching this rate herewith is determined by the moment of the engine operation mode switching, and ensures the possibility of fuller realization of aircraft performance characteristics inherent to its structure (maneuvering characteristics).
Thus, the developed methodology ensures the accounting for maneuvering specifics in horizontal plane while forming an aircraft speed mode control, and allows eliminate the “stiff” dependence of flight speed from the trajectory geometry. It allows also determine the rational trajectory of the combat maneuvering in the horizontal plane, by which high levels of maneuverability inherent to the aircraft structure are achieved.
Application of this methodology is possible while developing the systems of intellectual support for a pilot’s decision-making, as well as aircraft automatic control systems. | ||
Evstifeev M. I., Eliseev D. P. Present-day approach to navigation instruments design. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/683/Evstifeev_Eliseev_rus.pdf Computer aided design systems have been widely used in developing of various technical systems. Concern CSRI Elektropribor has a long experience employing PTC Creo Elements, which shows an effectiveness of 3D modeling employed in innovative navigation devices. It allows both increasу labor productivity and cut devices developing time by paralleling activities while working on project. Moreover, it ensures quality improvement of the systems under development, while 3D models are working well for both finite element analysis of mechanical characteristics and rapid prototyping. Thus, 3D modeling has become a design standard for gyroscopes being the most complicated navigation instruments.
At present, a high-tech manufacturing faces such a critical task as developing innovative and competitiveness products. That is why risky and challenging solutions should be applied for navigation devices design. Correctness of these solutions could be achieved in two ways: computing and prototyping. As the first way, finite element analysis is widely used around the world as non-alternating method of predictive modeling. In recent years, with advancement of additive technology, devices prototyping and, sometimes, their manufacturing is being provided by 3D printing. Highlighted sequence of design provides a systemic approach to the developing based on up-to-date technology and allows suggest the following method of navigation devices design. 1) Developing 3D models of devices’ parts and assemblies. 2) Employing finite element analysis of devices’ mechanical characteristics. 3) Rapid prototyping by additive technology. 4) Errors’ determining and correcting.
The method differs from the others by implementation of closed process “design, modeling, manufacture”, which provides improvement of products quality and labor productivity. Moreover, this method is recommended for bachelor students teaching on design basics. It contributes essential part in developing engineer skills of students . | ||
Konysheva V. Y., Maximov N. А., Sharonov A. V. Wavelet analysis in linear dynamic systems control and diagnostic problems. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/911/Konysheva_Maksimov_SHaronov_rus.pdf The paper considers one of the possible approaches to solving the problem of linear dynamical systems control and diagnostics. Analysis of available publications [2, 4, 9] on the subject revealed that the statement of the problem of diagnostics assumes knowing of the current values of the dynamic systems state vector. However, measuring all the state vector coordinates is not always possible. Firstly, such situation may arise due to the lack of “access points”. Secondly, if the measurement results of some of the state vector coordinates contain “unacceptable” errors, which do not allow them to be used to solve problems of control and diagnostics of objects.
The proposed approach presupposes the existence of a control points shortage, but requires the observance of Kalman’s observability conditions, which allows restoring all the coordinates of the state vector. With this regard, the problem posed combines three problems: the problem of estimating the coordinates of the state vector, the problem of determining the altered parameters of the object, and the problem of determining the moments of appearance of these alterations (the moments of “discord”). Solution of the first problem is traditionally associated with the constructing the Kalman filter. To solve the second problem, the authors propose to apply the equations of parametric sensitivity. To localize the instants of the onset of such “discords”, the article proposes to apply the expansion of the parametric sensitivity functions in Fourier series with respect to the orthonormal wavelet basis.
The results of mathematical modeling of the solution of the problem of control and diagnostics of the simplest linear dynamical systems confirmed the operability of the proposed approach. | ||
Busurin V. I., Mevedev V. M., Karabitsky A. S., Groppa D. V. Algorithms of digital information analysis for optimizing checkup of control systems. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/244/Busurin_Medvedev_Karabitskiy_Groppa_rus.pdf The basis of technical support for information, measurement and control systems consists of electronic devices and systems for communicating, gathering, processing, transmission and display of information, which, in stages of development and production, are subjects to diagnosis.
For means of checkup and most of other types of control system tests, it is common to use checkout equipment (CE). The CE hardware and software are developed individually for the needs of specific tests of inertial control system. To simplify the design and improve versatility, this article offers to rethink the software design methodology for CE, allowing forming CE software automatically for control and diagnostics purposes of several similar inertial control systems. This solution will significantly reduce the time and cost of developing hardware and software parts of the CE.
Forming of the software is performed by attaching additional software modules (ASM), which are responsible for unique to a particular inertial control system (ICS) equipment or functionality, to basic software module (BSM). Designed software remains unchanged while being used for control and diagnosis of various ICS’s. BSM performs such functions as distributing software threads and their priorities, ASM launching and control. ASM are developed in conjunction with CE and have unique features. Interaction between the modules is performed by means of shared memory and communication protocols between modules. To sel ect ASM’s necessary to complete the specific test job, the software should analyze digital data, incoming fr om the control system. This data-analyzing algorithm is separated into several major steps: searching for keywords employing reference list, comparing reference lists and detection of ‘answer’ keywords. | ||
Bukhalev V. A., Boldinov V. A. Signals filtration at low-frequency interference in unmanned flying vehicles measuring-information systems . Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/476/Bukhalev_Boldinov_rus.pdf The authors consider the problem of information processing in measuring information systems of unmanned aerial vehicles’ (UAV) at low-frequency interference. As a rule, the classical approach to solution of the problem of low-frequency interference filtering proves to be unusable due to the estimates divergence. The authors propose to solve the put forward problem by employing optimal filters realizing the «interference whitening». The thus obtained mixture of valid signal with white noise The suggested algorithm of optimum filtering consists in preliminary passing-through of a measuring instrument output signal through the forming wideband filter. The thus obtained mixture of a valid signal with white noise is fed to low-frequency filter forming an optimum valid signal estimation. The structure and parameters of the synthesized filter depend on the nature of the low-frequency interference in the measurement channel. As a rule, intensity of UAV’s trajectory fluctuations can be considered as approximate constant and not depending on UAV control system type. On the contrary, dispersion of noise disturbance, may either increase, or decrease while UAV approaching an object. The nature of the organized interference depends on jammer actions. The optimum filtration algorithm has been constructed for both cases. The disadvantage of the proposed approach is the unjustified complexity of optimal algorithms implementation for solving applied problems. The main problem consists in an adequacy of the developed mathematical model (linearity, a small order of the equations, unauthenticity of basic data and other) to the real system under study. It feels particularly sharp while creating the UAV navigation and guidance algorithms with their tight restrictions on speed and memory of the onboard computer. One of the effective ways to solve this problem is to replace the differential equations for the coefficients that determine the passband of the optimal filter by their steady values, calculated by algebraic formulas obtained from differential equations. The simulation obtained results allow draw conclusions on the applicability of the proposed approach to filtration problems in the opto-electronic and radio engineering measuring information systems of UAV. In this case, the accuracy of angular coordinates estimating of the object of observation will decrease by 10–15% of the true values. | ||
Kovalsky A. A., Afonin G. I., Tereshenko S. V. Propositions on the main trends of central timing system modernization for ground-based spacecraft control automated complex . Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/02f/Kovalskiy_Afonin_Tereshchenk_rus.pdf There is a need for standard time signals and frequencies in various spheres of action. The necessity for frequency and time synchronization of technological and information processes at spacecraft (SC) ground-based automated control complex (GACC) is of special topicality. The article presents the main central timing system (CTS) modernization for SC GACC as well as specifics and perspectives of SC CTS GACC while employing data transmission channels of satellite communication system (SCS) “Primorka” and satellite radio navigational system (SRNS) GLONASS. The object of the study is SC CTS GACC. The subject of the study are methods and means of time signals distribution. The purpose of the study consists in increasing SC CTS GACC stability by implementation of data transmission channels of the SCS “Primorka” and the satellite radio navigational GLONASS system (SRNS). System analysis of methods and means of time signals propagation in SC CTS GACC, and possible synchronization error sources was performed in this work. The block diagram of SC CTS GACC creation with three-level architecture was developed. The upper level (the CTS backbone network) is between the State time references and central stations, which will meet the strict requirement on characteristics quality. The intermediate level between CTS central points and CTS peripheral stations will be connected by SCS “Pimorka”. The low level – between CTS peripheral station and a customer SC GAACC, accounting for the SC GAACC requiremetns. Realization of the proposed three-level SC CTS GACC will allow significantly increase the SC CTS GACC stability. | ||
Efimov E. N., Shevgunov T. Y., Kuznetsov Y. V. Cyclic spectrum power dencity estimation of info-communication signals. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/2b5/Efimov_SHevgunov_Kuznetsov_rus.pdf The paper introduces cyclic periodogram averaging block algorithm for the estimation of cyclic power spectral density (CPSD) using time-smoothing approach. A brief overview of the cyclostationarity phenomena and the corresponding cyclic characteristic functions are provided; a detailed theoretical description of the proposed algorithm focusing on the task of cyclic power spectral density estimation of the finite length digital infocommunication signals is presented. The structure of the CPSD function on bispectral plane for the case of finite length digital signals is described. The properties of the support region of CPSD on bispectral plane such as resolution element shape and effective width are taken into the consideration in order to avoid significant gaps alongside cyclic frequency axis.
In order to demonstrate the proposed algorithm as well as the advantages of the cyclostationary approach itself, a numerical simulation is carried out. A mixture of two amplitude-modulated signals with wide-sense stationary random processes used as their modulation sequences is chosen for the simulation. The parameters of the simulation such as effective bandwidths of the mixture components and their carrying frequencies are selected in a manner that a significant overlapping in the frequency domain is to occur. The analysis of the estimated cyclic power spectral density as a two-variable function obtained with the proposed algorithm allowed to successfully determine the number of the components in the signal mixture, their carrier frequencies, separated periodograms for each of the components and make the conclusion of the statistical independency of the underlying random processes. The results of the numerical simulation confirm the correct work of the proposed algorithm as well as demonstrate the selective properties of the cyclostationary approach.
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Tikhomirov A. V., Omel'yanchuk E. V., Semenova A. Y., Mikhailov V. Y. Prediction of radio waves propagation parameters when employing low-lying antennas in conditions of urban development. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/115/Tikhomirov_Omelyanchuk_Semenova_Mikhaylov_rus.pdf Design of ground mobile communication systems operating in urban conditions, including episodic networks, requires accounting for the effects of various factors of radio waves propagation on the received signal parameters. Depending on the types and urban building density the signal may contain include line-of-sight, reflected, diffracted and refracted components [1]. In the absence of a priori knowledge of obstacles’ type, size and shape the path loss can be estimated based on measurements. Empirical estimation should bear statistical character and based on determination of median values of path loss.
Due to the terrain and building types variety as well as the relative position of transceivers and, hence, difficulty to predict the effect of particular factors along the propagation pass on radio waves damping, a universal model for losses calculation while radio waves propagation in urban conditions does not exist. Models for predicting the signal level in ground mobile radio communications system can be employed only in cases of mobile networks with highly raised antennas of basic stations. Due to the growing popularity of the urban wireless networks (WLAN) and mobile ad hock networks, implicating a large number of mobile transponders, the purpose of this study is predicting of radio waves propagation at low-lying antennae in urban conditions by modifying the existing models on the ground of experimental data.
Based on the experimental study at the frequency of 870 MHz performed in Zelenograd, radio waves propagation losses were determined in conditions of urban building. The obtained experimental values of propagation loss were applied for linear approximation. The values of coefficients were determined and Stanford University Interim (SUI) model modification was suggested for urban media for the cases of antenna suspension height of up to 10 m. The article demonstrates that while estimating radio signal propagation in urban conditions with low-lying receiver antennae the attenuation degree equal to four can be employed. | ||
Yastrebtsova O. I. Conditions for the absence of “blinding” in microstrip antenna arrays. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/f30/YAstrebtsova_rus.pdf The paper considers one of the problems occurring in microstrip antenna arrays, namely the effect of “blindning” when the array radiation vanishes at certain scanning angles. The topicality of this problem is associated with wide implementation of antenna arrays in various Earth exploration satellite systems including synthetic aperture radars.
Fr om the published sources we know that this is due to the interaction of surface waves supported by the structure of the antenna array, in this case a dielectric layer, with dominant Floquet mode. Determining angles whereby the risk of “blinding” occurs is possible by applying the plane of phase constants, wh ere both Floquet modes and surface waves, excited in dielectric substrate of the microstrip antennae array, are depicted. The intersection of the circles corresponding to the surface waves with the circle of the radiating Floquet mode at a given scanning angle will mean the possibility of “blinding”.
This method was applied to the two dipole microstrip antenna arrays: in the first case the dielectric of the substrate was selected in such a way that only one surface wave of electric type was excited. In the second case, three surface waves were excited − two of electric type and one of magnetic.
Possible “blinding” angles were determined by performing plotting on the plane of phase constants. They were verified hereafter by modeling of an infinite antenna array, which allowed obtaining radiation element diagram. All the “blinding” angles found analytically appeared on the radiation patterns. The angle, not appeared while simulation, took place only in the second case, which corresponds to the theory, since the appearance of blind angles can depend, for example, on the method of the radiator excitation. The method applicability for the considered problem was confirmed thereby.
The conditions ensuring the absence of blinding angles at a given range of scanning angles were formulated hereafter. The restrictions are imposed herewith on both the distances between the radiating elements and parameters of the dielectric substrate. A famly of curves representing the dependence of maximum distance between radiating elements from maximum scanning angle of microstrip antenna array was plotted. It allowed determine structural parameters of antenna array by the maximum value of the scanning angle. | ||
Bakhtin A. A., Volkov A. S., Baskakov A. E. Studying specifics of MAC algorithms realization in mobile self-organizing communications networks. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/462/Bakhtin_Volkov_Baskakov_rus.pdf With account for the trends of mobile self-organizing communications networks development, the number of technologies and communication systems employing the principle of infrastructure building without the use base station will increase in subsequent years. Thus, more and more tasks, which should be solved on a data link layer of the system developed, are being revealed. A base station absence in the network topology generates the tasks of organizing the message delivery route selecting, which is especially important in mobile self-organizing communications networks. The concept of mobility itself, i. e. nodes’ permanent spatial motion imposes additional restrictions on the communication system. Thus, the problem of transmitting the service and information frames in conditions of a non-constant connection between nodes occurs. Currently, one of the most widely used algorithms for the environment accessing is the CSMA\CA algorithm. Stations and subscribers of the 802.11 network, that is, Wi-Fi networks are operating on its base. The algorithm is based on the principle of transferring the service frames of the RTS-CTS-DATA-ACK format. Using this algorithm allows solving the problems of a hidden node. The MACA algorithm lies at the heart of the implementation of CSMA\CA and is distinguished by the use of RTS-CTS-DATA service frames, without delivery confirmation. These algorithms have disadvantages, such as a large number of service frames in the communication channel and a possible non-delivery of the service frame with a changing network topology.
To solve these problems, an algorithm MMAC was developed. Application of this algorithm implies the presence of two or more communication channels by each node: separate communication channels for the transmission of service frames and for the transmission of data frames. Since this imposes additional costs on the implementation of the second channel, the algorithm has been modified. The LCM MAC algorithm employs the principle of separate transmission of service and information frames in different time slots.
A study of their efficiency was performed by simulating these algorithms in the software environment of Network Simulator 3. Analysis of simulation results revealed that the access algorithms for the MMAC and LCM MAC algorithms demonstrate the best packet delivery rate and network bandwidth compared to the MOCA and CSMA\CA algorithms (at the average by 20% and 500 bit / s, respectively). Based on the performed work, it was revealed that the actual task of research and development of a mobile self-organizing communication system, namely its data link layer, is the solution of a number of tasks:
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Isaev A. I., Skorobogatov S. V. Hydrodynamic verification and validation of numerical methods of the flow calculation in combustion chamber of a gas turbine engine. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/75d/Isaev_Skorobogatov_rus.pdf Currently, the engineering practice widely uses software packages for engineering design automation. They include the systems allowing solve complex problems of computational hydro-gas dynamics. The specificity of the employed mathematical tools imposes certain constraints in the course of operation. Thus, there is no universal mathematical model at present, which would reliably describe all turbulent flows specifics for the entire spectrum of problems. Instead, there are many semi-empirical models correlating well with the experimental data for only a certain range of problems.
The most widely used models are the models of Reynolds averaged Navier–Stokes equations. At the same time, these models have a greater number of variations, most of which found application in commercial software packages as well. Such diversity creates the problem of selection of the most appropriate model for the particular solution case. Thus, verification and validation are the intrinsic part of the turbulent flows numerical modeling.
The purpose of the article is the methodology of verification and validation of a flow computing in a combustion chamber air-gas channel of a gas turbine engine with transverse vortex system. The authors performed reviewed the most relevant turbulence models employed in software packages of computational hydro-gas dynamics. Their advantages, disadvantages and constraints associated with the empirical data are listed.
Based on the developed combustion chamber model, the full-scale model for hydrodynamic research and the finite element mesh for calculations in the software environment were created.
The article presents the results of experimental studies and the results obtained by numerical methods. They performed their comparison and analysis. Based on this data, the two models corresponding to the selected confidence interval, were separated out.
At the next stage validation of turbulence models was being performed. As a result, it allowed give qualitative estimate of flow kinetics over the entire computation region.
Verification revealed that of all the models considered, the best conformity with experiments was ensured by the SST k-w model and standard k-e model.
In consequence of validation, the authors managed to find that the SST k-w model reproduced the flow kinetics in air-gas channel of the combustion chamber with a transverse vortex system more correctly. | ||
Golovkin M. A., Efremov A. A., Makhnev M. S. Methods for estimating the rotary derivatives of forces and moments acting on the aircraft model. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/618/Golovkin_Efremov_Makhnev_rus.pdf
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Ashurkov I. S., Leshko N. A., Tsybulnik A. N. Conceptual model of a spaced system for complex ballistic targets radar observation. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/86c/Ashurkov_Leshko_TSybulnik_rus.pdf The article describes the model of spaced radar system with uncooperative radiation sources, integrated into a set of national technical means of space-rocket machinery tests monitoring. A model based on estimation of spatial and accuracy characteristics of complex ballistic targets elements allows selecting a rational variant of implementing a set of national technical means of monitoring at the finish area of foreign missile testing grounds.
In general terms, a mathematical model of a simulation-analytical type of a spaced radar system is being represented in a form of an interrelated structure and includes models of uncooperative source of illumination, complex ballistic target and receiving site integrated to a set of national technical means of control. Potential accuracy of coordinates measuring of a complex ballistic target was computed. Сriterion of optimality was selected as an arithmetic mean of range estimation CSR. The required information zone is represented in the form of a discrete set, for which maximum possible number of the receiving site allocation variants was determined. Further, applying the direct-searching method the value of the target function is determined for each variant of the set, which meets the specified limitations. Then the variant ensuring the goal function minimum is selected. Selection of the receiving site allocation rational variant allows realize potential capabilities of the spaced radar system for complex ballistic targets detection and measuring its’ coordinates in the full.
The proposed model of spaced radar system with uncooperative radiation sources integrated into a set of national technical means of monitoring space-rocket machinery tests being carried out by foreign countries allows select rational location and direction for receiving site at the finish area of foreign missile testing grounds. | ||
Rybalko A. A., Naumov A. V. A model for ensuring fault-tolerance of container virtual services at data centers. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/43b/Rybalko_Naumov_rus.pdf The following work is focused on the topic of enhancing the reliability of distributed services using container virtualization technology. An infrastructure based on container virtualization is presented and analyzed in the environment of changing workloads. Means of deployment, monitoring and lifecycle management are included in the infrastructure. The solution also includes a thorough description of networking exchange between services and service-monitoring system interchange of data in a multi-tenant environment. In modern datacenters the efficiency of resources usage is based on the number of business applications per host unit, while maintaining the isolation of applications from each other, as well as providing the stability, backup and disaster recovery, lifecycle management and network interconnections control.
The article compares the benefits of full and container virtualization, as well as analysis of service-oriented architecture on the base of container virtualization. The instruments analyzed from full virtualization perspective are VMware ESXi, KVM, Microsoft Hyper-V, Citrix XenServer, while OpenVZ and LXC/Docker technologies were reviewed from the side of container virtualization. One of the most important criteria analyzed is the scalability of the resulting solution built using the virtualization instruments presented above. Using container virtual machines, the number of objects on each host greatly grows, which is a more effective usage of resources from one hand, but poses a problem of monitoring and lifecycle management of a much larger number of objects on the other hand. The article analyses the network infrastructure and the monitoring toolset designed to handle much larger numbers of controlled objects than what is currently available on the market.
A hybrid architecture of Token Ring and Partial Mesh domains are presented as the more scalable and effective solution in the article for network communications between container hosts and between containers themselves. This hybrid approach is also applicable in different infrastructures build for high loads and big data processing. | ||
Lyapin A. A. Testing of programming modules for flight task calculation and control based on the source data prioritization. Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/611/Lyapin_rus.pdf The article proposes the diagram of computer-aided exploratory testing of calculation and control of the flight task software developed by State Rocket Centre “Academician V.P. Makeyev Design Bureau”. Calculation and control of the flight task software (ССFT software) is a key system of rocket complex and prepares for intercontinental ballistic missile’s flight-control system data, special automatics, and flight-control system of detachable elements. ССFT software consists of programming modules developed by engineers of State Rocket Centre and related organizations. Programming module (PM) is a functionally completed software implementation of CCFT particular task (algorithm).
To ensure quality and reliability every programming module should be debugged and tested in autonomous operation. Reliability of programming module is the probability the module operation without crash.
In this work the author suggests applying a method of computer-aided exploratory testing for debugging and testing PM from CCFT software. This method accounts for input parameters’ priority built on the basis of computational stability index of explored tasks.
The testing diagram accounts for programming modules’ potential crash. It is based on determination of input parameters’ priority. The author suggests employing priorities that are based on computational stability of tasks.
The testing diagram can specify the test data area variation and makes the best use of testing time resources. The diagram also performs qualitative evaluation of calculation and control of the flight task software’s functionality. This diagram is being used for CCFT software testing by engineers of State Rocket Centre. | ||
Anzheurov A. S., Denisova I. P., Kostikov Y. A., Pasisnichenko M. A. Numerical analysis of the new type retroreflector application effectiveness while laser ranging of a spacecraft . Trudy MAI, 2017, no 97, http://mai.ru//upload/iblock/dc7/Anzheurov_Denisova_Kostikov_Pasisnichenko_rus.pdf When laser ranging of a spacecraft the light impulse reflected from retroreflector , forms spot on the Earth surface, which center is usually located at a significant distance (from hundreds to thousands meters) from the station’s receiving telescope, due to the velocity aberration effect. Thus, the receiving telescope appears to be at periphery of the spot.
Due to the fact, that the electromagnetic radiation energy flow in the pulse decreases as distancing from the pulse axis to its periphery, only a small portion of the light energy hits the receiving telescope. Often, this portion is not enough to register the moment of the reflected impulse arrival at the laser station. To eliminate this shortcoming the Research and production Corporation “Systems of precision instrument making” suggested the retroreflector of a new type, in which maximum of intensity of the reflected impulse’ direction diagram was shifted from optical axis to periphery by coating the retroreflector edges with various coatings, so that the spot changed into a luminous ring. It allowed shifting the intensity maximum to about 1.2 arcseconds from the reflector optical axis with angular width at the level of half-power of about one arcsecond.
Mathematical modeling and numerical analysis of a new type retroreflector implementation effectiveness for laser ranging of high-orbit and low-orbit spacecraft were performed in this work. The conducted study revealed that ensuring the most favorable conditions for low-orbit spacecraft ranging (the orbit height of 300−550 km) in retroreflctor of a new type requires shifting of annular directional diagram maximum of the reflected impulse relative to the central beam not by 1.2 arc-seconds, but several times more, i. e. approximately by 9.7 arc-seconds. High-orbit spacecraft (orbit height of 6000−34000 km) for the same purpose must be equipped with retroreflectors of a new type, in which the maximum of the directional diagram of the reflected impulse is shifted relative to the Central beam by about five arc-seconds.
This means that at the stage of designing of each spacecraft the unique retroreflector of a new type should be developed and manufactured maximally effective for operation at the projected orbit. | ||
Ruslantsev A. N., Dumansky A. M., Alimov M. A. The stressed-deformed state model of curvilinear composite beam. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/ef2/Ruslantsev_Dumanskiy_Alimov_rus.pdf Polymer composite materials are applied in a wide range of aviation and space technology products. A lot of such products’ components are curvilinear beams that work on bending. However, in connection with pronounced property anisotropy, composed materials’ behavior in such components differs significantly fr om metals. While developing design technique, information is required on material’s working in these or that conditions. For this purpose, samples with shapes close to typical structural elements are tested, in which course the stressed-deformed state of these elements is studied. Classical tensile, compression and shear tests cannot fully demonstrate the behavior of multilayered composite materials. Bending tests can provide additional information that fully describes the behavior of the material. ASTM D6415 Standard describes the samples testing of a typical structural element. The radial stresses in the sample are determined at the end of the test. Based on the experimental data listed in the ASTM Standards, a conclusion can be made that the destruction occurs in the curved zone of the sample due to delamination. While composite structures designing, the interlaminar stresses should be taken into account, since the contact zone between the layers has a low strength and destruction can be caused by the delamination of the material. Thus, determination of internal stresses caused by interlaminar interactions during stretching and compression of layers is an important task. The model determining the stress state in a layered curvilinear composite beam is suggested. The model correctness is verified by comparing the calculated stress values and the results obtained by finite element modeling. It is shown that the discrepancy between the results does not exceed 5%. Calculations for curvilinear beams with cylindrical anisotropy of properties and for layered beams were performed. It is shown that maximum stress values are determined by the bending moment and geometric parameters of the beam. The most effective stress reduction can be achieved by reducing the curvature of the laminated beam. It was determined that the central part of a composite beam, wh ere delamination is most possible, was the most dangerous zone. Optimum relationship of the beam’ material strength in circumferential and radial directions was determined. Recommendations to increase the bearing capacity of curved beams were elaborated. | ||
Kalashnikov S. T., Mokin Y. A., Shvaleva R. K. On changes of pressure center position of a sharp cone with small surface variations under hypersonic flow-around. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/867/Kalashnikov_Mokin_SHvaleva_rus.pdf The problem of evaluating maximum possible changes in the position of the pressure center at small angles of attack and specified constrains on surface distortions of hypersonic vehicles in the form of sharp cones with small-parameter linearization is reduced to the math problem of a linear functional norm. The developed integral expression of linear functional, evaluating changes in the position of the pressure center for the shape variations is based on a semi-analytic method of differential locality hypothesis. The general integral expression of the preset functional norm in linear space of weak surface variations for the specified restrictive function is developed.
The validity of the developed analytical expressions being strictly in the class of sharp cones is confirmed by analyzing test examples for two possible types of linear surface variations and their linear combination. The first variation is related to a linear scale and the second one relates to a cone angle. The compliance of numerical results of analytical estimates of δx_{ƒ} to the exact result is taken as a criterion. The validity of the obtained analytical results for bodies close to a sharp cone shape is estimated by comparing with the results of numerical computations based on the solutions of inviscid Euler equations for models of perfect gas or equilibrium and dissociating air.
It is shown that the first variation of the sharp cone pressure center δx_{ƒ}
at the specified weak variation of its surface under supersonic and hypersonic flows at small angles of attack depends only on two dimensionless parameters: a cone angle θ_{k}
and relation of derivatives of its surface pressure coefficient. The integral dependence of the first variation norm δx_{ƒ} for a sharp cone on the surface variation δy(x) and the above parameters is developed. The integral dependence of the first variation norm δx_{ƒ} for a sharp cone is developed at the specified restrictive norming function ψ(x) for a set of admissible variations of the cone surface δy(x), which allows of estimating a scale of probable variations δx_{ƒ}
in indefinite-type conditions δy(x). The method to determine qualitative variation of the sharp cone surface, which is close to maximum possible variation δx_{ƒ} at the specified variation constrains δy(x), is pointed out.
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Bakhvalov A. V., Greshnyakov P. I., Gimavied A. G. Studies of hydraulic drive efficiency with discrete valve and switched inertia tube. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/72f/Bakhvalov_Greshnyakov_Gimadiev_rus.pdf For the last years, energy efficiency is one of the main and important issues in developing fluid power technology. The discrete method of regulation is of particular interest while the development of such systems, in which the fluid stream is alternately supplied to the hydraulic drive actuator. For this purpose, discrete action valves are used. They are relatively simple, reliable, insensitive to contamination, and possess low cost. The paper presents the mathematical model of the hydraulic drive for loads lifting, containing discrete valve and switched inertia tube. Employing a switched inertia device (inertia tube and discrete valve) in the hydraulic drive system allows increase efficiency of such system by 20-30% due to the inflow of additional liquid from the low-pressure line (so-called flow amplifier mode). As a result of dynamic processes simulation in MATLAB/Simulink package, transients occurring while hydraulic drive operation were calculated. The article analyzes the effect of the following parameters on the hydraulic drive efficiency: the discrete valve operation frequency in the pressure line, the pulse duty cycle, the diameter and length of the inertia tube. Regulation quality estimation is given in the movement of the output link of the hydraulic drive with a cargo on the set trajectory. It was established that for the hydraulic drive with the pressure in the pressure line of 15 MPa and a weight of the cargo up to 1000 kg, the use of a hydraulic drive scheme with discrete valve and switched inertia tube allows increase its efficiency by 17% compared to the throttle control. The recommended parameters for such system configuration are as follows: the discrete valve operating frequency is 40 Hz, the pulse duty cycle is 30 to 50%, the inertial tube diameter is 10 mm, its length is no more than 10 m. The diameter of the discrete valve hole in the pressure line should be sel ected fr om conditions for ensuring the required speed of the output link. The disadvantage is acoustic noise while using a switched inertia device. It is necessary to use a pulsation damper to eliminate it. The obtained results can be useful for selecting hydraulic drive schemes with a higher coefficient of energy efficiency. | ||
Vasiliev V. V., Lazarev V. V. Twin-fuselage aircraft: pro et contra. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/d48/Vasilev_Lazarev_rus.pdf The article analyzes virtues and shortcomings of the twin-fuselage aircraft configuration as applied to a passenger and cargo aircraft. It notes specifics of aerodynamic and weight perfection of the twin-fuselage aircraft. The peculiarities of aerodynamics and weight perfection of the twin-fuselage aircraft are noted. The article also reveals the differences between twin-fuselage aircraft configuration and the aircraft of traditional schemes. The main ones are the as follows. The aircraft increase of the moment of inertia relative to the longitudinal axis complicates the compliance with the Part 25 airworthiness for recovering the aircraft from a turn with the tilt of 30° and entering it into a turn of the opposite direction with the tilt of 30° within no more than 7 seconds. The emergence of specific natural modes of aircraft oscillations with the rotation of the fuselages in pitch plane with opposite phase. The advantages of unswept central part of the wing are asserted. Attention is drawn to the increase of the aircraft pivoting radius on the ground and the complication of aircraft control when the pilot’s line of vision is shifted from the axis of the runway. As twin-fuselage aircraft configuration has no advantages over traditional aircraft configuration, its use is advisable only for solution of specific problems. For example, developing a passenger aircraft with a passenger capacity exceeding 500 seats, or a multifunctional heavy transport aircraft for the cargo placing in two fuselages, as well as a hard cargo on the external sling between the fuselages. Existence of the fuselage of certified donor aircraft will provide technical and economic efficiency of the twin-fuselage aircraft. | ||
Boyko S. O. Methodology of spacecraft structural components position fine adjustment. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/372/Boyko_rus.pdf With significant increase of satellite structural components size specifics of their relative position adjustment occur, associated with singular masses separate by a certain distance and structural elements coupling them. All structural components are affected by various space factors, including temperature impact, which leads to satellite structure optimal geometric disposition changing due to deformations. The author suggests employing the six-degree-of-freedom adjustment actuator to ensure fine adjustment. To control the adjustment device movement the author suggests the methodology based on implementation of measuring machine, three measuring spheres and an algorithm for measurement results processing. Contacting the spheres in at least four points, the measuring machine computes the coordinates of the position of each sphere’s center, which defines the spatial position of the adjustment device upper base. Data spheres’ centers position control is performed at the initial position (prior to spacial movement performing) and end position (after spacial movement performing). Position determining technique consists in the following. Using the obtained coordinates, we determine the values of the three linear and three angular movements of the plane, formed by the centers of the three spheres. To determine the movemeents one should compute coefficients of coordinates’ transformation matrix for the displacement from the initial position to the end position. Analyzing theoretical (defined by control block) and actual (computed from co-ordinate measuring device data) values of the adjustment actuator spatial movement allows evaluate transmission errors for every degree-of-freedom. Specified errors led to satellite structural components relative offset in an area, which depends on their distance from each other. The proposed final adjustment methodology of structural elements and mechanical devices allows account for interaction of separate actuators in adjustment devise and structure of satellite geometry changing to achieve the specified parameters during ground experimental tests and on-orbit satellite functioning. | ||
Gordeev S. V., Kanev S. V., Suvorov M. O., Khartov S. A. Evaluation of high-frequency ion thruster parameters. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/894/Gordeev_Kanev_Suvorov_KHartov_rus.pdf There is an increasing need for low Earth orbiting satellites for various purposes. Such satellites are cheaper to put into orbit (for altitudes 160−300 km), and can ensure high-resolution for Earth observation. However, lowering orbit altitude means that atmosphere gases concentration and the aerodynamic drag force increase causing decrease in the spacecraft orbit lifetime. Electric propulsion thrusters could be used to counteract the aerodynamic drag. For example, the European Space Agency spacecraft GOCE operating in a near-circular orbit with altitudes of 250−280 km for more than four years used the ion thruster T5 of QinetiQ Company for aerodynamic drag compensation. This thruster used onboard xenon as propellant. When the whole amount of propellant was consumed, the vehicle began lowering and burnt in atmosphere. Application of atmosphere gases as propellant may substantially increase lifetime of low orbit spacecraft. This work focuses on the operation of high-frequency ion thrusters operating with atmosphere gases as propellant. Such thrusters may be used to counteract the aerodynamic drag of low Earth orbit spacecraft. Work processes in the ionization chamber of ion thruster were modeled. A mixture of atomic and molecular nitrogen and oxygen was considered as a propellant. During ionization each of these gases partially transforms in singly charged ions. The thruster characteristics, namely its thrust and consumed power were analyzed and compared to characteristics of the spacecraft from the viewpoint of its aerodynamic drag and solar panels power. The results of this work demonstrate the possibility of creation a low orbit spacecraft with high-frequency ion thruster operating with atmosphere gases as propellant to counteract the aerodynamic drag. | ||
Borovikov D. A., Ionov A. V., Seliverstov S. D., Yakovlev A. A. Analysis of the effect of additional axial stage of a compressor on characteristics of small-sized turbojet engines. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/33c/Borovikov_Ionov_Seliverstov_YAkovlev_rus.pdf The article is devoted to the analysis of changes in characteristics of small-sized gas turbine engines with a two-stage axial-centrifugal compressor instead of a single-stage centrifugal compressor, and analysis of the current level of cycle parameters of small-sized gas turbine engines. The work was performed by mathematical modeling, using empirical data. Initial stage of the work revealed that even a slight improvement of modern small-sized engines cycle parameters would lead to a significant improvement in the main characteristics of the engine. Models were developed with average parameters in their class: air flow of 650 g/s, gas temperature of 1100 °K. A number of assumptions was made: the efficiency was fixed for all units, except the compressor at the operation level of design mode; generalized characteristics of high-speed turbocharges and characteristics of single-rotor single-loop single-cascade jet engine compressors were adopted as the characteristics of compressors. For a single-stage centrifugal compressor, the compression ratio in the rated mode was adopted as 4 at the level of the leading serial analogues, and for an axial-centrifugal as 5.7. Analysis of the obtained altitude-airspeed performance revealed that by employing an axial-centrifugal compressor instead of a centrifugal one we can expect improvements of the main parameters (internal thrust, specific thrust, specific fuel consumption) of the engine up to 10−15% in the entire range of airspeeds and altitudes. Particularly, in the basic modes of flight of an unmanned aerial vehicle equipped with a similar engine, i. e. cruising (M = 0.8, H = 8000 m) and take-off (M = 0, H = 0m), thrust grew by 8%, and fuel consumption reduced by 12%. This result allows concluding that it is reasonable to use a constructive scheme of a small-sized engine with a two-stage axial-centrifugal compressor while developing new engines. | ||
Moiseev K. A., Panov Y. N., Moiseev K. K. Mathematical model of a two-link tractor moving on the dirt road. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/ffb/Moiseev_Panov_Moiseev_rus.pdf The article presents a mathematical model of a two-link object movement on the dirt road with periodic unevenness. This model may be useful for the suspension system development at the initial design stages. Mathematical models are presented for different viscoelastic characteristics of the coupling device. It studies the smoothness of the unit in resonant modes of motion of a two-unit tractor. The study of smoothness is based on the intensity curves, which are constructed using the amplitude-frequency characteristics. These characteristics were obtained from the solving the systems of differential equations by analytical matching method or numerical Runge-Kutta method. Matching method is very effective for dynamic systems studying if a differential equation does not exceed the sixth order. It is an organic combination of operator method and the method of variation of constants. Operator method allows construct the equation authorization for the original system of differential equations, and find coefficients of dissipation and frequency of free oscillations of the system under study. As for the method of variation of constants based on the solutions obtained by the operator method, it allows determine a particular solution of the original system of differential equations in the form convenient for analysis. The obtained results can be applied to ground-car mobile and crawler units, a well as aircraft while studying its landing or emergency landing. According to the obtained results the authors concluded that the improvement of the smoothness of a two-unit tractor when driving on dirt soil with periodic unevenness requires modification of the viscoelastic characteristics of the hitch mechanism, which, in its turn, alter geometric and weight parameters of the tractor. | ||
Alliluyeva N. V., Rudenko E. M. Mathematical method of objective function calculation and routing problems solving. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/9c1/Allilueva_Rudenko_rus.pdf A lot of tasks of unmanned aviation on observation of the objects, in the most general set up is reduced to route selection between the two benchmarks, which lead to mathematical problem of optimization on the graph. It is assumed herewith that the route is closed and passes through all ribs of the graph. The optimization task on the graph meant for calculating the set of closed routes of minimal length relates to the integer programming problem [1]. The goal of the work consists in solving the optimization problem on the graph leading to obtaining optimal closed routes (OCR). The authors suggest genetic algorithm (GA) as an optimization method. For its implementation the objective function of sevral variables was developed, which simplified significantly the program code and reduced the computation time. The objective function represents the sum of three functions. The first function depends on the edges of the graph, and penalizes edges and loops which do not belong to the graph. The second function depends on the Euler model of the original graph, i. e. the method of the graph reduction to the Euler type by adding multiple edges. The third addend depends on the vertices of the graph and accounts for their multiplicity. The minimum of the objective function is achieved on OCR only. The GA application allows obtain limited quantity of OCRs from a large variety of variants during finite time, which can be reproduced several times by using the group of the graph’s automorphisms. The presence of the OCRs variety allows planning the order of graphs fly-offs afield while solo and group flights, promptly regroup monitoring routes in consecutive and dispersed flight over various ribs and without intersection at vertices. | ||
Diveev A. I., Konyrbaev N. B. Quadrotor group control by variation analytical programming technique. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/020/Diveev_Konyrbaev_rus.pdf The article analyzes an applied problem of area monitoring with a quadrotor group. The problem solves in two stages. At the first stage, the problem of searching an optimal route for each quadrotor is solving. This problem is the problem for travelling salesman group in 3D space, and related to the class of computation tasks of NP-difficulty. Variation genetic algorithm is applicable for such task solving. This genetic algorithm employs the principle small variations of basic solution. All genetic operations perform on the sets of basic solution variations. The rate of convergence of the genetic algorithm depends on the obtained basic solution. At the second stage, the problem of synthesis of quadrotors control to ensure their movement along the routs obtained at the first stage is solving. To solve the problem synthesis of control the numerical symbolic regression method was employed, i. e. method of variation analytical programming, which allows finding mathematical expression for a control function. The arguments of this function are contained in the quadrotor state vector. The control function ensures an optimal mode of quadrotor stability relative to the point in state space. An example of control problem solution for two quadrotors group is presented. | ||
Terekhov R. I. The study of a regional airplane's emergency remote servo-control specifics in longitudinal channel. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/88d/Terekhov_rus.pdf In this article servo-control means the principle when control levers are coupled with their control tabs rather than main control surfaces. Control tab is a small surface located in control surface tail section. Its deflection causes the hinge moment occurrence, which moves the control surface. The purpose of the emergency servo-control consists in ensuring redundancy of a mixed flight control system. The study was conducted for regional aircraft with two independent hydraulic systems and two elevators for longitudinal adjustment and control. Two conventional electrohydraulic servoactuators (EHSA) provide each elevator deflection in the main control mode. Each elevator has a control tab with electro-mechanical actuator (EMA) for emergency control in case of both hydraulic systems failure, when all the EHSAs switch to damping mode. The estimated value of control tab’s own hinge moment is significantly less than elevator’s hinge moment. Such small-sized EMA of low weight could be used to control tab deflection. The description of elevator deflection dynamics includes the non-linear dependencies of both elevator’s and control tab’s hinge moments, damping force caused by EHSAs in damping mode, and elevator aerodynamic damping. After the loss of hydraulic power, the elevators move under the hinge moment. It could result inthe exceeding the operational values of angle of attack or normal g-factor of the aircraft. For smooth and safe transition between control modes, the control tabs in main mode should be controlled so as the elevator hinge moment close to zero. Furthermore, such deflection of control tabs allows reduce the EHSAs load during the flight. The handling quality of an aircraft being in servo-control mode depends on a considerable degree on the actuator damping coefficient. In the course of the study the acceptable range of actuator damping coefficient values necessary to provide the required handling qualities in emergency control mode has been determined. Flight simulator study with test pilots involved proved that aircraft handling qualities in servo-control mode ensured the safe flight continuation and landing. | ||
Kozlov A. V., Kozlova M. V., Skorik N. A., Sharonov A. V. Application of multispectral satellite imagery to monitoring of vegetation activity annual dynamics. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/b8b/Kozlov_Kozlova_Skorik_SHaronov_rus.pdf
The paper presents the results of application of multispectral images obtained from OrbView-2 and Envisat missions to monitoring of vegetation activity annual dynamics at 12 test sites in Volga-Akhtuba floodplain based on conventional FAPAR index over a decade since 1997, including drought summer season of 2006, as a part of a project conducted by N.N. Zubov State Oceanographic Institute for monitoring of Lower Volga. The territory under consideration extends over 9000 square kilometers, thus making the use of satellite imagery to be the only source of assessing the overall ecosystem state. Time series of FAPAR values for regular (non anomalous) years are being approximated by a single harmonic model function. This function then serves as a reference to analyze deviations of particular FAPAR values from it. To introduce stronger physical relation between reference model function and parameters of the environment we consider using public annual temperature data from weather stations of World meteorological organization in addition to satellite images. The two models, one with temperature variations included and one without these, are then calibrated and compared against each other at all test sites. Mathematical and physical rationale for both types of models and some visual examples of their calibration are given. Our study concludes that despite of the fact that using the temperature data improves the accuracy of vegetation dynamics model, this effect does not prove to be significant, while yet increasing demands in the amount of input data for analysis. Quantitative statistical results support the case.
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Malygin I. V., Belkov S. A., Tarasov A. D., Usvyatsov M. R. Machine learning methods in classification of radio signals. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/e4c/Malygin_Belkov_Tarasov_Usvyatsov_rus.pdf This paper is devoted to the issue of recognizing received encoded radio signal sequences. Traditionally, correlators or matched filters are used in communication systems to detect and process noise-like signals. These two models use a threshold detection parameter. The use of a neural network is proposed to improve the quality of signal recognition when the noise characteristics in an environment are unknown. The neural network is a non-linear model with a relatively large number of parameters which tests proposed examples during the learning phase and attempts to reproduce the relationship between them using the responses. To use the neural network, it is necessary to reformulate the original issue in terms of optimization. That is, to enter a quality functional, which will be optimized, and choose a method of optimization for the given functionality. To select the neural network parameters that achieve the optimum of the quality functional, the back propagation algorithm will be used. The stochastic gradient descent algorithm determined by the quality functional will be used to calculate parameter updates of the neural network. For convenience, only digital signals will be considered in this paper. Nevertheless, the method described in this paper can be applied to a continuous signal. The digitizing of a continuous signal will transform the task into one of signal detecting, which has been formulated above. In each cycle of the receiver’s operation, a signal is generated at its input. The signal is a sequence of fixed-length and can either be similar to the protocol-defined signal, or be significantly different. Therefore, the task can be formulated as a task of binary classification of the received signal in each cycle of the receiver’s operation as a valid signal and noise. It is assumed that the quality of recognition will be better than with the traditional methods because, during training, the neural network is able to memorize the special features of the noise and, consequently, use the obtained model at the signal classification stage. A diagram for an experimental stand is also provided in this paper that would allow for the confirmation of this assumption. | ||
Yanushkevich V. F. Radio-pulse signals interaction with anisotropic media above hydrocarbon deposits. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/95f/YAnushkevich_rus.pdf The article analyzes the interaction of electromagnetic waves in radio-pulse signals mode with the medium above hydrocarbon deposits. Tensor of the dielectric permittivity constant of an anisotropic medium over the deposit in the mode of radio-pulse signals is derived by means of a quasi-hydrodynamic approach using multi-particle electron-ion currents. The study was carried out based on the solution of the electron motion equation. Hilbert transform was employed to find the envelope and instantaneous frequency of the two acting signals. The components of the medium’s dielectric permittivity constant above hydrocarbons were analyzed. Selection of the radio-pulse signals’ frequencies was stipulated by determining characteristics of media over deposits at great depths compared to the earth surface. It is shown that the results of the study can be used to identify the environment over deposits by the nature and magnitude of the total and differential components of the dielectric permittivity constant of the anisotropic layer. The tensor of the dielectric constant of the anisotropic medium over the hydrocarbon deposit in the radio-pulse signals mode can be used to determine the electrodynamic characteristics of the medium above the deposit in a wide range of probed signals’ frequencies, dielectric permittivity and conductivity of the media. The studies can be applied to determine characteristics of the medium over the deposit under the propagation of electromagnetic waves with right and left-hand circular polarizations, which increases the informative value of the methods of contouring and the hydrocarbon deposits allocation. The propagation of electromagnetic waves with left-hand polarization while changing the dielectric constant of the medium leads to the alteration in the combination component with a change in the sign of the differential component. Thus, it can be used to develop methods of electromagnetic exploration, search and identification of hydrocarbon deposits. Electromagnetic methods of hydrocarbon search and identification can be updated due to the received information on objects through not only one or two information channels but also using larger quantity of them, which enables their boundaries to be identified against the background of the underlying environment with a sufficiently high level of certainty. The results of the study can be applied in geophysics search. | ||
Kuznetsov V. S., Shevchenko I. V., Volkov A. S., Solodkov A. V. Ensemble of Gold’s codes generation for direct-sequence spread spectrum. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/f64/Kuznetsov_SHevchenko_Volkov_Solodkov_rus.pdf The article considers generation of m-sequences and Gold’s codes employed in spectrum spreading systems. The goal of the article consists in ensembles systematization and search for all pairs of polynomials, forming Gold’s codes. Gold’s codes have a low level of cross-correlation between the sequences in the ensemble, which allows employ them for users’ separation in communication systems. Maximum number of users in the system depends on the number of sequences in the code ensemble. The classical method of e-sequences and Gold’s codes generation is representation of generator in the form of linear-feedback shift register (LFSR), since this approach ensures the simplicity of algorithm implementation to a digital unit. Employing the classical generation method (based on the generator representation in the form of LFSR) becomes non-optimal while generating ensembles of long sequences (N > 2^{10} – 1). The generation time of all Gold’s code pairs grows significantly due to the number of all possible combinations increasing while sorting pairs of sequences. The Gold’s code generation method using the Berlekamp-Massey algorithm and decimations defined for the codes under consideration generation was selected. Based on this algorithm the authors developed the program for searching the preferable pairs returning the Gold’s code under addition modulo two. The main goal of the program is generation of all volume of the Gold’s code family. The obtained results were checked by evaluation of the value and number of cross-correlation peaks of the two tested sequences. The obtained results can be implemented in the systems employing direct spectrum spreading, such as CDMA. The paper presents the number of binary polynomials and the list of the number of unique polynomial pairs for the code length up to m ≤ 16, forming Gold’s codes. The full list of primitive polynomials for the code length of N = 2^{10} – 1 is presented. The example of preferable pairs of primitive polynomials of m-th degree (m = 5) is given. The number of pairs polynomials for generating Gold-like codes for the degrees of m = 8 and m = 12 of code seeds is given. The obtained results can be implemented while developing communication systems with users’ separation for obtaining overall Gold’s ensemble and studying the properties of the obtained sequences and their derivatives. | ||
Bakhtin A. A., Omel'yanchuk E. V., Semenova A. Y. Analysis of present-day capabilities of organizing ultra-high-speed satellite radio links. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/838/Bakhtin_Omelyanchuk_Semenova_rus.pdf According to the «Digital Economy of Russian Federation» program, new requirements for wireless communication technologies, including technologies for remote sensing systems (RSS) are now being put forward. The share of Russian remote sensing data in the total amount of remote sensing data used in Russian geographic information systems will grow steadily and reach 90% by 2024 [1]. At the same time, it will be necessary to ensure complex implementation of the overall technical capabilities of the manifold of spacecraft and ground infrastructure in order to obtain the large amount of RSS data of the required quality [2]. The article considers technical characteristics of modern remote sensing spacecraft from the viewpoint of radio downlink organization. It presents the problem of the discrepancy between the current throughput rate of the satellite channel and the volume of transmitted information from the remote sensing. The existing radio RSS links keep on employing various frequency ranges depending on the requirements for the communication system. However, the X-band and K-band have the largest bandwidth for RS data transmission. It is shown that the standard transmission rates in the X-band are 150 Mbps and 300 Mbps employing standard modulation and coding methods, while maximum throughput rate of the satellite radio channel of some foreign satellite communication systems reaches 1 Gbps [3]. Future methods and modern trends for increasing throughput rate were determined based on the analysis of modern satellite transmitters for remote sensing systems: methods of modulation and error control coding in the X-band , as well as the possibility of transition to the K-band. The article shows that in practice the use of the K-band at the present time does not allow achieving the required advantage in radio link capacity. This, in particular, is caused by more stringent requirements for the implementation of on-board and ground-based equipment imposed on the transmitters in the K-band, as well as due to the higher losses in the propagation of radio waves in this range. As the main recommendations for the development of high-speed satellite radio links equipment, we should indicate implementation of modulation and coding schemes with high spectral efficiency, the use of several channels and the adaptability of the communication system. The authors propose a modulation scheme with high spectral efficiency [23] as well as the implementation of four-channel transmitter scheme [24] allowing combine X- and K-band transceivers to achieve larger total throughput rate of the radio link. Development prospects in this area should also include the development of an element base in the K-band of frequencies and an increase in the accuracy of antenna guidance for a polarization decoupling employing. | ||
Vovasov V. E., Betanov V. V., Turlykov P. Y. Navigation receiver and accelerometers integration for coordinates and orientation evaluation of highly-dynamic objects. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/b18/Vovasov_Betanov_Turlykov_rus.pdf One of the effective methods of noise immunity improving is implementation of integrated inertial-satellite systems. NAP GNSS with INS integration will allow eliminate the existing shortcomings of each system separately. Typically, integration involves the joint processing of pseudo-range, pseudo-phase and pseudo-velocities, obtained by the GNSS receiver, as well as vectors of angular velocities and accelerations derived with non-stationary Kalman filter, which will be called the Kalman filter type (KFT). Highly dynamic object is characterized by the presence of jerking while moving. The jerking is customarily understood as the discontinuous change of the third derivative of a coordinate with respect to time. To ensure this requirement it is necessary to employ navigation receiver with signal phase tracking system with the third order astatism. Employing a navigation receiver with conventional second order filter within the system of signal envelope tracking just enough for delay tracking. Since the exact model for integrating equations of orientation is based on the model proposed by Bartram, it complicates the use KFT, as it requires rather complex notation of derivatives in analytical form. The state vector of the filter should include accelerometers’ instrumental error, namely the rate of zero drift and scale factor error of each, which expands the state vector, and thus reduces the potential accuracy. Besides, the use of high-speed gyroscopes requires a priori orientation setting. In this regard, we suggest using no gyroscopes, positioning accelerometers to the phase center of navigation receiver antenna, and rotating herewith the frame with mounted antenna and accelerometers in a prescribed manner. It is necessary for orientation determining in the event of uniform movement of the object, i.e. when the measurement of the accelerometers is close to zero. Integration of these devices, each of which possesses the ability to determine positioning, gives the system a new feature, namely orientation determining. In this case, the KFT forming-up with this type of integration does not cause mathematical difficulties, and adaptive KFT element in use allows tracking course maneuvers of the object, while frames rotation allows orientation estimating even with rectilinear and uniform motion of the frame’s center. | ||
Erokhin V. V. Multi-criteria optimization of the trajectory of an aircraft in the augmentation area of the satellite navigation system. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/941/Erokhin_rus.pdf
A promising trend for improving organization and management of air traffic is the implementation of the concept of communications, navigation, surveillance and air traffic management, developed by the international civil aviation organization. This concept is based on the principles of broadcasting automatic dependent surveillance (ADS-B), which is a digital system for airborne transmission of flight path parameters by data of the global navigation satellite system (GNSS). To solve the problems of high-precision positioning and of flight safety, a ground-based augmentation system is used. When controlling the flight path, the aircraft position relative to the ADS-B ground station changes, thus affecting the Position Dilution of Precision (PDOP). In addition, when the distance from a local area augmentation system (LAAS) increases, the effect of decorrelation factors on the compensation of systematic errors increases as well. | ||
Klenov E. A. Algorithms and software for competitive analysis (on the example of aerospace industry objects). Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/d7e/Klyenov_rus.pdf Solving problems of the competitive analysis refers to the modern theory of decision-making. Decision makers should have necessary and sufficient information on new technologies in the industry, key competitors, potential risks, etc., as well as have time to process it and take optimal decisions. The goal of this work is developing of competitive analysis tools that is methodical, mathematical and software systems for supporting decision-making based on global competition modeling on the major stages of the life cycle of aerospace industry high-tech products. The article suggested for the first time an extension of the classical model of analysis of M. Porter’s five competitive forces, namely, a model of global competition. It also proposed methods for competitive strategy designing and forecasting the state of the industry markets based on of the behavior of intelligent agents, game theory and decision-making theory, methods of analysis of the competitiveness of high-tech product. Among the obtained results are the following:
The developed models, algorithms and software are used for the analysis of global competition for existing businesses of the aerospace industry and has shown its effectiveness. | ||
Mikhailov N. A. Development of an algorithm of a group of unmanned aerial vehicles evolution for signature reduction. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/e5e/Mikhaylov_rus.pdf For a long time the work has been underway on the development of the systems defending from small-sized unmanned aerial vehicles (SUAV) [1-3]. Modern unmanned air systems are capable of successfully overcoming the enemy’s air defense systems when used singly, [5], but the use of SUAVs group significantly increases the probability of their detection, due to better group’s visibility and less maneuverability compared to a single SUAV. The complexity of SUAV detecting is associated with a small value of radar cross-section (RCS) in radar observation range. In the optical and infrared observation ranges, the small sizes of SUAV complicates their detection as well. However, there is information on developing the control system for enhancing RCS for a group of missiles or UAVs [4]. One of the current problems of multiple SUAV’s application consists in reducing the group’s visibility in optical range when passing the air defense systems. As it is noted in [6], the visibility can be reduced by «reducing of the aircraft size». In this case, regarding the multiple SUAV’s application, we should speak about reducing the total area occupied by SUAV’s group in the image. An appropriate SUAVs group regrouping to reduce its visibility can solve this problem. This paper demonstrates how various groups’ readjustments could reduce their visibility. Various scenarios of the group entry into the scope of the enemy’s air defense systems were considered. A comparative efficiency analysis of various staffed formations was carried out. An algorithm providing for the operational reconstruction of the drone’s group, oriented to implementation using the Pixhawk autopilot was developed. Computer simulation using the model of autopilot and drone, which showed the operability of the proposed algorithm, was performed. | ||
Sirotin A. N. On special cases of a problem of an optimal control of angular movement of symmetric spacecraft stabilized by rotation . Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/ee1/Sirotin_rus.pdf Stabilization by rotation and stabilization of a spacecraft relative to the three axes are the main methods employed to maintain the exact solid body orientation. The idea of rotation stabilization is based on the application of a gyroscopic effect. The advantage of this method, compared to the other approaches, consists in simplicity and the lack of a prolonged active rotation period to maintain orientation in a certain direction. Rotational stabilization was being employed for a large number of foreign and Soviet/Russian spacecraft. Application of rotation stabilization for passive control is relevant for spacecraft with limited resources. However, the shortcomings of the passive stabilization method are also well known and are associated mainly with the problem of the exact reorientation of space antennas and optics. Thus, frequently used maneuvers for angular motion lead to the need to resort to solving problems of controlling the exact reorientation in three-dimensional space. The article studies the problem of angular motion optimal control of a rigid body by stabilized rotation. The efficiency criterion of is a minimum of energy costs. Compared to the general problem of reorientation and rotation control, the problem of bodies with stabilized rotation from the mathematical viewpoint is somewhat simpler. It is explained by reduction of dimensionality and complexity of the corresponding nonlinear equations of the system. Nevertheless, the problem of controlling joint reorientation and rotation remains complex and nonlinear. This, in turn, does not allow obtaining the required analytical result at the given time. Therefore, the purpose of this article is to obtain a characterization of extremal trajectories. There is a possibility to study in detail the problem of zero stabilization by rotation, when the projection of the angular velocity on one of the axes is identically zero. | ||
Vasilyev B. E., Magerramova L. A., Kolotnikov M. E., Golubovsky E. R., Volkov M. E. CIAM data bank on materials structural strength. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/83a/Vasilev_Merrogamova_Kolotnikov_Golubovskiy_Volkov_rus.pdf The design of a modern aircraft gas turbine engine (GTE) is associated with numerous calculations of the stress-strain state, strength and dynamics of the engine components and parts. It involves several processes, including substantiation of the main components sources, certification, analysis of the defects origins detected while operation and implementation of measures that can prevent the defects occurrence. Thus, the design procedure requires a complete set of data on the structural strength (realized in the course of the design) of the materials used. This paper presents the results of the long-term work in CIAM on the development of the database (DB) for information storage on the structural strength of the metal alloys used in manufacturing of the main and critical parts of an aviation GTE. The DB contains characteristics of a large number of materials obtained from experiments on 10000 specimens (more than 120 titles). Knowing these characteristics is necessary to perform calculations of the static strength and cyclic durability, dynamic characteristics and life of the GTE parts in a wide range of loading and operation conditions. The DB is based on the “Granta MI platform” software and consists of several sections containing reference information, experimental results, statistical processing results and characteristics for calculations. A description of the database structure, its functional capabilities and user interaction features is provided. A structure has also been developed for the DB section designed for samples made by using additive manufacturing. The developed CIAM databank on the structural strength of materials corresponds to current global analogues and can be used by the aircraft engine industry to calculate strength and dynamics, as well as to examine defects. | ||
Aksenov A. Y., Zaytseva A. A., Kuleshov S. V., Nenausnikov K. V. Possible landing support variants while unmanned multi-rotor flying vehicle's off-line control . Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/e88/Aksenov_Zaytseva_Kuleshov_Nenausnikov_rus_.pdf The paper analyses the problem of a small multi-rotor UAV control in various flight modes. The modern tendencies of control systems design for self-supporting UAVs assume employing methods allowing decrease the level of the spacial position uncertainty and surrounding conditions of the UAV itself without external pilot’s (operator) engagement. With this, the standard technological solution for a certain number of critical flight phases, requiring precise spatial positioning and control (such as take-off, hovering over landing site, and landing) does not exist. These phases require more precise UAV’s control, due to the necessity of holding it in a specified point in space. The presented article analyses principles of auto-take-off-auto-landing systems design, based on computer vision (CV) methods implementation, and considers specifics of markers employing. The article analyses the existing auto-take-off-auto-landing systems without global positioning implementation. It suggests an approach to the auto-take-off-auto-landing system design based on computer vision, for an UAV of a multi rotor or a helicopter type. Three types of the system components mutual arrangement were considered and analyzed, and merits and demerits of each configuration were formulated. The article shows that with any cameras positioning within the auto-take-off-auto-landing system, it is necessary to employ markers to facilitate localization of the key points the UAV or a landing site by the CV systems. Various methods of markers’ positioning and realization of marker labels, depending on marker’s position were analyzed. Markers on the landing site can be realized by the following methods: contrast image of some pattern, liable to identification by the CV methods; lights, remotely controlled by the processor; colored or infrared LEDs, operating in continuous or pulse mode. Variants of marker labels on an UAV are as follows: colored or infrared LEDs, operating in continuous or pulse mode; lights, remotely controlled by the processor; the system of angle reflectors and illuminator; contrast image-pattern (including a fuselage shape). The studies revealed that the controlled markers mode was preferable in all cases, when formation of a control channel between an UAV and landing system was possible. Further research will be devoted to development of software for auto-landing system based on obtained marker implementation recommendations. | ||
Lukin V. N., Nikitin I. K. Video sequences retrieval algorithm. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/964/Lukin_Nikitin_rus.pdf The article focuses on the algorithms of the event detection in content-based video retrieval. Video has a complex structure and can express the same idea in different ways. This makes the task of searching for video more complicated. Video titles and text descriptions cannot give the whole information about objects and events in the video. This creates a need for content-based video retrieval. There is a semantic gap between low-level video features, that can be extracted, and the users’ perception. The task of event detection is reduced to the task of video segmentation. Complex content-based video retrieval can be regarded as the bridge between traditional retrieval and semantic-based video retrieval. The properties of video as a time series are described. The concept of anomalies in the video is introduced. A method for event detection based on comparing moving averages with windows of different sizes is proposed. According to the classification given at the beginning of this article, our method refers to statistical methods. It differs from other methods of low computational complexity and simplicity. The video stream processing language is proposed for function-based description of video handling algorithms. So, our method is formulated in the form of a declarative description on an interpreted programming language. Unfortunately, most of the existing video processing methods use exclusively imperative approach, which often complicate its understanding. Examples of this language implementation are given. Its grammar is described either. As it was shown by the experiments, the implementation of the proposed video events retrieval method, unlike their counterparts, can work for video streams as well with a real-time and potentially infinite frame sequences. Such advantages within low computational requirements make implementation of the method helpful in aviation and space technology. The algorithm has some disadvantages due to necessity of parameter selection for particular task classes. The theorem on near-duplicates of video is formulated at the end of the article. It asserts the near-duplicate videos express the same sequence of phenomena. | ||
Astapov V. Y., Khoroshko L. L., Afshari P. .., Khoroshko A. L. Application of CAD system for simulation and study of magnetic-pulse welding of the tubular structures. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/d62/Astapov_KHoroshko_Afshari_KHoroshko_rus.pdf Liquids and gases are widely used in aircrafts structures as energy carriers for propulsion systems, in hydraulic actuators and pneumatic boosters, and as coolants, lubricants or in pneumatic actuators to ensure vital activity of a crew and passengers. The presence of liquid and gaseous media onboard an aircraft leads to the necessity of employing piping systems. One could hardly imagine fuel and pneumatic systems of modern aircraft without pipelines and automatic equipment, regulating their delivery. At present, aircraft and helicopter pipeline systems count thousands of tubular structures joints. The aggregate length pipelines herewith is hundreds plus meters. There are various pipelines with diameters sized from units to several tens of millimeters from various materials – aluminum, titanium, steel and other alloys. The great majority of them herewith are various fixed junctions with tips, flanges or pipes between each other. The presented article is devoted to methodology development of automated design of both aircraft pipelines structures in 3D space, including various complex pipeline structures, and modeling the process of magnetic-pulse deformation and formation of fixed junctions of pipelines between each other from homogenous and heterogeneous materials using CAD system. For this purpose a computer solid-state simulation is used together with solving the dynamic problem of junction formation while varying various structure parameters, characteristics of materials and parameters of magneto-pulse deformation. On creating pipelines parts and further modeling of the magnetic-pulse deformation the Autodesk Invertor design environment was used. To model 3D objects which axisymmetric tubular workpieces of junction structures can be related to, various tools for geometry creation were used. While modeling the process of high speed deformation by pulsing magnetic field and formation of junctions the Autodesk Simulation Mechanical 2015 program, allowing effectively try out tubular workpieces assembly with the required surface shapes, parts sizes and specified characteristics of materials, was used. This simulation of the process of connecting tubular workpieces by pressure of pulse magnetic field allows select effective modes of deformation in terms of junction quality to form the required parameters of welding in cold state in contact zones of tubular structures. | ||
Ye W. T., Markin L. V. Discrete models of ensuring service areas and automated layout of aircraft. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/87e/E-Vin-Tun_Markin_rus.pdf The article considers the solution of a problem of the instruments automating layout design in the aircraft technical compartments. An additional requirement to the layout is the ensuring of service areas, which is understood as assembling or servicing ease of the equipment. The purpose of this study consists in developing methods and algorithms, providing access to assembly tools and the workspace while installation and maintenance of the already installed equipment. The gist of methodological approach employed in this study consists in modeling of spatial movements of the equipment necessary for performing maintenance work on this equipment. The set of equipment necessary for its assembling and dismantling (screwdrivers, wrenches, special installation tools etc) is determined for each unit. On its basis the geometry model of this equipment is formed. Further, all necessary movements for both the assembly process itself (such as a wrench rotational motion) and the process of installation tools delivery to the work point are determined. Thus, modeling of this process is rather complicated task of geometric modeling. Solving method is geometric modeling of both placed objects, and mounting hardware and the trajectory of its motion. Thus, both the mounting hardware and motion trajectory are considered as assembling objects. Intersection with other objects is unallowable. Geometric receptor models, discretizing the installation area, are used a modeling method. Selection of receptor models is stipulated by the fact that a solid-state model of the entire positions of the assembling tools in the course of their delivery and operation is utterly geometrically complex. Based on heuristic algorithms the possible trajectory of assembling tools delivery to its point of use is used. This trajectory represents a solid-state model of the instantaneous movements of the installation tool along the sel ected path. Based on the receptor computational model the authors developed the procedure for determining the movement trajectory of the installation tools, or the finding of fact of impossibility to service the concrete object, which indicates the poor (low-tech) design decision. The disadvantage of the receptor geometric model is that it is not a initial model for a design engineer. The initial information for the designer is parametric model containing of the primitive's description and its main parameters values, which can easily determine fr om the drawing. Therefore, the necessity in extra program module “Parametric model”↔“Receptor model” arises. Thus, we can consider receptor model as an “intrаcomputer model”. The advantage of the receptor model, determining its selection for our studies, is the ease of determining the condition of intersection of geometric objects described by this method, which cannot be described analytically. For instruments in need of servicing three receptor models are being developed: geometric shape of assembling tool, its delivery trajectory to the point of use, and working space where this tool would be used. With this, the database is used, determining the necessary installation tool for each type of the object in servicing. The type of the assembling tool is determined by the type of attachment this object in aircraft structure. The installation tools acceptable for the specified operation are ranked also according to productivity and operational comfort. Thus, the installation tools are checked on workability by preferability. The preferability is determined by productivity and operational comfort of installation tools acceptable for work. Thus, a solid state geometric object of extremely complex shape lacking analytical description is developed. If this object can be accommodated among the already installed aircraft instrumentation, this equipment can be serviced, otherwise– it cannot be serviced. The possibility of rather easily determining the fact of intersection of all objects of the scene described by receptor models, is the substantiation of selection in our studies of receptor method of geometric modeling. The authors developed the software in C# implementing the described receptor geometric models allowing evaluate the possibility of servicing the already installed equipment in the aircraft technical bay. | ||
Buslaev S. P., Vorontsov V. A., Grafodatskiy O. S. Problems of Venusian spacecraft landing modeling for various soil-analogues. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/4fe/Buslaev_Vorontsov_Grafodatskiy_rus.pdf The subject of this study is the problem of Venusian analogues-groups simulation, which arises anew while planning the future spacecraft expeditions to new areas of Venus. Here, under the analogs-soils, we imply mathematical models or purposefully made in terrestrial conditions artificial physical models of soils to substitute natural soils of Venus. These analogs-soils are employed for landing dynamics calculation and testing of a spacecraft landing on soil. The goal of this work consists in analyzing the problems while developing new analogues and the experience of employing analogs-soils in JSC “NGO Lavochkin” during the by-gone Soviet spacecraft “Venus 9-14” and “Vega 1-2” development. At present, planetologists еtake interest in studying new areas of Venus, where tectonic processes occurred earlier. They expect to bump into ancient rock yield of the planet in these areas, which wlould help to elucidate the history of Venus evolution. On June 15 1985 the Vega-2 spacecraft landing had completed a fifteen-year series of successful landings of ten Soviet spacecraft on the surface of Venus. Structurally, the landing mechanism was attached to a cushioning toroidal shell, which was deformed and absorbed the kinetic energy of the spacecraft, while hitting the surface. Analysis of radar images of the Venusian surface revealed that all Soviet spacecraft landed in the areas with predomination plain types of Venusian terrain. The terrain relief of this area differs from the one, with the new landing areas. The area with the new landing areas was called “tesserae”, which in Greek means “tile”. The “tessera” relief represents an aggregate of intersecting ridges and furrows, the ridges’ height herewith can reach up to 1–2 km, the ledges – up to 1 km, while slope angles of the surface can reach up to 30 degrees. The spacecraft landing practice was performed at the JSC “NPO Lavochkin” on both physical and mathematical test benches. The article lists the objectives of physical tests. Models of deformable and non-deformable soils were employed for landing practice. The article presents the description of the physical test bench, which was employed for developing mathematical model of a spacecraft penetration into deformable Venusian soil. It also presents the description of mathematical models of landing on various models of soil. The work lists the sequence of models simulating the spacecraft hit with the soil. These models are listed by the degree of their complication – from a flat impact on an non-deformed flat surface to a spatial impact on an elastic-viscous-plastic medium with a complex relief. Finally, the article drew conclusions that two most common basic problems exist for soil-analogue: – Selection of hypothetical soil of Venus in the “tesserae” area; – Selection of Earth soil-analogue, corresponding to the hypothetical Venusian soil. The relief in new regions of Venus is much more complicated than the terrain in which Soviet vehicles landed, so these problems are of particular importance for the safe landing of spacecraft. | ||
Emelyanov A. A., Malyshev V. V., Smolyaninov Y. A., Starkov A. V. Formalization of the problem of operative target functioning of diverse spacecraft for remote Earth probing. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/8cc/Emelyanov_Malyshev_Smolyaninov_Starkov_rus.pdf The existence of a steady and rapidly growing demand for remote probing data (RPD) stimulates organizations operating the domestic spacecraft grouping (RPD) and ground infrastructure to seek the ways to improve the system’s efficiency. Presently, the topical problem consists in the lack of multi-objective planning of intended use of aggregate information resource of diversified orbital grouping, insufficient level of automation, the lack of means for feasibility calculation of consumers’ applications, insufficient operative planning horizon, which does not allow rational employing of a spacecraft technical capabilities. The article considers the issues associated with formalization of up-to-date task of target grouping operations planning for various types of remote probing spacecraft and development of a set of interrelated mathematical models necessary for specialized software developing that allows create optimal control programs for surveying in a realistic situation at a given planning interval. An approach to the solution of the planning problem for a spacecraft group of the one type is proposed. The initial set of surveying objects is being divided into subsets according to the type of shooting equipment specified in the consumer’s application, and by the geometric parameters of the survey areas. Models for changing the occupied volume of the on-board storing device and changing the orientation of the line of sight of the camera are presented in the form of discrete equations of state. The basic formulas necessary for determining the moments of possible shooting of point and area objects, determining the boundaries of possible radio communication intervals with ground receiving points of information, checking the conditions of shooting by illumination and the amount of clouds over the survey area are presented. A technique for calculating the area captured in a single survey of a specific spacecraft and the area captured by a spacecraft group in the planning interval is described. As a model of the plan, a pair of interrelated programs is considered: a time sequence of switching on and off the survey and radio transmitting equipment of the spacecraft of the group and a piecewise linear program for reorienting the line of sight of the camera. A criterion for the effectiveness of the plan is introduced in the form of a linear convolution of the normalized information efficiency and the relative costs of the onboard resource of a group of similar spacecraft. The solution of the task of planning the target functioning of a grouping of diverse types of spacecraft is reduced to the sequential solution of planning problems for groups of the same type of spacecraft that are part of the initial grouping. | ||
Lavrentyeva M. V., Govorkov A. S. Objects identification in e-model structure by identified formal parameters in the design and engineering environment. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/1f7/Lavrenteva_Govorkov_rus.pdf The study relates to the field of design automation and technological preparation of production in aircraft construction. The authors propose a technique for a product e-model objects’ structure identification by formalized parameters. For this purpose, the technique for contour pattern recognition, allowing identify geometric primitives bounding the surfaces, that form contours of each structural element, is employed. Thus, the necessity to develop structural geometric model of a product arises. It is necessary to identify hereafter the formal parameters of a part structure objects. The article considers the sequence of work with part’s e-model, which employs production rules, theory of sets elements, and apparatus of mathematical logic. The obtained structural and technological parameters of a part allow qualify it to a certain type, i. e. identify. Identification of a part, its structure and data on its coupling face allows define technological parameters, which structural form sets the geometrical requirements to basing. The article presents several basic rules for establishing the relation between individual parts, which can be used while a part processability evaluation, development of routes of producing and assembling, as well as technological equipment design. Thus, recognition systems implementation will significantly increase production efficiency by structural and technological problems solution unification. It will serve as a platform for intelligent systems of decision making of various directionality within the industry, which will allow decrease the effect of human factor while decision making due to formal criteria employing. Recognition systems implementation will allow ensure competitive products’ manufacturing with product’s structure with high target manufacturing and operating processability indices. The project is based on idea of technologist’s knowledge formalization, and developing on its basis the system of decision-making support. It will allow reduce the number of errors while performing technical control of the product while production start-up, and decrease production costs due to analyzing several design solutions and selection of composition-optimal structural elements with the specified level of processability and cost. The project is flexible while adjusting, with the possibility of implementation at various machine-building enterprises. | ||
Zanin K. A. Developing of a model of spacial resolution evaluation of a synthesized aperture space radar. Trudy MAI, 2017, no 96, http://mai.ru//upload/iblock/63d/Zanin_rus.pdf At present, there are contradictions in the formulation of the indicators of resolving power of synthetic aperture radar (SAR). Developers of SAR equipment usually suggest evaluate the resolution through the width of the profile of the scattering functions (hardware function). This definition simplifies the commissioning of the target equipment, but does not take into account the resolution relationship with the radiometric characteristics of the X-ray diffraction pattern, the background signal of the underlying surface, and random synthesizing errors. The inflated expectations of the consumers of radar information quality come into conflict with the requirements of the design specifications formulated by the developer of the target equipment based on their parochial interests. As a result, to formulate the requirements of the design specifications, it is necessary to develop methods for evaluating the quality of the radar image (SAR) that account for the characteristics of SAR. The article suggests an improved method for estimating the spatial resolution of a synthesized aperture radar, based on the condition that the modulation amplitude exceeds the signal equivalent to noise. The modulation difference is evaluated with account for attenuation of the spatial frequencies of the complex scattering coefficient on the SAR information path. To evaluate the resolution, the author suggested to employ two types of test objects with harmonic amplitude and phase modulation. Mathematical relationships determining the resolution equation through the spatial function of amplitude modulation transmission by the radar information path are considered. Analysis of the image formation specifics in radar complexes compared to optoelectronic ones was carried out. The article shows that the SAR provides spatial resolution about twice as low as the limiting value determined by the half-width of the hardware function. An improved method for determining the space radar’s resolution capability with account for the synthesized aperture formation specifics and random errors, is suggested. The proposed model of a test object with harmonic change in the complex amplitude or phase of the reflected signal allows relate the resolution capability of the SAR with its radiometric characteristics and reflection from the underlying surface. The function of modulation transmission of the amplitude and phase of the information path of the PCA for harmonic test objects was obtained. The properties of the amplitude modulation transfer function dependence on the spatial frequency made it possible to explain certain characteristic properties of the radar compared to optical images. The article shows that the SAR ensures approximately the same spatial resolution for the amplitude and phase harmonic modulation of the object scattering function, which is approximately two times worse than the limiting one. Increasing the contrast of the object to absolute values slightly improves the resolution up to 1.6 times. In case of low-contrast objects, the amplitude modulation is transmitted without distortion; the resolution capability is determined only by the realized signal-to-noise ratio with a resolution of 2.5 times worse. If an object is observed against speckle noise, the resolution of the SAR drops three or more times. | ||
Yudintsev V. V. Spatial motion model of Yo-Yo Mechanism. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/585/YUdintsev_rus.pdf The article considers the spatial motion of the Yo-Yo mechanism. When employing the Yo-Yo mechanism for an angular velocity damping of an object performing complex spacio movement, the effect of this movement on the operation of this mechanism should be accounted for. As an option of Yo-Yo mechanism implementation, which assumes an object’s complex spatio movement, the author considers implementation of a mechanism as a part of autonomous docking module meant for capturing space debris’ objects. After the docking module separation from the space tow and its docking with a space debris object, it is possible to use the Yo-Yo mechanism for an object’s longitudinal angular velocity damping.
To analyze the spatial motion effect fn the object, on which the Yo-Yo mechanism is installed, on the movement of mechanism’s elements (wire ropes with loads) a mathematical model of the spatio motion was developed. Besides the angular motion of an object the model supposes the location of the plane of the wire ropes reel-out at a distance of an object’s center of masses, as well as the possibility of asynchronous movement of the mechanism’s wire ropes. To form the equations of motion, the Lagrange formalism was used. Equations were set down for each phase of the Yo-Yo mechanism motion.
The performance of the mathematical model is demonstrated by several numerical examples of the of the angular velocity damping of the debris’ object of a prolate and oblate type in terms of the ratio between the principal moments’ of inertia values. It is shown that the determining factor affecting the motion of the wire ropes of the mechanism is the transverse angular velocity of the object. The initial transverse angular velocity of the carrier leads to the exit of the Yo-Yo mechanism wires’ from the plane of the wire ropes reel-out, which can lead to disruption of its operation. The Yo-Yo mechanism can be used as part of an autonomous docking module to decrease the space debris objects’ angular velocity, such as spent orbital stages of carrier rockets with a longitudinal moment of inertia less than transverse moments of inertia. | ||
Kuznetsov M. M., Kuleshova Y. D., Reshetnikova Y. G., Smotrova L. V. Occurrence conditions and high-speed overlap effect value in shocked gases' mixture. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/96c/Kuznetsov_Kuleshova_Reshetnikova_Smotrova_rus.pdf In the previous articles the authors formulated two theorems on the high velocity translational non-equilibrium in a shock wave of a one-component (ordinary) gas. It was noted herewith that the proofs of those theorems in case of shocked gas mixture required overcoming of several significant difficulties. The main difficulty consists in the fact that bimodal distribution of molecules velocities in gas mixtures cannot be used without doubt to determine the structure of a shock-wave, as it was done for the ordinary gas. As a rule, the area of applicability of the classic Tamm – Mott-Smith bimodal distribution with constant approximation of the auxiliary macroscopic velocities and kinetic temperatures for the groups of molecules in the supersonic and subsonic “wings” of such distribution is limited by the small values of concentrations of one of the mixture’s components. Only in this case it is possible to keep all the advantages of the bimodal approximation of partial distribution functions in binary gas mixture to obtain a simple analytical solution for shock wave structure. That is why obtaining necessary and sufficient conditions for high velocity translational non-equlibrium for arbitrary values of gas mixtures’ component concentration becomes much more complex. The paper presents rigorous formulation and substantiation of these conditions. These conditions are applicable to the case of variable auxiliary approximation macro parameters of “hot” wing of a binary gas mixture bimodal distribution. At the same time, the values of auxiliary macroscopic velocities and kinetic temperatures for groups of molecules in subsonic «wing» are kept constant. In binary gas mixtures with distribution functions for both the light and heavy components three types of functions of molecules’ pairs distribution throughout their relative velocity module exist. These functions are: G(ll) is the distribution function of pairs inside a light-light component, G(lh) the function of molecules’ pairs of light-heavy component and G(hh) is a function of molecules’ pair inside a heavy component. The numerical calculations of the corresponding “overlap” effect of bimodal distributions for pair of molecules was performed for a special case of small concentration values of heavy component in binary gas mixture (Rayleigh gas). It is known that in Rayleigh gas this effect for function G(hh) is most noticeable. While its computation, the molecules’ rotating degrees of freedom were accounted for. | ||
Minin N. V. The use of combined pulsating air breathing jet engine as a propulsion system for small-size unmanned aerial vehicles. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/f5f/Minin_rus.pdf In the report is considered the problem of creation and study of design of the new type of small-sized jet engine with free-piston membrane supercharger of a fuel mix in which the part is used for internal cooling heat-stressed mobile units of the engine and reception of work of compression of the compressor membrane type. The scheme of the new energy installation is developed. Thermal and thermodynamic calculations by technique of the authors are made. The basic constructive sizes of the engine are calculated and the problem of cooling of piston unit by the charge of a fuel mix of the engine that has led to partial regeneration of heat in a cycle to decrease in the specific charge of fuel and increase in altitude is solved. The maximum power of the power plant is limited by the working diameters of the piston group, its mass, frequency of operation. Examining the design parameters of the engine raises questions on the solution, for minimum capacities — the task of maximum piston operation speed at a speed of up to 30 m/s, a constructive and technological solution to the problem of avoiding traditional spring-ring sealing methods and switching to a smooth pair, Liquid wedge. And also complete withdrawal from the rotational movements of the crank drive, use in the atmospheric engines of the membrane compression system, with direct massless drive from the reciprocating motion of the lightweight piston group and the group of damper compression in the cycle. And the use of synchronizing mechanisms synchronization of moving pistons, cyclically operating without compression loads. Based on the developed methodology, the main parameters of the aircraft with a starting mass from 1 to 100 kg have been evaluated and it is shown that the proposed new variant of the combined remote control has a weight efficiency comparable with known developments and deserves further more thorough research. Based on the preliminary technical and economic analysis of the lightweight UAV, it is shown that the proposed version meets all the basic requirements of the current stage of development of launch vehicles. | ||
Lunev E. M., Neretin E. S., Budkov A. S. Development and study of aircraft trajectory control model while flying en-route of four-dimensional area navigation. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/82a/Lunev_Neretin_Budkov_rus.pdf This work is devoted to the analysis of the existing algorithms of trajectory control and their updating up to the level of 4-D area navigation (4D-RNAV) for further implementation while developing prospective automatic control systems for en-route flight. With the advent of satellite systems, navigation has changed qualitatively in the direction of increasing accuracy. However, navigation is only one of the constituent parts of the overall process of flight execution. It should be considered thereupon in general concept, namely, communication, navigation, surveying and organization of the air traffic, developed by ICAO in the 1980-s. The navigation concept of the future developed by ICAO is based on the area navigation. The area navigation principle allows an aircraft to execute a flight on any desired path and thus realize the advantages of navigation of higher accuracy in improving the structure of air area. It leads to simplifying of air traffic servicing, and foremost decrease of aircraft operating costs. The planned flight path can be specified not only in the horizontal plane in the form of a route, but also in the vertical plane, by specifying the flight heights of the waypoints, angles or gradients of the trajectory inclination. In addition, a space-time trajectory can be set, when for some points the time of their flyby is specified. In accordance with the dimension of the «space» in which the guidance is carried out, the area navigation is subdivided into three types: – 2D-RNAV ‒ two-dimensional RNAV in the horizontal plane — LNAV (Lateral Navigation). Sometimes, using a literal translation, it is called lateral navigation, since the guidance is provided only by lateral evasion; – 3D-RNAV ‒ three-dimensional RNAV in the horizontal and vertical planes. For navigation in the vertical plane, the abbreviation VNAV (Vertical Navigation) is used; – 4D-RNAV is a four-dimensional RNAV in the horizontal and vertical planes plus the solution of the problem of regulating the speed of flight for passing points of the route or arriving at the aerodrome at a given time. Zone navigation by time is abbreviated as TNAV (Time Navigation). [3] The problem of area navigation implementation consists not barely in ensuring the flight on an arbitrary path, but in ensuring its accuracy according to the requirement set in the given region. In modern aero Thus, the issues of area navigation were closely interleaved with RNP problems. They were so closely interleaved that these two ranges of issues were incorporated into a single ICAO document «RNP Manual» [1]. Today RNP is considered as a tool for flight technical and regulatory control with RNAV application. Depending on the strictness of requirements to the accuracy of the specified path following, and the type of functional requirements to onboard equipment the following notations are widely used: – B-RNAV (Basic RNAV) — the main (basic) area navigation; – P-RNAV (Precision RNAV) — precise area navigation; ‒ RNP-RNAV — area navigation with required navigation performance. RNAV is considered by ICAO as the main type of navigation of the future, since it has a number of undeniable advantages over conventional, traditional navigation. | ||
Sokolov S. V. The Integrable Case of Adler–van Moerbeke. Mechanical interpretation. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/f85/Sokolov_rus.pdf The Adler–van Moerbeke integrable case is considered. The case of integrability founded in 1986 by M. Adler and P. van Moerbeke is the most complicated in the rigid body dynamics. It came due to papers A.S. Mishchenko and A. T. Fomenko dedicated to integrability of Euler equations on finite-dimensional Lie groups. As a result a new family of integrable quadratic Hamiltonians with additional integrals of fourth degree on so(4) was appeared. The existence of quartic additional integral is connected with special symmetry so(4) admitting real representation as direct sum of two copies of so(3). Euler equations on Lie algebra so(4) also describe the motion of a rigid body with an ellipsoidal cavity filled by a perfect incompressible vortical fluid around a fixed point in a case of uniform fluid vorticity. These equations as a model of the Earth’s rotation were studied by V. A. Steklov. Modern results for integrable metrics on so(4) and their mechanical interpretation can be found in many reviews. After Poincare we consider rotations of rigid body with cavity, which contains inviscid incompressible liquid, about fixed axis. Such a case characterizes by additional integral of Lagrange type and corresponds to axially symmetric mass distribution. We give one of the possible mechanical interpretations for the integrable case under consideration. We explicitly present the most convenient form of additional integral. Put some partial relations between principal values of inertia tensor we reduce our system to Poincare case. Connections with some classical integrable mechanical problems are observed. Conditions of physical realizability for this mechanical model are discussed. | ||
Shchukin A. V., Khabibullin I. I., Il'inkov A. V., Takmovtsev V. V. The effect of diffuser dimple's shape on its flow-around pattern. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/eb6/SHCHukin-KHabibullin_Ilinkov_Takmovtsev_rus.pdf This experimental study is aimed at the searching an easy-to-manufacture shape of the previously submitted by the authors highly efficient surface thermal exchange intensifier of a separation type with high functioning intensity of large-scale vortex structures, namely two-cavity diffuser dimple. This dimple, placed in an array of dimples demonstrated a higher level of heat dissipation, exceeding more than three times the heat dissipation while a smooth plate flow-around. It was accepted as reference. The high level of thermal effectiveness of this dimple is associated with implementation of optimal relative height of the rib separating its hollows, the diffuser shape of its hollows for the backflow, as well as with their slope in plan view of the relative direction of the main flow. Based on visualization of the flows and determination of the pressure coefficient C_{p} in the bottom part of the studied dimple’s variants the experimental data was obtained on its shape in terms of the self-organizing large-scale vortex structures. The ways of geometric shape of the two-hollow diffuser dimples’ simplifying were studied, and, hence, its manufacturing technology under condition of preserving the intensity and continuity of large-scale vortex structures functioning. The authors established that without the hollows’ separating rib, when the entry edge is described by the line of radial contour, two-hollow dimple passes into the class of one-hollow dimples with permanently functioning single large-scale vortex structure. The rarefaction level, however, in the in the dimple’s epicenter decreases compared to the two-hollow diffuser dimples. The performed comparative studies revealed the existence of the rational geometry of one-hollow diffusor dimple of a separation type ensuring permanent functioning of vortex structures. This dimple allows much simpler manufacturing technology compared to the two-hollow diffuser dimples. However, it is inferior to the latter in the intensity of large-scale vortex structures. Thus, following the two-hollow diffuser dimple structure it is necessary to explore and find such installation angle relative to the main flow that provides maximum vortex intensity. This is essentially the algorithm for further optimization of the easy-to-manufacture one-hollow diffuser dimple of separation-type studied here. | ||
Pozhalostin A. A., Goncharov D. A. On axisymmetric parametric oscillations of a fluid in a cylindrical vessel. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/1a1/Pozhalostin_Goncharov_rus.pdf The authors considered the case of axisymmetric parametric oscillations of an ideal fluid filling the cylindrical vessel. They obtained the differential equation of parametric oscillation damping with account for the main parametric resonance, as well as numerical values of the variables comprising this equation. It was shown that could initiate small oscillations of the system, with the corresponding values of the modulation index. The value of the modulation index is determined by Van der Pol method. The problem was considered in the linear formulation, with fluid movements were assumed small. The velocity potential satisfies the Laplace equation in a cylindrical domain. On the wetted surface of the vessel the conditions of impermeability were met, while on the free surface of the liquid the linearized boundary condition was met. The velocity potential, in accordance with the Fourier method, was represented as a series of the hyperbolic functions, Bessel functions of 1^{st} order and the time factor. The equation for the parametric oscillation was obtained for the time factor from the equation for the velocity potential. The kinetic energy of the mechanical system was determined by the gradient of the velocity potential. The reduced inertia coefficient of the system was calculated by the Green’s function method. The viscous resistance force in the fluid was assumed proportional to the first degree of speed. The fluid velocity was defined as the gradient of the velocity potential. Then we compose the Rayleigh dissipative function. Expression for the potential energy was composed. We composed the Lagrange equation of the II-nd order with account for the dissipative forces, due to the presence of viscous friction in the mechanical system under consideration. The resulting differential equation is a second order differential equation with a small parameter. The damping coefficient implies experimental determination. We indicate references to the papers, which present the numerical values of the damping coefficient. Further, the damping coefficient was assumed as known. The averaging was performed, and the border region of parametric resonance instability was sett. The conclusion on the existence of the small oscillations of the respective values of the modulation index was made. | ||
Kuli-zade M. E., Skorokhod E. P. Development of kinetic models of the moving plasma. The constants of the radiative d-p transitions of the xenon ion. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/2f7/Kuli_Zade_Skorokhod_rus.pdf Multi-level physicochemical kinetics at present remains relevant to General theoretical issues of spectroscopy of low temperature plasmas and optical diagnostics in the framework of radiation plasmodynamics, in particular for the device-specific debug modes, where “working fluid” is the Xenon plasma. When composing kinetic equations, multiple radiation constants (Einstein coefficients) are necessary. Selection of the model itself is predetermined by considering the xenon ion level scheme, recorded in LS-relations. The level scheme composed and supplemented by the quantum-defect approximation allows calculate the transitions that are absent in the reference edition [12]. Six models of probabilities' calculations including the radiation transitions 5d ‒ 6p relating to the lowermost levels are considered. The radial integrals required for calculations of A_{ki }/10^{6} transition probabilities were calculated by the the Bates–Damgaard method using two different values of the effective quantum number: a specific level, and for the entire configuration as a whole. They were also calculated according to the of Hartree–Fock–Slater method. Angular dependencies for these three methods were performed in approximation of the LS–relation and in the framework of intermediate relation. The article presents the results of the above-mentioned six quantum-mechanical models for 5d ‒ 6p 314 dipole transitions. A comparison with experimentally obtained results of other authors was made [18–21, 24, 16]. The reference data includes also the values of the photo-transition probabilities obtained from the experimental data on the line shifts corresponding to the quadratic Stark effect [22]. The Einstein coefficients differ within a few orders of magnitude. Thus, for the transition 6p^{ 4}P_{5/2 }→ 5d ^{4}D_{7/2} with the wavelength of 605.115 nm, the probability calculated by him in Bates‒Damgaard approximation with the use of a relation gives the value of A_{ki }/10^{6} = 0.48 with account for the intermediate relation of 1.5; according to the Hartree-Fock-Sleter method in the framework of the intermediate link ─ 0.041. The other authors give: 20.5 ─ [19]; 52. ─ [20]; 21. ─ [16]. The value obtained from experimental data on the lines' shifts corresponding to the quadratic Stark effect [22] is A_{ki }/10^{6} = 52.9. The presented Einstein coefficients calculations results from the 5d levels supplement the reference data of the 6s ‒ 6p photo-transitions probabilities [15]. | ||
Blagodyreva O. V. Ritz and finite element methods application to aeroelastic vibrations computation of a cruise missile . Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/660/Blagodyreva_rus_2_1_1.pdf The article studies the aeroelastic stability of a cruise missile performing longitudinal short-period motion in incompressible airflow. The missile is modeled using a beam structure, including the fuselage, two straight outer wings and flight control surfaces — elevators. The wing of the missile is considered as an elastic beam operating in bending with transverse shear and torsion, while the fuselage and the control surfaces of the missile are considered as rigid. It is assumed, that the elastic vibrations of the wing panels occur according to the hypothesis of flat sections. Control drives with wiring are considered disconnected, and their effect on the structure is replaced with the unknown control forces. Aerodynamic loads are determined based on the quasi-stationary theory of plane-parallel flow cross sections of the wing. The longitudinal compression of the missile body under the effect of thrust force of an engine is also accounted for. The equations of small vibrations of the system are represented in the form of Lagrange equations of the second kind in generalized coordinates. The generalized coordinates are considered as normal coordinates, representing the movement over the eigenvibration mode of a free structure with fixed operating controls. Based on the Ritz method the unknown functions of transverse displacements of the axis of the fuselage, the transverse displacements of the axis of the wing and the angle of twist of the wing are presented in the form of expansions along the generalized coordinates. For a more accurate study of the behavior of a wing’s flexural-torsional oscillations the finite element method (FEM) was used. The wing is separated into a number of compartments — finite elements (FE), within each the geometrical, stiffness and mass properties are assumed to be average and constant. The article presents a comparative calculation of the flutter of an elastic missile using the Ritz method and the finite element method (FEM). The graphs of the variation of natural frequencies of the missile depending on the changes of the flight speed and engine thrust power are plotted. The critical speed and the stability region of the missile were defined respectively for each method. All the calculations were performed with the software “Wolfram Mathematica 8”. | ||
Gnezdilov V. A., Grishanina T. V., Nagornov A. Y. Deformation of a plane statically indeterminate frame system with buckling bars. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/c05/Gnezdilov_Grishanina_Nagornov_rus.pdf Long frameworks (lattice beams) are often used in different building structures (cranes, masts, bridges, pylons of electric air-lines, etc.), as well as in space structures deployed or assembled on orbit. In some cases such structures can undergo to large elastic displacements with large angles of the bar turns. At the design it is usually required that there must not be any irreversible deformations and damages (cracks) in the structure at the maximum operational loads. Statically indeterminate frames allow elastic buckling of some compressed bars with moderate finite deflections limited by the relative longitudinal displacements (contaction) and the turn angles at the joints which connect the buckled bars with the others. In this work the new approach is developed for solution of geometrically nonlinear problem of deformation for a plane frame system with large displacements and turn angles taking into account buckling of some bars with moderate elastic deflection. Every bar of the system rigidly connected in the movable joints with the other bars and subjected to tension or compression and bending in considered as a beam finite element. Large displacements and turns of bar in the structure are described by four unknown coordinates of the bar ends (the joints it connects) and by three supplementary generalized coordinates. Two of them represent the relative turn angles of the bar ends and the third — its deflection due to moderate elastic bending. Such representation of describes sufficiently exactly the possible instability of the bar with moderate buckling deflection. The nonlinear equilibrium equations in displacements for the system loaded by the forces and moments applied in the joints are obtained by use of the virtual work principle. These equations are solved numerically. The example of calculation of the system behavior subjected to the increasing load with the successive buckling of some compressed bars is considered. | ||
Garipova L. I., Batrakov A. S., Kusyumov A. N. Accounting for dynamic conditions of aerofoil flow-around while solving the problem of a helicopter main rotor trimming angles determining. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/cdc/Garipova_Batrakov_Kasyumov_rus.pdf The main rotor trimming is one of the important tasks of helicopter aerodynamics. The aim of trimming consists in determining the values of balancing angles (total and cyclic pitch angles) of the main rotor, which allows minimize longitudinal and lateral moments, as well as vibration load. A simple approach to the main rotor's balancing angles determination is based on the Blade Element Momentum Theory (BEMT), based on steady-state aerofoil aerodynamics. However, while straight and level flight the helicopter's blade sections motion bears a complex oscillated character. For this reason, aerofoil performances can differ significantly from its steady-state equivalents. The aim of this research is numerical simulation of the oscillating NACA 23012 aerofoil flow-around to study the effect of dynamic flow conditions corresponding to a forward flight mode on the values of the main rotor trimming (total and cyclic pitch) angles. Numerical simulation was performed using HMB code (Liverpool and Glasgow universities) based on the Unsteady Reynolds averaged Navier–Stokes equations (URANS) with k‒ω SST turbulence model. The results of study revealed that the dynamic condition leads to significant changes of the aerofoil aerodynamic characteristics and the main rotor trimming angles compared to the steady state formulation. Based on these results a correction can be employed to improve the simple BEMT approach accuracy. | ||
Klyagin V. A., Petrov I. A., Shkurin M. V. Analysis of avionics' blocks placement on the aircraft of various types. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/3b9/Klyagin_Petrov_SHkurin_rus.pdf Avionics’ layout on a modern aircraft is a complex engineering task. A quality solution to this problem currently became potentially possible by using PC. However, at this moment, existing application programs are based on heuristic methods [1, 6, 7] or on analytical solution [4, 5] of the problem. They are still not widely used. One reason for this is the lack of information about the patterns of avionics’ distribution. Statistical analysis will highlight patterns that will become the basis of new methodology. Statistics will clarify the existing methods as well. The first necessary step for the analysis -is gathering information on the layout diagrams of aircrafts in context of avionics’ placement. Combat aircraft of the second half of the twentieth century were studied. The most common source was the photos of real aircraft, showing the avionics (e. g. open avionics bays). Next step consisted in calculating the total number of items of avionics with the differentiation of the installation type. This work assumes the following types of installation:
Thus, the article presents the analysis of the avionics’ placement on combat aircraft of the second half of the XX century according to the installation type for the various classes and the date of the first flight. The results show that for all classes of the aircraft, the vast number of blocks were arranged on the shelves. Single mounted makes approximately 9.5% of the components. Only two out of the 35 types dominated by point installation. Also seen a number of patterns such as on devices with smaller dimension is slightly higher relative number of blocks with a single installation. Based on the work a conclusion was made that for the automated layout method development it is useful to represent the location of the avionics in the planes. | ||
Ngo Q. T., Solenaya O. Y., Ronzhin A. L. Analysis of mobile robotic platforms used to batteries service of unmanned aerial vehicles in autonomous missions. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/304/Ngo_Solenaya_Ronzhin_rus.pdf The problem of increasing the operating time of unmanned aerial vehicles in autonomous missions is considered. Approaches to charge or replace on-board batteries on the accompanying robotic platform are analyzed. The key issues remain questions of the autonomous landing of the unmanned aerial vehicle on the platform and the way of servicing battery. The available prototypes of service robotic platforms are differed in the complexity of internal mechanisms, speed of service, algorithms of joint operation of the platform and unmanned aerial vehicle during the landing and maintenance of the battery. Autonomous landing of aerial vehicle in modern studies is considered not only on a fixed platform, but also on a mobile platform that moves in various environments. Landing unmanned aerial vehicle on a service charging station is realized with the help of various systems of navigation and analysis of the surrounding area. A battery-replacement system significantly reduces the preparation time of a multi-copter for a new flight and increases the total number of multicopters that are simultaneously in an autonomous mission. The charging system has a lower cost compared to the battery replacement system by minimizing the mechanical components of the structure. Modern means of navigation and technical vision ensure the landing of UAVs on the ground robotic platform can be performed with high accuracy in indoor environments. In outdoor application, taking into account the influence of weather conditions, the landing error is much higher. To communication the mobile platform to unmanned aerial vehicles, wireless means are mainly used to ensure their coordinated work during landing and take-off, and also to control several vehicles in the queue for charging. The purpose of this study is to develop a multifunctional mechanism for connecting a multi-copter to a ground-based robotic platform that performs the functions of their transportation and maintenance. Based on the results of the analysis, a classification of existing systems installed on robotic platforms for the maintenance of batteries is made. A further study will be devoted to the development of the requirements for the design of a multicopter maintenance system on a projected ground platform, taking into account its functional purpose, as well as the creation of software and hardware for the joint operation of multicopters and a platform. | ||
Rebrov S. G., Golubev V. A., Golikov A. N. Laser ignition of oxygen-kerosene fuel in rocket technique: from igniters to rocket engines . Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/030/Rebrov_Golubev_Golikov_rus.pdf The article reviews the main results of research aimed at introducing laser ignition for rocket engines using oxygen-kerosene fuel. The purpose of the work was to determine the operational parameters of the laser ignition system and the ranges of the composition and fuel rate of the fuel mixture to ensure reliable ignition in igniters, rocket thrusters and sustainer rocket engines. The method of initiating a spark of optical breakdown in area with favorable ignition characteristics of the mixture was used as a method of ignition. The laser radiation was focused either in the volume of the mixture or near the metallic surface for that. The tests covered a wide range of changes in the operating parameters of both combustion chambers and ignition systems. Laser ignition was successfully tested on chambers, starting from a small volume of several cm^{3} for igniters and low-thrust engines to the sustainer chamber of the engines of the first, second stages of the Soyuz launch vehicle with a volume of 65 dm^{3}. The tests were carried out using mixtures of both a reducing composition at a value of oxidizer-to-fuel ratio to 0.1 and an oxidizing composition with a value of oxidizer-to-fuel ratio up to 11. Laser parameters were also ranged for output pulse energy from 1 mJ to 100 mJ and for pulse repetition frequency from 10 Hz to 100 Hz. The complex of carried out works made it possible to develop the technology of laser ignition of oxygen-kerosene fuel with the determination of the necessary operating parameters of fuel mixtures and the ignition system itself with regard to rocket technology: igniters, thrusters, large combustion chambers for rocket engines with thrust up to 18 tf. Guidelines for introduction of laser ignition for large size rocket engine combustion chambers have been developed on the basis of experience gained. It was also shown the feasibility of laser ignition of large-sized oxygen-kerosene chambers using small-sized lasers mounted directly to the combustion chamber. These results allowed to propose a scheme of laser ignition system to replace the existing pyrotechnic for the first and second stages of the Soyuz launch vehicle, based on the use of micro lasers with fiber radiation delivered to them from a reusable stationary diode pumping station placed on the launch site. | ||
Dolgushev V. G., Ionov V. A., Kun N. V., Matveenko A. M. Development trends of modern aircraft onboard hydraulic systems. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/fdc/Dolgushev_Ionov_Kun_Matveenko_rus.pdf Resiliency is essential for operation of an aircraft during its lifetime. In modern aircraft hydraulic system a specified level of fail-safety in the design process is ensured by the initial selection of the structure and parameters of the system, which cannot be changed during the flight. The fail-safety can be improved by increasing various safety factors and redundancy of elements. Nevertheless, in its turn, it leads to the system weight increase. However, the increase of fail-safety without weight increase is possible through adjustment of internal parameters by changing operation modes (e.g., unloading in cruising flight and the crossing of the settings at high loads or failure in the system). The decisive factor is the smaller weight of the system, giving the opportunity to increase the combat effectiveness of the aircraft either due to the smaller mass and therefore greater maneuverability, or to the larger mass of ammunition. For large passenger aircraft, using forced modes to compensate for failures of pipelines, implementation of titanium alloys and high rated pressure level will allow create a hydraulic system with a significantly smaller mass. A mixed system, incorporating centralized hydraulic system and stand-alone drives is expedient to be applied on the military-transport aircraft, which due to the extra mass is possible to achieve high survivability. | ||
Borisov A. E., Leont'ev V. A., Novak V. N. Analysis of the features of the main rotor with negative offset of the flapping hinge. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/db6/Borisov_Leontev_Novak_rus.pdf In this paper a new concept of a high-speed main rotor of a single-rotor helicopter is considered. A new concept of a high-speed main rotor is to use the design rotor hub, which allowing to obtain a natural frequency of flap motion blade lower than the rotational speed of the rotor. Reduction of the natural frequency, as well as its increase (screws with positive flapping-hinge offset or rotors with elastic fastening of blades) leads to a phase shift of the flapping motion of the blades. The phase shift of the blades flapping motion leads to an increase the angles of attack on the advancing side of rotor and to a decrease in the retreating side, and thereby detracts from the appearance of a stall at high flight speeds. The analysis of the effect of its design features on aerodynamic characteristics is carried out. Presented are the equations of the flapping motion of main rotor blades with negative offset of flapping hinges, as well as of the moment on the rotor hub. The paper also considers the method for calculating the coefficients of the first harmonic of the blade flapping motion and the expressions for calculating angles of attack in blade sections. The analysis of the operation of rotors with both negative and positive flapping-hinge offset is carried out, an estimation of the influence of some rotor parameters on angles of attack of blade sections is obtained. Also presented are the results of calculating such rotors that illustrate the possibility of increasing angles of attack on advancing blades and reducing them on retreating blades by means of the swash plate deflection. | ||
Afanas'ev V. A., Monakhova V. P., Muhina S. D., Versin A. A., Nazyrova O. R., Bolkhovitin M. S. Experimental means development for pressure receivers' calibration. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/e29/Afanasev_Monakhova_Mukhina_Versin_Nazyrova_Bolkhovitin_rus.pdf The article presents the results of the structural components' development of the experimental workbench for calibration of receivers of total and static pressures in the jet of a gas flow. The speed range of the controlled gas flow at the subsonic nozzle edge is regulated from λ_{с} = 0.3 to λ_{с} = 1.0. The necessity of this workbench development is associated with the fact, that pressure receivers' designs are developed individually for various placement locations along the path of the gas turbine engine compressor. The basic requirements that had to be met while the development of the stand are as follows – The relative velocity of the gas stream λ in the placement of the receiving holes of the comb should be measured with an accuracy of ±0,01; – The numerical values of the pressures in the pneumatic circuits of the comb should be stay within ± 0,3% of measured values; – The linear and angular positioning parameters of the receiving holes of the comb under study should be determined with an accuracy of ±1 mm and ±0.5 degrees respectively. The following calculations were performed in this work: – Calculation of the subsonic nozzle profile; – Design of the diffuser. Calculation of the subsonic nozzle profile allows obtaining a controlled airflow at the outlet with a uniform velocity value in the cutoff of the nozzle. The pointing device allowing the smooth movement of the inlet orifice of the studied receiver with the possibility of speed adjustment, and position it on the geometric axis of the nozzle, as well as change the angle between the flow velocity vector and the axis of the inlet orifice within the limits of ± 45° in the tangential and meridian planes. The article also presents a calculation of the diffuser design meant for for converting the kinetic energy of the flow into static pressure. | ||
Konstantinov M. S., Min T. . Optimization of the trajectory of launching the spacecraft into the geostationary orbit for transport system with specific impulse of the engine 600-900 s. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/964/Konstantinov_Min-Teyn_rus_.pdf The spacecraft flight from the low Earth orbit to the geostationary orbit is considered as a typical transport operation. The optimization of the interorbital flight, the control laws for the movement of the spacecraft during the flight and the flight trajectory are carried out. The main goal of the work is to provide the users who analyze the interorbital flight, the possibility of correct and simple estimation of the characteristic velocity for the transport operation in question. When optimizing the flight from the low Earth orbit to the geostationary orbit, a method based on the Pontryagin maximum principle is used. The problem of optimizing the trajectory reduces to the boundary-value problem. The boundary-value problem is solved using the evolutionary strategy with the adaptation of the covariance matrix. The characteristic velocity for the operation is considered as a function of the specific impulse of the engine and the initial reactive acceleration. Specific impulse of the engine is considered in the range of 600-900 s. The initial reactive acceleration is considered in the range 1.25-12.5 mm / s^{2}. The results of the analysis are presented in the tables form of the characteristic velocity reactive as the function of initial reactive acceleration (the range 1.25-12.5 mm/s is considered) and the specific impulse (range 600-900 s). Such a range is typical, for example, a solar thermal rocket engine. Another result of the work is the analysis of the optimal flight, the analysis of the properties of the optimal flight and the optimal control law for the movement of the spacecraft during the interorbital flight. The results of the work can be used to analyze the space transport systems for interorbital spacecraft flight with the specific impulse of the engine in the range of 600-900 s. The characteristics of the optimal flight scheme are analyzed. The optimal flight path contains three characteristic sections. On the first of them, the SC engine operates at the perigee section of the multi-revolutions trajectory. In this area, the eccentricity of the orbit increases (the radius of the apogee increases, with a slight increase in the perigee altitude). The inclination of the orbit decreases a little due to a small yaw angle (less than 2 degrees). At the end of the first segment of the flight path, the radius of apogee appears to be substantially larger than the radius of the geostationary orbit. On the second part of the trajectory, the engine operates at the apogee sections of the trajectory. In this case, the radius of the perigee of the trajectory increases actively, the radius of apogee hardly increases. The yaw angle on the flight path provides an effective reduction in the inclination of the orbit. At the beginning of the section, the yaw angle value is large, the optimal yaw angle decreases in each revolution. At the end of the second section of the trajectory, the inclination of the orbit is practically zero. On the third part of the flight path (the duration of the section is approximately two revolutions of the trajectory) the active sections are located in the vicinity of the perigee of the orbit. The engine breaks the spacecraft, providing zero eccentricity of the final orbit. | ||
Sypalo K. I., Medvedskiy A. L., Babichev O. V., Kazarinov G. G., Kan A. V. Engineering of Aircraft Demonstrator. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/6fa/Sypalo_Medvedskiy_Babichev_Kazarinov_Kan_rus.pdf The article presents the methodology for creating demonstrators of technologies in aircraft building, based on the harmonization and use of the existing system of national standards. As one of the mechanisms of realization of a control system of research works, it is supposed to use a scale of assessment of technology readiness level. The technology readiness level scale is taken as a basis for gradation of development stages of new technologies by many departments and the organizations, both in the USA, and in some other countries. The classification used reflects a condition of research programs depending on the current technologies readiness level that simplifies control for developers and customers control over the course of research works and the choice of the technologies, most ready for industrial introduction. The scale of technology readiness level represents the formalized assessment of degree of the technologies maturity for practical use when developing from the idea to a prototype of the complete system tested in the conditions close to real. On the grounds of the system engineering tools which are based on the formalization of measurements of technologies readiness levels, and use of the existing national standards base — state standard specifications — the methodology of creation the technologies demonstrators of technologies in aircraft industry has been offered. The presented methodology of creation of technologies demonstrators in aircraft industry solves a problem of integration of the existing system of national standards with the world practice of quantitative and quality standard of the developed technologies. Harmonization of standards on carrying out research and development with world practice and also use of quantitative and high-quality indicators of technology readiness level scale, including methodology for creating of aircraft technology demonstrators, will allow to reduce significantly risks during creation of the aircraft equipment. | ||
Kotel'nikov V. A., Kotelnikov M. V., Filippov G. S. The role of guard electrodes in probe diagnostics. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/887/Kotelnikov_Kotelnikov_Filippov_rus.pdf Flat remote and near-wall probes are widely used in probe diagnostics of rarefied plasma (static and dynamic). They are installed on hypersonic aircraft and space satellites in order to study the radiophysical parameters near their surface. Flat probes can be installed both parallel and perpendicular to the flow velocity in the rarefied plasma streams. Nonlinear border and edge effects occur at the edges of a flat probe, which have a significant influence on the probe current. The boundary effect is associated with the thickening of the lines of force of the electric field at the boundary of the active surface of the probe. The final effect arises under the influence of a directed flow velocity if the probe is oriented parallel to the flow velocity. Charged particles enter the space charge layer of the probe. They can fly through the probe line and not contribute to the probe current, depending on the potential of the probe and the velocity of the plasma flow. The present article is devoted to an analysis of the effect of these nonlinear effects on the probe current. In the literature, there is insufficient information on this issue, the technique for conducting a probe experiment, and processing probe characteristics, taking into account the border and edge effects. The physical and mathematical models of the problem are formulated. Extensive computational experiments were carried out. Conclusions and recommendations useful for the practice of probe measurements are made. Consider a probe in the form of an elongated strip of width 2r_{р} and potential φ_{ρ}. The directional plasma flow rate U_{∞} is parallel to the probe surface and perpendicular to its short side (fig. 1).
a) the probe is oriented along the flow,
b) the probe is oriented towards the flow;
1 - probe surface,
2, 3 - the surface of the guard electrodes.
If the characteristic size of the probe is 2r_{р}≥10^{3}r_{d}, (r_{d }is the Debye radius), then the effect of the border and edge effects can be neglected and the Bohm formula can be used when processing probe characteristics. If 2r_{р}<10^{3}r_{d}, then the arising nonlinear effects can be removed by constructing the guard electrodes in the form of strips along the elongated sides of the probe, separating them from the probe by thin insulating layers. In this case, the Bohm formula is also used. The width of the guard electrodes is calculated in numerical experiments and is presented in the work in the form of graphical dependences U_{∞}, r_{p}_{ }and the potential φ_{ρ} (fig. 2, 3). If the probe in the form of a strip is directed by its active surface towards the flow, the border effects is absent, and the edge effect is analogous to the case of parallel flow around the probe. If 2r_{р}≥10^{3}r_{d}, then the Langmuir formula, which describes the ion current with concentration, flow velocity and probe potential, is valid. If 2r_{р}<10^{3}r_{d}, then guard electrodes are placed, which remove the effect of edge effects. Their size is much smaller than with parallel flow around the probe. Recommendations for choosing the width of guard electrodes are given in the work as a function of the characteristic parameters of the problem.
If flat probes of another geometry (square, disk, etc.) are used, it is recommended to take their characteristic size 2r_{р}>10^{3}r_{d}. In this case, the role of border and edge effects is small and one can use the recommendations stated above for probes in the form of an elongated rectangle. | ||
Vernigora L. V., Pichkhadze К. М., Sysoev V. K. Analysis of optical beacon emitter parameters for spacecraft navigation system. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/fe2/Vernigora_Pichkhadze_Sysoev_rus.pdf Spacecraft (SC) optical observation is one of the main method of SC tracking and measurement of their parameters. The successful development of semiconductor emitters' technology allowed gaining the high-efficient laser diodes with high capacity level at low mass and dimensions parameters. This permits to develop optical beacon systems for spacecraft navigation based on these diodes. Firstly, these are optical beacons installed on planetary landing stations, such as Luna-Glob/Luna-Resource-1 (and in the future – on modules descending to the Martian surface). Installation of such beacons allows high-accuracy location of the landing stations with the help of spacecraft optical TV equipment and ground-based tracking stations. Being connected to the radioisotope power source they can be used as beacons for future lunar missions. The article describes the developed algorithm for semiconductor light sources' selection necessary to solve the problem of optical beacons design for space expeditions: 1. The beacon's radiation should be reliably registered by the receiving optical system. This requires the following steps: ‒ Determination of the necessary emission power. Selection of the emitter's power is stipulated by sensitivity of the receiving ground-based optical system, distance to the spacecraft, the light source radiation angle and, of course, the time of exposure; ‒ Selection of the semiconductor light source allowing creation of low divergent light beams, which is necessary for transmission of this radiation for long distances; ‒ Determination of necessary emission spectrum of the semiconductor light source (rather wide emission spectrum of the semiconductor light source is allowed for “space-to-space” system). In the case of “Spacecraft‒Earth” system selection of emission spectrum is stipulated by the atmosphere's properties; ‒ Time persistence of the optical beacon should not exceed the frequency response of the receiving equipment, necessary for signal coding. 2. Optical beacon should provide operation in the space flight conditions: diminutive mass and dimension parameters, long lifetime, radiation and vibration resistance, capability to operate at low voltage, high efficiency. The results of the analysis were used for selection of the optical laser beacon emitters developed within the framework of Luna-Glob and Luna-Resource-1 projects. | ||
Zakovryashin A. I. Construction of membership functions of radio-electronic equipment parameters on experimental data. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/48e/Zakovryashin_rus.pdf
Estimation of a radio-electronic equipment object’s workability supposes its diagnosis. | ||
Kulikov S. V., Gudaev R. A., Mikhalchenkov A. A., Zelenkov A. V., Vikulova Y. M. Methodology of synthesis of ultrahigh frequency matching units on nonhomogeneous loops. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/dfc/Kulikov_Gudaev_Mikhalchenkov_Zelenkov_Vikulova_rus.pdf The goal of the article consists in improving the methodology of broadband matching units’ synthesis for complex loads, allowing ensure maximum of match strips spacing by employing nonhomogeneous stepped loops. The set goal is achieved based on Kohn method allowing compute broadband matching units for complex loads on nonhomogeneous loops. The versatility of the suggested method consists in the fact that instead this method any other method, allowing compute a matching unit on homogeneous loops can be used. This work was supported by the Grant of the President of Russian Federation. Based on the obtained results of studying of characteristics of the broadband matching unit on nonhomogeneous loops performed using mathematical model the following inferences can be drawn: Increasing of relative match strip width ω leads to damping reduction in a stop band. Reducing the standing wave ratio in the match strip К_{СТ} leads to a decrease in attenuation in the stop band. Increasing the number of loops of the matching unit contributes to the increase i in the stop band. When placing a heterogeneous loop near the source, the attenuation in odd tuple bands increases, and in even tuple bans decreases. The match strip relative width increase w, stand wave ration in match strip reduction and increasing the number of loops of a broadband matching unit affects the value of match strips’ spacing, which is expressed in its reduction. Employing the five-step loops can significantly improve the characteristics of band rejection, but the characteristics in match strip are degrading. The simulation results of the synthesized broadband matching unit on nonhomogeneous loops confirmed the principal possibility of developing physically realizable impedance matching units with an increased spacing of the parasitic match strips. | ||
Rybnikov S. I., Nguyen T. S. Analytical design of damping system for flexural aeroelastic vibrations of the wings of airliner. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/40e/Rybnikov_Nguen-Tkhan-SHon_rus.pdf The analytical design of the active system of damping of flexural aeroelastic oscillations of the wing, which is optimal according to the extended variational criterion of generalized work. The first tone of aeroelastic oscillations of wing airliner often have frequencies of the same order with the natural frequency of undamped oscillations of the steering gear. Therefore, the synthesis and analysis of the dynamics of the stabilization systems of the airliner dynamics such the angular position of the wing is expedient to take into account and to ensure high quality in these adjustment systems may be required to build the system damping vibrations of aeroelastic wing independent or internal in relation to systems organized on the basis of the aileron channels. The assumption of the symmetry of the oscillations of the wing considered the synthesis of active system of damping of flexural vibrations of a wing of the airliner. For the synthesis of the damping system uses the method of analytical design of optimal regulators (AKOR) according to the criterion of the generalized work, the extended variable energy members of the penalty function, which takes into account the work of the control forces to move the controlled object. The joint variation in energy of the members of the penalty function is intended for counter control the level of damping wing in the transitional processes of the system, on the one hand, control-related energy consumption. Damping of flexural vibrations of the wing is constructed using as the executive bodies of external ailerons, or specially imposed limit deflected surfaces mounted on the wing. Steering was adopted with a minor, about 15% excess frequency undamped oscillations over the frequency of the third tone aeroelastic oscillations of the wing that allows you to build a complicated damping system oscillations, which includes the first and third tones. In the mathematical model of the damping system first and the third tone of Flexural vibrations of a semi-wing and working steering aileron are described by differential equations of the second order. The control is constructed as linear, in variants with complete information about the control object and with incomplete information containing signals only of the total velocities and displacements of the console. Performed parametric synthesis of the system damping with the current settings of the extended control object, it is shown that the choice of coefficients criterion, if sufficient control actions, it is possible to reduce vibration of the object, providing an unambiguous or even its monotonous transition function with its adjustable duration. The change in the coefficient k_{m} for the energy the members of the penalty function in the process of designing the system is an effective impact on the nature of the transition process in it. With its growth, the absolute values of the feedback coefficients in the system, its natural frequencies, the level and efficiency of the control action decrease, and the transient process in the system approximates to free fluctuations of the object. With decreasing k_{m}, conversely, the moduli of the feedback coefficients in the system and its natural frequencies increase, as well as the values of the control actions and their efficiency, the oscillation of the transient process decreases, then the process becomes single-valued and then goes monotonous. Tightening restrictions on the derivatives of the deviations from the ends of the console from a stable state to be performed in the form of an increase in the coefficients in front of them, with sufficient energy, leads to a decrease in variability transients in the system, in extreme cases , to its complete elimination . The handling qualities transients change in the coefficient k_{m} is maintained. | ||
Smirnov K. K. Automation of operations of traceability of integrated structures quality in the manufacture of VLSIs. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/bda/Smirnov_rus.pdf
Nowadays the quality of modern integrated circuits is considered as a complex indicator, which depends on production operations metrology support and improvement of technological process. The modern development of microelectronics with wide miniaturization solutions complicates control technology, measuring and testing of VLSI integration. Moreover, it requires constant improvement of the technological way of manufacture, technological solutions in the design of the production tools, creation of new instruments of monitoring and evaluation parameters, as well as the tightening of the shop rates and the transition to higher levels of automation of production processes. | ||
Astapov V. Y., Khoroshko L. L., Jozdani M. S., Khoroshko A. L. Manufacturing of Sheet-Metal Edge Formers of Aircraft Access Doors by Magnetic Pulse Method and Simulation Using CAD System. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/075/Astapov_KHoroshko_Dzhozdani_KHoroshko_rus.pdf When designing any components of various aircrafts, it is important that the designer knows the technical capabilities of the preforming and forging production, and focuses on the most advanced technology processes of their manufacture. A large number of components used in an airplane design are composed of parts made of sheet materials, which are used as edge formers. The presence of a web, edging and various elements increasing the stiffness and reducing the weight, is common for such parts. These sheet-metal parts present intricate and mainly closed forms, the manufacturing of which by methods of the plastic deforming requires rather complicated forging outfit and their finishing to the required dimensions following the deforming. The article is concerned with a topical issue of the determination of optimal conditions of exposure to the deforming force required in the prove-out of an intricate shape forming process of edge former structures by deforming a sheet-metal workpiece with the pulsed magnet field pressure, and the simulation of this process. The process of the magnetic pulse forming makes it possible to concentrate the exposure, deforming a sheet-metal workpiece, within the range of pre-set parameters and within a specified zone, but requires a thorough adjustment of technical regimes. Recommendations are developed for the determination of the required power parameters of the sheet-metal workpiece forming process ensuring the maximum efficiency of the process that reduces the number of technological operations, the complexity and the time of manufacture of the outfit and the equipment operation. In the theoretical solution, the improved mathematical models of the magnetic pulse deforming of the sheet material were developed with account of actual mechanical characteristics of the workpiece materials. The theoretical dependences obtained were experimentally tested on samples; the assumptions and assertions made were verified. The impact of the magnetic pulse deforming on certain properties of sheet-metal part materials was determined. The proposed new technical solutions for implementing the processes developed in practice were examined. Methods for experimental testing of the high-speed magnetic pulse forming of sheet material were developed and implemented using various moulds of complex geometric surfaces, including the material shift dynamics and the impact of the deforming on the metal characteristics, as well as special aspects of the forming and influence patterns of power parameters, processing factors and tool configuration in operation of magnetic pulse sheet-metal forming were established. The influence of the magnetic pulse deforming on mechanical and process characteristics of materials after their exposure to the pulsed magnet field pressure and forming in a mould was determined. It is found out that when applying the pulsed force action, the metal is compacted, its surface hardness is increased, and micro-fractures and porosity are eliminated, that is the quality of a metal zone deformed by the pulsed magnet field is improved. ANSYS LS-DYNA program, a multipurpose software-based multi-function system of a finite-element complex, was used for the computational investigation and simulation of the magnetic pulse forming process of edge former surfaces. When solving the problems by CAD system, the geometrics of workpieces, material specifications, and energy parameters of the magnetic pulse deforming were variated. The workpiece shift and its deformation in moulds having different profile shapes were simulated. Based on the solutions obtained and in comparison with scales of equivalents, it is possible to determine any timing-wise shift of the sheet-metal workpiece web, the final finite deformation of workpieces, any stresses arising in contact zones with forming tools during the deforming and forming. | ||
Efimov A. I., Il'in V. N. Methodology for analysis of objects shape data, received from video sequence of the camera. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/4bc/Efimov_Ilin_rus.pdf In this article we will discuss different ways of analysis of objects shape data, received from webcams. Purpose of this research was development of various areas of augmented reality and computer vision. In the analysis of the video sequence, we can distinguish several steps:
In the future we decide to develop halftone recognition to make object shape restore even more accurate. We can also create variation of described algorithms without using of special marker, but it required bunch of sophisticated changes in it. Described algorithm can be used to get object’s 3D models for create it copy on 3D printer. Next important area for us is augumented reality, because of potential of depth map to resolve problems of real and virtual objects intersections and increased range of objects for tracking. Depth maps also has an ability to create stereographic image from set of frames of video. Analysis of objects shapes is important way of development of computer vision and recognition. | ||
Deniskin Y. I., Dubrovin A. V., Podkolzin V. G. Innovative production life cycle processes quality management on basis of computer aided quality management system. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/5f5/Deniskin_Dubrovin_Podkolzin_rus.pdf The article describes the work on semantic analysis of terms and definitions of national and international standards for quality management. Construction of semantic maps graphically displays the types of information flows within the information system for lifecycle processes quality management. The trend of increasing the number of applications of digital manufacturing enforces to develop new approaches in the field of quality and competitiveness of products. This kind of manufacturing is a relatively new and isn’t explored yet on domestic enterprises wide enough. Objective. Providing an integrated life cycle processes quality management of innovative products within digital manufacturing on basis of the computer aided information support. Subject of research — quality of innovative product lifecycle processes within digital manufacturing. Research methods. The research was performed using methods of the system analysis, graph theory, the principles of total quality management, expertise of quality control, methods of functional modeling (IDEF0), FMEA methodology, universal CASE-tools. Practical value of the work is to create an integrated information support tools for the designing and integrated lifecycle process management on the basis of the fundamental requirements of national and international standards in the field of lifecycle support and quality management, in accordance with the specifics of automated enterprise management systems (ERP). Developed functional and information models may serve as a basis for the rational designing of enterprise process model and for the innovative enterprises structure management. Designed qualitative methods for evaluating the quality of the life cycle processes within digital manufacturing make it possible to provide information support for quality management system foundation (control, management, maintenance, improvement, planning) within digital manufacturing. | ||
Podaruev V. Y. Program code developpment experience based on Galerkin method with discontinuous basic functions of high order of accuracy. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/8a1/Podaruev_rus.pdf The paper enunciates the experience of developing the software based on the Galerkin method with discontinuous basis functions of high accuracy. The purpose of the work consists in describing the specifics of of the program code developing intended for use on a multiprocessor computer system. The methodollogy of the work is based on the modern approach to simulation of complicated 3D flows using Galerkin scheme with discontinuous basis functions. The methodology of this work execution includes theoretical analysis of the method, application of modern approaches to programming, verification and validation of employed ideas and demonstration of the developed code’s suitability for complicated nonlinear calculations. The result of the work are recommendations for the software developing based on modern methods of computational aerodynamics. To develop a software interface for specific codes, it is convenient to use the Python programming language. Before proceedeing to descring the computational domain topology, the calculated grid type (structured or unstructured) should be defined. It is necessary to determine what types of geometric objects are to be worked with. In the case of “serendipian” elements, the desired order of the problem approximation should be selected and the elements for linear, quadratic, cubic, etc. cases should be identified, with further changing only the sets of shape functions, characteristic to the specified elements. It is convenient herewith to realiize these sshape functions in the form of the so-called “lambda” functions included in the C++ standard. The results of this work can be applied for educational purposes in technical universities and in practical works on developing new software in scientific institutes and design offices. The main conclusion of the paper is that a high-order scheme allows diminish entropic errors while calculating the flow after stagnant zones, as well as calculate all the flow specifics, which are characteristic for flow around the high-lift wing with released slats and flaps. Modern programming approaches allow ensure the high code scalability. In addition, the main features of the Galerkin method with discontinuous functions, such as reconstruction of conservative variables, the approximation of convective, diffusion and source terms, Gaussian quadratures, with account for the surface curvature, coordinate transformations using “serendipian” elements, are briefly described. | ||
Krasinsky A. Y., Ilyina A. N., Krasinskaya E. M., Rukavishnikova A. S. Mathematical and computer modeling of rover with elastic suspension longitudinal dynamics. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/3d3/Krasinskiy_Ilina_Krasinskaya_Rukavishnikova_rus.pdf In the paper we provide a method of constructing an accurate mathematical model and solving a steady motion stabilization problem by the example of a simple rover − a four-wheeled mobile single-link manipulator with elastic suspension. It is an actual problem [16] because Lagrange equations of the second kind are not applicable for such systems. Redundant coordinates and equations of motion in M.F. Shul’gin’s form [1-3] are used to model the mechanical part of the manipulator dynamics. Vector-matrix form of the equations is convenient for analysis and control theory and the theory of critical cases [6-8] applying. The algorithm of solving stabilization problem was developed in [10-11]. The manipulator has to move rectilinearly with a constant speed and keep its clamp (with a camera or a scanner, for example) on a specified height. The system has a geometric constraint as the link is connected with a DC motor gear wheel by an inextensible arm AB. As a control action additional tension at the anchor engine is accepted. The wheels are simulated as two springs. Solving the problem consists of a few steps:
Results of numerical computations showed that the control law provides asymptotic stability with respect to all variables. This algorithm was programmed in MATLAB. | ||
Lisov A. A., Chernova T. A., Gorbunov M. S. Modeling of limiting states in the operation of electromechanical transducers. Trudy MAI, 2017, no 95, http://mai.ru//upload/iblock/f10/Lisov_CHernova_Gorbunov_rus.pdf In actual operating conditions of electrical industry’s products the degrading changes of their properties should be accounted for. The object of research is various kinds of electromechanical converters, for which even a slight degradation of the properties leads to the serious technogenic aftermath. Methodological basics for solving such problems were considered and suggested; a number of regularities of degrading changes is established, and mathematical models were developed. Analysis of the characteristic parameters changes allows the four most typical types of functions for describing these regularities: the entire rational functions or polynomials; fractional rational functions; exponential functions; function describing the saturation processes. For each dependence under consideration, examples of the limiting state attainment forecast and the residual resource calculation are given. Models’ building of degrading changes supposes tabulating the measured values and selection of such approximating function, which will provide the least mean square deviation from the tabular dependence. The best results in solving the problems of this kind is ensured by the method of least squares (OLS). Analysis of considered functions degradation of processes’ descriptions allows establish the following: all functions have an initial value, known from the nameplate data on the device in service. Thus, it is expedient while the degradation changes analysis to study not the whole function, but only its degradation deviation. The initial value of the deviation function is zero, so its plot passes through the origin. When determining the number of approximating function parameters their number is reduced by one for the deflection function, therefore decreasing the order of normal OLS systems. A practical tool for predicting the modes of functioning of electrical devices and estimating the residual resource has been developed, and a residual resource has been calculated for the degradation changes described by the dependencies of a different type. Prediction of residual resource is based on the solution of nonlinear equations, in which the degradation deviation function takes normative allowable values. The solution of the equation must be determined by limiting the value of the argument, as the moment of failure. Estimation of the residual resource of the device was performed based on the moment of failure. | ||
Aleroeva H. T., Aleroev T. S. Fractional differential equations and kernels, and small vibrations of mechanical systems. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/09e/aleroeva_aleroev_rus.pdf The article studies the Dirichlet boundary value problem for the equation of motion of an oscillator with viscoelastic damping in the case when the damping order is greater than one but less than two. Such problems simulate many physical processes, in particular, string vibrations in a viscous medium, changes in the deformation-strength characteristics of polymer concrete during loading, etc. Earlier, in the case, when the order of the fractional derivative is less than one, the authors established basic oscillation properties, using the methods of perturbation theory. They are as follows. All the frequencies are simple (i. e., the amplitude function of the natural oscillation of a given frequency is uniquely determined up to a constant factor); the natural oscillation with the lowest frequency (the fundamental tone) does not have any nodes; the natural oscillations with frequency (the j^{th} overtone) has exactly j nodes; the nodes of two successive overtones alternate. It was also shown, that the operator, generated by the differential expression of a second order with fractional derivatives in lower terms and boundary conditions of Sturm-Liouville type, is a Keldysh’s operator. This makes it possible to establish the completeness of the systems of eigenfunctions and associated functions of boundary value problems induced by second-order differential expressions with fractional derivatives in the lower terms and Dirichlet boundary conditions. In the case when the order of the fractional derivative is greater than one, the previously used technique based on perturbation theory for the study of oscillatory properties does not work. In this paper, we investigate the Green’s function of the corresponding problem, which allows us to establish the positivity of this Green’s function. From this fact, some oscillatory properties follow for the equation of motion of an oscillator with viscoelastic damping in the case when the order of the fractional derivative is greater than one. Since the application of the first eigenvalues is usually of the greatest interest in applied problems, the results obtained can be applied to evaluate the study of the natural oscillation with the lowest frequency, and also to establish that the fundamental tone has no nodes. | ||
Kuroedov A. A., Borisov D. M. Effect of averaging method of solid propellant power plant operating parameters on acoustic vibrations damping factor. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/3c3/kuroedov_borisov_rus.pdf The article deals with studying the work process stability in a solid propellant power plant (SPPP) chambers with respect to small pressure perturbations. The research method is based on the energy approach, which allows evaluate the gas flow stability, comparing the disturbances energy inflow and outflow. The aim of this study is the analysis of the two time averaging methods of the SPPP chamber parameters – simplified time averaging widely used in the foreign studies of the SPPP stability (No 1), and common time averaging (No 2). The analysis is based on calculations of the first longitudinal acoustic mode oscillations damping factor for the three types SPPP chambers for various applications with tubular grain. The acoustic disturbances in steady incompressible gas flow propagating in a cylindrical channel with permeable walls are considered. The first oscillation longitudinal mode damping factor is determined with averaging small isentropic perturbation energy equation over the chamber volume and time. The damping factor as a function of the tubular grain radius of the three SPPP types calculated by two time averaging methods was obtained through computational experiment. It was found that for all SPPPs under consideration the work process in combustion chamber is more stable while using averaging No 1 to averaging No 2. The greatest difference was observed for the small-scale SPPP. Relative divergences for small-scale, mid-size and large SSSPs are 61%, 32% and 26% correspondingly. According to the performed studies, a conclusion was made that the time averaging No 2 is more suitable for practical calculations. | ||
Berezko M. E., Nikitchenko Y. A., Tikhonovets A. V. Joint of kinetic and hydrodynamic models by the example of the Couette flow. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/f5f/berezko_nikitchenko_tikhonovets_rus.pdf The problem of setting the boundary conditions on a solid surface for the viscous heat-conducting gas equations becomes very relevant in the case of hypersonic and moderately rarefied flows. The statement of the boundary conditions at the level of gas-dynamic variables results in significant errors for relatively large Mach values (M) and Knudsen (Kn) numbers. Physically adequate formulation of the boundary conditions on active (absorbing or releasing the gas) surfaces is impossible without considering molecular processes. The kinetic models describing the gas flow at the molecular level make it possible to set the physically adequate conditions on the surfaces with different properties for any flow regime. However, the kinetic calculation of the flow field of complex geometry by is rather inefficient. The purpose of this work is the development of a physical-mathematical flow model (KIN_NSF) containing the Navier-Stokes-Fourier model (NSF), «joined» to the kinetic model equation of polyatomic gases. The kinetic model is used in the near-wall Knudsen layer. The remaining flow range is described by the NSF model. In the range of the model, joining the approximating velocity distribution function of molecules is recovered by the parameters determined by the NSF model. It represents the expansion of the local-balanced distribution function in terms of the thermal velocity. The expansion coefficients (unbalanced stresses and heat fluxes) are presented in the Navier-Stokes approximation. The developed KIN_NSF model is efficient enough for the practical applications and at the same time allows setting the boundary conditions at the kinetic level of the gas with the surface interaction processes description. A series of test calculations has been performed on the example of a flat Couette flow in the intervals . The kinetic model equation for polyatomic gases, NSF and KIN_NSF models were tested. The results of the calculations revealed that the KIN_NSF model is not much inferior in accuracy to the kinetic model, and it substantially exceeds it in the efficiency. With the KIN_NSF model required a few dozen times less CPU time than the kinetic model. When describing flows of the dense gases, the economy of the KIN-NSF model does not depend on the Kn number and depends weakly on the M number, which is typical for the NSF model. | ||
Novak K. V., Oleshko V. S., Starikova I. O., Toforov M. S. Analysis of complexes with unmanned aerial vehicles used by special operations forces of the United States of America. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/bd2/novak_-starikova_-oleshko_-toforov_rus.pdf As effective military instruments, used to amplify its political and military influence abroad, mainly in third world countries, the USА is considering special operations forces. One of the actively used in recent years, the types of weapons the special operations forces of the USА are the complexes with unmanned aerial vehicles, which, in order to enhance the effectiveness of special operations forces, capable of solving the following main tasks: – obtaining in advance, or constantly in the course of warfare intelligence information about the enemy by its transfer on control points in real time; the results of targeting on mobile, time-critical and again you manifest to order to command posts, aircraft, ships, and weapons outfitted with equipment retarget in-flight (cruise missiles, sea- and air-based); – jamming weapons and retransmission signals; – defeat of enemy on call of duty provisions in the air or on the ground. Armed forces special operations United States at present-presence of the complexes with unmanned aerial vehicles of various ranges from multi-purpose unmanned aerial vehicles long range reconnaissance unmanned aerial vehicles of small and middle range. Currently, units of the special operations forces of the USA successfully used the complexes with unmanned aerial vehicles RQ-11 “Raven” and the RQ-14 “Dragon eye”, “Puma” and “WASP AE”, PD-100 “Black Hornet”. On the basis of the conducted analysis of tactical complexes of the special operations forces of the USА and considered international experience, it is possible to argue that the Armed forces of the Russian Federation: – is the actual application of tactical complexes with unmanned aerial vehicles in the interests of tactical units and special operations forces; – is it appropriate to conduct scientific research in the development of miniature unmanned aerial vehicles as a component of the advanced equipment of the Armed forces of the Russian Federation; – is it appropriate to conduct scientific research in the field of combating tactical complexes with unmanned aerial vehicles a potential enemy. | ||
Ershov G. V., Murlaga A. R. Unitized ultra-broadband system for helicopters’ individual passive protection. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/d8f/ershov_murlaga_rus.pdf The article discusses passive jamming systems development allowing decrease helicopter signature from prospective observation and guidance facilities in infrared, laser and visible centimeter wavelength ranges. The standard ejection unit, as a part of modern helicopters configuration and meant for false thermal targets jettison, was taken as a basis of the suggested system. The false thermal targets ensure signature reduction only within the infrared wavelength range. Thus, the authors suggest supplementing the standard ejection unit with special ammunition to form the cloud (screen) of volume-distributed composition from nano-structured carbon material (technical carbon of “Veil” brand). While furnishing the standard unit, the volume of the chamber, containing the powder, in the suggested ammunition will be 58.9 cm^{3}. With bulk density of 195 kg/m3 of technical carbon of “Veil” brand the weight of powder contained in the chamber is 11.5 g. The number of the ejected ammunition ensuring the cloud (screen) formation depends on the helicopter type, as well as the types of observation and guidance facilities, weather conditions etc. The efficiency of the suggested engineering solutions was confirmed by the results of laboratory and actual test. These results revealed that a) the transmission factor of the technical carbon of “Veil” brand varies within the range of 7% to 15% within the above pointed wavelengths range; b) the absorption of about 85% is reached with technical carbon concentration of 25·10^{-4} g/ml; c) with technical carbon concentration increase the absorption factor increases either. The system suggested in the article is able to ensure effective protection of helicopters from prospective observation and guidance facilities due to its wide spectral range and unique electrodynamic properties the technical carbon of “Veil” brand. Further studies will include model developing and experimental studies related to the particles’ distribution of the technical carbon of “Veil” brand particles in the cloud (screen) depending on ejection conditions. | ||
Krivoruchko D. D., Kuli-zade M. E., Skorokhod E. P., Skrylev A. V. Spontaneous emission probabilities for ion ХеII and distribution of excited states in low-temperature plasma of Hall-effect Thruster. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/a4c/krivoruchko_kuli_zade_skorokhod_skrylev_rus.pdf Nonequilibrium low-temperature xenon plasma of Hall-effect Thruster (HT) was investigated by spectroscopic measurements in the 250 - 1100 nm range. e Facility and investigation methodology description is discussed in detail in [1]. The problem researched is to find coefficients for all xenon lines using various models and experimental values of the lines intensities, to determine concentrations of excited states (population), to construct distribution of excited states (DES). Within the framework of the six models the probability calculations including radiative transitions related to the lowest levels are considered. The examined probabilities are tabulated. A comparison is made with the experimentally obtained results of papers [20-21]. Based on the spectrum data, a DES was constructed for each position of the recording equipment: 1) the lens was mounted coaxially with the HET stream and "look" at the center of the channel; 2) the radiation was sel ected by an external lens system perpendicular to the axis of the engine at a distance of 1 cm from the cut; 3) the radiation was taken at an angle of 14 ° to the axis of the HET, starting from the channel cut; 4) - in a different plane, from the position 1 to 12 down. The distributions for different parts of the plasma jet 1-4 are of the same nature. For position 2, the distributions were analyzed using the Einstein coefficients calculated with different models. The structure of the DES is sensitive to the choice of the model for calculating the probabilities of radiative transitions. The intermediate type of coupling for the angular dependences of the matrix elements did not lead to the expected result. The DES based on these data had pronounced energy oscillations, what could have been caused by the erroneous determination of the percentage of different states. The use of the LS- coupling in combination with all three models of calculating radial integrals does not give a wide spread of populations. The DES using experimentally determined Einstein coefficients [20-21]agrees well with the results when the probabilities were calculated in the Hartree-Fock-Slater approximation with the LS- type of coupling. The concept of a state vector is introduced, as a combination of the distributions of the excited states of an atom with analogous ion distributions. Just as in atomic physics, for each atom, there is a different level scheme (Grotrian) corresponding to the wavelengths of the ruled spectrum, so any plasma has its own "bar code" in the form of individual distributions of excited states of atoms and ions obtained fr om spectra. | ||
Kanev S. V. Flow of electrons in weak stationary magnetic field. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/671/kanev_rus.pdf The wide spread plasma conductivity models as applied to certain types electric rocket thrusters give results inconsistent with the experiment data on local and integral parameters of plasma in magnetic field. The goal of this article was development of a mathematical model of electrons flow through the magnetic field, which may be used for parameters computation of such kind of thrusters. Analysis of gas discharges in ion thrusters, such as stationary plasma thrusters (SPT) and thrusters with anode layer (TAL), revealed two specific features of magnetic fields used in them. Firstly, the width of the area with magnetic field is comparable to Larmor radius of electron. Secondly, due to plasma sparsity the electron collision with heavy particles are quite seldom, i. e. . Thus, one of the assumptions included into basis of the “classical” plasma conductivity model is not complying. Moreover, the electron drift in the thrusters under consideration is closed. It allows simplify the mathematical model. Analytical study revealed that an extra electrons velocity component is formed in plasma in the specified conditions. This component, in its turn, due to the Lorentz force results in forming the force, impeding the electron flow through the magnetic field. The magnitude of this force appears proportional to the square of vector magnetic potential gradient. Thus, the author managed to obtain analytical equation for energy consumption associated with electron flow through the weak magnetic field. To evaluate the obtained model error and define the area of its implementation the more complex problem with account for electrons dissipation on heavy particles was considered. Analytical solution for a special case was obtained. It allowed define limitations on application of the suggested model more precisely. The developed model’s application to SPT and TAL discharge voltage computation revealed close agreement with the experimental data. | ||
Belousov A. P., Mel'nikov A. V., Khartov S. A. The model of electrons dynamics in a discharge chamber of a high-frequency ion thruster. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/dc6/belousov_melnikov_khartov_rus.pdf Fundamental research of the properties of high-frequency discharge is needed to improve the energy characteristics of high-frequency ion thrusters. And the development for this purpose a simplified physical model of the dynamics of electrons will allow us to quickly numerically estimate the most favorable conditions that ensure the efficient transfer of high-frequency field energy to electrons in the plasma. Analysis of the characteristics of an inductive discharge in the gas-discharge chamber of a high-frequency ion thruster has allowed to determine the main dependences for finding the distribution of concentration and temperature of electrons along the radius of the ionizer. The distribution of the concentration of electrons along the radius of the ionization chamber is determined by the distribution of the potential of plasma arising because more movable electrons leave the plasma volume faster than ions. Using the Harrison and Thompson solution for the flat approximation can be obtained the distribution of the potential of plasma. And, substituting this solution into the Boltzmann equation which connect the potential of plasma and the concentration of electrons, possible to calculate the distribution of concentration of electrons along the radius of the gas-discharge chamber. The distribution of temperature of electrons, depends on the intensity of the vortex electric field in the volume of the discharge chamber. The induced electric fields are determined by the system of Maxwell’s equations. These fields can be calculated by the finite element method in the COMSOL Multiphysics program. The comparison of the obtained numerical results with the experimental data is showed the possibility of using the proposed dependencies for a preliminary assessment of the local plasma parameters in a gas chamber of a high-frequency ion thruster. | ||
Kopylov A. V., Tikhomirov М. A., Mokretsova O. V. Thermal protection systems for combined rocket-ramjet solid fuel engine. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/351/tikhomirov_kopylov_mokretsova_rus.pdf On the basis of multifactorial analysis, computational research and tests carried out constructively-similar samples developed the following thermal protection system structures of a combined rocket-ramjet engine solid fuel (KRPD-T):
Also in work the analysis of use on the outer surface of the housing KRPD-T outer thermal barrier coatings — based low molecular weight silicone rubber to protect against aerodynamic heating. Study outer thermal barrier coatings outdoor temperature is confirmed by testing structurally similar samples. The system of thermal protection allow you to:
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Sinitsin A. A. Calculation of Interplanetary Earth-Mars Low Thrust Transfer without Method of Gravispheres. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/587/sinitsyn_rus_.pdf The article considers the spacecraft interplanetary transfer from circular low Earth orbit to circular low orbit near Mars by propulsion system with constant values of thrust and specific impulse. The main goal of the article consists in null length gravispheres method inaccuracy estimation. Due to the nearness of planets’ phases, the simulation revealed substantial for heliocentric phase value of excessive hyperbolical velocity on the edge of gravispheres. while applying conventional technique, imposing the null value of excessive hyperbolical velocity for the trajectory conjugate phases and the planets’ heliocentric phase. These simplifications affect the transfer effectiveness figures, namely, transfer duration and final mass. Another factor, defining the value of gravispheres method inaccuracy consists in neglecting the long duration of gravitational attraction of the Sun on planet phases, as well as of the planets on heliocentric phase of spacecraft trajectory. The article presents the developed technique for direct determination of spacecraft trajectory (without applying gravispheres method) including Earth, Sun and Mars gravitational attraction effect on a spacecraft (as Newton’s dynamic model). Thrust vector direction is defined from solving variation problem with transfer duration as performance index (minimum time problem) applying necessary optimality condition in the form of Pontryagin’s maximum principle. Maximum principle application allowed simplify variation problem to the three points boundary value problem, solved numerically. Comparison of transfer performance indexes, i. e. duration and final spacecraft mass, obtained by the developed technique implementation, and application of gravispheres method is presented. In the last case on planet phases variants of parabolic velocity and hyperbolic excess velocity with value similar to the direct solution (without gravispheres method applying) is considered. Presented computation results revealed worsening of transfer duration and final mass in the case of applying gravispheres method vs. direct trajectory calculation (4-11% for duration and 2-6% for mass). | ||
Efremov A. V., Alexandrov V. V., Valerov K. V. The research on influence of manipulator type and kind of control signal on pilot-aircraft system characteristics. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/130/efremov_-aleksandrov_-valerov_rus.pdf Two types of possible feel system are considered. One of them is the displacement sensing where the signal transmitted to flight control system is proportional to the stick displacement. The other one is the force sensing where the output from the manipulator is proportional to the force. The analysis of pilot model taking into account two loops in neuromuscular system demonstrated the potentiality of the force sensing type of the feel system in decrease of the phase delay in pilot describing function. The ground-based simulation was carried out for the exposition of feel system types effects. For that purpose the pitch and roll tracking tasks were executed for the different controlled element dynamics, stick stiffness, for the side and central sticks. The experiments demonstrated that usage of the force sensing type of the feel system causes the decrease of pilot phase frequency response characteristics for all investigated variables. The effect is higher for the controlled element dynamics with improved flying qualities and smaller manipulator stick stiffness. The phase delay was decreased up to 120 deg in longitudinal channel and up to 140 deg in lateral channel. The increase of the spring stiffness decreases this effect up to 50÷70^{0} in lateral and longitudinal channels. The usage of force sensing type of feel system causes the decrease of variance of error up 40÷70^{0} in the both channel. Such effects took place for the side and central sticks too. The experiments demonstrated that in lateral channel pilot generates higher phase delay in comparison with longitudinal channel especially for the case of dynamics with deteriorated flying qualities. | ||
Makarenkova N. A. Solar sail spatial position control. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/35a/makarenkova_rus.pdf The solar sail, represented in the form of a thin rotating mirror film attached to a cylindrical rigid insertion, is considered. The flywheel is introduced to compensate the kinetic moment of the “rigid insertion—film” system. The author suggests to use albedo’s changes for creating the control moment. It will result in the structure elements’ kinetic moments vectors non-collinearity. As a result, the spacecraft will start rotating around the axis coinciding with the sum of these vectors. To study the advantages of the described control method, an assessment of the time and energy required for the solar sail reorientation in the case of a structure without compensating flywheel and with its presence is made. It is established, that the change in the angular velocity of the “rigid insert—film” system due to the tangential component of the light pressure force is 0.01% of the initial value. In view of this value’s smallness, a decision was taken to neglect it in the further investigation. The shape of the film surface under the effect of the gyroscopic moment occurring while the sail surface albedo changing was established. The dependence of the film deviation from the plane of the rigid inserting from the angular velocity of the sail turn was obtained. The results of the conducted studies reveal that for a solar sail with a flywheel the turn time decreased by more than two times, and energy consumption decreased almost by factor of seven, compared to the solar sail structure without a flywheel. | ||
Starovoitov E. I. Space system reflectors’ metallization selection for orbital Earth surface lighting. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/477/starovoytov_rus.pdf Energy consumption growth continues worldwide and human activities negative consequences are manifested in ever-increasing degree. Electric power generation for the nighttime lighting leads to heavy consumption of hydrocarbon fuel. The negative consequences for the ecology can be reduced by dint of space technologies, using reflected sunlight for the nighttime lighting. The article analyzes spectrum of reflected Sun radiation from metallic coatings of various types of reflectors’, used in the space system for orbital Earth surface lighting. It is known by now that artificial lighting can disrupt at night photo-biological reactions of various living bodies, including humans. The short-wavelength spectrum region should be pointed out specially, featuring pronounced photo-biological effect. Thus, the author suggests to reduce the reflected Sun radiation flux in short-wavelength region (ultraviolet radiation and blue color), exerting the strongest biological effect. To ease the load on operator’s visual organs and reduce the undesirable effect on ecology, various metallic coatings are recommended for use in the orbital lighting system. Five types of metallic coatings for space reflector, namely aluminum, silver, titanium, copper and golden, were considered in the article. Reflectors with silver coating are suitable for ultraviolet radiation reduction (0.28–0.38 mcm) in reflected radiation, and for ultraviolet radiation reduction (0.28–0.38 mcm) and lighting by blue color(0.44—0.48 mcm) reflectors with copper and golden coatings can be used. At the same time, taking into account the entire set of requirements, titanium coating is optimal choice of reflector coating. | ||
Saba A. ., Thanh P. C. Optimization of Solar Energy Harvesting While Powering Wireless Methane Sensor from Renewable Energy Sources. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/1b9/saba-akbari_tkhan_rus-.pdf Recently, there has been growing research interest in the application of wireless sensor networks (WSN) for monitoring of gas concentration at industrial facilities and in urban areas. Methane monitoring is one of the areas where WSNs can be used. In the absence of grid power, the operation of wireless methane sensors is determined by the capacity of their onboard batteries. The battery replacement or charging procedure can become a limiting factor for wireless sensor networks consisting of a large number of nodes or those located in difficult to access areas, such as networks used in some oil and gas projects. In this work, a hybrid power supply based on renewable energy sources is developed to increase the autonomous operation time of wireless methane sensors. The power supply converts solar and wind energy into electrical energy stored in supercapacitors. This paper describes two algorithms allowing increase the efficiency of supercapacitors charging in hybrid power supplies. The first one is a maximum power point tracking technique (MPPT) by finding what maximum power from solar panel can be achieved. According to the algorithm, maximum power point tracking is performed by changing the discharge time and comparing the output power of the solar panel before and after these changes. Load balancing mechanism ceases in case of obtaining a maximum power point. Rebalancing is performed by periodically changing the inductor discharge time. The second algorithm provides an efficient switching mechanism for supercapacitor charging. Both algorithms are applied to a power supply, which harvests solar and wind energy and is used for powering an autonomous wireless methane sensor. | ||
Kazakov V. A., Senyuev I. V. Measuring temperature distribution on the sample surface while testing in thermal wind tunnel. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/b26/kazakov_senyuev_rus.pdf While conducting experiments in the thermal wind tunnel it is necessary to measure the temperature distribution on the sample surface within the range up to 3000°C. This task is solved with pyrometry, allowing temperature measuring by equilibrium radiation’s registration of the studied object in visible or near infrared spectral range. The complexity of the optical temperature measurement is caused by the absence of precise information on the tested model’s materials emissivity. Very often, these materials are novel, and information on their optical properties is inaccessible. Furthermore, the chemical composition of the sample surface may alter during the experiment and, in some cases, the surface destruction may occur. All these processes can change surface emissivity significantly. It should be noted, that emissivity change over the surface could appear rather non-uniform. Thus, it is necessary to use temperature-measuring methods, which do not require information on the tested object emissivity. As a rule, the tested objects are axisymmetric or flat bodies, and, therefore, the information on a temperature distribution along one line on the sample surface is sufficient. The multi-channel spectrometer based on digital CCD camera was developed. It ensures a momentary acquisition of emission spectra along a certain line. The spectrometer consists of two lenses, slit diaphragm, diffraction grating and CCD camera with a lens. The radiation of the heated object is passing through two lenses and falls on diffraction grating. Lenses are combined to form the Kepler telescope scheme, producing the parallel beam. The third lens is used to form the spectral image of the slit on CCD array. The developed multi-channel spectrometer was tested in TsAGI together with NRU MPEI. Tests proved the performance of the spectrometer and the ability to measure temperature distribution in the absence of emissivity value of the sample material. | ||
Amenitskiy M. V. Medium and heavy class uavs control system potential threats analysis. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/107/amenitskiy_rus.pdf The goal of the article consists in substantiation of aerial flying vehicles’ (UAV) control systems analysis with a view to the present ability of control interception and confidential information discredit. The author developed the UAV control system’s information influence algorithm based on STANAG 4586 Edition No 3 Control System (UCS) Unmanned Aerial Vehicle (UAV) NATO Standardization Agreement 4586. The presented algorithm determines possible channels for impact. The basic criterion for determining the system element as subjected to an external impact is existence of communications links, passing through the space points accessible for an intruder. To confirm the impact possibility, the supposed attack scenario is described using the suggested impact vector. The article considers various impact directions, which goal consists in intercepting control over the UAV, and reveals various merits and demerits of each of them. The UAV control system information flows algorithm was developed. The revealed impact vectors were analyzed by the “strengths and weaknesses” method. Several requirements to activities on UAV prototype model design management aimed at information security enhancement of the UAV control system were determined. It was revealed in the course of the studies that the most effective impact on the control system of medium and heavy class UAVs is the impact on the systems of spatial positioning and navigation. | ||
Anisimov O. V., Kurchidis V. A. Diagnostic information formation in the form of electronic equipment electrical circuits’ fragments. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/b17/anisimov-kurchidis_rus.pdf Transition to the electronic representation of electric circuits in the existing information support systems does not ensure significant time gain while forming diagnostic information in the form of electric circuits’ fragments. It restricts the information support systems’ abilities on reducing duration of technical diagnostics and recovery of electronic equipment of complex technical systems. The time of complex technical systems recovery can be reduced by decreasing the time necessary for forming diagnostic information in the form of electric circuits’ fragments. The proposed method contributes to the recovery time of complex technical systems reduction by improving the efficiency of information support automation means of the diagnostic systems. This method allows forming diagnostic information in the form of electric circuits’ fragments based on their structural and functional properties’ description in object notions and terms of natural language. The presented method is based on the mathematical apparatus of the theory of sets and relations, predicate calculus, the theory of formal languages and grammars. There is a good reason to consider the obtained results as methodological basis for the modern information support systems for technical diagnostics, oriented on applying an electronic folder of the product as an information base of such systems. It contributes to functionality enhancing of the relevant information support systems. Implementation of the proposed method allows repeatedly reduce the diagnostic information formation time of electronic equipment electric schemes in the form of fragments and to decrease the recovery time of complex technical systems up to 14%. From a practical point of view, the proposed method ensures a time reduction of the diagnostic information formation. This method creates a formalized base for the architecture development of information support system for technical diagnosis process. The aggregate of the obtained results is aimed at electronic equipment models and methods representation on account of the necessity to form diagnostic information in the corresponding application domain. This work is a starting point for further research in the field of process of information support of the complex technical systems’ technical diagnostics. The developed method of the diagnostic information formation while complex technical systems recovery is based on implementation of the aggregate of models and methods, ensuring concordance of conceptual and schematic and graphical representation of radio electronic equipment based on elements’ patterns of electric circuits. | ||
Osipov N. A., Shavin A. S., Tarasov A. G. Methods of identification interference taking part in robotic systems broadcasting. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/d4c/osipov_shavin_tarasov_rus.pdf In the conditions of electromagnetic radiations impact, various by the nature of emergence and nature of distorting influence, for increase of autonomy of robotic systems from positions of information transfer it is necessary to solve two problems: to provide authentic transfer of important and technological information and to distinguish the transferred information distortion reasons. The Methods of identification interference, is based on the solution of a problem of classification. As the signs describing distorting influence of hindrances, estimates of random variables which characterize are used, how many time each important and technological team, taking into account the compelled repetitions was transferred, a Fisher’s linear discriminant strengthened by Bagging algorithm is chosen as the qualifier. The methods of identification interference operating in the communication channel of robotic systems, including three main points is developed: – formation of a vector of signs of distorting influence of hindrances; – identification of a vector of the signs characterizing distorting influence of hindrances; – the alarm system to the operator on management point. In article offers on realization of a technique of identification of hindrances in intellectual system of recognition of the transferred information distortion reasons are presented. Application of the developed methods of identification interference in common with way of non-uniform error-detected coding allows to localize the information distortion reason in a communication channel and to exclude possibility of passing of unreliable information. The methods of identification interference can be realized in intellectual system of recognition of the transferred information distortion reason and to be a segment of system of support of decision-making. | ||
Arnol'dova E. A., Balalaev A. Y., Zaytsev A. G. Effectiveness evaluation results of multiple-beam self-focusing adaptive antenna arrays of radio-electronic systems. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/5c9/arnoldova_balalaev_zaytsev_rus_1.pdf The goal of the paper consist in Effectiveness evaluation results of multiple-beam self-focusing adaptive antenna arrays of radio-electronic systems. The paper considers information radio-electronic system searching for radiation sources in conditions of complex signal-jamming environment, characterized by a priori uncertainty relative to their number and spatial position. The radiation sources’ signals feature overlapped energy spectra. The search is performed by the adaptaion results of the multiple-beam self-focusing adaptive antenna arrays as a part of antenna block of information radio-electronic system. The adaptation result represents separate estimations of the radiation sources signals’ amplitude-phase distribution at the aperture of the radio-electronic system antenna block. It allows form separate spatial channels for receiving the signals from radiation sources according to maximum criterion of signal/interference + noise ratio. The signal detection is based on Neyman-Pearson criterion by sampling results analysis, formed at the output of each spatial receiving channel. Estimation errors occurrence of vector of parameters of the multiple-beam self-focusing adaptive antenna arrays results in signal/interference + noise ratio decrease in spatial receiving channels, and, as a consequence, to efficiency reduction of radio-electronic systems by criterion of “correct detection probability”. Evaluation of the total error’s fluctuation value of the vector of parameters of the multiple-beam self-focusing adaptive antenna arrays was executed using a well-known estimation technique, as well as according to the simulation results of the considered adaptation algorithms. The obtained results revealed the parameter, mainly affecting the fluctuation value in evaluations of amplitude-phase distribution formed according to the results of the multiple-beam self-focusing adaptive antenna arrays adaptation. This parameter is angular misregistration of the radiation sources between each other. At keeping herewith the equality of the radiation sources’ angular positions the fluctuation error value would be affected by their number and bandwidth value of the self-adjustment closed loop of the multiple-beam self-focusing adaptive antenna arrays. | ||
Linkevichius A. P. Optimization method of adaptive phased antenna array technical state monitoring and control complex. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/044/linkevichius_rus.pdf The goal of the work consists in optimization method development of decision-making on technical servicing (TS) of adaptive phased antenna array (APAA), including the structure of works, periodicity and TS duration. The decision-making on servicing and recovery is realized in the framework of the unified APAA technical conditions monitoring and control complex, which is developed using reliability characteristics’ modeling, and internal control systems abilities. The research methodology accounts for the availability of the APAA hardware and software components and uses modern logical-and-probabilistic methods for the reliability analysis of the systems under restoration, based on reliability flowcharts. The problem of reliability characteristics optimization (probability of no-failure and readiness factor) is formulated as the basic method for adaptive TS. Its practical realization is based on implementation of numerical methods for solving an optimization problem. The author suggests a design method of a complex for monitoring and control of technical state of prospective APAAs based on complex use of built-in monitoring data and numerical solution of optimization problem. To that end, the APAA reliability model, accounting for its specificity as highly reliable information system and including the redundancy specifics, was developed successively. This complex based on practical use of the reliability model allows compute the content and structure of TS complex, which will ensure the optimal combination of duration, scope, TS periodicity and APAA reliability characteristics (readiness factor optimization). The obtained results can be applied in the field of reliability increasing and operational life extension of APAA and radar stations in total. | ||
Izmaylov A. A., Volkov A. P. Low – profile wideband antenna with improve pattern, using artificial magnetic conductors (AMC) surface ground. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/706/izmaylov_volkov_rus.pdf Active antennas’ array are the main type of perspective aviation and space radar complex of different appointment, with the wideband of working frequencies, consist of vibrator systems, which located over the metal screen. One of the important parameters either for aircrafts and for space systems - is profile height of antenna. As for aircraft, it is important to protect aerodynamics of airplane, for space systems, it is important for compact location antenna inside fairing. The perspective method of lowering the profile height is using periodical microwave composite structures with parameters of artificial magnetic conductors (AMC). AMC structures working in the quasi-static field (wave length more than period of structure) and defined by equivalent parameters in quasi-static approximation. The tangent component of magnetic field on AMC structure is equal to zero, and reflective coefficient is +1. The paper presents the composite L – a band structures to improve characteristics of antenna’s system. AMCs have been chosen as design concept of the baseline array element due to the significant size of reduction they can offer. Although the majority of satellite communications operates at frequencies above L-band, there are interesting opportunities for satellite communications in the very high frequency (VHF)/ultra-high frequency (UHF) spectrum. A standard printed square patch has been selected as reference low-profile element. The binary patch emitter was chosen to improve the directive characteristics of antenna. Desiged antenna has the lateral dimension of 14 millimeters (0.093λ_{0}), staying wave ratio below 2, and directivity 10 dB, working band of frequency is 40%. Traditional case of location vibrator over AMC surface compared with developed antenna. | ||
Korolev V. O., Gudaev R. A., Kulikov S. V., Aldohina V. N. Solution of a problem on object’s type recognition based on antennae's directional pattern as a feature. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/4d0/korolev_gudaev_kulikov_aldokhina_rus-.pdf The goal of the article consists in object type recognition algorithm developing, based on antennae system’s direction pattern. To achieve this goal the authors suggest the distance function use, which determines the difference between various radiation pattern cuts of the antennae systems. The decision-making on the type of the object under recognition is performed using Student criterion. The algorithm proposed in the article allows the object recognition performing based on directional diagrams with the ability of the significance level variation. Based on the presented data, the authors draw inference on the possibility of the object type recognition problem solution by applying the directional pattern of the antennae system, constructed according to the measurement results, as a recognition feature. The proposed algorithm allows perform the object type recognition based on antennae directional pattern, constructed according to the measurement results. The problem is topical, notwithstanding the difficulties associated with multiple beam structure of directional patterns of antennae systems. Addition of new recognition features allows describe the object in more details and increase the probability of the object recognition correctness according to features aggregate. | ||
Boev S. F., Zyuzin A. V., Kostrykin P. A., Khaibutov K. E., Khaibutov M. E. Possibilities of application of multifrequency quasinoise signals in the conditions of conducting radio engineering intelligence by the opponent. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/5c8/boev_zyuzin_kostrykin_khaybutov_khaybutov_rus.pdf The purpose of article is assessment of reserve and consideration of a possibility of application of multifrequency quasinoise signals in reserved radio engineering systems in the conditions of conducting radio engineering investigation by the opponent. On the basis of a mathematical model of the broadband multi-frequency quasinoise signal synthesized with use of conversion of Jacobi-Angera in article the method of formation of the considered broadband signal realized on the modern element basis is considered. It is shown that generation of a multi-frequency signal is carried out on the basis of the harmonic phase shift keying of basic narrow-band accidental process which is rather just realized in practice with normal distribution of the instantaneous values, by expansion in a row on Bessel functions of the first kind. The multi-frequency quasinoise signal described in article in the form of a pica of a body of uncertainty in the required intervals on time of delay and on the Doppler shift on frequency is close to a noise signal. For certain initial conditions — equality of a band of the initial narrow-band accidental process and frequency of phase harmonic shift keying, the range of a multi-frequency quasinoise signal becomes continuous and shumobodobny. The dependences of assessment of an index of Lyapunov and probability of disclosure of a signal structure on frequency change of phase shift keying of MCh KSh of a signal calculated by means of simulation modeling in case of the modified interpolation method allow to conclude that in case of increase in frequency of phase shift keying there is a rise of values of the considered index and reduction of probability of disclosure of structure of a signl. It occurs in connection with proportional broad banding of frequencies of the occupied MCh KSh a signal. Application of multi-frequency quasinoise signals of big duration and occupying the considerable frequency band will allow to increase reserve of operation of radar station in the conditions of guiding by the opponent of radio engineering investigation, saving at the same time high resolution capability on range and speed. | ||
Ibragimov D. N. The minimum-time correction of the satellite's orbit. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/a4d/ibragimov_rus.pdf The minimum-time problem of the correction of the movement of the satellite is considered in this paper. The orbit of the spacecraft is assumed to be circular. Correction Correction is carried out by means of low-thrust engines capable of generating acceleration in the radial and transverse directions. Controls are assumed to be ideal and impulsive. It is proved that the initial problem can be reduced to the minimum-time problem for the linear non-stationary system with discrete time and limited control. The solution of the minimum-time problem for a non-stationary linear discrete-time system is based on the use of the class of sets of 0-controllability — such sets of states of the system from which the origin can be reached in N steps, starting with step k. For the case when the set of feasible controls is a strictly convex body with non-empty interior, an analytic description of the sets of 0-controllability is constructed: each set can be represented as the algebraic sum of strictly convex sets, i.e. it is also a strictly convex set. The lemma on the uniqueness of the expansion of the boundary point of the sum of two strictly convex sets is proved. It is possible to construct a criterion for the optimality of the trajectory of the system and control on the basis of this lemma. The trajectory and controls is connected with each other by a system of conjugate vectors. The obtained results are formulated in the form of the maximum principle. It is also proved that the initial state of the conjugate system is a normal to the set of 0-controllabillity, whose boundary point is the initial state of the control system. For the case, when a set of feasible controls is an ellipsoid, an explicit form of optimal control is proposed. It is proved that if the initial state is an internal point, then the maximum principle becomes incorrect, and optimal control is not unique. Nevertheless, an algorithm is proposed that makes it possible to reduce the given case to the considered one. The obtained theoretical results are applied to the problem of correcting the satellite’s orbit. The results of the calculations are given in the table. | ||
Belyaeva O. V., Paschenko O. B., Philippov M. V. Fast bilateral filtering of aerial images based on decomposition of spatial filters. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/22e/belyaeva_pashchenko_fillipov_rus.pdf The paper considers the problem of fast bilateral filtering of aerial photographs, which allows eliminate small-sized noise and interference, while maintaining sharp boundaries of the objects, necessary for the initial frame processing. Hence, the emphasis is increasing the rate of bilateral filtration as an important stage of the frames processing and restoration. To solve the problem, a fast method of bilateral filtering based on decomposition into independent spatial filters, which allow aerial photographs filtering by several processes simultaneously is considered. To achieve the processing speed of the bilateral filter, a method based on decomposition into recursive Gaussian spatial filters is proposed. Unlike the ordinary bilateral filtration, the presented filter can be parallelized. According to the method, N sets of linear independent filters (components) are computed based on N ranges of pixel intensities on the processed frame. The number of ranges is user-defined (from 2 to 255). The remaining components are computed by bilinear interpolation from the already obtained components. Each component requires computation of two filters, rank and spatial. Hence, the computational complexity of the method will depend on the calculation of the spatial filters in the N components. The Gauss kernel approximation proposed by Deriche are used in the article for the spatial filters quick computing. This allows increasing the rate by several times, using the pre-calculated filter coefficients that specify the form of the Gaussian function, instead of costly computing the Gaussian distribution of each pixel in the frame. The coefficients are calculated from the infinite impulse response of the Gaussian filter, which can be represented by a recursive sequence with constant coefficients. Thus, the article reduces the time of bilateral filtration due to bilinear interpolation over N independent spatial filters. The time for calculating the spatial filters is reduced due to the use of the fast Gaussian filtering method by Deriche based on constant coefficients. The article also uses parallel calculation of independent components of the proposed method of bilateral filtration. The steps, proposed in this article allow get real-time results. | ||
Dudakov N. S., Makarov K. V., Putyato S. A. Model of real-time information systems for problems with a wide range of input data. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/70b/dudakov_makarov_putyato_rus.pdf The purpose of this article is database modelling for real-time special-purpose systems. It is shown that the use of the all-purpose client-server databases for solving the air force and air defense tasks leads to poor query performance. In some cases, the use of more simple distributed databases allows reducing the query time by 90%, but the amount of data does not allow using them as a single solution. Given the limitations of the scientific and methodological methods for evaluating the effectiveness of the database, the article offers a method of modeling the database, which allows to parametrize data and evaluate database performance. Database modelling helps to carry out the management structure of the database. Database modeling is made by mathematical methods of queuing theory, the DBMS performance criteria are based on the average execution time of queries to the database. This article provides a method for constructing an optimal database structure when using a distributed inhomogeneous database for processing of data with a wide range of characteristics. Restrictions in optimization problem are based on database load. The optimization problem is reduced to the Boolean satisfiability problem — the problem of determining if there exists an interpretation that satisfies a given Boolean formula. The variation of the branch and bound algorithm is used to solve the SAT-problem. It is shown that the design of real-time database management system based on database modeling techniques can significantly increase the performance of data processing. This article provides a model of a database management system as a queuing system. It is shown that the application of optimal control database structure allows you to double the capacity in dealing with real-time heterogeneous tasks. | ||
Gurevich O. S., Kesselman M. G., Trofimov A. S., Chernyshov V. I. State-of-the-art wireless technologies: problems of application onboard an aircraft. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/223/gurevich_kesselman_trofimov_chernyshov_rus.pdf Many realizations of wireless technologies found application in various technology areas. Intensive search process for the trends of wireless systems and units implementation, allowing rapidly gain an appreciable economic effect, commenced in aviation industry. Expert judgments reveal that wireless technologies implementation will allow develop highly efficient aircraft control, monitoring and diagnostic systems of new generation, reduce weight and size by 20–40%, increase reliability and reduce system’s maintenance cost by 5–8 times. The onboard wireless sensor network application in onboard systems, not critical for the flight safety, can be considered successful. Wireless technology application in such mission-critical systems as flight or engine operation control is associated with a number of contradictory requirements. Thus, the reliable data transfer between network nodes at a speed of 30–100 Hz and accounting for the signal decay requires transceivers power increase onboard an aircraft. However, onboard wireless units power supply from standalone power sources, prevention of radiation effect on neighboring radio channels and electronic equipment requires low energy consuming. The article analyzes materials of foreign firms on studying the possibility of wireless systems based on protocols of IEEE 802.11 standard application onboard an aircraft. The results of studying the possibility of narrow-band wireless data transmission at the frequency of 868 MHz in wireless aircraft engine automated control system are presented. Experiments were conducted on laboratory complex CIAM with various variants of central radio module shielding by fuselage, and wireless sensor shielding by the engine nacelle, and various distances between them. The article shows that with complete screening simulation and distance of more than 13 m the information channel errors occurred, and from the distance of 15 m complete loss of connection took place. The wireless information channel failures were not observed for the other variants of shielding in the survey distance of 30 m. The main problems of applying wireless technologies in the aircraft onboard systems are as follows: – ensuring reliable wireless data transmission with the required rate and at a predetermined distance; ensuring electromagnetic compatibility (EMC) of wireless sensor network with onboard avionics systems under tough operating conditions on and aircraft and engine; – reducing power consumption of wireless electronic devices for control and monitoring systems, as well as the system for technical condition diagnostics of an aircraft and engine. | ||
Terentiev M. N. Review of Publications on Wireless on Sensor Networks Self-Organization. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/43d/terentev_rus.pdf This paper is devoted to various aspects of wireless sensor networks (WSN) self-organization. The WSN specific features distinguishing them from a more general class are revealed. These features are as follows: directions of data flows, nodes mobility and limited resources. The article formulated the main WSN performance indicators, such as network lifetime, reliability, scalability and message transmission rate. With reference to the WSN, the following principles of self-organizing systems developing are considered: local interactions rules that achieve global goals developing; ceasing a perfect interaction seeking; implicit coordination application; reduce the information volume on the system state; developing the protocols adapted to the changes. The article substantiates the importance of the general self-organization mechanisms (positive and negative feedback, nondeterministic behavior, nodes interaction) in various WSN functioning protocols and methods, such as MACA, S-MAC, PCM, SMACS, SFSN, flooding, AODV, OLSR, hierarchical routing. Based on the analysis, the conclusion was made on the impossibility of developing a fully functional WSN with the agreed values of its performance indicators without developing a unified method of the WSN functioning based on the self-organization principles. | ||
Kindinova V. V. Model of problem analysis of the warehouse logistics object in aviation. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/d01/kindinova_rus.pdf The problem of increasing the efficiency of the operation of the object of warehouse logistics in the example of a warehouse of aircraft parts is considered. As performance measures are considered indicators adopted in queuing theory, characterize the performance and loading facility. To solve the problem developed simulation system based on the integrated use of the conceptual, analytical and simulation methods. The simulation model of problem analysis is an important part of the simulation system, it allows to investigate low-level operating processing processes, evaluate alternatives, develop recommendations for the modernization of processes. The model of problem analysis is implemented with the use of a hybrid approach. It is developed on a modular basis, which allows one to integrate within the framework of one model elements described by heterogeneous mathematical schemes. The approach of modeling the input stream of a complex structure has been developed, the requests of which undergo multiple splitting, corresponding to the transition from one technological process to another. Application of the developed approach to modeling input stream of the detailed presentation level, makes it possible to configure both deterministic and random input with group heterogeneous requests. The approach allows to obtain the following parameters of the functioning of the object warehouse logistics: the waiting time and the start of the service pack; delays inside the pack; packets delay, the number of requests in the system. The dynamics of changes in these parameters is necessary tracked, since the group receipt of requests significantly worsens the performance of the system in comparison with the general arrivals of the same average intensity. Unlike existing approaches, the proposed approach assumes the representation of the input stream by a set of interrelated agents, which allows modeling the input stream with group heterogeneous requests. The model of input stream is implemented using the agent-based approach of simulation modeling. The algorithms of generating initial data for modeling of the random input are developed. Simulation experiments were performed: estimates of workload and downtime was obtained; the effective technology of unloading pallet was identified; the limiting capacity of the acceptance zone was calculated. | ||
Merkulov I. E., Endogur A. I. Supersonic aircraft's welded compartment model development with account for constructive-technological scheme. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/973/merkulov_enogur_rus.pdf The article describes the approach to modelling welded sections of supersonic aircraft with account for their constructive-technological schemes. It based on possibility of accounting for the sequence of factors at finite element analysis, such as, residual tensions caused by welded zones shrinkage, model variability of material sections and their stiffness, etc. The current state of a problem regarding developing of mathematical models of welded structures and their subsequent optimization is analyzed. The proposed method of system synthesis of a section structure considered an order of welding assembly of section design. The developed finite element model of a welded compartment with account for the residual tension is based on modification of a method of forces better known as an “inherent strain method”. This method comprises some thermal-affected zones of a welded section initial design for obtaining pre-tensed state of a compartment. The modeling results revealed distribution changes of operational deflections of the section panels when the residual stress was introduced previously by the bearing. Application of the developed model allowed obtain at a time the stress-strain state dependencies of the welded sections fr om the design data and optimize the top panel thickness. The developed aircraft’s welded compartment model allows evaluate the effect of constructive-technological scheme on its stress-strain state. Applying this model the authors will solve various optimization problems containing requirements and restrictions to allowable stresses, such as deflections magnitude, buckling modes, weight lim it, etc. The solution of such multifactorial, multi-parametric optimization will appreciably reduce timing for a product study and development. | ||
Egorchev M. V., Tiumentsev Y. V. Neural network based semi-empirical approach to the modeling of longitudinal motion and identification of aerodynamic characteristics for maneuverable aircraft. Trudy MAI, 2017, no 94, http://mai.ru//upload/iblock/b8b/egorchev_tyumentsev_rus.pdf The simulation problem for longitudinal motion of a maneuverable aircraft is considered including identification of its aerodynamic characteristics, such as the coefficients of aerodynamic axial and normal forces, as well as the pitch moment coefficient. This problem is solved in the class of modular semi-empirical dynamic models that combine the possibilities of theoretical and neural network modeling. This approach differs significantly from the traditionally accepted method for solving problems of this class [6-8], based on the use of the linearized model of the disturbed motion of the aircraft and using the representation of the dependencies for the aerodynamic forces and moments acting on the aircraft in the form of their expansion into a Taylor series, leaving in it, as a rule, only members not higher than the first order. Accordingly, the solution of the identification problem with this approach is reduced to reconstructing from the experimental data the dependences describing the coefficients of the Taylor expansion, in which the derivatives of the dimensionless coefficients of the aerodynamic forces and moments with respect to the various parameters of the motion of the aircraft are determining. In contrast, the semi-empirical approach realizes the reconstruction of the relations for the force coefficients and moments as some whole non-linear dependencies on the corresponding arguments, without resorting to their series expansion and to linearization, i.e. the functions themselves, represented in the ANN-form, are evaluated, and not the coefficients of their expansion in a series. Each of these dependencies is implemented as a separate ANN-module, built into a semi-empirical ANN-model. Derivatives etc. if necessary, can be found using the results obtained during formation of the ANN-modules for the coefficients of forces and moments within the semi-empirical ANN-model. A mathematical model of the longitudinal motion of a maneuverable aircraft is derived, which is used as a basis in the formation of the corresponding semi-empirical ANN-model, as well as for the generation of a training set. An algorithm for such a generation is proposed, which provides a fairly uniform coverage of the possible values of state variables and controls for the maneuverable aircraft by training examples. Next, a semi-empirical ANN-model of the longitudinal controlled motion of the aircraft is formed, including the ANN-modules realizing the functional dependences for the coefficients . In the process of learning the obtained ANN-model, the identification problem for these coefficients is solved. The corresponding results of computational experiments characterizing the accuracy of the formed ANN-model as a whole, as well as the accuracy of the solution of the problem of identification of aerodynamic coefficients are given. | ||
Aslanov V. S. The swing principle for deploying of a tethered system for the delivery of the capsule to Earth. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/2cd/aslanov_rus.pdf The field of space tethers has received very much attention in recent decades. The central advantage of using tethers in many of these applications is that very little fuel needs to be consumed. The tethered systems offer numerous ways of beneficial implementation on modern spacecrafts and allow to perform multiple tasks including such as payload delivery from the Earth orbit. It is the task of payload delivery from an orbit is the closest to wide practical realization from all other space tether’s tasks. As demonstrated by the mission of YES2 a re-entry capsule can be returned to Earth by a tether. Braking of the capsule is achieved using momentum provided from the swinging tether. The more a deflection angle of the tether from the local vertical, the more braking effect of the capsule is achieved. The goal is to find the control law that allows one to increase the angle of deflection of the tether from the local vertical, i.e., to increase momentum provided from the swinging tether. This control law can be applied to the final phase of the deployment of the tether, both for dynamic so the static deployment. The control law is based on the principle of a swing with variable length. Simulations show that the system can be controlled quite well using the proposed control law for the tether length rate. For stability analysis in the neighborhood of the equilibrium position is used Lyapunov function. Opportunity to perform separation of the capsule is shown for to oscillation of the tether system, and for the rotation. The control method allows to reduce a required tether length for deliver capsules on Earth’s surface. Using this method, we have shown that it is possible to diminish tether length at 5 km as compared with YES2 mission. Results of the numerical modeling showed that the control law is effective for the final phase of the tether deployment, when the initial deployment occurs by means static or dynamic scheme. | ||
Semenov M. E., Solovyov A. M., Popov M. A. Stabilization of unstable objects: coupled oscillators. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/9f3/semenov_solovev_popov_rus.pdf As is known, the problem of inverted pendulum plays a central role in the control theory. In particular, the problem of inverted pendulum (as a test model) provides many challenging problems to control design. Due to their nonlinear nature, pendulums have maintained their usefulness and now they are used to illustrate many ideas emerging in the field of nonlinear control. Typical examples are feedback stabilization, variable structure control, passivity-based control, back-stepping and forwarding, nonlinear observers, friction compensation, and nonlinear model reduction. The challenges of control made the inverted pendulum systems a classic tool in control laboratories. It should also be noted that the problem of such a system stabilization is a classical problem of the dynamics and control theory. Moreover, the model of inverted pendulum is widely used as a standard for testing of control algorithms, such as PID controller, neural networks, fuzzy control, etc. The article investigates the dynamics of a mechanical system consisting of two inverted pendulums hinged on the moving platform and coupled by a spring. The force applied to the platform causing its horizontal motion is treated as a control. The purpose of this work consists in solving the problem of pendulums stabilization in vertical position using the horizontal motion of the platform at presence of the information on the angles of deviation. To solve this problem, we developed the algorithm of the pendulums stabilization near vertical position, found the stability zones and their dependence on the spring stiffness. | ||
Volkov V. A., Semenov V. V., Sidhu J S. S. Wave drag of planar periodic relief structures. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/73e/volkov_semenov_sidkhu_rus.pdf For smooth and piecewise smooth planar relief structures with any periodic profile, within the framework of linear theoryan exact formula, linking the total wave drag coefficient of the aforementioned finite relief structures and their infinite counterparts were obtained. The specified exact formula contains a defect function, which arguments are two similarity parameters: the fractional part of the wave number and the phase value at the leading edge. The defect function is defined only for periodic relief structures, having infinite analogues. Those, where the defect function identically equals zero are called special, and all the rest are usual. The defect function of usual periodic relief structures becomes zero for integer values of the wave number. It can differ from zero only for fractional values of the wave number. The drag wave force of special relief structures is directly proportional to their length. For all the other planar relief structures, this rule may not be applied. The uniqueness of the special planar relief structures is stems from the fact that they have a saw-tooth profile, in which all the vertices of the teeth have the same obtuse angle, which bisector is parallel to the axis. The presence of the abovementioned properties in the special relief structures make them promising candidates for the role of standards used during calibration tests of various installations. If the calibrated planar attachments have special relief structures, then the following advantages will be achieved. Firstly, the technology of special planar relief structures manufacturing is the simplest and virtually insensitive to defects of its practical realization. Secondly, using the same reference attachment with special planar relief structures, and successively cutting off from it by parallel forming bands, makes it possible to perform a precision calibration for a specified range of wave drag. The use of reference planar attachments with special relief structures can increase the accuracy of various installations, and, at the same time, reduce the amount and cost of testing carried out during calibrations. | ||
Kurmazenko E. A., Kochetkov A. A., Proshkin V. Y., Kiryushin O. V., Pushkar' O. D. Selection principles of prospective technologies for life support system of interplanetary manned spacecraft. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/cf0/kurmazenko_kochetkov_proshkin_kiryushin_pushkar_rus.pdf Solution of certain partial problems of ensuring the crew life and activities cannot be regarded as a process of creation of an interplanetary manned vehicle ecological-engineering system development. Such system is designed for long-term manned missions to the planets of the Solar system, in which rather complex interaction of separate elements and products serve as initial materials to ensure functioning of the other in abiotic part of the of ecological-engineering system — integrated life-support system. The determinants of the of integrated life-support system development are space mission program, the type of interplanetary manned vehicle, characteristics of interfaces with onboard systems and its technological structure. The goal of this paper consists in developing selection principles of advanced technologies for integrated life-support system for long-term space missions design, with account for current design constraints. The paper considers natural morphological classification of the technologies based on the following attributing features. These features represent crew metabolism products ‒ a form of energy and primary power services for transformation processes, produced by components of the crew habitat; a special technology and formulated efficiency factors for integrated life-support system technology selection, reflecting its properties as a complex integrated system and features of the considered technologies. The basic principles of technology selection and the list of critical technologies for integrated life-support system of interplanetary manned vehicle developing are formed. | ||
Egorov I. A. Heat flow balance accounting on the aircraft outer surface. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/807/egorov_rus.pdf When flying at high speeds, the surface temperature reaches high values. In this regard, is the role of radiant heat flow in the heat exchange process increased. There is a need for more accurate recording. This article is on the radiant heat flow accounting by numerical integration of the aircraft construction heating process directed. The task is reducing to calculation about the skin one-dimensional heating (along thickness). The heat equation is recorded in the central finite differences form. As a result is create the algebraic equations system. For the boundary points used equations of boundary conditions. For the outer surface used the balance equation of heat flow. The heating process is calculated numerically by the method of numerical integration. The nonlinearity of the dependence of radiant heat flow on the surface temperature is eliminated by using the value of the surface temperature at the previous integration step. Investigated the validity of this approach under various intensity of heat. It is shown that in some cases it is possible to obtain divergent process.The scheme formulated solutions to ensure the sustainability of the process and increase its accuracy. The calculation is performed in the following sequence:
Proposed scheme solution allows to properly take into account radiant heat flux for the intensely hot designs. Conclusions:
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Nesterov M. S., Popelo V. D. Additional characteristic for aircraft infrared visibility normalization. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/d08/nesterov_popelo_rus.pdf The paper introduces the characteristic for quantitative description of infrared (IR) visibility with account for aircraft’s intrinsic equilibrium radiation. The most important state of an aircraft sample’s thermal field, wherein the IR visibility is evaluated, is the state of the intrinsic equilibrium radiation. The aircraft intrinsic equilibrium radiation technical characteristics currently applied for IR evaluation are defined by current observing conditions. The presented work aims at introduction of characteristics, defining the properties of IR visibility in thermal equilibrium with the environment, satisfying the following basic principles: — Measured value must be constant, while changing the conditions of the object observation in a wide range, if the object’s properties as the goal, do not vary in time; — Measured value must be associated by linearly dependence with the parameter of the received reflected or emitted signal; — The value measured in the optical range must be comparable to similar variables used as characteristics of the object in the other electromagnetic spectrum bands. In contrast to currently applied IR visibility figures, the introduced characteristics of effective radiating surface (ERS) does not depend on external observing conditions. The authors considered physical quantities derivations from ERS for the case of linear and distributed objects surveying. Specificity of the introduced characteristics consists in constancy at an object observation conditions variation, as well as existence of linear relationship with a signal value on the radiation receiver (radiant flux density). The presented characteristics allow obtain unambiguous solution of the inverse problem of restoration of a value of an object characteristic according to the measured value of the received signal. | ||
Titov V. A. Peculiarities of Analysis of Space and Rocket Structural Units’ Loading Based on Results of Telemetry Information Processing. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/c58/titov_rus.pdf Algorithms are discussed for loads and stress analysis of space and rocket technology articles’ structural units in conditions when direct measurements of dynamic impacts are absent but there are available readings of recorded structure response parameters which are characteristics of external loading conditions. The problems discussed are divided in three groups and at each of them an impact may be characterized by: — deterministic quasi-static behavior, at that measured kinematic parameters include separating signal components, which characterize displacement of a structure as a solid; — deterministic behavior, at that its temporal characteristics correlate with vibration frequencies of a structural unit; — random behavior distributed over space, and measurement results are structural responses with account of dynamic character at a wide frequency range. General idea of the algorithms consists in determination of external loading through mathematical processing of telemetry data using equations of motion and further integration of these equations with known right-hand member for estimation of internal load factors and mode of deformation at examined structural units. The dynamic models used possess high dimensionality, and force impacts to be restored ‑ long duration. Here high computational recourses are required for operation calculations on decision-making and for statistical computations (with varied structural parameters or external loading characteristics). This defines requirements on computational speed of devising algorithms, which are realized in the program complex developed. The results’ reliability is provided by fulfillment of requirements imposed on high degree of dynamic models’ adequacy to full-scale structures. Quality of inverse problem solution (restored impact) in all cases is estimated by agreement of parameters telemetered (measured in tests) with calculation results on these parameters obtained through the dynamic models with restored force impact. Special attention is paid to identification of dissipative characteristics, which influence significantly on restored time dependences of loading and stress parameters at structural units. The program complex was developed basing on suggested algorithms and it was used for loads analysis of structural units of launch vehicles, International Space Station and at liquid-propellant engine firing tests. | ||
D'yakonov G. A., Nechaev I. L., Semenikhin S. A. Experimental methods of increasing the ablation pulse plasma thrusters specific characteristics. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/eba/dyakonov_nechaev_semenikhin_rus.pdf In this paper, we study the prospects for improving the mass-dimension characteristics of ablative pulsed plasma thrusters (APPT) designed for small spacecraft (SSC) weighing up to 1000 kg. The urgency of this direction development arises from connection with the needing of high-efficiency electric propulsion systems (EPS) of low thrust. It should combining low mass and power consumption with a large resource and total thrust impulse. One of the promising areas is the creation of EPS based on ablative pulse plasma engines (APPT). Prospective increased resource propulsion system should have significant reserves of working fluid and autonomous systems for their storage and supply, through which temporary reconciliation between the energy supply and the mass acceleration into the discharge channel can be. The also necessary parameters are the space propulsion system mass decreasing, the accelerating channel geometry invariance, as well as stability and high specific characteristics during the entire life of the thruster. The most studied version of the APPT is rail-type, with solid dielectric plates. We experimentally investigate its characteristics in this paper. The most important for the EPS practical application are such characteristics as the thrust total impulse P_{Σ}, which determines the SSC characteristic speed, the power consumption N and the EPS total mass, including the mass of the power processing unit (PPU). Currently, the direction emergence problematic assessment was investigated. The possibilities of reducing the mass of the APPT are considered by using new plasma acceleration schemes like channels with an asymmetric discharge. The characteristics of the best pulse thruster flight prototype samples are presented as the result of laboratory experimental testing. The test equipment brief description and the measurement error is giveto assess the error of the results. The main problems that have arisen during the development of new laboratory samples of APPT are considered. In the short term, it is possible to reduce the total mass of the APPT by approximately 15%, using the obtained results. | ||
Gurevich O. S., Golberg F. D., Zuev S. A., Busurin V. I. Compressor mechanization control of gas-turbine engine using his simulation model. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/b62/gurevich_goldberg_zuev_busurin_rus.pdf Basically, the control of modern gas-turbine engines is carried out according to variables which implicitly describe engine basis characteristics, such as a value of thrust, a specific fuel consumption and so on, because their measurability is out of contact. Hardware development of digital automatic control systems (ACS) has broken new ground for an engine control, health monitoring and diagnostic. It has become possible to bring into ACS software (SW) sufficiently detailed simulation model «virtual engine» and calculate unmeasurable engine critical parameters with high fidelity while in engine operation. The article describes new principles of based on such SW control of high-pressure compressor mechanization, which is adaptable to engine operating conditions — closed loop control of guide vanes angle and air bleed valve position according to calculated values of compressor stall margin and efficiency, along with controlling according to excess air ratio in the combustor chamber. A functional block-diagram and heart of software of such control system have been developed in respect to modern turbofan engine with high bypass ratio. As a result of accomplished researches it was shown that using of new control methods may allows: — decrease specific fuel consumption without sacrificing required value of thrust on cruise modes; — decrease up to 10% spent stall margin of HPC during acceleration; — decrease by 5...10% spent stall margin of LPC add stage and decrease by a factor of 1,5...2 maximum values of excess air ratio in order to keep steady combustion in the combustor chamber. | ||
Sha M. ., Agul'nik A. В., Yakovlev A. A. Analysis of mathematical modeling results of subsonic flow inleakage at subsonic profiles. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/111/sha-mingun_agulnik_yakovlev_rus.pdf
Aerodynamic characteristics of blade machines can be determined with high accuracy by experimental studies of models in wind tunnels. However, the cost of such experiments is quite high and, in addition, this method of research does not allow full-scale optimization of all geometric parameters. In this connection, numerical modeling is becoming increasingly important. | ||
Woo S. W. Interplanetary Trajectory Optimization of Spacecraft Driven by Solar Electric Propulsion System with Cluster of Similar Thrusters. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/715/vu-san-vuk_rus.pdf Interplanetary space missions often require large velocity increment leading to necessity to use the main solar electric propulsion systems (SEPS) with high specific impulse to decrease propellant consumption. Electric propulsion system with constant power consumption makes it necessary either excessive increase in the size and mass of the solar arrays or excessive decrease in the consumed power and thrust to provide SEPS operation at the greatest distance from the Sun. Therefore usage of non-adjustable thrusters leads to necessity of using a cluster of the thrusters in the composition of SEPS to permit most efficient power regulation of SEPS using maximum permissible number of operating thrusters depending on the available electric power. The interplanetary trajectory optimization of spacecraft driven by solar electric propulsion system with cluster of similar thrusters is considered. Fixed-time propellant minimization problem is considered. The technique uses Pontryagin maximum principle to reduce the optimal control problem to the boundary value problem and continuation method to reduce the boundary value problem to the initial value problem. Solution of the power-limited trajectory optimization problem is used as initial guess values for initial values of the costate variables. The power-limited trajectory optimization method does not require a user-supplied initial guess. The continuation parameter is introduced into right-hand parts of differential equations of optimal motion to provide the coincidence of these differential equations to the power-limited problem at zero value of the parameter and to the staircase-thrust problem when the parameter equals to one. The smoothed dependencies of the step function of thrust switching and staircase-thrust function are used to provide convergence of the continuation technique. Numerical experiments show good convergence and computational productivity of the presented technique. Presented numerical examples demonstrate importance of consideration the stepped thrust profile at early phases of mission design. | ||
Smorshko I. A. Design-ballistic analysis technique for technical realization of “lunar” takeoff and landing spacecraft. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/208/smorshko_rus.pdf There is a need in the 21st century to implement elaborate methods combining the use of knowledge fr om various areas of science and technology. The article presents the solution technique for design-ballistic analysis problem of technical implementation conditions of “lunar” runway for a takeoff and landing spacecraft. The example of its implementation while special research conducting is given.
As a result of work the equation is obtained:
Equation (1) is basic for this technique development. The developed technique consists of two main parts, namely, ballistic and design. Ballistic calculations allow obtain the relative finite mass of a spacecraft and the relative mass of the consumed fuel by the known values of characteristic speed while realization of this or that branching operation. The problem of characteristic speeds determination is the most complex and depends on concrete mission statement, sel ected flight scheme, landing technique, maneuvers and other dynamic operations. Depending on an input data set and task purposes, equation (1) allows obtain calculated values of such parameters as and different variations of these parameters’ dependences from each other and fr om the values of . To assess the conditions of a spacecraft technical implementation and the maximal frequency rate of the carried-out operations without refueling and other specified conditions, it is necessary to consider the denominator of the equation (1), on account of a condition:
Varying parameters gives the possibility to define the necessary value of the coefficient and the denominator’s solutions region existence in the form of dependence for the concrete number of operations n.
The computational algorithm scheme is shown on the Figure.
Figure. The computational algorithm scheme based on a the design-ballistic analysis technique of technical any takeoff and landing spacecraft implementation conditions (general view)
The first option is not limited to a set of the obtained dependences specified in flowcharts, any variations of quantity (the solution of the equation, sufficient for an opportunity) and the structure of initial parameters are possible and, respectively, at the exit various results can be received (see Figure). The second option represents formation of coefficients possible values area. Depending on the input data the following dependences can be obtained: and depending on the number of operations n. These values can also be set initially, and vary the solution of a problem as well. Moreover, the situation in which , and are known is possible, and then this computation option reduces to finding the limiting value of a number of operations n (Fig.). Earlier published materials contain results of the carried-out design-ballistic analysis on the opportunities of the “lunar” runway creation for a takeoff and landing spacecraft obtained during conducted studies based on the developed technique. The developed design-ballistic analysis technique of conditions of technical implementation “lunar” runway for a takeoff and landing spacecraft is a flexible, efficient and convenient “tool” for conducting studies, that can be applied by specialists of the branch while spacecraft projection and educating students of an appropriate profile at higher education institutions. | ||
Leont'ev V. A., Krymskii V. S., Ignatkin Y. M., Makeev P. V. Computational-experimental studies of tail rotor characteristics at helicopter yawing rotation mode. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/75b/leontev_krymskiy_ignatkin_makeev_rus.pdf In this paper, the computational-experimental studies results of the tail rotor (TR) aerodynamic characteristics at the helicopter yawing rotation mode, at hover are shown. The experimental studies have been carried out by using the experimental model, developed in TsAGI. The experimental model main rotor (MR) diameter D_{MR}=2,5 m, the tail rotor diameter D_{TR}=0,586 m. The computational studies have been carried out using two models: the helicopter mathematical model, developed by TsAGI and the non-linear blade vortical model of a rotor, created by «Helicopter Design» department of MAI. The computational-experimental relationships between the tail rotor thrust coefficient С_{t} and a yaw angular velocity ω_{у} of the helicopter model showed, that for small values of the tail rotor pitch about φ_{TR}=3,8º an increase of ω_{у} resulted in С_{t} increase, however starting from the tail rotor pitch φ_{TR}=9,2º and higher, the coefficient С_{t} decreased. The experimental results confirm the analytical and the mathematical modeling results in the paper [10]. Analysis of the computational-experimental studies results showed that when the angular velocity ω_{у} is growing TR blades are subjected to high Coriolis forces in addition to aerodynamic forces. Coriolis forces have different direction from one side of the TR to the other and therefore, flapping motion of the TR is increasing. By reaching some rotation rate ω_{у}, one side of the TR goes beyond stall, hence the TR thrust ceases to increase. On the other side of the TR blades angles of attack decrease reducing the total TR thrust. The computational relationships С_{t}=f(ω_{у}) and m_{k}=f(ω_{у}) of the TR at the helicopter yawing rotation mode with the MR are in general agreement with the experimental results. They show that the MR vortex wake insignificantly affects on the TR aerodynamic characteristics. | ||
Markin N. N. Angular movement of a passenger aircraft while lift-off from the runway. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/289/markin_rus.pdf The workload of the pilot while takeoff is extremely high. Thus, an aircraft decision speed V1 is defined for particular take-off conditions. After reaching the decision speed, V1, the aircraft keeps on accelerating until the rotation speed, VR, is reached. At this moment, the aircraft nose is lifted. The angular movement of an aircraft on take-off is considered atypical, if a pilot cannot lift the nose wheel and perform the take-off at the estimated speed. Thus, the situation when negative pitching moment is greater than its expected value may create prerequisites for flight accidents. The equal situation may occur when wing’s icing reduces the lift, and the error in determining the aircraft alignment increases the diving moment and other factors. A pilot can use stabilizer to increase the positive pitching moment. The pilot can use stabilizer to increase the positive pitching moment. The angular movement dynamics in this case is considered after the aircraft takeoff to analyze the stalling at a large angle of attacks. The state space system describes the aircraft angular motion and actuators of stabilizer and elevator. The linear quadratic regulators are used for the given two-input linear system. The simulation reveals possibility of stalling at large attack angle with negative pitching moment, if braking force is greater than its expected value. | ||
Petrukhin V. A., Mel'nikov V. E. Pendulum vertical sensor with relay control. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/130/melnikov_petrukhin_rus-.pdf The paper considers the possibilities of stability increasing of a physical of mathematical pendulum to perturbing horizontal accelerations by forming corrective actions on the pendulum from accelerometer and introducing relay control of the compensating signal level. The conducted studies and simulation results authenticate the realizability and high accuracy characteristics of a pendulum vertical reference of such kind. A number of technical applications in the form of control, orientation and navigation problems for aircraft of various classes and purposes can be realized on its basis. Features and benefits of the proposed pendulum vertical reference (PVR) consist in a sufficiently high accuracy with no accumulated errorsin in time, inherent to the vertical channels in SINS, operating in an autonomous mode. This article considers one of the VPR channels with a pendulum and correcting accelerometer to identify the specific and basic features of the VPR. The second channel is implemented in a similar way. In addition to previous studies, to extend the capabilities of the VPR, a relay control mode of the pendulum motion in the vicinity of the vertical is proposed to extend the capabilities of the VPR. | ||
Vavilova N. B., Parusnikov N. A., Filatova G. A. Preparing the navigation system of the underwater vehicle before immersion. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/6ee/vavilova_parusnikov_filatova_rus.pdf In the article the navigation problem for an autonomous underwater vehicle (AUV) is under consideration. In AUV’s navigation the following sensors are usually used: transponders that measure the distance from the AUV to transponders in known locations, velocity sensor, depth sensor, gyroscopic course sensor. A peculiarity of this work consists in the usage of Strapdown Inertial Navigation System (SINS) of medium accuracy together with mentioned above sensors. AUV’s navigation problem is posed as SINS correction problem with aiding measurements. Principal possibilities of this approach are investigated on the basis of the analysis of covariance with experimental data. AUV are used in a wide range of scientific and applied research of ocean, such as a marine geological research, a study of the seafloor, ecological research of water environment. The value of the data provided by the underwater vehicle depends on the accuracy of a navigation system used. That is why the development of high-precision AUV’s navigation system is relevant today. The presented paper differs from previous investigation in this domain by taking SINS of medium accuracy into consideration. Furthermore, data provided by SINS is regarded as the main data. Resulting navigation solution is based on SINS integration with aiding measurements delivered by special sonar beacon with known location (by means of GPS), sensors of velocity and depth. The estimation algorithm is based on technique of Kalman filtering. Mathematical models take into account specific peculiarities of AUV motion (low speed, relatively short distance between a vehicle and a beacon). The two typical types of the AUV’s motion were taken into account. The research method was based on analysis of covariance analysis with implementation of real data. The experimental data was provided by scientific educational center «Underwater robotics», Far Eastern Federal University and IPMT RAS. Marine Autonomous Robotic System «MARK» has two main hardware parts — an autonomous underwater vehicle and an afloat vehicle. An equipment of a shore control center is also included. The afloat vehicle is a mobile beacon with a transponder. The location of the latter is determined by GPS. Vehicles have radio links with hydroacoustic communication system. The presented article studies two representative mechanical trajectories of MARK’s motion. In the first case AUV moves rectilinearly with the constant depth, an afloat vehicle moves along a «zigzag» path with the side 200 m, intersecting the AUV’s trajectory. In the second case AUV moves along a square path clockwise with the side 100 m, an afloat vehicle moves along a square path counterclockwise with the side 200 m. In both cases the direction on the beacon was being changed and as a result the problem of position’s estimation became well-conditioned. Derived results show that the standard deviations of the position’s estimation errors are less than 3 m. It was discovered that navigation solution is not possess the same accuracy. Estimations of the coordinates stabilize after some interval of time, which is depended on the trajectory. Therefore, a preparing method is proposed to achieve equal precision of the estimations on the whole interval of movement. The results of the preliminary analysis that was done give evidence the proposed algorithm can improve the accuracy of aided AUV’s navigation system in several times. | ||
Bogdanov I. V., Velichko A. N. Background and target situation forming method for special optronic systems of missile and space purpose. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/e99/bogdanov_velichko_rus.pdf Solution of the tasks given in the work proposed developing of the background and target situation (BTS) forming method for special optronic systems of missile and space purpose in wide range (from UV to long-wave IR region) that are used in defense and research goals, practical implementation of the method to confirm the correctness of selected schematic circuit, as well. BTS is formed in optronic devices field of view to solve integrated task enabled to conduct different tests types including: reliability testing of single or one of group objects autodetection during background lateral noise simulation of entrance pupil; estimate of characteristics accuracy (for example, constant and random errors of angular deviation measuring); checking of different algorithms of an object under observation selection (spectral, spatial, trajectory and other characteristics). First part of the work analyses current methods and modes of BTS forming. It is examined both national and foreign experience, marked out main advantages and shortcomings of implemented methods, given their schematic circuits, as well. Second part of the work considers realization of BTS forming methods for optronic device as benches on the base of Nudelman Precision Engineering Design Bureau laboratory. It is presented structural assemblies and elements, optical schematic circuits, software for the benches control and testing procedure. The result of the done work is the ultimate method of BTS forming for optronic devices of space and missile purpose that is realized in special benches and enables to reduce optronic devices development expenses due to operability tryout in laboratory environment and to improve the devices quality before space launch. | ||
Smirnov K. K., Sukhov A. G., Tsimbalov A. S. Problems of tests conducting of microcircuits in BGA-type metal-polymeric packages. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/e4f/smirnov_sukhov_tsimbalov_rus.pdf The article focuses on the problems related to a special purpose chipping in metal-polymeric packages with ball leads of the BGA-type (Ball grid array). During microcircuits’ burn-in test and functional control within the specified temperature range a lot of cases of the ball leads separation occurred. This separation led to the need to discard the operable ICs at the final phase of testing. Furthermore, the separation was occurring during the transportation of products. The author analyzed the reasons for strength decline of the leads on various production and testing stages. The method for minimization of the the leads’ strength reduction was worked out. Moreover, the sound arguments are presented in favor of moving the ball-leads formation from the ICs manufacturing to the printed board assembly. The author made the following conclusions:
a) Control of their geometry did not reveal deviations from the initial state; b) Functional control did not reveal changes of electric parameters of IC. The obtained results demonstrate the necessity to include the interim and maybe finishing burn-off operation in the process of the metal-polymeric packages with ball-leads of the BGA type to increase the strength of their attachment. | ||
Aldohina V. N., Demyanov A. V., Gudaev R. A., Byk V. S., Vikulova Y. M. The method of object type recognition in aerospace space on the basis of analysis of radio technical characteristics taking into account the informative character of the signs. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/b98/aldokhina_-demyanov_gudaev_byk_vikulova_rus.pdf The aim of the work is to increase the probability of correct recognition of the type of object in the airspace based on the analysis of the radio technical characteristics of emissions, taking into account the informativeness of the recognition features to a level not lower than required by the regulatory documents. To achieve this goal, we propose a method of recognition using the principle of multichannel with discrete accumulation and using weight coefficients calculated on the basis of the entropy approach. Based on the analysis of the data presented, an increase in the number of characters makes it possible to increase the probability of correct recognition, and the application of weighting coefficients gives, albeit a small, but guaranteed increase in the indicator under consideration. The scientific novelty of the method of recognizing the types of radiating objects on the basis of a set of radio engineering features and weighting coefficients is that it differs from existing ones in that the determination of the type of the radiating object is made on the basis of comparing the additive convolution of particular solutions multiplied by the corresponding weight coefficients reflecting their informativeness with Threshold calculated for the current recognition situation. The theoretical significance of the developed method for recognizing the types of radiating objects on the basis of a set of radio engineering features and weighting coefficients is that it is a development of the theory of pattern recognition and differs from existing ones in that the definition of the type of the observed object is made on the basis of a comparison of the additive convolution of particular solutions multiplied by the corresponding weighted ones Coefficients reflecting their informativeness, with a threshold calculated for the current recognition situation. The practical significance of the method for recognizing the types of radiating objects on the basis of a set of radio technical features and weighting factors is to improve the methodological and algorithmic support of the space monitoring system aimed at providing the required probability of correct recognition. The result of this method implementation will be a decision on the recognition of the type of radiating objects based on the analysis of radio technical information taking into account its informativeness. The considered method of recognition of types of radiating objects allows: — to make the recognition of the types of radiating objects on the basis of radio technical information; — expand the characteristic space used to describe types of recognized radiating objects; — determine the informativeness of the features of the recognition of the types of radiating objects; — minimize the error in recognizing the types of radiating objects; — Reduce the computational cost of conducting recognition of the types of radiating objects. | ||
Boev S. F., Pimenov P. N., Pronin S. A., Shevyrev A. V. The influence of parameters of the ultra-short pulse of electromagnetic radiation on the functioning of radio-electronic devices. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/14b/boev_pimenov_pronin_sheverov_rus.pdf The ultra-short pulsed electromagnetic radiation is relatively new kind of man-made electromagnetic radiation featuring by the pulse duration less than 10 ns. Such radiation forms an obstacle with a spectrum width up to several GHz. It is known that the ultra-short electromagnetic pulse is most dangerous because of its high penetration capability due to continuous filling of the spectrum. Ultra-short electromagnetic pulse (EMP) can have a significant impact on the operation of the modern devices with information pulses durations is comparable with the pulse durations of the EMP. Ultra-short EMP has an impact on the majority of modern wireless broadband data transmission devices, due to interference of overlapping the EMP spectrum of operating frequencies. There are two channels of EMP influence on electronic devices: — Pulse broadband interference — Surge of electromagnetic energy This gives us grounds to consider the potential impact of ultra-short EMP through the foster paths of the devices due to the bandwidth pulse spectrum as well as a direct effect of electromagnetic radiation on hardware (the conductive structure), due to the high concentrated energy of the pulse. Influence on the reception paths of the devices due to the fact that on working frequencies in the reception paths gets part of the generated by EMP broadband interference. The most interesting fact is ultra-short complex sequence pulses with a relatively low pulse repetition frequency package and a short interval between pulses in the package can be regarded as the least expensive energy, but the most dangerous EMP when exposed to radio-electronic devices. The further study of the EMP impact on the radio-electronic devices will identify their vulnerabilities and minimize the impact of EMP. | ||
Surovtsev R. S., Zabolotsky A. M., Gazizov T. R. Pulse signal transmission in the meander line without distortions by near-end crosstalk. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/1e2/surovtsev_zabolotskiy_gazizov_rus.pdf The possibility of pulse signal transmission in a turn of meander line without distortions of its waveform by near-end crosstalk is shown. First of all, the paper presents a brief review of investigations devoted to meander delay lines and approaches to minimization of the signal distortions in these lines. Then the condition of the signal transmission without distortions is formulated and the optimization of cross section parameters and the length of meander line turn is performed in accordance with this condition and for line matching with measuring tract. According to the optimization, a printed circuit board with meander line turn prototypes is produced from the two-side fiberglass FR-4, and the experimental investigations based on combined oscilloscope С9-11 are executed. Finally, the experimental results are presented as an example of one turn with length of 151 mm providing delay of 1 ns. Signals with duration of 440 and 280 ps at half of the maximum amplitude value are accounted. It is shown that waveform of the pulse with duration of 440 ps is affected by near-end crosstalk, which is evident at the signal rise and fall as the positive and negative step with amplitude of 53 mV. If duration of a signal is decreased to 280 ps, the near-end crosstalk pulse with amplitude 52 mV arrives before the rise beginning and after the fall ending and has no impact on its waveform and makes up 10% of the signal amplitude. Thus, the possibility of pulse signal transmission without distortions by near-end crosstalk is experimentally proved. | ||
Samartsev N. S., Kolotilov E. D., Koshelev B. V. Algorithm of data exchange via digital data-link “Ground-to-Board-to-Ground”. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/726/samartsev_kolotilov_koshelev_rus.pdf During last two decades the dramatic growth of air traffic intensity in civil aviation was continuously increasing the workload on the air traffic service (ATS) controllers and the flight crews of the aircraft. This problem was becoming critical and affected the flight safety, especially in terminal airspace. According the CNS/ATM concept improving the efficiency and safety of the modern air traffic management (ATM) system can be achieved through the development and implementation of advanced information technologies and air traffic procedures. One of the most promising technologies recommended by ICAO is the automation of the process of information exchange between aircraft and air traffic control (ATC) centers. For its implementation, modern and prospective flight management systems (FMS) should have a new functional capability such as to support communication via data-link “ground-to-air-to-ground”. As a part of the work on creation of a prospective FMS, an algorithm which allows the generation and processing of data-link messages was developed. The structure of the algorithm was presented in the paper. The concrete algorithm for the flight plan data exchange via the data link “ground-to-air-to-ground” was made in the form of the FMS software module, which is a complete module that allows it to be easily integrated into the software architecture of other FMS. For debugging purposes a simulator of the communication management unit data was developed. The algorithm of a flight plan data exchange via data-link «ground-to-board-to-ground» was successfully tested in the modelling laboratory of MIEA. All work was performed under appropriate standards ARINC 429,ARINC 702A-3, and ARINC 619. | ||
Ivanov V. F., Koshkarov A. S. Noise immunity increase of GLONASS users’ navigation equipment by complexation with inertial navigation sensors. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/054/ivanov_koshkarov_rus.pdf High reliability and adequacy of navigational sightings is the definitive requirement to the aircraft modern navigation complexes. This requirement is especially topical for spacecraft navigation systems in conditions of jamming impact. Experience of navigation equipment operation reveals the presence of a pronounced threshold effect occurring due to implementation of tracking systems for navigation signals processing, i. e. with noise intensity increase the increase of position measurement error is observed, and a certain noise threshold intensity leads to navigation task failure. To enhance the noise tolerance of navigation complexes methods of the user’s navigation equipment complexation with inertial sensors can be used. The proposed method of deep complexation compared to conventional methods allows reduce the probabilities of false captures by tracking meters and signal parameters tracking failure; compensate the object’s dynamics impact on tracking systems; and reduce the tracking rings’ astatism. The pointed above method was used to simulate the navigation complex operation on a software receiver. The ability of using incomplete set of navigation equipment structural elements while realization of deep complexation method is demonstrated. Simulation of navigation complex operation based on deep complexation method revealed the possibility of noise tolerance enhancement to certain types of noise by the stable operation of tracking systems. The proposed complexation method combined with software realization of navigation equipment should increase the efficiency and reliability of navigational sighting in conditions of complex interference situation. | ||
Kozirevskiy V. K., Veselov A. I. Method for reducing computational complexity of face detecting teaching procedure based on Viola-Jones method. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/d25/kozyrevskiy_veselov_rus.pdf The article suggests a method for computational complexity reducing of Viola-Jones face detecting teaching procedure. The reference detector teaching procedure is based on AdaBoost algorithm, representing an iterative procedure of algorithmic composition construction (strong classifier). Each element (weak classifier) of the composition analyzes only one feature of an image. In Viola-Jones method feature is the result of image convolution by some pre-defined filter. A set of possible filters is developed in advance and the best feature in terms of strong classifier’s classification errors decreasing is selected at each learning iteration of AdaBoost. The proposed method is a modification of AdaBoost algorithm where complexity reduction is achieved by adaptive selection of the features to be analyzed. The idea of the modified method is based on the observation that at each iteration of the learning procedure the reference algorithm selects weak classifiers, correcting errors of the previously selected weak classifiers. It means that the weak classifiers with similar performance are unlikely to be selected at the adjacent iterations. Thus the space of the tested weak classifiers can be reduced. The proposed method includes two modifications of the reference algorithm. The first modification consists in a feature pre-analysis operation which is performed to estimate the correlation between the responses of different filters. This stage is performed before the reference AdaBoost algorithm is started. In the process of teaching, only the features with low correlation can be analyzed at the adjacent iteration, thus reducing the number of weak classifiers to be evaluated for boosting the final strong classifier. Practical relevance: the proposed algorithm reduces the computational complexity of Viola-Jones face detector teaching, which is an open issue in computer-vision-related systems. | ||
Kyi M. H., Markin L. V. Mutual shading computation of spacecraft solar antennas. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/083/kui-min-khan_markin_rus.pdf The goal of the study is geometric modeling of solar batteries illumination process onboard a spacecraft or while their location on the surface (on Earth, or, for ex-ample, in lunar settlements). With a specified geometry of their location, the issues of their effective area are studied herewith with account for their mutual shading by each other, as well as by other foreign objects. Solution of these issues should form the basis of software and mathematical sup-port development for solar batteries and concentrators placement and orientation automation on both the ground surface and onboard a spacecraft. The goal of the study consists in effectiveness evaluation of solar batteries layout both among themselves and with other objects, such as a space station hull. This article describes both physical and mathematical statement of the optimization problem on solar batteries placement either in space, or on Earth. It demonstrates that in mathematical statement this problem is considered as an optimization problem of mathematical programming aimed at maximally effective utilization of these high-tech energy sources for both space orbital stations and space settlements. The solution method of this problem is geometric modeling of space station and solar batteries with a certain orientation. The receptor geometric models, discretizing both batteries location area and a space station itself were used as a modeling method. Using C# the software complex allowing solar concentrators’ effective area modeling was developed based on the developed receptor geometric model. The graphic shell was developed herewith, allowing display numerical values of the obtained results. When the software complex is operating after the station and batteries geometry loading in parametric form, geometric model is converted to matrix form, and layer by layer sections’ scanning starts. In each layer of the 3D matrix a 2D matrix is formed, presenting a kind of a 3D matrix slice through a specified distance. Current solar batteries slices’ areas and effective (accumulated) area of a space station’s hull sections are calculated in each section (slice) of receptor matrix. This accumulated area is the spacecraft solar batteries’ effective working area of a specified geometry and sun orientation with account for all kinds of solar batteries’ geometry. The authors developed also a method allowing converting geometry models of the studied objects, developed with any geometry modeling system, such as Solid Works, into receptor models, used for computation operations. The developed mathematical support and software allow evaluating the solar batteries’ effective area at spacecraft specified design parameters and its solar energy flow direction orientation. Simulation procedure allowing optimize the spacecraft solar batteries’ design and geometry parameters among permissible constructive solutions based on the described above receptor model is outlined either. The application area of the obtained results is the design automation of spacecraft and geo-electric power stations located on Earth, or in space colonies. | ||
Lisov A. A., Chernova T. A., Gorbunov M. S. Defining parameters of differential equation of electric motor rotor mechanical rotation mathematical model while its' switching off. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/521/lisov_chernova_gorbunov_rus.pdf The presented work discussed the problems of modeling and mathematical methods for diagnosing the degradation wear of an electric motor in case of bearing unit destruction ‒ one of the most drasic failures. The investigations were carried out on the example of an induction motor with a «squirrel-cage» type rotor widely used in industry and for home appliances. For the degradation wear modeling, the mode of motor switch off from the network, the so-called «run-out» mode was sel ected. As a rule, the run-out mode is considered as the final one in the electric motor work cycle, and is not given due attention. It turned out that this mode presents a source of important information, which implementation makes possible to make judgement on the status of electric motor, its wear, operational safety and the residual resource. This processes occurring in the electric motor is modeling as a second-order link has been carried out. The mechanical rotation of the rotor in the run-out mode is described by an ordinary homogeneous differential equation of the second order with constant coefficients. Parameters of the differential equation, i. e. its coefficients, reflect physical and mechanical properties of the electric motor: its geometry, material properties, etc. The authors proposed to determine the state parameters of the electric motor differential equation fr om the known empirical function of its rotor rotational speed damping, registered in each cycle of its switching off. The paper presents the algorithm of mathematical approximation of the rotor damping rate empirical function by an analytic function with the required levels of accuracy and further determination of the corresponding differential equation parameters. Moreover, the distortion of the rotor rotational speed damping function suggests mathematical methods for diagnosing the degradation wear of the electric motor elements, mainly wear of its bearing assembly. With the degradation of bearings, with embrittlement, dying of metal surfaces with small particles, the moment of resistance of their rotating parts increases substantially. In the run-out mode, the braking torque is increased in the bearings, the stopping time is shortened. Thus, if in the run-out mode the initial speed is less than the passport speed and the braking time is shortened ‒ the degradation processes begin in the bearings. The mechanical time constant T_{M} of the rotor shaft braking function is the characteristic parameter of the degradation processes in bearings. These features can be obtained with the simplest measuring instruments (voltmeter, stopwatch and tachometer) without planning and implementing special experiments, but directly during lectric motor operation. | ||
Gavva L. M. Strain-stress parametric analysis of structurally anisotropic panels of composite materials with account for manufacturing technology in MALAB. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/dee/gavva_rus.pdf The paper discusses the stress-strain state of flat rectangular laminated panel from composite materials, which casing is eccentrically supported by the longitudinal-transverse stiffening set. The panel is subjected to arbitrary distributed transverse load per unit area in the stationary temperature field. Boundary conditions on the contour are assumed of quite general type. The following technological factors occurring during the composites manufacturing herein should be taken into consideration: residual thermal stresses arising during cooling after hardening, and pre-stressed tension in reinforcing fibers. Schematization of the panel as structurally anisotropic, when thin-walled reinforcing elements are in the complex resistance, was proposed as a design model. Further development of the theory of thin-walled elastic rods, related to the contact problem for the skin and the rib, with the refinement of the above said model reflects the scientific novelty of the research. The problem of determining strain-stress state of structurally anisotropic panels is reduced to the solution of the boundary value problem for equation of the eighth order in the partial derivatives in a rectangular field. The resolved eighth order equation and natural boundary conditions are obtained with Lagrange variation procedure. The solution in closed form is constructed by unitary trigonometric series for the particular case of conformable boundary conditions on two opposite sides, and by the method of uniform solutions for arbitrary non-conformable boundary conditions at the contour. We examine all possible variants of the boundary edges restrictions in relation to the connecting plane problem and the bending one. Computer software package has been developed in MATLAB for multi-criterion optimization for the design of structurally anisotropic composite panels of FA. Since the solution obtained by exact analytical methods, the calculation time was minimized, that is of interest from the viewpoint of practical design using parametric analysis. The results of the stress analysis calculations offer the possibility for reducing and optimization of the aircraft elements’ weight characteristics. | ||
Rybin V. V., Tsvetaev V. E. Simulation of fractional aircraft control systems by spectral method in Faber-Schauder function system. Trudy MAI, 2017, no 93, http://mai.ru//upload/iblock/627/rybin_tsvetaev_rus.pdf Today a variety of Computer Mathematics Systems (CMS) and expansion packs are applied for the spectral method of non-stationary control systems computer simulation. Modern technologies associated with fractal approach in different applied areas, and in radio engineering, radiodetection and theory of dynamic systems in particular, produce new element base, where mathematical models contain fractional integrating and derivative operators. For example, control systems with PID control realize control laws, increasing processing speed and stability margin compared to the similar systems realizing classical control laws. Technical implementation of such derivatives and integrals can be realized with several methods: by Gruenwald’s approximate dependencies, or continued fractions, or Fourier transform and spectral transform. Spectral method is already propagated to control systems for models containing fractional integrating and derivative components, and the expansion packs MLSY_SM, Spektr_SM+Simulink+Matlab, Spektr_SM+VisSim+Mathcad CMS have been modified for such systems’ simulation. This software commplex does not contain program packs in the Faber-Schauder function system. The presented paper considers the development of the MLSY_SM SCM Mathcad expansion pack for non-stationary uninterrupted non-stationary control systems with integer number and fractional order spectral method in the Faber-Schauder functions system analysis. Derivation of spectral algorithms with fractional integrating and derivative components of an arbitrary order and of some other spectral characteristics is based on using a symbolic processor of Computer Mathematics Systems Mathcad. Software implementation of the expansion pack MLSY_SM_SH+Mathcad contains software modulus developed using the derived symbolic algorithms. The structure of the pack and its program modules calls are described in Appendix. The expansion pack itself is used for analyzing and parametric synthesizing of the control system for homing missile. Mathematical model of the missile uses a target coordinator (mounted on a gyro-platform) for measuring the sight line rotational speed. Differential equation, describing the target coordinator, contains a fractional order derivative. As a result of the performed work the expansion pack MLSY_SM_SH of Computer Mathematics Systems Mathcad applied for investigation on a stochastic model homing system which uses a fractional target seeker was developed. The dependence of the root mean missing value from differential operator fractional order of target coordinator and navigation constant of command generation block was studied. Optimal values of a fractional parameter and navigation constants were selected. A comparative analysis of homing missile system’s classical and fractional models was carried out. | ||
Krioukov V. G., Abdullin A. L., Demin A. V., Safiullin I. I. Comparison of explicit and implicit difference schemes of calculations for chemical non-equilibrium processes in nozzles. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/aa8/kryukov_abdullin_demin_safiullin_rus.pdf The calculation of chemically non-equilibrium flows in the nozzles of rocket engines is normally performed using numerical implicit schemes (due to the stiffness of chemical kinetics equations). But the progress in developing of the stable explicit methods creates the possibility to use these simple methods instead of the implicit schemes. In this study, we introduce a calculating method of potential number of integration steps for explicit schemes, and their effectiveness is evaluated. The method includes: -calculation of a chemically non-equilibrium flow along the nozzle length using the implicit scheme; -parallel determination of the Jacobi matrix eigenvalues; -calculation of the number of potential steps for the explicit integration scheme based on the stability bound. The calculation of flows was carried out within the framework of the inverse nozzle problem, using the implicitly differential scheme of Pirumov U. G. Numerical research was carried out for the combustion products: - liquid propellants (O_{2} + kerosene; N_{2}O_{4} + C_{2}H_{8}N_{2}) for Laval nozzles at: excess oxidant ratio; pressure P_{oc} = 20…100 atm; minimum radius r_{m} = 0.006…0.06 m and geometric expansion f_{a} = 53.0; - solid propellants (metalized fuel - C_{10.8760}H_{46.546}O_{25.806}AL_{9.665}CL_{1.517}N_{6.781}; nitrocellulose fuel - C_{23.498}H_{30.259}O_{34.190}N_{10.011}) for Laval nozzles at pressure P_{oc} = 20…70 atm; minimum radius r_{m} = 0.005…0.05 m and geometric expansion f_{a} = 33.9. The number of steps of the explicit scheme (K_{1}) was calculated for the Runge-Kutta method of the 4^{th }order. For the reactive media of liquid propellants, a huge number of potential steps (К_{1} ≈ 10^{9}) were obtained at high P_{oc} and r_{m} values. However, with a decrease of the P_{oc} and r_{m} parameters, K_{1} also decreased (to about К_{1} ≈ 10^{7}). In the subsonic part of the nozzle, the K_{1} values were approximately 10 times higher than in the supersonic part. For the reactive media of solid propellants, the results show the same trend, but at a lower level of K_{1} values, especially in the case of nitrocellulose fuel, when max (K_{1}) ≈ 10^{6}. | ||
Aleroeva H. T. Fractional calculus and small angle motions for mechanical systems. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/5cd/aleroeva_rus.pdf Many problems of mechanics and mathematical physics associated with perturbation of normal operators with discrete spectrum, reduced to consideration in Hilbert space of a compact operator , which called for a compact as a weak perturbation or as operator of a Keldysh type. In present paper we consider operators of Keldysh type, associated with boundary value problems for differential equations of second order with fractional derivatives in lower terms. Such problems simulate various physical processes. In particular, the oscillations of a string in viscous media, changes of deformable and strength characteristics of polymer concrete during the loading and etc. Since, considered boundary value problems simulate the oscillations of physical systems, then those problems shall to have a basic oscillational properties. In case when fractional derivatives have order less than 1, such oscillational properties are well-known. In given paper, this properties were proved for order , and there is shown, that mechanical systems, which are described by differential equations of second order with fractional derivative in lower term, are very sensitive to changes of fractional damping order. For example, if we consider a fractional damped van der Pol equation then periodic, quasi-periodic and chaotic motions existed, when the order of fractional damping is less than 1. When the order of fractional damping is , then there are chaotic motions only. This partly explains why oscillational properties (all eigenvalues are primary, and main tone has no nodes), obtained for fractional derivative order is less than 1, not available for fractional derivative order more than 1 but less than 2. In addition, in paper was shown, that operator, generated by the differential expression of second order with fractional derivatives in lower terms and boundary conditions of Sturm-Liouville type, is an Keldysh’s operator. From this, in particular, follows the completeness of a system of eigenfunctions and associated functions for this operator. | ||
Aslanov V. S., Pikalov R. S. Rendezvous the space debris and the space tug using tether. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/b6e/aslanov_pikalov_rus.pdf The problem of space debris it is one of the most important problems of modern astronautics. According to the forecast made by Donald J. Kessler, the space debris can put an end to further space exploration. One of the solution its problem are so-called the active debris removal systems. The essence of this concept is the use of the special space tugs, which carry out the capture of the large space debris objects and their leading away from the orbit. This work focuses on the stage of pulling the space debris by the tug. The main particularity of this paper is to that the rendezvous of the tug and the space debris is done by controlling the length of the tether according to a prescribed law. A mathematical model describing the spatial motion of the tug — space debris system was developed. The tug and the space debris are considered as material points, which connected by a viscoelastic tether. Internal interaction of the tug and the space debris is determined by the viscoelastic force of the tether. The tug is under constant thrust. Motion occurs in the gravitational field of the Earth. The linearized equations of motion was derived. The tether length control law for the rendezvous of the space debris and the tug by means of the viscoelastic tether is proposed. An analytic expression for the frequency oscillations of the tether was obtained. A series of numerical simulations was performed to study the dynamics of the system at the time of the maneuver rendezvous. The simulations are run for 50 seconds with the tug thrust constantly on and without any active control system. The initial altitude is set to be 800 km and the initial velocities of the spacecraft are equal and in accordance to a circular orbit. The Runge-Kutta method is used to propagate the differential equations. Results show that at the end of the maneuver rendezvous in the tether, there are high-frequency oscillations and their frequency increases. That confirmed our analytical expression for the frequency of oscillations of the tether. Influence of the viscoelastic properties of the tether on the dynamics of the system was studied. It is shown that higher stiffness for the tether is better for implementation safety rendezvous of the tug and the space debris. The results of the calculations show that the practical implementation of the rendezvous of the tug and the space debris is possible, but requires additional measures to damping of the oscillations. The obtained results can be applied to study the properties and possible configurations of the active debris removal system, as well as applications for the tasks of implement rendezvous of two bodies using tether. In future research on the subject we should find ways to reduce the oscillation of the tether and verify the dynamics with regard to the consideration of the tug and the space debris as solids bodies. | ||
Popov V. V., Sorokin F. D., Ivannikov V. V. A flexible rod finite element with separate storage of cumulated and extra rotations for large displacements of aircraft structural parts modeling. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/11b/popov_sorokin_ivannikov_rus.pdf A great number of aircrafts parts, modeled numerically, can be treated as a flexible rod, which exhibits large displacements and rotations, but which strains remain small. Spars wing panels, fuselage stringers, screw blades are among these parts. The paper presents derivation of tangent stiffness matrix and deformation loads vector of a geometrically nonlinear flexible rod finite element with large rotations and small increments stored separately. The tangent stiffness matrix and the deformation loads vector are both written in the closed forms and can be programmed relatively easily. The element is derived with conventional finite rotations theory, based on the Euler vector and rotation tensor. Following the Updated Lagrangian formulation, the element rotations are decomposed into to the accumulated part and the small incremental one. This approach allows avoid possible singularities and reach rotation angle magnitudes as large as 2p and even more. The proposed algorithms for the stiffness matrix and deformation loads vector computation are verified by some classical benchmarks. The thorough comparison of the obtained numerical results with existing publications, presenting alternative nonlinear beam formulations, reveals the high accuracy and numerical stability of the developed finite element. It is worth noting, that in the majority of works in this area the authors derive their nonlinear beam models departing from general expressions of the elasticity theory, which are subjected to certain assumptions regarding the dimensions and kinematics of the analyzed object. Such approach though being general (can be applied not only to beams), suffers from excessive complexity for one’s understanding and can hardly be implemented straightforwardly. In the current contribution an alternative paradigm is proposed: the finite element is constructed on the basis of a well-known linear ancestor, which operates with simple strength of materials hypotheses. The classical beam stiffness matrix is wrapped by specific mathematics responsible for the proper description of large rotations and displacements. In this aspect, the developed finite element reminds the corotational FEA concept, described in [28]. Another important advantage of the presented nonlinear beam formulation is the symmetry of its tangent matrix, which is particularly important for numerical implementation, since it permits the more efficient linear equations solvers to be invoked and significantly improves convergence of Newton-Raphson iterations [29]. Not all the geometrically nonlinear beam models (see, for instance, [30]) possess this property. | ||
Krivoruchko D. D., Skrylev A. V., Skorokhod E. P. Excited state population density and spontaneous emission probabilities ХеI plasma of Hall Thruster. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/f77/krivoruchko_skrylev_skorokhod_rus.pdf In the bginning of the paper a low-temperature xenon plasma of Hall Thruster (HT) was investigated by spectroscopic measurements in the 250‒1100 nm range. More than 50 xenon atoms (Xe I) transitions were explored. A measure light power emitted by the plume at optical range was found to be about 0,5 W. The spontaneous emission probabilities (Einstein coefficients) for xenon atom were calculated at the Coulomb approximation (~800 transitions). The obtained results were compared with the results of other authors. By analysis the Hall thruster spectrum Xe I excited state concentrations were identified for 25 terms use getting Einstein coefficients. According to Maxwell’s electrons and Boltzmann distribution the value of excited state concentrations as a function of their energy is a line with line inclination equal to , where – ionization potential from ground state. However, the obtained excited state distribution is poorly approximated by linear dependence and more resembling «swarm» distribution. Measured spectral lines intensities have little differences for each location of collection optics. That could be conditional on heterogeneity of HT plume. However, the mode of the excited state population density persist. That gives evidence of plasma beyond the thruster exit plane common character and unfitness local thermodynamic equilibrium or Coronal model for describe HT plume plasma. In other words, one needs multilevel kinetic model allowing calculate excited state population density which agrees with experimental results for identification electron and nuclear temperature and concentrations. | ||
Nazyrova R. R. Variational calculus as a foundation of medium flow with allowance for real gases state equation. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/824/nazyrova_rus.pdf The modern phase of competitive liquid-propellant engines design is based on employing various mathematical models, including the knowledge of both fluid mechanics and thermochemistry. Mathematical models provide a number of possibilities to study both the most idealized processes and of the special phenomenons, such as the intermolecular reaction of substances, by the equation for real gas state process. Well-known works on the studies of fluid by real gas are based on the accentuate of the amount of virial coefficients in the equation. The presented work is dedicated both to define the each mathematical model as an element of variational calculus tasks class, and to explore mathematical models to find the identical to the initial theories confirmations. The formal expression for the chemical potentials correlation for any substance of the thermodynamic system, described by the equation of the ideal gas state and by the equation of the real gas state, has the integral form. Thus, the mathematical model for any equilibrium state is the task of the variational calculus. Special mathematical technologies (the equivalent transformation, structuring, averaging of integrals) define the task or the subtask of models as the element of classes for the linear or the convex programming. Thus, there is compared to the correct technology of calculations, describing criteria of the identical with model and the acceptable precision of the solution, for the mathematical model of any equilibrium state. The results of mathematical calculations confirm the efficiency of technologies and present the variations of fundamental properties of fluid mechanics. | ||
Polonik E. N., Surenskiy E. A., Fedotov A. A. Automation of airframe with geometrical stress concentrators fatigue life calculation . Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/0b7/polonik_surenskiy_fedotov_rus.pdf Description of SNCalculator software for fatigue life calculation for aviation structures with geometric stress concentrators is given in this paper. SNCalculator is integrated in engineering analysis program Femap. This feature helps to increase automation of fatigue life calculation. Material constants, stress history mask, parameters of calculation theories and mechanical stress level are initial calculation data. Stress data are automatically loaded from Femap model for which static analysis was accomplished. Libraries allow re-use of materials and stress history mask. SNCalculator has post-processing features such as: save results, export results to Excel spreadsheet, export results to Femap FEM, stress cyclogram viewer. Fatigue life calculations algorithm is based on three most widely spread in aviation branch methods: “quality” of construction (developed by Loim V.B.), similarity theory (developed by Kogaev V.P.) and fatigue rating theory (developed by Strigius V.E.). The first two methods are using conception of effective stress concentration coefficient. First method use “quality” as a parameter, which is identified by experimental data and exploitation of analogous structures data. Effective stress concentration coefficient in second method is calculated by Kogaev’s theory of similarity. Third method uses fatigue rating which defined as maximal normal stress of zero-to-tension cycle for which fatigue life is equal 10^{5} cycles with 50% probability with reliability level equal 0,5. Main steps of above mentioned methods are described. Scheme of algorithm of fatigue life calculation realized by SNCalculator is given. | ||
Averyanov I. O., Suleymanov T. S., Tarakanov P. V. General method developing for analysis of soft landing system with air dampers. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/60e/averyanov_suleymanov_tarakanov_rus.pdf The principle structure component of any soft landing system with air dampers is shell with a gas inside it. Behavior of such shell component during the landing defines the safety of the landing object. Area landing relief, weather, soil elasticity etc. defines the conditions of landing. Thereby, the deformation of the landing system every damper could be unique. However, different approaches are developed by other engineers and scientists, and the most popular — numerical methods to develop in LS-DYNA. The main idea is to develop a mathematical model to estimate the behavior of the dampers under loading and also take into consideration elasticity of soil and cargo. Herewith, an interaction between inside and outside gas with shell is included into consideration. The proposed mathematical model is developed using combination of finite element and finite volume methods. Besides, the developed model uses an Arbitrary Lagrangian Eulerian (ALE) approach. Such mathematical model has to be verified. Therefore we solved different problems using this model and compared them with well-known analytical solutions. The first problem is to define a behavior of a closed cylindrical shell container. The air fills the inside volume of the container and the outside one. The inside and outside pressures differ from each other. The shell is considered as elastic and is loaded by the other body with various initial velocities. Furthermore, all bodies are in the gravity field. We obtained results by means of the developed analytical approach and ALE approach. These results show a satisfactorily difference. Then we considered the problem of air flux through the perforation in the air damper during the landing. It helps us to define the influence of the outside air volume on the flux from the damper in case of numerical approach. We also used ALE approach to simulate the deformation of the two air dampers with perforations during the landing. The influence of the considered dampers on each other is presented. Hereby, verification of the developing mathematical model to analyze the soft landing system with air dampers shown good convergence with analytical solutions. Then we will try to solve more sophisticated problems and compare the results with appropriate experimental data. | ||
Golovkin M. A., Golovkina E. V., Gorban V. P. Flow structures near the models of helicopter configurations. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/4b6/golovkin_golovkina_gorban_rus.pdf Flow patterns obtained in water tunnel are presented for helicopter models and their components. Flow visualization was performed using the method of dyed jets. A detailed description is given for the models in which the jet blowing was realized. Visualization of Ka-50 glider model has shown that with decreasing the angle of attack the rearrangement of limit streamlines occurs in nose fuselage so that at α = −10^{о} they are drawn in the underwing area. At α = −10^{о} the vortex cores are generated initiating from the nose section then following under fuselage and along it to the area of horizontal tail. During slip these vortex cores become greatly distorted that may have a significant influence on horizontal tail operation. Investigations of flow structure in the vicinity of Ka-50 glider model with backswept wing has shown that trailing-edge vortices running from tip to root wing sections and further along the aft fuselage to stabilizer area are clearly visualized on this model. In the presence of slip the said vortex structures of the model become visually distorted that may have a significant influence on its longitudinal static stability. Investigations on Mi-26 helicopter model with main rotor simulation has shown that even in the absence of slip (β=0) the flow over the right and the left side of fuselage is essentially asymmetric due to the impact of rotating rotor. On the right side behind the pylon the area of disturbed flow generated by the main rotor disturbances is formed. This is confirmed by comparison with the flow pattern in the right-side view with inoperative rotor. Then this area drifts downstream towards horizontal tail. The flow over the left side of fuselage is much smoother. Only some of pylon disturbances reach the area of tail boom and loading ramp joining. Flow patterns obtained at negative and positive slip of this model are also presented in the paper. The paper presents the results of the investigation of the cylinder model with controlled circulation using a specially contoured slotted nozzle. Visualization was performed in the water tunnel and weight tests were carried out in the wind tunnel. The azimuthal position y of the slotted nozzle determined in reference to the direction of the incoming flow velocity vector and the jet pulse coefficient с_{μ} varied over a wide range. Tests showed that in the region of 100° ≤ Ψ ≤ 135° in lift coefficient and drag increment dependencies on ψ there appeared discontinuities and ambiguity characteristic of hysteresis effects indicating the presence of two possible flow regimes. At small values of c_{μ}_{ }separation occurs above the slotted nozzle, the lifting force increment is caused by air suction from separation zone near the cylinder and by reactive force of the jet. With increasing c_{μ} the boundary layer is attached by the shock, the lift increases drastically, the flow over the upper part of the cylinder is without separation. Investigations of Ka-60 helicopter model in water tunnel with simulation of jet blowing from the slotted and jet nozzles, as well as the air intakes operation have shown the following. The air intakes take water from behind the rotor hub allowing for elimination of separation area behind it that causes the essential part of parasitic drag of helicopter body. The unseparated flow over the tail boom in the vicinity of the slotted nozzle is clearly seen that induces a side force compensating a considerable part of rotor reaction torque. Flow patterns near Yak-24 tandem-rotor helicopter model are also presented in the paper. Visualization of tip vortices shedding from the aft rotor is especially clear. At fixed rotation frequency of rotors the spacing between these cycloid vortices increases substantially with increasing the incoming flow velocity. It is noted that flow visualization in low-speed water tunnel is a highly effective and low-cost technique to reveal characteristic features of the flow over aircraft models in addition to wind-tunnel investigations. | ||
Konyukhov I. K. Compact lift systems of subsonic small-size unmanned aerial vehicles. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/53b/konyukhov_rus.pdf The paper presents the comparison of various types of aerodynamic characteristics of compact wing types using computer simulation. This problem was solved in three-dimensional statement given viscosity and compressibility. the author studied three types of grid wing; four types of contour wing, such as biplane cellule, which lifting surfaces were joined by vertical wing-tip pylons; and triplane cellule with vertical wing-tip pylons. The purpose of this research consists in checking appropriateness of using grid wings with planar airfoil as lifting and control surfaces for small-size subsonic unmanned aerial vehicles, compared with contour wings with convex airfoil. The sturies revealed that grid wings at subsonic speed have a great value of drag coefficient and very low value of lift-to-drag ratio. These parameters can be slightly improved by plane edges revision. The advantage of grid wings with planar airfoils is the ability to operate at very high angles of attack and a smooth nature of flow separation. Reducing the number of internal surfaces significantly reduces the drag coefficient, but lift coefficient reduces either (though not so much). We got in the limit the contour wing with planar airfoils of lift surfaces. It has rather high lift-to-drag ratio, but low lift coefficient. It may be increased by replacing planar airfoils by thick convex airfoils. Simulations have shown that at subsonic speed lift-to-drag ratio of the contour wing is higher than that of a grid wing by several times. Maximum lift coefficients of both types are approximately equal. This allows conclude that under the condition of solving problems of strength and rigidity, the contoured wing is more promising than the grid wing for most types of compact unmanned subsonic aircraft. | ||
Animitsa V. A., Krymskii V. S., Leont'ev V. A. Tail rotors with various solidity values characteristics in hover mode while helicopter rotation computational studies. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/049/animitsa_krymskiy_leontev_rus.pdf A helicopter uncontrolled left rotation mode (for the main rotor clockwise rotation) is one of the worst modes for the helicopters of classic structure. This phenomenon was repeatedly observed at the stages of a helicopter hovering, take-off and landing, requiring increased values of engines’ apparent power at low flight speeds. The main cause of helicopter’s entering the uncontrolled rotation mode is the main rotor operation special feature, associated, in the first place, with the flow induced by the main rotor impact on the tail rotor under a certain air speed direction [1]. There are other contributing factors, which may cause helicopters’ entering uncontrolled rotation mode, such as maximum gross weight; high ambient air temperature; engine low power margin; main rotor reduced rotational speed, blustery wind, landing site blanket created by buildings and constructions capable of generating wind flow vortices, or its directivity and velocity variations. The takeoff or the sideslip landing can be considered as contributing factors as well. At the uncontrolled rotation mode itself, the conditions of tail rotor flow conditions altering. However, this alternation does not facilitate the dangerous mode quitting. Moreover, the angular velocity progressively increases. In the course of this work, the characteristics of various tail rotors have been calculated under rotation conditions with the left angular velocities of ω_{у}=0; 30; 60; 120°/s, when hovering out of air-cushion effect. The computational studies have been carried out by using the helicopter mathematical model, developed in TsAGI [2]. A relationship between the tail rotors relative thrust coefficient and the angular velocities С_{t}/σ(ω_{у}) has been obtained.
The computational results of studies of the tail rotor with the solidity σ = 0,12 are shown in Figure 1. Under minor tail rotor pitch φ_{tr}, the coefficient C_{t}/σ is increasing insignificantly, and the blades rotate under pre-stall mode. When the φ_{tr}_{ }is increasing_{ }up to 21° and more, the coefficient C_{t}/σ is sharply decreasing. The tail rotor thrust is not increasing, but is sharply decreasing.
Figure 1. Relationships С_{t}/σ = f(ω_{у}) for σ = 0,12
The angular velocities ω_{у} influence on the tail rotor operating conditions has been analyzed. The distributions of the lift force coefficients С_{у}
and the tail rotor blade angle of attack α, on the r = 0,75R blade section, vs the blade azimuth and the angular velocity have been obtained. The changes of the tail rotor blade lift force coefficient С_{у} on the φ_{tr }= 25° are shown in Figure 2. The Graph shows, that when the ω_{у} increases, the lift force coefficient С_{у} decreases.
Figure 2. Relationships C_{y }= f (ψ) for σ = 0,12, φtr 25º | ||
Azarov Y. A., Chernovolov R. A. Drained aeroelastic aircraft models. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/45f/azarov_chernovolov_rus.pdf Drained dynamically scaled models have been designed to study aircraft unsteady aerodynamic performance in wind tunnels. Nowadays this kind of experimental research is preferred for future aircraft both flutter and buffeting safety studies, along with verification of CFD methods with allowance for the structural elasticity. While drained dynamically scaled models developing a number of requirements, including geometric, mass, stiffness and dynamic similarity, should be met. Furthermore, additional requirements for safety margins and high fidelity of measurements are implied. In the Laboratory of Dynamic Modeling of the Central Aerohydrodynamic Institute several models have been designed and manufactured: — Drained dynamically scaled model of short-range passenger aircraft wing — Drained reference dynamically scaled model of transport category aircraft wing — Drained dynamically scaled model of short-range passenger aircraft horizontal tail — Drained dynamically scaled model of medium-range passenger aircraft flap The creation of drained dynamically scaled models became possible through the use of advanced polymer composite materials and FDM (Fused Deposition Modeling) additive technologies. Verification of the model geometrical characteristics is carried out on a coordinate measuring machine. The results of this work are as follow:
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Basharov E. A., Vagin A. Y. Analysis of Polymeric Composite Materials application for helicopter airframe design. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/3a2/basharov_vagin_rus.pdf The studies conducted in the 1980s of the 20th century by a number of the US aircraft manufacturers under project administration of U.S. Air Force Materials laboratory, has shown that practical application of polymeric composite materials (PCM) in military airplanes and helicopters design results in not only considerable decrease of their weight and cost, but also in higher survivability, maintainability, many other improvements. In the late 70s of the 20th century the U.S. Government, by request of the Air Force, invested in research work and Advanced Composite Airframe Program (ACAP) to demonstrate helicopter weight and cost reduction potential with maximum wide PСM application in its design. The ACAP program results were extremely successful. S-75 and D-292 demonstrators made clear the advantages of PСM application in the helicopter airframe structure achieved by maximum structure integration and use of large-size three-layered panels with honeycomb core, special shape of external panels to reduce the radar signature, as well as the implementation of the parts highly resistant to battle damages and capable of energy absorption at crash landing. At about the same time, the helicopter development projects known today as Ka-50, Ka-226, Ka-60/62 were in progress in our country. From the very beginning wide application of PCM in the helicopter structure and, first and foremost, in the airframe was the target goal. PCM implementation in the fuselage structure purported weight reduction, labor hours and industrialization cost reduction, as well as lifetime and combat survivability increase, and operational costs reduction. This task was successfully solved. Based on world-wide successful results of PCM implementation in primary and secondary helicopter airframe structures, the 90s of the 20th century marked a consistent trend among all key helicopter manufacturers to extensive PCM application in new helicopter airframes. That is why when the development of Ka60/62 helicopter project was initiated in the late 80s, Mr. S.Mikheev, Kamov Company General Designer, set up the task of extending PCM application in the fuselage design up to 60‒70%. The manufacturing technological problems of large-size integral three-layers panels made from PCM were solved successfully. At the same time the manufacturability and costs analysis of the proposed technical solutions led to refusal of PCM application in the critical parts and assembles of Ka-62 fuselage. Based on the analysis of design and manufacturing experience on helicopter airframe parts made of PCM, the paper offers substantiations and main conclusions on PCM wide-scale implementation in the helicopter design. Advantages and disadvantages of PCM application are demonstrated and main present-day obstacles on the way of wide PCM implementation in Russia in the helicopter design are outlined. Possible ways of their overcoming are suggested as well. | ||
Kychevskii S. V., Gervald A. V., Onyfrienko V. V., Titov Y. P. Air pressure in aircraft pressurized cabin control optimizing method. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/67b/kuchevskiy_gervald_onufrienko_titov_rus.pdf The subject of research is the air pressure regulation system in the aircraft pressurized cabin. The purpose of the work consists in developing a mathematical model of predicting the required air pressure in the aircraft pressurized cabin with a view to predictive actuation of control valves of conditioning and pressure regulation system to prevent accidents. The performed evaluation of air pressure regulation in modern aircraft of the fifth generation pressurized cabin capability revealed that at intensive combat maneuvering mode in vertical plane, and in case of the aircraft cabin decompression at high altitudes, the conventional facilities did not ensure pressure regulation in the cabin according to medical-technical safety requirements for crewmember safety under extreme conditions of high-altitude flight. These modes do not ensure reliable protection of crew members fr om unfavorable factors of high-altitude flight. The evaluation of the technical capabilities of air in the pressurized cabin of modern aircraft 5th generation pressure control systems showed that there are modes of intensive combat maneuvers in the vertical plane, as well as instances of cabin depressurization of the aircraft at high altitudes existing facilities do not provide pressure regulation in the pressurized cabin according to health -technical requirements of crew safety in the extreme conditions of high-altitude flying, thus these modes do not provide reliable protection of the crew from the adverse factors of high altitude flight. The paper proposes the method for air pressure control based on the flight parameters control and computing for the preset time interval the pitch and vertical speed values, depending on the control stick position changes, according to previous calculations our mathematical model shows required pressure in the pressurized cabin and its rate of change. If the pressure in pressurized cabin deviates from the lim it value, the proactive changes in pressure in the pressurized cabin are performed in pre-calculated time interval by affecting air regulator and pressure regulator valves. The paper presents mathematical model of pressure control in the pressurized cabin and the valve control algorithm in the pressure control system. | ||
Schurovskiy Y. M. Gas turbine engine lubrication system mathematical modeling specifics. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/d53/shchurovskiy-_rus.pdf The paper presents the developing principles of dynamic mathematical model of oil systems with electrically driven pumps for gas turbine engines (GTE). The oil system with electrically driven pumps can replace the traditional system with pumps driven by gearbox. The demonstrational oil system model with adjustable electrically driven pumps was developed in the CIAM. Experimental studies of its characteristics on the workbench with the simulator oil chamber GTE demonstrated the complexity of hydro- and gas-dynamic processes occurring in it, and the need to develop dynamic models of such systems. The literature generally discusses the mathematical models for the study of oil systems based on static hydraulic ratios without considering the dynamic characteristics of pipelines, gas content changes over the path of pumping the two-phase mixture, and others. The dynamic mathematical model of the system based on finite element with lumped parameters is designed to sel ect its characteristics and control laws. The finite element describes the part of pneumo-hydraulic circuit of oil system. Gas and hydraulic network system are divided into separate sections of working medium flow (pipelines, etc.), concentrated volumes, pumps, located on sections, are described by quasi-static characteristics. The distributed pressure losses due to friction within the pipeline are focused at the border and summed with the losses on other hydraulic resistances of this section. It is assumed, that the pressure, temperature, mass gas content and thermal characteristics of the working mixture are constant along length of the concentrated section and vary only in time. The volumes of the type of oil cavity, where two-phase medium is formed fr om air and oil, describe the stratified flow of oil-air and air-oil mixtures. The change of thermal and thermodynamic characteristics is calculated in the acoustic volumes, where the two-phase flows merge. Calculation of two-phase mixture movement in the pipelines is made with allowance for its inertia and compressibility. Solution of the system model is carried out in a computer program by direct numerical calculation without iterations (Euler method). Comparison of the calculated and experimental processes in the demonstration lubrication system revealed their good agreement in the area of the 1-st tone oscillations of hydraulic network system 0.2 ... 5 Hz. | ||
Agul'nik A. В., Gusarov S. A., Omar Hewa H. O. Gas-steam turbine cycle basic parameters selection for gas pumping units. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/6d2/agulnik_gusarov_omar_rus.pdf The paper tackles with the issue of a gas turbine and steam-turbine cycles’ basic parameters of a gas turbine installation under development for gas pumping units, based on aircraft jet engine. The goal of this work consists in gas pipelines pumping units’ efficiency increase by utilizing a gas turbine engine high-temperature exhaust heat energy and the realizing a lower-temperature steam cycle. With the combined power plant processes T-S-diagram it was performed the selection of the main parameters of the gas turbine and steam turbine cycles according to the needs of temperature differences. Calculations show that the creation of a combined gas and steam power unit is possible. The initial temperature of the gas turbine cycle should not exceed 1500 ... 1600 K to ensure that the free power turbine will work without blade cooling. Based on a combined power plant processes’ T-S diagram the authors carried out selection of the gas turbine and steam-turbine cycles’ basic parameters with allowance for the temperature difference requirements. The computations demonstrated the possibility of such combined gas turbine installation development. The gas turbine initial temperature herein should not exceed 1500 ... 1600 K to ensure the free power turbine operation without blade cooling. pumping unit based on aircraft jet engine RD-33. Whereby the results demonstrate that the power of such combined plant will be 20 MW (15.5 MW and 4.5 MW) with effective efficiency of 45‒50%. All the above said allows draw a conclusion that gas-turbine installations are prospective for gas pipelines gas-pumping units’ drives and allows reduce of fuel gas consumption for compressor station’ auxiliaries. | ||
Pavlov P. V., Popov F. N. The information-diagnostic system flaw control. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/3b8/pavlov_popov_rus.pdf The work is dedicated to the development of flaw control information diagnostic system, the ability to expand the possibility of non-destructive testing devices which operation is based on optical radiation speckle patterns method. Method of «chessboard» is used as speckle imaging tool. This method allows analyze the dynamics of the parameters changes in a defect by analyzing the changes in the studied surface roughness parameters, as well as to carry out work on determining the depth of defects in the internal structure of composite materials. This method is applied to control the subsurface structure. Its operation principle consists in sensing of the object with increasing laser power. Experimental studies have confirmed the effectiveness of these methods, and proved that the method of «checkerboard» can be used to monitor the cracking and residual lifespan assessment of details, employing the method for determining the internal structure of composite materials, and the depth of the defect in the internal structure of an object. Thus, the introduction of the developed information-diagnostic system will allow for flaw detection of aircraft control units and assemblies at a new technological level. | ||
Kruchinin M. M., Kuzmin D. A. Helicopter chassis drop tests mathematical modeling. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/cbb/kruchinin_kuzmin_rus.pdf Drop tests present a necessary part of a helicopter design and certification. However, man-hours necessary for carrying out these tests are rather labor consuming, and the tests themselves are not safe. Thus, helicopter chassis drop test mathematical model development is considered as a topical task. Drop tests consist in dropping the aircraft landing gear with the reduced weight attached to it from a specified height. this weight is selected according to the norms of safety. The paper considers mathematical modeling of drop testing of the main and front landing gear struts of the Mi-38 helicopter with software packages LMS. Amesim. Imagine. Lab and LMS.Virtual. Lab. The authors describe the methodology and stages of front and main landing gear shock absorbers mathematical models development with the data packs, and the numerical experiment obtained results. The synthesis of shock mathematical models, as a combination of the pneumatic, hydraulic and mechanical systems operation, held in LMS.Amesim. Imagine. Lab package. Validation of models of shock absorbers made by comparing with the received data compression diagram of the manufacturer. Building a model of the landing gear mechanical and mathematical modeling of its contact with the surface of pneumatics was performed in LMS. Virtual. Lab pack. The landing gear drop tests modeling carried out by sharing calculation in packages LMS. Virtual. Lab and LMS. Amesim. Imagine. Lab. The simulation results are compared with manufacturer’s experimental data of field tests. is confirmed The reliability of the used models is confirmed by operational work diagram representing the dependence of force at the point of contact on pneumatic vertical movement of the center of gravity of the dropped cargo at various test conditions. Comparison of the calculated and experimental data demonstrated the possibility of using this method for the preliminary analysis of the permissible loads in the tests for dropping, which provides a significant reduction in the volume of drop tests. The possibilities of further development of the developed method for helicopter landing simulation in various conditions regulated by the rules of safety. | ||
Busurin V. I., Mevedev V. M., Karabitsky A. S. Modular inertial control systems control and diagnostic systems for design features. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/984/busurin_medvedev_karabitskiy_rus.pdf The basis of technical information, measurement and control systems support consists of electronic devices and systems for information communicating, gathering, processing, transmitting and displaying, which, belong to subjects to diagnosis at the stages of development and production. For means of control and most of other types of inertial control system tests, it is generally accepted to implement checkout equipment (CE). Hardware and software of the CE are developed individually for the requirements of inertial control system specific tests. To simplify the design and improve versatility, this paper offers to rethink CE software design methodology, allowing form CE software automatically for control and diagnostics purposes of several similar inertial control systems. This solution will significantly reduce the time and cost of the CE hardware and software parts developing. The software forming is carried out by attaching additional software modules (ASM), responsible for unique to a particular inertial control system (ICS) equipment or functionality, to basic software module (BSM). The developed software remains intact while being used for control and diagnosis of various ICS’s. BSM performs functions such as distributing software threads and their priorities, launch and control of ASM. ASM are developed in conjunction with CE, and possess unique features. Interaction between modules is carried out through the shared memory and communication protocols between modules. Considering the fact that ASM’s are designed to perform specific tasks, such as recording telemetry in the selected format, working with mezzanines boards, or record sensor readings, as well as due to the fact that they are designed as a separate project, the developers unassociated with basic module design can be involved in their creation. Small size and relative simplicity of development of each module significantly accelerates this process. Uniqueness of each CE set of hardware components, such as a set of sensors, opto-boards, interfaces, makes it possible to determine most of required ASM, by self-control using the ICS simulator. Trial ISU run and analysis of incoming telemetry can help to determine additional software modules. | ||
Evdokimchik E. A. Control algorithm to automatic perform the avoidance maneuver from collision with terrain. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/823/evdokimchik_rus.pdf A controlled flight into terrain remains a serious problem for the commercial and military aircraft. It is difficult for a pilot to adequately estimate the degree of maneuverability and safety on a modern maneuverable aircraft. To improve the flight safety applies systems which warns the pilot of the ground proximity and performs an automatic collision avoidance maneuver in case of security threats. The article deals with the control algorithm for performance of the automatic maneuvers intended to avoid collision with the ground. The proposed algorithm is designed for the aircraft with control loops of g-load and roll angle. A collision avoidance maneuver is divided into two phases. The first phase is focused on stopping the descent of the aircraft. The goal of the second phase is the safely transfer control of the aircraft to the pilot. The first phase of maneuver can be performed by using two control strategies. The first control strategy consists of a roll to wings level combined with performing a desired g-load. Desired g-load is negative when roll angle more than the point ahead angle and positive in other case. The point ahead angle depend on the ratio of performances of g-load and roll angle control loops. The recommendation for chose the point ahead angle for a particular aircraft is given. The second control strategy is to perform aerobatic figure, called “overturn”. The control algorithms of vertical flight speed and altitude to execute the second phase of the avoidance maneuver is designed. The logic for perform avoidance maneuver and block diagram of the control algorithm is created. | ||
Il'yasov S. P., Kornilov A. V., Losev V. V. A standby instrument system for a high-maneurability manned aerodynamic aircraft. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/263/ilyasov_kornilov_losev_rus.pdf The paper tackles the issues concerning a process of methods and techniques development, meant for increase the quality factors of the high-maneuverability dual-purpose aircraft avionics through enhancing the technical performance of the standby instrument system. The authors proposed, in particular, to employ an electronic integrated standby instrument system, in which the indigenous compact medium-accuracy sensors are used. The distinctive features of the systems are the data communications between the elements, as well as software and hardware tools based on them. It allows measuring the significant number of an aircraft movement parameters, increasing the accuracy of measurement and enhancing the reliability and usability factors. The results of the semi-scale modeling are given with the use of the real-time telemetry under real flights of the high-maneuverability aircraft, ground-based adjustment and flight tests. | ||
Hein Tay Z. T., Mel'nikov V. E. On the possibility of determination aircraft takeoff weight. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/725/kheyn-tay-zar-tin_melnikov_rus.pdf The exact knowledge of an aircraft take-off weight, including the actual fuel weight on board and center mass is a factor in flight safety and its controllability. Conventional weight measuring systems do not allow for the rapid control of these parameters in real time. The authors consider the possibility of an aircraft take-off weight operational determination while maneuvering along the taxiway to the runway starting area. For this purpose, the taxiway must hold the traceable area equipped with sensor bars, embedded in an underlying surface according to the number of the aircraft’s support landing gears, and electronic component to ensure the operability of the sensors, information processing, and remote transmission to Central office for decision making. The paper justifies the layout of sensor bars, the geometry of the receiving surface, perceiving the pressure force of the aircraft landing gear on the underlying surface, and specifies the requirements to the primary sensors energy characteristics, which converts the pressure force into an electrical signals and their number. Particularly, the longitudinal dimension of the sensor bar must have a phase of whole position of contact patch of wheels on the perceiving surface of the sensor. This allows extracting the additional information useful to diagnose the state of the wheel elements of the landing gear. The main requirements to the primary sensors are high accuracy and versatility. The most promising seems to be the sensors, such as electromechanical transducers, based on amorphous and crystalline quartz with frequency dependent output signal. This can be unified quartz string transducers of forces and deformations. Quartz capacitive transducers can be in conjunction with the quartz crystal oscillators as well. Further, the paper presents the main available characteristics of the sensors, which determine the ultimate load, steepness and temperature error. | ||
Karpunin D. N. Advanced onboard means to confirm the accuracy characteristics of systems for remote sensing of the earth. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/f88/karpunin_rus.pdf The questions of creation of a highly stable promising means to confirm the performance of optoelectronic equipment for remote sensing at the stages of flight test and operation during the active lifetime of the spacecraft, which provide the possibility of high-precision onboard calibration with traceability to national standards. The objects of research are models of onboard black bodies based on phase transitions of high-purity substances and their eutectic compounds, which build to confirm the accuracy characteristics of remote sensing equipment in the infrared spectral range, as well as highly stable detectors that measure external influencing factors around the spacecraft area. Creation of highly stable onboard equipment is based on unique property of substances in the process of phase transitions, as well as a special design for the required characteristics. Theoretical and experimental research, including microgravity, was conducted. As a result, found that the physical principles and design features underlying the work of emitters allow to ensure the traceability of measurement results to national standards, the compensation of the temperature dependence of sensor equipment will provide the reliable data on the measurement object, namely, the state of its own outer atmosphere of the spacecraft. Development of advanced tools onboard calibration confirmation of the accuracy characteristics of remote sensing equipment will deliver the required level of output quality. The results are used to implement the requirements of international and national standards, which are needed to confirm the accuracy characteristics during operation, what is currently not provided with the required metrological characteristics. Creating a promising onboard calibration means for verification accuracy characteristics of remote sensing equipment will ensure the achievement of the required level of quality of the data and improve their competitiveness. | ||
Kolpin M. A., Protsenko P. A., Slashchev A. V. Effectiveness evaluation technique for ground automated control functioning of a spacecraft. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/a38/kolpin_protsenko_slashchev_rus.pdf The absence of common methodological base for functioning efficiency evaluation and capabilities of Ground Automated Control Complex (GACC) makes practically impossible the procedure of scientific study and evaluation of various options for its development and introduction of advanced unified spacecraft management tools. The results of scientific and methodological ground-based activities applicability analysis from the viewpoint of an individual spacecraft GCC evaluation capabilities, revealed the difficulties in estimation GACC overall efficiency. Thus, it becomes urgent to develop alternative approaches to estimating the GACC effectiveness, allowing obtain estimates of GACC’s operating efficiency indicators based on composition, structure and parameters of the Orbital Constellation (OG) of space crafts, as well as the requirements and limitations of spacecraft control technology. Spacecraft GACC functioning efficiency estimation method was designed for this purpose. It allows obtaining rational GACC structures for controlling spacecraft OG and evaluating their implementation effectiveness. The developed method demonstrates several advantages over the existing conventional approach, such as: – The ability to plan collaborative control operations in automatic mode; – The plans obtained using the conventional approach do not always meet the required sequence order of control operations, unlike the plans prepared using the developed method; – Сomputation speed with the proposed method is 1.5 times higher than with the existing approach. The proposed method can be implemented in the following cases: – Computations for spacecraft GACC functioning effectiveness assessing t in various conditions, performed at stages of a long-term and operational planning of its resources employing; – Prospective composition spacecraft GACC evaluation capacity and advanced spacecraft control technology studies; – The study of various kinds of requirements for both in general (GACC) and in particular (spacecraft); – Justification trends in spacecraft GACC development and improvement. | ||
Belozerova I. N., Kudriavtseva N. S. Analysis of ultrasound parameters for a spaceman bone tissue regeneration during long-term space missions. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/09c/belozerova_kudryavtseva_rus.pdf The paper discusses mathematical modeling, analysis and parameters selection of ultrasonic interaction with a spaceman’s injured bone tissue to accelerate its regeneration during long-term missions. The authors developed a mathematical model of ultrasonic interaction with multi-layer system of a biological human tissue based on reflection of the mechanical ultrasonic energy at the boundaries, such as “soft tissue — cortical bone tissue”, “cortical tissue — trabecular bone tissue”, “trabecular bone tissue — bone marrow tissue”. Mechanical ultrasonic elastic stresses of biological cells in the bone tissue such as displacement amplitude (deformation) and shear forces on the cells of cortical bone that stimulate regeneration of the cortical bone tissue without causing cells destruction and cellular organelles were computed. The temperature gradients in the cortical bone were computed to evaluate thermal effects of ultrasound on biological cells. Finally, the recommended parameters of ultrasonic exposure for accelerated regeneration of a spaceman’s cortical bone tissue: intensity of ultrasonic source: I_{0} = 0,05 — 0,1 W/cm^{2}, the oscillation frequency f = 0,02 — 0,1 MHz, the duration of continuous exposure shall not exceed 10 minutes were elaborated. Moreover, the weight of a spacecraft life-support system will not be increased as the ultrasonic device is already a part of the medical and technical equipment onboard the orbital station. The presented study is the first one to offer implementation of ultrasound with the parameters selected to accelerate a spaceman injured bone tissues regeneration during long-term missions. | ||
Suchkov A. V. Simulation of broadside impact on frequency-scan array antennas. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/504/suchkov_rus.pdf Frequency-scan array antennas (FSAA) are widely used in airspace surveillance radars and air traffic-control systems. In most cases, these antennas present a planar equidistant array of linear emitters connected to the traveling wave multichannel power divider (PD). PD is based on couplers, connected in series with sinuous delay line (DL). It is well known that sharp increasing of PD input voltage to standing-wave ratio (VSWR) on the frequency corresponding to beamforming near broadside is a significant disadvantage of such antennas. The reason for this is the in-phase addition of large quantity of even low reflections from periodic discontinuities: couplers and DL bends. This effect, which leads to a significant gain reduction and unacceptable distortions of directional pattern, is called a “broadside impact” in technical literature. Currently, to eliminate the broadside impact, the method, based on integer odd number of quarter-wavelength in DL shift between all of even and odd discontinuities was proposed. This paper presents the simulation results obtained using the algorithm, realized in MathCAD. The algorithm was designed for FSAA PD input VSWR evaluation at a certain reflection level from periodic discontinuities and amplitude-phase distribution (APD) forming in frequency-scan plane. During the simulation it has been established that the aforementioned elimination method have a disadvantage, i. e. occurrence of broadside impact in the lower and upper operating frequency range when wide-angle scanning with pattern at a relative bandwidth of more than a few percent was implemented. Thus, the new method, which was designed for complete elimination of broadside impact, is proposed. It is based on automated iterative search procedure of electrical lines lengths connected between the couplers and DL bends. The iterative convergence condition search procedure is defined by PD input VSWR lowest possible value, which achieved in operating frequency range at a certain reflection level from discontinuities. Reasonability of transition from PD series circuit to series-parallel circuit with wide-angle scanning implementation in a relative bandwidth of more than 5% was analyzed. Thus, the main practical result of research concludes in FSAA broadside impact complete elimination possibility and, respectively, operating frequency range and scanning sector expansion without reducing the antenna gain requirements. | ||
Lobachev N. Y. Non-uniformity (of capacitive type) effect on a waveguide Ka waveband filter frequency response in case of adjustment elements made of conducting material replacement by elements made of dielectric material. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/e55/lobachyev_rus.pdf With reference of constantly growing demand for radar installations of new generation implementation, the issue of meeting the strict requirements to SHF-devices becomes quite topical. Filters play one of the key roles practically in every navigation or communication system. The main functions of the filters consist in ensuring: ‒ pass-band in the specified frequency band; ‒ necessary suppression level; − low level of insertion losses; − specified amplitude-frequency response. The main purpose of the research is consists in comparison of influence of heterogeneity (capaciti character) on filter skirt. Two ways of setting of the waveguide filter has been presented. The presented paper focuses on studying the procedure of waveguide SFR-filter of Ka waveband tuning. The filter key parameters while tuning are as follows: its characteristic conformance to specification requirements and total tuning time, which is especially up-to-date at mass production. To ensure these parameters at conventional tuning metal screws are used. These screws present a non-uniformity (of capacitive type) for cavity links matching adjustment. The presented study suggests innovative solution in this sphere, which consists in metal screws substitution by fluoroplastic ones. It is associated with some key specifics of this material. It is noteworthy that in the framework of this research thermo- and vibro-strength test were carried out. These tests present an important criterion, warranting the features stability of the tuned unit. The assumption that by material substitution we will manage not only cut the time of waveguide filter tuning, but also ensure the more qualitative frequency response were substantiated experimentally. Moreover, while working on this problem the accessory for convenience in this procedure realization was developed. Thus, the presented work presents complex comparison of the obtained parameters, complexity and time component of the two variants of waveguide filters tuning procedure. | ||
Arefiev R. O., Arefieva N. G., Skrypnik O. N. Improvement of air navigation support of the landing phase by optimizing the allocation of pseudolites GLONASS. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/87e/arefev_arefeva_skrypnik_rus.pdf The article is devoted to the problem of the rational quality definition of the GLONASS system pseudo satellites and to the problem of optimization of their location relating to the runway for supplying better accuracy of the aircraft positioning on the final landing stage. The article presents the optimization criterion based on the minimization of the vertical geometrical factor both in a pre-set point and lengthwise the glide path. The difficulty in solving the problem is in a constant change of a geometrical factor due to the satellite moving relating to a user. The problem of optimization has been solved during a period of time which is equal to a period of orbital movement satellites GLONASS frequency with an hour discreteness. In this case we get a set of pseudo satellites locations which are optimal for a certain chosen moment of time. The method of finding the only positioning of pseudo satellites among others offered is based on the creation of the histogram of the latitude and longitude coordinates. To define the optimal pseudo satellites location, certain algorithms are drawn up which are based on the method of a direct search ( by Hook-Jeeves) and a no rigid polygon (by Nelder-Mid). The comparison of results got by both methods proved the adequacy of found solutions. To conduct the research a program complex LabView was created. It has got the module of orbital movement GLONASS imitation which works on the base of the functioning almanac of the system. The data out of this almanac are the characteristics of a nautical session in a set point of any pre-set period of time. And the data out of the optimization module that implements certain algorithms are the coordinates of optimal position pseudolites points. On the bases of the carried research there is a benefit in the average value of geometric factor both lengthwise the glide path and certain points provided in case of the pseudolites optimal position. The Influence of the number of optimal position pseudolites on the vertical geometric factor value in a zone of the airdrome was researched. It was proved that for the vertical geometric factor minimization and the zone increase, within provided minimum value, the use of more than three pseudolites is not rational. | ||
Gogolev A. A. Semi-natural modelling of unmanned aerial vehicles like multicopter. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/19a/gogolev_rus.pdf Rapid development of multicopters became possible due to the popularity of MEMS technologies, brushless engines and high-capacity lithium-polymer batteries. Multicopters are widely used in unprofessional aviamodelling, military and civil tasks because the construction is very easy-to-use. In spite of this multicopters don’t have the ability of windmilling and glide landing therefore multicopter are damaged easily. Semi-natural modelling helps us to reduce risk of damage, decrease time and increase the efficiency of developing UAVs. Semi-natural modelling have the maximum accord with full-size UAV. Semi-natural modelling system of multicopters consists of two parts: modelling system and computing center. Computing center computes math model of multicopter and environment, visualizes the results of math modelling, registers parameters of math model and modelling system. Modelling system controls the multicopter in math model, makes the dynamical similarity of the system, simulates of navigation system, visualizes the environment of modelling. Computing center consists of multicopter math model, environment math model, visualization system, registration system. Modelling system consists of Stewart platform with six degrees of freedom, collimation system, imitator of navigation system (GPS, barometer, compass), quadcopters CPU. Equations of math model compute in Matlab/Simulink system. Model of environment is used from Matlab/Simulink system and simulates wind, gravity and atmosphere. Registration system registers parametres of math model, parameters of Stewart platform, navigation parameters of quadcopters CPU and navigational parameters of collimation system. Stewart platform with six degrees of freedom consists of Arduino Mega, 6 servos and some peripheral devices. Quadrotor CPU stands on Stewart platform and rotate on it. Besides it Quadrotor CPU control the math model through the signals to the brushless motors. Imitator of navigation system simulates the parametres and transmits it to the quadrotor CPU. Collimation system makes the image of environment for modelling the optical systems. As the result the article shows the structure of semi-natural modelling system for the modelling of control system of quadrotor and optical system. | ||
Protasov V. I., Sharonov A. V., Sharnin M. M., Klimenko A. S. Error probability minimization while object identification by onboard computing system of an unmanned aerial vehicle. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/277/protasov_sharonov_sharnin_klimenko_rus.pdf This work set and solved the problem of unmanned aerial vehicles (UAVs) computing power sharing to ensure reliable identification of a number of objects, employing neuron network identification. The main requirement imposed on a group of neural networks’ joint operation is related to incorrect detection of objects in complicated cases, when this probability in a single network is sufficiently great. The authors found the conditions, which fulfillment defines the possibility of forming a group of neural networks, solving the problem of detection of any degree of complexity and returning a wrong answer with the probability not exceeding the preset small value. Theoretical justification of neural networks’ joint operation organization is based on evolutionary solutions adjustment method. On its first stage populations of separate neuron networks solutions were formed, and possible answers were generated, where the room was left for discarding the answer. At the second and subsequent stages the exchange of variants was carried out, and neuron networks, which «discarded» the answer, select, in their judgement, the right answers from proposed answers, or refuse to answer again. This iteration process continues until the majority of neuron networks give coinciding answers. It is quite clear that this answer ca be of three types: <<right>>, <<wrong>> or <<cannot decide>>. The probability values of such answers depend on the number neural networks in the group, problem complexity, initial probabilities of right and wrong answers generation by single neuron networks, and of probabilities of right or wrong selection of foreign answers at the stages of solutions adjustment. To obtain analytical solution of the set problem of defining conditions which fulfillment a group of neuron networks goes wrong with the probability not exceeding the preset small value, the authors employed the result of Condorcet jury theorem and Rasch model. The authors proved the theorem on inconsistent solution of a problem of arbitrary complexity, obtained by a group of neuron networks, probability tending to zero, as well as the theorem on limit value of existence problems’ complexity, which cannot obtain the proper solutions with the pre-set probability. The judgement was exercised, that the proved theorems bear universal character and can be implemented to the group of natural intellectual objects, such as performing the task on context scientific citation number building in complicated cases. The paper describes “error-free” objects detection technology by a UAVs group. Preliminary processing of images under detection was carried out according to the algorithm presented in [11]. Computer simulation of images detection by a group of neural networks confirmed the workability of the approach under discussion and allowed draw inferences on probability value of correct objects detection significant increase in simple cases, and reduce practically to zero the probability value of incorrect detection. | ||
Gainanov D. N., Rasskazova V. A. Mathematical modelling of locomotives' traffic problem by graph theory and combinatorial optimization methods. Trudy MAI, 2017, no 92, http://mai.ru//upload/iblock/430/gaynanov_rasskazova_rus.pdf The paper tackles the problem of railway cargo transportation planning and organizing. Oriented multi-graph of a train traffic energy efficient strategies and a set of this multi-graph permitted paths, i. e. a set of normative threads of a train schedule, are put under consideration. Non-oriented conflict graph is determined on the set of train schedule normative threads, associated with a monotonous Boolean function. The paper envisages the problem of creating a conflict-free set of train schedules, reduced to the monotonous Boolean function maximum upper zero search. The conflict-free schedule threads herein should ensure the specified volume of transportation. For this purpose, conditions of amount of traffic provision should be met, given by correspondence matrix. The transportation plan for the available set of locomotives is formed based on non-conflict set of the graph normative thread sets. A problem of locomotives’ assignment and movement is formulated for the transportation plan, which optimizes the number of completed transportation assignments, a number of used locomotives and a number of «empty runnings». The graph-combinatorial problem of subgraph nodes of oriented graph of transportations dependencies coverage by oriented paths. The above-mentioned criteria herein are formulated in terms of the determined coverage properties. The algorithmic diagram. The main results of the research consist in mathematical formulation of the problem of optimal assignments of locomotives and its reducingtion to the dual graph-combinatorial problem, which solution structure is offered. The obtained results could find an application for solving practical problems on railway transportations optimization with regard to the required fleet of locomotives and its utilization ratio. | ||
Denisov S. L., Medvedskiy A. L. Numerical-analytical method to calculate plate response and durability under broadband acoustic loads and its verification. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/e0d/denisov_medvedskiy_rus.pdf New ICAO requirements for external aviation noise reduction draw increasing attention to the new types of airframe design/layout to use airframe as shield from engine noise. While targeting external noise reduction, the wingbody layout looks like the most promising. This layout places engines over the airframe. It is necessary to note that this layout leads to increase of the airframe area which suffers from acoustic loads. In turn, these loads produce the stresses which can lead to fatigue airframe failure. So despite of significant progress in aviation engine noise reduction, the discussions about acoustic fatigue and durability of aircraft structures (for example, plates and shells) gain back their popularity. In this paper we proposed the hybrid numerical-analytical method to calculate the response and durability of isotropic metal plate under broadband acoustic loads with four different acoustic field spatial distributions: fully correlated, partially correlated, delta-correlated and diffuse field distribution. For the simple-supported metal plate, mean square stresses and durability obtained by the proposed hybrid method were compared with the exact analytical solution. It is necessary to note, that proposed hybrid method may be applied for the plate with clamped-clamped or clamped-simple supported edges. The mean square stresses, calculated by the hybrid method, fit well the exact analytical solution but are highly sensitive to acoustical field spatial distribution, external acoustic field frequency spectrum and number of eigen modes taken into account. We calculated durability by using four different approaches providing the mean square stresses as input data. Calculations performed by Wirsching-Light method (for narrowband Gaussian process) and Kowalewski method (for wideband Gaussian process) give, correspondingly, lower and upper estimations of the plate durability. Miles and Rajcher methods (both are for wideband Gaussian process) produce relatively close values located between the results of Wirsching-Light and Kowalewski methods. | ||
Khokhlov A. V. Long-term strength curves Produced by Linear Viscoelasticity Theory combined with failure criteria accounting for strain history. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/7ce/khokhlov_rus.pdf Interaction of the linear viscoelasticity constitutive equation with several failure criteria is studied under uni-axial creep conditions in order to simulate creep rupture and to assess lifetime of viscoelastoplastic materials or structural elements. The limit strain criterion and two proposed new families of hereditary failure criteria are considered. They are constructed to take into account a whole creep curve and damage evolution. The proposed failure criteria families depend on a positive real parameter and include the limit strain criteria as a particular (limit) case. Every criterion of the first family yields rapture time that is greater than the one given by the limit strain criteria and every second family criterion yields rapture time that is less (or equal) than the lifetime given by the limit strain criteria. The difference between the predicted creep lives can be made negligibly small or considerably large. The failure criteria governing parameters regulate their memory fading rates and provide an additional option to tune the model and fit it to creep rapture test data. Equations of long-term strength curves generated by three chosen failure criteria are derived for arbitrary creep function. Their general qualitative properties and their dependences on the criteria governing parameter and creep function are studied analytically and compared to each other. It is proved that qualitative properties of all three theoretic long-term strength curves are the same as basic properties of typical test long-term strength curves of viscoelastoplastic materials. Thus, coupling the linear viscoelasticity constitutive equation with fracture criteria considered in the paper provides adequate qualitative description of creep rupture and lifetime of viscoelastoplastic materials and structural elements. | ||
Gidaspov V. Y. Numerical simulation of stationary combustion and detonation waves in boron particles with air mixture. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/555/gidaspov_rus.pdf The paper presents the results of numerical studies of ignition and detonation of boron dispersed particles with air combustible mixture. A simplified physico-mathematical model of the process was developed. The dispersed particles are considered two-component and consisting of boron and boron oxide. Material melting and evaporating processes are allowed for, as well as surface reaction or boron oxide formation. Carrying gas is multicomponent staying in thermodynamic equilibrium. The presence of boron fine particles, boron oxide and boron nitride in combustion product is allowed for herein. The structure and minimum velocity of stationary detonation wave propagation, as well as maximum velocity of the flow at stationary-state combustion were obtained by computational method. It was demonstrated that calculated wave parameters asymptotically approach their equilibrium values. | ||
Skorokhod E. P. Photo-ionization cross sections xenon data. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/5fe/skorokhod_rus.pdf Physical — chemical radiation plasma-dynamics promptly developing field of science finding application at the solution of problems of engine building of the space-rocket industry. In [1-9, 14-16] the special attention is paid to computer creation of optical models of gases and the plasmas intended for the solution of problems of radiation plasma-dynamics. Such constructions are based on quantum-mechanical calculations, these or those approximations and semiclassical generalizations of elementary radiation processes. In work [3] for mass calculations the so-called optical model of the environment was formulated. It is necessary to emphasize that in this treatment temperature of the environment and radiation is supposed the general, the Sakha and Boltsman local thermodynamic equilibrium (LTE) is used [6]. In our works [7-8, 14-16] kinetic approach was considered. Constants of different plasma chemical reactions are necessary for this purpose. For reaction of photo-ionization process , ( – concentration of excited state, – a photon energy, – ions concentration) consideration begins with the simplest model of hydrogen and record of matrix elements that is useful for the beginning reader. Calculations of photo-ionization cross sections for hydrogen atom are given. There are Kramers approach [12] for other more difficult atoms, with replacement of the main quantum number by effective quantum number , где , — the potential of atom’s ionization of is used. Values of effective quantum number are given for atom Xe.
The method of quantum defect is considered in details [7]. Results of calculation of photo-ionization cross sections for xenon (the maximum value in a threshold) are given in the table.
The maximum values of photo-ionization cross sections
Xe (in units 10^{- 18 }cm^{2}).
Results of calculation of photo-ionization cross sections for xenon are given on the figure. For the purpose of simplification in case of mass calculations some simplified treatment with use of a formula of Kramers is specified.
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Larina E. V., Kryukov I. A., Ivanov I. E. Numerical simulation of axisymmetric jets using differential eddy viscosity models. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/e5b/larina_kryukov_ivanov_rus.pdf The work deals with numerical simulation using semi empirical turbulence models which include a differential equation for turbulent viscosity in two-dimensional case. k‑ε‑µ_{t} model [5] and k‑ε‑µ_{t}(Λ) model [6] are used to describe the mean turbulent parameters. The one-parameter models of eddy viscosity (ν_{t} −92 [7] and Spalart, Allmaras [8]) are used in one of the jet problems. Averaged flow and turbulence parameters are implemented in Cartesian and cylindrical coordinate systems. Simulation of axisymmetric subsonic jet in quiescent air in initial and transition regions with mean velocity u=87m/s have been conducted using k-ε-μ_{t} model. Initial region length has been determined with reasonable accuracy. Difference between calculated and experimental velocities is less than 5%. Verification of turbulence models in the flat plate boundary layer problem with M = 0.5 have been performed. Skin friction coefficient and velocity in logarithmic coordinates are compared with analytical solutions. Underexpanded supersonic turbulent jet simulation at M = 2 in the nozzle exit [13] have been conducted. Calculated static pressure and Mach number distributions along the jet axis are compared with experimental data. The k-ε-μ_{t} model reproduced 7 jet barrels. The positions of the maxima and minima are closest to the experiment in comparison with other models. The maxima and minima of the pressure oscillations and Mach in all barrels underestimated. The ν_{t}‑92 model reproduced 12 jet barrels that is fully consistent with the experiment. The positions of the maxima and minima are distinctly shifted in comparison with experiment. The k-ε-µ_{t}(Λ) model reproduced the flow similarly with k-ε-μ_{t} model (7 barrels), but predicted flow core length is bigger. Spalart, Allmaras model reproduced only 5 barrels and predicted flow core length is smallest in comparison with other models. Numerical simulation of supersonic axisymmetric jet from converging nozzle in quiescent air [15] has been performed. A comparison with the Pitot pressure and velocity distribution along the axis is shown. The ratio of the chamber total pressure to ambient static pressure equals to NPR=2.5 and 4. In the case of k-ε-µ_{t} model at NPR=2.5 the initial region length is in satisfactory agreement with experiment, but the number of oscillations is underestimated. The k-ε-µ_{t}(Λ) model overestimates the initial region length. Oscillations of the Pitot pressure and velocity have bigger magnitude for all jet barrels in comparison with k-ε-µ_{t} model. In the case of k-ε-μ_{t} model at NPR=4 the Pitot pressure in the first barrel is bigger than experimental value. The difference in amplitude decreases downstream. The peaks begin to keep up and become less appreciable. Pitot pressure produced by k‑ε‑μ_{t}(Λ) model is underestimated in the first barrel. The subsequent barrels predicted by the model are much better than the first. Numerical simulation of overexpanded cold jet using the k‑ε‑μ_{t} model in quiescent air at Mach 3.005 in the nozzle exit [16] has been performed. The calculated axis Pitot pressure is underestimated, but the position of the local maxima and minima and local minima values are determined with good accuracy. The biggest difference along the axis between the calculation and experiment is in the two initial jet barrels. The largest deviation from the experiment in all cross-sections is found near the axis. | ||
Shevtsov S. N., Sibirskiy V. V., Chigrinets E. G. Application of neural networks in predicting the quality of machining of carrying composite structures. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/852/shevtsov_sibirskiy_chigrinets_rus.pdf Manufacturing of new aircrafts requires development and improvement of new materials and technologies, ensuring ever-increasing demands for quality and operation reliability. Most carrying aircraft structures made of polymeric composites are machined to produce the high quality holes providing reliable fixation and assembly of composite structure (such as, spars of the main and tail helicopter rotors blades). Delamination that can reduce the material structural integrity is basic technological problem, occurring while fiber reinforced composite materials drilling. Tool’s geometry and machining conditions are the most important factors affecting the quality of the processed holes. The main purpose of this work consisted in the study the process of drilling holes in a multilayered polymeric composite of “GFRP-titanium” type, which is employed in the design of the Mi-28 helicopter rotor blades spar, as well as for soft tool predicting the quality of the holes development. Using a series of experimental data, including the delamination sizes depending on the machining conditions, the database for the further modeling has been created in a matrix form. Our first attempt to build an empirical description of delamination sizes, depending on two design variables (cutting speed and drilling feed) has been unsuccessful, probably, due to nonlinearity, generic for the drilling process. To overcome this difficulty we proposed and tested an approach, based on the artificial neural networks (ANN) implementation, to predict the quality of the holes drilled in the titanium foil reinforced glass fiber epoxy-based plastics. ANN training has been conducted using an errors back-propagation algorithm. Testing of the prediction accuracy revealed that ANN could provide the quality of size prediction exceeding 97%. According to the obtained results, we recommend to use the artificial neural network for the delamination at the GFRP drilling holes size prediction. In the process of statistics accumulation ANN are able to carry out self-learning and produce the results based on the newly obtained information, and, thus, adequately predict the quality of machined holes. | ||
Makarov L. K. Calculation of the is intense-deformed condition of a wing of the supersonic plane with a defeat means. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/ea4/makarov_rus.pdf For modern warplanes essential complication and expansion of a circle of solved problems is characteristic. At the same time conditions of their operation become complicated: flights are made in a broad band of altitudes and speeds, with various versions of loading on external, including, suspension points. The listed features demand profound studying and an estimation of the is intense-deformed condition (NDS) of configuration items of the plane as a whole and outer wings in particular. Researches of the NDS of the plane on the basis of the conventional approaches which appreciably are based on land and flight experiments, becomes more and more expensive, labour-consuming and long, and, in some cases, and impossible on safety conditions. The numerical methods using modelling of a design of the plane in the form of beam and balochno-lamellar schemes [1], have limitations at NDS calculation. Now the increasing role is played by the new approaches based on wide application of modern numerical methods and computer technologies [2,3]. In the known literature [4,5] at calculation of the NDS of a wing with aviation means of defeat (ASP) the interference between them is not considered. Nevertheless, between a wing of the plane and подкрыльевым ASP there is the significant interference interaction characterised by presence of horizontal, vertical and lateral interference forces [6,7,8]. Significant on value interference forces lead to occurrence in a wing additional bending and torques that essentially changes its NDS. Thus, working out and application of the techniques, allowing to consider influence of interference interaction between a wing and ASP on the wing NDS, is an actual problem. In the present activity results of an estimation of reliability of calculation in program ANSYS of parameters of the NDS of an outer wing of the plane are presented at supersonic speeds without aviation launching sites (APU) and with them, executed by comparison of experimental and computational values. Besides, results of research of influence of an interference on the outer wing NDS are presented at various rules ASP underneath the wing. | ||
Isaev A. I., Mairovich Y. I., Safarbakov A. M., Khodatskii S. A. The study of air-fuel mixture formation process in pulse combustion chamber and thermodynamic computation of pulse combustion. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/4c8/isaev_mayrovich_safarbakov_khodatskiy_rus.pdf Many known projects of pulsejet realize the Humphrey cycle in their operation. Practically all the projects are aimed at argumentation of the pulse combustion chamber design. In the course of the pulsejet development, designers do not pay much attention to fuel-air mixture formation, though this process determines the combustion efficiency, and, as consequence, the amount of hazardous emissions, to which more and more strict requirements are placed. While fuel-air mixture formation, it is necessary to organize a volumetric circulation zone to spread it over the entire volume of the combustion chamber. The existing ways of circulation zones organization do not provide their large volume. When pulse combustion chamber design, it is necessary to control the flow in its air-gas channel to achieve the greatest possible volume of the circulation zone. We solve the scientific problem to ensure the mixing process in the pulse combustion chamber. The main purpose of this work is the process of pulse combustion organization of the fuel-air mixture. Scientific novelty of the work includes: — argumentation of pulse combustion chamber design; — technological process developing of fuel-air mixture organization in flowing combustion chamber with pulse fuel supply and its combustion; — development of methods for calculating parameters of the gaseous atmosphere in pulse fuel-air mixture combustion in the pulse combustor. | ||
Krovjakov V. B., Romanov A. A., Koroteev A. Y., Yalpaev A. A. Hydro-pulse-jet cleaning-out and aircraft liquid systems and components working cavities pollution control. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/e3d/krovyakov_romanov_koroteev_yalpaev_rus.pdf Solving the problems of industrial purity (IP) of fluid systems and components (FSC) working cavities, and implementation of working and process liquids (WPL) of aircraft (AC) can significantly reduce consumption of liquidsю It also increases reliability and service life of onboard equipment (as a consequence, improves the flights safety); reduces the aircraft maintenance and servicing time (as a consequence, increases the aircraft combat readiness); reduces the complexity of maintenance. The object of research in this entry are the methods and means of ensuring aircraft FSC working cavities IP. The purpose of research consists in developing technological solutions and advanced hardware designs for effective treatment and control of contamination level of oil, fuel, hydraulic systems and components. Research subject refers to the priority areas of science, technology and engineering in the Russian Federation: NoNo 5, 7, 8, 9, and to basic critical technologies in the Russian Federation: NoNo 1, 24, 27 (Presidential Decree of 07.07.2011, No 899). During scientific research the authors carried out the following: analysis of the existing and prospective methods and means of cleaning-out and its quality control. They defined the trends for cleaning-up efficiency enhancement and its control validity. Cleaning-up technology consisting in FSCs’ internal cavities bleeding (with pressure and velocity fluctuations) was defined as a basic one. The obtained in the presented study significant positive effect on quality and duration of the cleaning-up process is achieved due to the fact that unlike existing technologies, the developed hydro-pulse technology realizes the non-steady fluid flow mode by periodic change of flow rate from zero to the value, effective for specific cleaning system without creating fluid pressure fluctuations (patent RF 1568343). Compared to domestic and foreign counterparts, this technology allows 2 to 3 class (according to GOST 17216-2001) quality improvement and 5 to 7 times cleaning process duration reduction, up to 10 times liquid systems and assemblies plunger resource increase. FSC IP level control is one of the most important manufacturing operations. It defines aircraft tolerance for use according to the drive parameters on one hand, and the aircraft manufacture, repair and maintenance on the other hand. It defines the moment of the FSA cleaning operation process termination, which occupies a significant portion of the total of the works on their service duration. For complicated spatial geometrical parameters of aircraft FSA internal cavities relevant Regulations foresee execution of their pollution indirect control ‒ measuring the contaminants concentration in the outflowing fluid from the controlled FSA during bleeding in the rinse mode and operation mode. In these circumstances, special attention should be paid to liquid sample drawing process. To improve the reliability of the liquid sampling the authors developed and and proposed methodologies and design solutions of sampling devices (SD) along the lines of: – full flow SDs, ensuring isokinetic sampling, as maximally identical to the object of analytical control, from which it was sel ected for use in ground bench (test, developmental, washing) equipment; – needle type SDs constructively with minimal weight and size fit to normalized elements of aircraft FSA reinforcement pipe systems, for their accommodation directly at the aircraft onboard systems, in coordination with the aircraft developers. The presented technological and design solutions are cross-industry and cross-samples value and apply to all objects of weapons, military and special equipment, containing in its design, fluid (oil, power, hydraulic, fuel, etc.) systems and units. The equipment developed in cource of the presented work is implemented in the OJ-SS “NIIASPK” serial products manufacturing (aviation industry), technical Adoption Deed of 21.04.2016, the results of the research on the technologies development implemented in Academy research effort and aviation industry, including those carried out by the State contract fr om 09.01.2014, No 14411.17B9999.18.001 for PAO "NPK"Irkut", the Adoption Deed of 17.03.2016, 01.06.2016 r .; in the educational process of the Academy, Adoption Deed of 01.06.2016 (the Implementation and Realization Acts are included). | ||
Bolkhovitin M. S., Borovikov D. A., Ionov A. V., Seliverstov S. D. Micro gas turbine engine test bench development. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/25c/bolkhovitin_borovikov_ionov_seliverstov_rus.pdf This article is devoted to problems of development and experimental studies of micro-jet engines (micro gas turbine engine with a thrust of up to 1000N). The main focus is a test bench for engines of this class. During the project are solving the following tasks:
Presently, the authors are carrying out researches of designed micro-jet engines with thrust 100N and 400N using created test bench. The test bench works on the research of regime parameters of engines, as well as working out the design of the engine. Test bench consist of a mechanical part, movable rails for fixing the engine, test bench control system and measurement system. Test bench control system allows providing power to other systems: fuel pump, valves, measurement system, as well as start and ignition systems. Regulation is carried out by single parameter — fuel consumption. The measurement system includes: speed sensor, temperature sensor, fuel consumption sensor and thrust sensor. Test control and data collection are automated and are conducted by LabView environment. Engine is mounted on rails for ease of moving and assembly / disassembly, as well as allowing of its moving in the axial direction during thrust. Also, during 400N engine experimental research, defined it starting diagram, recorded correlation between fuel consumption and thrust. A test launch of 400N engine allows verifying it numerical model. Based on this verifies, for engines up to 1000N calculation software, is under developing. | ||
Mulin P. V., Berezuev A. V. Signal generation on mnemonic indicator for manual thrust control mode during landing approach. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/83a/mulin_berezuev_rus.pdf The subject of research and development consists in signal generation on a mnemonic indicator algorithm development for a seaborne aircraft. Research methods include system analysis, synthesis of structures and algorithms, simulation. The work aimed at a signal generation on the mnemonic indicator technique determination. The model included atmospheric turbulence, the mnemonic indicator, dynamic airplane control structure, and aircraft dynamics. The simulation models consisted of multiple systems of differential equations. The system was linearized for simulation. The signal generation on mnemonic indicator technique is offered for a seaborne aircraft manual thrust control mode during landing approach. Its basis is formed by complexation of signals, indicating flight speed deflection, angle of attack deflection and normal acceleration component, with no delay in a control loop. It allows correct dynamic characteristics of angle of attack thrust control loop, make them similar to flight speed deviation control, and simplifying by this the pilot’s task of aircraft holding in an permissible zone of the angle of attack variation in conditions of wind disturbances. Angle of attack control loop modeling for manual thrust control mode in the conditions of wind action were carried out. The Dryden gust model and a Monte Carlo simulation approach were used. Recommendations on a signal generation at the input of the mnemonic indicator algorithm parameters are given. | ||
Pchelnikova-Grotoba O. N., Min M. T. Resource assessment of solar energy for the supply of airport ground systems in the Republic of Myanmar. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/d3d/grotova_min_rus.pdf The calculation of the guaranteed monthly average of solar radiation on the territory of Myanmar. The influence of the angle of inclination of the receiver of solar radiation to the solar radiation and the sel ected optimum tilt angle of the receiver. For some objects, distant from power grids over long distances, perhaps only Autonomous power supply, as connecting them to the centralized system requires a large capital outlay associated with the construction and operation of long transmission lines. For such objects the cost of electricity generated from renewable sources of energy becomes commensurate with the cost of electricity generated fr om power systems, and this factor ceases to be limiting for the application of renewable energy sources. In addition, Autonomous fuel-fired power plants have a lower quality of electricity, and when energy generators based on renewable energy sources gain great prospects to compete. The current values of solar radiation intensity and duration of their action depends on latitude, climatic zone, time of day and year, and other factors. Because of this they are random, so the probability of its intensity corresponds to the probability that the random variable in the interval: To increase the solar radiation by orientation angle of the receiving site. It is therefore necessary to calculate the optimal angle of the receiver solar radiation with the aim of maximizing the solar radiation during the year as a whole, and for monthly optimization of this angle. Comparing the arrival of solar radiation at different angles of the receiver of solar radiation in the cities of Myanmar we can conclude that the arrival of solar radiation during the installation of the receiver the solar radiation at an angle β_{сез}is reduced in all regions of Myanmar approximately 1 % in comparison with the arrival of solar radiation during the installation of the receiver the solar radiation at an angle β_{мес}. Therefore, the best option is the orientation of the receiver of solar radiation with the seasons twice a year, which allows no additional cost to the complexity of the solar system installation to a significant increase in the arrival of solar energy. | ||
Tiuvin A. V., Afonin A. A., Sulakov A. S. Features of using functionally redundant accelerometer blocks in strapdown navigation and gravimetric complexes. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/60d/tyuvin_afonin_sulakov_rus.pdf This article deals with questions of strapdown graviinertial complex (BGK) efficient version design, redundant structure of its primary information sensors and advanced functional operation algorithm, making it possible to achieve sufficient accuracy of vector gravimetric measurements and determine the orientation and navigation parameters. The purpose is achieved through the use of functionally redundant blocks of inertial sensors, as well as through evaluation and correction of errors of inertial and satellite components of complex navigation system directly in the gravimetric survey. Functional algorithm is based on the basic equation of the inertial navigation with the use of optimal Kalman filtering methods in the case of a tightly coupled structure of a complex navigation system. The technique of functionally redundant blocks inertial sensors data treatment is presented. The listed mathematical expression are showing that an increase in the number of block units increases strapdown graviinertial complex accelerometers accuracy. A method of selecting a rational design of the accelerometers block with cone structure is describe. It is indicated that, in general, the best half-angle of the cone depends on the ratio of measurer statistical error model coefficients and the value of the measured vector. Calculations of inertial measurement unit with cone structures optimal configurations have shown that increasing the level of inertial measurement unit redundancy increases considered technical solution efficiency. For example, compared with the three sensors inertial measurement unit, in the case of four sensors influence the random error can be reduced by 14%, for the five sensors — 23%, six — 29%. | ||
Antonov D. A., Zharkov M. V., Kuznetsov I. M., Lunev E. M., Pron'kin A. N. Unmanned aerial vehicle positioning based on photographic image and inertial measurements. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/777/antonov_zharkov_kuznetsov_lunev_pronkin_rus.pdf Onboard equipment of middle range (MR) grade (UAV) must include an advance navigation complex, forming navigation data for control system. This data must meet high accuracy, availability, integrity and continuity requirements to provide safe flight and successful flight mission execution. In addition, hardware of MR UAV navigation complex must meet high weight and size, power consumption and final cost requirements. Meeting mentioned requirements causes use of low-cost and small-size systems and sensors of primary information, which in its turn causes the necessity of use primary data processing mathematical techniques, allowing to achieve defined performance. Required accuracy provision at different stages of flight for this UAV grade simultaneously increasing control automation today is not completely solved task. Landing is one of the most complex stages of flight and capability of automated landing depends heavily on the accuracy of navigation parameters determining. The majority of existing systems providing automatic UAV landing proposes use of global navigation satellite system (GNSS) integrated with inertial navigation system (INS). However, it is well known, that GNSS signals cannot be always available including jamming cases. Therefore, it is advisable to explore possibilities of INS integration with other systems, which are free of GNSS disadvantages to analyze the potential accuracy of navigation parameters determining. Based on photogrammetry artificial landmark image processing attitude and navigation system (photogrammetry system — PS) is sel ected as such system in this article, which has a high degree of autonomy and of insensitivity to interference as compared with GNSS. Due to the principle of its action PS is commonly used at landing stage and for its operation uses the photographic image fr om the onboard camera, which is usually a part of UAV onboard equipment. An option of scheme design and algorithms of INS and PS integration for use at UAV landing stage is offered. Required for synthesis of integration algorithms mathematical errors models of INS and PS are considered. | ||
Lebedev G. N., Mikhailin D. A., Roumakina A. V. Non-measurable flight parameters multi-stage identification while on-board measuring tools’ signals complexing. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/c00/lebedev_mikhaylin_rumakina_rus.pdf The problem of non-measurable flight parameters identification, including wind affects and remained fuel weight, appeared necessary information for safety and flight control monitoring. The authors offer a multi-stage procedure of assessment, according to which less precise, but simpler means are implemented at the initial stages of assessment, while more complicated elements are put into operation as may be necessary. A complexed two-stage identifier of side wind is formed, consisting of a windblast estimation block, a block of its steady state value evaluation and a block of logic switching from one estimation to the other, using aperiodic filtering for the first case and modified Kalman filter for the other. The identifier, employing optimal Kalman filter prognosis operation, provides the most precise indirect estimation technique of the steady-state wind. The authors offered “freezing” the most significant for evaluation correcting matrix coefficients of optimal Kalman’s filter, and zero the rest coefficients, so as to eliminate variable coefficients and provide offload the onboard computer. According to the offered multi-stage identification concept, every stage employs different set of sensors. Satellite navigation data appears more useful for the situation of initial wind effect, as well as a group onboard sensors, such as accelerometers and airspeed sensor, reacting faster to wind changes than other sensors. To evaluate the steady-state value, other sensors, controlling the aircraft reaction, mainly, to the constant wind component effect. | ||
Eliseev V. D., Evdokimchik E. A., Kotel'nikova A. V., Chemodanov V. B. Formation of astatic control systems of objects with uncertain parameters on the basis of a modal-invariant subsystem. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/c1a/eliseev_evdokimchik_kotelnikov_chemodanov_rus.pdf The object of article is the method of formation astatic control systems of dynamic objects with uncertain parameters on the basis of robust modal-invariant systems. The methods of formation static control systems for dynamic objects with uncertain parameters on the basis of the theory of modal-invariant systems are well known. The established value of controlled coordinate in the presence of parametrical errors and action of constant disturbances of object in such systems is a variable. There is a problem of formation of astatic system on the basis of a modal-invariant subsystem with integrating property. Thus there is no necessity for traditional addition of an integral link. It allows not to increase an order of system and represents practical interest especially at a hand control. Integrating properties of system are reached at the expense of maintenance of a zero root in the characteristic equation of a subsystem by known methods of modal control. After closing of system by feedback on the controlled coordinate we create astatic system. The offered method of formation of linear astatic system with preliminary formation of structure and parameters of a modal-invariant subsystem with integrating property provide astatism on control and disturbing influences, and also the lowered sensitivity to uncertainty of parameters of control object. The example of synthesis of astatic system is given and the possibility of reduction of its sensitivity to uncertainty of object parameters is shown. | ||
Tikhomirov A. V., Omel'yanchuk E. V., Semenova A. Y. Examining the possibility of selectivity increasing of low-pass filter with linear phase response. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/787/tikhomirov_omelyanchuk_semenova_rus.pdf The paper envisages the possibility of a low-pass filter sensitivity without its phase response deterioration. At present, high-speed radio data transfer lines operating in perspective frequency bands (such as K-band), digital means for radio signal filtration, meeting the Radio Regulations requirement do not exist. In this case, additional analog filter is added to radio transmission path. This causes intersymbol interference (violating Nyquist condition). Intersymbol distortions occur herein, caused by non-linear character of phase responses of the applied LPFs. Thus, the necessity of data transfer speed increase of radio channel data transfer (and, correspondingly, the effectiveness of radio frequency spectrum implementation) determines the necessity of carrier shaping by the filter with maximum amplitude-frequency response slope. The selectivity of the filters with group delay approximation is inferior to filters with amplitude response approximation. It to employing additional low-pass filters, deteriorating the group delay uniformity in the passband. One can conclude that the filter calculation implies compromise between frequency response slope outside the passband and the group delay uniformity in the passband. This problem can be solved by combining LPF with linear frequency response (such as Bessel, Gauss or Papulis filters) and notch sections with transfer function zeros outside the LPF passband to obtain the frequency response with greater slope without significant effect on phase response and, correspondingly, group delay. Implementation of notch elements with the rejection frequency selection irrespective of LPF cutoff frequency seems to be the most perspective technique. On an example of implementing the fifth-order Bessel filter for filtering out spectral components of impulse signals, the authors prove that the proposed technique allows ensure gain in suppressing minor lobes of pulse signal, while preserving the group delay uniformity. | ||
Dobychina E. M., Snastin M. V., Obukhov A. E., Haralgin S. V. Airborne radar antenna array test at the antenna measuring and computing complex. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/5ce/dobychina_snastin_obukhov_kharalgin_rus.pdf The paper considers the antennae arrays testing set carried out at the anechoic chamber (AEC). Automated measuring and computing complex (AMCC) was used for high-frequency feeders of centimeter and millimeter band slotted waveguide antenna arrays (SWAA), mm-band preamplifier parameters, estimating of mm-band airborne radar radome parameters, transparent radome influence at the mm-band SWAA performance measurement. Comparisson of the basic measured parameters with same antenna array measurements at the far field test range is presented. To define SWAA gain the absolute reflection from a mirror technique was applied. Its idea consists in comparing reflection coefficients from the fider matched measured space radiating antennae arry (AR) input, and from the input of the same antennae with a reflecting surface, installed at some distance of R in front of it. It may be either flat screen, or reflector. The matching disruption is explained by the antennae input impedance change affected by the flat screen, which is equivalent to the effect of the same antennae, but located at the distance of 2R and operating with opposite oscillation phase. The gain measurement error value caused by chamber walls reflections, and nonideal antennae input and fider matching, while oprating in free radiation mode, were defined by statistical averaging of measurement results obtained for various distances to the reflector. Experimental studies of absolute antenna gain measurement absolute reflection from a mirror technique demonstrated measurement accuracy of about of 0.5 dB match with far field relative technique measurements. These studies proved the possibility of narrow beam antenna array measurement at the near field. In the course of the studies another antennae parameters measurement technique was mastered, and a series of experiments was carried out. Anechoic chambers impllementation allows signifficantly reduce or even completely eliminate the far field test range tests. It leads to significant cost and time savings associated with complex electronic equipment development. | ||
Ananenkov A. E., Маrin D. V., Nuzhdin V. M., Rastorguev V. V., Sokolov P. V. To the question of small-sized UAVs surveillance. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/592/ananenkov_marin_nuzhdin_rastorguev_sokolov_rus.pdf The article is devoted to the problem of the detection and coordinate measurement of small unmanned aerial vehicles (UAVs) in the city with strong reflections from the local objects. This problem is related to the rapid growth in the number of UAVs and with a relatively soft laws aimed at the regulating and organizing of small UAVs flights. Therefore, it is necessary to provide the safety of the important objects and places with mass of people from possible threats associated with the use of small UAVs and to monitor the air space at any time and in any weather conditions. Only radar sensor meets these requirements. It’s noted that there were attempts to solve this problem with using military radars that designed to detect mortar and artillery shells. But these radars are very expensive. Therefore, truly effective solution to this problem is the producing of a cheap short-range radar system for detection and tracking of such UAVs. However, using the radar for these objects that fly at low altitude, is associated with the complexity of the detection process. This is due to the presence of spurious background reflections from objects of urban area. These reflections exceed echo-signal from UAV by orders of magnitude. The methods for detection of small-sized aerial objects against the background of intense reflections from the underlying surface (US) were noted. The detection can be implemented by extending the spectrum of the probing signal (PS) with reducing the pulse duration. This PS does not have side lobes of range selection function (SF) that allows to observe small target in close proximity to major. Using an ultra-short pulse (USP) PS allows to apply inter-periodic compensation methods, that allow to solve problems related with the small radial component of the velocity vector of the UAV. The results of the radar field tests in terms of urban development are presented. It was able to detect hovering and low speed UAVs during the experiment. Echo signals of several production samples of UAVs were investigated. The algorithm of calculation and the obtained values of average radar cross-section (RCS) for the UAVs are presented. The images of radar indicator with source data for different durations of the PS, including the UAV marks, are noted in the article. The authors note that measured average values of RCS using USP radar are large enough for stable radar detection UAV at 3-5 km range. | ||
Timoshenko A. G., Teplyakov I. M., Kuznetsov V. S., Solodkov A. V. Energy stealthiness ensuring technique during the target coordinates determination. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/895/timoshenko_teplyakov_kuznetsov_solodkov_rus.pdf The article describes the problem of creating a location system based on mobile units, adding new functionality without changing the communication systems’ hardware component count. Target detection by equipment employed for communication systems equipped with vertical pin vibrators is limited not only by the parameters of the antenna radiation pattern, but also by the level of the amplifier maximum output power level, usually not exceeding 5 W. The Defense Advanced Research Projects Agency (DARPA) started the realization of a similar air-based project for deploying on unmanned aerial vehicles this year. The proposed decision is aimed at the modernization of the existing mobile subscriber communications with antenna suspension height not exceeding 2 m. To ensure the energy stealthiness of wireless devices operating in radar mode and determining the local coordinates of targets the proposed method consists in using simplex codes with a large base. The carried out computations revealed, that implementation of codes with 4096 base as an expansive pseudo-random sequence, can ensure energy stealthiness at the level of —20 dB with a probability of target detection no less than 0.9, and the probability of false detection of about 10^{-6}. It is possible to build Kasami family for the selected base. The authors carried out computation of target detection parameters, and defined the target distance error, which amounted to about 5 m, with a detection distance of about 5 km and an effective scattering area of a target of about 6 m^{2}. The proposed method is expected to be tested on radio communication mobile devices, with an output power up to 5 W, and omnidirectional antennas. For the obtained data analysis, an earlier proposed modified Fortune algorithm will be used, when the curve is used sweeping right line for Voronoi diagrams plotting. Such an approach will allow reduce the target errors in range up to 2.5 m and azimuth up to 10^{–3} rad correspondingly. Thus, the number of communications devices involved in the location should be greater than three, including no less than two radiation sources, operating alternately. | ||
Mikhnenko N. K., Vakhromeev P. V., Ktitrov S. V. Determination of the optimal aircrafts assignment for carrying out search and rescue operations. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/8c0/mikhnenko_vakhromeev_ktitrov_rus.pdf We consider the problem of determining the optimal assignment of aircrafts for carrying out search and rescue operations (SRO) based on the assumption that only one aircraft is allowed in the zone during the SRO. Every zone, attainable fr om given aerodromes should be taken into account [1]. The goal is to maximize the total search time by all involved aircrafts. In order to ensure compliance of both conditions, we proposed to solve the problem in two stages. The goal of the first stage is to maximize the number of aircrafts that can be assigned to the SRO zones assuming the latter are reachable fr om the given aerodromes. The goal for the second stage is to maximize the total search time. We can assign the task of finding the maximum possible aircrafts, which can be distributed to the SRO zones in the form of matchings “type of aircraft / aerodrome” (TA), as follows:
subject to:
where m – the number of SRO zones; k – the number of different TAs; h_{i} – the amount of aircrafts of i^{th} TA; x_{ij} – variable, that adopt values either 1 or 0, depending on whether the aircraft of i^{th} TA is assigned to j^{th} zone SRO or not. We represent the assignment of the second task in the following way:
subject to:
where t_{ij} – search time of the i^{th} TA in j^{th} zone SRO (taking into account flight time to the zone SRO since departure and flight time to return to the aerodrome); — the goal value (1). We proposed to consider two methods of solving assigned tasks: • Simplex method; • Methods based on algorithms for solving Boolean satisfiability problems (SAT). It is necessary to emphasize that assigned tasks belong to the class of pseudo boolean (PB) linear programming problems (LPP). In most cases, algorithms, based on the simplex method, are applied to solve the problems of this class, as a result of the inapplicability of itself. However, due to the structure of assigned tasks, it is possible to use simplex-method without any modifications to obtain the optimum PB solution. In recent decades, the determinants of Boolean satisfiability (SAT Solvers), based on the SAT methods, have made significant progress. The record performance of modern SAT Solvers opens up new prospects for their use in applications wh ere previously it was considered to be possible only conditionally. However, due to the NP-completeness of the SAT-problem, there are examples, the time, required to search for the optimum solution of which, is showing the exponential growth. One of SAT approach inapplicability cases is demonstrated later in terms of assigned tasks by the example of the currently best SAT Solver in PB LPP category [2]: Nagoya Pseudo-Boolean Solver (NaPS) v. 1.02b [3]. During the analysis of the assigned tasks, the algorithm, that under certain conditions, related with input data, can reduce the dimension of the assigned tasks, was developed. It is given below: Suppose k TA and m SRO zones are given. Furthermore, we can distinguish SRO zones, attainable only by i^{th} TA.
Then the algorithm becomes as follows:
Testing the effectiveness of the developed algorithm was carried out with solutions sensing method (SSM) [4]. SSM — is the method for solving PB LPP, which has exponential complexity. Consequently, it is particularly sensitive to reduction of the assigned tasks dimension. This became the reason of selecting this method. We will use the abbreviation of MSSM for SSM modification with the developed algorithm.
Figure 1 — Comparison of SSM and MSSM effectiveness growth Based on the results (fig. 1), the following conclusions can be made:
Examples, which evaluated the effectiveness of the selected approaches, can be divided into 2 groups:
This separation is explained by the following formula:
demonstrating the increase rate of the solution space, depending on the input data.
Figure 2 — Illustration of the Naps 1.02b results for the 1^{st} group of constraints
Figure 3 — Illustration of the Naps 1.02b results for the 2^{nd} group of constraints Time spent to find the optimal solution of the same test examples using the simplex method in all cases did not exceed 3 ms. According to the results of the tests (fig. 2, fig. 3), the following conclusions can be made:
Based on these results it is the simplex method we proposed to use for solving such class of problems. | ||
Busurin V. I., Kazaryan A. V., Korobkov V. V., Yin N. W. The study of ring resonator first and second modes of deformations effect on characteristics of angular velocity transducer based on optical tunneling effect. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/8da/busurin_kazaryan_korobkov_yin-naing-vin_rus.pdf This paper presents adjusted mathematical model of angular velocity transducer (AVT) based on optical tunnelling effect (OTE). The effect of the initial gap, the optical source incidence angle and optical spot radius on the of the angular velocity transducer based OTE characteristics is calculated at different angular velocities. The article studied the effect of the ring resonator primary and the second mode of angular velocity transducer based on optical tunnelling effect (OTE). The initial mathematical model assumed parallel displacement of the gap between the prism and ring resonator. It determined optical output power on photo detector by the optical spot central point. In real configuration, the ring resonator surface is deviated a few nanometres from the prism surface. Considering the gap variation for different contact points of the optical spot, it is possible to determine the adjusted mathematical the primary mode model. In the secondary mode, the adjusted mathematical model is defined based on the gap change at various points of the ring resonator surface. The OTE-based angular velocity transducer is implemented using the results of the initial and adjusted mathematical models. Optical output power is defined according to the compensated mathematical model by various contact points on the prism border. This paper presents the study of the OTE-based angular velocity transducer, and proposes the adjusted mathematical model for the ring resonator first and second modes. The authors considered the effect of the output power errors when using the adjusted mathematical model compared to the initial model with variation of the initial gap, radiation source’s incidence angle, and the optical spot radius. The paper demonstrates that the optical spot radius affects strongly, and for relative error, no more than 1%, the optical spot radius should not exceed 50 mcm. Incidence angle herewith affects the output signal, and it can be changed within the range from 42° to 50°. The results of the article allow study error elimination while AVT design. | ||
Zagrebayev A. M., Ramazanov R. N. Searching for the best time shift for the fastest reactor recovery to nominal power after reactor trip. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/e9b/zagrebaev_ramazanov_rus.pdf A force majeure resulting in the necessity for temporary reactor trip may occur at the nuclear power plant (NPP) while normal operating mode. The paper envisages one of the operation c aspects of nuclear power plant operation in force majeure conditions. The station is assumed to consist of several power units being at various stages of the campaign. Let there is a necessity to NPP trip due to a force majeure. The threat termination can occur at an arbitrary point of time either. It is quite clear that not all power units in general will be able to raise the power up to nominal value immediately. This difference can be stipulated by, for instance, the presence of different operating reactivity margin for xenon poisoning compensation, or, in general, by different maneuver effectiveness. The authors consider the system, consisting of two reactors. With brief shifts between reloads after unscheduled trips of both reactors, a period exists when neither can restore nominal power, since both stay in iodine well. For the rest of time both reactors can restore nominal power in no time. On the contrary, with large time shifts one of the reactors at a certain point would possess reactivity margin to compensate the iodine well, when the other still stays in the iodine well. If the reactor stays at such a campaign stage, that it is impossible or undesirable to handle the control rods, to get out of the iodine well one should alter boric acid concentration in the active zone. Reactivity margin due to boric acid presence in the coolant is proportional to its concentration. Let the boric acid concentration time dependence within single campaign be approximated with enough accuracy by linear function. Since the moment of trip is random, we can speak about average flow time for starting one reactor at the power level depending on the shift. The paper offers setting and solution of the optimization problem for selecting the best time shift between the off-load refueling of nuclear reactors, allowing quick start of at least one unit after the reactor trip. This work demonstrates that the time shift between off-load refueling allows quick launch of one reactor, but does not allow the start of both. In the general, for NPP consisting of N reactors the optimum shift is 1/N of the reactor campaign. | ||
Vasilyev S. V., Demchuk V. A. Support of the functional stability of the board integrated computer systems. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/354/vasilev_demchuk_rus-.pdf Integrated computer system (ICS) operation in real conditions is associated with occurrence of various module failures, caused by destabilizing effects. The separate module failure herewith may lead to either system crash, or functioning in degraded performance mode, possible at the expense of reallocation of damaged module functions between the system good modules. One of possible system responses to failure consists in functional reconfiguration, while the system feature to keep the ability to fulfill its specified functions with required quality in conditions of functional failures is interpreted as functional stability. ICS reconfiguration task in flight requires permanent monitoring of the system condition, and decision making on optimal ICS configuration according to a known rule. System reconfiguration capacity defines directly its functioning safety and the task performance quality as a whole. Redundant resources available in the system define the above said abilities while of failure occurrence. Thus, the task of optimal (rational) ICS structural synthesis at the stage of design with restrictions on employed resources seems to be topical. The paper envisages algorithm of optimal distribution of aircraft ICS at the design stage, ensuring maximum level of functional system stability during failures under operation. For this purpose, the system structure is represented in the form of marked oriented weighed multigraph, which peaks match the system modules, while its arcs match the functions, executed by the given units. Such functions are defined as internal. The external functions call, or the system tasks, are determined as some assemblage of possible paths in the column for each external function. ICS structure representation in the form of the weighed digraph allows examine various versions of ICS structure in the condition of degradation, that is, a certain unit inability to execute specified function. Degradation leads to removal the ribs matching the given function from the column. Thus, the approach, which allows examine in-process the effect of units’ failures on operability of the remaining intact is offered. It means that the capability of functional links registration between the units, specific to hardware systems is employed. Resources redistribution within the limits of the offered algorithm is examined in two ways. Firstly, it is oriented on reaching external functions calls maximum execution quality at a runtime environment of everything not below the specified level. Secondly, it assumes redistribution of hardware-software means corresponding to a maximum execution quality of critical external functions calls. Selection of optimal ICS structure within the limits of the accepted strategy of resources redistribution is determined by optimization. In-process two criteria are offered (a survivability index, a figure of merit), which applicability is determined by singularities of particular ICS. The paper presents the results of numerical simulation. The offered algorithm can be used at the ICS design stage to meet the requirements on fail safety and survivability. | ||
Tochilova O. L. Wavelet Analysis of Missile Stability. Trudy MAI, 2016, no 91, http://mai.ru//upload/iblock/95a/tochilova_rus.pdf The paper is devoted to development of new statistical data processing technologies obtained during simulation of missile motion in accordance with the complete mathematical model for a big quantity of randomly realized sets of tolerances, each of them is characterized by a specific transient process. The necessity for the research has emerged in connection with the fact that existing diagnostic methods did not allow identify variants of tolerance combinations, whereby the oscillations with frequencies, amplitudes and durations exceeding the design values, occur in the respective transient processes. The process of critical variants manual study is labor intensive and ineffective. Not only is the information on the spectral content, but also the spectral components temporal localization is of interest herewith. Thus, the classic Fourier processing, with only frequency representation of a signaldoes not allow solve this problem. A new methodology is described, allowing automation of the frequency and time domain analysis process of a large quantity of nonstationary signals. This methodology is based on the implementation of wavelet and wavelet package transformations of one-dimensional signals to obtain their frequency and time presentations, and subsequent analysis with pre-set parameters. The paper presents an example of the developed methodology implementation to reveal the variants of tolerances combination, located on the stability boundary, where oscillations’ with frequency, amplitude and duration higher than the preset values present in the respective transient processes. The main results of the developed technique implementation for stabilization algorithm parameters adjustment are presented. | ||
Zaitsev V. V. Evaluation of integral funnel in aircraft dynamics on exposure to uncontrolled factors. Trudy MAI, 2016, no 90, http://mai.ru//upload/iblock/8c7/zaytsev_rus.pdf Consider a dynamic system under limited uncontrolled factors impact is under consideration. A problem of aircraft movement study in many cases narrows down to such systems research. Uncontrolled factors of no little significance can be aircraft aerodynamic characteristics approximation errors, forces and moments allowing for wind impact, atmosphere characteristics deviation from normal (and corresponding disturbance in aerodynamic characteristics). It is common knowledge that solutions for non-linear systems can be obtained in special cases. Thus, the problem of a system phase flow evaluation arises (in a corresponding definition — evaluation of system integral funnel). This work considers the system with the same critical points nonoccurrence for all parameters, or system critical points nonoccurrence in the region under consideration. The main problem of the known method of comparison is lack of comparison systems building algorithms for common non-linear systems. The paper considers corresponding comparison systems building for systems with «drift» and estimation improvement issues. Comparison systems are developed using various generalizations of Lyapunov special functions (the system of functions with equiscalar surfaces distorted by hyperplanes in particular). The temporal separation of the integral funnel under study is evaluated (in particular) as an intersection of sets, bounded by Lyapunov special functions surfaces. The possibility of obtaining high-accuracy evaluations is demonstrated in some suppositions. The paper gives examples of system solutions evaluation for planar motion in a vertical plane for the problem of estimation of errors impact while aerodynamic performance characterization on the system phase flow. Methods and corresponding algorithms for a dynamic system integral funnel estimation suggested in this work can be effectively implemented in theory of differential equations (solutions evaluation), control theory (attainability domains estimation), aircraft and spacecraft dynamics applications (allowance for aerodynamic coefficients errors, wind impact, etc.), as well as for motion ballistics and dynamics of submersible craft in games theory dynamic problems. The indisputable advantage of the suggested techniques consists in obtaining analytical functions describing estimations and high efficiency of algorithms. The result of the suggested technique presents warranted estimations contrary to direct integration (which allow integrate finite number of trajectories, and using additionally methods of integrating results processing obtain some heuristic evaluations). | ||
Aslanov V. S., Alekseev A. V., Ledkov A. S. Harpoon equipped space tether system for space debris towing characterization. Trudy MAI, 2016, no 90, http://mai.ru//upload/iblock/5fe/aslanov_alekseev_ledkov_rus.pdf This paper studies a process of space debris removal by space tether system. The stages of space debris capture by a tethered harpoon and commencing of towing are considered. The system consists of a tug, equipped with low thrust engine; a passive object, i. e. space debris, modeled by a spread rigid body, heavier than the tug, and an elastic tether. The aim of this paper consists in defining the space tethered system parameters, which provide safe space debris towing after its capture by the harpoon. The mathematical model of described system was developed. The model accounts for of the towed object rotation around its center of mass and the possibility of the tether slack. The disturbances occurring from the harpoon impact on debris were identified for the worst case, when the harpoon enters the most distant point from the space debris center of mass. Border values of towing system parameters, ensuring safe capture and following space debris removal, were obtained by numerical simulations series. It was shown that in case of a low thrust of the tug, the system rotation could result in its transition into a chaotic mode. In case of a high-thrust, the towed object may start rotating due to the harpoon impact and a periodic disturbance of the elastic tether. The results of this work can be used for new space systems for space debris de-orbit design. | ||
Gidaspov V. Y., Moskalenko O. A. Numerical simulation of detonation initiation in a kerosene-air gas-droplet mixture impinging shock wave. Trudy MAI, 2016, no 90, http://mai.ru//upload/iblock/6b1/gidaspov_moskalenko_rus.pdf The paper studies the process of detonation initiation of a of gas-droplet kerosene-air mixture incidental shock wave in a shock tube. A simplified physical-mathematical model of the process was developed. Drops of hydrocarbon fuel are considered as a single component of fuel droplets evaporation and gas-phase chemical transformations. The paper focuses on mass fraction droplets in the processes of detonation wave formation and propagation in the channel. The authors propose consistent methods of recovery according to the reference data on the thermal part of the Gibbs potential of gasoline, kerosene and diesel fuel in liquid and gaseous states. The results, obtained by numerical simulation time scanning process, encompass the following:
By computation, we found and observed experimentally two fire-ignition modes of the combustible mixture. | ||
Larionova A. A., Dudchenko A. A., Sergeev V. N. Mechanical design of components composite-metal connections. Trudy MAI, 2016, no 90, http://mai.ru//upload/iblock/e2e/larionova_dudchenko_sergeev_rus.pdf In this article considered method of analytical solution by determine parameters the transition zone of the wing joint for transmission of load from the composite to the metal. The developed method allows determine efficient length of transition seam zone, which depends on the value of loads, the diameter of the bolts, and material of composite and metal. First of all, it is determined by the length of the inclusion zone. Then, it is determined by the required number of rows for fasteners, depending on the diameter of the bolt or rivets. Mechanical connections have a significant disadvantage associated with the drilling of holes for bolts or rivets, which leads to cutting fibers, stress concentration at the site of setting bolts and weakening of the strength and rigidity of the construction at this location. However, thanks to good strength and stiffness characteristics with low weight, the composite material (CM) are used in load-bearing structural elements of aviation and space technology.
Results were obtained in carrying out the work:
It shows good agreement between the calculation results. | ||
Golovkin M. A., Golovkina E. V. Flow Structure Visualization nearAircraft Models in Low-Speed WaterTunnel (Aircraft Aerodynamic Configurations). Trudy MAI, 2016, no 90, http://mai.ru//upload/iblock/618/golovkin_golovkina_rus.pdf Results have been given of a flow structure visualization in the neighborhood of a number of models of aircraft, such as MiG-23, MiG-29, Su-27, «Buran» orbital vehicle, delta-winged and forward swept wing aircraft models, and the models with intakes mounted on the upper surface of lifting body. The investigations were intended for revealing specific features of flows and vortex structures generated during flow over aircraft elements. Model tests have been performed in TsAGI HT-150 and HT-400 very low-speed water tunnels (flow velocity of ) wherein the velocity is formed by the gravity of water flowing out from the large container disposed above into the working section. Flow visualization was accomplished by the method of colored jets. Colored liquid in the form of aqueous solution of aniline colors was fed to the model inner cavities through the sting «by gravity» due to altitude difference from containers disposed by ~3 meters higher the model level. The liquid flowed out through the drainage pinholes on the model outer surface and drifted by approach flow tangentially to the surface of the aircraft model. When required, the visualization of external flow was carried out using streamlets flowing out from the «comb», the thin tubes positioned upstream in front of the model. HT-150 water tunnel was equipped with the mirrors located on the right and on the left of its working section, which made it possible to take views or carry out video filming of three model projections simultaneously. As a result of the conducted investigations some specific features were revealed of flows and vortex structures generated during flow over a number of aircraft models. Visualization of flow over the MiG-23 aircraft model at a sweep angle χ=47°of wing outer panels at the leading edge showed that in the presence of sliding at the angles of attack α above 17° the windward vortex core generated by confluence of forebody and wing extension vortex cores, approaches the vertical tail and passes above it. Due to the strong downwash induced by the united vortex core in the vertical tail region, the rolling and yawing instability of the aircraft model develops. The leeward united vortex core shedding from the forebody and wing extension propagates along the right wing outer panel, which causes the still greater development of rolling instability at these angles of attack. As a consequence of the investigations on visualization a mechanism of yawing and rolling stability loss of the MiG-23 aircraft model confirmed in wind tunnels was revealed and the original ways of improving these aerodynamic characteristics were found. Visualization of flow structure on the MiG-23 aircraft model with a sweep angle χ=74° at the leading edge of wing outer panels showed that the above-mentioned united vortex cores (windward and leeward ones) descend in the tip wing sections and pass at a considerable distance from the vertical tail. Therefore, the noted above degradation of lateral static stability characteristics for the model with χ=74° did not occur, that is confirmed by wind tunnel tests. Investigations of flow structure in the neighborhood of the delta-winged model showed that the vortex cores generated nearby the wing leading edges slightly rise from the tip chord of vertical tail. In the presence of sliding the vortex structure is not as much skewed as in case of the MiG-23 model with χ=74°; as a result, one might expect that the lateral characteristics of such model must be satisfactory. Visualization of flow over the forward swept wing model has revealed the following flow features. Tip vortex cores of the wing can be plainly seen. Due to |