Bibliographic references

Khatuntseva O. N. Is the dynamic chaos a stochastic process in the autonomous systems of differential equations of the Lorenz system type. Trudy MAI, 2020, no 112,

At present, there are no stability criteria similar to Courant-Friedrichs-Lewy criteria for systems of autonomous differential equations (SADE). The instabilities, manifesting themselves as a computational chaos, occur while the numerical integration of SADE. Moreover, the time step decrease does not lead to this instability elimination. Commonly, the studies on determining the sensitivity of solutions to the initial conditions setting are being conducted to explain the deterministic chaos phenomenon. These studies demonstrate exponential divergence of initially close solution trajectories, and impossibility of selecting such small computational error to «conquer» the uncertainty in the Lorenz type SADE.

The conclusion is drawn from this circumstance that since the principal difficulties do not allow achieving the necessary accuracy, there is no need to muse about determinism. However, such approach does not resolve the problem of solutions determinism, irrespectively to the possibility or impossibility of obtaining of the information regarding the evolution of the considered system. The issues of predestination in the closed systems, in particular with such closed system as Universe, conjugate with these issues.

The studies conducted in the presented work demonstrate that the deterministic chaos occurring in SADE of Lorenz type may be associated with the stochastic process and is not, in essence, the deterministic chaos for any finite time step.

The article discusses the issues associated with the possibility of turbulence modelling based on the Navier-Stokes equations via direct numerical simulation technique.

The problems related with the feasibility for modeling of the turbulence on the basis of Navier-Stokes equations via the direct numerical simulations are also addressed in the paper.

Baklanov A. V., Krasnov D. S., Garaev A. I. Studying parameters of combustion chamber section with jet-injection nozzle. Trudy MAI, 2020, no 112,

Pressure losses, combustion completeness, temperature field unevenness at the outlet and hazardous substances release are one of the main parameters of a combustion chamber. The article presents a fuel combustion technique, in which an air jet is fed along nozzle axis, and the fuel is being inserted into the main flow by means of the radial trickles. The effect of the jet-injection nozzle setting into the combustion chamber section on the above listed parameters changing is being considered to estimate this fuel burning technique. The structure of the bench installation for the combustion chamber section testing, as well as modes at which these tests were being conducted are presented. Equipment, employed for measuring such parameters as flame temperature and concentration of hazardous substances in combustion products was described as well. To perform analysis and comparison of the obtained data, the experiments were conducted with the jet nozzle and the jet-injection nozzle being installed into the combustion chamber section in number of nine pieces. The section represents the 1/14 of the full-sized combustion chamber and consists of the outer and inner cases, and a flame tube with the with a frontend device, in which the nozzles are being installed. The flame tube is bounded by the side cooling walls on both sides. Nine nozzles are being installed in the section. Analysis of the component content (CO, NOx, CH) and combustion products was conducted, and combustion completeness was computed according to the obtained data. From the analysis results the inferences were drawn on the jet-injection nozzle application efficiency, and recommendations were given on the nozzles of selected type installation in the full-sized combustion chamber.

Budanova S. Y., Krasavin E. E., Nikitchenko Y. A. Navier-Stokes-Fourier model options for supersonic and hypersonic flows. Trudy MAI, 2020, no 112,

The flows of the high-degree non-equilibrium are of considerable interest at present stage of the engineering development. Such flows are being realized, for example, while the hypersonic flying vehicles flow-around, reentry spacecraft, in vacuum installations and other technical devices.

The basic physico-mathematical model of a gas medium flow is the Navier-Stokes-Fourier (NSF) model. This model is theory-based for weakly non-equilibrium flows, but it can be applied for the flows of a high-degree non-equilibrium. In such flows, the NSF model coarsens the solution. For example, when computing shock waves, the disturbance area is narrowed. The model is short of viscosity. The opposite sign effects are being observed while the gas intensive expansion.

The presented work analyses the processes of the non-equilibrium stresses and heat flows forming at the shock wave front, employing the model kinetic equation (MKE). The hypersonic flow at the Mach number of M= 5 is under consideration.

The article shows that the heat flows gradients, absent in the NSE, contribute mainly to the non-equilibrium stresses forming process. The basic factor of the heat flows development are the fourth-order gradients, which are missed in the model as well.

Several options for improving the viscous properties of the NSF model are under consideration. It is known that in the case of multi-atomic gases a significant effect can be achieved by accounting for the voluminous viscosity in the equations of non-equilibrium stresses. Besides, the voluminous viscosity coefficient allows computing the temperature of the translational degrees of freedom molecules in the first approximation. Defining the shear viscosity coefficient by this temperature, will improve the viscous properties of the model.

The Stokes’s friction law can be obtained by using the moment stress equation as its strict first approximation. If one accounts for the terms of the second order of vanishing in the equation terms, containing gradients and divergence of the flow velocity, , then the shear viscosity coefficient will take a tensor form. The NSF model with this shear viscosity coefficient describes better the processes of viscosity and heat conductivity.

The article demonstrates that the improved option of the NSF model allows obtaining rather wide area of disturbances on the example density, velocity and temperature profiles in the flat shock wave. The profiles shapes differ slightly from real ones. This, probably, is a consequence of the artificial approach to the model improvement.

Duong M. D., Gidaspov V. Y. Computational algorithm for calculating composition of combustion products of hydrocarbon fuels in the presence of a condensed phase. Trudy MAI, 2020, no 112,

The article describes the computational algorithm that allows computing the equilibrium composition of combustion products of hydrocarbon fuels in the presence of condensed components. The mixture of combustion products was considered as an isolated system of ideal gas without energy interaction and mass exchange with the environment. Numerical methods and computational algorithms, based on the thermodynamic potentials extremum search, are employed for the thermodynamic equilibrium search. The composition of the combustion products of hydrocarbon fuel in the air may include about 150 possible compounds of chemical elements C, H, O, N, Ar, with condensed phases of C(с) and H2O2(с) among them. The article presents specifics of the algorithm implementation with regard for thermodynamic functions at the temperature of the phase transition Tp.

Without this, in many cases, when the temperature value passes through the point T= Tp, the monotonous iterative process is disrupted, which may lead to the algorithm divergence. The results of numerical simulation of stationary equilibrium flow of combustion products of kerosene with the air in a Laval nozzle are compared with reference data. The effect of pressure on the composition of combustion products in excess of fuel was studied. Analysis of the computational results and reference data confirms the reliability of the developed algorithm. The impact of pressure (p = 1–100 atm) on the composition of combustion products in an adiabatic reactor with an excess of fuel was studied. It follows from the obtained results, that the condensed phase (p = 1–100 atm.) is a part of the combustion products at the air excess coefficient α < 0.36, the dependence of the soot concentration on the pressure changes qualitatively with the air excess coefficient changing.

Selim R. S. Eigenvalues of the Squire equation for laminar and developed turbulent boundary layers. Trudy MAI, 2020, no 112,

The stability of the eigenvalue problem for two-dimensional laminar and turbulent external flow over a flat plate was numerically studied using the theory of time linear stability. That is, the classical as well as the efficient approach are considered in detail for the eigenvalue problem: two different methods are studied for deducing the spectrum of eigenvalues, namely the finite difference method and the collocation method based on basic functions. The first approach of the physical model discretizing leads to algebraic equations with large matrices that are difficult to solve efficiently, while the second one creates matrices that are usually complete and have a large number of conditions. This problem is being discussed here in the Appendix to the Squire equation, which describes laminar and turbulent boundary layers. The average velocity profile of laminar boundary layers is obtained numerically. The dispersion ratio as a function of the wave number α and other flow parameters for the problem (such as, the Reynolds number) is being defined for two different velocity profiles. The algorithm is realized in Mathematica, and the calculated eigenvalues are being compared between the two different methods.

The linear stability of a small class of engineering problems can be studied by solving the Orr-Sommerfeld equation. The most famous examples of this are the Blasius Boundary layer and the plane of the Poiseuille flow. While the plane flow of the Poiseuille is strictly parallel, in the first case, an irrational argument relative to the parallel mean flow must be called in, in such a way that the system of stability equations, obtained by substituting small wave-like perturbations in the Navier-Stokes equations and linearization of the Blasius profile, will be reduced to the Orr-Sommerfeld equation. A numerical method for solving the Orr-Sommerfeld spectral equation in a two-dimensional boundary layer (β = 0) was studied by the Chebyshev collocation method for laminar and boundary layers. To obtain the spectrum of eigenvalues of the Squire equation for the background field of a developed turbulent boundary layer, a collocation method (pseudospectral) based on Chebyshev polynomials was used. The technique was debugged on the profile of Blasius and Mucker. It is obvious that an increase in the number of Chebyshev polynomials has a significant impact on the accuracy of determining eigenvalues for the Blasius and Miskeg profiles. The impact of Chebyshev polynomial degrees on the accuracy of determining the real and imaginary parts of the eigenvalues of the first mode for laminar and turbulent boundary conditions was considered.

Krioukov V. G., Abdullin A. L., Nikandrova M. N., Gasilin V. V. Generation of reduced reaction mechanisms for heterogeneous flows in nozzles. Trudy MAI, 2020, no 112,

Mathematical modeling of chemically non-equilibrium heterogeneous flows in nozzles of both solid engines and direct-flow engines with solid fuel is an urgent task of rocket engine theory. Such flows have a significant fraction of the condensed phase (possibly variable along the length of the nozzle), and are being initially described by huge reaction mechanisms. These features prevent the nozzle problems solution in a modern multidimensional formulation. These predicaments are being overcome in this article in two ways:

a) The condensed phase is being imitated by the “Large Molecules”, which allows consider it a gaseous substкance and include reactions with its participation in the initial reaction mechanism.

b) The initial mechanism is a priori redundant and includes many reactions that exercise minimum impact on the composition of the working fluid. They can be excluded practically without loss of accuracy in the characteristics computing. For this, various methods for reactions reduction can be used.

The presented article proposes a reduction procedure, consisting of two methods: DRGEP (Directed Relation Graph Error Propagation) and a method of linking with an adaptive threshold. The DRGEP method is focused on searching and removing from the reduced reaction mechanism only the substances with reactions engaging them. If insignificant reactions still remain in the mechanism, they are removed by the engagement method. The degree of the mechanism reduction depends on the reduction threshold ζL. The developed procedure requires a small amount of calculations and allows reducing the initial mechanism to a certain acceptable size, ensuring a controlled error in predicting the flow characteristics.

This procedure was applied to the task of reducing the reaction mechanism in the stream of combustion products of metallized fuel C + O + H + N + Al + Cl. The initial reaction mechanism included 33 substances and 68 reactions. The reduced mechanisms were generated at various thresholds of value of ζL = 0.02–0.12. For small ζL values, the reduction rate is = 5.0–6.5 with high accuracy in the flow characteristics predicting. Further, with an increase in ζL, the indicator increases significantly, but forecasting errors significantly rise. In the presented example, the most acceptable mechanism was generated at ζL = 0.08.

Popov V. V., Sorokin F. D., Ivannikov V. V., Degtiarev S. A. Developing a spatial model of a gear transmission with separate storage of the accumulated and extra turns for solving non-linear problems of aviation transmissions dynamics. Trudy MAI, 2020, no 112,

Aviation transmissions ensure the torque transfer from the rotor to propeller or fan, and accessory box drive in the engines of various types, from the engine to the shaft of the main and tail rotors of the helicopter etc. [1-3]. Aviation transmissions should ensure high strength properties at small size. The dynamics analysis performing seems to be the best tool for these requirements compliance ensuring.

Many scientific papers deal with the gear transmission dynamics. The most meaningful and interesting gear transmission models are represented in the works of Cardona [9], Spitas [12], Qiu [13], Margielewicz [14], and Kubo [19]. Nevertheless, most of them do not account for the linear wheels movement, variable stiffness, interaction between gears and other machine elements, and unfit for the non-stationary dynamics studies.

The article presents a spatial model of the gear transmission capable of accounting for the aforementioned limitations and applicable for the non-stationary dynamics problem solving. The model is based on the Cardona’s model [9].

The model employs Euler vector and the rotation tensor associated with it as rotations description. The final rotation is being decomposed into the accumulated rotation and a small incremental one. This technique allows avoiding the problems associated with achieving exceptional points near the 2p angle [15-17].

The presented model can be employed for performing analysis of the wide spectrum of gear transmissions, such as spur gears, helical gears, conical gears and internal gears. The model allows accounting for the gear mesh stiffness, gear mesh damping, kinematic error of the transmission and backlashes. The gear transmission model can conjoin with the models of other machine elements such as shafts, bearings, cases etc.

The proposed model was verified by several well-known tests.

Yudin D. A., Firsanov V. V. Computational and experimental study of the strain-stress state of product structural elements at the impact against a solid obstruction. Trudy MAI, 2020, no 112,

The article presents the results of computational and experimental study and mathematical modelling of product structural elements while the impact with the solid impediment. The problem of developing effective technique of numerical modelling of three-or dimensional dynamic impact problems.

The finite element method was used for the impact problem solving.

The results of strains and stresses computing were compared, using numerical modelling, with the results of the full-scale test, which demonstrated their validity.

The impact load tests are an obligatory part of the general complex of preliminary field tests of the prototypes of engineering products at the experimental development stage. The basic requirement to the field tests consists in ensuring the equivalence of the impact loading under the field conditions of the product loading while operation.

The validity of the impact loading tests ca be increased by improving testing and measuring equipment, as well as testing technique due to determining impact loads as close as possible to the operational ones.

To reduce the volume of the cost intensive field tests of the products, they are being replaced by mathematical modelling with modern software. The basic requirement for numerical computations consists in ensuring the equivalence of the impact loading while mathematical modelling to the loading under conditions of the field tests. Usually, the correspondence of the testing modes on the velocities and impingement angles, as well as overloads levels in the characteristic zones of the structures are being accepted as the equivalence conditions.

Timoshenko A. V., Koshkarov A. S. Comparative analysis of entropic metrics of space objects optical images informativity. Trudy MAI, 2020, no 112,

The existing tendency to the intensity increasing of near-Earth space employing by ever-increasing number of states, expanding spectrum and increasing complexity level of the space operations, the expected deployment of the extra-large satellite systems for group space missions are increasing the risks for the space activities associated with technogenic contamination. Optical images are the most informative type of information on the situation in outer space. The article brings up issues concerning preliminary images rejection obtained by the ground-based optical means, unfit for the human operator recognition. Specifics of the space objects surveillance by the ground-based optical means with account for dangers for national space vehicles and manned flights safety are considered. Estimation of the conventional network of optical means is performed. The necessity of performing preliminary rejection of the images, being obtained, prior to the analysis performing by the human operator is substantiated. It is shown that the main post-detector processing method is blind deconvolution of images. The work with the functional of the entropy of the image being restored is required while deconvolution operations performing. Entropy metrics by Shannon, Tsallis, Capture and Rennie were selected for the study. A comparative analysis of the entropy metrics of informativity, which application is in demand when computing the deconvolution functional, was performed. Test images with different visual quality were selected. On the example of real images a possibility of their employing with account of images visual perception by the human operator was estimated. Within the framework of the conducted studies inferences were drawn on the applicability of employing various entropy metrics and the degree of their consistency with the structural-semantic approach of visual perception of images by a human operator. The trends of future studies on determining the generalized metric for the images of such class, as well as applicability of entropy metrics to the processing satellite-obtained data on the remote Earth monitoring were determined.

Gusev S. N., Miklin D. V. Model of the test radio signals simulator for aviation systems of the Earth surface surveying . Trudy MAI, 2020, no 112,

The article presents description of the model of the test radar signals simulator designed for calibration problems solving of air borne synthetic aperture radar systems (SAR). Control algorithms, employed in the simulator, for forming simulating trajectory signals, which reproduce virtual objects on radar images, are being considered as the subject of the study.

The necessity of solving this problem is stipulated, firstly, by the complexity of SAR calibration for complex objects, employing calibration polygons; secondly, by the lack of a uniform approach to the calibration means development based on simulators, employing the retranslation principle of the SAR probing signal. Thus, the purpose of the article consists in developing a model of the test radar signals, allowing reproducing the target environment with the specified set of object of various structure on the radar.

The proposed model is based on application of the theory of spatial and temporal signal processing in SAR and computer modelling techniques, from which the viewpoint the target simulating trajectory signal is the sum of the reflected signals from the point reflectors in a complex concentrated target. Each echo signal from the point reflector herewith should be computed with account for the position and the nature of the reflection in the specified direction.

The developed model peculiarity consists in frequency correction procedure integration into the algorithm for simulating trajectory signal formation. It allows compensating the geometry violation of the wave front and the change in Doppler frequency spectrum, caused by the objects reproduction at the certain distance from the simulator location.

The result of the work represents the model structure of the test radar signals simulator and the algorithm used in the model for computing the simulated trajectory signal of a complex concentrated target with account for the time delay, amplitude and frequency correction.

The developed model was tested while seminatural simulation of the reproduction process of virtual objects on radar. The seminatural simulation results presented in the work proved the approach correctness and the adequacy of the developed model.

The proposed model can be employed at:

– SAR calibration at different stages of development and design;

– developing of simulators for the signals programming;

– substantiating the trends of methods and means developing of radar systems calibration for the Earth’s surface observing.

Kartukov A. V., Merkishin G. V., Nazarov A. N., Egorov V. V. Object images employing for air medium parameters analysis near moving objects. Trudy MAI, 2020, no 112,

The tasks of monitoring, position assessing of the aircraft and interacting with the environment are of great importance in the aviation technology. At large distances, they are being solved mainly in the radio range (radar). At short ranges, the optical range methods are very effective near aircraft, since the wavelength is several orders of magnitude smaller and allows one to achieve high accuracy of the measured parameters.

Movement of various objects, such as a car, and plane, or a helicopter, is accompanied by their interaction with the air. The aerodynamic parameters of an object are necessary for calculating its speed characteristics and determining the possibilities for their improvement. Typically, the aerodynamic characteristics measurements are performed in wind tunnels employing the reduced models of the objects. The wind tunnel has a rather large and complex structure, requiring highly qualified service.

Registration of the aerodynamic parameters of the air medium occurring while the object moving is possible. Similar methods are used for the fuel quality analysis.

Employing the object images distortions allows obtaining all necessary information on the air medium parameters as well as the «clean» sky turbulence by relatively simple technical realization.

Further, a new technique for the fast and qualitative estimation of the moving object aerodynamic properties by distortions of the reference object image under the action of the turbulent wake. A set of reference objects installed along the path of movement allows determine the size of the turbulent wake, the impact of the structural elements of the object and evaluate their role in creating aerodynamic drag.

The illustrations to the article show the effect of a turbulent wake after a car travels on an image of a straight rail mounted on a track of movement. The white rod image blurred in its lower part, which is stipulated by the laminar layer transformation into the turbulent, is shown as well.

  1. Analysis of the results of the described experiments allows asserting that the electromagnetic waves of the optical range are sensitive enough to inhomogeneities of the air medium and can be used to obtain information on the “moving object-medium” system.

  2. The presented technique can be applied to analyze the aerodynamic parameters of new structural elements mounted on a moving object, without employing complex and expensive equipment.

Compared to the known technique of wind tunnels application, the described technique:

1) does not require manufacturing of a high-precision model of the object being studied;

2) does not require highly qualified servicing;

3) in some cases, an experimental study is possible, wich cannot be implemented in a wind tunnel (for example, for a helicopter);

4) does not require presence of the fastening and information retrieval elements in the working area, distorting the flow;

5) allows building 3D models of the “atmosphere-object” structure using a set of reference rails.

Romanov A. M. Accuracy Estimation and Synthesis of Nonlinear Direct Mathematical Operations on Bitstreams. Trudy MAI, 2020, no 112,

Field programmable gate arrays (FPGA) are widely used in the aerospace industry, both for on-board devices and ground equipment. This paper is devoted to accuracy estimation and synthesis of nonlinear direct mathematical operations on bitstreams (DMOB). DMOB or direct processing of sigma-delta modulated bitstreams is a promising method to reduce the resource area consumption of the FPGA designs which allows to implement complex digital signal processing algorithms on the basis of radiation-resistant FPGAs as well as FPGAs produced by Russian vendors, the logical resources of which are significantly smaller than those of foreign counterparts in commercial versions. The estimates of nonlinear DMOB accuracy which were previously obtained were empirical and covered only a small set of mathematical operations in a limited range of possible implementation parameters. This paper proposes a new approach to accuracy analysis and synthesis of nonlinear DMOBs which allows to implement a wide range of nonlinear digital signal processing algorithms directly on sigma-delta modulated bitstreams providing a given accuracy. The key point of this paper is that nonlinear DMOBs implemented by combining input averaging filters and nonlinear mathematical operation perform linear interpolation of this mathematical operation, and the number of interpolation reference points depends on the filter window. This statement supported by a number of assumptions is analytically proved for a one-dimensional case, and it is experimentally confirmed with regard to a multidimensional case. All the assumptions used in the proof are analyzed in detail, and the conditions of the proposed method of applicability for real projects are formulated on the basis of the assumptions. Solutions described in this paper allow to achieve a flexible compromise on the nonlinear DMOB FPGA core area usage and the computation accuracy. The example of the implementation of bitstream multiplier demonstrates that the proposed solution is superior to the previously known and widely used analogue.

Radin D. V., Makaryants G. M. Developing and experimental studying of dynamic characteristics of adaptive pressure pulsation dampener for the gas turbine engine fuel system. Trudy MAI, 2020, no 112,

One of the key trends for the environmental and cost performance improving of modern gas turbine engines is the development of low-emission combustion chambers, which realize the concept of lean homogeneous mixture combustion. Pressure pulsations in the gas turbine engine fuel system can lead to unstable combustion in low-emission combustion chamber. The pump rotation frequency varies greatly depending on the engine operation mode. Thus, it is necessary to employ the adaptive Helmholtz resonator, being adjustable to the pump rotation frequency, to suppress the pulsations. In the work being presented, the adjustable element of the dampener was represented by the cavity volume. This study focuses on the developing and experimental studying of dynamic characteristics of the adaptive resonant-type pressure pulsations damper in the frequency range under consideration., An automatic design system was developed in the C# programming environment to perform theoretical studies. The experimental test bench consisted of a pump, a fuel cooling system, a resonator with a piston to change the cavity volume, and the imitation the fuel system. The pressure pulsations prior to and behind the resonator, as well as behind the pump, when the resonator was not installed, were being measured while testing. The resonator volume was being varied from minimum to maximum value. The efficiency of the adaptive Helmholtz resonator was being evaluated with the insertion attenuation factor, which represents the ratio of the pressure pulsations amplitude in the circuit without resonator to the pressure deviations amplitude in the circuit with the resonator. The frequency characteristic of the adjustable resonator efficiency represents the monotonically decreasing curve. The efficiency of the adjustable dampener increased by more than three times at the subresonant, and by more than half times at the superresonance frequencies compared to the non-adjustable one. The experimental data verified the theoretical computations with high accuracy. The adjustable Helmholtz resonator ensures much higher pressure pulsations damping than the non-adjustable one in the entire frequency range.

Efanov V. V., Zakota A. A., Volkova A. S., Izosimov A. V. The aircraft weaponry control technique in conditions of covert target surveillance. Trudy MAI, 2020, no 112,

The military aircraft weaponry includes both guided and unguided weapons, radar and optoelectronic surveying-and-guidance complexes intended for striking both air-born and ground targets and ensuring aircraft defense.

There are known technique and devices for aircraft weaponry control, which perform the target detection and capture, determine its parameters, choose the weapons and perpetrate its preparation and launch.

The disadvantages of the above-described systems consist in the fact that the weapon control in conditions of the covert target surveillance is not being ensured.

Selection of the channel with the passive type radar means as a leading channel of the weaponry control system ensures discrete operation mode for the active type radar means of the slave channel of the weaponry control system. The mode of periodical measuring of the range on target herewith, being followed by the radar means of the leading channel of the weaponry control system, with transition to the continuous position finding at achieving the preset range or by the crew command. It ensures the possibility of covert target attacking at its capturing.

Identification of the targets being followed by the radar means of both leading and slave channels of the weaponry control system is performed, in the absence thereof the reset mode of capturing by the radar means of the slave channel of the weaponry control system is set. By this, the probability of the target tracking and the aircraft interference immunity is increased.

Targets identification is realized by comparing the absolute value of the angular coordinates difference of the target viewfinding by the radar means of the leading and slave channels of the weaponry control system with the preset threshold. With this, exceedance of the above mentioned threshold is conceded only during the set time interval.

The stealthiness of the passive radar stations operation ensures higher viability under combat conditions due to the hampering of their detection and jamming.

However, unlike the active detection and ranging, active detection and ranging does not allow obtaining the object range by the data of receiving signas from the single station. This is undoubtedly a serious disadvantage.

Analysis of the methods ensuring indirect determining of the targets’ range and motion speed was performed. It is necessary to utilize the joint results of several (more than two) tracking stations, removed from each other by the known distance, and any of the

The kinematic distance measurement method (KDMM) being used while working with only a single target is known. The KDMM is realizing one of the information restoring methods, and it comes into action if other information restoring techniques are unavailable. The information about a target is being by the angular coordinates in the vertical or horizontal planes with the supporting height. The results of the KDMM modeling show that the absolute error of distance measurement makes up from hundreds of meters to several kilometers.

The purpose of the work is consists in accuracy increasing of the the range and speed of aerial target movement determining in the covert surveillance mode.

To eliminate the KDMM shortcomings the method of covert determining the target motion parameters is proposed. Its essence consists in obtaining the target motion parameters based on solving the vector equations that associate the range, speed, and bearing of a fighter-interceptor with a target. To obtain herewith the parameters necessary for the equations solving the interceptor should perform certain maneuvers.

The modelling results analysis of the proposed method and algorithms realizing it allows making the following conclusions:

— the method ensures the much more accurate distance-to-a-target computing;

— the maximum error value is below the resolution range level of the onboard distance measuring devices.

The suggested algorithms for determining the target range and motion speed are approved with the semi-natural complex composed of the thermal direction finder, target simulator, microcomputer, interface with the personal computer, and the programmed-mathematical support.

The technique for evaluating the effect of measuring resolution of the track angle, flight-path angle, and velocity variation dynamics on the target motion parameters determining accuracy is suggested.

While semi-natural tests conducting it was determined that the suggested technique and algorithms are efficient in general. Practical computations on determining the range to a target demonstrate that the errors introduced by the computing process significantly increase, if the Gauss method is being used for the task on the forward motion and the rational selection of the reference element is not accounted for. At the same time, the instrument errors impact can be significantly reduced by the reference element rational selection at each step.

A technique for target detection was suggested for the case of decoy flares employing. The technique consists in

– the airborne target detection,

– selection of angular speed of optoelectronic module (OEM) guidance by the crosshair superimposition on the target on the screen,

– transferring the OEM to the automatic target guidance mode,

– measuring current target range,

– converting the digital code of range into the video signal, displayed of the screen in the form of the digital caption.

The following factors are additionally determined:

– angular velocities of the target motion by measuring the time intervals of the target shifting relative to the preset angular positions;

– angular accelerations of motion by evaluating dynamics of the target angular velocities;

– dynamics of angular accelerations changing by subtracting the subsequent and previous values of the angular accelerations of the target.

With this, the following factors are recognized:

– the target tracking, if the values of change in dynamics of the angular accelerations of the target motion are less than the set value;

– the decoy flare tracking, if the values of change in dynamics of the angular accelerations of the target motion are more than the set value.

In this case a man-portable weapon complex gunner receives the information capturing the decoy flare.

Dmitriev V. I., Zvonarev V. V., Lisicin Y. E. Justification technique for rational control methods of unmanned flying vehicle. Trudy MAI, 2020, no 112,

The purpose of the article is efficiency increasing of the unmanned aerial vehicle (UAV) application based on the feasible selection and realization of rational control method.

The article considers the UAV application as the object of research. The subject of research is the UAV control methods.

The relevance of the topic in the modern military-political situation is determined by ensuring the State security in the field of military development, on the assumption of the existing threats. At present, UAV is the most important component of weapons, military equipment, automated reconnaissance and information transfer systems. Its application can significantly increase the efficiency of troops command and control, increase combat capabilities and combat means effectiveness.

The article presents a methodology for the UAV application effectiveness evaluating and a technique for the UAV control methods forming. The dependence of the orrect frame reception probability on the signal-to-noise ratio for a system with addition and with auto-selection is demonstrated. Recommendations on the UAV control method selection are given.

The practical significance of the article consists in the following:

– the developed technique for evaluating the UAV application effectiveness describes more accurately the conditions for receiving messages and allows compare radio channels with various characteristics (type of modulation, type and parameters of the noise-immune code, etc.) at the information receiving point, and perform the performance indicator computing of the UAV control methods;

– in supplement to the known methods, the developed technique for rational UAV control methods substantiating allows accounting for the dynamic characteristics of a random process, determine the exact parameters of the radio channel, and increase the reconnaissance depth (ensuring herewith the required survey resolution of the required probability of the correct frame reception and the given stealth).

It is advisable to use the obtained methodology when planning the use of UAVs with the aim of transmitting information over the radio channel with signal fading.

Philatov V. I., Bonch-Bruevich A. M., Khokhlachev E. N., Borukaeva A. O., Berdikov P. G. Parameters formalization of adaptive protection system for automated communication control system. Trudy MAI, 2020, no 112,

The article analyzed the theoretical model of the system for protection of the automated communication control system (AССS) against accidental hazardous impacts, representing a threat to the aircraft control systems. The tasks for realizing systematic approach to solve the problem of ensuring the ACCS adaptive protection.

The simulation model for the AССS protection against hazardous impacts, employing the queueing theory, is considered. The article analyzed the properties of simulation modelling systems, namely GPSS World. The article presents also a mathematical model of the protection system and reviews the functions of its components.

The article used Kendal-Basharin representation for formal presentation of various options of the AССS protection organization against hazardous impacts. Model restrictions, which represent a function of loss for the untimely users requests compliance were considered

The task of the most rational organization of the ACCS functioning was put forward in the article.

From the performed analytical work the inferences were drawn that it was not rational to use the method of simple sorting of all possible options to obtain the optimal option of the ACCS adaptive protection system. There is a necessity to employ a combined algorithm of the directional search with the penalty of randomness together with static tests.

The topic of this work relevance is stipulated in the first place by the necessity to develop new methods and ways for the ACCS protection from the hazardous impacts, used for the aircraft control, for example, in case of the control interception prevention.

Lebedev A. S., Dobrolyubov A. N., Mikhaylenko A. V., Bezrukov A. V. Searching for diagnostic features for controlled surfaces contamination recognition system at the optoelectronic monitoring. Trudy MAI, 2020, no 112,

Anan’ev A. V., Rybalko A. G., Lazorak A. V. A technique for target run-in direction justification based on theory of risk when striking ground-based objects by aircraft complexes. Trudy MAI, 2020, no 112,

This technique allows performing application planning of:

- The new military-purpose complexes, namely, small-class unmanned aerial vehicles (UAV SC),

- New weapons, such as free-falling unguided containers (FFUC), charged with the small caliber and capacity ammunition for damage inflicting to easily vulnerable ground objects.

The FFUC application specificity is its discharging from the carrier as a large-caliber ammunition, which requires special attention while the targeting point selection. The presence, in its turn, of asymmetrically located and different by their importance elements as parts of the ground target contributes to the several targeting points’ selection and, hence, determining rational direction of the approach.

Thus, for example, when employing large-caliber weapons against long narrow targets, it is necessary to select a certain rational angle of approach. At the same time, if the small-sized ground based objects are being attacked with the weapons, which scattering characteristics do not commensurate with the target size, the approach direction selection makes no difference, and targeting is being performed to the center of a target. The FFUC specifics and scattering parameters allow recognize “an aircraft on the open flying line” as a stretched area-type target with asymmetric location of the unequal by the damage probability and damage-inflicting scale vulnerable areas, rather than a small-sized single ground object.

Thus, the newly revealed property of the object of striking should be accounted for while rational selection of the target approach direction by the UAV CS and target striking by the FFUC.

The gist of the developed technique consists in the following:

- The ground target decomposition on n vulnerable zones, when the areas of these zones fit into the total area of the object;

- Criterion selecting (recovery time of the damaged units of vulnerable zones), and indicators defining (labor costs required to replace units of vulnerable zones) of damage inflicting risk for a ground target;

- Risk weight factors determining for each vulnerable area by the expert assessment method (Thomas Saati hierarchy analysis method);

- Determining probability of vulnerable zones hitting with the FFUC, with account for the targeting point disposition in range and direction, and the UAV SC accuracy characteristics;

- Employing the analytical expression of integral risk (the first multiplier is probability of the FFUC hitting the vulnerable zone, and the second one is the risk weight factor for each zone) for risk value determination when targeting point shifted by one step in range and direction for each iteration;

- Creating three-dimensional dependence (surface) of the integral damage risk on targeting point position on range and direction;

- Selecting rational direction of target approach as the result of revealing several local extremes of the integral risk function.

Thus, the target approach at the angle to the central axis of the ground-based target justified by the proposed technique ensures 20% increase in the inflicted damage compared to the target approach along the central axis only.

Kalyagin M. Y., Voloshin D. A., Mazaev A. S. Quadcopter flight control system simulation in Simulink and Simscape Multibody. Trudy MAI, 2020, no 112,

Currently, the unmanned aerial vehicles (UAV) are widely used throughout the world as means for monitoring, creating maps, optimizing agricultural activities, monitoring fire being dangerous areas, power lines surveillance, logistics, etc. The multirotor-type UAVs are widely proliferated due to their structural simplicity and the ability to both flying at near zero speeds and maneuvering with high frequency.

One of the most important tasks at the early stages of the UAV design consist in studying dynamic characteristics of alternative design options of the vehicles with account for their design characteristics. The state-of-the-art computer engineering systems are able to implement the end-to-end process of designing and linking solid-state UAV models with adaptive dynamic models and their operation in various modes by transferring design parameters obtained in CAD systems, directly to the simulation environment of the flight control systems. Of particular interest is the set of tasks associated with control algorithms developing to ensure the UAV normal operation under the impact of external disturbances.

The article proposes an approach to the solid-state and dynamic computer models linking of the unmanned aerial vehicle of the “quadcopter” type at the early stages of the design using Solidworks and Simulink/MATLAB software packages. The model designed in the Simulink/MATLAB environment allows evaluating the developed systems for an aircraft stabilization and control for the UAV, implemented according to the “quadcopter” aerodynamic scheme without starting the quad copter itself.

The discrepancy between the results of the computer model with full-scale tests is 2.3% for the pitch angle, 2.5% for the roll angle, 6.7% for the yaw angle and 3.7% for the height. The obtained high accuracy of the models conformity proves the possibility of applying the method for the automatic control system designing presented in the article.

Bagrov A. V., Dmitriev A. O., Leonov V. A., Moscatinev I. V., Sysoev V. K. Two-wave optical lunar navigation system. Trudy MAI, 2020, no 112,

The article proposes creation of a global lunar optical navigation system based on light beacons located on the lunar surface, operating at two wavelengths. This system, based on optoelectronic devices on spacecraft and light beacons, will allow obtaining a high-precision navigation system both on the Moon surface and in near-Moon space.

Previous articles analyzed in detail the required number of spacecraft to create a radio-technical lunar navigation system and showed that this would require a grouping of eighteen navigation lunar satellites, and a complex data management system for this structure.

The beacons application allows create a lunar navigation connected system (LNCS) on new principles, which allow doing with a minimum number of navigation satellites. In addition, such system is needed, which can be built-up stage-by-stage from the local system (created for a separate lunar area) to the global one (over the entire lunar surface), and from periodic possibility of the object positioning to the twenty-four-hour one with high measuring operativeness.

The main purpose of the global optical navigation system based on a two-wave system of light beacons, being deployed on the lunar surface, is maximizing accessibility for the LNCS spacecraft in any circumstances. Application of two types of the light beacons, namely ultraviolet and infrared bands will allow observe the reference beacons by the spacecraft from both the Moon orbit and being placed at the Lagrange point. Ultraviolet emitters will allow reduce noises and exposure by the Sun radiation while the beacon surveillance by a spacecraft, while the infrared radiation will be able to pass through the Earth atmosphere for registration by the Earth-based telescopes. The proposed navigation system based on measuring optoelectronic devices located on the spacecraft and light beacons on the objects being positioned will allow high-precision navigation system, which will ensure spatial positioning of the objects on both lunar surface and near-Moon space.

Grigorieva F. L., Khromov A. I., Grigorieva Y. Y. Flat sample stretching in conditions of flat-stressed state at various displacement velocities fields. Trudy MAI, 2020, no 111,

The presented article considers an algorithm for a strip deformation in conditions of a plane stress state, which is represented in the form of the stage-by-stage transition from continuous to discontinuous deformations speeds field. This problem solution is described by mathematical model of a rigid-plastic strip, made from various structural materials. Pre-eminent deformation speeds field is being determined depending on the billet material, which allows determine the process of the material origin and destruction as early as possible. The result of this work is deformation speeds field, as well as optimal E1 value determining, allowing characterize preferable flow selection depending of the material, from which the sample was fabricated.

The article also offers computation of force values, occurring while a flat sample deformation at various stresses values. A possibility of pre-eminent deformation scheme selecting is originating whereby depending on the material, which is used for the sample producing. The plate geometry changing is considered as one of the deformation parameters. Depending on the proposed approach to the deformation state, a stage is selected, at which a flat sample either obtains a neck shape, or is being deformed without it up to the material rupture. To the author’s opinion that this method can be implemented in various fields of aircraft building, machine building, material science etc. Employing the presented approach it is possible to study and obtain deformations of various structures while deforming during operation process, consider critical deformation zones and timely eliminate micro cracks and subsequent material destruction. This approach can be widely applied while examining aircraft skin, engines blades, wheel pairs of the train set etc. The data of the studies can prevent not only damage of various apparatuses, but also catastrophes associated with metal fatigue and destruction of the elements and entire structures. It is micro cracks evolution detection that will lead to optimization and their life span enhancing while of various apparatuses operation.

Nigar E. S. Dynamics of a Plate with Elastically Attached Mass. Trudy MAI, 2020, no 111,

The article regards the problem of a beam dynamic loading by an impact body in the presence of an intermediate damper, namelly, a spring of a given stiffness. The purpose of the study consisted in determining the joint motion of a mechanical system of a beam-spring-body type, neglecting herewith the spring mass. The beam movement is being modeled by the equations of the plate cylindrical vibrations. The obtained equations for the joint movement of the beam–spring–body system consist of equations for the beam deflection and the equation of the body motion, with account for the spring stiffness. The system of equations, modelling the motion, consists of a fourth-order partial differential equation in coordinate, and a second-order equation in time, one of the boundary conditions of which is an ordinary second-order differential equation in time. The problem is solved by the integral Laplace transform method in time. The Durbin numerical method is used for the obtained solution inversion. Graphs of solutions, allowing observing the body behavior and calculating the beam deflection at a time instant, were plotted using this method. The graphs of analytical and numerical solutions coincide for small initial times. The dependence of the sought functions on the main parameters of the problem, such as spring stiffness and the beam bending stiffness, is demonstrated as well. It can be seen from the illustrating graphs that the beam deflection and body motion functions are directly proportional to the spring stiffness, and inversely proportional to the bending stiffness of the beam.

Maskaykin V. A. Theoretical study of temperature regimes when flowing-around axisymmetric bodies being transported on the aircraft external suspension. Trudy MAI, 2020, no 111,

The presented article considers the temperature regimes while flowing-round the transported axisymmetric bodies, which internal temperature is limited. Conditions at which axisymmetric bodies’ transportation happens are represented by the negative ambient temperature and air medium disturbances. The necessity for minimizing the impact of the external ambient effect on the state of the object being transported arises while this problem analysis. The air medium disturbance impact on the object is assumed being in horizontal plane. The set problem was being solved by modelling the solid body flow-around in gaseous medium, including non-stationary heat transfer, employing finite element method. The problem of external ambient static temperature impact was considered to evaluate external factors effect on the axisymmetric body transportation conditions. This problem was solved by modeling non-stationary heat transfer using the finite-difference method. Materials applied in aviation engineering were selected as an axisymmetric body material.

The results of the study demonstrate that cooling time of the axisymmetric body without air ambient disturbance passes faster. It can be assumed that with increasing of the air flow rate, acting on the solid body (excluding the airflow drag effect at a nose portion), its cooling time will be less. Axisymmetric body materials with poor thermal insulation properties compensate rapid body cooling by heat transfer with the external environment (if we consider the temperature regime with air ambient disturbance), in contrast to the axisymmetric body of material with high thermal insulation properties.

Benderskyi B. Y., Chernova A. A. Heat transfer in a rocket engine combustion chamber while geometry changing of the channel-slot solid fuel charge. Trudy MAI, 2020, no 111,

Geometry changing impact of channel-slot charge while its burning on inner-chamber processes execution in flow ducts and pre-nozzle volume of the solid propellant rocket engine are being studied by mathematical modelling techniques. Setting of the conjugate problem of heat transfer in the flow ducts and pre-nozzle volume of the rocket engine combustion chamber with channel-slot solid fuel charge is presented. Numerical schemes and algorithms are being described. Mathematical modelling is being executed based on fundamental system of differential equations of viscous compressible heat-conducting gas movement. In spatial setting, solution of the problem under consideration is performed numerically using finite volumes method with account for the Rhie-Chow correction. The second-order of accuracy counter-flow scheme is employed for inviscid flows discretization, while the second-order of accuracy central scheme is applied for viscous flows. The system of difference equations is being solved by the algebraic net method, and a conjugate gradients method is applied herewith to accelerate its convergence. Various positions of burning dome are being considered while the engine operation at the static section. Profiles of longitudinal velocities components at the charge slice are being compared. The article analyses topological specifics of the combustion products flow, characteristic to various burning dome positions, and singular points are being characterized on the nozzle-cap assembly and near the charge grain-end. Thermal flow density near the structural elements of the combustion chamber is being studied. It was revealed that diameter increasing of the thermal flows channel led to maximum density decrease of thermal flows in the exceptional point and separation zones on the nozzle bottom by 2.04 and 3.6 times respectively. The article demonstrates that with the channel size increase, the decrease of velocity absolute values at the channel cut by 2.2 times is observed. As the result of the inner-channel processes analysis in the pre-nozzle volume of the solid propellant rocket engine, criteria equations for thermal flows evaluation near the exceptional points on the nozzle-cap assembly and the charge grain-end were obtained.

Goldovsky A. A., Firsanov V. V. Impact Interaction Study Algorithms in Aviation Structures. Trudy MAI, 2020, no 111,

The presented article reflects the problem of studying impact interactions in aviation structures. Engineering techniques development on studying the causes of highly-dynamical processes occurrence is a topical task from the viewpoint of application and operation safety of these or that aviation structures. The above appointed techniques are aimed to studying conditions, at which contact interaction of the two elastic-plastic bodies occurs. This article purpose consists in generalizing engineering approach to the processes studying, which could lead to impact process in aviation structures, and it, in its turn, to the hazardous or emergency situation.

Impact interaction of the two elastic-plastic bodies, i.e. internal impact of the metallic plug on the fuselage load-bearing element of the “stringer” type, act as a subject of studies. Due to the contact of the two bodies, stressed-strain state of the load-bearing element is being considered to obtain qualitative estimation of the power factors, impacting on the colliding elements. The article presents the algorithm for studying impact interaction, as well as numerical modelling of the two elastic-plastic bodies’ impact.

Based on the numerical modelling results, operation of the algorithms for impact interaction study is shown, and displacement and deformation values matching criterion in the damaged area nodes was refined.

Bykov A. P., Piganov M. N. Off-line tests technique for spacecraft onboard electronic devices. Trudy MAI, 2020, no 111,

The article presents the off-line tests technique for spacecraft onboard radio-electronic devices. These tests allow accomplishing the ground-based experimental finishing of the onboard instruments. The authors suggest to perform the off-line tests in the framework of the design development test for the samples that passed the acceptance testing. Microprocessor temperature controller was selected as a testing object.

The following test objectives were determined as basic ones:

- substantiation of the samples operability in conditions of external affecting factors imitation close to real ones;

- evaluation of samples correspondence to the design specification and technical conditions requirements on the prime item;

- substantiation of schematic and design solutions for the required liter (0) assigning;

- technological documentation development

- substantiation of the electronic components base and other parts application.

The article describes dedication and structure of the device. The device consists of three identical channels. Each channel contains microcontroller and performs the following functions:

- signals receiving from the contact sensors;

- scanning contact sensors, temperature sensors, and potentiometric resistance transducers;

- receiving eight-bit code from digital sensors;

- forming control instructions;

- receiving “on”, “off” “interrupt” and “reset” instructions;

- forming voted clock pulses;

- performing information exchange through multiplexor exchange channel;

- performing information exchange through RS-485;

- generating telemetric parameters in the parallel code form.

The device is being set on honeycomb panels in the spacecraft non-pressurized compartments. Analysis of technical conditions on the device and previous tests results was performed for the tests modes selection. The technique envisages fourteen types of tests. The study of the tests sequence impact on their efficiency was performed. Selection of both equipment and testing impacts was performed. Algorithm of these tests performing was suggested. Metrological substantiation of the selected test equipment was given.

Tests under normal climatic conditions and rated voltage were being held after the design development test stage completion. Technology trainings were bing performed before acceptance tests.

The authors suggest performing functional test under normal climatic conditions in the following sequence: technical inspection; control of mass; transient resistance measuring; electrical and input circuits check-up; isolation resistance measuring, and functionality check-up in manual mode.

Vibro-bench tests successively in three mutually perpendicular directions are necessary for structural elements resonances detection. Optimal test modes are presented. TV-59349/AIT-440 Vibro-bench was chosen for their realization. Control sensor is being applied to confirm the absence of resonances at the frequencies up to 25 Hz.

The article presents the results of the device testing according to the proposed technique. Comments on design and technical documentation are described. Verification of the test technique, which confirmed the high quality of test algorithm, was performed. Testing time was reduced by 8%. Expert evaluation by the Delphi method revealed that the proposed option of the off-line tests will allow reducing the test cost by 10%. Changes were introduced into design documentation and operation modes chart of electric parts by the tests results. Manufacturing route of the device production was corrected.

Kuznetsov V. S., Volkov A. S., Solodkov A. V., Soroka V. G. Noise-Like Communication System Simulation Based on Simplex Codes Ensembles. Trudy MAI, 2020, no 111,

This article describes a mathematical model of a communication system based on selected signals and architectural solutions. This allows for statistical numerical modeling of both the reference channel with additive white Gaussian noise and real channels selected under conditions. An overview of methods for improving the reception characteristics of noise-like signals and the use of noise-resistant coding methods is given. The issues of creating a system prototype, software development methodology for heterogeneous systems, and debugging and testing of the end device were touched upon. Characteristic of a broadband signal system is being described as stealth, methods for its determining, and an example of calculation for the created communication system.

Communication systems with broadband (or noise-like) signals attract attention of specialists due to the combination of their characteristics such as their ability to operate in conditions of multipath propagation of radio signals, multiple access organizing, etc.

There is a problem herewith of power adjustment (a near-far problem), which is solved by centralized synchronous transmission in the downlink channel from the base station and adjusting the power of the subscriber station transmitters in the upstream channel to equalize the power at the receiving point. In the decentralized mode of operation without base stations, this problem has not been solved, especially at the possibility of subscribers’ mobility. In addition, a system with direct sequence spectrum expansion experiences significant degradation of performance when operating in asynchronous mode, i.e. at random time of transmission of pseudo-random sequences (PRS) in the ether. Communication system organizing possibilities in this case are determined by the cross-correlation properties of the used PRSs, which complicates significantly their search, and often generation and detection.

However, operation of multiple subscribers in the same band and in the same radio visibility zone can be organized by introducing an additional time division by introduction of the expanding PRS. With this, to increase the transmission rate, it is necessary to ensure signals transmission of from one subscriber to several at once, which can be guaranteed only due to the good correlation properties of the expanding ensemble. In this case, a timeslot is allocated to each subscriber in the personnel structure, which is set by a dedicated subscriber station, called a binding station, and a group of PRSs. Radiating to the air several PRSs simultaneously, the subscriber can transmit data to the address of several subscribers. With this, the PRSs discriminability at the reception is ensured by good characteristics of the employed expanding sequences, and the near-far problem does not arise due to the equal signal capacities for different subscribers with their principal equality at the transmission point.

Romanov A. M. Ensuring scalability and specified fault tolerance level of robots control systems. Trudy MAI, 2020, no 111,

The article studies the issue of scalability and fault tolerance ensuring of robot control systems. Based on the analysis of the existing approaches in robotics, a set of techniques is proposed for ensuring the required fault tolerance level, as well as a control system scaling model based on them, which allows employing unified design principles for robots of various sizes and purposes. Creating and scaling robots according to this model allows maximal employing of all previously obtained results, and accelerating creation of the new market-ready products and their upgrade in the future. The model simplifies significantly conversion between various robotics areas including industrial, mobile, aerospace etc. In the course of the conceptual model description the author formulates further trends of research necessary for its realization. The suggested concept fully serves the Industry 4.0 ideology, when specialization of each product with preserving the fast time of its market entry rather than the possibilities of mass serial production, even customized, comes to the foreground.

Timoshenko A. V., Baldytchev M. T., Marenkov I. A., Pivkin I. G. Technique elaboration for various types of sources “suboptimal” monitoring routes by unmanned aerial vehicle. Trudy MAI, 2020, no 111,

The article considers a method for “suboptimal” routes elaborating for different-type sources monitoring by an unmanned aerial vehicle (UAV). Currently, unmanned aerial vehicles equipped with optical monitoring and radio monitoring tools are used to solve the problem of searching, detecting and coordinates determining of various objects, including radio sources, in remote areas. This is due to the possibility of the direct barraging over the areas of the proposed search objects location. These problems solution requires the UAV optimal movement route, due to the limited resource of its energy carriers. It is quite obvious that the shorter the travel time between optical monitoring areas, the more areas can be surveyed in a limited time. ll in all, it leads to the higher the probability of more searched objects detection and higher the overall monitoring efficiency. However, the majority of scientific and research papers devoted to monitoring systems effectiveness improving with UAVS consider this issue superficially, or not at all. In this regard, the study of UAV flight routes optimization when monitoring sources is quite an urgent task. In the article, the “suboptimal” routes are understood as routes that ensure local extremum in the area of minimizing the UAV movement time between the specified monitoring areas under the impact of dynamically changing air masses movement and with a fixed performance of the UAV power plant. The route geometry impact on the accuracy of determining the radio sources coordinates is shown. Based on the simulation results, these factors impact on the monitoring routes elaboration is estimated. Comparing the results of the flight duration on routes, elaborated according to the developed method, relative to routes elaborated without account for the considered factors, demonstrates a gain in the flight duration reduction by of 5–7% on average, while sustaining the acceptable level of the geometric factor impact on determining the radio sources coordinates.

Petukh N. N., Blagodirev V. A. Circuitry for parrying single and dose effects in satellite receivers. Trudy MAI, 2020, no 111,

This paper introduces new circuitry solutions for protection satellite electronic equipment from space environment which can damage electronic system and crush expensive space mission.

Of particular importance is the ionizing radiation of outer space from various sources both inside and outside our solar system. The functioning of satellite electronic equipment is influenced by several factors include galactic cosmic rays (GCR), trapped protons, trapped electrons, solar energetic particles (SEPs) and Van Allen Belts. The radiation effects of space environment can not only cause degradation, but also disable electronic and electrical systems of the satellite equipment.

To ensure the reliability of the electronic circuits of the on-board equipment, it is necessary to determine the total accumulated (full) dose of radiation «TID» (Total Ionizing Dose), including exposure to charged single particles (single radiation effects (SEE) (Single Event Effects) causing single failures), – forming the radiation medium at a certain height and orbital orientation during the spacecraft flight. Even on high-altitude commercial airliners flying along polar routes, documented cases of avionics malfunctions due to radiation from outer space were recorded.

To reduce the effect TID and SEE, it is proposed to consider circuitry solutions that can prevent premature failures of the satellite electronic equipment exposed to space environment.

Circuitry solutions to parry probable satellite electronic equipment failures (due to the action of heavy charged particles, high-energy space protons and dose exposure) provide a reduction in the effect of breakdown currents on the semiconductor elements of large – scale integration (LSI) and very large – scale integration (VLSI) in satellite equipment.

Tabakov E. V., Zinina A. I., Krasavin E. E. Analysis automation of spacecraft onboard computer cyclograms debugging. Trudy MAI, 2020, no 111,

The onboard computer (OBC) belongs to the basis of the spacecraft control system (CS). It consists of several computational units (faces) duplicating each other. Thus, the spacecraft faultless performance depends upon the OBC operation normativity.

The OBC operation normativity is determined by many criteria. One of the most important of them all is correspondence of the onboard software modules (OSM) operation times to the specified values. The thing is that the CS being considered is the system of the “rigid” real time. The OSM operation times at the OBC faces are being strictly regulated by the cyclogram of its operation. The specified time-frames exceedance may lead to the system failure and spacecraft loss.

Information on the program modules operation completion at the OBC faces are being stored in the telemetric information (TMI) in the form of values the corresponding flags. The TMI contains also a vast volume of other information. Besides, the TMI data representation format is rather inconvenient for human perception. Thus, the approach, at which the operation times analysis is being performed by the TMI files parsing by a human is utterly ineffective, and leads to the great time and labor consuming. Due to this, the task of this analysis automation emerged.

The article suggests the algorithm for this task solving, i.e. automation of this kind of analysis. Based on the suggested algorithm a special software, realizing it, was developed. The development was being performed with C++ employing the QT platform. The application is provided with graphical interface and outputs the results in the form of a table in the separate file. As the result, the developed software simplified significantly such analysis implementation.

Sokhranniy E. P. Data Preprocessing and Priorities Values Computing of Requests on Performing Communication Sessions with Spacecraft of Scientific and Socioeconomic Implication. Trudy MAI, 2020, no 111,

The article covers the final stages of addressing the problem of requests prioritizing for communication sessions performing with scientific and socioeconomic spacecraft, on which the solving methods for main areas of concern on conflicts arising from the engagement of the spacecraft ground control equipment, substantiated in [1], are realized. The initial information for data preprocessing for priority values computing are expert data in the form of Hierarchic Structure (HS) and Relational Matrix (RM), transformed into Comparison Matrices (CM), reflecting the results of qualitative expert estimates scaling into quantitative ones. The order of HS, RM and CM generation is specified in referenced documents [2] and [3].

To validate expert estimates scaling in the form of comparison matrices the last ones are being checked for conformance from the viewpoint of each expert judgments and opinions of the group of experts.

Generalized values computing of HS elements weight factors and requests priorities values for spacecraft communication sessions is performed based on the expert-specified consistent private data on the criticality of factors represented in the form of HS and affecting the conflicts solving procedure.

The developed formal models will allow for complete automation of the request prioritizing process for spacecraft communication sessions, as well as enhance the decision-making promptness and validity of the decisions made to resolve conflict situations.

Guskov A. A., Spirin A. A., Norinskaya I. V. Electromechanical Steering Drive Simulation Model for Small-Sized for Highly Maneuverable Flying Vehicle. Trudy MAI, 2020, no 111,

The task of this work is mathematical and simulation modeling methods implementation at the stage of the design documentation development for electromechanical steering gear to determine its parameters and study characteristics.

Mathematical model of electromechanical steering gear with power stage, consisting of DC motor and reducing gear, representing a wave gear with wave generator was developed. A simulation model based on the electric drive functional diagram and differential equations, describing its operation, was developed in MATLAB Simulink. The study of the steering drive was performed with the developed simulation model. The values of static error of bringing the steering surface to the preset angle, and actuation time and steering speed at various set deflection angles and hinge moment value were obtained.

A prototype of the steering gear was developed and manufactured based on the conducted studies. Electric motor and reduction gear parameters of the steering gear prototype were determined based on the simulation results and refined while designing.

Experimental studies of a prototype steering gear were performed. The time dependences of the steering surface angle of rotation were obtained at various values of the angle being set and without steering surface loading.

Experimental study of the steering drive prototype confirmed its operability.

A comparative analysis of the simulation results and experimental data obtained from the steering gear prototype was performed. It was established that the simulation model reliably reproduces characteristics of the prototype of the object under study.

Thus, the developed mathematical model allows studying the electromechanical steering gear operation and obtain visual results of the system behavior at various conditions and operating modes.

Experimental studies of the created steering gear prototype demonstrated good convergence the simulation results and the experiment, which confirms the adequacy of the developed model.

Application of the developed simulation model while the electromechanical steering development allows saving time and overall cost of product by identifying problems and possible errors at the very beginning of the project, as well as reducing the development effort.

Lyapin A. A. Computational grid compacting for testing computing and control program modules of flight mission built on the input data priority basis. Trudy MAI, 2020, no 111,

The article suggests the mesh-building technique algorithm improving for program modules testing as a part of the software for the flight mission computing and monitoring based on the input data priorities building.

The software support for the flight mission computing and monitoring (hereinafter referred to as SSFMCM) consists of a set of interconnected elements (program modules) [1]. A program module (further PM) is a functionally completed software implementation of a SSFMCM partial task (algorithm). Development and testing of the above said program modules may be realized by the special program tool (BTTesting) application [2-7]. Testing methodology (automated investigation testing [8-15], and calculations automation in aerospace engineering [16]) embedded in BTTesting implies a computational grid formation based on the input data priorities building of the PM being tested.

A testing methodology implemented in BTTesting (automated explorary testing [8-15], automation of analyses in aerospace industry [16]) means the generation of a computational grid on the basis of the attachment of priorities of input data of a PM under test.

The input data priorities building technique and computational grid generation algorithm were presented in [3]. The above appointed algorithm allows increase the number of testing steps for the input parameters with higher priority (the higher the perturbation of the resulting data, the higher its priority). However, the resulting data perturbations depending on the input parameter region variation is unevenly distributed. Knowledge of the above-appointed dependence will allow generation of the computational testing grid with uneven (discrete) step and, thus, increase the number of nodes in the regions with maximum deflection of the resulting data.

The article presents the algorithm for building the above mentioned dependence and discrete computational grid based on the assumption that the highlighted domains (with higher variations of the resulting data) contain maximum number of faults (incorrect decisions).

The developed algorithm allows compressing the testing grid within the input data areas variations leading to maximum deflection of the results, which allows obtaining the greater number of incorrect solutions per the same time unit, and, thus, employ the time resources allocated for testing more effectively.

Tugolukov V. A. Methodological Aspects of Aircraft Carrier Shipboard Aviation Systems External Design. Trudy MAI, 2020, no 111,

The solution searching area formation by the parameters of shipboard aviation systems of the aircraft carrier, and system of preferences and principle of optimality formalization is rather complex optimization problem. Such system of preferences, which the Customer was being governed by, was being completely revealed in the process of analysis and sorting of concretely claimed alternatives of requirements. By formal instructions employing, it was possible to achieve only approaching to those optimality principles, the Customer operated while the system appraisal and decision-making.

In the methodological aspect, the analysis of the shipboard aviation systems is being set by the categorical algorithm of the system research by the “effectiveness–costs–time” common criterion, unfolded in the organizing-system aspect while the aircraft carrier operational functioning as a complex organizing-technical system within the limits of its lifecycle. The basic methodological aspects of the shipboard aviation system of the aircraft carrier external design, invariant to all stages of system optimization are activities focusing, organizational flexibility, multi-functionality, and operational functioning intensity commensuration to the aircraft carrier, i.e. target function.

The requirements for the quality indicators of shipboard aviation systems should be formed in the tactical and technical task to exclude the possibility of their ambiguous interpretation and subjective assessment of the quality of the systems.

The optimization process should be aimed at creating (developing) more efficient and less expensive shipboard aviation systems, and improving functioning quality of the existing systems, avoiding the exhaustive search and evaluation of possible options for shipboard aviation systems and the Aircraft Carrier design.

It is the system-dialectic and organizational-system aspects of external design that represent the basis of the criterion unity (“cohesion”) of optimization, evaluation and adoption of optimal design decisions during the creation, testing and operation of an Aircraft Carrier.

In logical terms, this approach to optimization problems solving summarizes organizational and system optimization regularities, the gist of optimization criteria, and reflects the requests of the design, management and organizational practice of the creation and trials of an Aircraft Carrier.

Kudravtsev A. S., Savchenko N. A., Saveliev I. I. Studying Nonreciprocal Device Based on Permanent Magnet for Zeeman Laser Gyroscope. Trudy MAI, 2020, no 111,

For the first time, the dependence of the frequency non-reciprocity occurring in Zeeman laser gyroscope when the magnetic field of a permanent ring magnet is applied to its active medium was studied with account for the dispersion function nonlinearity of the active medium and non-uniform distribution of the magnetic field along the active medium.

The magnetic field non-uniformity always presents in the non-reciprocal device of Zeeman laser gyroscopes due to the peculiarities of the field distribution of the permanent ring magnet and the monoblock laser design.

The presented work demonstrates the presence of maximum in the dependence of the refractive index on the strength of the magnetic field applied to the medium.

The longitudinal magnetic field non-uniformity of the ring permanent magnet leads to a significant decrease in the amplitude of the frequency bias in the Zeeman laser gyroscope.

The presented work allowed experimentally determine the longitudinal magnetic field non-uniformity.

A technique for evaluation of the frequency bias maximum possible amplitude, which can be obtained in the Zeeman laser gyroscope while its implementation in non-reciprocal device of the ring permanent magnet for the longitudinal magnetic field creating was suggested.

Pogarskaia T. A. Multi-criteria optimization of fasteners placing while aircraft assembling by local exhaustive search. Trudy MAI, 2020, no 111,

The article is devoted to the problem of temporary fasteners arrangement optimizing while aircraft assembly. Fastener number minimization keeping the final product assembly quality is one of the key factors of production intensification in the aerospace industry. The total labor intensity of the airframe assembly process, as well as extensive manual labor employing make the entire manufacturing process of the product multi-stage and time-consuming. Production acceleration requires its intermediate stages optimization.

The article presents three different settings of temporary fasteners arrangement optimization problems, which are studied further at optimization of a certain initial arrangement for the airframe assembly model. A gradientless technique based on local exhaustive search is considered as an optimization technique. Several specifics of the problem under consideration contributed to this technique selection. Firstly, the optimization problem being considered is combinatorial and relates to the NP class. Correspondingly, it is not possible to calculate derivatives, and global optimum can be found by the exhaustive search technique. The local exhaustive search, in its turn, does not require derivatives calculation of the target function. It is based on the idea of the exhaustive search of solutions in the diminished area and consists of independent iterations, as well as allows make modifications into optimization criteria and modify the target function.

Setting of the optimization problems, and the technique, described in the article, are being tested on airframe assembling model. Various multi-criteria optimization problems are being considered and tested, which application is aimed at avoiding the impact of the parameters, being set by the general problem setting, on the result. The article demonstrates that even two different target functions combination ensures more qualitative and stable results.

Protsenko P. A., Skripnikov A. N. . Trudy MAI, 2020, no 111,

One of the tasks that should be solved while the near-moon space development is the task of navigation and ballistic support, which includes the initial conditions clarifying for measuring satellites current navigation parameters.

The rational technology for current navigation parameters measuring seems to be sequential conducting of four to five sessions by one to four means, located evenly on the visible part of one turn of the spacecraft orbiting the Moon. As the result of the conducted current navigation parameters measuring, the achievable accuracy of the initial conditions of the lunar spacecraft is being estimated by measuring current navigation parameters by the selected technology.

In accordance with the technology for performing current navigation parameters measuring, a methodology for accuracy assessing of obtaining initial conditions of the spacecraft position by current navigation parameters measurements has been developed. The methodology is based on obtaining range and radial velocity measurements at the specified intervals of current navigation parameters measuring, and their processing by the least squares method to obtain estimates of the initial conditions of the spacecraft motion. To obtain errors sampling of the spacecraft position while current navigation parameters measurements processing Monte-Carlo method is used, which essence is reduced to multiple modelling of the measured information obtaining process with required mean square deviation values by range and radial velocity measurements at normal distribution law.

Based on the presented methodological approach, a modeling complex was developed that allows evaluate the achievable accuracy of the lunar spacecraft position computing for modern radio means.

The conducted study serves as a guide for predicting the accuracy characteristics of the initial conditions determining for the spacecraft motion in the Moon orbit. Measuring of the current navigation parameters of a spacecraft in the Moon orbit with radio-electronic means from the Earth surface allows estimating the spacecraft location with errors of the order of tens of meters in coordinates and tens of centimeters per second in speed. It is worth noting that the obtained errors of the spacecraft position do not include the errors associated with discrepancies of the mathematical model of motion, used in the least squares method, with the actual aircraft flight process around the Moon.

Bykova T. V., Evdokimova E. V., Mogilevich L. I., Popov V. S. Longitudinal Waves Modelling in a Shell with Physically Quadratic Nonlinearity Filled with Liquid and Enveloped by Elastic MediumLongitudinal Waves Modelling in a Shell with Physically Quadratic Nonlinearity Filled with Liquid and Enveloped by Elastic Medium. Trudy MAI, 2020, no 111,

A perturbation technique for deformation waves simulation based on considering the coupled problem of hydroelasticity in elastic cylinder shell with quadratic physical non-linearity is developing in the presented article. The shell is encompassed by the elastic medium and filled with viscous uncompressing liquid, which inertia of movement is accounted fort while considering its dynamics. The article demonstrates that the presence of encompassing medium leads to integral-differential equation, generalizing Korteweg-de Vries equation, possessing solution in the form of a solitary wave, called solitron. It does not hold an arbitrary constant wave number, in contrast to the Korteweg-de Vries equation solution. The uncompressing liquid behavior inside the shell are being described by the Navier- Stokes equations and continuity equation. They are being solved together with boundary conditions of adhesion to the shell wall. Solution is being presented by direct expansion of the sought functions by the small parameter of the hydroelesticity problem and reduced to liquid dynamics in the framework of the hydrodynamic lubrication theory. As the result, tensions from the liquid side, acting on the shell in longitudinal direction and normally, are being determined. The presence of liquid in the shell adds into the longitudinal waves equation a term, which does not allow finding the exact solution. Thus, numerical study is being realized using up-to-date approach, based on universal algorithm of commutative algebra. As the result of Gröbner differential basis construction, difference schemes of Crank-Nicolson type, obtained using basic integral difference relations, approximating the initial system of equations were generated. Numerical experiment revealed that liquid movement inertia reduced the wave velocity, and liquid viscous friction decreases the wave amplitude.

Zvonarev V. V., Pimenov V. F., Popov A. S. Modelling mutually correlated interferences impact on the signal selection quality in antenna array optimal by mean-square deviation minimum . Trudy MAI, 2020, no 111,

The purpose of the article consists in identifying new qualitative properties based on a computational experiment in Matlab software and clarifying quantitative characteristics of adaptive antenna array (AAA) with the optimality criterion of minimum mean-square deviation in the presence of mutual correlation interference and changing settings of signal-to-noise conditions.

The article considers the properties of the optimal spatial AAA filter as the object of research.

The subject of this article is a quasi-narrowband signal and two interferences at the coinciding frequencies of carrier vibrations acting from different directions.

The relevance of this work is determined by the need to account for the impact of several mutually correlated interferences on the AAA characteristics. Mutual correlation of the two interferences leads to a change in the type of covariance matrix of the received signals and interference at the outputs of the AAA elements. Additional interference component, called correlation interference, occurs at the input and output of the spatial filter unit.

The article presents the results of computational experiment on the study of characteristics of optimal space selectionof a signal and two mutually correlated interferences in the linear equally spaced array, optimal by criterion of minimum of mean square deviation of a signal from reference. New properties of the optimal spatial filter are revealed.

Practical significance of the article lies in the fact that the developed technique allows determine:

– parameters of the signal-noise environment, leading to unacceptable the efficiency decrease of the spatial filter;

– the nature of the signal-to-noise plus interference ratio changing at the output of the optimized antenna array at different correlation coefficient values.

Aminova F. E. Studying guidance and stabilization algorithms effectiveness of “Start-1” space-rocket complex control system. Trudy MAI, 2020, no 111,

The presented study deals with optimization of the testing process of management information system algorithms of complex objects on the example of guidance and stabilization algorithms of the management information system of the «Start» family light carrier rocket onboard complex.

The study practicality consists in application of the approaches for improving the testing processes for guidance algorithms of the space-rocket complex based on international standards not previously employed in the aerospace industry.

The purpose of the study is obtaining the expected end result of the study, assuming the stated contradiction solution by developing a testing model and recommendations for the test tests conducting.

The methodological basis of the study is the theory of systems, system and process analysis.

The following research techniques were employed while this work preparing:

– general scientific techniques such as analysis, synthesis, induction, deduction, analogy, ascent from abstract to concrete and vice versa;

– special techniques such as logical, comparative, and process analysis;

– modelling as well as experimental tecnhiques;

The following software was used as toolbox: BPwin, Erwin Process Modeler (CASE-tools for modeling processes based on the IDEF0 process description standards (functional model)), PTC Mathcad 15 (computer algebra system of a computer-aided design systems class), MATLAB (application software package for technical computing and modelling problems solving)

The study relevance and novelty lies in the fact that international testing standards that not previously implemented in the aerospace industry are being applied for the first time. To this end, analysis of international and Russian standards on software testing and the experimental development of a testing model based on guidance and stabilization algorithms were performed. The results of the study allowed conclude that recommendations on testing are relevant and confirms their practical significance.

Kochetov V. I., Lazarev S. I., Sokolov M. V., Lomakina O. V., Shestakov K. V. Design procedure of geometrical parameters and strength characteristics of roll equipment. Trudy MAI, 2020, no 110,

The article regards the issues of industries, such as aviation and automotive, where products in the form of thin-walled profiles of various cross-sections find more and more application. Basic equipment for obtaining rolled materials, determining the line capacity and the of the products quality, are rolling machines, called calenders, employed in tires, tubes, airbags and hoses manufacturing, operating under high excess pressure. Working organs of these machines represent rolls, rotating towards each other with equal or different circumferential speeds, which axes are located in horizontal plane. The process of materials irregularities transportation is accompanied by dynamic loads, affecting negatively the working organs reliability and products quality. In view of complex kinematics of agitated masses in the effective volume of the two-shafted machines, the existing theoretical methods of the process analysis are limited by the indirect mixing estimation by energy consumption on material deformation in the gap between the rotor and the body wall.

Thus, the purpose of the article consists in developing design procedure of geometrical size and strength characteristics of roll equipment, capable of withstanding the calculated power loads. The design procedure allows minimizing the strength losses arising as the result of fatigue cracks or damages occurrence while the roll equipment operation. Design parameters obtained by this technique allow predicting selection of materials with low rate of fatigue cracks development with determining parts size and application of elements of reliability.

The technique, developed in the presented work, allows obtaining optimal geometric size of the calender roll based on the optimization method application employing a dimensionless complex criterion. The developed technique gives reliable size of the calender roll obtained employing dimensionless complex criterion and methods of target functional optimization without restrictions using penalty functions. The article presents the example of optimal geometrical size selection of roll for the three-roll calendar with penalty functions technique and brute force method, confirming correctness of the approach to the set problem solution.

Dobryshkin A. Y. Oscillations of a rod carrying a small attached mass. Trudy MAI, 2020, no 110,

In this paper, the oscillation of a rod carrying a small attached mass in a nonlinear setting is considered. The basis for the development of a new mathematical model is the general equation of oscillations. The mounting location and the influence of the small attached mass on the frequency characteristics of the natural frequency are taken into account. The first and second eigenfrequency characteristics of the oscillations of the rod carrying the attached mass are determined. It is also determined that the presence of a small attached mass is a factor that triggers the interaction of internal forms of vibration, which can lead the structure to a state of resonance. The obtained values of the wave-forming parameter above zero refer to the solid, and below zero to the weak parameter of the damping force. The presence of several components of the internal oscillatory process is a feature of the system in which the splitting of the frequency spectrum is possible. The small attached mass is one of the inclusions that deviate from the ideal mechanism of harmonic vibrations. The solution of an infinite system of nonlinear algebraic equations uses a new asymptotic approach based on the introduction of an artificial small parameter μ. The case when the system is close to the state of internal resonance is considered. As a result of the study, it was found that the mathematical model specified in the course of the study is better than the existing ones and is consistent with the available data.

Korovaytseva E. A. Systematizing one-dimensional boundary problems of deformed solid mechanics. Trudy MAI, 2020, no 110,

The presented work highlights four ways of problems description of deformed solid mechanics (DSM) existing at present, namely scalar, operator, tensor and vector-matrix. Features of each technique were analyzed from the viewpoint algorithm developing and subsequent programming. The article demonstrates that vector-matrix formalization ensures the most general problem setting, and allows developing most universal and effective solution algorithms. For performing one-dimensional DSM boundary problems systematization the author selected problems solving approach associated with the necessity of employing systems of differential equations.

Sufficiency of considering only one-dimensional problems is stipulated by the fact that multidimensional problems solution algorithms building creates no essential methodical problems compared with the case of one-dimensional problems. Independent of the type, structure, geometry, material, loading or fixing of the structures under study, a unified vector-matrix form is used for the given problem description. The engaged differential equations can be of two types, namely linear and nonlinear ones without any restrictions concerning the range of nonlinearities under study. Three forms are being considered in each type of boundary problem. They are:

  1. the two-point boundary problem,

  2. multipoint unbranched boundary problem,

  3. multipoint branched boundary problem.

As a result, all six forms of boundary problems are assumed canonical. Characteristic feature of the introduced forms canonization is highlighting of the resolving vector of desired variables, being differentiated with respect to a coordinate, as well as vector function of initial values of the problem parameters.

Six more forms of boundary problems with additional algebraic relations were built as well, which are the most widely used when solving applied problems of structures deformation mechanics. These forms can be reduced to linear canonical ones by identity transformations (for linear problems), or to quasi-linear canonical forms when building solution algorithm based on the parameter differentiation method (for nonlinear problems).

Thus the suggested systematization of one-dimensional boundary problems of solids mechanics, based on vector-matrix formalization of the resolving relations, allows reducing the number of problems requiring solution and the number of methods and algorithms of their solution developed, at the same time rising generality of these algorithms.

The irreducible spectrum of one-dimensional problems of mechanics of solids solution algorithms is associated with the six canonical forms introduced in the presented work. When programming algorithms of all the considered boundary problems types solution, only three programs for linear problems solution are basic, corresponding to the first three canonical forms.

Phone H. K., Sysoev E. O., Kuznetsov E. A., Sysoev O. E. Prediction of long-term strength of shaped parts of hydro-gas systems by acoustic emission parameters. Trudy MAI, 2020, no 110,

High-pressure pipelines for hydro-gas systems are widely employed in aviation industry and machine building. Shaped parts of high-pressure pipelines are being manufactured by pressure shaping of structural materials, made of high-strength stainless steels, aluminum and titanium alloys.

Parts shaping leads to various defects occurrence in the structural material, which significantly affects the long-term strength of the products.

Strength calculations under the simultaneous action of internal pressure, tension, and torsion forces on pipelines mainly account for mechanical characteristics of materials, obtained under simple loads, but individual defects obtained while manufacturing the parts of hydro-gas systems are not regarded. Thus, the need in conducting studies and developing techniques that accounting not only for the materials mechanical characteristics under complex stress conditions, but also the evolutionary processes occurring in the material microstructure on the micro level while these structures manufacturing arises.

To account for the micro-processes dynamics and changes in the microstructure of structural materials while the parts manufacturing by pressure processing, the authors proposed to employ the method of acoustic emission (AE).

Acoustic emission occurs in a material under mechanical stress from the release of energy as the result of micro- and macroscopic phenomena caused by local dynamic rearrangement of the internal structure of the material. As the loading force is applied to the structural material, there are displacements of atoms and compaction of material discontinuities at the initial stage. Then the number, condensation and chaos of primary dislocations are increased, leading to dislocation loops and helical dislocations are formed.

As these transformations commencement the emissions of AE signals of corresponding frequency and amplitude occur, which have an individual fractal dimension in accordance with the stage of the microstructure evolution.

Thus, any change in the structure of the material in a complex stress state, as well as the appearance and healing of defects is accompanied by AE radiation. It means that the quantity and energy of AE signals can determine the stage of degradation of the structural material structure.

The article deals with the technique for strength prediction of the shaped parts of pipelines of Hydro-gas systems by the of AE parameters. When the structural material is deformed during the manufacturing process, along with various trajectories in two-dimensional deformation space under a plane stress-strain state, when damage accumulates in the work piece, that affects its strength and durability. Strength determining of the shaped parts of hydro-gas systems depends on mechanical characteristics of structural materials, methods of deformation and becomes a difficult task, since the defects accumulated by each part are individual. The article demonstrates the process of microstructure changing of aluminum alloys in the process of deformation. The durability prediction of parts fabricated by the process of metal forming was studied. A stable dependence for determining the time to failure for D16 alloy by the AE parameters with a fractal dimension of the of acoustic signals 1 ≤ D2attr ≤ 6 from the effect of internal pressure stresses in the manufacture of parts by process of metal forming was obtained.

The technique proposed in the article allows not only pridicting the long-term strength of shaped parts of pipes of hydro-gas system but also determining the time to failure for these parts by the AE parameters with a fractal dimension of the attractor of acoustic signals 1 ≤ D2attr ≤ 6.

Golovan V. I., Dudarkov Y. I., Levchenko E. A., Limonin M. V. Load bearing capacity of composite panels with in-service damages. Trudy MAI, 2020, no 110,

The article presents the results of numerical and experimental studies of residual strength of composite panels with in-service damages. The issues of damage size impact on buckling and strength properties of panels, as well as on their modes of failure while the critical state achieving, were under study. Structural panels of wing and empennage of the airframe structure of a long-distance aircraft were considered in conditions of uniaxial compression. The article presents experimental data obtained while compressing tests of panels with normalized impact damages, and gives its comparison with computational results. Virtual modelling of experiments was performed based on finite element method including the geometrically non-linear problem setting, realized in NSC Nastran and Marc software complexes. A technique for numerical studies performing and methods for damaged area modelling are described. It is demonstrated that modern numerical methods allow predict the load-bearing capacity of structural composite materials in both initial state and in the presence of defects in them. The difference in reaction of highly-loaded wing panels and medium-loaded empennage on in-service damages was established by the parametric studies results. Destruction mode associated with the process progressive growth of the damage zone is characteristic for the panels of the first type. The load bearing capacity for the panels of the second type is determined in a greater degree by the total or local buckling. It was shown also that the damage effect on the residual strength of the composite panels depended on the energy of the impact to which all structures might be subjected while their operation, as well as on the place of the damage location. The technique for computing-parametric studies performing proposed in the article can be employed for preliminary estimation of normalized in-service damages impact on the load bearing capacity of panels from CFRP, and required level of allowable stresses to meet the strength safety requirements of composite structures. The obtained results can be useful at the draft design stages to formulate appropriate destruction criteria.

Bykova T. V., Mogilevich L. I., Popov V. S., Popova A. A., Chernenko A. V. Radial and Flexural Vibrations of the Round Three-Layered Plate Interacting with Pulsating Layer of a Viscous Liquid. Trudy MAI, 2020, no 110,

The presented work formulated and solved the problem of forced radial and flexural hydro-elastic vibrations of the round three-layer plate. The study of a plate with light incompressible filler under the action of normal and shear stresses from the side of the pulsating layer of the viscous incompressible liquid was performed. The axisymmetric problem, in which the plate was regarded as the lower wall of the narrow channel, filled with a viscous fluid, was studied. The fluid movement in the channel was considered as a creeping one. Equations of the three-layer plate dynamics were obtained based on the zigzag normal hypothesis and the D’Alembert principle. The developed mathematical model consists of dynamic equations of a viscous incompressible fluid layer and dynamic equations of the round three-layered plate. The following boundary conditions were selected:

– liquid sticking conditions to the channel walls;

– the liquid free-flow conditions at the channel end;

– the plate rigid fixing conditions;

– and conditions of limited liquid pressure and the deflection plate at the symmetry axis.

The hydrodynamic parameters distribution of the fluid layer as the plate deflection functions was found, and resolving equations for determining the plate elastic displacements were obtained. The amplitude-frequency responses of the radial and flexural plate displacements corresponding to the main mode for the steady-state harmonic oscillations were plotted. The numerical study of the radial and flexural oscillations amplitudes on the main mode, which demonstrated the mutual effect of the inertia and stiffness forces of the three-layered plate in the radial and normal directions, was performed. The performed computation revealed a significant impact of inertia forces in the normal direction on the amplitude-frequency response of the plate radial displacements. On the other hand, the computations showed a slight effect of inertial forces in the radial direction on the amplitude-frequency response of the plate deflections.

Sapozhnikov V. B., Koroljkov A. V., Konstantinov S. B., Alexandrov L. G. Experimental estimation of unusable fuel of upper stages at the flight final phases. Trudy MAI, 2020, no 110,

The article deals with the physical modelling of the spacecraft upper stages’ tanks emptying from the fuel components in condition of acceleration of various values impact on the liquid. The Froude number was selected as modelling criterion. The research experiments are conducted on the transparent physical model of the tank, being filled with various quantity of the model liquid, which flows out from the model with various consumption values while the research container with the model drop in the “weightlessness shaft” (or “drop tower”).

The tests determine the Froude number impact on the unusable liquid remnants in the model, caused by the “dynamic drop” of the “liquid-gas” interface surface into the drain port of the tank while its depletion (“funnel forming”). Approximation formula of the dependence of the unused remnant volume on the Froude number while tank depletion was obtained. It was demonstrated by the results of the experiment that the obtained dependence describes rather accurately the process under study up the Froude number of Fr ≤ 104. Within the range of Froude numbers values of Fr > 104, surface tension forces start to affect the result, and besides the Froude number, the Bond number should be accounted for while physical modelling.

Berezko M. E., Nikitchenko Y. A. Comparison of combined kinetic-hydrodynamic models of different orders on the example of the Couette flow. Trudy MAI, 2020, no 110,

Boundary conditions formulating on a solid surface for moment equations systems represents significant complexities.

A strict formulation of such boundary conditions was obtained only for the Navier-Stokes-Fourier model (NSF) being an incomplete system of second-order moment equations. Under high non-equilibrium conditions, the NSF model with its corresponding boundary conditions significantly overestimates the coefficient of friction on the streamlined surface. Previously, the authors proposed a combined flow model supplementing the NSF model in the near-wall region with a kinetic equation with appropriate boundary conditions. This combination of hydrodynamic and kinetic models allowed significantly improving the solution in the near-wall region.

The presented article proposes a combined physical and mathematical flow model, employing model kinetic equation for polyatomic gases within the Knudsen layer, and the third-order system of moment equations (M3) within the rest of the computational domain. In the region of models concatenation approximating distribution function, representing a decomposition of the Maxwell equilibrium distribution function by the thermal velocity degrees, is being restored. Parameters of decomposition (non-equilibrium stresses and third-order moments) are determined in the M3 model approximation.

The example of the test problem solving for Couette flow demonstrates that this option of the combined model yields smooth solutions in the field of models’ concatination and allows a satisfactory accuracy of the flow field description in a wide range of Knudsen and Mach numbers. Both options of the combined model were compared. Analysis of the results revealed M3 hydrodynamic component employing in the combined model allowed enhancing the acceptable range of Knudsen numbers approximately by an order, while the Mach numbers could be increased up to hypersonic values.

Vuong V. T., Gorelov S. L., Rusakov S. V. Effects of non-monotony of aerodynamic characteristics of a plate in hypersonic rarefied gas flow. Trudy MAI, 2020, no 110,

The study of rarefied gas flows allows revealing a number of effects that are not observed in the continuous flows. Despite the fact that the studies in this field are being conducted for more than 50 years, some properties of such flows are far from being well studied. For example, effects of non-monotony of aerodynamic characteristics for a plate in the hypersonic rarefied gas flow by Reynolds numbers have been previously studied in the works [1, 2]. However, behavior of these characteristics depending on different angels of attack has not been studied up to now. Thorough studies of these effects by the direct simulation Monte Carlo (DSMС) technique depending on the key parameters such as Reynolds numbers, angle of attack, temperature factors and temperatures ratio of the plate surfaces were conducted in the presented work. It was revealed that with equal temperatures of the plate sides, the friction coefficients remained non-monotonous up to the angle of attack of 10 degrees, and up to 30 degrees by the pressure coefficient. Based on the obtained calculations, approximate analytical dependences of the coefficients of friction, pressure and lifting force on the angles of attack and temperature factors in a wide range of Reynolds numbers are proposed. These dependencies were applied for aerodynamic characteristics determining for arbitrary shape bodies in the framework of the local interaction hypothesis, and performed comparison demonstrated good conformance with the other authors’ data and experiment. At small angles of attack and different temperatures of the plate sides the lift coefficient changes its sign depending on the Reynolds numbers, and there are values of the angle of attack an temperatures ratio on the plates surfaces, at which the lift coefficient equals to zero.

Doan Q. H., Firsanov V. V. Edge stress state of variable thickness rectangular plate based on refined theory. Trudy MAI, 2020, no 110,

Recently, a growing interest in developing refined theories of plates and shells is observed. This interest is aroused by the necessity of studying stressed-deformed state (SDS) while developing elements of modern structures, including aerospace engineering products. The article considers the edge stress state of isotropic rectangular plate of variable thickness under action of local load based on the refined theory. A mathematical model of additional stress state of “boundary layer” type, occurring near the clamped edge of the plate was developed. Three-dimensional equations of elasticity theory are applied while this mathematical model development. The displacements are approximated by the polynomials by the coordinate normal to the median plane two powers higher relative to the classical theory of Kirchhoff-Love type.

A system of basic equations of the refined theory and corresponding boundary conditions were obtained by the variation Lagrange principle. The solution of the formulated boundary value problem is accomplished the trigonometric Fourier series methods, finite differences, and matrix sweeps. One of distinguishing features of the proposed refined theory consists in the fact that direct integration of the equilibrium equations of the three-dimensional elasticity theory is employed while transversal and normal tangential stresses determining.

A refined mathematical SDS model of the rectangular plate with variable thickness, symmetric relative to the median plane in the longitudinal direction, was developed in this work. The article presents a comparison of the results obtained by the refined theory with the classical theory data. This technique allows consider not only the thin plates but also the plates of medium thickness. It was established that this refined theory should be used when studying the stress state in the zones of its distortion (joints, local loading zones, etc.). Additional, in relation to the classical theory, transverse normal stresses, are appeared to be of the same order with maximum values of the main bending stress. This result is important as it allows obtain more reliable evaluation of the strength and crack resistance of aircraft structural elements, as well as other machine building objects at the design stages.

Pushchin R. V., Pykhalov A. A. Stress analysis of the locking part of aircraft engine rotor blades with finite-element solution of contact problem of elasticity theory. Trudy MAI, 2020, no 110,

The article regards the stress-strain state (SSS) analysis of the compressor rotor blades attachment of aviation gas turbine engines (GTE). The study is based on the finite element method (FEM) and the contact problem solution of the elasticity theory. As an example, the rotor blades structure with its attachment in the disk with a trapezoidal lock (Dovetail type) under the impact of a centrifugal load is considered. Parts designs are modeled by finite elements of the volumetric stress-strain state. The contact mating between the lock and the disk is modeled employing a special contact finite element. The results presented in this work demonstrate a complex picture of changes in mating conditions on the lock working surfaces. The results of calculations are shown in comparison with the results of traditional calculations. The difference manifests itself in the form of refining the value of places of stress concentration under the impact of various structural and technological factors of the blade attachment with a trapezoidal lock Thus, the calculation approach presented in the article allows detect the regularities of specifics of the impact of blade attachment elements on the product efficiency.

The purpose of the study consists in analyzing the features of three-dimensional parts models of the lock joint and changes in the conditions of their mating in operation. The proposed article presents the possibilities of the finite element method implementation (FEM) based on the solution of the contact problem of the elasticity theory.

The authors concluded that the static model was a preparatory stage for developing a new dynamic model of an aircraft engine.

Shipko V. V. Noise-resistant complexing of multi-and hyperspectral images in optoelectronic information support systems for modern and prospective helicopters. Trudy MAI, 2020, no 110,

Currently, multi-channel Earth surface monitoring systems both air- and space based are being intensively developed. Helicopter information support systems (pilot survey, search survey, and sighting), which include multispectral and, in the future, hyperspectral optical radiation sensors that will be integrated into a single information system, are of no exception. Application of hyperspectral photography allows increase the detection and recognition efficiency of scene objects. In turn, while hyperspectral photography, the detected radiation is being split into hundreds of components of the generated hyperspectral image, which leads to a significant decrease in the level of the useful signal in relation to noise. Hyperspectral images are subjected to additive uncorrelated noise, which can reach high levels. At the same time, there are quite strict requirements for high spatial resolution of such complexes.

There are many image processing techniques and technologies, and one of the most important areas of processing multi- and hyperspectral images is their complexing.

The article considers an algorithm for multispectral images complexing in conditions of additive Gaussian noise, based on the interchannel gradient reconstruction technique. The proposed algorithm allows eliminate highly dispersed values of noise amplitudes in the multispectral image spectral components while their complexing. It also allows increasing the local contrast of the resulting image, containing elements of the original images of the same scene, obtained in different spectral ranges, while preserving the contour features of objects from all the spectral components of the multispectral image and the brightness portrait of the priority spectral component. The article presents examples of complex images and results of numerical studies, confirming the effectiveness of the proposed method are presented.

Mehtiev R. F., Savelyev A. N., Solod A. G. Hardware and software complex of operational monitoring tools for radar side remirroring of anechoic shielded chamber. Trudy MAI, 2020, no 110,

The subject of study is the operational evaluation technique of the anechoic ratio of an anechoic shielded chamber (ASC) for conditions realization of radio wave propagation in free space while studying antenna and microwave devices of radio electronic systems and complexes as a part of hardware and software complex of operational monitoring tools for radar remirroring.

ASC application allows sharply reduce or completely eliminate full-scale test, which leads to significant cost and time saving. They are employed at every stage of radio-electronic equipment developing. The main characteristics on electromagnetic compatibility (EMC) at the specified size, operating frequency range and polarization are:

– normalized Site Attenuation (NSA);

– field irregularity in the work zone (AIWZ);

– voltage standing wave ratio (VSWR);

– anechoic ratio (AR).

The above listed indicators of ASC quality characterize its «isolating» properties, as well as also the properties, guarantying unambiguity and accuracy of the performed measurements.

The required AR full-scale insuring is a complex scientific and technical task. In most practical cases AR is not ensured in the entire ASC volume, but only in its part. Difficulties of the work zone forming in the ASC space are determined by its uniqueness for each concrete study (test). On the one hand, the uniqueness depends on the ASC shape and size, the type of radar absorbing material and its placement. On the other hand, it depends upon the radiation zone determined by antennas location options, radiation sources and auxiliary tools (antenna supports and their dynamic complexes). Thus, besides attestation, including periodical one, it is necessary to be in a position to ascertain in ensuring the required minimum reflection level in the work zone of the required size.

Therefore, it is necessary to be able to quickly verify the required minimum level of reflection in the operating area of the specified size during practical measurements in spite of periodic certifications.

Employing the hardware and software complex of operational monitoring tools for radar side remirroring 2–3 times accelerated calibration process in the work zone, and allowed successfully conduct State testing of satellite signals of three types of prospective products, namely aircraft, helicopters and unmanned aerial vehicles.

Britvin N. V., Meshavkin K. V. Queue management algorithms analysis for information interaction improvement by network encoding technique. Trudy MAI, 2020, no 110,

Rapid development of mobile devices and increase in their production leads to a transport collapse in telecommunication networks. The form factor reducing of such devices sets a new trend in their production, aimed at wireless access to the global network. Due to this fact, a problem with the frequency range is already observed, which, in its turn negatively affects the information interaction [1, 2, 3].

Besides the above-described problem, the TCP/IP protocol stack, just like most standards and algorithms for transmission and generation of packets, was aimed at the wired segment, which, in turn, is free from some disadvantages of the wireless segment [4].

Most MANET devices employ the Tail drop queue management algorithm [11], in which packets are received until the queue is full and starts discarding them. If the buffer is constantly full, the network will be overloaded. Retransmission of the discarded packets requires additional resources (mobile device battery consumption and the channel throughput). In the case of multiple short TCP sessions on the network, congestion ensues, and the so-called “Global TCP synchronization” may occur. Based on points stated above, we can conclude that the Tail Drop uses the router memory irrationally.

The RED algorithm starts to discard packets when the queue starts filling up. When the queue size exceeds a certain maximum threshold, the probability of discarding a packet becomes equal to one. Thus, all incoming packets are discarded. The RED algorithm is effective enough for its selection in most queue-based devices, along with its modifications, such as WRED and CBWRED.

Valaitite A. A. Estimation accuracy analysis of zenith tropospheric delays obtained by precise point positioning technique. Trudy MAI, 2020, no 110,

At present, the number of application domains of global navigation satellite system (GNSS) receivers increased. Besides the tasks requiring high precision positioning such as geodesy, navigation, autonomous control of equipment, navigation data is used to such atmospheric parameters monitoring as integral water vapor content, pressure, tropopause height. Another example of the GNSS employing receiver, beyond the tasks associated with the consumer positioning, is track delay integration, obtained from the receiver with microwave radiometer measurements with the view of high-precision estimation of the tropospheric delay wet component for altimetry products

An accurate calculation of the values of zenith tropospheric delays can be obtained by the Precise Point Positioning (PPP) technique. PPP technique is a secondary measurement processing method allowing achieve centimeter positioning accuracy with a single GNSS receiver. The values of zenith tropospheric delays (ZTD) herewith will be estimated directly in the Kalman filter with the rest unknown values such as position, clock offsetting and velocity.

Due to the growing interest in this positioning technique, associated mainly with the possibility of its application in various fields, many ready-made algorithms for its implementation exist, both as online services and as software packages.

This article presents a comparative analysis of estimates accuracy of zenith tropospheric delays obtained by navigation measurements processing from the four ground-base stations of the International IGS network with three software products, namely gLAB, CSRS-PPP and MagicGNSS.

Zenith tropospheric delays estimated by this means were compared with reference tropospheric delays in the “*.zpd” format, provided by the International GNSS service.

The presented study revealed two basic tendencies. Firstly, it was found that MagicGNSS and CSRS-PPP software products allowed obtaining ZTD estimates rather close to the IGS tropospheric product value. Secondly, the dependence between the time of year and zenith tropospheric determining delay accuracy was revealed.

Solomatin M. S., Mitrofanov D. V. Intelligent detector model of automated control system protection system. Trudy MAI, 2020, no 110,

At present, information technologies development, the emergence of new threats to the information security of information systems, such as any automated process control systems, as well as with increasing requirements for data security, led to the need of creating or constantly upgrading the existing information protection systems

Threats to the integrity, accessibility and confidentiality of information to the stored and processed data in automated control systems (ACS) can lead to loss of prestige of the organization, financial problems, threats to state and corporate secrets protection, etc.

Traditional methods of attacks detecting do not allow achieving optimal characteristics of internal attacks detection. The analysis reveals that attack detection systems building based on artificial immune system technologies is quite promising. This technique has several advantages over other methods, ensuring:

– high speed;

– a relatively simple learning algorithm;

– low resource consumption.

As a consequence of artificial immune systems, a promising area of research in the field of information protection of automated systems is the “intelligent detector” tools development. For further software realization and implementation in automated control systems, it is necessary to describe the requirements that will be imposed on the intelligent detector, basic functions of operation, and basic elements of the intelligent detector.

By the “intelligent detector” we will mean a system, operating in real time mode, protects against unauthorized access by automatically detecting external/internal impacts or threats, and elaborates an appropriate solution to eliminate or slow them down.

The requirements for the intelligent detector system include:

1. The objectivity (reliability) of the result. Evidence that vulnerabilities do exist in the information system, and describe in detail the possible consequences of their implementation.

2. Completeness of the description of possible vulnerabilities in the system.

3. General recognition of security assessment criteria. Employing simple and clear criteria for assessing information system sequrity.

The functions of an intelligent detector system can be divided into external (identifying and suppressing attacks) and internal (identifying and eliminating vulnerabilities).

The functions of an intelligent detector system can be splitted into external (identifying and suppressing attacks) and internal (identifying and eliminating vulnerabilities).

The intelligent detector of an information system, in our opinion, should perform the following functions:

1. Perform information gathering from the system.

2. Process the received information for a further solution developing.

3. Identify the cases of security policy breach.

4. Develop appropriate system responses to violations.

Barkova M. E. Technogenic space debris reprocessing into fuel on low orbits. Trudy MAI, 2020, no 110,

The main problem of article is spacecraft project creation for space debris utilinzation.

The purpose of the presented work consists in concept developing and designing an CSD spacecraft, which will allow space debris reprocessing into a fuel.

This work urgency consists in near-earth space clearing from space debris by its reprocessing into a fuel.

Basic shortcoming of the existing projects of technical devices is crushing of bulky space debris that leads to smaller fragments formation.

The article suggests employing the concept of pseudo-liquid fuel creation. Pseudo-liquid fuel is a fuel from the fine metallized powder in a gas media. The CSD spacecraft f purpose consists of a space debris catcher and a system for its utilization by reprocessing into a pseudo-liquid fuel.

The obtained results can be applied while CSD spacecraft design and operation.

The author concludes that space debris reprocessing into pseudo-liquid fuel is most expedient as this type of utilization of space debris is waste-free.

The author’s undoubted merit of is creation of the invention named “A spacecraft for space debris utilization”, as well as the CSD operation developing.

The prospect of further developments in this field consists in the space debris reprocessing system improving to reduce economic spending for the project, further development of the CSD shock-proof frame and its fan-shaped solar collector to avoid breakages while the space debris gathering, as well as the CSD project improving for subsequent implementation.

Pogarskaia T. A. Fixture elements arrangement optimization when aircraft assembly based on mesh adaptive direct search. Trudy MAI, 2020, no 110,

The presented article is devoted to the problem of the arrangement optimization of fixture elements while aircraft assembly. Minimization of fixture elements number preserving the final product quality is one of the key factors of production intensification in aerospace industry. The objective of the work consists in verifying further application possibility of Mesh Adaptive Direct Search and its modification to the problem under consideration. This method is stipulated by its following specifics, such as no need for derivations computing, and the structure, which implies two independent computing blocks. The first feature is important since the optimization problem under consideration is combinatorial and relates to the NP class. Correspondingly, derivations computing is not possible, and the global minimum can be found by the full enumeration method. The second feature, namely steps independence, opens the possibility of employing any algorithm as a search step. The article considers the following approaches: black box optimization, black box optimization with spatial relaxation of forces and a technique of modified step of searching based on total information on the problem being solved.

Computations were performed on the test model of the wing attachment with fuselage. The results are compared with Local Variation Method (a greedy algorithm) to evaluate their efficiency and possibility of their further application for optimization of full-scale models. Mesh Adaptive Direct Search proved to be applicable as it allowed obtain improved relative to the initial fixture elements arrangement. Modification of the algorithm searching step based on total known information ensured the best balance between computation time and the final result quality.

Belyakov A. Y. Solid fuel combustion surface modelling with regard for heat-conducting elements. Trudy MAI, 2020, no 110,

The presented article describes a program for a charge of solid or paste-like rocket fuel combustion surface modelling, developed in MATLAB package. Initial data for the charge combustion surface forming includes heat conductivity factors of all fuel charge elements (of the fuel itself and all thermal conductive elements it contains), the charge geometry, stored in the form of a table (finite elements mesh), and the fuel combustion law. The fuel combustion law accounts only for the charge temperature field without considering combustion products pressure in the chamber and erosion processes, since it is quite sufficient to obtain qualitative pattern of the process being considered. The charge temperature field at each time instant is formed by solving the equation of thermal conductivity in finite differences. The article presents derivation of the equation of thermal conductivity fr om the differential equation of thermal conductivity. The results of the program execution are presented in the form of a table wh ere zones of solid, gaseous and transient states of the fuel are highlighted by various colors. Qualitative comparison of the obtained results (the charge combustion surface at a given time instant after the burning commence) with the results of the experiments on the subject of interest was performed. The trend for future works in the field was proposed as well, namely, on programs creation for designing rocket engines, operating on solid- and paste-like state fuels, with thermal conductive elements included into the fuel charge.

Gusev P. Y., Gusev K. Y. Prediction of production plan implementation of aviation enterprise employing a fuzzy neural network. Trudy MAI, 2020, no 110,

Prior to a new product production startup or changing production program of aviation enterprise, it is necessary to unambiguously determine whether there are enough production resources to fulfill the new production program. The answer to this question is possible only in the case the presence of sufficient amount of reliable information on the production work.

In cases where information is insufficient, the authors propose to use simulation model as an information source. The article considers a simulation model of a workshop for parts production fr om polymer composite materials. The developed model was verified by the key points of production. In the simulation model, a series of experiments was carried out where production plan was the variable parameter, and the fact of the monthly production plan fulfillment was the criterion.

Based on the experiments, a data set was generated. This data set was analyzed, and certain conclusions were drawn on the production work.

To automate the predicting process, a fuzzy system model with an external knowledge base is employed, wh ere the Gauss function is used as a form for representing fuzzy sets. The first stage of this model functioning is a knowledge base compilation from the training sample in the form of “input vector”-“predicted value” pairs. The data in the knowledge base is stored in the form of membership functions for the corresponding Gaussian curves rather than in absolute values. At the second stage, using the generated knowledge base, a forecast is performed by calculating the degree of belonging of the existing situation and the reference.

The fuzzy-neural network functioning with fuzzy sets is required to perform mathematical operations performed by the following blocks: a block for bringing state variables to fuzzy sets, a block for generating a solution, a block for mapping output fuzzy sets to the forecast value.

Based on the above-described algorithm, a software module for the production plan analysis and its fulfillment forecasting was realized. The developed module allows employing various data entry formats, as well as conducting experiments.

A test sample was analyzed, from which a knowledge base was being formed, and control checks on the test sample were carried out. The results of check test gave 93% of forecast matches in the test sample.

Blinkova O. V., Kondratov D. V. Interaction Dynamics Problem of a Layer, Being Squeezed, of Viscous Compressible Gas with Elastic Plate. Trudy MAI, 2020, no 110,

The rapid process of technology and engineering development in the modern world leads to the necessity of developing and considering mathematical models of thin-walled elastic structural elements. The study of elastic thin-walled structures, the space between which is filled with a viscous liquid or gas, is becoming increasingly interesting. The article tackles the problem of modeling the flow of a viscous compressible gas in a slotted channel consisted of two plates. The first plate is rigid, and performs harmonic vibrations in the vertical plane (vibrator), while the second one is represents an elastic plate (stator). Mathematical model in dimensionless variables is a coupled system of partial differential equations, describing motion dynamics of a viscous compressible gas (Navier-Stokes and continuity equations) flowing between two plates and an elastic beam-strip with the corresponding boundary conditions. To solve the set problem of a viscous incompressible gas and an elastic linear plate interaction, we switched to the dimensionless variables of the problem. Small parameters of the problem, i.e. relative width of the viscous gas layer and relative deflection of the elastic stator, were selected. These small parameters of the problem allowed using the perturbation method to simplify the system of equations. The article presents a technique for solving this problem, being a combination of the direct method for solving differential equations and the Bubnov-Galerkin method. An expression for the amplitude-frequency response of the elastic stator was obtained. The study of the amplitude-frequency response of the elastic stator will determine the operating modes under which the resonant phenomena occurs, and accounts for them when developing new structures in the modern engineering and aerospace industries. The presented mathematical model can find application in gas-dynamic vibration mounts and dampers.

Sizov D. V., Aslanov V. S. Space debris capturing technique ensuring its safe tether-assisted towing. Trudy MAI, 2019, no 109,

Rockets upper stages are one of the most dangerous type of space debris, not so much herewith due to their weight and size, making collision with them rather dangerous, as they might spontaneously explode due the presence of residual fuel, creating plenty of debris with unpredictable trajectories. In this regard, many ways of space debris removing, and spent rocket stages in particular, have been proposed and analyzed in recent years. One of such methods is tether-assisted towing of passive space debris (object) by an active spacecraft (tug) to the upper atmosphere. The article considers the process of removal, consisting of three stages: harpoon capturing of the object, tether unwinding, and towing. Towing will be safe if both the tether and the object are oscillating around their equilibrium states. In this regard, the authors propose a capture technique, which employs the impact impulse from the harpoon to reduce the initial angular velocity of the object so that it will move to the position required for safe towing while the tether unwinding. Dependencies allowing determine the required position of the harpoon point of impact, and the object orientation at the moment of capture are presented. A tug thrust control law while tether unwinding, ensuring the tug reaching the specified point with the specified speed, is proposed as well. As an example of the proposed approach application, numerical modelling of the Ariane 4 rocket upper stage removal is presented. The numerical modelling results revealed that with the specified tug thrust, the tug’s reaching the specified position with subsequent towing was possible in the wide range of the tug masses. The results of the presented work can be employed for planning future missions on space debris removal from low near-Earth orbits.

Nizametdinov F. R., Sorokin F. D., Ivannikov V. V. Developing a shell finite element for large displacements of aircraft structural elements modelling. Trudy MAI, 2019, no 109,

Structural elements in mechanical engineering, including structural aircraft elements, are often described by a model, for which large generalized displacements at small deformations are characteristic. Thus, the parts, such as aircraft skins sections or aircraft engine housings, while considering evolution; thin-walled rotors etc. can be referred to these elements [1, 2].

Application of a moving coordinate system associated with an aircraft leads to the necessity of introducing extra inertial loads (gyroscopic, Coriolis, et-cetera) while an aircraft evolution considering. In case of deformable systems, such as aircraft hull and wings, it leads serious complications in mathematical description of a finite element. However, if immovable coordinate system, associated with the Earth, is employed, then the necessity for the extra loads does not arise, since the movement is not decomposed into translational and relative components, though large rotations, which an aircraft performs while moving relative to the Earth, should be herewith accounted for.

The purpose of the article consists in developing such a finite element, in which displacements and rotations are large, while deformations and, hence, relative changes of the element size are small.

Many works were devoted, and a whole number of techniques were developed to solve the problem of describing large displacements of structural elements to determine displacements and power factors in them. A rather complete review of these works and techniques is presented in [3, 4]. Particularly, works [3, 4] mentioned the corotational approach with the Euler vector application for finite rotations description, which was employed in this paper. This approach is rather new. Thus, it has not yet reached the same level of popularity as the Lagrange approaches both general and modified [6, 7].

Despite its novelty, the approach is based on the old idea of separating displacement as rigid whole and purely deformational motions. Each approach has its drawbacks. Lagrange approaches have one common disadvantage, which consists in the fact that each element must be recoded from scratch for geometrically nonlinear analysis [8]. The main drawback of the corotation approach is the problem of tracking the shadow position, and selecting the point with which this position is associated. However, there are studies demonstrating that the best choice is binding to the element center of mass [9].

Due to the growing interest in such an approach, many studies devoted to the development of ordinary [10, 11] and specialized [12-15] finite elements using this method appeared in recent years. The main differences of the approaches proposed in this paper are the possibility of obtaining fully analytical relations for the stiffness matrix and the vector of elastic forces; the ability to describe unlimited large rotations, and the absence of the need to additional degrees of freedom introducing.

The Euler vector used in this work is the most common and natural way to describe finite rotations [16-19], though, the Euler vector has a disadvantage, consisting in the presence of a limit value of the rotation angle (2π). With this rotation angle value, the tensors linking small physical rotations with derivatives of kinematic parameters appear degenerate. To overcome the problem, the presented work employs modification based on Euler vector correction while approaching the limiting value. The modification is described in detail in [3] and is not linked to both the base element or to the number of nodes.

The article presents an algorithm for deriving the tangent stiffness matrix and the vector of elastic forces for a geometrically nonlinear shell finite element on the example of a four-node finite element. However, the algorithms are of rather general character and can be applied to almost any basic element (not necessarily a shell) without significant changes.

Based on the test problems solution results, an inference can be drawn on the derived relationships correctness, rather good accuracy of the developed element, which allows its successful application for computing structural elements of machines, subjected to large generalized displacements at small deformations. Besides, the authors can claim that the developed element possess high performance compared to the analogs due to the transparent closed analytical expressions for tangent stiffness matrices and the nodal force vector.

Voropay A. V., Grishakin V. T. Viscous friction modelling in material of a plate under its non-stationary loading with differential and integral operators. Trudy MAI, 2019, no 109,

The article presents results comparison of deflections computing in a certain point of a viscoelastic plate, obtained within the framework of classical Kirchhoff thin plates theory with the results of the similar computing based on the refined theory of Timoshenko type for medium thickness plates. Transversal pulse loading of a rectangular homogeneous isotropic viscoelastic plate, hinged along its contour, is considered while computations. Accounting for internal viscous friction based on Kelvin-Voigt model for Kirchhoff plates was realized by the well-known approach, employing differential operators.

The article proposes a new approach to transient analysis in a viscoelastic continuum caused by non-stationary force disturbances, based on integral transformations and the Efros theorem. This approach employs a smoothing linear integral operator and can be applied to any solutions, obtained in the framework of elasticity theory, which can be represented in the form of Duhamel’s integrals. The possibility of relatively fast recalculation of the plate deflections and deformations with account for the internal friction for various values dissipation and vibration coefficients is not excluded herewith.

The presented graphs allow making a conclusion that integral and differential operators application to account for energy dissipation while viscoelastic plates deforming (moreover, with various hypotheses of deformation by Kirchhoff and Timoshenko) gives close results. That is, the solutions, obtained by the two independent methods for different differential equations, practically coincide. This fact confirms the new developed approach propriety, correctness of smoothing integral operator application and veracity of performed calculations.

The indisputable advantage of the approach presented in the article, which employs smoothing linear integral operators for solving the deformed solid mechanics problems, as applied to viscoelastic continuum, consists in the fact that it does not utilize information on frequencies and shapes of free vibrations of the object under study. Thus, the suggested technique is not sensitive to the boundary conditions description errors and imperfection of the accepted hypotheses of deformation (Kirchhoff, Timoshenko, etc.). Due to the above-said property, the suggested approach can be effectively employed while data processing of full-scale experiments.

Dobryshkin A. Y., Sysoev O. E., Sysoev E. O. Experimental verification of mathematical model of forced oscillations of an open thin-walled shell with a small attached mass and rigidly clamped edges. Trudy MAI, 2019, no 109,

The article regards the problem of numerical characteristics determining of a rectangular in-plan view open thin-walled shell, rigidly pinched along one of its sides.

A theoretical analysis of theories of oscillations of an open cylindrical shell and a curved plate was performed. The shell calculation was performed based on the Germain-Lagrange equation using asymptotic methods for solving differential equations, the Padé approximation, and the recursive perturbation theory. Approximation was performed by expansion in a series in a variable of wave-forming parameter. Analytical dependencies were obtained between the shell oscillation frequency and the wave-forming parameter of a cylindrical open shell. The performed studies were verified by the experimental studies. For these purposes, a special test facility was developed, test samples were fabricated, and a program of experimental studies was developed. Mathematical models and the shell vibrations studies refinement is necessary to reduce the onset of resonance effects and prevent accidents. The numerical data determined with the Padé approximation is very accurate, and describes perfectly frequency characteristics of the oscillatory process at the wave-forming parameter staying within the range from zero to unity. The data obtained in the course of the experiment setting up, represents minimal discrepancies for the RTV method (recursive formulation of perturbation theory). In the range of the wave-forming parameter less than 0.5, the data obtained during the experiment setting up, are inconsistent with numerical data determined using the Padé approximation method. The refined mathematical model demonstrates significant conformity with the experimental data at ε > 0.4. Thus, the range of ε > 0.4 is excellent for the calculation applying the mathematical model obtained in this article.

Selim R. S. Eigen modes of Orr-Sommerfeld equation in the developed turbulent boundary layer. Trudy MAI, 2019, no 109,

Spectral methods for solving mathematical physics problems have been intensively studied in the last two decades due to their good approximation properties. Estimation of complex eigenvalues of the fourth order ordinary Orr-Sommerfeld differential equation, which has attracted attention of a number of mathematicians in recent decades, is stipulated by its relevance in the problems of hydrodynamic stability. These methods are considered to be extremely effective for hydrodynamic stability problems where high-precision results are needed. Orr-Sommerfeld type equations are essential for the shear flows analysis, which are important in many fields. One of such areas is climate modeling, when an attempt is made to explain the origin of a mid-latitude cyclone, which in its turn is responsible for creating areas of high and low pressure from which variable weather conditions arise. On the problem of transition from laminar to turbulent flow, all the ideas involved, physical mechanisms, methods used and results obtained are considered, and, if possible, the theory is correlated with experimental and numerical results. It is well known that classical Orr-Sommerfeld eigenvalue problem, which occurs in the linear analysis of the hydrodynamic stability of some basic gas flows, was first solved using the direct spectral method. A numerical study of the eigenvalues of the Orr-Sommerfeld equation for the Blasius boundary layer in the time setting is conducted, and the spectrum of the Orr-Sommerfeld operator is also investigated by Reddy, Schmid and Henningson. In a general mathematical framework, spectral methods for hydrodynamic stability problems are considered, and the Orr-Sommerfeld equation is analyzed, posed with homogeneous boundary conditions that contain a derivative up to the first order.

The collocation method (pseudospectral) based on Chebyshev polynomials is debugged on the Blasius profile and compared with the results of the work Mack.

It is obvious that the increase in the number of Chebyshev polynomials has a significant impact on the accuracy of determining the eigenvalues for the Blasius and Musker profiles. The effect of Chebyshev polynomial degrees on the accuracy of determining the real and imaginary part of the eigenvalues of the first mode for laminar and turbulent boundary layers was considered. The real and imaginary parts of the eigenvalues depending on the wave number for the first three modes of the Orr-Sommerfeld equation for the profile of a developed turbulent boundary layer were obtained This is important for the study of the dynamics (including nonlinear) of Tollmien-Schlichting waves.

Gidaspov V. Y., Kononov D. S. Numerical simulation of fuel combustion in stationary detonation wave in variable cross-section channel with supersonic flow at the inlet and outlet. Trudy MAI, 2019, no 109,

The authors studied the case of (H2 + 0.5O2 + 1.881N2) hydrogen-air mixture combustion in the stationary detonation wave. Analysis of possible flow patterns with stationary detonation wave was performed in chemically equilibrium quasi-single dimensional problem statement according to the technique [8] for a channel in the form of two successively arranged Laval nozzles. In case [8], solution depends exclusively on the radii ratio in the current, initial and minimum channel cross-sections. Passage modelling of a chemically non-equilibrium flow rate through the speed of sound was being realized employing “adjustment of fire” method (algorithm for a singular point passing) [10] using equilibrium solution as an initial approximation. This algorithm allows obtaining a quasi-one-dimensional non-equilibrium stationary solution with a detonation wave in the longitudinal x-coordinate of the l with the given mixture and basic thermodynamic parameters by varying setting coordinate of the detonation wave. Positions of detonation wave are close enough in both equilibrium and non-equilibrium cases. The range of mixture with detonation wave flow rates can be predicted with equilibrium analysis. As in the equilibrium case, three possible solutions with detonation waves in non-equilibrium flow exist in the loop.

Only one solution with detonation wave in the expanding section is stable. This fact was proved by Godunov’s method. The presented quasi-one-dimensional formulation of the problem can be employed for the initial analysis of flows. At the same time, the indisputable advantage of this technique is the high speed of calculations.

Gridin V. N., Smakhtin A. P. Physical modeling of magneto-hydrodynamic processes of powerful tropical cyclones evolution. Trudy MAI, 2019, no 109,

One of the most devastating natural disasters on the Earth are powerful tropical cyclones. As a result, people die, serious damage to engineering structures occur, general violation of the environment ecology in areas exposed to powerful tropical cyclones eventuate. Long-term tropical cyclones monitoring from space revealed a certain geographical regularity in the processes of powerful tropical cyclons origination and development. The main areas of tropical cyclons origination are insular regions of Southeast Asia in the Pacific Ocean and Cape Verde Islands in the Atlantic Ocean near the west coast of Africa. Traditional areas suffering from destructive tropical cyclones are the coastal zone of the United States, Mexico, Cuba, Japan, China, Philippines and in the Far East of the Russian Federation. Similar phenomena in the form of tornadoes are observed periodically off the Black Sea shores in the southern regions of the Russian Federation.

In the areas being subjected to destructive cyclones and tornadoes, people die, houses, bridges and other engineering structures are destroyed.

As the result of tropical cyclones origination, the flights of civil aircraft are canceled, and sometimes destruction of aircraft staying at the airport occured.

The deficiency, at present, of adequate physical model of tropical cyclone origination and development does not allow elaborate a strategy for successful abatement with these natural disasters. The abatement with negative impact of destructive tropical cyclones so far is narrowed down to passive warning of population of possible natural disaster towards ensuring timely people evacuation from the potentially dangerous regions to the safe ones.

The presented article performes an assessment of the atmospheric electricity impact on the powerful tropical cyclones dynamics and demonstrates the possibility of creating an experimental setup for physical modeling of the processes accompanying the destructive tropical cyclones evolution.

Understanding the nature of origination and evolution processes of high-power tropical cyclones will allow create a scientific and technical basis for strategy developing for reliable and effective abatement against these natural disasters, by suppressing the process of powerful air vortices developing at the initial stage of their development.

Voronich I. V., Kolchev S. A., Panchuk D. V., Pesetsky V. A., Silkin A. A., Tkachenko V. V., Nguyen T. T. On aerodynamics specifics of a small-sized aircraft of normal configuration. Trudy MAI, 2019, no 109,

The article presents the results of experimental and computational studies of the model flow-around of a small-sized aircraft of normal scheme in the range of Reynolds numbers of Rе = 2÷8 х 105. Experimental studies were performed in the T-102 TsAGI wind tunnel on the full model and the “fuselage-wing” combination both with and without accounting for horizontal and vertical empennage. The tests were conducted at flow rates of 10÷55 m/s, and the turbulence intensity of the incoming flow was about 0.4% at the speeds of 20 m/s and higher. With this, the range of angles of attack was α = -5÷40° for forward and reverse runs, and the range of slip angles was β = -20÷20°. Special attention is being paid to the efficiency of aerodynamic controls. Basic model has the maximum lift coefficient is Cya max = 1.2 at α = 10÷12°; drag coefficient at zero lift is Cxa0≅0.017; maximum aerodynamic quality Kmax ≅ 21 at Cya≅0.5. The computational study was conducted based on Reynolds-averaged Navier-Stokes equations with closure by turbulence model SST + γ — Reθ. In the described conditions at cruise angles of attack, the laminar-turbulent transition on the wing occurs in the form of laminar separation on the upper surface followed by turbulent reattachment (“laminar bubble”). The Reynolds number affects significantly on the flow at supercritical angles of attack, i.e. with the Re increase, the lift and drag increase along with critical angle of attack. On the most part of the wing the effects of three-dimensionality are weak due to the small sweep. The computed flow fields also revealed the presence of the resource for the model aerodynamic characteristics improving. While computing and experiment, satisfactory agreement was reached on the basic characteristics of the complete configuration for the subcritical angles of attack.

Shishkin S. V., Boikov A. A., Kolpakov A. M. On strength analysis of a Z-shape metal seal with incising elements, being elastic-plastically deformed. Trudy MAI, 2019, no 109,

Flange joints with metal deformable seals are used in piping systems of aviation and space engineering. The article presents the joint with non-contacting flanges, sealed-off by the Z-shaped sealing installing in the unit. As the result of the threaded joint tightening, the flanges close in, squeezing the seal, which elasto-plasticaly deforms herewith. The problem of obtaining a technique for calculating the seal stiffness and its strength analysis is being set. The seal is considered as a profiled axisymmetric ring, subjected to power factors being axisymmetric as well. Theoretical study was conducted, within which framework the K.B. Bitseno theory of rings axisymmetric deformation and I.A. Birger method of variable elasticity parameters were considered with the view of their combining.

Since the seal in the presented problem is subjected to the pure bending, the authors consider its bend stiffness only. The article presents derivation of basic relationships of the design procedure of the Z-shaped seal, elasto-plastically deformed while the joint tightening. It presents the basic assumptions, which allow simplify the technique, making it fully applied. Similar to any other calculation, performed by the I.A. Birger method of variable elasticity parameters, the technique obtained in the article is iterative as well. It can be applied in strength analysis of flange joints while calculating stress-strain state of the Z-shaped seal.

Finally, encompassing rather narrow spectrum of structures types, the research problem solution possesses utterly high potential for further application in similar tasks, where computing of the stress-strain state of the profiled ring being elasto-plastically deformed is required. The main advantage herewith of the obtained design procedure is its relative simplicity due to the fact that elasto-plastical problem is solved completely by the theory of elasticity methods, which is inherited from the above mentioned method of variable elasticity parameters.

Firsanov V. V., Nguyen L. H., Tran N. D. Studying electroelastic state of cylindrical shells from piezomaterials based on refined theory. Trudy MAI, 2019, no 109,

Piezoelectric effect was discovered by the Pierre and Jacques Curie brothers. The essence of the piezoelectric effect consists in the fact that electric charges originate on the surface of crystals of certain classes while their deformation, and vice versa, mechanical strains occur in the crystal under electric field impact. Functional structural elements based on piezoelectrics application are widely employed in various fields of engineering, automation, computer engineering, and especially in the aerospace industry. Such structures are rather technological and allow effectively control their deformations. Thus, studying and computing the stress-strain state of structural elements from piezoelectric materials is an up-to-date task.

The article suggests a version of a refined theory for electroelastic state calculating of cylindrical shells from piezoelectric material. Mathematical model is built based on the three-dimensional equations of theory of elasticity. The problem of reducing three-dimensional equations to two-dimensional ones is realized through representing the required displacements by polynomials along the normal coordinate two degrees higher with respect to the classical theory.

A system of differential equations of equilibrium in displacements and potentials was obtained using Lagrange variation principle. Operational method, based on Laplace transform, and Maple software are employed while solving the formulated boundary value problem. Shell deformations are obtained by geometric relationships, tangential stresses are determined from the Hooke law relationships, and transverse stresses are determined from the equilibrium equations of three-dimensional theory of elasticity. Electric potential distribution on the shell surface is obtained by direct integration of the electric field intensity expressions.

A cylindrical shell from PZT piezo material is being considered as an example. Let us apply an electric potential on the upper and lower surfaces of the shell with hinged-fixed edges on the boundaries. Based on the computational result, the article demonstrates that with the absence of mechanical loads, and electric potential action only on the shell surface the stress-strain state existed inside the shell.

Comparing the results obtained in the presented work with the classical theory data allowed establishing that while studying electroelastic state of the cylindrical piezo shell near the zones of the stressed state distortion, for example, near hinged edges, the refined theory should be employed, since maximum stresses in this zone were being substantially refined.

In the boundary zone, transverse normal and tangential stresses, which are neglected in classical theory, appear to be of the same order with maximum stress values corresponding to the classical theory. Such high levels of additional stresses should be accounted for when evaluating the strength and durability of shell structures.

Gerasimchuk V. V., Ermakov V. Y., Telepnev P. P., Shapovalov R. V. Experimental validation of regulated magneto-fluid vibration protection system concept. Trudy MAI, 2019, no 109,

The article is devoted to the experimental studies on vibration load reduction to an acceptable level of the space complex structural elements from the disturbances by devices with moving masses by a magneto-fluidic vibration protection system with an adjustable elastic-damping characteristic

According to the authors’ opinion, namely the magneto-fluidic vibration protection systems are capable of reducing the vibration load of scientific equipment to the levels that ensure its proper functioning under the impact of internal disturbances sources, such as devices with moving masses. Magneto-fluidic vibration protection systems with adjustable elastic-damping characteristics allow direct coupling of electric control channels with the actuating devices of the vibration protection system without intermediate mechanical devices. The high-speed response is ensured thereby, and the structural scheme of the vibration protection system is simplified.

Changing current in the electromagnetic control coil, the experimenters controlled magnetization of the magneto-rheological suspension and, adjusting the elastic-damping characteristic of the vibration protecting system in relation to the movable masses rotation speed, they managed to:

– “cut back” peak values of the force-torque characteristic in the low-frequency region in the area of resonant peak of vertical oscillations to the levels below the allowable one;

– reduce peak values of the force-torque characteristic by 40% in the region of the force-torque characteristic resonant peak of flexural-and-torsional vibrations.

The authors experimentally affirmed the concept of possible reduction of the vibration loading on scientific and precise equipment of the space complex of parasitic disturbing impacts from the force-torque devices with movable masses throughout the whole range of their cranking speed by the magneto-fluid vibration protection system with adjustable elastic-damping characteristic.

The vibration isolation effectiveness with simultaneous required vibration loading ensuring can be achieved by “blocking” the vibration isolator operation in the low-frequency region and excluding generated hazardous manifestation of vibration isolation resonant peaks and “turning-on” the vibration isolation effect of the vibration protection system in both medium- and high-frequency ranges.

Shmachilin P. A., Shumilov T. Y. Matrix beam-forming scheme of a digital antenna array. Trudy MAI, 2019, no 109,

The presented article regards issues of developing and modelling a digital beam-forming architecture of a digital antenna array based on a problem of homogeneous electro-magnetic wave incidence on a curtain of a linear digital antenna array. It presents requirements and basic suppositions for realizing modelling process of digital beam-forming algorithm based on matrix beam-forming scheme. Analysis of previous generation transceivers structures and their differences from the structures of modules, which could be built based on the up-to-date technological level, was performed. The issues of digital antenna arrays building, employing state-of-the-art units for digital signal processing, involving functional schemes and data processing algorithms of higher-end, are tackled as well.

The article offers a modification of the of matrix beam-forming algorithm, employing discrete Fourier transform, as well its modification, ensuring numerical simulation modeling. A feature of the beam-forming scheme algorithm operation is that the process of beam forming is performed separately for each spectral component of the input digital signal. It allows eliminate the beam frequency variation effect, and improve thereby directional and frequency properties of the array as a whole. The article considers all steps of the input digital signal conversion throughout the beam-forming scheme. Methods for phasing and spectral matrices computing, as well as their application for digital signal computing at the output of the beam-forming scheme, are presented as well.

The article presents a technique for the digital direction pattern and its characteristics evaluating for digital antenna array with the digital beam-forming method under consideration. Numerical simulation results of the system operation, including parameters evaluation of the direction pattern for harmonic input signal and it spectrum, as well as examples of digital signal and its spectrum at the output of the beam-forming scheme being modelled are presented.

It is shown that the presented algorithm ensures forming of the angle selectivity properties of the antenna array.

In conclusion, considerations on the possibility of application of up-to-date high-performance hardware for analog-to-digital conversion and signal processing are presented.

The results of the presented work can be applied for developing state-of-the-art and prospective digital antenna arrays for communication or radar systems. Such kind of systems impose high requirements on the processed signal bandwidth, number of ranges of adaptive radiation pattern forming and possibility of multi-beam reception.

Volkov A. S., Muratchaev S. S., Kulpina Y. A. Developing simulation model of two-rank MANET Network. Trudy MAI, 2019, no 109,

Decentralized mobile MANET networks (Mobile Ad-hoc Network) are self-organizing radio networks with a topology without basic stations. The presented work is devoted to the study of MANET networks performance improvements. Mainly, the two-rank MANET network concept is considered. It supposed that single-rank MANET network conversion into the two-rank topology would improve the network operation in a part of such parameters as throughput and average latency. Many merits and demerits, the main from which was the small coverage zone and its impossibility of widening by technical means, were revealed while studying properties of this class of networks.

A simulation model of the proposed two-rank architecture of the MANET network was developed in the Network Simulator 3 simulation environment. Based on the simulation results, two graphs were plotted, namely, the dependence of the average latency value and the dependence of the batches delivery coefficient on the data transfer rate.

Modeling was performed in three stages. The first stage was the MANET ad-hoc network consisting of 350 nodes modeling. Based on the results, a graph of the network bandwidth dependence on simulation time was plotted. The values of average latency, throughput, a share of lost batches and average route setting time were obtained as well. The second stage was the MANET two-rank network simulation. Characteristics of the network interaction similar to those at the previous stage, and a graph of the throughput versus simulation time were obtained. The third stage consisted in both single-rank and two-rank MANET networks simulation with gradual data transfer data-transfer rate value changing. Two graphs were plotted by the results of the simulation. They are the dependencies of average latency and batches delivery coefficient on the data-transfer rate. The effectiveness of the proposed two-rank network topology allows achieving an average gain of 15-30% compared to the classical MANET networks representation in parameters of throughput and average network latency. Basing on the simulation model operation, inferences can be drawn on the communication quality improvement practicality by the two-rank topology implementation in the MANET network.

Zhitkov S. A., Ashurkov I. S., Zakharov I. N., Leshko N. A., Tsybulnik A. N. Detecting technique for aerodynamic target moving along rectilinear trajectory in space. Trudy MAI, 2019, no 109,

The article presents a technique for rectilinear trajectory detecting of an aerodynamic target in space based on the Hough transform, which can be used in modern radar systems. This technique allows solving the problem of trajectories detection of aerial objects in conditions of low energy availability of radar signals.

A technique for the rectilinear trajectory detecting of an aerial object in space is based on the tracking-before-detecting technology employing the Hough parametric transform. The article suggests an option of this technique realization for ground-space multi-position radar system for aerodynamic targets detection. A technique for Hough transform application for straight lines selection in space consisting in 3D image projection onto orthogonal planes, rectilinear areas extraction on these planes and backward merge of the selected fragments into a straight line in space was developed. Both algorithm of space-time marks selection, belonged to the selected straight line, and algorithm for identifying segments on a plane into segments into space were applied. Detection quality indicators computing was performed, and an optimal threshold for decision-making on the trajectory detection was selected on their basis. The article presents the results of the suggested technique operation obtained by modelling in Matlab.

The suggested technique for detecting a rectilinear trajectory of an aerodynamic target in a ground-based-space multi-position radar system allows detecting rectilinear trajectories of aerial objects in space at low values of the signal-to-noise ratio.

Chistyakov V. A. Angular coordinates monitoring system of radio emission source for space communication equipment. Trudy MAI, 2019, no 109,

At the beginning of radio communication systems development, the main task consisted in establishing contact between two subscribers. However, improvement of radio facilities and increase in their number in all over the world, has led to the need of ensuring an error-free information exchange through communication channels.

Various noise protection techniques are used to solve this problem, and adaptive control of the antenna directional pattern in particular. However, in conditions of non-stationary interference, noise immunity techniques can be realized, if information on radio emission sources location was previously obtained. It is well-known that spectral methods (super-resolution methods) for processing signals, received from the antenna array (AA) outputs, allows estimates forming of the radio emission source angular coordinates rather accurately.

The super-resolution methods are splitted into two groups according to the scanning technique, i.e. the ones with sequential and parallel direction finding of radio sources.

The first group includes such techniques as thermal noise technique, Keipon method, and method of multiple signals classification (MUSIC). The output goal function of such methods represents continuous dependence of the output signal power on the angular position. In the space scanning process by mathematical reference signal, maximums of the objective function correspond to the angular coordinates of the radio emission sources. These methods are applicable to antenna arrays of any configuration.

The second group of methods with parallel scanning includes the Pisarenko, the subspace rotation (ESPRIT), and the ROOT-MUSIC methods. However, for practical applications, structural limitations on the antenna arrays shape are imposed on this group of methods.

A method for multiple signal classification (MUSIC) is employed for angular coordinates monitoring system realization in the presented work. It possesses the best of all resolution from the group of methods with sequential space scanning, and is applicable for antenna systems of any configuration.

The MUSIC method operation consists in employing the signal and noise subspaces of the correlation matrix input signals, with which the objective function evaluation and direction-finding peaks formation proceeds

The process of the angular coordinates monitoring system operation is performed based on 25-element flat rectangular antennae array. Both narrow-band and broadband signals are employed as radio waves. The result of the work is formed direction-finding peaks obtained in the course of the studies. Evaluation of qualitative characteristics of this method was performed as well.

Zinoviev Y. S., Mishina O. A., Zakharov A. Y., Hatanzeiskaya M. A. Detection Characteristics Estimation Techniques of Gground-Based Electro-Optical GEODSS system. Trudy MAI, 2019, no 109,

The issues of near and outer space studying are actual fr om both scientific and practical viewpoint. From scientific viewpoint, it means studying the Solar system (including asteroids, comets, distant Galaxies). From a practical point of view, this is the control of space objects and the monitoring of the contamination of near-earth space with space debris. As for practical viewpoint, it means space objects control, and monitoring near space, littered by space debris.

To solve these problems, systems of outer space control are being developed in Russia, the United States and other countries. An important component of the US space control system is the ground-based electronic-optical deep space probing GEODSS complex (GEODSS — Ground based Electro-Optical Deep Space Surveillance).

Based of well-known tactical and technical characteristics accessible in open information sources, the article considers a technique for detection characteristics estimation of photometric channel of ground-based Electro-Optical GEODSS system.

In contrast to the well-known works, the presented article accounts for significant unevenness of the quantum efficiency of modern photodetector devices operating in visible range. The assessment is performed according to reference objects in geostationary orbit. Estimation of possibilities for applying Johnson bands for solving spectral selection problems is also considered. Basic expressions for computing both the integral signal-to-noise ratio and in Johnson bands are given.

To assess the energy parameters of the telescope, two types of reference objects with specified characteristics are considered, namely a mirror and diffuse spheres.

Photometric channel modeling of the optical-electronic system GEODSS allowed determine the main detection parameters of reference objects in geostationary orbit. The article demonstrates that this opto-electronic system is capable to detect a mirror sphere of 5.6 cm in diameter in the geostationary orbit at accumulation time of no less than Ta = 2 s, while it detects a diffuse sphere of the same diameter at accumulation time of Ta = 1 s.

The worst detection conditions are formed in the 800–1000 nm band, wh ere the quantum efficiency of the CCID-16 detector is low (n < 0.35). As the result, even at Tn ~ 50 s, the detection conditions are not met.

However, in the three Johnson bands (400–500 nm, 500–600 nm, 600–800 nm), the optoelectronic system works efficiently with both mirror and diffuse spheres. Thus, the optoelectronic system receives spectral characteristics of space objects and can solve the problems of their recognition.

Glushchenko A. A., Khokhlov V. P. A method for a spacecraft maneuver detection based on current trajectory measurements. Trudy MAI, 2019, no 109,

Two main tasks are being solved in the process of space surveillance. These are space objects detection and their tracking to maintain necessary accuracy of the orbit parameters. Unpredictable parameters changes of a space object movement, caused by the propulsion system starting (maneuver), spatial orientation changing or destruction, can become the cause of tracking process failures. To avoid such situations, timely detection of such unpredictable movement parameters changing while trajectory changes processing and solve the problem of a space object movement parameters refinement are necessary.

Analysis of known ways of unpredictable changes detecting in movement parameters of space objects revealed that with information limiting existing in practice, the quality of space monitoring problems solution can be ensured through the application of trajectory measurements processing methods with the space object maneuver detection.

Considering practical implementation of such method, employed in the process of outer space monitoring, reveals that maneuver-detecting problem is solved currently with acceptable quality under the standard conditions of space objects tracking. However, in some cases, such as emergency (off-normal) situations onboard an important spacecraft, the requirements for operativeness of supplying a customer with information on a spacecraft movement parameters may be significantly increasing.

The article considers a method for detecting and determining parameters of a spacecraft maneuver performed on the time interval between the two adjacent stages of its monitoring by measuring tools. This method employs a spacecraft orbital parameters changes as informative signs for maneuver detection. Maneuvers parameters determining (maneuver time and speed increment) is being performed using relationships of the linearized spacecraft movement model. Based on simulation, evaluation of its application effectiveness while maneuvers parameters of low orbit spacecraft detecting and determining was performed.

In contrast to the known ones, the advantage of the regarded method consists in the possibility of increasing efficiency of both maneuver detecting and its parameters determining in conditions of the existing information limitations. The results obtained using the method for maneuver parameters evaluation can be used to solve the problem of a spacecraft movement parameters refinement.

Zakharov R. S., Skvortsov B. V., Taipova D. R. Extra errors analysis of capacitive sensors of launch vehicles fueling system. Trudy MAI, 2019, no 109,

The article regards the problem technological equipment unification for launch vehicles of «Soyuz» family. This problem consists in the fact that in the process of modernization, a vast nomenclature of spaceport equipment and launch vehicles modifications appeared. However, their compatibility is not foreseen herewith at present, i.e. the newer modification of a launch vehicle cannot be connected to the spaceport equipment, and, vice versa, technological equipment of new generation does not fit for launch vehicles of older modification. Besides, simultaneous maintenance of several equipment complexes increases maintenance time and cost. This problem is now being solved by installing a new generation equipment at both launching and technological complexes, leaving the old kit at its place. However, this kind of modernization leads to stoppage of regular operation of launching and technological complexes for the time of installing and testing. Different technological equipment kits have both various operational documentation and differing operation technologies, which enhances requirements to maintenance staff. An operator of the same system of various modifications has to know all specifics of their operation. In case of emergency, he must understand clearly operation logic of that particular system, which he operates at this particular moment. It leads to technical maintenance costs increase, and, thus, to a rocket launching costs increase as well.

As part of this problem solution in the field of equipment for the of fueling level measuring, the article proposes a universal capacitive sensor of the of fueling level with a compensation section for the «Vostochny» spaceport, and the scheme of its connection, as well as the analysis of extra errors of capacitive sensors.

As the result of additional errors studying, associated with the fuel both temperature and environment changes, an analytical expression determining the total temperature coefficient of the level sensor, linking up temperature coefficients of component materials, and fuels under control, was obtained.

Novomeisky D. N., Kulikov A. V., Piganov M. N. Algorithm for film structures machining process by torch discharge. Trudy MAI, 2019, no 109,

A limit of mass-size indicators was exceeded while developing a variant of onboard defense complex (ODC), which included the active jamming radar station. In this respect, the decision was taken to realize the ODC control and monitoring unit based on another structural basis, i.e. in the form of microchips with irregular structure. Such microchips include both thin- and thick-film substrates with high-precision resistive elements. The thin-film substrates are produced by the technique of vacuum-heat sputtering on a glass ceramic substrate. The thick-film substrates are fabricated by the metal-screen printing technique with subsequent burning-off. Schematic design stage revealed while workable samples testing that laser adjustment operation did not ensure the required reliability of film-elements. Studies of other adjustment techniques were conducted. As the result of experimental studies, the adjustment technique for resistors processing by the high frequency torch discharge was selected. The main advantage of this method is the moderate temperature in the processing area. This excludes subsequent element material degradation processes. Further studies confirmed high reliability of film resistors after adjustment. Simulation of this technological operation was performed.

The algorithm for resistors adjustment by processing them with the high-frequency torch discharge is presented. The feature of this method is that it allows simultaneous of the element mounting to the zone of adjustment and a gap size calculating. Thus, the gap computing time is not accounted for directly during adjusting process. The program allows determining the gap values dependencies on a number of parameters of the affecting system. Computing results herewith are being presented in the form of graphs, which can be used afterwards. Besides, computing of other parameters, included in the adjustment model, is provided.

The algorithm ensures high precision of calculations and can be used for process automation of microchip elements adjustment, and solving the problem of this operational control of the process The program is written in LabVIEW language. Mathematical model of microchips film-elements adjustment by the torch discharge was used while developing the algorithm and calculation program.

Gainanov D. N., Chernavin N. P., Chernavin P. F., Chernavin F. P., Rasskazova V. A. Convex hulls and convex separable sets in the multiclass pattern recognition. Trudy MAI, 2019, no 109,

The paper is devoted to the multiclass pattern recognition problem in its geometry statement. Such problems are often occurring in various areas of financial mathematics, diagnosis and forecasting. There is proposed a geometry based approach connected with separatebility properties of convex hulls of sets of finite-dimensional space.

The multiclass pattern recognition problem under consideration is to construct a decision rule to assign an arbitrary input point to some class of the training sample. The main idea is to construct a convex hull for each class of training sample and then to assign an input point to such a class which convex hull will be the most closely to the corresponding point. It is shown that in case when classes of the training sample do not intersect (by points), the proposed approach entails the uniqueness of the decision rule. In general case, it is required that the convex hull of each class does not contain points from other classes. The problems, which training samples satisfy this condition, were called as convex separable set solvable.

The results of computational experiments show that a number of classic pattern recognition problems are convex separable set solvable. In particular, there are presented in the paper the results of computational experiments using test data of the public library. As it turned out, the Iris Fischer problem – fundamental in this particular class – is a convex separable set solvable. Moreover, the constructed decision rule provides the classification of the training sample corresponding to the best known solution. This non trivial fact allows one to expect a high application efficiency of the proposed approach.

It occurred that the hardest stage of the proposed approach is to construct convex hulls for training sample. For these purposes, there were used well known Gale transformation for a sequence of points and after that a convolution S. N. Chernikov’ algorithm to search a minimal infeasible systems of an infeasible system of linear inequalities. These auxiliary algorithm is based on the previously proved dual relationship between hypergranes of a convex polyhedron and multiindices of minimal infeasible systems of an infeasible system of linear inequalities. The corresponding procedure were described in the paper in frame of the small academic example.

It should be also noted that the formalization of the class of convex separable set solvable problems of multiclass pattern recognition, as well as the further development of methods for constructing a convex hull in a finite dimensional space, are objects of further research.

An application meaning of the results obtained, in addition to the above mentioned problems of financial mathematics and forecasting, are also connected with important industry problems such as, for example, metallurgical production. One of the most important problem in such production is to reduce manufacturing errors due to reassignment or complete termination of irrational technological routes. In this regard, the direction of further research could be associated with mathematical modelling, and its continuation in frame of multiclass pattern recognition, to solve problems on the operational technological routes control in the discrete production (in particular, un the metallurgical production).

Naumov A. V., Martyushova Y. G. Distance learning system adaptation based on statistical processing of the results of users activities. Trudy MAI, 2019, no 109,

The article regards the of statistical analysis tools of the distant learning systems (DLS) operation analysis aimed at adapting user’s individual tasks forming process to create his individual training trajectory and control of a compromise of answers. Probabilistic model of the time consumed by a user for the responses to the task is taken as a basis for the user responses compromizing algorithm. The Van der Linden model with log-normal response time distribution is used herewith. The left-hand confidence interval is formed with its aid, and in case, if the user’s response goes beyond its boundaries, a signal to the system administratof is generated on possible compromizing of the response. A certain set of system administrator actions exists herewith based on the signal occurrence, namely the task substitution, tutors’ face-to-face cpnversation with the user, etc. The DLS user individual trajectory forming algorithm is built based on the Rush Model of the probability of right response of the user to the task. The model parameters are the level of the task complexity and the level of the user’s abilities, which are assessed by the maximum likelihood method. User’s individual trajecroty is formed stage-by-stage. Individual task fo the user is formed for each course section by integer programming problem solving method, which parameters are the total complexity level selected by the administrator, and evaluation vector of tasks complexity, obatained based on the Rush model. Individual learning trajectory correcion is performed by limitations in the integer progamming problem, controlling the total complexity of the task, and by user ranking method by the user progress categories with the Rush model.

Depending on the category that the user enters, the administrator selects a specific level of total block of tasks complexity for the individual training trajectory generation task. The proposed algorithms for the individual training trajectory forming of the DLS user and compromizing his answers are implemented in the mathematical support functioning package of the MAI DLS CLASS.NET.

Simonov A. S. Simulation model of high-speed Angara communication network with kD-tor topology. Trudy MAI, 2019, no 109,

The article describes the implementation and experience in application of a simulation model of the Angara high-speed communication network, designed to build multiprocessor computing systems with high performance scalability on its basis.

The studies performed with the simulation model allowed working-out basic solution on the router micro-architecture; algorithms of its components operation; a batch format; basic operation; routing and arbitration algorithms; perform optimization of the router architecture parameters, including basic relation on throughput capabilities, network connectiveness, memory buffers size; balance throughput capabilities of the router components, and perform verification of the custom ASIC. Based on the results of the simulation, the final technical appearance of the router was formed, implemented both in custom ASIC and in Angara communication network equipment based on it.

The experience gained can be employed to create perspective samples of network equipment.

Makhnev M. S., Fevralskikh A. V. Verification of results of determining rotational derivative of aircraft heel in a wide range of angles of attack. Trudy MAI, 2019, no 109,

The article gives an account of aerodynamics numerical modelling to determine rotational derivatives of aircraft heel at angle of attack values range from – 5° to 90°. The aircraft reversed motion is being modeled, with this, the incident flow velocity vector and angular rotational speed vector are collinear. Numerical modeling (CFD modeling) of aerodynamics is based on solving the Reynolds-averaged Navier-Stokes equations, and closed by k-ε Realizable turbulence model, by control volume method. For CFD modeling of laminar-turbulent transition near the aircraft surface, the presented work employs wall functions of the Enhanced Wall Treatment type.

The results of stationary coefficients determining of aircraft aerodynamic forces and moments by CFD modeling are in good agreement with the results of experiments with a scaled aircraft model in a wind tunnel. Rotational derivative values of the roll moment coefficient obtained from the of numerical modeling and experimental results are also in good agreement with most values of the aircraft angles of attack. Values mismatch of the lateral force derivatives and the yaw moment with respect to the angular roll velocity obtained by different methods is determined by the corresponding aerodynamic disturbances and measurement errors during their experimental determination. For further research trend, the authors consider reproduction of experimental conditions of a wind tunnel in CFD modeling, such as structures of model mounting, consistency assessments of experimental data recording with the model rotation frequency and eddy formation frequency. As a whole, the results of the study reveal that CFD modeling allows determining not only coefficients of aerodynamic forces and moments, but their rotational derivations by the heel velocity. However, conducting of extra experiments seems up-to-date for verification of various approaches to rotation modelling.

Mustafaev T. A. Studying hail shot characteristics and solving trajectory problem of uncontrolled flight of an arbitrary shaped solid body for aircraft engines full-scale testing on durability. Trudy MAI, 2019, no 109,

Along with the development of computational methods for studying the strength characteristics of aircraft structural elements, a field experiment is widely used, reproducing the real impact of birds on aircraft structures at the collision in flight. The presented article is devoted to the study of the hail shot characteristics and trajectory problem solution of uncontrolled flight of an arbitrary shaped rigid body for full-scale tests of experimental and serial aircraft engines on durability by test bench, simulating the hit by birds or hail.

The full-scale tests on of large birds’ ingress in the aircraft engine, which, according to current regulations, are performed on a running engine, or rotating impellers of fans or compressors on the test benches are extremely cost intensive. Thus, it is expedient to perform computing analysis of the working blades resistance to the impact interaction with a bulky bird and hail prior to the full-scale tests conducting.

Test bench installations for conducting tests on blades resistance to impact interaction with a bulky bird or hail should maximally reflect conditions of real interaction of full-scale impeller with a bird or hail. They should also satisfy a lot of hardly compatible requirements, such as mathematical model for computing internal and external ballistics of the test bench, trajectory problem solution of a solid body uncontrolled flight, which we will try to solve in the presented article.

Vinogradov A. V., Borukaeva A. O., Berdikov P. G. The mathematical model of the motion of the aircraft and ballistic algorithms for calculating the nominal and perturbed motion parameters ballistic aircraft. Trudy MAI, 2019, no 109,

With a view to aircraft and rocket engineering rapid development, considerable complication of aircraft design and cost intensity of its developing, the effectiveness significance at the early stages of design, when aircraft basic structural characteristics are being selected and nominal parameters of its movement are determined, increases.

Occurrence of small asymmetries, as well as small thrust eccentricities for aircraft with power pack, due to technological errors while aircraft components fabrication and their assembly, is possible during production process of various types of aircraft.

The article deals with the algorithms of nominal and perturbed motion parameters of ballistic aircraft while operational change of target marking in flight. The presented algorithms are based on an aircraft mathematical model, which, in its turn, allows ensuring achieving the target movable point in condition of operational changes of target marking.

The applied directedness of the guidance theory is confirmed by the fact guidance system, materialized as the result of the guidance theory application to solving specific problems concerning control of the aircraft center of mass, is necessarily a part of the ballistic aircraft control system.

Equations of motion (basically, Cauchy differential equations) and a technique for differential equation solving form the basis of the mathematical model. The mathematical model complements gravitational field characteristics, atmosphere characteristics, the aircraft dynamic characteristics, and its power pack characteristics.

In the general case, the problem of mathematical modelling of the elastic flying machine dynamics is split into, at least, two more problems. The first one is direct modelling of the elastic flying vehicle behavior, determined by the interacting forces, and the second is accounting for action of flowing forces and moments, stipulated by the elastic flying vehicle deformation, and control system operation.

The presented article considers theoretical basics of the approach to the solution of the set problem, based of real aircraft structure substitution by the equivalent scheme and its realization for the rockets as the simplest from the sketchness viewpoint class of aircraft. Accounting for the aerodynamic forces and moments herewith, caused by the aircraft elastic deformation, is realized based on the simplified stationary hypothesis.

Bal M. A. Model and algorithm developing for efficiency assessment of anti-missile defense overpowering by hypersonic flying vehicle with regard for counteraction of aviation complex. Trudy MAI, 2019, no 109,

The article proposes an improved model and algorithm for effectiveness assessing of anti-missile defense overcoming by hypersonic aircraft with regard for aviation complex counteraction. To assess the overcoming effectiveness, a corresponding model of aviation anti-missile defense complex effort was proposed. Setting of matrix game between a hypersonic aircraft and anti-missile aviation complex with effectiveness matrix filling out for subsequent selection of the most effective, from the viewpoint of antimissile defense, flight path was proved. The developed model and algorithm relevancy are emphasized by the fact that they can be employed for the process modelling of anti-missile defense overcoming by the hypersonic aircraft and its effectiveness assessment with regard for the aviation complex counteraction at any option.

Hypersonic aircraft with necessary aero-ballistic quality and capable of performing atmospheric maneuvering at rather long distances from the object to be protected, are effective enough means for target hitting, covered by conventional and prospective anti-missile complexes of the missile defense system.

The idea of aircraft component introduction into missile defense system is not novel. The possibility of a spacecraft destruction by the missiles launched from aircraft complexes was previously considered. Since the spacecraft moves at present over the paths with calculated parameters, aiming at them is being considered as stable.

As for the hypersonic flying vehicles problem, their destruction by aviation systems of missile defense system will obviously be much more complex. Nonetheless, it is viable in principle, and in a number of cases, its fulfillment from the enemy viewpoint may be more effective than performed by ground-based and/or marine missile defense system complexes.

Panteleyev A. V., Luneva S. Y. Numerical technique for solving fully fuzzy systems of linear equations. Trudy MAI, 2019, no 109,

The article considers the problem of numerical solution of a linear system of equations with a fuzzy rectangular matrix and a fuzzy right-hand side. An uncertainty of the parameters, described by the intervals of possible values, presents, as a rule, in the practice of engineering and economic calculations. Besides, the level of confidence, set in the fuzzy set theory by the so-called membership functions, may be assigned to the numerical value from the interval. One of the possible types of membership functions are triangular ones, which set triangular fuzzy numbers. The authors suggest employing the triangular numbers description in the form of an average value and deviations from the average value. A technique for fully fuzzy system solution, employing the more accurate formula for the fuzzy numbers product, correct in the absence of the assumption of scatter smallness around the average value, as well as the apparatus for obtaining pseudo-solutions of the systems of linear algebraic equations, was obtained in the article. The class of problems to be solved is limited to finding positive solutions of systems of linear equations, provided that the fuzzy numbers included in the matrix of the system and the right-hand side are also positive. Quite stringent condition were obtained, under which the solution of the system is positive. The article presents four examples, illustrating the proposed method application for systems with matrices of various sizes and ratios of the rows and columns number, as well as comparison of the obtained results with solutions obtained using well-known formulas.

Shikhin S. M. The task of data monitoring of spacecraft operation control system with the problem area covering. Trudy MAI, 2019, no 109,

The state of the up-to-date software tools and objective hardships of ensuring data control of the space equipment planning and control system (SE PCS) and its lifecycle management, related to the problem area complexity, require improving approaches to the corresponding problems solution. The problem of software and hardware tools (SHT) verification and their reliability is not yet solved in the general case. It seems that the reason for this is the lack of modelling and full coverage of the entire wide problem area, including both applied tasks and corresponding SHT. Thus, it is necessary to cover the entire problem area to ensure data control, and their management based on considerable data and knowledge on entire problem area under consideration. Data control should be performed over the entire life cycle of the spacecraft equipment planning and control system by modifications of various types of software components

In the case under consideration, such an approach requires a uniform formalization of the entire complex, non-uniform, but internally unified problem area, as applied to the task of data monitoring of the spacecraft control and its life cycle managing system. For such formalization ensuring, the author suggests radical modelling and RADICAL universal language of radical schemes. Thus, the goal of the presented work is brief description of the approach to ensuring data control of the spacecraft equipment planning and control system based radical modelling.

In general, the proposed approach is aimed at the wide application of software and hardware, standardization of the problem area of the spacecraft SE PCS and other complex ASs, and their intellectualization, i.e. the ability of solving contingency situations and self-learning on their basis.

Korovaytseva E. A. Mixed equations of the soft shells theory. Trudy MAI, 2019, no 108,

The article proposes a new variant of resolve relationships of the soft shells theory. This variant differs from the existing ones by the numerical realization convenience. Both equations of large deformations theory and technical theory of soft shells are considered. The principle of virtual displacements is applied to derive equations of the shell equilibrium. Expressions for components finite deformations are used in the V.V. Novozhilov’s form. Functions of generalized forces were introduced to the final notation of variation equation. It allows setting down the equations of the soft shells theory in the form used while boundary problems formalization. As the result, the system of equations describing the soft shells behavior at large deformations includes the equations of equilibrium, additional projection relationships, dependencies, describing the true forces reduction to the initial state metric, and geometry relationships. For the system of equations closure, physical relationships, linking real forces with deformations, are used. Thus, the finally composed system consists of 23 equations with 23 unknowns.

While considering the technical theory of soft shells, deformations are assumed small, and forces, acting in the shell being deformed, are represented as a sum of two terms, corresponding to the main and additional stress states. The initial state geometry is considered as known. Forces and displacements corresponding to the additional state are being determined from the system of equations, obtained as the result of variation equation components linearization relative to the main state. As in the case of large deformations, functions of generalized forces are introduced for the additional state. As the result, a system of three equations of equilibrium is formed for the main state. The system of equations for additional state consists of 18 equations, and includes equilibrium equations, additional projection equations, geometrical equations and physical relationships. The system is supplemented by the boundary conditions.

The obtained relations are not pretending on fundamental changes or add-ons, but unlike the known relations they do not require reducing to a single equation relative to one variable. They can be reduced to Cauchy normal form, convenient for application of numerical methods for direct integration, and standard methods of ill-conditioned boundary problems solution.

Phone H. K., Sysoev E. O., Kuznetsov E. A., Min K. H. Life cycle durability prediction of high-pressure pipelines under the impact of low-cycle loads. Trudy MAI, 2019, no 108,

Nowadays, high-pressure pipelines are widely employed aircraft and machine building in hydro-gas and fuel systems. While machines and mechanisms production and operation much attention is paid to control of high-pressure pipelines made of high-strength steel, as well as aluminum and titanium alloys. Pipelines operate under conditions of low-cycle loading impacts from the internal pressure, stretching and torsion, which affect significantly on their long-term strength at various types of the stress-strain state and shapes of loading cycle. Under real operation conditions, these structural elements operate under both linear and complex stressed states. A serious problem of materials consumption and cost reducing arises in the course of designing, ensuring herewith the strength and durability of the part. For the structures failures prevention, overstated strength margins are specified, and, as a consequence, increase their materials consumption and cost. However, with this approach microstructure damages of the material and abrupt change of the material strength while damage accumulation while fabrication and operation are not accounted for.

The problem solution consists in setting quantitative and qualitative dependencies of the material microstructure changing and long-term strength, which defines structural materials durability and residue resource of object under operation.

The acoustic emission (AE) method is the most suitable for these changes recording. The AE reflects microstructure reconfigurations of structural materials under the impact of any loads, but calculations should account for the most informative AE signals from the defects, which are not recovered during further operation, with fractal dimension of attractor signal of 1 ≤ D2attr ≤ 6 .

The article considers technique of durability forecasting of the pipelines under the impact of low-cycle loads at different loading trajectories in the two-dimensional stress space in a plane stress-strain state employing the acoustic emission method. The problem of determining the high-pressure pipelines durability depends on the dangerous damages accumulation in the structural material of pipelines as the result of plastic deformations accumulated from low-cycle loads, characterized by high stresses, various cycle forms and loading trajectories. The residual life evaluation of the existing pipelines is currently based on the latest achievements in the field of fracture mechanics, metallurgy, non-destructive testing methods, and current design standards for strength and conditions of actual operation. The existing methods herewith do not account for microstructure evolution of the structural material in real time. The acoustic emission method allows accounting for transformation of the structural material microstructure in real time, and predict the residual life.

The proposed method allows significant reduction of the laboratory tests number for predicting the high-pressure pipelines durability under the impact of low-cycle loads at various loading trajectories.

Khatuntseva O. N. Determining critical Reynolds number of laminar-turbulent transition in a flat Poiseuille problem based on “discontinuous functions” method. Trudy MAI, 2019, no 108,

The existing methods for determining critical Reynolds numbers of laminar-turbulent transition are related mainly to determining the loss of linear stability of laminar flow mode [1-3]. However, the attempts for resolving the best-known “classical” problems of the hydrodynamics are far from the success. Thus, the Hagen-Poiseuille problem and the flat Couette problem possess linear stability for any Reynolds numbers. There is a limitation on stability for laminar flow mode of the flat Poiseuille flow. However, the critical Reynolds number for stability loss computed by Orszag is 5772, which is exceeds experimental data almost six times.

The presented article continues the author’s circle of publication devoted to the solution of the hydro-dynamical problems, assuming an analytical approach existence for their consideration. The possibilities of “discontinuous functions” method application for theoretical estimation of the critical Reynolds number value of laminar-turbulent transition for the Hagen-Poiseuille problem and the flat Couette problem are studied in [17-18]. The method may be applied in the cases, when different functions specifying various physical processes exist, such as laminar and turbulent flow modes, as well as the jump-like transition from one physical process to another.

The author succeeded to analytically define functions, describing quasi-stationary turbulent and stationary laminar flow modes for the Hagen-Poiseuille problem and the flat Couette problem. These problems solutions were obtained at the cost of accounting for the entropy production in the Navier-Stokes equations, stipulated by stochastic pulsations excitation in the fluid flow. The similar approach to the velocity profiles determining both in laminar and turbulent flows applied in [19] for the flat Poiseuille problem solution. The presented work is devoted to the Reynolds number critical value determining by the “discontinuous functions” method in the for the flat Poiseuille problem. The critical value for Reynolds number at which laminar to turbulent flow mode transition was possible, was found. The article presents the results comparison with the available experimental data.

Zagordan A. A., Zagordan N. L., On special generalized coordinates application for studying joint flexural vibrations of the blades of the main rotor, which is fixed on the elastic-damping support. Trudy MAI, 2019, no 108,

The article considers bending vibrations of the main rotor blades, linked through the “pylon–main rotor” support, as naturally stranded rods, in both traction plane and rotation plane. The general system of equations of vibrations for the “main rotor–support” dynamic system, and assumption resonant diagrams of the main rotor with corresponding amplitude-frequency characteristics in the form of dependencies of changes of coefficients dynamic by frequency for the loads, passing to the main rotor shaft, are presented.

To transform the system of linear integro-differential equations with partial derivatives and periodic coefficients, governing the joint bending oscillations of the main rotor blades and the main rotor hub on an elastic damping support, into the system of ordinary differential equations with periodic coefficients, Bubnov-Galerkin method was used. Transformation of the initial generalized coordinates governing each individual blade oscillations in rotating coordinate system into special generalized coordinates governing the joint oscillations of all rotor blades is demonstrated as well.

To analyze the computational results on forced vibrations being obtained, and collation with the experimental data on vibrations recording at the rotating parts of the hub, the motion pattern and vibratory processes character of the hub and blades, rotating in the rotating and non-rotating coordinate systems, are considered. The graphs, demonstrating the trajectory change of the point on the blade, and vibrational process character while transition from the rotating system to non-rotating one, are presented.

Computing of resonant diagrams and amplitude-frequency characteristics for MI-38 helicopter with six- and five-blade rotor with flexible plastic-composite blades. Comparative analysis of dynamic response of the “main rotor–support” system with various number of blades was performed together with corresponding amplitude-frequency characteristics plotting.

Based on the comparative analysis of the “main rotor–support” system dynamic performance for the two variants of the main rotor, and inference on the six-blade main rotor preference over the five-blade one was drawn for the MI-38 helicopter.

Piganov M. N., Shopin G. P., Nazarov A. A., Hovakimyan D. N. A Unit for Integrated Circuits Logic Gain Determining. Trudy MAI, 2019, no 108,

The article substantiated the necessity to account for logic gain of logic gates and integrated circuits. The authors suggest a new unit for the logic gain of microchips determining. The unit contains rectangular voltage generator, an integrated circuit being tested, a follower, loading elements, a switch, the AND gate, comparator, a pulse counter, a voltage reference source, univibrator, reversible pulse counter, decoder and indicator. The unit operates in both high and low level modes, and ensures high accuracy and validity of the logic gain determining.

Rectangular pulse generator, AND gate, pulse counter, voltage reference, and comparator are connected in the unit in series. The comparator output is connected to the second input of the AND gate. The input of the follower and signal input of the switch are connected to the output of the test circuit. The output of the follower is connected to the comparator second input. The univibrator input is connected to the comparator output. The output of the vibrator is connected to the subtracting input of the reversible pulse counter. The summing input of the reversible pulse counter is connected to the output of the AND gate. Each input of the decoder is connected to the reversible pulse counter output of the same name. Each decoder output is connected to indicator input. Each pulse counter output is connected to the cognominal input of the switch. Each of the outputs of the switch is connected to the cognominal load element 8-1 – 8-k, for each of which, starting from the second, the number of digital micro-schemes inputs, forming it and interconnected with each other, is two times higher, compared to the previous one. The unit allows determining the logic gain of the integrated circuit being tested by the high level changing (the first mode), and by the low level changing (the second mode) of its output signal.

Ensuring the second mode of the unit operation, allowing determine the logic gain of an integrated circuit being tested by the low level changing of its output signal, requires:

- Connecting the first input of the comparator to the follower output, and its second input connecting to the reference voltage source;

- To set the reference voltage source value to maximum allowable value of the the low-level voltage (logic zero) of output signal of integrated circuit being tested.

The suggested unit allows enhancing accuracy and validity of the integrated circuits logic gain determining. It is rather simple to operate.

Besides, the advantages of the unit compared to conventional ones consists in:

- the possibility to work with TTL, Schottky-TTL, and CMOS chips series;

- integrated circuits logic gain determining in two modes without changing the content of its blocks;

- ensuring automatic operating mode, and adaptability to changing microchips being tested and load elements 8-1 – 8k.

Tsvetkov V. A., Kondrat’eva S. G. Optimization of a broadband phased array with vibrator emitters. Trudy MAI, 2019, no 108,

The article studies the issue of matching antenna arrays (AA), consisting of vibrators and cross vibrators, located above the final metal screen at a height of ≈ λ/4. This matching is performed within the frequency range of ±10% and scanning angle of ± 60°.

Vibrators are powered by ideal oscillators with controlled impedance, located between the vibrator arms. At the first stage, a comparison of “blinding” properties in planar and linear AAs is performed. The results of comparison revealed that “blinding” manifested itself more strongly in flat AAs. At the second stage, the AA configuration is selected to mitigate “blinding” effect. Since “blinding” appears only in the E-plane, and depends on the distance between the vibrators, the best location option is to turn the emitters at an angle of 45° to the edges of the AA. In the third stage, the optimal emitter option is selected. Emitters with straight arms, sloping arms, and pins of sundry heights between these types of emitters are compared. The largest minimum width of the array pattern over the gain antenna pattern within the frequency range and radiation level along the screen, which should be no less than —10 dB. The best characteristics are demonstrated by the grid of vibrators with straight arms and pins of 0.225 λav for both vibrator and cross vibrator AAs.

At the last stage, the selected variant is optimized for the height above the screen, arm length and generator resistance. The gain level equal to 0 dB is selected as an optimization criterion. The direction pattern width at gain of 0 dB within the frequency range of ±10% was no less than 118.4° for vibratory AA, and 118.2° for cross-vibratory AA. Maximum SWR value within the frequency band in the scanning range of the vibratory AA was 3.3

The width of the beam along the 0 dB be realized gain in the frequency range of ± 10% was not less than 118.4° for the vibratory AR and 118.2° for the cross-vibratory AA. The maximum value of the SWR in the frequency band in the scanning range in the vibrator AA was 3.3. For the cross-vibratory AA, maximum SWR value was 3.3 as well.

Fomin A. I., Malyutina O. A. Efficiency index justification while information transmission radio systems design at the stage of scientific and research effort. Trudy MAI, 2019, no 108,

A mandatory item of the standard terms of reference for the implementation of scientific and research work (SRW) performing is the “Technical and economic requirements” item, which, in particular:

- establishes the limit value of the research cost;

- determins the stage at which technical and economic justification of the research continuation practicality is carried out;

- establishes the need to determine the estimated costs of implementing the results of research.

Each of items specified in the requirements is associated with evaluation of the technical complexity and efficiency of the designed information transmission radio systems (ITRS). Currently, the most common industry performance indicator of RW is a generalized indicator of the effect/cost. The research effectiveness justification is all the more necessary at the stage of determining the research contractor by the customer.

As a rule, the method of comparing some of the most important from the contractor’s view point characteristics of the designed ITRS with similar characteristics of a prototype is employed while technical effect assessing. With account for the dynamics of the characteristics being compared an inference is being drawn that the SRW performing will lead to the positive effect, and a new more efficient ITRS will be developed while the results of the experimental and development effort implementation. Besides certain voluntarism while the prototype selection and a set of compared characteristics, the drawback of this method consists in complexity of technical efficiency estimation, which may be explained by the necessity of vector indicator application, accounting for the values of individual characteristics.

The purpose of this article consists in developing a methodology for effect/cost calculating, based on the analysis of relative values of ITRS the main technical characteristics, formed by comparing these characteristics values with tmaximum potential values of the reference ITRS.

The relative indicator of technical efficiency, characterizing the effect of the R&D products being developed while the SRW performing, and economic efficiency indicator, characterizing increase of technical effectiveness per unit of the investment in the SRW under development, were suggested for estimating the effect/cost indicator widely used for SRW performing efficiency.

Rejection of subjective indicators of the preceding ITRS samples, which are being selected as prototypes at present, may be assigned to the advantages of the suggested indicator.

Talaev A. D., Borodin V. V., Petrakov A. M. Macromodel of LPWAN networks multiprotocol interaction. Trudy MAI, 2019, no 108,

Currently, there are more than a dozen different independent IOT protocols with radically different characteristics. Each Protocol is being developed and employed for specific the tasks. Combining a vast number networks into a single infrastructure based on different standards will significantly increase the versatility and adaptability of the system as a whole. The article is devoted to the issues of networking and development of a macromodel of Multi-protocol interaction.

Networking can be performed at various levels. The article analyzes the options for integrating at both applications and at the sensors levels. In the first case, interaction is performed through the appropriate network gateways, data from which comes to the Multiprotocol application server, which clients are end users. The Uni on-level network of sensors means that each sensor contains both hardware and software, enabling data exchanges in the different networks with the corresponding mono-protocol gateways. With to the considered variants of separate networks combining, two main methods of organizing Multiprotocol control systems are proposed.

To solve the problem of management based on a local network node in a Multiprotocol system, each node is equipped with software and hardware to analyze parameters of its operation, the state of the networks, and the environment. In this case, based on the parameters obtained, the node is able to independently sel ect the working network. Multiprotocol system in this case consists of nodes capable of working in several networks alternately

To implement a centralized management system, a management center Advisory module is added to the network, which is responsible for distributing nodes across networks and reconfiguring the network. The decision is made based on the information received from each of the terminal nodes about the state of the node, sensors and sensors working with it.

Leshko N. A., Petrochenkov D. M., Morgunov M. Y., Fedotov A. V. Coordinates determining mathod of scanning radio emission source in multi-position radar system with uncooperative illumination. Trudy MAI, 2019, no 108,

Multi-position passive methods for radio emission sources coordinates determining are widely employed in radiolocation. A number of literature sources suggest various methods for coordinates determining, which have already become conventional.

Some these methods require exact knowledge of the signals time and phase structure, while the other employ dynamic properties of the radiation source and additional special measurements of angular coordinates, i.e. bearing angles. For both cases, the corollary is the complexity of the equipment capable of realizing necessary measurements with the specified quality. Thus, developing methods for coordinates measurement of radio emission sources, allowing reduce the number of measurements is an important scientific and technical problem, requiring its solution. The problem of signals phase and time structure comparison in spaced-apart receiving points at a large a priori uncertainty due to the presence of the uncooperative illumination source is rather complicated while considering a multi-position radar system with uncooperative illumination source. It is necessary to regard the other properties of illumination sources. A scanning mode might be this property.

The article puts forward a method for calculating the scanning radio emission source coordinates, based on measuring the time intervals between successive irradiation of reception points of a multi-position radar system.

The coordinates calculation of the radiation source is achieved by the following:

- Measuring the scanning period of the source;

- Calculating the scanning source angular velocity;

- Measuring the time intervals between successive irradiation of reception point of a multi-position radar system;

- Calculating the distances to the radio emission source and azimuthal directions, using the base distance between the reception points of a multi-position radar system.

When organizing scanning of the space in a multi-position radar system based on a searchless spatial-multichannel survey method, the proposed time-based method for determining the distance to a scanning radio emission source allows reducing the uncertainty of the of the radio emission source location, improving thereby the accuracy of coordinates determining the of secondary radiation sources.

The main advantage of the proposed method for coordinates determining of the scanning radio source is the minimum number of measurements, the absence of measurable angular quantities, and independence of the reception points spatial orientation of a multi-position radar system relative to each other.

Starovoitov E. I., Yurchik I. A. Characteristics Optimization of an Aviation Synthetic Aperture Radar and Its Micro-Navigation System. Trudy MAI, 2019, no 108,

Falling of separable modules of launch vehicles occurs after space launches. Detected separable modules of launch vehicles are being evacuated from the impact area for further utilization. Search operations in a hard-to-reach terrain may take a good deal of time and require heavy spending. The authors suggest employing airborne synthetic aperture radar (SAR) for operational search and detection of separable modules of launch vehicles. This radar characteristics may differ from the analogs at hand.

An inertial micro-navigation system is employed to improve data quality being acquired by SAR. Currently, micro-navigation systems are employed in a great number of airborne SARs

Measuring error of the micro-navigation system is determined primarily by the the errors of its sensitive elements (accelerometers and gyros).

The types of sensitive elements applied in inertial units, and gyro errors correcting techniques of micro-navigation system, accumulated while long-term operation, are described. Analysis of requirements placed to micro-navigation system with inertial blocks based on laser gyros was performed.

For the assessment, it is assumed, that the aircraft-carrier flight is performed at an altitude of 9 km with a speed of 200 m/s. Characteristics of SAR, operating in Ku, X and C frequency bands, and sensitive elements of the units were determined for this initial data.

Based on Pareto sets, a technique for optimizing the inertial block mass (with account for the laser gyroscopes drift) of the micro-navigation system, and permissible error in the radial velocity measuring was developed. The same technique may be employed to optimize the inertial block size.

The results of this work may be used for developing airborne various purpose SARs.

Sokhranniy E. P. Methods for Solving Key Problematic Issues of Conflicts Resolution on Spacecraft Ground Control Systems Employing. Trudy MAI, 2019, no 108,

Specifics of spacecraft (SC) control by radio coverage zones and according to technological cycles of spacecraft control does not allow application of existing classical methods and techniques for planning ground spacecraft control means employing, which stipulates the necessity for original planning technologies developing.

Analysis of conventional planning of spacecraft ground control means application revealed that tha main planning problem consists in the necessity of conflicts resolution on the ground control means employing.

The main cause of conflict situations occurrence was determined as insufficiency of control means to realize requests from Mission Control Centers on communication session with space vehicles. The article presents the main conditions of conflicts occurrence, whereof the main is growth of the spacecraft orbital constellation. Analysis of conventional conflicts resolution process drawbacks, as well as possible aftermath of untimely or unsubstantiated decisions allowed formulate the basic problematic issues of conflicts resolution. They consist in operational efficiency increasing of decisions on conflicts resolution making and their validity.

The author suggests m ethods of problematic issues solving, consisting in

- automation of the decisions preparation process based on formalization of the said process,

- ensuring required values of confidence probability of expert evaluation on account of the expert panel of experts, consisting of no less than seven specialists, and expert evaluations concurrence (expert’s judgments expert panel opinions) with pre-arranged data for decision-making,

- processing firstly the top-priority requests;

- ensuring minimum damage from time shifting of conflicting requests realization.

The expected results of the suggestions implementation for problematic issues resolution are specified.

Borminsky S. A. A method for multilayer liquids density and viscosity integrated control in tanks based on ultrasonic sounding. Trudy MAI, 2019, no 108,

The article proposes an acoustic method for integrated control of multilayer liquids parameters, based on analysis of ultrasonic signal, propagating from the acoustic emitter upward the tank. The method is based on ultrasonic signal propagation upward the tank from the emitter through a multilayer medium. A line of acoustic receivers herewith is located above the emitter at a predetermined distance. In general, each acoustic receiver contains two channels. The first channel measures acoustic pressure using a piezoelectric transducer. In addition to the transducer, the second channel contains a buffer rod with fixed acoustic parameters, which allows determining the medium density. The fixed distance between the receivers allows determine the sound speed in the given layer. Thus, the media boundary height in the tank is determined by the propagation time. The liquid viscosity is determined by the attenuation. This method improves the accuracy and reliability of parameters measuring, as well as allows eliminate the need for an additional sound-collecting waveguide and reference reflectors, usually employed for high-precision measurements. The absence of the waveguide ensures a number of advantages. Firstly, with the line of receivers application the signal amplitude is much higher, than while employing reference reflectors, which significantly improves noise immunity and accuracy of the incoming acoustic signal front determining. Secondly, multiple signal re-reflections, hampering with the media boundaries positions determining, occur in waveguide measurements in the presence of additional reflectors. Acoustic receivers employed in the proposed method are small-sized and practically do not reflect signals, which allows determining even weakly stratified media. Thirdly, the waveguide presence impedes ensuring the same liquid stratification as in the tank itself especially while fuel drain/fill operation. While liquid adding to the tank, only the lower fraction enters the waveguide, which makes the layered media measurements inaccurate. Fourth, the waveguide absence allows employing practically any frequencies for measuring. The additional effects herewith peculiar to the waveguide sound proliferation do not arise. Structurally, the whole sensor consists of long studs, on which receivers and emitter are located. This design allows quick extraction of the sensor for precipitation removal and other maintenance operations.

The article considered various options of media location relative to acoustic receivers for measurements implementation, on which ground a signal-processing algorithm was developed. The following cases were considered: homogeneous medium with a medium level above the second receiver from the bottom; homogeneous medium with a level between the first and second receivers; several fractions, when each has more than two receivers; two fractions with media boundaries between the first / second and second / third receivers. This combination of the considered options allows obtain all the necessary cases while operation.

A prototype device was developed. With inexpensive components application it demonstrated the errors of combined measurements of level, density and viscosity of 0.1%, 5% and 12% correspondingly.

Romanov A. M., Gringoli F. ., Sikora A. . Wireless synchronization of onboard computing devices through WiFi. Trudy MAI, 2019, no 108,

This article deals with the problem of wireless synchronization between onboard computing devices of small-sized unmanned aerial vehicles (SUAV) equipped with integrated wireless chips (IWC). Accurate synchronization between several devices requires the precise timestamping of batches transmitting and receiving on each of them. The best precision is demonstrated by those solutions where timestamping is performed on the PHY level, right after modulation/demodulation of the batch. Nowadays, most of the currently produced IWC are Systems-on-a-Chip (SoC) that include both PHY and MAC, implemented with one or several processor cores application. SoC allows create more cost and energy efficient wireless devices. At the same time, it limits the developers direct access to the internal signals and significantly complicates precise timestamping for sent and received batches, required for mutual synchronization of industrial devices. Some modern IEEE 802.11 IWCs have inbuilt functions that use internal chip clock to register timestamps. However, high jitter of the interfaces between the external device and IWC degrades the comparison of the timestamps from the internal clock to those registered by external devices. To solve this problem, the article proposes a novel approach to the synchronization, based on the analysis of IWC receiver input potential. The benefit of this approach is that there is no need to demodulate and decode the received batches, thus allowing it implementation with low-cost IWCs. In this araticle, Cypress CYW43438 was taken as an example for designing hardware and software solutions for synchronization between two SUAV onboard computing devices, equipped with IWC. The results of the performed experimental studies reveal that mutual synchronization error of the proposed method does not exceed 10 μs.

Simonov A. S., Semenov A. S., Makagon D. V. Trends of high-speed communication networks development for multiprocessor computing systems. Trudy MAI, 2019, no 108,

The inter-nodal communication network is a key component for mass-parallel supercomputers. JSC “NICEVT” has developed the first generation of the Angara high performance communication network designed for application as a part of multiprocessor computational systems (MCS) of petaflop class, and ensuring high computer capacity scalability at real problems solving.

The following main trends can be distinguished in the MCS development:


  • connectivity enhancing,

  •   optical connections application,

  •   network adapter (NIC) and processor integration,

  •   MCS universalization to extend application on mass market by supporting the Ethernet protocol family.

The second generation of the MCS Angara with multidimensional torus topology, which development is scheduled for completion in 2019, is designed fro creating an MCS of subexaflopcic performance range. It is characterized by the modified Torus topology support, and much higher NIC characteristics, allowing plugging-in up to four processors at each node.

In the course of specification development of the second-generation Angara communication network, besides the operational parameters improvement, emphasis was placed on a significant functionality expansion, aimed at effective operation in both the high-performance MCSs segment and for data storage and Bulky Data processing systems.

These functional capabilities relate to SR IOV virtualization technology support, batches protection from the third-party tasks, non-guaranteed batches delivery for TCP/IP protocols stack realization, more effective routing algorithms for supporting the networks with “modified torus” topology, zonal adaptive routing and other features.

The MCS Angara third generation, which development is planned to be performed in 2021-2023, is focused on supercomputers creation of exaflops range, and is characterized by further improvement in NIC characteristics and optical connections application.

Algazin S. D., Solovyov G. H. On fast solution of the primal biharmonic problem. Trudy MAI, 2019, no 108,

At present, finite element method is the most widespread technique for solving the problems of deformable solid body mechanics. Its shortcomings are well-known and consist in the fact that while displacement approximation by a piecewise-linear function we obtain discontinuous tension. With that, it is worth mentioning that the majority of deformable solid body mechanics problems are described by the equations by the elliptic type equations, which result in smooth solutions. It seems relevant to develop algorithms, which would account for this smoothness. The idea of such algorithms belongs to K.I. Babenko. This idea was put forward by him in the early seventies of the last century. The long-term application of this technique for the elliptic tasks on eigenvalues proved its high efficiency. For example, the task on eigenvalues for the zero equation of Bessel was considered. With this, the first eigenvalue was defined with 22 signs accuracy after the decimal point on the mesh consisting of 22 nodes.

Unlike classical difference methods and finite-element method where dependence of the convergence speed on the number of mesh nodes is of power character, here we have an exponential decrease of error.

The first edition of the book by K.I. Babenko [22] contains the summary of fundamentals of the non-satiable numerical methods. It should be noted, that the studies in computational mathematics in this direction were not sufficiently popularized both in Russia and the world, and they are still practically unknown abroad.

Confirmation to this fact consists in the fact that nowadays an actual “rediscovery” (probably independent) of the same computational techniques started abroad under the name of “spectral” methods (S. Orszag, D. Gotlieb [4], E. Tadmor the USA). It is represented also by (h – p)-specializations of the finite element method (O. Widlund, the USA and S. Schwab, Switzerland), in which the power p of polynomials, employed for functions approximation within one finite element, increases simultaneously with the mesh refinement (i.e. at h → 0). Thus, we can only regret that the works by Babenko and his disciples appeared to be practically forgotten by now.

Vasil'kov Y. V., Timoshenko A. V., Sovetov V. A., Kirmel A. S. Functional characteristics assessment technique for radio-monitoring systems at restricted data on reliability parameters. Trudy MAI, 2019, no 108,

The article regard specifics of modelling and functional characteristics assessment of radio monitoring systems at restricted data on reliability parameters. It considers the issues of the systems mathematical models adequacy, including sundry approaches to the adequacy assessment. Approaches for earlier probability determination of hazardous event occurrence, which are based on trends extraction both in cases of noiseless assessments and in case of strongly noisy ones are presented. In the last case, the beginning, end and slope angle of the trends, which are employed while modelling radio-monitoring systems with random components, are extracted.

Specifics of failure flow intensity characteristics identification of the system elements while simulation organizing for analyzing failure flow intensity impact on the simulation results are considered, and recommendations are given for the cases, when the failure flow intensity is unknown in advance.

Specifics of mathematical simulation organization for the cases, when the failure flow intensity is unknown in advance, were considered, and analysis of the failure flow intensity effect on the simulation results was performed.

Jahidzadeh S. H. Issues of utilization optimization of extra photovoltaic panels for feeding unmanned aerial vehicles units. Trudy MAI, 2019, no 108,

At present, unmanned aerial vehicles (UAV) are widely employed for surveillance and information acquisition. One of the main problems of successful UAV functioning is providing them with power sources. Traditional solution of this problem consists in employing electric batteries and hydrocarbon fuel, which eventually leads to the UAV free flight duty period limiting. However, equipping UAV with solar batteries is non-traditional, but rather perspective solution. Solar batteries are unique type of power sources, which allow performing 24-hours flights, when energy stored in accumulators is employed while nighttime. It is noted that at present UAV energy supplying by solar batteries placing on the upper surface of the wings is a prospective solution to this problem. Numerous facts of this idea realization proved the effectiveness of solar batteries application for the UAV electric power supply. At the same time, solar energy employing for the UAV energy supplying is associated with a number of problems, which solution would help even more enhancement of their functioning effectiveness. One of these problems is the UAV supplying with extra solar batteries installed on the lower surface of the wings to utilize the diffusive solar energy. The purpose of the conducted studies consists in analysis of achieving higher efficiency of the extra solar batteries, installed on the lower surface of the wings. The article formulates and solves the problem of providing low altitude UAV with extra solar panels, realizing conversion of diffusive and reflected solar energy into electric energy. The author suggests enhancing the UAV components energy supplying by additional employing of dispersed reflected solar radiation. Theoretical basics of solar panels, installed on the lower surface of the wings, were analyzed. The issue on the most effective application of the extra solar panels installed on the lower surface of the wing was formulated. The article represents a variant of the problem solution of solar panels employing on the lower surface of the wings with maximum efficiency. According to the obtained results, the total extra radiation, which can be converted into electric energy, may be effectively utilized in case that the following condition would be met: with the Sun angle of altitude increase albedo should decrease and vice versa. This interrelation can be realized physically by special selection of space-time flight trajectory, meeting this requirement.

Hismatov I. F. Meteorological conditions reproduction technique while aircraft optoelectronic systems simulation. Trudy MAI, 2019, no 108,

The development objective of the technique considered in this article is fidelity increasing of the aircraft optical-electronic systems functioning simulation in the modes of ground-based object searching, auto-capturing and tracking due to the correct regard of meteorological conditions in calculations of brightness fields of target environment optical radiation.

At present moment, the problem of optical radiation transfer in the atmosphere is solved successfully, though techniques for its solution are still rather complicated, so that engineers would be able to employ them in practice of optoelectronic systems simulation. The article offers engineering approach to accounting for the atmosphere «optical state», based, however, on the simulation results with application of the proven optical models.

The technique suggested in the article is based on the application of interpolation methods for determining transparency and brightness of inclined paths in the atmosphere between the objects of sighting and recording instruments. A method for the atmosphere brightness and transparency computing on random paths according to tabular data containing these characteristics on ray the paths is proposed.

Application of the developed methodological apparatus allow reproducing while simulation conditions of OESTG functioning such as objects sightings against horizon in conditions of high air humidity or low values of meteorological sighting distance.

The methodological apparatus of the inclined paths brightness and transparency computing, presented in article, may be applied in software complexes for synthesizing images of the 3D scene of the aircraft optical-electronic systems target environment at the polygonal representation of its objects in mathematical models.

The developed methodological apparatus may be applied as well to create hardware-in-the-loop simulation of the aircraft optoelectronic systems, in which synthesized images are reproduced by collimator projection devices in the aircraft flight dynamics.

It should be noted, that the meteorological conditions replication technique, suggested by the author of the article, combined with the developed by the author 3-D model of brightness fields of the ground-based target guidance and technique for digital images synthesis form the simulation method basis for aircraft optical-electronic systems operation. Accounting for meteorological conditions impact on the atmosphere optical characteristics herewith enhances significantly the synthesized images fidelity, and, consequently, the optoelectronic systems quality indicators, obtained while their simulation.

In so doing accounting of meteorological conditions influence on atmosphere optical capabilities greatly increases validity of synthesize images and hence optical-electronic systems indicators of quality obtained by modeling them.

Ryazanov V. V. Spacecraft motion control while contactless space debris removal. Trudy MAI, 2019, no 107,

The urgency of the issue under consideration is determined by the need to develop methods for cleaning the near-Earth space from space debris objects that pose a threat to the spacecraft functioning. The article considered the process of removing the CubSat3U format nanosatellite from the near-Earth orbit by a contactless method employing an active spacecraft equipped with ion and control engines. A nanosatellite can serve as a universal base for conducting orbital experiments to develop the technology for removal using ion beam. When analyzing the removal process, it was assumed that at the stage of towing the distance between the active spacecraft and nanosatellite remains constant. For the stages of approach and towing, it is necessary to know the maximum value of control engines thrust, and the time of movement stabilization at which the nanosatellite center of mass will be located on the longitudinal axis of the blowing engine of the active spacecraft. The presented work is devoted to the analysis of the proposed control laws for the active spacecraft. The author obtained differential equations of the motion of an active spacecraft relative to a nanosatellite in the orbital coordinate system for the stages of approach and towing. The article suggest control laws of an active spacecraft relative to nanosatellite for the stages of approach and towing. Aerodynamic coefficients of the object being removed were used for determining the force transmitted from the ion beam to nanosatellite. With the selected coefficients of the control laws, the time of motion stabilization was determined.

Ulybyshev S. Y. . Trudy MAI, 2019, no 107,

This article is a continuation of the previous work, where the issues of substantiation and elaboration of the design appearance of a promising spacecraft towing vehicle (STV) with two variants of the propulsion system (DU) using liquid rocket engines (LRE) and stationary plasma engines (SPD) were considered, as well as the calculation of the power supply system of STV.

This paper describes in detail the features of the implementation of schemes for the space debris object (SDO) disposal by the STV, with the SPD remote control. The control laws of thrust vector orientation at the stages of flight to the SDO orbit with its subsequent removal, ensuring the problem solution, are selected. Mathematical modeling and comparison on the reachability area for two variants of the orbit of burial being formed, coplanar to the SDO orbit and synchronously precessing with it, were performed. In the first case, determining the scheme of one mission to the SDO orbit and the coplanar descent are hampered by the required orbit mismatch along the longitude of the ascending node (LAN) for the flight start and ensuring the possibility of operations repeating. In the second scheme, this aspect is eliminated by creation of synchronous precession orbits (SPO) during the flight by the inclination correcting. The limits of these schemes efficiency depending on the inclination and altitude of the SDO orbit were determined. Recommendations on the possibility of these flight schemes application depending on the orbits parameters of the towed objects are formulated.

Ledkov A. S., Sobolev R. G. Electro-dynamic tether system stabilization in a circular orbit. Trudy MAI, 2019, no 107,

The existence of technologies for strong materials production allows create extended space tether systems, which can be employed to solve a wide range of practical issues. Some projects imply the space tether system stabilization in a certain position. Stabilization can be realized by of the conductive cable interaction with the Earth electromagnetic field. The goal of the work consists in searching for the tether current control law, ensuring of the space tether system stabilization in a certain stationary state in a circular orbit. In contrast to the majority of existing works, the article considers the simultaneous stabilization of the system center of mass in a circular orbit and tether deflection angle stabilization in a certain stationary position.

A mathematical model of the cable system is described, and equations of motion using the second-kind Lagrange equations are obtained. In the framework of the assumptions made, the tether is considered as inelastic massless rod, and the bodies connected by it are material points. The model accounts for the attraction of the Earth and the Ampere force. A current in the electro-dynamic cable is considered as a control element. Control is sought as the sum of the programmed and stabilizing current force. It is shown that a limited set of program motions in a circular orbit can be implemented in the system. Equations of these motions are obtained. The stabilizing control is sought in the form of a linear dependence on generalized coordinates and velocities. The law of stabilizing control is sought in the form of a linear dependence on generalized coordinates and velocities. Selection of the control law parameters was performed using the Lyapunov theorem on asymptotic stability in the first approximation. Numerical simulation was executed to demonstrate the effectiveness of using an electrodynamic tether for the system stabilization in a circular orbit.

The results of the work may be employed while preparation of space programs involving of electro-dynamic tether systems implementation in a circular orbit.

Anan’ev A. V., Rybalko A. G., Goncharenko V. I., Klevcov R. P. Operational evaluation of target hit errors by free-falling containers of small-class unmanned aerial vehicles. Trudy MAI, 2019, no 107,

The article introduces a new approach to solving the problem of in-the-field operational determining of systematic error of drop-off a free-fall unguided container by prospective small-class strike unmanned aerial vehicles.

Analysis of the existing techniques of drop points’ coordinates determination of destruction weapons, employed for the manned aircraft, revealed their poor accuracy, which does not allow further performing the effectiveness evaluation of strike unmanned aerial vehicles application while ground targets striking.

Two ways of drop points coordinates determination of a free-fall unguided container were developed. They are based on modification of measuring and resection methods. The first technique realizes the direct measuring method, differing from the other by the sounding signal device application, particularly, a laser measuring device. The second technique is based on the indirect measurement method. Its difference from the resection method consists in the simplified order of measurements realization, and the application of one laser measuring device, instead of three.

The presented work reveals the content and the order of realization of each technique, which allows apply them not only for tests performing, but also while planned flights execution of unmanned aerial vehicles to maintain a high-level proficiency of operators at the ground control stations.

A scientific-methods apparatus for accuracy evaluation, based on comparing a polygon area as well as error theory methods, was developed for determining measuring error of the drop points coordinates of ammunition dummies performed by suggested and well-known methods.

Thus, two new operational techniques for drop points determining of ammunition dummies, being dropped from strike unmanned aerial vehicles, were developed. These techniques ensure two times and more increasing in performed measures accuracy. It will allow increase the efficiency of the systematic error determining for the batch small-class strike unmanned aerial vehicles in the field (combat) conditions.

Polyakov A. A., Zashchirinski S. A. Virtual space application for mock-design tests on a spacecraft electronic model. Trudy MAI, 2019, no 107,

A spacecraft creation in modern conditions makes the developer both conduct a profound engineering analysis in various fields and a large volume of tests in conditions close to the flight with the simulation of various impacting factors.

With the advent of advanced software for simulation modelling a concept of system-oriented design, based on application of the system of object-oriented models for developing basic simulation model of a space product, came to the forefront.

The described approaches allow performing tests, including model ones, with the help of which it is possible to determine with sufficient probability the spacecraft operational parameters and the reserve resource for each of them to make a decision on the readiness of the device for further application without flight design tests or with a significant cost reduction on them. Naturally, modelling, and simulation modelling in particular, herewith starts playing the main role, and its results evaluation with modern means of information processing. Already today, the modern means of modeling, engineering analysis and virtual design allow eliminate materiel application from mock-design, or at least significantly reduce the number of full-scale tests, substituting them by a greater amount of virtual tests.

At present, a technique for mock-tests executing by the spacecraft electron layout, employing virtual medium, is developed and conciliated at JSC “NPO Lavochkina”.

Virtual models application for tests preparation not only reduces the costs and risks associated with them, but also reduces the time required for the testing process itself.

It is obvious that the problem of experimental testing of the device can be fully solved only when it is completed by device tests, least of all differing from the standard sample, under the full-scale conditions, i.e. flight tests.

The presented article describes successively the goals and objectives imposed during the prototype tests in accordance with State Standards, as well as software and technical means to transfer the tests into the virtual space.

Babaitsev A. V., Burtsev A. Y., Rabinsky L. N., Solyaev Y. O. A technique for approximate stresses evaluation in a thick-wall composite axisymmetric structure. Trudy MAI, 2019, no 107,

Design calculations based on one-dimensional models of rods with variable cross-section can be effectively applied in the design of structures with large elongation. Similar one-dimensional models are employed, for example, for the design of columns, supports, rocket systems, etc. Such models allow, as a first approximation, evaluate the strength of a structure and determine loading conditions of its elements (compartments, sections) for further refined numerical calculations.

The article presents an option of the strength analysis performing method for a thick-walled axisymmetric structure consisting of a metal core (reinforcing component) and an external thick-walled shell of composite material. The structure is loaded with a linear load distributed along a part of its length associated with the acting external pressure and inertial forces associated with the resulting acceleration. The technique is based on a one-dimensional model of a composite rod with variable cross-section, approximately accounting for transverse deformations, which is necessary when analyzing a thick-walled structure operating under pressure. In the proposed approach, the geometry of the product is splitted into sections and approximated by fragments in the form of truncated cones and, in particular case, cylinders. As the result of the calculations, the distribution of the normal longitudinal tensile / compression stresses in the outer shell and in the reinforcing rod is being determined, and the tangential stresses at the boundary of their contact are being estimated. As the result of the test calculations, a reasonably good consistency of the proposed one-dimensional analytical calculation method with the numerical result obtained by refined finite element modeling for normal stresses acting in the rod and in the shell in the direction of the symmetry axis of the structure is shown. Numerical calculations were performed in the Comsol Multiphisics system using in a axisymmetric formulation. For tangential stresses at the contact boundary between the rod and the shell, approximate estimates, which quantitatively differ rather strongly from the numerical modeling, are obtained, and, therefore, require developing a refined technique accounting for the uneven normal and tangential stresses distribution in the radial direction.

Mitin A. Y., Tarlakovsky D. V., Fedotenkov G. V. Non-stationary contact of a cylindrical shell and perfectly rigid elliptic paraboloid. Trudy MAI, 2019, no 107,

The article studies a strain-stress state of a circular cylindrical shell of the Tymoshenko type and perfectly rigid cylindrical paraboloid in the process of their collision at the supersonic stage of interaction. The process of vertical impact is being considered, where the shell movement is regarded in Cartesian coordinate system. The contact occurs in free sliding conditions.

The problem setting includes equations of the shell motion, and equations of the elliptic paraboloid as a perfectly rigid body, boundary and initial conditions. To solve the problem, influence functions are used for a circular cylindrical shell, which represents normal displacement and is a solution to the initial-boundary problem of the impact on the surface of an elastic shell of normal pressure, given as a product of Dirac delta functions.

A numerical-analytical algorithm for solving the system associated with the inversion of Fourier-Laplace integral transformations, which is based on the bond of Fourier integral with decomposition into a Fourier series on a variable interval, was developed and implemented. Examples of computations are presented.

The goal of the work consists in formulating a spatial non-stationary contact problem for perfectly rigid impactors and a circular cylindrical shell of the Tymoshenko type.

The relevance of the research topic is stipulated in theoretical terms by the small number of studies of spatial non-stationary contact problems. From a practical viewpoint, it is associated with the need to determine the stress-strain state in the process of collision of an perfectly rigid body with a shell structure.

Stepanov R. P., Kusyumov A. N., Mikhailov S. A., Mikhailov S. A. Experimental study of wingtip vortices behind the finite-span wing. Trudy MAI, 2019, no 107,

The article presents the results of experimental study of wingtip vortices behind a rectangular wing of a finite-span in the near field (at a distance of 0.5 to 4.2 wing chords length from the trailing edge). A rectangular wing with a modified Göttingen 387 airfoil and aspect ratio of 7.8 was used in the experiments.

During the experiments, the Reynolds number corresponded to Re = 350000, and an incoming flow velocity was set to 28 m/s. Wing tip vortices were studied at various angles of attack in the range from —6° to +18°. Experiments were performed in T-1K wind tunnel of Kazan National Research Technical University named after A.N. Tupolev. The wingtip vortices study was performed by the velocity fields, obtained with PIV-system. Parameters identification of the vortex core was performed employing Cross-Sectional Lines method and Q-criterion, and demonstrated good agreement. The article presents dependencies of the core size changing on the angle of attack and a distance to the core section. It is shown that the vortex core size increases away from the wing the wing and the angle of attack increasing. The dependencies of the vortex core square on the Q value were plotted. It was established that the wingtip vortex bunch stranding at large angles of attack occurs at the shorter distances, than at the smaller angles of attack. The article demonstrates that maximum value of relative circulation is almost constant and independent from the angle of attack value.

Balakin S. V., Serbinov D. L. A method for liquid fuel rockets fueling level sensors parameters determining by the AC technique. Trudy MAI, 2019, no 107,

Methods for parameters determining of various objects based on the judgment on the measuring object according to its mathematical model and associated with analysis of alternating current passage through these objects gain more and more proliferation [1].

These methods found widespread occurrence in space rocket industry in particular. Abandonment of the CE5002 AC bridge, which was widely employed on technical complexes of space-rocket products, was the reason for new measuring techniques developing.

Dielectric liquids and cryogenic liquefied gases, reaching the temperatures about −253°C, are rocket fuel componentThe fueling level sensor represents a cylindrical air capacitor in double version in accordance with Fig. 1. Thus, the capacitive measuring method became widely spread in space-rocket products due to the possibility of operation in a boiling component, linearity of characteristic, movable parts absence etc. The fueling level sensor represents a cylindrical air capacitor in double version in accordance with Fig. 1.

A universal meter for impedance parameters' analyzer for performing studies in the field of materials analysis of ferroelectromagnetic phenomena, ion and superionic conductivity etc. [8] was developed at V. A. Trapeznikov Institute of Control Sciences of Russian Academy of Sciences.

The measuring devices for impedance measurements such as materials analysis, ferroelectricity, ionic and superionic conductivity etc. was developed in V. A. Trapeznikov Institute of Control Sciences of Russian Academy of Sciences.

In this transducer, computer controls measuring sequence and connects phase frequency detector (PFD) and analog to digital converter (ADC) firstly to the measuring object, and then to the reference with excitation voltage phase step of 

, where n is integer. As a result, after each measuring cycle the value Uij (i = 1, 2; j = 1 … n), representing projection of measured voltage vector on the reference voltage, is formed at the ADC output:

Where T is integration interval; Uij(t) is PFD input signal; Gj(t) reference signal.

Computer receives the codes carrying information on Uij(t), and computes real and imaginary part of the voltage at the tested object and measure.

The developed device allows measuring fueling level sensor parameters with high accuracy, but the main restriction while its application is the presence of a long double-wire cable communication link, reaching the length of 500 m. With such a cable link length, the phase measurements are extremely difficult to be realized due to the parasitic components of the communication line.

That is why the authors took another path aimed at developing a new technique for fueling level sensor parameters determining.

As long as the fueling level sensor (FLS) is a two elements two-pole, its parameters determining consists in alternating current impact at the two specified frequencies firstly on fueling level sensor, and then of the reference.

According to the given FLS equivalent circuit we have the following equations to determine its parameters:

where CW is working capacity of the sensor;

RL is leakage resistance of sensor;

RR is reference resistance;

ω1, ω2 is excitation frequencies;

  are measured currents via capacity sensor and reference at two frequencies.

However, operation results revealed that currents induced by the communication line length fr om the external sources, as well as AC frequencies difference value affect measuring results, namely, the more the AC frequencies separated, the higher the measuring accuracy.

Thus, the goal of the new measuring approach is increasing measuring accuracy due to bias currents compensation and providing one measurement at the direct current excitation using the following equations:

wh ere sign of Δ denotes bias currents compensation, which were measured at turned-off AC and DC current sources.

The Xilinx FPGAs were employed for the newly developed technique realization, on which base measuring data processing and computation blocks, and functional blocks of analog measuring channel, including analog-to-digital converter of integrating type, sine voltage generator, frequency and scale of amplification control circuit.

The developed measuring technique allowed create a unit for ensuring FLS parameters measuring on the technical complex instead of out of production CE5002 AC bridge.

The technique described in the article may be applied for parameters measuring of two-poles, employed as physical processes sensors (temperature, pressure, level of liquid and granular media, etc.) at the industrial objects, transportation means and, above all, in the systems for measuring fueling level of liquid fuelled rocket carriers in the space-rocketry.

Golomazov A. V., Smirnov N. Y., Iosifov P. A. Creating a concept of information support for decision-making based on man-machine interaction procedures. Trudy MAI, 2019, no 107,

At present, studies on the information support formation for decision-making in the environment of multi-agent systems can be referred to as particularly relevant, since a multitude of problems to be solved can be represented as functional agents of multi-agent systems. Such studies integrate both the results of solving deterministic problems and the problems solved based of the theory of fuzzy sets.

This scientific article reflects theoretical aspects of the interaction between the Cargo Owners and Carriers, and information support formation for decision-making in the multi-agent platform environment. At the same time, methods for solving the tasks based on a deterministic and fuzzy approach are proposed at reaching a consensus of interacting subjects. The article explores the possibility of applying the dialogue interaction principles of interacting subjects based on the multi-agent system (MAS) software in conditions of uncertainty, risk and conflict.

The considered approach of interaction between the Cargo Owners and Carriers is based on the following main provisions that ensure [6]:


  • realization of one of the principles of the consciousness functioning, i.e. providing the decision-making processes participants with a common interpreter of information on the processes monitored and the state of implementation of transport and logistics process (TLP);

  • ­ mutually beneficial combination of human capabilities and means of MAS in information processing;

  • ­ joint implementation of the functions of information services, regulated interaction of all participants in the processes of the formation of decision support system (DSS).

Personnel is presented with the opportunity to form requests for the selection and extraction of information available in the system. These queries describe combinations of features using the functions “equal”, “not equal”, “greater”, “less”, “greater and equal”, “less and equal”, “nesting” or special functions for which information will be selected, and those information components are determined that should be extracted from the selected array and provided to the specified persons. Requests can be formed for both interconnected and unrelated fuzzy information.

In this mode, on the request of personnel from among the subjects, the generated request can be cataloged in the MAC environment and used multiple times with the possibility of correction before the next execution.

The set of forms for displaying the information received as the result of a request processing can be diverse enough (text, statistical data, graphs, charts, etc.), and it depends on the specific ways of using information on the activity being monitored, allowing the interacting swarm subjects of Cargo Owners and Carriers advance to a consensus more intensively and expeditiously.

Gerasimchuk V. V. Dynamics modelling of the landing platform two-link mechanism. Trudy MAI, 2019, no 107,

The article is devoted to the dynamics study of the two-link mechanism of the landing platform of the landing module. Federal space program includes the planet rover delivery on the planets under exploration by landing modules. An important scientific problem on rational selection of design solution for studying the deployment dynamics of the multilink mechanism of the landing platform gangway is formulated.

The author analyzes the existing methods of compiling the multi-link mechanisms motion dynamic equations, and chooses the of Denavit-Hartenberg matrix representation together with the Lagrange-Euler method for complete description of the mechanism motion. The movement dynamics is represented as a two-link mechanism with rotational joints. Further, we formulate a direct problem of kinematics to determine the vector of generalized accelerations for a given force and moments. A system of nonlinear differential equations of motion is being derived, which is numerically integrated, and modeled in the EULER software complex. The EULER software package was developed by NPO Avtomatika and meant for mathematical modeling of multi-component mechanical systems dynamics. The results are compared, and conclusion is made on the sufficient convergence of the results (the discrepancy does not exceed 15%).

The author draws attention to the fact that nonlinearity generates heterogeneity of dynamic, elastic and velocity properties of the mechanism and the variability of parameters in nonlinear equations. This feature is clearly manifested in the positions of the multiplicity π of the generalized coordinates and at their zero values. When φ1 = φ2 = 0, the mechanism is pulled into a line, or if φ multiples of π and the links are folded, a loss of controllability may occur. The author explains this by the fact that the choice of the conceptual model of the mechanism and the formation of its kinematic design model is an independent task.

Approbation of the developed system of non-linear equations with the results of the work on the transformable structures of the EXOMARS SPACECRAFT landing platform was performed additionally. A conclusion was made on the model suitability at the outline design and determining the layout and main kinematic characteristics of the mechanism of the landing platform gangway of the landing module of the interplanetary space station.

Yudin D. A. Numerical modelling results of the products structures upon the impact when hitting liquid and solid impediments. Trudy MAI, 2019, no 107,

The article presents an adaptive theory and the results of mathematical modeling of structural elements of products while encountering with various types of obstacles. The problem of developing an effective method for the numerical simulation of three-dimensional dynamic problems of hydroelasticity and structural dynamics is being solved. Finite element method is used to solve these coupled problems.

The results of the stress-strain state calculations using numerical simulation, as well as some highlights of the process of impact interaction of the product and obstacles are obtained.

In recent years, a large number of analytical and semi-empirical methods have been developed to study the stress-strain state of structures under impact. However, these methods were used mainly for a limited type of structures, as a rule, of simple geometry and in the presence of a number of restrictions in the problems formulation and boundary conditions formation. At the same time, it is obvious that in order to solve practical problems along with those of the objects of the rocket and space industry, it is necessary to account for rather complex geometry of structural elements and the corresponding boundary conditions. The main modeling problem in this case is the need to obtain a joint coordinated solution of the equations of structural dynamics and the equations of flow of liquid or solid barrier. In this regard, numerical modeling is considered to be one of the main and non-alternative approaches these days for solving these complex problems.

The advantages of the FEM are as follows: relatively simple setting of boundary conditions, sufficiently high accuracy, and the capability of tracing the entire evolution of the free boundary as well as a high degree of universality. It is worth noting that this method application while performing calculations in the areas with complex free surface behavior can lead to the cell grid boundaries overlapping due to large deformations of the simulated structure.

The goal of the work consists in developing an effective methodology for numerical modeling of three-dimensional dynamic problems of hydroelasticity for specifying the stress-strain state of elements of metal structures impact upon water and a solid impediment impact.

Goldovsky A. A. Numerical models for contact zones prediction as the result of impact interaction of aviation structures with barrier in emergencies. Trudy MAI, 2019, no 107,

This presented article is devoted to the study of issue on the possibility of predicting and determining the contact zones of the colliding elements according to the result of their impact interaction. Developing methods for predicting contact zones is an urgent task in the case of any objective data absence on real cause-and-effect relationship, led to the impact interaction, and subsequently to some abnormal situation (emergency). Frequently, the study of an emergency often comes down to many experimental works, in which the opportunity of repeating all the conditions of an abnormal situation (emergency) that has already happened is not always possible. The presented article suggests a method, which may significantly reduce the number of experimental studies of abnormal situations (emergencies) in combination with the numerical simulation. The general application area of the developed models is aerospace industry and mechanical engineering.

The subject of the study is the impact interaction of two elastoplastic bodies. Due to the shock interaction, the stress-strain state of an elastoplastic barrier is considered to obtain a qualitative assessment of the force factors acting on the colliding elements. The article presents the main methods for studying impact interaction, as well as numerical simulation of the impact of two elastoplastic bodies.

Based on the conducted numerical simulation, methods for determining contact zones of impact interaction are presented; an algorithm for recovering the picture of impact interaction is developed; the main drawbacks of the method are considered; ways of development in terms of describing more complex geometric bodies and sequential-circular motion are proposed.

Kovalev N. V., Baikov A. E. On sticking zone of a box with internal oscillator on a horizontal plane. Trudy MAI, 2019, no 107,

Problems of the theory of mechanical systems with dry friction are popular at present among researches and find many applications while studying, for example, motion of mechanisms consisting of a solid body and moving masses in it. Discontinuity of the right hand sides of the equations of motion creates many problems while studying, and classical theory of differential equations does not work for the equations of movement with dry friction.

The first paragraph of the article considers very simple and popular model of the system with dry friction, i.e. a box clenched by springs on the conveyor belt. A dry friction force, subordinate to the Amonton’s-Coulomb law, acted between the box and the belt. A sticking zone was plotted, and periodic movements and limit cycle of the box on the conveyor belt were obtained.

The article regards translational movement of a box with internal oscillator along the horizontal plane. An Amonton’s-Coulomb dry force acted between the box and the plane. Equations of movement of the box with internal oscillator were obtained it the second paragraph of the article. These equations concede general solution in every domain of continuity. The slipping zone conditions when the static friction forces act on the box were obtained.

The third paragraph of the article validates mathematical correctness of the model under consideration. This correctness is based on the concept of Philipov’s solution of the ODE system with discontinuity of the right hand sides. The model determinateness follows out from Filipov’s theorem on existence and uniqueness-in-the-future solution of Cauchy problem.

The final motions of the system are studied in the last paragraph. The box always falls into the sticking zone after several iterations.

Tokarev V. V., Deniskina A. R. Vendors’ Maturity Assessment Processes Modelling and Automation Based of the Best International Practices. Trudy MAI, 2019, no 107,

The article considers the issues of modeling and automation of processes and tools for assessing vendors’ maturity based on the best international practices, contributing to possible risks identification at the early stages of contractual relations, their prevention and elimination.

The data on existing both domestic and foreign techniques for vendors’ assessment was systematized. Analysis of the main causes of default on contract commitments by the nuclear industry vendors was performed. Exigencies and expectations of the sectorial quality services, as well as external customers’ requirements were formalized. The article analyses the results of the discrepancies, revealed by the customers while pre-contract and inspection audits, as well as corresponding sectorial legislative, regulatory and other requirements and recommendations. The most important trends for the vendors’ maturity assessment. Based on studying and analysis of the best world practices, a technique for works applicability signs assignment, necessary for meeting the customer’s requirements. As the result, a customer acquired the possibility to draw up a checklist for its specific requirements.

To unify the checklists configuration variants, work types classifier was introduced for manufacturers and contractor/servicing enterprises.

Data analysis results on the existing object revealed that the presence of explanations, describing the mechanism for compliance with the requirements assessment eliminates a possible judgment subjectivity and a risk of cassation from the side of the enterprises under the audit.

The authors developed a checklist form, which should contain a set of the following signs, ensuring the possibilities of its configuring according to the customer’s requirements, introducing the audit evidence and objective calculation of the vendor maturity level (the total score). It should contain also the requirement description, its clarification, systemness, and applicability for the type of work; assessment of the compliance with the requirement; assessment substantiation (records of the audit evidence); the auditee surname, name and patronymic, the date of the assessment performing.

The developed vendors’ maturity model accounts for the difference of the errors elimination costs, occurred at various stages of product manufacturing life cycle.

Grushenkova E. D., Mogilevich L. I., Popov V. S., Popova A. A. Longitudinal and bending oscillations of a three-layered plate with compressible filler contacting with a viscous liquid layer. Trudy MAI, 2019, no 106,

The study of a three-layered plate interaction with a layer of pulsating viscous incompressible liquid was performed. The liquid layer motion was regarded as a laminar one occurring in a narrow channel with parallel walls. Sticking conditions at the boundaries of liquid contact with the channel walls were assumed. The upper wall of the channel is being regarded absolutely rigid. The lower wall of the channel represents three-layered plate, and its bearing layers satisfy Kirchhoff's hypotheses. The plate filler is being regarded compressible in the transverse direction. The free support conditions are accepted at the plate end-faces. Oscillations of the three-layered plate are caused by the pressure pulsations at the channel end-faces. Pressure in the liquid layer changes herewith according to harmonic law.

The plane problem of longitudinal and bending hydroelastic oscillations of the three-layered plate was studied. The elastic displacements amplitudes of the three-layer plate were supposed to be much smaller than the thickness of the liquid layer in the channel. On the other hand, the longitudinal size of the channel was supposed to be much bigger compared to its transverse size. The hydroelastic problem consists of dynamics equations of the three-layered plate with compressible filler and liquid dynamics ones. The hydroelasticity problem was formulated. It consists of dynamic equations of the three-layered plate with compressible filler, as well as viscous liquid layer dynamic equations, namely Navier-Stokes and continuity equations. Accounting of normal and shear stresses, acting from the liquid side on the plate bearing layer contacting with it, is being performed while the experiment. Linearization of hydrodynamic equations was performed by the perturbation technique, and solution of the above said problem was obtained for the case of steady-state harmonic oscillations. Hydrodynamic parameters of the liquid layer were determined. Frequency dependent distribution functions of elastic displacements of the plate's layers and pressure of the viscous liquid layer were plotted.

Dudarkov Y. I., Levchenko E. A., Limonin M. V., Shevchenko A. V. Computational studies of some types of operational and technological damages impact on bearing capacity of stringer panels made of composite fiber reinforced plastic. Trudy MAI, 2019, no 106,

At present, one of the main tendencies while aircraft design is carbon fiber reinforced plastics implementation in the load carrying structure of the airframe. Composites allow the structure weight reduction and the aircraft performance improvement. There are examples of composite materials successful implementation in the wing structure, stabilizer, fuselage and other aircraft structural elements in civil aviation.

A serious problem on the way of effective implementation of modern polymer composite materials in the aircraft airframe load-bearing structures is their high sensitivity to in-service damages and technological defects. The issues of strength characteristics degrading in the presence of damages and defects are generally being solved on the experimental basis. Nevertheless, computational methods allow performing similar estimations.

The article presents the results of numerical studies on operational and technological damages effect on strength and stability characteristics of a stringer panel. Impact damages of skin, stringer delamination, and the stringer peeling fr om the skin were regarded as damages. The effect of the above said damages' sizes on the strength and stability characteristics of the panel was being studied. The studies were performed by the finite elements method, including its nonlinear version.

The article demonstrates the presence of the critical damage size of the skin. Prior this size the requirements to residual strength can be met. This lim it exceeding leads to irreversible process of composite destruction and exhaustion of the panel bearing capacity. Numerical studies of the panel bearing capacity with damage in the stringer allowed determining the minimum value of the panel residual strength at the damage zone size increasing. The obtained results may be handy for the composite structure residual strength estimating and forming damage criteria with regard for possible in-service and technological damages.

Ivanychev D. A. Solving thermoelasticity problems for anisotropic solids of revolution. Trudy MAI, 2019, no 106,

The goal of the work consists in determining the stress-strain state of anisotropic bodies of revolution in conditions of temperature exposure with no internal heat sources. The body boundary is free fr om external forces and kinematic dependencies.

The task setting is ensured by the inverse method development for the class of stationary axisymmetric thermoelasticity problems for transversely isotropic bodies. The author proposes the theory of the internal states’ spaces basis forming, including displacements, deformations, stresses and temperature. First, a basis of plane auxiliary states is formed for the case of plane deformation, based on the general solution of the plane thermoelasticity problem for a transversely isotropic body. Further, on its ground, a basis of internal spatial states is being induced by integral overlays method. This basis is being orthonormalized based on the Gram-Schmidt recursive-matrix orthogonalization algorithm, where integrals of the product of temperatures act as cross scalar products. After the basis orthogonalization the target state is being determined by the Fourier series, wh ere the coefficients represent definite integrals which kernels compose the functions of the temperatures in the basic elements multiplication by the specified temperature.

Verification of the solution is performed by comparing the specified temperature field with that obtained while the solving.

A strict solution of the test problem for a circular cylinder, and an approximate solution for a body in the form of a stepped cylinder, made of rock, with the corresponding conclusions on the series convergence are presented. A graphical visualization of the results is presented as well. The advantage of the presented approach consists in the fact that the most time-consuming calculations, namely an orthonormal basis construction, are performed once for a body of a certain configuration. Subsequently, this basis can be used for solving various thermoelastic problems for this body.

Khatuntseva O. N. Analytical method for velocity profile determining of the turbulent liquid flow in the flat Poiseuille problem. Trudy MAI, 2019, no 106,

The present paper continues the circle of publications devoted to solving the hydrodynamic problems allowing an analytical approach to their consideration. Searching for analytical solutions in rather simple «model» problems is not an end in itself. Developing an approach, enabling accounting for the laminar and turbulent flow modes specifics in Navier-Stokes equations (NSE), for further correct NSE integrating by both analytical and numerical methods is the main motivation of this work. However, studying specifics of various flow modes is possible namely while solving the problems allowing exact (analytical) solutions. Unfortunately, due to their complexity the Navier-Stokes equation have such solutions for a very restricted set of problems, namely for very simple geometries. The most well-known of them all are:

– The Hagen-Poiseuille problem, describing the flow of the incompressible thermally non-conductive liquid in a tube of a circular cross-section;

– The flat Couette problem describing the flow of incompressible thermally non-conductive fluid between two infinite parallel plates, moving under a constant velocities in opposite to each other directions in their own planes;

– The flat Poiseuille problem describing the flow of incompressible thermally non-conductive fluid under the pressure drop between two infinite parallel plates.

There is unique analytic solution describing the laminar profile of velocity for any Reynolds numbers in all these problems while Navier-Stokes equations integration under the absence of entropy production caused by excitation of velocity stochastic pulsations.

Two solutions were determined analytically due to the account of the entropy production in NSE for both the flat Poiseuille problem and other above-listed problems (considered in the previous articles). One solution corresponds to the laminar flow mode, and the second to the turbulent one. The first one is realized for any Reynolds numbers and is specified by the parabolic velocity profile in the total fluid flow domain, and the second one is realized for relatively high Reynolds numbers and is specified by the logarithmic velocity profile in the center of the flat channel. The multiplier prior to the logarithm function is the von Karman constant. The article presents comparison of the results with the available experimental data.

Ermakov V. Y. The use of the magnetic-liquid effect to reduce static and dynamic imbalance from the moving masses of drive devices. Trudy MAI, 2019, no 106,

While mechanical systems with rotating or moving masses operation, small amplitude vibrations, which cause negative effect on both control system (CS) operation and sensing elements, are being transferred to the spacecraft structure, which may lead to the CS orientation accuracy degradation. This problem can be solved provided that mounting locations of both precision instruments (PI) and moving masses are known. It is required to determine the moments of inertia of the spacecraft elastic structures provided that dynamic requirements depending on the spacecraft angular velocity are fulfilled, and minimize:

- micro vibrations while special spacecraft precision instruments operation;

- functions of static and dynamic imbalance.

A five-degree-of-freedom vibration isolator employing magneto-liquid effect was developed to reduce the effect of the above said factor on the relative movement of the optical path. The experimental results of its mathematical modelling are presented as well. The tests on studying the effect of the cavity height between the permanent magnet enveloped by the magnet liquid and the unit case, as well as the permanent magnet and case materials on the system characteristics; the permanent magnet base area on the system operation effectiveness were conducted. The results of experimental studies of the vibration system with vibration isolator employing magnet liquid effect revealed 5–10 times reduction of absolute linear traversing. The suggested system herewith was recommended for “Spectrum-UV” spacecraft adaptation as a tool for eliminating undesirable micro disturbances created by flywheel-motors.

Zvonarev V. V., Moroz A. V., Sherstuk A. V. Evaluation technique of direction pattern characteristics of an ultrasonic radar in the antenna aperture synthesizing mode. Trudy MAI, 2019, no 106,

The purpose of the article consists in direction pattern characteristics verification of ultrasonic radar in the antenna aperture synthesizing mode, which were obtained both by experiments and calculations.

The object of this article is ultrasonic radar in the antenna aperture synthesizing mode.

The subject of the article is the transmitting ultrasonic sensor functioning.

The methodology of writing the article is comparing the results obtained employing a mathematic model of the radar system in ultrasonic wavelength range and by experiments with its real prototype.

Developing the radar with synthesized antenna aperture assumes:

–  functioning processes modeling of elements of the pattern under development to obtain the direction pattern characteristics;

–  designing and developing the prototypes realizing the main operation modes of the pattern or its constituent parts.

The authors proposed to develop a prototype in ultrasonic range rather than in radio range, which allowed modelling the main processes with real equipment employing high accuracy and reliability. Modelling of the unit’s elements functioning processes is being performed to obtain the values of direction pattern characteristics. The obtained values evaluation is being performed with the technique for evaluating the direction pattern of the ultrasonic radar in the antenna aperture synthesizing mode.

The article regards the issues of direction pattern parameters modelling, as well as presents the evaluation results of characteristics of the direction pattern of the ultrasonic transmitting device, obtained applying the suggested methodological approach. Experimental validation of the results applying ultrasonic test site was performed.

Application of the presented technique allows refine errors evaluation model of a radar-location channel of the radar prototype with the synthesized antenna aperture, and solve problems of radiometric calibration of the system through path prior to its manufacturing.

The developed technique is practical to employ while developing algorithms for controlling direction pattern of prospective radars with synthesized aperture already at the stage of laboratory workout.

Generalov A. G., Gadzhiev E. V., Salikhov M. R. Spiral antennas application for prospective onboard systems and complexes. Trudy MAI, 2019, no 106,

The onboard antenna-feeder devices constitute an integral part of space vehicles according to both the type used (small or large) and the target-oriented task: Earth remote sensing; weather observation; emergencies monitoring; communications; scientific research; applied research and etc.

Each of the above said tasks solving is accompanied by a certain set of onboard equipment application.

However, there are onboard radio links, such as inter-satellite communication, navigation system, telemetry etc.), which include receiving and transmitting antennas.

The article presents the spiral antennas application for prospective onboard systems and complexes of transportation vehicles.

For example, application of a quadruple single-turn antenna (with operating frequency of 406 MHz) with circular polarization of the clockwise rotation was proposed as a receiving antennae, while a quadruple spiral antennae (with operating frequency of 1544 MHz) with circular polarization of the counterclockwise rotation was proposed as a transmitting one. The emitter and recording device of the transmitting antenna are fabricated by printing technology. Both spiral antennas are employed as a part of the antenna system of the COSPAS–SARSAT onboard equipment.

The COSPAS-SARSAT system includes two types of space vehicles:

- of a low Earth orbit;

- of a geostationary orbit.

The article presents also the spiral antennas developed for various onboard systems and complexes such as telecommand system, satellite navigation, inter-satellite communication, scientific system, etc., for the spacecraft such as “Meteor”, “Ionosphere”, etc.

Mikhalyev S. M. Aerospace System Adaptation to Satellite Injection into High-Energy Orbits. Trudy MAI, 2019, no 106,

The object of the study is a reusable aerospace transportation system based on a twin-fuselage subsonic carrier aircraft for launching various payloads into near-Earth orbit.

The purpose of the work consists in determining the applicability of reusable aerospace systems for injecting payloads into high-energy orbits including interests GLONASS.

The method and methodology of the works handling are based on theoretical and computational works, including application of Computer-Aided Design and Computational Fluid Dynamics.

The work presents the follwing:

– analysis of the main GLONASS parameters as the initial data for the aerospace system configuration design;

– trajectory formation of the reusable aerospace system with its return to the launch point of its first stages;

– comparative analysis of various types of the space-rocket system fuel;

– aerospace system basic parameters optimization for GLONASS satellites delivery into orbit.

The article analyses application of partially reusable aerospace system, i.e. maximally unified modification of the fully reusable aerospace system, for satellites injection into high-energy orbits.

To increase the rocket system energy performance required for delivering GLONASS satellites to the high-energy orbits, the authors proposed an aerospace option with the non-recoverable second rocket stage and a space accelerating block on oxygen-hydrogen fuel (like the two first stages of the aerospace system). The performed analysis of appearance formation allowed determining optimal trajectories and thrust-to-weight ratio of the aerospace system and the space acceleration block.

Karpuhin E. О., Makarenkov N. S. Application of frequency-hopping OCDM-OFDM signals for physical level attacks preventing. Trudy MAI, 2019, no 106,

It is utterly important to ensure the intentional radio jamming resistance for information and communication systems of special and military purpose. Attacks on such kind of networks may inflict vast damage, including a State level. Simulated jamming exercises the most dangerous impact among the existing intentional interferences, since they repeat the signal structure while its transmission. The impact of such kind of interferences may also disrupt the information availability while attempting to get access to it through a radio channel.

The presented work proposes application of frequency-hopping OCDM-OFDM signals to counteract the physical level attacks of OSI model and enhancing the signal structural stealth. Jamming immunity from the relay interference, indicators of structural stealth, and the impact from Doppler effect were considered. Simulation revealed the energy gain of 1 dB while employing the suggested signal-code structure prior to frequency hopping OFDM signals in conditions of relay interference. It demonstrated also that the signals of this type possess higher structural stealth figures, as well as more stable to Doppler effect compared to OFDM-frequency hopping signals.

The disadvantages of the proposed approach include the complexity increase of the signal-conditioning and synchronization systems on both the receiver and transmitter. It is necessary to ensure assignment of code signature from the earlier generated OCDM to each each subcarrier of the OFDM signal while the signal forming process. Besides, the frequency-hopping spread spectrum process is rather complicated itself. It requires fine synchronization between the receiver and transmitter, as well as knowing the pseudo-random sequence. The suggested signals will be less effective while data transmission in the channel without attacker, than the structure with FH-OFDM application.

Masalkin A. A., Kolesnik A. V., Protsenko P. A. A technique for application planning of satellite radio-monitoring system means. Trudy MAI, 2019, no 106,

The presented work puts forward an approach to raise the effectiveness of the satellite radio monitoring system means application. The subject for studies is methods for the said system planning.

The existing methods of solving the problem of planning the satellite radio monitoring system means involvement are based on employing a flexible approach, foreseeing larger encompassing of the territories with high population density, and a smaller one for the territories with small population density. This approach has a number of disadvantages including inability for regarding the density of space vehicles location on a geostationary orbit, and impossibility of simultaneous transponders radio monitoring of one spacecraft accounting by several radio monitoring means.

To eliminate the above said disadvantages the authors suggest a technique for application planning of the satellite radio monitoring system means regarded in this article, and based on solving the problem of discrete programming. The quality indicator is effectiveness, i.e. the number of serviced channels. The problem is aggravated by the fact that the objective function is non-linear, which makes impossible application of mathematical programming methods. For this complexity resolve, a linearization technique for the function with Boolean parameters based on additional variables introduction is put forward.

This technique essence consists in performing an iteration procedure for solving the problem of discrete programming with subsequent refinement of the objective function value.

Computational experiments were conducted employing suggested technique for radio monitoring means planning. The obtained results prove the principal possibility of increasing the satellite radio monitoring system effectiveness by 15-30% due to channels duplication elimination.

Podstrigaev A. S., Slobodyan M. G., Mozhaeva E. I. Criteria set for efficiency evaluation of counteraction to unmanned aerial vehicles methods. Trudy MAI, 2019, no 106,

The presented work puts forward a technique for qualitative comparison of technical means for counteracting the growing unlawful application of unmanned flying vehicles (UAV). This technique is based on a set of criteria for the effectiveness evaluation of UAVs counteraction techniques developed by the authors.

The article itemizes the most widespread technical methods for the UAV counteraction. It states the main disadvantages of the conventional approaches to these methods evaluation, such as evaluation incompleteness, poor analysis of application conditions, and in many cases the lack of quantitative indicators.

reveals the most commonly used techniques of counteraction methods and the basic disadvantages of approaches to efficiency evaluation of these counteraction methods. They are an incomplete evaluation, weak analysis of practical implementation conditions and, in most cases, quantification deficiency. It is demonstrated, that physical principles difference of counteraction methods realization causes a problem of their direct comparison. Thus, the goal of the presented work consists in developing the system of criteria for qualitative evaluation of the UAV counteraction methods devoid of the said disadvantages.

The presented set of criteria allows performing a comparative evaluation of various UAV counteraction methods with regard for their characteristics of detection and counteraction, the UAV recognition quality, hardware volume, versatility and consequences of its implementation, electromagnetic compatibility, economic indicators etc. The proposed system envisages criteria splitting into sub-criteria, as well as partitioning the latter into their own sub-criteria and further by analogy if necessary. The final quantitative evaluation is computed by the special equation employing the obtained evaluating coefficients depending on the introduced weight coefficients of each criterion and sub-criterion.

The developed set of criteria allows quantifying various implementations of the existing UAVs counteraction methods; compare various implementations of one or several methods of UAVs counteraction; educe more effective counteraction methods for specific application conditions; forecast the efficiency of prospective counteraction methods.

Kosachev I. M., Chugai K. N., Rybackov K. A. Methodology of high-precision non-linear filtering of random processes in fixed structure stochastic dynamic systems (Part 2). Trudy MAI, 2019, no 106,

The article presents a methodical approach to high-precision nonlinear filtering of multidimensional non-Gaussian random processes in continuous-time stochastic dynamical systems with a fixed structure. The high accuracy of the developed algorithms for the optimal nonlinear filtering problem is stipulated by application of a posteriori higher order central moments of the filtered process. Adaptability of the developed high-precision nonlinear filtering algorithms is ensured by real time computing of a posteriori skewness and excess kurtosis for all phase coordinates of the filtered process, their subsequent comparison with the threshold values corresponding to Gaussian random process. If necessary, a posteriori higher central moments of the process being filtered are used in filtering algorithms.

The methodical approach under consideration to high-precision nonlinear filtering of multidimensional non-Gaussian random processes can be applied for eight basic variants of filtering problems, but engineering algorithms are presented only for the filtering problem with additive noises in mathematical model of the stochastic dynamical system.

The second part of the article describes five stages of the proposed methodical approach (the first three stages were described in the first part of the article):

4. Obtaining formulas linking a posteriori arbitrary order central moments with a posteriori cumulants for the filtered process.

5. Truncation and closure of a system of stochastic differential equations for a posteriori central moments of the filtered process.

6. Synthesis of high-precision optimal non-linear filters.

7. Setting known and computing missing initial conditions for a posteriori central moments of the filtered process.

8. Solving the optimal filtering problem (obtaining optimal estimate of the filtered process).

Evdokimenkov V. N., Lyapin N. A. Minimax optimization of enemy pursuit maneuvers in conditions of close air combat. Trudy MAI, 2019, no 106,

One of the main tasks facing a fighter aircraft consists in gaining the dominance in the air and holding it up, which is considered as the irremissible condition of successful of a warfare conduct for all kinds of armed forces. This task can be solved by destroying the enemy aircraft in the air. Besides, the air operations effectiveness while performing other missions also depends to a great extent on the crew ability to wage the air combat. Thus, the experience of aviation utilization in war conflicts is being carefully studied all over the world to search for tactical techniques, ensuring advantage in air combat.

The article presents the situation, when the attacking fighter aircraft tends to move through the active offensive maneuvering to the area of possible attacks, which configuration depends on characteristics of TSAs located on it. With this, the actions of an enemy aircraft performing passive defensive maneuver are aimed at evading the attack of the aircraft-fighter to prevent its entering the area of possible attacks of his aircraft.

All this is indicative of the need of employing the game approach to study offensive maneuvers of the aircraft-fighter.

The article presents an algorithm for the guaranteeing trajectory control of an aircraft-fighter for the pursuit-and-evasion task in conditions of a close air combat. It also presents modelling results, reflecting the effect of the attacking aircraft-fighter maneuvering capabilities on achieving positional superiority in an air combat.

Golomazov A. V. Decision-making information support method realizable in multi-agent system environment. Trudy MAI, 2019, no 106,

The need to improve the quality and efficiency of transportation and logistics management systems requires application of mathematical methods and models contributing to that increasing the level of intellectualization of decisions being made.

For this purpose, the proposed method employs a structure including the interacting subjects monitoring of transportation and logistics process (TLP), and selecting on its basis the significant content of factors of variables and characteristics, representing the basis of their decisions selecting. The article proposes to improve this quality by models and algorithms application, based on deterministic approach and fuzzy logic principles. Structurally, this method was regarded in the form of functional agents complexes developed based on the theory of multi-criteria selection in uncertainty conditions, game theory and principles of potential risks size and direction reduction evaluation of the interacting TLP subjects.

A possibility of periodical or continuous correction of the said content of significant variables appears herewith. This, in its turn, contributes to the decisions being taken adequacy level improvement. The intellectualization level increasing of the decisions being taken is achieved by developing complexes of functional agents being formed for the interacting TLP agents. These agents forming is performed in the method based on both deterministic approach and principles of fuzzy sets theory. Models and algorithms of functional agents allow realize information support of the TLP interacting subjects with regard for the risks and conflict situations. The method includes realized functional agents for negotiations process support, transportations planning and predicting.

The above said agents are interconnected and dynamically functioning in the multi-agent system (MAS) environment. Multi-functional agents developing by this method is base on:

- The multi-criteria theory of selection preferable solutions options in the uncertainty conditions;

- Matrix, bi-matrix, corporate and dynamic games, as well as strategies estimation with regard to Nash equilibrium;

- Ford and Fulkerson methods;

- Travelling salesman problem, knapsack problem and dynamic programming (rational route selection);

- Gantt charts plotting methods, and network scheduling and managing (transportations planning);

- Moving average method and approximation (predicting), ELECTRE method, and fuzzy logic algorithm (negotiation process support).

Romanov A. M. A novel architecture for Field-Programmable Gate Array-based Ethernet POWERLINK controlled nodes. Trudy MAI, 2019, no 106,

The article solves the problem of Field-Programmable Gate Array (FPGA)-based Ethernet POWERLINK controlled node implementation with minimal application of both logical cells and memory blocks. As a solution, a novel modular architecture is proposed, which resource intensiveness can be flexibly adjusted depending on the required functionality. Unlike previously known solutions, the proposed architecture does not employ soft-processors and does not require the incoming frames buffering. All data is processed “on the fly”, which allows the node to send a response to the request from the managing node with the minimum latency allowable by the Ethernet standard. The novel architecture employs one shared kernel for interaction with the Ethernet physical layer chip (PHY). This kernel forms a common data channel to which all other modules are connected. Each module processes frames of a certain type (synchronous, asynchronous, cross-traffic frame) and generates corresponding responses. Based on the proposed architecture, the first Russian Ethernet POWERLINK device was created, which compliance with the Standard was certified by Ethernet POWERLINK Standardization Group. By the results of experimental studies, it was demonstrated that the novel architecture requires from 3.5 to 9 times less FPGA logic resources, and up to 126 times less block memory for the of Ethernet POWERLINK devices implementation. The result of no less importance is the possibility of proposed solutions implementation based on FPGA chips from Russian vendors, including those in radiation-resistant version, which allows apply them in aerospace technology.

Ulybyshev S. Y. Mathematical modeling and comparative analysis towing vehicle schemes application to solve the problem of space debris objects removal to the disposal orbit. Part 1. Trudy MAI, 2019, no 106,

The presented materials of the study, split into four parts (separate articles), consider the complex issue of mathematical modeling and comparative analysis of the two types of remote control and associated with it design appearance of a promising spacecraft-towing vehicle (STV). The STV is designed to solve the problem of space debris objects (SDO) removal into the disposal orbit from satellite systems (SS) configuration. On the example of mission realization of the SDO removal from the specified orbital plane with return ensuring for the next object removal, scenario of the STV repeated application is being numerically computed.

Substantiation and workout of the design appearance of the prospective STV with two types of propulsion system (PS), such as liquid rocket engine (LRE) and stationary plasma engine (SPE), is being performed. The article presents the STV electric power supply system calculations and determines its weight and energy characteristics, as well as solar batteries size. Specifics and options of possible schemes of SDO removal into the disposal orbit were analyzed. Disposal orbits parameters have been determined for each STV PS type. The issue of the mean value computing of the STV SPE ballistic coefficient on the typical turn of functioning while SDO towing into the disposal orbit was considered. The boundaries of minimum possible altitude of the SPE application ensuring acceleration above the level of atmospheric deceleration were determined.

Scriabin Y. M., Potechin D. S. Determining the unmanned aerial vehicle horizontal flight path through the line of electrostatic sensors. Trudy MAI, 2019, no 106,

The article considers the problem of unmanned flying vehicles (UAV) detection and localization. This problem is associated with the UAVs rapid growth in number and relatively mild laws on the UAVs' regulation and flights organization. Thus, it is utterly important to ensure safety of critical facilities and highly crowded places fr om possible threats associated with the UAV application, as well as monitor the air space any time and under any weather conditions. To solve the problem, the authors propose to employ electrostatic monitoring technology.

It is worth mentioning, that conventional detection methods have problems with the low-altitude small UAVs detection. The advantage of electrostatic monitoring technology consists in the fact that this technology is capable provide information passively on low-altitude targets by monitoring changes in the electrostatic field in several points on the Earth surface. Besides, combining electrostatic monitoring technology with other existing detecting techniques may increase the probability of targets detecting.

The authors propose employing the time-frequency analysis for the electrostatic signal extraction. This method may be based on positions of the electrostatic signal extremes. The article defines analytical solution of the electrostatic problem of a point electrostatic charge movement above an infinite horizontal conducting plane.

The results of the analytical solution of the electrostatic problem of a UAV detecting by three electrostatic sensors lying on one straight line are presented. The article determined the theoretical lim it of the UAV detection by an electrostatic sensor. Theoretical equations for the UAV coordinates calculating based on the time-frequency analysis of electrostatic signals were derived.

The article presents experimental electrostatic signals received by an electrostatic sensor while the UAV flight. Two types of sensors were examined in the experiment. These are electrostatic fluxmeter and electrostatic probe.

The authors note that the electrostatic sensor system is potentially capable of detecting UAVs with a charge of 1 µC at the altitudes up to 100 m.

Vernigora L. V., Kasmerchuk P. V. Low-thrust spacecraft trajectories optimization by linearization method. Trudy MAI, 2019, no 106,

Problems of a low thrust spacecraft trajectories optimization are rather complicated problems of nonlinear optimization in the presence of constrains. The authors suggest applying linearization method modified for compound dynamic systems optimization for solving them. The Modified Method of a Linearization (MML) is quite a general method of nonlinear optimization problems solution. However, specifics of trajectory optimization problems of a low thrust spacecraft require confirmation of the MML application possibility to solve them. Two problems are being solved in this work:

- A flat flight optimization of a spacecraft with electric propulsion unit (EPU) and a solar sail between the Earth and Mars orbits;

- An optimization problem of a flight between two arbitrary non-coplanar near-Earth orbits.

The obtained results were compared to the results obtained by other authors.

The flat flight optimization problem of a spacecraft with EPU and a solar sail between the Earth and Mars orbits was solved for the two values of dimensionless initial acceleration of 1.0 and 0.02. An error of 0.37% in term of criterion, and 0.32% in the flight range angle was obtained for the first problem. In the second problem, the flight range angle error was 4.9%. The criterion value agreed within the put forward significant figures. In the flat flight optimization problem of a spacecraft with EPU and a solar sail between the Earth and Mars the results obtained with MML are better than the results obtained by the majority of other authors in the sense of criterion value. In the optimization problem of elliptic-to-geostationary orbit transfer for minimum time the obtained error in the criterion value was 0.05%, and control and trajectory nature coincided with the considered work.

Based on a number of the well-known examples the article demonstrates the MML steady work while solving the offered problems of trajectory optimization of a low thrust spacecraft with EPU and solar sail. A close agreement of the results with the results of other authors was obtained. This allows make conclusion on the possibility of MML application for solving the regarded classes of the trajectory optimization problems for low thrust spacecraft. The main advantages of the method are the large area of the solution convergence, which allows selecting trivial initial approximations, operating in terms of the loop problem without the necessity of obtaining additional structures of the transversability condition type etc. Rather slow convergence in the problem of transfering a spacecraft with EPU between two noncoplanar orbits, associated with the necessity of selecting a small-size area of the acceptable variations (the area in which the linear programming problem is being solved) to ensure the acceptable linearization level may be related to the shortcomings.

Ivanov S. V., Mogilevich L. I., Popov V. S. Longitudinal Waves in a Nonlinear Cylindrical Shell Containing a Viscous Liquid. Trudy MAI, 2019, no 105,

The problem of wave propagation in gas dynamics and elastic shells theory is being studied by linearized equations, propagation velocity being constant and equal to sound propagation velocity in unperturbed medium. Nevertheless, a certain set of occurrences, despite the dependent variables small values, are fully defined by perturbations propagation velocity dependence on dependent variables values and are studied basis on non-linear equations. These studies are performed by the perturbation method. The equations for an elastic body dynamics and liquid for the joint hydroelasticity problem are solved simultaneously, the corresponding boundary conditions impenetrable surfaces are being accounted for herewith. This approach is employed to sudy the non-linear deformation waves of elastic shells, containing viscous incompressible liquid.

The perturbation method for studying deformation waves in physically non-linear elastic cylinder shell, containing viscous incompressible liquid, was developed. The method of two-scale disintegration leads to Korteweg – de Vries generalized modified equation not having the exact solution. The surrounding elastic medium, the structure damping in the longitudinal direction and viscous liquid impact require the numerical solution of the equation.

There are no studies on viscous incompressible liquid impact on the non-linear wave process in elastic shells, the liquid being inside them, with considering its inertia movement local members. The presented article studies consideration viscous incompressible liquid impact on non-linear deformation wave propagation, which requires computer modeling, the liquid being inside the shell. The existing methods of mathematical models qualitative analysis do not fully allow studying deformation wave models in case of the shell filled with viscous incompressible liquid. Transition to initial discrete analogue models represents a far more universal method of models investigation. This publication studies the impact of the structure damping in longitudinal direction, surrounding the elastic medium and viscous incompressible liquid inside the shell on the wave amplitude and velocity. Systematic studying of this model wave movements in physically non-linear elastic shell is performed by the difference scheme in analogy with Crank-Nicholson for heat conduction equation.

Ivanychev D. A. Solving the mixed type axisymmetric problems for anisotropic bodies with mass forces. Trudy MAI, 2019, no 105,

A technique for solving the mixed axisymmetric problems for the bodies bounded by the coaxial rotating surfaces from transversal-isotropic material being under the impact of mass forces was developed in this work.

Its basis is a notion of the internal and boundary states, conjugated by the isomorphism, which allows establishing one-to-one correspondence between the elements of these spaces. The internal state includes the stress tensor components, deformation tensor components and displacement vector. The boundary state includes the forces and movements at the boundary, as well as mass forces. The isomorphism of the state spaces is proved, which allows finding the internal state to be reduced to the study of a boundary state isomorphic to it. The basis is formed based on the general solution of the boundary value problem for a transversely isotropic body of revolution and on the method of creating basic displacement vectors. The orthogonalization of the state spaces is performed. Finally, the desired state detecting is reduced to solving an infinite system of algebraic equations regarding the Fourier coefficients.

The article presents the solution of the problem with mixed boundary conditions for a cylinder. The material is a transversely isotropic siltstone with the anisotropy axis coinciding with the geometric axis of symmetry. Mass forces, imitating centrifugal inertial forces, act on the cylinder. Mechanical characteristics have an analytical polynomial character. The article presents the explicit and indirect signs of problem solution convergence, and graphical visualization of the results.

Britenkov A. K., Bogolyubov B. N., Deryabin M. S., Farfel V. A. Measuring electromechanical characteristics of a complex shape compact low-frequency hydro-acoustic irradiator. Trudy MAI, 2019, no 105,

Low-frequency hydro-acoustic irradiators are employed in a wide specter of practical applications: from the long-distance underwater acoustic communication and teleguidance to seismic-geophysical prospecting. The irradiator case manufacturing is one of the most complicated technological procedures while its fabrication and tuning. The proposed structure of the hydro-acoustic transducer with corrugated radiating sheath allows eliminate a number of problems such as sealing, tolerance to hydrostatic pressure, parameter spread and reliability. Mechanical transformation ratio measuring was performed to evaluate the suggested irradiator effectiveness. Distribution of oscillations amplitudes of the radiating case and active element were obtained by the laser vibrometry method. The article presents the comparison of the irradiator mechanical characteristics measuring results in the water with the results of its resonant frequency evaluation based on the simplified theoretical model.
Parameters of the suggested hydro-acoustic irradiator demonstrate the prospects of such converter design and manufacturing techniques. The maximum specific acoustic power of the experimental irradiator with the corrugated case exceeds 360 kW/m3, that is more than one and a half times more, than for the existing compact transducers. The irradiator material and case structure allow its transportation by aerospace carriers. Compact radiators of such design may be applied in small-sized and tiny hydro-acoustic systems, modems, control units, sonars and communication at frequencies from hundreds of hertz to tens of kilohertz.

Nguyen T. T., Tarlakovsky D. V. Antiplane non-stationary motion of electromagnetic-elastic half-space with account for piezoelectric effects. Trudy MAI, 2019, no 105,

The article considers homogeneous anisotropic unsteady electromagnetic-elastic motion related to the rectangular Cartesian coordinate system. The resolving system of equations includes equations of motion, Cauchy relations for deformations, Maxwell equations, as well as linearized generalized Ohm’s law and piezo-effects accounting for the physical relationships.

The article demonstrates that the antiplane movement is possible for the transversally isotropic medium in conditions of magnetic piezo-effects absence. It is assumed, that in this option the displacement and non-zero component of electric induction vector are set, and zero initial conditions and all components of stress and strain state are limited at the half-plane boundary.

The problem solving is being sought in the form of convolution functions of the specified displacement and electric induction with relevant surface Green’s functions. Laplace transformations in time and Fourier transformations in space coordinate are applied for their plotting. Analysis of images and characteristic equation revealed the intricacy of plotting the originals in an explicit form. Thus, the method of a small parameter, which is used as a coefficient, linking mechanical and electromagnetic fields, is employed. With this, it was marked that with the zero small parameter these fields are independent.

An explicit form of images of the first two coefficients of the corresponding power series was found. Their original are being found either by sequential Fourier and Laplace transforms inversion, or with the algorithm of joint Fourier and Laplace transforms inversion. In the most complicated case, the original is being presented in the form of definite integral, being calculated by a numerical procedure.

As a result, the problem solution is reduced to the two linear operators in convolution functions for the sought-for functions.

The examples of calculations are presented for the the material of a half-space in the form of quartz. The article demonstrates the dependencies on time and spatial coordinate of the resolving relations kernels, as well as electric induction and displacement for the concrete option of boundary conditions. Induction changes linearly along the coordinate, as the Heaviside function in time, while the displacement changes correspondingly as the Dirac delta function and linearly.

It is stated that single-error corrections introduced into the solution with due regard to piezoelectric properties of the medium have the order of the coefficient linking mechanical and electromagnetic fields.

Abramova K. A., Soudakov V. G. Flow Control Optimization by Tangential Blowing-Out on Transonic Airfoil. Trudy MAI, 2019, no 105,

Aerodynamic characteristics optimization of the transonic airfoil while flow-around control was performed based on numerical modelling. A jet of compressed air was blown-out from a small slot nozzle tangentially to the upper surface of the airfoil in the region of the shock wave. The blowing-out affects the shock wave and boundary layer interaction (SBLI), thus improving the airfoil performance.

The flow-around modelling was performed in the framework of the Reynolds equations. Computations were carried out in the 2D-setting for a mode with the Mach number of M = 0.72 and Reynolds number Re = 2.6 ∙ 106, computed by the chord, which corresponds to the testing mode in the wind tunnel.

Numerical optimization was performed to find optimal blowing-out parameters. With this, the blowing-out position, its intensity and the angle of attack were varied. Two objective functions were considered, namely, aerodynamic quality maximization and drag minimization at the constant lifting force. For the first objective function, position was being varied from 55% to 96% of the chord, and for the second one from 55% to 65% of the chord. The intensity was being varied from 100 to 300 kPa. The angle of attack was varied from 0.9 to 2.5 degrees.

The adaptive single-objective optimization was used. This method consists in employing Optimal Area Filling, Kriging response surface, and MISQP gradient algorithm (Mixed-Integer Sequential Quadratic Programming). Optimization revealed that for the lift-over-drag ratio objective function maximization, the optimal slot position was 83% of the chord, and the optimal jet intensity is Cµopt = 0.0049. For the objective function of Cxa minimization at a constant Cya ≈ 0.51, the utmost right position of the nozzle (65%) of all considered, and jet intensity Cµopt = 0.0051 are optimal. Tangential blowing-out with optimal parameters increased Kmax by 6% for the case of maximum quality; in the case of minimization of drag, Kmax increased by 3.5%, while the drag decreased by 1.1%.

Further the authors are planning consider more complex objective functions, accounting for the jet reaction contribution, as well as energy consumption for its blowing-out.

Zhbanov V. A., Kashevarov A. V., Miller A. B., Potapov Y. F., Stasenko A. L., Tokarev O. D. Studying icing under various conditions. Trudy MAI, 2019, no 105,

The article discusses the results of aircraft icing studying performed at TsAGI in the conditions of liquid droplet, crystalline and mixed clouds. The experimental set-ups for icing studying are described. Methods of ice crystals forming in the flow of icing wind tunnel are presented. The article presents data on the size and shape of the obtained crystals.

The results of the latest activity of TsAGI in international research projects on icing are presented. A number of coatings were studied under the conditions of run-back ice formation within the framework of the ICETRACK project.

The HAIC project (High Altitudes Ice Crystals) is studying the physics of icing under fully glaciated conditions. The experimental results on the formation of run-back ice on a wing profile model with a heated leading edge are described. The experiments were performed under conditions of crystal impingement for the cases of the initially dry heated surface and for that covered with an artificially created liquid film.

The physical-and-mathematical models of the of ice crystals interaction with both dry and wetted surfaces of streamlined bodies were developed.

For the case of a wetted surface, the water film movement along the surface is considered. The impact of the finite melting time of the crystals and the dependence of the effective suspension viscosity from the mass fraction of the dispersed phase on the processes occurring in the film are accounted for.

The movement of spheroidal crystals in the airflow is considered for the case of a dry surface. The model accounts for the orientation of non-spherical particles with respect to the air velocity vector. It is shown, that the process of ice accretion on the wing profile surface in the stream carrying oblate spheroidal crystals differs greatly from the case of a flow with spherical crystals

A numerical verification of the developed models was performed by comparison with the experimental data. The results of these studies are important for the problems of icing of engines and Pitot tubes in fully crystalline and mixed conditions.

Kirillov O. E., Mirgazov R. M., Golubev N. V., Petruhin D. A. Experimental studies of non-stationary aerodynamic characteristics of a helicopter airfoil vibrating in pitch angle. Trudy MAI, 2019, no 105,

There is presently no reliable theoretical approach capable to predict the unsteady aerodynamic forces acting on the airfoils at the helicopter blade sections operating near or beyond the dynamic stall angle of attack. However, numerous wind-tunnel tests of vibrating airfoils do provide a valuable experimental foundation for establishing phenomenological models, through which certain semi-empirical predictions can be made.

The article presents the results of experimental studies of non-stationary integral and distributed aerodynamic characteristics of the helicopter's airfoil in stationary and non-stationary modes. The stationary mode is a fixed airfoil in a uniform steady airflow. The non-stationary mode is an airfoil vibrating in the pitch angle in a uniform steady airflow. The studies were being performed in the vertical, closed-circuit TsAGI wind tunnel with an open test section at Reynolds numbers Re = 270,000 and 540,000, and at reduced frequencies from 0.06 to 0.26.

A particular feature of the study was application of two methods for aerodynamic characteristics determining, namely, a direct method of forces measuring using balance, and calculating forces by integrating the pressure distribution along the chord. The obtained results are compared to each other, and their satisfactory agreement in the stationary mode is shown.

Another feature of the study is the analysis of forces pulsations and pressures on the airfoil surface. In particular, using the wavelet analysis, a phenomenon called “frequency explosion”, specific for the dynamic stall of the flow, is demonstrated.

Krioukov V. G., Abdullin A. L., Nikandrova M. N., Iskhakova R. L. Reactions Mechanisms Reduction While Modelling The High-Temperature Flows in Nozzles. Trudy MAI, 2019, no 105,

Modern models for high-temperature chemically non-equilibrium flows calculating in nozzles are based on the detailed chemical kinetics. For this purpose, a certain reaction mechanism is built into the model. An expert approach is usually used to substantiate (reduction) this mechanism. However, it requires significant time consumption, and is performed only by the experienced specialists.

However, a number of automated reduction methods (an automated approach) are already developed thus far, and widely used. The article proposes a procedure for reducing the reaction mechanisms for chemically non-equilibrium flows in aircraft engines nozzles. This procedure consists of two methods: DRGEP (Directed Relation Graph Error Propagation) method and method of engagement with an adaptive threshold. The DRGEP method is focused on selection of only unimportant species and removal them from reaction mechanism along with reaction triggering them. If insignificant reactions still remain in the mechanism, they are removed by the method of engagement.

This procedure is included in the program for calculating chemically non-equilibrium flows in a nozzle. It generates a reduced local mechanism (L-mechanism) from the initial (redundant) set of reactions for the given values of the parameters αok, Pос , rm. Joining the L-mechnisms, obtained with the other values of these parameters it is possible to form a global mechanism (G-mechanism) for the specified area of their variation.

The cre ate d procedure validation was performed for the combustion products flow in the profiled nozzles for the LRE engine fuel (“О2 + kerosene” and “N2O4 + C2H8N2”) for a wide range of variation: oxidant excess ratio ( αok = 0.7…1.2); pressure (Pос = 20…100 atm.); minimum radius (rm = 0.006….0.06 m) with a geometric degree of expansion fa = 50.

With an acceptable error in the flow characteristics prediction:

a) G -mechanism recombination of the working medium “О2 + kerosene” was reduced from 47 reactions and 16 substances to 15 reactions and 9 substances (H , H2 , O , O2 , CO2 , H2O , CO , OH , HCO);

b) G -mechanism recombination of the working medium “N2O4 + C2H8N2” was reduced from 82 reactions and 26 substances to 27 reactions and 15 substances (H, H2, O, O2, CO2, H2O, CO, OH, N, N2, NO, NH, HCO, HNO, N2O).

Firsanov V. V., Pham V. T. Stress-strain state of the spherical shell based on the refined theory. Trudy MAI, 2019, no 105,

The classical theory does not produce a satisfactory compliance with practice while calculating the stress-strain state of structural elements in the areas of fixture and action of local and rapidly changing loads, as well as structural elements made of heterogeneous materials. To describe the volumetric stress-strain state, it is necessary to develop a refined, with respect to the classical theory of the Kirchhoff-Love type, theory based on the three-dimensional equations of the elasticity theory.

The presented work proposes an option of the refined theory of the stress-strain state calculation of isotropic shells. The mathematical model is built based on the 3D equations of the elasticity theory. The problem of 3D equations reduction to the 2D equations is being solved by representing the desired displacements with polynomials over the normal coordinate of two orders higher relative to the classical theory.

The system of differential equations of equilibrium in displacements with variable coefficients was obtained using the Lagrange variational principle. The aforesaid system of equations solution was being performed by methods of finite differences and matrix run. As a result, the displacements in the grid nodes were obtained, and splines were used for their approximation. The shell deformations are being found by dint of geometry relationships, and tangential stresses are determined from the Hook’s law relationships. Lateral stresses are obtained by direct integrating of the equilibrium equations of the 3D elasticity theory.

A hemispherical shell rigidly clamped along the lower contour of the base is considered as an example. Comparing the obtained results with the data of the classical theory allowed establishing that the refined theory should be used while studying the stress-strain state of the spherical shell near the zones of the stress state distortion. For example, it should be applied in the vicinity of a rigidly clamped edge, since the maximum stresses in this zone are being refined substantially.

Neglected in the classical theory, the transverse normal and tangential stresses in the border zone are of the same order as the maximum stress values corresponding to the classical theory. Such high levels of additional stresses should be accounted for while assessing the shell structures strength and durability.

With distancing from the edge the stresses, obtained by the refined and classical theories are practically concurring, which confirms the fidelity of the obtained results.

Philatov V. I., Borukaeva A. O., Berdikov P. G., Kulakov D. V. Developing methods for noise-proof signals distinction. Trudy MAI, 2019, no 105,

The purpose of this work consists in selecting an optimal device for processing a complex signal, ensuring a low noise level. The article considers the operation principle of the scheme for forming and processing a complex signal with informational modulation. It describes also the receiver operation, which performs the inverse transformation of the signal. The authors consider several types of demodulator schemes and their principle of operation. Based on the existing options for schemes structures that solve the problem of the channel selection in which the signal is located, the comparative analysis of the options for the solver structure, allowing substantially reduce the interference impact, was performed. In conclusion, the brief comparative review of the proposed solver units is carried out. The authors make conclusion on selection of a certain type of solver unit that increases the noise immunity of complex signals due to selection of the signal certain parameters.

Relevance of the presented work theme is substantiated primarily by the necessity of developing the new techniques and methods allowing detecting, classifying and distinct complex signals of this or that radio-receiving unit, since more and more radio-electronic means employed onboard the civil and military aircraft are operating with complex signals. The most widespread complex signals herewith are the signals based on linear M-sequences. Application of complex signals is stipulated by their pronounced noise-proof characteristics necessary in conditions of radio channels operation in jamming environment. The radio channel saturation by the complex signal herewith requires the receiver quite accurately detect exactly its own radio signals. In this regard, it is necessary to develop an approach allowing determine the class and distinct the type of signal-code structure to step-by-step simplification of the algorithm for signal detection, identification and processing.

Krylov V. P., Pronin T. Y. Relative statistical evaluation of printed circuit boards mechanical characteristics technological non-uniformity. Trudy MAI, 2019, no 105,

A model of statistical factor analysis was applied for a batch of 12 samples of glass-epoxy double-sided and multilayer printed circuit boards (PCBs) to examine the engineering tolerance of the average values of elastic modulus and mechanical loss coefficient. Experimental estimates of the variations were obtained in the form of ratios of standard deviations of the technological and measuring errors.

Samples of various thickness with a shape of rectangular plates with 130 by 60 mm size were alternately secured in the fixture on a vibrating table by the four screws on the corners. Registration of frequency characteristics near the first resonance was performed with the IMV shaker i220 in the sinusoidal vibration mode within the frequency range of 5 ... 2000 Hz with a vibration acceleration of 2 g. In this frequency range the device has no natural resonances.

The measurement cycle consisted of two series of measurements of each sample, performed within one working day, with one-hour interval between each series. Three cycles were performed: before and after the heat treatment in a convective reflow oven, and after 6 months of storage at room temperature.

The numerical values of the mechanical characteristics were measured by solving inverse ill-posed problems using SolidWorks Simulation program. The calculated model of factor analysis assumes the random nature of technological and measuring errors, as well as a linear correlation between the series of measurements. The Pearson correlation coefficient uniquely determines the relative statistical evaluation of the technological error of the aforementioned mechanical characteristics of the PCBs within the batch.

The relative estimate of the elastic modulus variation equals to 14 and does not depend on the heat treatment and storage within the confidence interval of the sample value of the correlation coefficient. The corresponding estimate of the variation in the coefficient of mechanical loss, initially equal to 3, increases by more than 50% after the heat treatment and returns to its original values after storage.

Recommendations on the application of the results obtained while the vibration strength testing of electronic devices of the unmanned spacecraft are given.

Zvonarev V. V., Popov A. S., Khudik M. Y. Error probability computing technique for symbol-by-symbol receiving of discrete messages in the presence of interference. Trudy MAI, 2019, no 105,

The purpose of the article consists in obtaining analytical expression for of error probability computing of symbol-by-symbol receiving of discrete messages in the presence of interference.

The article presents the analysis of optimum symbol-by-symbol coherent correlation reception without noise, the principles of modems' circuit and constructive implementation, methods of achieving high noise immunity by transmission and reception of the phase-shifted keyed signals in satellite radio channels, in the TV transmission channels, computer simulation of the correlation receiver.

Mathematical formalization of the device in the form of equations is the solution of statistical problem of finding addition to the probability determination of the correct exceedance of one Gaussian random variable over another in the presence of negligible algorithm of optimum reception deliberate, harmonious and coherent with signal, noises.

The article presents the technique and results of error probability calculation of the of symbol-by-symbol reception of binary phase-shifted keyed opposite signals in the presence of the harmonious co-phased noise, not considered by the correlator. Optimum symbol-by-symbol reception of discrete messages is performed by the correlation receiver, or the matched filter configured on the signal in the noise absence, in the presence of receiver noises only.

The approach considered in article is necessary for calculation of error probability of character recognition the presence of the additive noises of various structures, which are not considered by the reception algorithm of the manipulated radio signals.

The developed technique application is prospective for potential noise stability calculation of the symbol-by-symbol reception in conditions of presence of the deliberate noises of various structures at a radio channel.

Smirnov A. A. Applying digital predistortion introduction technique to improve energy efficiency of info-communication radio equipment. Trudy MAI, 2019, no 105,

In recent years, the explosive growth of portable info-communication devoces is being observed. Several factors became the catalyst of this development, including Internet of things (IoT) development, a wide proliferation of UAVs (unmanned flying vehicles), the fourth industrial revolution (4.0 industry) etc. These conditions impose a complex of requirements to the info-communication electronic equipment, responsible for data transmission. One of the basic tasks is energy efficiency enhancing of the radio devices under development.

The article considers methods of digital predistortion (DPD) introducing and envelope tracking (ET) as ways of efficiency increasing of info-communication means, and performs a comparative analysis of both methods implementation.

Radio module is the most energy-consuming part of modern radio communication devices. It consumes up to 50% of the total battery charge. Power amplifiers, in their turn, are the main energy consumers of the radio modules. They consume up to 50% of the radio module total consumption as well [1].

Due to its non-linearity, the amplifier requires a precise selection of the input level to ensure its operation in linear mode. However, this requirement contradicts to the need for the amplifier most effective utilization, i.e. obtaining the maximum possible signal at its output. A compromising solution consists in finding an optimal operating point.

Modern standards of communication and data transmission are very sensitive to various kinds of nonlinearities. This is determined by the high peak to average power ratio (PAPR) as well. The higher this value, the less time the amplifier runs at maximum power.

Ananev A. V., Stafeev M. A., Makeev E. V. Developing communication organization method employing short-range unmanned flying vehicles. Trudy MAI, 2019, no 105,

The article proposes a method of radio communication employing a group of short-range UAVs-repeaters allowing ensure information exchange in conditions of the enemy counteraction. The main correspondents of the article are members of the reconnaissance and strike contours involving manned and unmanned short-range aircraft..

The disadvantages of this communications method when employing a single UAV in the information area are the high vulnerability of the transmission system due to the destruction of a single UAV-repeater, and insufficient communication range.

The purpose of this article consists in providing a method of organizing application of groups of unmanned aerial vehicles in reconnaissance and strike contours, including those involving aviation.

Analysis of the radio communication structure employing a single UAV-repeater is presented. The necessity of using a composite communication channel formed by the groups of unmanned aerial vehicles repeaters is substantiatied.

The result of the of the proposed method application is the ability of high-quality information exchange between the subscribers located outside of the direct visibility zone within the required period of time.

The positive effect is being achieved due to the fact, that the method comprises communication establishing between subscribers by deploying a radio link for a limited period of time (required for the task accomplishment) in the areas of interest. These are the areas where the deployment and application of terrestrial communications is hampered (difficult terrain, swamps, fires, electromagnetic incompatibility, radio-electronic counteraction). The article presents the results of the method practical approbation.

Chistyakov V. A. Algorithm for adaptive noise filtering in digital antennae arrays of satellite communication. Trudy MAI, 2019, no 105,

Currently, no radio equipment can do without an antenna system, ranging from primitive radios to complex space systems. So on modern communication spacecraft, complex antenna arrays (AR) are installed, which differ in their configuration, a set of elements and a number of other important parameters. The main trend of space technologies development is noise immunity of communication channels in conditions of both peace and wartime. The article proposes an algorithm for adaptive filtering of useful signals against the background of various disturbances, which allows ensure necessary interference protection of communication channels during messages transmission

The adaptive algorithm is based on the method of direct inversion of the signals correlation matrix at the input of the antenna system. The main idea of the algorithm consists in obtaining an optimal weighting factors vector that allows changing the amplitude-phase distribution of the antenna array in such a way that deep sags are formed in the directional pattern (DP) in the direction of the interference.

The optimal weighting factors vector estimation computing is being performed by direct inversion of the interference correlation matrix. This method implicate creating a sample estimate of the correlation matrix using a pack of training vectors.

The advantages of this algorithm include a high rate of convergence of the weight coefficients vector and a rather deep formation of sags in the DP of AR in the direction of interference. Nonetheless, this algorithm is difficult to implement, in the case when the correlation matrix is degenerate, which makes its inversion impossible. This problem occurs when the signals from the outputs of the antenna array elements are linearly dependent.

However, there are two ways to solve this problem.

The first method involves application of the so-called diagonal load, which allows increase the difference between the maximum and minimum values of the correlation matrix, allowing thereby solve the singularity problem. Also, this method is noteworthy in that it allows evaluating the correlation matrix when the number of training pack is less than the number of the antenna array elements.

The second method involves increasing the number of training pack so that their number is at least twice the number of the antenna array elements.

The process of adaptive filtering is represented by the example of a flat rectangular 25-element array antenna, which input receives useful and interfering signals. The narrow-band signals with FM4 modulation, acting within the main lobe of the directional pattern, are used as the useful signals. The interference, in turn, is represented as a white Gaussian noise with a wide spectrum. In consequence of the algorithm modeling, the author has formed an adaptive antenna array directional pattern, and presented a useful signal spectrum passed the adaptive processing, which allowed filtering-out the interfering signals components.

Thus, the performed simulation has confirmed theoretical calculations of the adaptive filtering algorithm for the direct inversion of the correlation matrix, which makes it attractive for applicaiton in modern digital antenna systems.

However, the main factors affecting the technical characteristics of the adaptive filtering algorithm should be noted as well.

The first factor affecting the high characteristics of the above-described algorithm is, in the first place, its own noise caused by analog and digital equipment included in the antenna system.

In particular, the internal noise of the analog-digital path is determined by the jitter of the aperture, jitter from sampling, and differential nonlinearity.

The second factor is the length of the sample of training packs. As was said above, the correlation matrix of the input signals might be degenerate, which would lead to an inaccurate estimation of the weight coefficients. Thus, to avoid this situation, it is necessary to increase the number of training pack.

The third factor, causing the operation errors of the adaptive filtering algorithm is the decorrelation of the signals in the receiving channels of the digital antenna array. This is due primarily to the nonidentity of the amplitude-phase characteristics of the antenna array channels, as well as the moments of signals sampling discrepancy in them. Thus, decorrelation of signals leads to the fact that the non-diagonal elements of the correlation matrix of the input signals decrease in modulus, which causes an incorrect estimate of the weight coefficients.

Vasil`ev V. A., Fedyunin P. A., Danilin M. A., Vasil`ev A. V. Problem issues of information support of striking aircraft complexes management. Trudy MAI, 2019, no 105,

The article substantiates the need for further improvement of the information supply organization for the management striking aircraft complexes with the direct support of the Ground Forces. The analysis of the information supply management organization, which means information collection, processing and transmission in time, was performed. The impact of the message delay in the control channel due to the perturbing action on the effectiveness of the striking aircraft complex control was estimated. The contradiction between the need to increase the intensity of control information transmission to maintain its adequacy and the limited capacity of the aviation radio network capacity was revealed.

The order of access to common time-frequency resources of aviation radio networks is determined by the random multiple access algorithm with carrier verification, for which the system queuing models are well-known. Information flows through logical connections are represented by a stationary Poisson flow, and the transmission medium is represented by a multiple-access radio channel Application of this model allows determining the pack delay time as a function of the information exchange intensity and network parameters. The steady state of the network is characterized by low latency and the highest performance. An unstable state is characterized by irreversible latency increase, and performance decrease. Representation of the information exchange process without introducing model elements into the network, which account for the state of the network under the impact of the intentional interference may lead to an error in determining messages delay.

The effectiveness of target indication and guidance of striking aircraft complexes on the maneuvering ground target depends on the delay of managing messages, which leads to an error in determining the information damage management.

This contradiction resolution may consist in the information intensity updating of the assignment control, at which specified permissible information damage in predicted conditions of situation and a priori known dynamic characteristics of target will not be exceeded. With a large number of options for the situation and target movement parameters, this approach has low efficiency. Its more advanced version is represented in adaptive traffic intensity control in the control channel of the striking aircraft complexes or speeds of logical connections in aviation radio network.

Practical implementation of this approach will ensure the required timeliness of information exchange while target indication and guidance, and increase the likelihood of the guidance of striking aircraft complex on the target.

Titov A. G., Neretin E. S., Dudkin S. O., Brusnikin P. M. Developing the onboard data server for application as a part of radio-electronic equipment employing the concept of integrated modular avionics. Trudy MAI, 2019, no 105,

Modern onboard equipment (OBE) complexes include the systems for which storage and processing of a large amount of information is required. The real time data access is required herewith.

Analysis of the existing data storage systems revealed that on the samples of domestic aircraft, information is most often stored on computers which main functions are not data storage, but data processing. The main part of computing resources is spent on running applications. This leads to slow processing of requests to the database, which in turn affects the operation speed of the systems that need data from the database or that are writing to the database.

The article is devoted to the development of an onboard data server (BSD) with employing the concept of integrated modular avionics (IMA) for the onboard equipment (OBE) complex of the medium-range MS-21 aircraft.

The main functions performed by the BSD are storing the aircraft systems databases (DB) (such as on-board maintenance system and air navigation system), supporting database management systems (DBMS) for these databases and ensuring access to them at the request of functional applications as part of OBE.

The BSD represents computing platform of a separate data server ensuring execution of several independent functional applications and interaction with on-board equipment via the interfaces AFDX, USB, Ethernet, RS-232.

The article proposes and describes four operation modes, namely, starting mode, operating mode, advanced monitoring and technological modes. Switching algorithm between the OBD operating modes is described.

The authors propose requirements for the onboard data server, software requirements, architecture and design of the onboard data server.

The BSD employing will allow relieve the load the computing kernels of the functional applications of aircraft systems, simplify the work of the maintenance personnel, interacting with the onboard maintenance system and the aircraft crew, when compiling the flight plan using navigational data processed on the server.

Kosachev I. M., Chugai K. N., Rybackov K. A. Methodology of random processes high-precision filtering in stochastic dynamic systems with fixed structure. (Part 1). Trudy MAI, 2019, no 105,

The article presents a methodical approach to high-precision nonlinear filtering of multidimensional non-Gaussian random processes in continuous-time stochastic dynamical systems with a fixed structure. The high accuracy of the developed algorithms for the optimal nonlinear filtering problem is stipulated by application of a posteriori higher order central moments of the filtered process. The adaptability of the developed high-precision nonlinear filtering algorithms is ensured by computing in real time a posteriori skewness and excess kurtosis for all phase coordinates of the filtered random process. Further, they are compared with the threshold values corresponding to the Gauss random process, and, if necessary, accounting for by iteration way filtering algorithms of a posteriori higher central moments of the filtered process.

The methodology under consideration for high-precision nonlinear filtering of multidimensional non-Gaussian random processes may be employed for eight basic options of filtering problems. Though engineering algorithms are presented only for the problem of filtering with adaptive noises in mathematical model of the stochastic dynamic system.

The methodical approach to high-precision nonlinear filtering of multidimensional non-Gaussian random processes can be used for eight basic variants of filtering problems, but engineering algorithms are given only for the filtering problem with additive noises in the mathematical model of the stochastic dynamical system.

The first part of the article describes three stages of the proposed methodical approach:

  1. Obtaining universal stochastic integro-differential equations for a posteriori arbitrary order central moments of the filtered process.

  2. Obtaining stochastic integro-differential equations for a posteriori the required order central moments based on the given mathematical model of the stochastic dynamical system.

  3. Obtaining stochastic differential equations for a posteriori central moments of the required order by expansion of averaging in corresponding stochastic integro-differential equations by the non-linearities statistical approximation method.

Other stages of the proposed technique will be described in the second part of the article.

Zhukov S. V., Danilin A. I. Infrared optoelectronic transducer of the helicopter main rotor deformation state. Trudy MAI, 2019, no 105,

This article deals with developing a method and a device for a helicopter main rotor deformation state. It proposes an additional infrared channel for the main rotor monitoring. The article considers fundamentals and operation conditions of the proposed method and device. The experiment was performed with the blades models, manufactured from various materials. The experiment was being conducted for various setting angles of the blade model. As a result, the studies of the blade models setting angles impact on the reflected flux formation were conducted assisted by the setting angle adjusting mechanism. Amplitude characteristics, showing the dependence of the signal amplitude from setting angle of the blade model, were obtained. Natural and technogenic sources of jamming radiation, and the atmosphere bandwidths are presented. Natural interference of the infrared band were studied experimentally. For this purpose, an experiment with infrared radiation detector was performed. As an addition to the experiment, the impact of natural sources of infrared radiation and optical properties of the atmosphere on the sensors operation was considered theoretically. Based on the considered data, a part of the infrared band spectrum was offered for utilization for the subsequent development of the sensors and systems. The article presents the description of the experimental test bench for the workout of separate propositions of the method and separate units of the device. Conclusions on the applicability and further development of the method are drawn.

Baranov N. A., Taipova D. R. A device for space particles parameters measuring and evaluating their impact on the satellite-building materials. Trudy MAI, 2019, no 105,

The article describes the effect of small fractional space debris on satellite-building materials that are most vulnerable to the impact of dust particles, such as various optical products materials (portholes, protective glasses, lenses, mirrors, solar batteries, thermal control coatings and electrovacuum insulation).

Collision with particles of the centimeter-sized space debris is fatal for a satellite, and the space stations may be damaged. A head-on collision with millimeter-sized particles will cause the satellite or station equipment failure or destroy it. The smaller particles are cannot inflict significant damage to satellite equipment, but may lead to degradation of the fragile parts.

The article proposes the design and principle of operation of a flat panel cosmic dust detector. This device makes allows perform complex spatial registration of the impact of meteoroid and technological particles on the spacecraft. The basis of the device design is a body made of nanocomposite material or beryllium aluminum alloy with mechanically fixed cells containing the following materials: a piezo-active polarized PVDF film, a thin-film capacitor sensor, a phosphor, various satellite-building materials, and an aerogel layer for trapping and further post-flight study of fractional space debris. The detector registers and measures parameters of impacts based on several physical phenomena, such as an MDM structure breakdown consisting of a dielectric layer and metal conductive layers deposited on it, phosphor glow and a signal from the piezosensor. The design being described includes special target inserts from vulnerable satellite building materials to control the degree of their degradation under the impact of a dust particles stream.

Kuksenko S. P. Simulation of a spacecraft noise immune power network. Trudy MAI, 2019, no 105,

The article presents a generalized characteristic of a spacecraft power grid and tendencies of its improvement with regard to power buses application. It proves the relevance of mathematical modelling employing with account for electromagnetic compatibility requirements while the system designing. The article presents a brief description of the software prototype developing specifics in TUSUR for designing elements of the spacecraft distribution network. The prototype is based on the TALGAT system, which functional was updated. The system was employed earlier while fulfilling several space projects. TEM-approximation, the method of moments and the modified method of nodal potentials for calculating parameters of the of transmission lines segments and the response at the end of the structure were used as the mathematical basis for the software prototype developing. Such an approach allows significant simulation time saving, and thus, considering a greater number of possible topologies of the power supply network, as well as speeding up the process of its designing, as compared to electro-dynamic simulation.

The article presents the simulation results of the power bus and wire taps connected to it, as well as the development of a module for evaluating the effectiveness of shielding enclosures with apertures and a database of conducted interference signals. Computing of N-norms used to characterize the signal in the time domain and determine the limit of susceptibility of the equipment were also implemented. Thus, they may be used to evaluate not only the immunity of the spacecraft power supply network, but also its reliability, as well as to identify the most critical network nodes to eliminate product failures during operation.

The approach to reducing the time spent on simulation was tested. It is demonstrated, that the simulation can be accelerated up to 19 times when the frequency dependence of the relative dielectric constant of the dielectric is accounted for.

Tleulinov M. K., Jafarzade A. . On reaction determining in connections of combined lifting member and control surfaces of low aspect ratio. Trudy MAI, 2019, no 104,

The article considers the combined structure, consisting of a lifting member and control surface, connected in three or more points, i.e. statically undefined manner. The reactions value of such structures is determined not so much by the external loading as by the displacement compatibility conditions of lifting member and control surface hinged to it. Thus, it matters how the structure is being modeled, and what design models are being employed. The issue of the interrelation of reactions in the control panels hinging nodes, obtained while modelling according to the beam and plate analogies at small aspect ratios is studied. It was established earlier that the difference in reactions, obtained with the rod and plate models, decreased with the structure aspect ratio increase. It was close to zero at medium and high aspect ratio. The presented article studies the issue on the interrelation of the reactions in the control panels hinging nodes, obtained while modelling according to the rod and plate analogies at small aspect ratio. The frontal (laying in the control surface plane) reactions are being evaluated. It was established, that with small aspect ratio the divergence of the rod and plate values of the frontal reactions depended greatly on the aspect ratio and relative thickness. With this, the less the aspect ratio, the greater the dependence from the relative thickness. The difference between the reactions decreases with the relative thickness increase.

Thus, there is no need to use the plate model while determining the reactions value in the control surface hinging nodes at the lifting member length to width ratio greater than two. If this ratio is less, this necessity occurs. With this, the less the aspect ratio, the more the need for the plate analogy.

Khatuntseva O. N. Analytical method for velocity profile determining of the turbulent fluid flow in the flat Couette problem. Trudy MAI, 2019, no 104,

Despite the great progress related to the solution of hydrodynamical problems both for the laminar and for turbulent flow modes based on the numerical solution of Navier-Stokes equations (NSE), the main question is not resolved at the mathematical level of rigorousity: whether the NSE describe both these modes.

The Navier-Stokes equations represent the Newton second law for the selected small enough but finite volume of the isothermal liquid, and describe this volume acceleration under the action of the force caused, on one hand, by the pressure gradient and external forces, and, on the other hand, by viscous force action on the surface of this volume.

In case of the deterministic, i.e. laminar, liquid flow mode the NSE correctness for such process describing is undoubtful. However, while transition to the turbulent liquid flow mode a great number of additional stochastic degrees of freedom occur. In this regard, the issue on the possibility of such system description by the deterministic Navier-Stokes equations remains open.

It is obvious that the issue on the possibility or impossibility of the turbulent flow mode description based on the NSE can be considered in the simplest way on the example of solving those hydrodynamic problems, which allow analytical solutions. Regrettably, due to their complexity, the NSE have such solutions only for the restricted set of problems for very simple geometries.

The flat Couette problem is one of such problems. The transition to the analysis of Navier-Stokes equations in the space expanded via the additional variable, which specifies the entropy production due to the excitation of the stochastic pulsation in the fluid flow enables to find two solution of this problem. One of them corresponds the laminar flow mode, and the second corresponds the turbulent flow mode. is characterized by the linear velocity profile over the complete liquid flow domain. The second one is realized for the high enough Reynolds numbers, and is specified by the velocity profile proportional to the hyperbolic sine with parameters dependent on the Reynolds number.

The critical Reynolds number, at wich the laminar to turbulent flow mode transition is possible, is determined. Comparison with the available experimental data is presented.

Baklanov A. V., Makarova G. F., Vasil'ev A. A., Nuzhdin A. A. Gas injector geometry changing impact on the fuel jet spread angle. Trudy MAI, 2019, no 104,

Ensuring of qualitative fuel supply to the combustion chamber primary zone is an important process affecting the fuel burn-up characteristics. Thus, the injector structure impact study on mixture, spread angle and fuel jet flow structure is an actual problem.

The article considers the combustion chamber injector of the NK-16ST gas turbine engine as the subject of research.

The injector contains a screw in its structure serving fuel swirling device, which allows classify it as a centrifugal gas injector.

This work performs research work on studying changes of a swirled fuel jet supplying method impact on the angle of fuel spray cone forming. For this purpose the installation was developed. Injector and flame stabilizer with a swirler, to which compressed air is supplied, are being fixed in the working section of the installation. The installation structure makes provision for separate control of the compressed air supplying to the air and gas pipelines.

A small metal balloon filled with aluminum powder to admixture it to the air is installed in the fuel line for the flow pattern visualization. A screen with the graduated scale is being installed to fix the spread angle of gaseous fuel and spread angle axial line shifting behind the injector

The results of the study allowed reveal that changing the distance between the screw and injector output section did not significantly affect the opening angle of the swirled jet, while the diameter change of aperture in the injector output section affected significantly the opening angle of the swirled jet. Flow characteristics of injectors were plotted. Structural measures allowing affecting the cone angle of the gaseous fuel and hence forming the necessary fuel burning process parameters were determined.

Varyukhin A. N., Ovdienko M. A. OpenFOAM software verification using seaplane gliding modelling problems. Trudy MAI, 2019, no 104,

Drag force, seaworthiness and gliding stability of marine aircraft, including seaplane, amphibious aircraft and ekranoplan are the main characteristics which define their operational capability. Currently, the hydrodynamic layout development is being performed by the towing tests of dynamically scaled models. The reliable design procedure for hydrodynamics and seaworthiness performance determining could have allowed decrease the number of experiments and increase their efficiency. For this purpose, the open source computational fluid dynamics toolbox (OpenFOAM) verification was performed for hydrodynamic gliding and fast water entering problems

The test study was performed based on several experimentally validated typical problems. The keeled plate gliding on a partial and full width, keeled body on a regular wave, keeled plate water entry, and gliding with a stern interceptor are among them.

A comparison of the experimental and numerical results revealed that OpenFOAM accurately simulates the flow pattern and free surface of keeled planning plate. It also replicates the lift force and pitch moment (within the limits of the experiment accuracy). Unfortunately, the match of computational and experimental results for the drag force was no achieved. In general, this accuracy level can be considered as satisfactory for the certain class of problems where the drag force determining is not principle.

Further, it is necessary to perform parameters variation of the turbulence model, computations with more detailed computational grid, as well as perform simulations without the near-wall functions in the boundary layer etc.

A good agreement of computational and experimental values of hydrodynamic lifting force acting on flat-keeled body while its passing through the series of regular waves was achieved. A close agreement for both flow patterns and hydrodynamic lifting forces, acting on the bodies, was achieved while modelling the water entry by four different keeled bodies. A good agreement of additional lifting force and drag force was obtained while gliding modeling of a flat-keeled plate with stern interceptor.

As a conclusion, it can be recommended to apply the OpenFOAM open source software for obtaining the hydrodynamic lift force and the moment acting on the body while gliding and entering the water in steady state and transient cases. It is necessary perform additional studies to determine the drag force of gliding bodies accurately.

Sorokin F. D., Zhang H. ., Popov V. V., Ivannikov V. V. Experimental verification of the roller bearing energy model for aircraft engines supporting nodes modelling Part 2. Studying the rings bending impact on the full-load characteristic in case of a bearing unfixed in the bearing race. Trudy MAI, 2019, no 104,

Bearings with flexible rings analysis is presented in a vast number of technical papers [3-11]. One of the first attempts to perform analysis of the bearing with account for its structural deformations was made by Jones and Harris [3]. They incorporated the outer ring flexibility into the model, although for a very particular case such as the support of an idler gear in a planetary transmission. Later Filetti and Rumbarger [4], developing a general method for predicting the impact of sthe tructural support upon bearing performance, treated the outer ring as a set of beam elements and used 1D linear springs for the rollers in contact. This model proved to have good correlation with experimental data. However, a priori knowledge on the attachment points of the outer ring significantly limits the approach applicability. Moreover, as with the of Jones and Harris formulation [3], only one of the bearing rings is deformable in the Filetti and Rumbarger model [4]. The recent model of Cavallaro et al. [5] considers deformations of both bearing rings. In contrast to the previous formulations, the problem of the rings deformations determination was formulated in terms of forces. The model considered also the centrifugal expansion of the rings, the cage rotation and the lubricant presence. Balykin et al. [6] has also recently studied the effect of the bearing races compliance, although limiting the discussion to some specific cases of external loading.

To verify the energy model of the roller bearing, a full-scale experiment was performed with the universal Zwick/Roell Z100 test machine. The roller bearing of 12309KM type was being loaded by the local compressive load acting on the outer ring. The bearing outer ring deformation was being measured by the strain gage. The experimental data comparison with the numerical results obtained by FEM and the results obtained from the previously developed energy model also confirmed the impact of ring compliance on the elastic characteristic of the bearing. The study revealed that in the absence of structural elements that exclude the rings bending (shafts, clips), the energy model of the roller bearing should be supplemented by a technique for accounting for the rings deformation.

Turanov R. A., Pykhalov A. A. Analysis of the "ear-plugˮ type structure operation by the finite elements method and by the contact problem of elasticity theory solution. Trudy MAI, 2019, no 104,

The wing to fuselage connection is one of the most critical part of any aircraft. Here, in most cases, the wing represents the main bearing surface, and the fuselage is the load. With the wing design complication, such as a caisson type, the urgent task of analyzing its fastening elements with the fuselage arises to obtain the most advantageous design in terms of mass and reliability. This problem has been traditionally solved by of empirical methods. This solution can be significantly expanded employing highly efficient theoretical methods that allow analyzing both the parts stress-strain state (SSS), and their conjugation conditions.

The results of experimental studies presented in the works of E.V. Ryzhov [7], show that while the joint structure loading, out of the total amount of deformations 80% from them are those at the parts joints, and only 20% are deformations of the parts themselves. Thus, in contrast to its monolithic analogue the operability of the prefabricated structure is determined by both the strength of the parts and the conditions of their conjugation (layout) aimed at ensuring the minimum level of stress concentration in the joints assemblies of the aircraft structure.

With the empirical approach, when solving design problems of this type, there is a need to create a large number of field test samples. As a result, the total and time costs are rather large. With the advent of modern computational technologies based on FEM, new computational techniques have appeared that allow the most detailed study of the perception of mechanical loads in the aircraft’s structural elements. They include the structural elements connecting the aircraft’s wing to the fuselage, which main component is the ear-plug design. Under certain operation conditions of the product (aircraft) the stress field in the presented structures attains the unevenness of a high gradient.

Thus, the task is relevant, and its implementation is possible by the finite element method and employing the solution of the contact problem of a solid deformable body, by building a finite element model and introducing a contact joint between the node elements (fork, ear, bolt, nut).

The basis of the design is an empirical method for calculating the stress-strain state of a fixed plug-type “Ear-plug” type, which is employed as a test object in this work.

Firsanov V. V., Vo A. H., Tran N. D. Studying stiffened shells stress state by the refined theory with account for ribs elasticity and clamped edge. Trudy MAI, 2019, no 104,

The presented article considers the clamped edge pliability and ribs stiffness impact on the stress state of stiffened shells determined by the refined theory.

Computing was performed according to the approach based on the shell displacement expanding into polynomials, one degree higher than the classical theory of Kirchhoff-Love type, over the coordinate normal to the median surface. Differential equation of equilibrium and boundary conditions of the shell were obtained based on the 3D theory of elasticity and Lagrange variation principle. The formulated boundary problem was solved by an analytical method using the Laplace transform.

The calculation results revealed quickly damping additional stress states of the “boundary layer” type while calculations were performed by the refined theory. The values of longitudinal and circumferential shell stresses are substantially refined nearby the stress state distortion zones (in places of ribs fixing and clamped edge), while normal stresses values are of the same order with maximum values of the main (internal) stress.

The study revealed that the shell stresses reduced several times with account for the clamped edge pliability. An important result related to the additional stress state consists in the fact that with the ribs stiffness increases, the transverse normal stresses, neglected in the classical theory, increase substantially. The obtained results can be applied for the design and evaluation of the strength of aircraft stiffened shells.

Philatov V. I., Borukaeva A. O., Berdikov P. G. Distance measuring system employing modulation chaotic noise function. Trudy MAI, 2019, no 104,

The article discussed in detail the general characteristics of a distance measuring system or the range in which the transmitted signal is modulated by the chaotic noise. The distance measurement is performed by correlating the transmitted and received modulation signals. The modulating signal spectrum determines the function of this correlation dependence, and, hence, the system output, on the distance to the reflecting object. Particular attention is paid to the possibility of practical implementation of the filter, which limits the linear portion of the “system distance – output systems” characteristic for the system with noise modulation. Some new results that can be obtained are indicated. The article considers limitations of the method, and describes several types of noise-modulated systems. The successful operation of the system of one type is revealed. With a result of the described work, a system similar to the existing altimeters is proposed, but free from the ambiguity of reference inherent to the systems with periodic modulating function, devoid of systematic errors and allowing measure distances below several meters. This makes it particularly suitable for application as an altimeter in blind-landing systems. A method of analysis consideredin the article allows, within practicality, design the system with the desired “output – distance” ratio which can be installed further in the aircraft to determine the distance when performing takeoff and landing.

Kuznetsov V. S., Volkov A. S., Solodkov A. V., Slepov A. V. Studying OFMD with Amplitude-Phase Shift-keying Pulse-Amplitude Subcarrier Modulation and 10 bit/s/Hz spectral efficiency. Trudy MAI, 2019, no 104,

The presented work suggests a new modulation process, based on amplitude-phase modulation, with introduction of additional data transfer channel with amplitude modulation into quadrature to the transmitted signal with the amplitude-phase modulation. The OFDM system employing the suggested amplitude-phase amplitude-pulse modulation as a primary modulation method with frequency effectiveness of 10 bit/sample was considered.

Due to the quadrature modulation and demodulation scheme, with 8 amplitude levels of phase-shift keyed signal and 16 levels of a signal with amplitude-pulse modulation this method ensures frequency effectiveness in the output bandwidth up to the value of γPM-APM = 20 bit/s/Hz.

Additional advantages of this new proposed quadrature discrete modulation method consist in its high reliability while one of the modulation blocks failure, as well as its successful operation while phase inversion of the carrier recovered synchronization. Amplitude-phase modulation was selected as a prototype of the suggested modulation method.

A simulation model of a data transmission system with the given modulation method and OFDM technology was developed for studying the method of primary amplitude-phase amplitude-pulse modulation with selected effectiveness, surpassing the traditionally employed modulation methods in OFDM mode.

The simulation results allowed obtain experimental dependencies of the bit error caused by the signal to noise ratio conforming the analytical computation. The signal constellations of the amplitude-phase amplitude-pulse modulated signal, which shapes corresponded to the shape of the modulation type described by the author were obtained as well. The spectrum of the amplitude-phase amplitude-pulse modulated signal and OFDM signal were plotted. The spectrum effectiveness of the method, which also conformed with the theoretical computation, was obtained using the graph of the amplitude-phase amplitude-pulse modulated spectrum.

The required signal/noise ratio in the channel with additive Gauss white noise can be evaluated for the system functioning at the permissible error level by the dependence of the bit error probability, obtained while the system modelling. Thus, for the error level of 10–6 the required signal/noise energy ratio is 36.5 dB. The graph of power peak-factor distribution of the OFDM signal was obtained. The distribution appears the same as when the phase keying modulation used as a primary modulation. It is explained by the fact, that the main parameter affecting the distribution shape and peak-factor value is the number of subcarriers in the OFDM signal.

Gusev S. N., Sahno I. V., Khubbiev R. V. Evaluation technique for virtual objects on radar images formation quality. Trudy MAI, 2019, no 104,

The article proposes an approach to solving the problem of calibrating quality of synthetic aperture radar (SAR) employing test signal simulation system. Thus, the subject of the research is the quality evaluating methods of virtual objects formation on radar images in the interests of SAR calibration.

At present, a common approach to evaluating the bjects imitation quality on radar images does not exist. Thus, the goal of the work consists in developing alternative approaches to assessing the quality of virtual objects formation on radar images, which allow obtaining quantitative characteristics of similarity degree of virtual and real objects.

The proposed method is based on applying correlation analysis technique and the theory of signal detection, which allows drawing a comparison between two images. The radar images herewith are represented by matrices of independent random variables characterizing the values of the intensity and coordinates of the corresponding target marks on the radar image. A special feature of the proposed approach is the study of the statistical characteristics of differential radar images.

The result of the work is a method for evaluating the virtual objects formation quality on radar images, and analytical expressions for computing the following characteristics:- the correlation index of the reference and virtual radar images:

  • the mean-square error of the virtual object formation on radar images;

  • the probability of a virtual object creation, which is an integral indicator, characterizing the probability of achieving such similarity degree of real and virtual objects, under which they cannot be distinguished.

The developed method was approbated during a semi-natural simulation of the virtual objects formation process on the radar images. The simulation results, presented in the work, validated the method and the required quality of the predefined virtual object formation.

The proposed method can be used for:

  • SAR calibration at various stages of development and design;

  • transponders development with program signal generation;

  • feasibility demonstration of the development trends for the SAR methods and measures.

Semakov S. L. On one approach to the probabilistic estimation of a civilian aircraft safety landing. Trudy MAI, 2019, no 104,

The problem of probabilistic estimate of safe landing for a civilian aircraft is considered. As is known, for civilian aircrafts, multi-channel means of recording flight parameters (MMRFP) are established, and in the ground service of the airline there is a division engaged in decoding the records of MMRFP. If necessary, the entire flight can be decoded, but, as a rule, only the most important parts of the flight, including the landing, are deciphered. The following task is posed: after a real flight, relying on the MMRFP records, we have to analyze the implementation of the random landing process and we have to characterize the quality and, in particular, the degree of safety of this particular landing of the aircraft in question. As a rule, according to the MMRFP, the deviations of the flight parameters fr om their nominal values ​​at given times, such as the time of flight of the runway end, are estimated. However, often going beyond the individual restrictions set out in the Flight Manual of an aircraft not only does not create the prerequisites for an accident, but also, taking into account the whole situation, can reduce the probability of an undesirable event. Therefore, it is not individual deviations that are more important, but an integral indicator of the landing process, for example, the probability of a safe landing, by which one can objectively judge the quality of piloting (manual or automatic) and the degree of safety of the landing in general.

In this paper, an aircraft motion is described by an n-dimensional random process Υ(x)={Υ1(x),...,Υn(x)}T, where T is the transposition symbol, x is the flight distance counted from the moment the landing process is considered from a fixed point of the landing surface (or its continuation), Υ1(x) is a random process of changing the flight altitude. A safe landing is the event ZD consisting in that the component Υ1(x) reaches the zero level (the level of landing surface) for the first time at any moment x* from a given interval (x',x"), x0<x'<x" , and at this moment the condition (Υ2(x*),...,Υn(x*))∈D is fulfilled, wh ere D is the specified subset of Rn-1. A scheme is proposed that allows decoding the MMRFP record of a specific landing implementation a posteriori to assess the quality of an already perfect landing from the point of view of its safety, i.e. a posteriori estimate the probability of event ZD.

Vataeva E. Y. Dynamics modelling of the extremal control system operation with extremum memorization. Trudy MAI, 2019, no 104,

Landing is the most complicated and potentially dangerous operation mode of the aircraft. It is well known, that in the landing mode the aircraft behavior differs from its behavior in the other modes. It relates to its dynamic characteristics as well. The study of landing dynamics is characterized by complexity and specificity, associated with significant instability of the considered modes related to the essential changes in flight parameters. The main feature of the landing mode is the aircraft proximity to the Earth surface, and the need to fly at low speeds, implementing rather complex evolutions. The article considers the issue of dynamics modeling of nonlinear automatic control systems (ACS) in transient conditions. A system with extreme characteristics is selected as an object, namely the extremum seeking system with extremum memorization.

The main task of the extremal control system is the automatic maintenance of the optimal value of the regulating action, which ensures an extreme value of the coordinates, object parameters, or any indicator of the process efficiency during uncontrolled and unknown changes in the properties of the control object itself and its operating conditions.

It must be borne in mind that the interaction of the braking wheel with the surface along which it rolls is of an extreme character. The feature of the developed system is that the aircraft behavior on the left slope of the characteristic differs greatly from its behavior on the right slope. The left slope of the characteristic characterizes a stable movement of the system, while the right slope corresponds to an unstable state of the system. This article addresses the issue of developing an extremum seeking control (ESC) system with extremum memorization in “Matlab/Simulink”. A semi-natural system ECS was developed on the NI ELVIS – II platform in conjunction with the LabVIEW graphical programming language. This complex can be employed for studying and developing regulators for various braking systems.

Volkov S. S. An approach to solving the problem of personality identification by gas-discharge visualization method. Trudy MAI, 2019, no 104,

The article considers the approach to solving the identification problem by gas-discharge visualization (GDV) method. This approach is planned to be applied in aerospace branch for the purpose of prevention of industrial espionage and penetration to the classified objects.

This work purpose consists in demonstrating the unique possibilities of the gas-discharge visualisation method.

The work novelty consists in the fact that the approach to solving the problem of identification with the GDV method was not applied anywhere else, and was not considered. The interest to the personality identification in an aerospace complex is caused by the fact that many modern identification methods have shortages and can be falsified. In this connection, a necessity for searching for the new identification methods, one of which is represeted by the suggested approach. The hypothesis that the GDV-images possess the «identification cells» was put forward, and the images with the filter obtained in the process of shooting are constant and arenot subjected to changing. Thus, based on the identification determination they will be the reference, with which the images without the filter will be compared. The images without a filter are made while an employee authentication

The article presents the example of application of the proposed identification method in aggregate with the automated assessment system of the operator psychophysiological state (PPhS). The given example is interesting to that it allows perform simultaneous monitoring of health and readiness for professional activity, and, at the same time, to carry out personality identification of the aerospace complex employee

In consequence of the study, it was confirmed that the above said approach really allows identifying the personality. The obtained data confirms the put forward hypothesis. However, it is necessary to perform at least ten iterations for the higher purity of the experiment.

The author recommends apply the approach to the personality identification with the GDV method combined with the automated system for phsycophysiological state estimation. This will allow both ensure claasified information integrity, and perform monitoring of physical and phsycological health of all employees of aviation, rocket and space branches.

Nemychenkov G. I. Control of beams of trajectories of automation type stationary systems given discrete inaccurate measurements. Trudy MAI, 2019, no 104,

The article considers the problem of optimal control for deterministic discrete stationary automation-type systems under parametric uncertainty in the presence of discrete inaccurate measurements.

The discrete automation system (SAT) is described by recurrent equations and serves as a mathematical model of control devices in the form of a memory automation. On a continuous time period of the SAT operation a finite number its state changes occurs. At the switching moments, when the changes of the state occur, the system trajectory has jumps. The system maintains its state between switches. In contrast to the classical models of discrete systems [1, 2], changes in the states, occurring at specified (clock) moments of time, the SAT switching might be arbitrary, not predetermined by moments of time [3, 4]. The quality of one trajectory control of the system is estimated by the functional, which takes account of the switching costs. Selection of the number of switches and clock moments is one of the control resources and is a subject to optimization [5]. This does not exclude multiple switching at a fixed time [3]. Thus, the problem of optimal SAT synthesis generalizes the problem of the discrete controlled system control [1, 2].

The problems in which suboptimal beam control is optimal are of interest. The well-known results relate to the linear-quadratic problems where the linear systems control is evaluated by a quadratic quality functional. It is shown in [6] that the optimal control of the beam of trajectories of a continuous system coincides with the optimal control of one (isolated) trajectory coming from the geometric center of gravity of the set of possible initial states.

Generally speaking, the principle of separation is not fulfilled in the linear-quadratic problem of controlling the beams of the set of trajectories In the examples given in [7], the optimal control does not coincide with the optimal control for the trajectory coming from the geometric center of gravity of the set of possible initial states. The reason for this consists in the fact that the price function in the linear-quadratic control problem of non-stationary CAT is not quadratic. It is shown in [18] that for the linear-quadratic control problem of stationary CAT, the price function is piecewise quadratic. This circumstance allows prove the validity of the principle of separation (with some modification) [19].

Based on the sufficient conditions the algorithms of synthesis of suboptimal and conditional suboptimal control of beams of set trajectories are developed. The algorithm efficiency the is demonstrated by the academic example of a linear-quadratic problem.

Shipko V. V. Method and algorithms of inter-channeled gradient reconstruction of multi-spectral images in optical-electronic complexes of air and space reconnaissance. Trudy MAI, 2019, no 104,

The goal of the work consists in improving the accuracy of multispectral digital images reconstructing distorted by applicative interference due to the inter-channel redundancy property of multi-channel optic-electronic complexes of air and space reconnaissance.

The author proposed and studied a new method and algorithms for inter-channel gradient reconstruction of the information component of multispectral images distorted by the impulse and spatially extended applicative interference, based on the implementation of the inter-channel redundancy property.

The proposed method is based on the assumption of the approximate equality of gradients of the adjacent channels of multispectral images. The method consists of the two stages.

At the first stage, the spatial position of the interference in each component is estimated. For these purposes, an algorithm for inter-channel gradient detection of interference in each spectral channel based on a new principle of the inter-channel discrepancy between the gradients of individual spectral channels of a multispectral image, has been developed. At the second stage, an inter-channel gradient reconstruction of the spectral channels of the multispectral image is performed in the distorted sections according to one of the developed algorithms, based on the borrowing information on the gradients of the corresponding sections of undistorted channels.

As the results of the numerical and experimental studies demonstrated, the proposed method allows obtaining a higher detection and reconstruction accuracy of distorted image areas in comparison with existing processing methods. In this case, the computational costs of the developed algorithms allow processing color (3-channel) images in a time scale close to the real one.

Groshev A. V. Algorithmic improvement strategy for accuracy characteristics and information reliability of inertial satellite navigation systems withing unmanned aerial vehicles. Trudy MAI, 2019, no 104,

Nowadays information reliability improvement of inertial satellite navigation systems (ISNS) and competition in correction and guidance accuracy are the most significant tasks for developers of special types of advanced unmanned aerial vehicles (UAVs).

Non-redundant ISNSs for highly dynamical UAVs, tested in natural and semi-natural conditions, as well as with complexes of simulation and mathematical modelling, are the subject of research in the presented article.

The research objective is the development of the ideology and program-algorithm solutions for the accuracy and information reliability improvement of high-precision ISNS for UAVs, continuous true navigational information acquisition for the control system of highly dynamic UAVs in condition of unstable operation of the satellite navigation systems consumers, or and electronic countermeasures.

Strategy and effective program-algorithmic solutions for ISNS failure information identification and elimination of co-processing were developed based on SINS mathematical models, satellite navigation systems and electronic countermeasures systems consumer equipment scientific software of complex system, seminatural and development tests. Such a strategy and solutions improve the control stability, accuracy and information reliability of the system.

Errant information identification algorithms based on Kalman filter (KF) residuals, which are able to retain the characteristics of the system in varied operating conditions, and also the results of its tryout on the mathematical and simulation modeling systems are considered in the article. Approaches based on tolerance control using time-series model predictions or KF squared residuals normalized with RMS deviation of its moving unweighted average which is calculated with intervals by means of sliding window are suggested. The article enlightens an approach to the satellite navigation systems consumers equipment corrections after the “information shadow” for high accuracy systems, and presents the results of mathematical, simulation and semi-natural tests.

Correction methods for satellite navigation systems and electronic countermeasures systems consumer equipment after “information shadow” for high accuracy systems are presented.

The proposed methods and algorithms were used while ideology formation of the certain types of UAVs application.

Ivashova N. D., Mikhailin D. A., Chernyakova M. E., Shanygin S. V. Neural network solution of the operational planning task for unmanned aerial vehicles route flight and time setting for ground based objects observation employing the fuzzy logic while displaying these results on the computer screen prior to the start. Trudy MAI, 2019, no 104,

The article considers the possibility of neural network realization of operational planning of the route flight of the unmanned aerial vehicles (UAVs) while ground based objects observation, when the flight task requires correction due to the change of dynamic situation. It happens when either the observation quality of certain object appeared too low, or video information indicates the new objects occurrence, or observation of a number of of objects was untimely.

The number of ground based objects, coordinates of their position and their relative importance as well as the number of UAVs and their current coordinates at the given planning step are regarded as set in the formulated problem statement. The article demonstrates that the operation planning at each step consists of two operations. The first operation consists in determining the initial set of the most important objects of observation, and the second is assigning for each of them their “own” UAV.

The authors suggest the problem solution with the three layer neural networks of sequential distribution with sigmoidal activation function in the first two layers and relay function in the last layer. The article demonstrates that these neural networks training required a small number of examples. Employing special schemes for determining the number of the primary target and the number of the servicing UAV, the onboard program neural network complex was formed. This complex is capable of realizing the process of operational planning in the real time mode.

At the same time, the objects significance estimation representation in the form of the multiplicative convolution of partial criteria reduces the input signals number, and, hence, the neural network structure dimensionality. The structural diagram of the fuzzy logic expert system for the allowed search time determining, and detecting each of the objects of observation with account for the three factors: the growing risk of detection failure at the searching time increase; significant fuel consumption excess, as well as the time reduction to the flight termination.

The adaptive fuzzy logic expert system, determining the moment of observation termination depending on the current parameters of the dynamic situation, was formed to automate the process of continuing managing servicing of the next object of observation, while searching for it in the proper place.

Eremin E. O., Kharlamov G. Y. Instrumental photometric standard for onboard optoelectronic devices of near-Earth monitoring space systems. Trudy MAI, 2019, no 104,

The article introduces a notion of an instrumental photometric standard for onboard optoelectronic instruments and considers specifics of its forming. This standard employing allows evaluate energy characteristics of a particular onboard optoelectronic device in various background-signal conditions with a reference accuracy. The structure of the instrumental photometric standard application is based on employing classical methods of astronomical photometry and statistical processing of measurement results. The proposed method is similar to the satellite photometric observations processing, but the onboard optoelectronic device is evaluated by the photometric stars-standards, and not contrariwise. The article presents equations for energy units conversion between the in-system units and astronomical photometry units. Basic photometric and spectrophotometric catalogues that can be employed to develop the instrumental photometric standards of the onboard visible and infrared optoelectronic devices are considered (both for visual and infrared optical bands). Graphical representation of the reviewed star catalogs’ photometrical bands is presented. The methods of photometric measurements on digital frames from the onboard optoelectronic devices, namely the method of aperture photometry and method of PSF-photometry (Point Spread Function photometry) are briefly reviewed. The method of standard stars samples forming for developing the approximating models of the instrumental magnitudes for different background-signal conditions is presented. Applications of an instrumental photometric standard for onboard optoelectronic devices are the near-Earth space monitoring systems at the stages of flight tests and exploitation. Efficiency of algorithms of construction and employing implementations of the instrumental photometric standard for the onboard optoelectronic devices based on simulated and experimental data will be considered in the subsequent articles.

Mironenko V. V. Cutting-downs shaping on sheet parts employing a movable clamp. Trudy MAI, 2019, no 104,

The possibility of the defect of an «incomplete stamping» type is demonstrated on the example of the part with the standard cutting-down. This part has a standard cutting-down, and according to the regulatory document OST 1.52468-80 should be shaped without defects. Such defects occurrence leads to the manual refinement, and, hence, to the part cost value increase. The author proposes a scheme of shaping with the movable clamp application, allowing avoid the above said defect. The article demonstrates this scheme application for producing the parts with non-standard cutting-downs. It demonstrates also the scheme of shaping with the movable clamp, and describes the route of the part shaping to obtain the maximum effect from the suggested technology application. The author shows on the model parts that only the movable clamp application allows avoid the defects of “incomplete stamping” and “corrugation forming” type. The model parts were selected from the regulatory document OST 1.52468-80 zones, in which the part should come out with the defects. However, a movable clamp application for shaping allowed avoid defects such as “incomplete stamping” and “corrugation forming”.

For all three parts, a finite element analysis was performed with the PAM-STAMP 2G simulation program of the French ESI Group company. Actual tests with the INRTU experimental installation and the QFC1.2×3 industrial press were performed according to the simulation results.

The purpose of the article consists in improving the conventional technological process of producing the parts with the cutting-down element. The article solves the following tasks:

replacing the unstable forming method with a newer one:

  • elimination of «incomplete stamping» and «corrugation forming» defects while the cutting-downs formation;

  • expanding the possibilities of parts manufacturing with the cutting-downs through the non-standard cutting-downs application;

  • ensuring the cutting-down formation with specified sizes that do not require manual finishing.

As a result, a technology for cutting-downs shaping with a movable clamp has been found that allows stably producing of the flawless parts with both standard cutting-downs, and cutting-downs that go beyond the normative documentation recommendations. The technology is universal, and it can be employed at various aircraft-and machine building enterprises.

Lobastov I. A., Paleshkina Y. V., Alexeeva N. N., Paleshkin A. V. Selecting design parameters of the centrifugal test bench while quasi-static-oscillating loading of the test object with free oscillations of the system. Trudy MAI, 2019, no 104,

At present, rocket and space technology (RST) is developing at a rapid pace in all advanced countries. A huge amount of resources is invested in this promising sector. RST has a number of features. Its design cannot be duplicated, and it is almost impossible to repair it after the start of flight operation. The designed construction has to function at all operation stages. The loading factors determine the shape and internal structure of the structural elements and the structure as a whole, and loading analysis is an important, integral part of the rocket design of and space technology elements. Thence, a problem arises as recently as at the preliminary design stage on the possibility of application of the already existed experimental base of the space-rocket engineering designer for performing experimental developing in conditions close to the product natural operation conditions. According to the tasks set in the work, the calculation part was separated into three components. In the first part, a well-known mathematical model is used for the movement simulation of the descent vehicle in the atmosphere of the planet with different input angles along the ballistic trajectory. The data obtained while calculations served as an initial data for the second stage, namely, computing and selecting parameters of the centrifugal test bench to perform tests at quasi-static-oscillating loading with natural oscillations of the system. At this stage of the test simulation, the result represented the analysis and selection of the design parameters of the test bench, and the mode of testing under given conditions of functioning and operation of the product. At the third stage, based on the compiled algorithm, the calculation of the centrifugal drive power was performed, with account for the operating limitations for the selected stand operation mode.

With the result of the performed work based on mathematical models and computational algorithms, a software package was developed using MATLAB, allowing obtain at various initial data operational and energy parameters of the test bench for certain testing modes.

Kudinov I. A., Kholopov I. K., Khramov M. Y. Multispectral panoramic video images forming technology for aviation optical-electronic vision systems. Trudy MAI, 2019, no 104,

The article considers the video image forming technology according to the information from distributed multi-spectral cameras of the aviation panoramic optical-electronic vision system. It analyses the main problems of a panoramic frame stitching quality reduction while working with multi-spectral cameras. The article presents the geometric formulation of the problem and main analytical expressions describing the spherical panorama forming procedure without evaluating the point features of the scene, and searching matches between them using descriptors. A robust to shooting conditions algorithm for panorama image forming according to the results of preliminary photometric calibration of multispectral cameras with the special test-object and information on the angle orientation of the reference camera, obtained from the inertial micro-electromechanical sensor, was developed. One of the possible variants of the universal test-object realization for the multi-spectral cameras calibration is presented. The main operation modes of a panoramic vision system prototype with television and thermal cameras developed by the authors are considered including vision improving functions such as blending and contrasting according to Multiscale retinex algorithm, as well as information integration from the technical vision channels operating in various spectral areas. The article shows that computations parallelization using CUDA technology allows realizing vision improvement functions including information integration from multispectral sensors and overlapping additional signographic information for two independently controlled 1024 x 768 pixels regions of interest with a frequency not less than 30 Hz. The results of semi-natural experiments on the window of user interest display in the “transparent cabin” mode are presented.

Display of video information in the region of interest in accordance with the concept of “transparent cab” are presented.

Voskoboynikov M. A., Podstrigaev A. S., Davydov V. V. Modelling and evaluation of wind impacts on parachuted radio monitoring module. Trudy MAI, 2019, no 104,

The article presents the development and examples of the mathematical model application, which allows estimate the wind impact on the parachuted radio-monitoring module. The antenna beam direction of the radio-monitoring module depends on the parachute and carrier design, wind forces and atmosphere parameters. The developed model allows obtain the time dependences of angular deviation of the antenna beam from the vertical (Θ angle) at various wind impacts, as well as parachute and carrier parameters. These dependences allow estimate the view area of the radio monitoring module on the ground. The mathematical model assumes high rigidity of the parachute slings and canopy. This allows applying the Newton’s second law for rotational motion to prepare mathematical expressions. Simulation based on the obtained formulas was realized in MATLAB Simulink. The main advantage of MATLAB Simulink when solving this problem is the possibility of changing variable coefficients while integrating differential equations. The wind speed in the MATLAB Simulink model is set by signal generators. This allows obtaining the time dependences of the angle for a variety of wind impacts. As a result of modeling in MATLAB Simulink, the dependences of maximum and average deviation angles for the specified parachute and carrier parameters on the wind speed at various altitudes were obtained. Simulation results allowed estimating stability of the zone of vision position of the small-sized radio-monitoring module.

Chigrinets E. G., Verchenko A. V. CAD/CAM/CAE systems, OMV technologies and neural network based data analysis algorithms at the aviation industry enterprises. Trudy MAI, 2019, no 104,

In modern tough competition, aviation enterprises seek to maximize the capabilities computers application for products designing and manufacturing. To automatize these tasks, digital technologies such as CAD/CAM/CAE systems can be employed.

A technique for a 3D model of a helicopter dustproof device developing in the CAD system based on the coordinate measurement with account for real manufacturing deviations is presented.

The overview of milling technology of a helicopter part with the uneven hardness was performed. Optimization method of machining technology based on the finite element method with CAE implementation for the engineering analysis system is proposed. Computation results of unwanted deviations of the non-rigid thin-walled elements under the impact of the load direction were processed.

The problem of performing adaptive machining to program the milling of the detail contours on the CNC machine in case of virtual workpiece location was solved. The CNC-program correction by measuring the workpiece actual position on the machine table is proposed. The control program correction can be implemented as the result of solving the task of minimax, while searching such state of its position in space, so that the maximum allowance on the machined contour would be minimal. A mathematical model is developed, that unambiguously identifies the workpiece position on the machine table according to the measured coordinates of the three points. The developed algorithms of automatic search for the of the CNC-program correction to implement the principle of adaptive machining solution of the minimax problem. The program was created, and the method for the CNC-program designing for virtual workpiece locating on the CNC machine is developed. Experimental testing has confirmed efficiency of the developed technique

Manufacturing of the new aircrafts requires development and improvement of new materials and technologies, imposing ever-increasing demands for quality and operation reliability. Most carrying aircraft structures made of polymeric composites are machined to ensure the high quality holes providing reliable fixation and assembly of the composite structure (e.g., spars of the main and tail helicopter rotors blades). Delamination, which can reduce the structural integrity of the material, is the important technological problem occurring while fiber reinforced composite materials drilling. The tool geometry and machining conditions are the most important factors affecting the quality of the processed holes.

Using a series of experimental data that include the delamination sizes depending on the machining conditions, the database for the further modeling has been developed in a matrix form. The first attempt to build an empirical description of the sizes of delamination that depends on two design variables (cutting speed and drilling feed) was unsuccessful, probably, due to the nonlinearity, which is generic for the drilling process.

To overcome this difficulty we proposed and tested an approach, which is based on the the artificial neural networks (ANN) employing to predict the quality of the holes drilled in the titanium foil reinforced glass fiber epoxy-based plastics. ANN training was being conducted using an errors back-propagation algorithm. Testing of the prediction accuracy was shown that ANN can provide quality of size prediction that exceeds 97%.

The obtained results allow recommend the artificial neural network application to predict the size of the drilling holes delamination in GFRP. In the process of statistics accumulation the ANN are able to perform the self-training to produce the results based on the newly obtained information, thus, adequately predicting the quality of the machined holes.

Karpenko O. N., Kostin P. S. Method for dive characteristics evaluation of the attack aircraft. Trudy MAI, 2019, no 104,

The article considers the isssue of determining the aircraft dive characteristics based on simulation. To achieve the goal of the study, a software-modeling complex was developed, which allows evaluate the characteristics of a dive attack aircraft. To achieve the goal of the study, a software-modeling complex was developed, which allows evaluate the characteristics of a dive attack aircraft. All models and most of the blocks are implemented in the Matlab@Simulink software package.

With a view of performing simulation of the attack aircraft dive and pullout the aircraft control laws were developed. These control laws were formed in accordance with the requirements of the guidelines for the attack aircraft flight operation.

The time of the pullout time and altitude change while the pullout were determined by the simulation results at various flight modes. The simulation was performed with pitch angles from – 20 to – 60° with an interval of 10° and at velocities from 600 to 900 km / h with an interval of 50 km / h.°

A nomogram for determining the altitude loss while the pullout as a dependence from the values of airspeed, dive angle and normal overload at the end of pullout was plotted based on the simulation results.

The presented method of dive characteristics estimating allows reduce the time, financial and labor costs for the relevant tests of an aircraft.

Balakirev N. E., Nguyen H. D. Tonality recognition specifics in a speech flow. Trudy MAI, 2019, no 104,

The article discusses one of the possible approaches to solving the problem of recognizing specific speech aspects related to tonality, which occupies an important place in human communication. The degree of a particular state of tension is, above all, reflected not in the content of words, but in the way they are pronounced, which sometimes carries a different meaning regarding the content of words. Solution of such problem can be used in aviation technology, in particular, for automatic recognition of the emotional state onboard, for highlighting the emotional segments of speech in the records of flight recorders, as well as the speech of passengers of local and international flights. Tonality is of special key importance in the tonal languages of Southeast Asia, although it is of no little importance for European languages also, reflecting the character of the spoken phrase and introducing additional meaning into the content of the words and sentences being recognized. Anyhow, the tonality itself manifests itself identically, but in has its specifics in relation to the information content of a phoneme or a word. And it relates in the first place to the consideration of an object itself, bearing information about the tone. In contrast to the solution of the word sequence recognition problem, where the set of frequencies is a guide, the tonality recognition problem cannot rely on the generally accepted mathematical methods of wave processing and recognition. Considering the tonality recognition issues is, as a rule, beyond the scope of wide discussion in these methods, and the sphere suggestions for algorithmic solutions of this problem is considerably confined. Thus, the tonal component of the phoneme, that can be obtained by the special methods different from the conventional methods, is considered by the examples in the first place. The authors suggest the methods based on setting relations between the characteristic points and representation of these relations configuration in the form of matrix model.

In fact, such model is a qualitative tonality characteristic that does not depend on the amplitudes value, which allows compare different manifestations of tonality expressed in the loudness of pronunciation. The comparison itself assumes the presence of a qualitative measure, which allows reflecting the degree of difference of the considered phonemes in the speech flow.

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,

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.

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,

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,

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,

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. Cxpl is computed for both laminar and turbulent layers with account for the friction resistance coefficient Cxfr , coefficient of cylinder blunting resistance Cxbl and bottom pressure coefficient Cxbot :

Сxpl = Cxfr + Cxbl + Cxbot

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:


Сwклина = Cxзат + Cxтр + Cxдон + Cxклина


Konyukhov I. K. Analysis of “flying wing” scheme application at unmanned aerial vehicles of “air-to-surface” class. Trudy MAI, 2018, no 99,

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,

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,

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:

  1. Creating the frame of the selenodetic coordinate system with the axes reference to point reference points (light laser beacons) on the Moon (included in the “Luna-global” and “Luna-Resource” programs).

  2. Installing the new control light laser beacons with retroreflectors in the explored areas of the Moon (3-5 PCs or more, depending on the place of operation). It is necessary, that of the control beacons positions would be consistently affixed to the LRO lunar images, to obtain a topographic map of the Moon.

  3. Accommodation of the Lagrange points of opto-electronic instruments for continuous monitoring of the spacecraft on the lunar surface.

  4. Periodic control of the frame selenocentric coordinate system in its current state on a running light laser beacons (while polar-orbiting lunar satellites operation).

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,

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,

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:

QD = kT ⋅ µ ⋅ Fnz ⋅ (ρD/98066,5)n,

wh ere kТ = f (TН) – 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, –;

Fnz – a minimum area of an orifice throttle, m2;

pD – 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,

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,

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,

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,

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,

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,

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,

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,

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.

Kuzmin R. E. Phase locked loop of satellite communication systems receiving channels. Trudy MAI, 2018, no 99,

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,

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,

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,

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,

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,

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:

  • Automatic letters linking

  • Access authorization for observers

  • Provision of a customizable list of employees with the ability to control letters.

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,

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,

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,

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,

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 × 105.

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,

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,

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 

  1. The body performs a periodical reciprocating motion with a period equal to the period of a full turn of the point along the circle. The body moves during equal intervals of time in positive and negative directions. These time intervals of movements interlace with quiescence intervals of the body on horizontal plane.

  2. The body moves with periodic velocity. With that, during one cycle the body shifts in positive direction, changing twice the direction of its movement. Time intervals of motion in negative direction are separated from those in positive direction by quiescence intervals.

  3. The body moves non-periodically. The motion is of asymptotic nature, i.e., it approaches a certain limiting periodic mode of motion. In this limiting mode, the body moves in positive direction.

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,

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,

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,

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,

Determination of properties of inhomogeneous lines for use in various filters.
Is the rationale for the method of determining the matrix of idling and the equivalent circuit for an inhomogeneous segment of a line obtained from the uniform by deducting in one of the poles to study the properties of the current segment.
The equivalent circuit for the input resistance of this chetyrehpolozyj in idle in forward and reverse directions will represent the series connection of the cut of the uniform line length and paralelnogo circuit without losses. The appearance in the equivalent circuit with a negative capacitance and inductance from the physical point of view can be explained by considering a transition from segment a heterogeneous line to infinite to length non-uniform line and back.
Since all the resulting contain, as the longitudinal elements parallel to the contours without loss, we can assume that such segments inhomogeneous lines have filtering properties.Oscillations with a frequency close to ωП(in the vicinity of which is the «outrage» spectra), the load did not arrive, and for large misalignment from the resonant frequency pass through without isogeny, i.e. those segments of the inhomogeneous lines have the properties of band-limiting filters, and with a single locking strip in the vicinity of the resonance frequency with no spurious rejection bands; at multiple frequencies.
Thus, to build a narrow-band band-band-stop filter with a single band locking can be used approach to the calculation of resonator filters – the inclusion of heterogeneous cut lines on the passage, in which the formation of the desired characteristics of the working attenuation is due local reflections resulting from impedance changes in the coordinate.

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,

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,

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:

  1. For a T-13P fabric (100), a 20 mm hole is the limiting size when it is punctured. This required a significant load for the puncture. There was a snacking of the tissue between the piercing element and the edge of the hole at the bushing. This situation is caused by the impossibility of further compression of the filaments perpendicular to them and it becomes impossible to further expand the hole. When puncturing a hole 18 mm in diameter, all these troubles were absent. Thus, a hole with a diameter of 20 mm was prohibitive, therefore, we can confirm that the limiting value of the hole for puncturing is in the range of 18 to 20 mm.

  2. For a T-13P (100) fabric, holes of 6 mm or less do not create a stress concentration near the holes in the fiberglass material.

  3. The structures with punctured holes are about one and a half times stronger than those with holes drilled.

  4.  As the diameter of the pierced hole increases, the stress concentration increases.

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,

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,

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,

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,

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 kΣ = a1 kG + a2 kC + a3 kF .

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): a1 = 9, a2 = 3, a3 = 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.

Zareckiy M. V., Sidorenko A. S. Dynamic state of aviation products structures with weld junctions. Trudy MAI, 2018, no 98,

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,

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,

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,

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,

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,

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,

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,

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,

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,

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,

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,

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.

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,

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,

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,

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.

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,

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.

Makarenkova N. A. Controlling the kinetic moment of the solar sail by changing of the reflectivity of its surface. Trudy MAI, 2018, no 98,

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,

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.

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,

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:

  1.  The input data are the attributes of the applications, the characteristics of the flow of applications for each type of consumer (law of the distribution of time intervals between applications submitted).

  2.  As criteria for optimality, we can take the mathematical expectation of the execution time (service) of all applications, the total cost of servicing all applications.

  3. The restrictions are the value of available resources of the possible GDPS, the amount of RAM, the size of long-term memory, the load of the processor(s), the policy of allocating computing resources (a set of prohibitions and priorities for receiving, storing and issuing information to consumers), performance indicators like effective system performance, the aggregate information value of products.

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,

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.

Stetsenko N. S., Khokhlov A. V. Identification of Rabotnov nonlinear constitutive relationship on the data of polyethylene and polypropylene creep tests. Trudy MAI, 2018, no 103,

The paper presents calibration technique for the Rabotnov nonlinear (quasi-linear) constitutive equation is developed using a set of creep curves of the material under uni-axial loading. The constitutive equation describes rheonomic materials behavior and generalizes the linear integral relationship of viscoelasticity with an arbitrary creep function by introducing the second material function. We propose to construct isochronous creep curves by the test data, approximate them by a number of special families of functions depending on 4-7 parameters and sel ect the most suitable family (the one yielding the smallest value of the relative quadratic deviation from the experimental points). As a rule, such families of functions could be chosen, which permit the analytic inversion of the constitutive equation, which enable not to resort to an approximate treatment procedure and reduce the identification error. Next, a “basic” isochronous curve should be selected (its selection is related to the choice of the characteristic time scale for the test under study). A nonlinearity function is being found fr om it. Then, with account for the specific features of the experimental data, the type of the creep function approximation is selected, and its parameters are found (using the nonlinearity function obtained before). The advantages of the identification technique were considered compared to the conventional one. In particular, the procedure for quantitative estimation of the similarity condition fulfillment for experimental isochronous creep curves (the necessary condition for the relation applicability) was proposed.

The identification procedure was applied to polyethylene and polypropylene creep tests. High-density polyethylene is widely used for manufacturing of water and gas supply pipes and other products. Thus, the study of their mechanical characteristics and their behavior modeling is of great interest. Verification of the obtained material functions was performed using the creep curves, that were not used for the identification procedure, stress-strain curves with constant rate and multi-step creep tests. It was shown, that the technique developed herein describes the experimental data well.

Ovdienko M. A. Development of a calculation model for planing seaplane equipped with automatically operated interceptors. Trudy MAI, 2018, no 103,

The presented work is dedicated to the development of high-speed vessels equipped with automatically controlled hydrodynamic interceptors to improve their hydrodynamic characteristics and seaworthiness.

The hydrodynamic interceptor is a small plate, being mounted transversely to the flow, near the aft cut or planing step of the gliding vessel. Due to the flow deceleration afore them, the area of increased pressure formed created, which leads to the total lift force increase and the displacement of its application point towards the interceptor. Thus, the interceptor can operate as a hydrodynamic mechanization to control the trim and roll angles. The interceptor minimal effort is required to move the due to the orthogonal position of the plates’ direction extension and the forces acting on it. It allows developing high-frequency control systems based on interceptors.

The author proposes to install controlled hydrodynamic interceptors on stern of seaplane forebody hull. It is possible to achieve optimum trim angles, which ensure minimum resistance, by controlling interceptors. It is also possible to fend off the oscillations and overloads acting on the seaplane during the planing on waves by controlling interceptors in the automatic mode. To verify this proposal, a mathematical model of the seaplane planing in conditions of smooth water, as well as regular and irregular waves was developed. The mathematical model is based on the plane cross sections method and accounts for the presence of hydrodynamic interceptors. Besides, this model allows simulating the operation of an aerodynamic pitch-rate damper, which is used as an elevator.

Computations were performed for a seaplane with a take-off mass of 37 tons, the of forebody width near the stern of 2.1 m, and a take-off speed of 52 m/s. Computations of planing on calm water confirmed the assumption on the possibility of the effective trim angle control, and thus ensure a minimum drag force. It was found that uncontrolled interceptor could lead to self-oscillations, but the automatic control system introduction completely eliminated the possible instability. Thus, the automatically controlled hydrodynamic interceptors can be considered as a tool of the seaplane steady planing boundaries expansion.

The seaplane planing dynamics in conditions of regular waves were simulated at the wavelength of 50 m and a wave height of 0.8 m. The computation results revealed that the hydrodynamic interceptors control system allowed reducing by several times the amplitude of the seaplane oscillations in the trim angle and in the vertical plane. Automatically controlled interceptors are most effective while joint operation with aerodynamic pitch dampener.

The performed studies confirmed the assumption put forward. Automatically controlled hydrodynamic interceptors application can be recommended for hydrodynamic and seaworthiness characteristics enhancing of the conventional and prospective seaplanes.

Sorokin F. D., Zhang H. ., Popov V. V., Ivannikov V. V. Roller-bearing energy model experimental verification for aircraft engines supporting nodes modeling. Part 1. Roller-bearing loading by radial force and lateral moment on the special test bench, preventing the rings bending. Trudy MAI, 2018, no 103,

A wide range of scientific contributions discloses various aspects of roller-bearings parts behavior and interaction [1-15]. De Mul [9] developed relatively simple but at the same time quite efficient model where each rolling element was discretized with a set of thin slices and the nonlinear static equations were constructed afterwards. The paper [10] significantly advances the de Mul’s ideas. It revealed that the use of energy conservation approach instead of equilibrium equations derivation was much more convenient. Once the deformation energy of the roller is constructed, the forces acting onto the rolling element (along with the corresponding tangent operators) are easily restored from the potential as the first order (or the second order for the tangent operators case) derivatives.

To verify the energy model of the roller bearing, a full-scale experiment was performed on the universal Zwick/Roell Z100 test machine. Roller bearing of the 12309KM type, fixed in a special device that secured the outer ring, was loaded by a radial force and bend moment through a rigid bar. Deformations of the parts, used for the bearing fastening and loading, were preliminary estimated by calculation using the FEM. The experimental data was processed by the of least squares method to approximate it by analytical relationships. Comparison of the experimental data with the numerical results obtained from the previously developed energy model revealed their good agreement. From the study, we can conclude that the energy model of the roller-bearing is rather accurate.

Firsanov V. V., Doan Q. H. The study of the stress-strain state of symmetrical rectangular plates of arbitrary geometry based on the refined theory. Trudy MAI, 2018, no 103,

The article presents a refined theory of the stress-strain state calculating of rectangular plates symmetric in respect to the plane and arbitrary geometry in the longitudinal direction. Equations of the plate state are described by the relationships in the three-dimensional theory of elasticity. The required displacements of the plate are decomposed into two polynomials in a coordinate, normal to the plate surface, two degrees higher than that in the classical theory of the Kirghoff-Love type.

The system of basic equations of the refined theory and the corresponding boundary conditions were obtained by the variation Lagrange principle.

One of the distinguishing features of the proposed refined theory consists in employing direct integration of the equilibrium equations of the three-dimensional elasticity theory to determine the transverse normal and tangential stresses.

For isotropic rectangular plate of various thicknesses, a system of differential equations of equilibrium displacements with various coefficients, containing additional terms, accounting for the effect of a thickness change on the stress-strain state of the plate was obtained by the Levy method.

To solve this boundary value problem, the finite different method was employed. An example of the stress state computing of a rectangular plate with a thickness varying according to linear and parabolic laws was investigated. A comparison between the results obtained by the refined and classical theories was performed. It was established, that when studying the stress state in the zones of its distortion (joints, local stress zones, etc.), a refined theory should be used, since the additional corresponding stresses were of the same order as the values of the ground stress state.

In this article, the basic equations of the refined theory for the plate were obtained using the Lagrange variation principle and expansion of the desired displacements in thickness. This technique allows account for both the thin plates, and the plates with average thickness. As an example, the calculation of stress-strain state for a rectangular isotropic plate with variable thickness under the action of a distributed load is considered. The comparison of the strain-stress state of the plate computing according to the refined and classic theories is presented.

Zotov A. A., Kolpakov A. M., Volkov A. V. Algorithm for constructing a 3D model of a three-layer rotation shell with cone-shaped cells of the filler and variable shape forming. Trudy MAI, 2018, no 103,

Assigned the task of designing and manufacturing three – layer rotation shells with filler from conical cells and variable forming. The long-term operating experience of various technical objects made with the use of three-layer bags has shown their high efficiency due to the fact that, with low weight, they have high specific strength and rigidity. Their disadvantages include: low impact strength, complexity with the removal of condensate, low shear strength, the complexity of manufacturing. Traditional techniques for combining filler with bearing layers in the form of gluing or spot welding have low reliability, it is difficult to control the quality of joints. New technologies for manufacturing these structures from high-strength reinforced composite materials (glass, carbon plastic) and wide possibilities for optimizing their geometrical parameters make it possible to achieve higher strength characteristics of the aggregate for transverse compression, longitudinal shear and bending. Nevertheless, the problems of condensate removal, reducing the complexity of manufacturing, ensuring the reliability of the connection of the aggregate with the support layers, as well as the complexity of the construction of structures with variable geometric configuration make us look for new solutions.

This one shows the possibilities of using three-layer structures with a filler in the form of staggered cone-shaped cells made using 3D printing, which, in our opinion, largely avoid the above disadvantages.

The proposed regular structure and form of the elements of the aggregate makes it possible to carry out in one operation the construction of a complex configuration, providing ways to remove condensate, reliability of connection with the outer layers, having high thermal and sound insulating properties. A mathematical model has been developed and a demonstration model manufacturing algorithm has been implemented. CAD – model built according to the results of the calculation of the parameters of the shell and its placeholder.

Samples are made by FDM-technology. The presented designs are offered for use in aviation, aerospace, automobile, engineering, as well as in the production of refrigeration and cryogenic devices.

Amir'yants G. A., Malyutin V. A. On experimental determination of aircraft structures stiffness characteristics. Trudy MAI, 2018, no 103,

The competitive air materiel development is impossible without permanent improvement of methods for the aircraft stiffness characteristics studies, as well as their elastically similar and “rigid” aerodynamic models. The goal of the work consists in increasing the efficiency, informativity and precision of the stiffness characteristics study.

The article presents the results of studies aimed at improving the system of the stiffness characteristics experimental determination of full-scaled air materiel objects and their aeroelastic models. It presents a brief description of some basic elements of the system, in particular, the robotic test bench for determining stiffness characteristics, multi-channel data acquisition system, and automated loading system.

The results of experimental studies using the above said technical means are presented. For example, using the automated loading system and data acquisition system, the stiffness of fastening elements of the aerodynamic model in the wind tunnel working section was determined. The measured stiffness parameters were used in the computational scheme of the model in the ARGON software package, on which basis the aerodynamic loads were computed. The robotic test bench application for stiffness characteristics determination while determining the beam stiffness characteristics, and influence coefficients matrix allowed quickly and efficiently performing the stiffness tests of the elastically scaled model frame.

Some examples of ARAMIS stereophotogrammetrical system application for measuring spatial movements are presented. The abilities of this system are illustrated by its application in the international AFLoNext project of the Seventh Framework European programme. Quickly obtained data helped to compose a quantitative representation of the mutual movements of the engine nacelle, pylon and wing compartment. Another example of the ARAMIS application system is the of displacements measurement of the high aspect ratio wing in the wind tunnel flow.

The developed and improved system is one of the main elements of a multidisciplinary approach to the design of advanced air materiel, safe in terms of aeroelasticity and strength, and perfect in weight efficiency, aerodynamic and tactical-technical characteristics.

Azarov Y. A., Garifullin M. F., Chernovolov R. A. Evaluation of dynamic-scale models loading while buffeting study. Trudy MAI, 2018, no 103,

The presented work considers the specifics of the selection procedure of loads, acting on the dynamic-scale model (DSM), while testing in wind tunnels (WT) at various Mach and Reynolds numbers.

The article presents the procedure of aerodynamic loads refining, acting on DSM, based on “rigid” aerodynamic models’ WT testing. Based on dynamic pressure measurements in certain points of the rigid model, distributed aerodynamic loads for cross sections, normal to the DSM wing stiffness axis, can be determined. The information on linear and rotational forces, acting on cross sections is employed while the DSM design, ensuring the structural strength with the required safety coefficient.

Recommendations for computing distributed loads acting on the DSM and determining safety margins (the safety factor required for the testings equals to four) which fulfillment is necessary while th model design and fabrication, are given.

The stages which execution will allow perform the studies in WT are listed. The goals, objectives, features, problems and advantages of the DSM studies at natural Re numbers are formulated. The DSM design and manufacture specifics using various structural-power circuits made from modern materials and using modern technologies are demonstrated.

Some problems of ensuring the required Re numbers in studies of the phenomena of unsteady aeroelasticity in WT are considered. The difference between conducting an experiment with rigid aerodynamic models and DSM, as well as with full models and semi-models is shown.

Belyavskiy A. E., Sorokin A. E., Strogonova L. В., Shangin I. A. Heat accumulating processes selection for spacecraft thermal conditions ensuring systems. Trudy MAI, 2018, no 103,

In some cases, it is possible to employ the reversible processes, accompanied by endothermic effects in phase or chemical transformations of working bodies, for heat absorption, released from the energy sources onboard the spacecraft.

With the cyclic energy sources long-term operation, the most effective trend is application of such reversible endothermic melting processes, which are accompanied by the heat absorption at the interface between the liquid and solid phases of the working substance.

The article considers the issues of heat accumulators’ application in the thermal conditions ensuring systems (TCES) to ensure a spacecraft rational thermal state, including habitable bays. It is necessary for the crew medico-technical life support, and the spacecraft TCES weight reduction while the radiator-emitter design on average integral rather than maximum thermal loading when the heat accumulator introduction into the system.

The given dependences of volume and heat-mass characteristics of different processes and concepts of heat storage allow evaluate them from the viewpoint of the efficiency of the heat accumulator application in the spacecraft. It is shown, that the most effective and rational in the thermal respect are the phase-transition melting-solidification processes, thermochemical reactions and sorption reactions.

The successful solution of the space exploration problems requires improvement of the conventional and development of new ways and means of absorbing and diverting the energy dissipated by the equipment. These include the heat storage materials and devices on their basis, absorbing the energy dissipated by consumers in cyclic switching modes

The article deals with the characteristics of heat storage devices and processes occurring while changing the aggregate state of working bodies, namely, the phase transition materials with the required temperature of solid-to-liquid transition and back, their difference from traditional systems. The choice of the type of phase-transition processes from the viewpoint of their prospects for application in the spacecraft the system for thermal regime is justified.

A new trend of the thermal accumulators improvement is indicated, namely, application of composite form-stable phase-transition heat-accumulating materials that retain their shape during the working fluid transition from the solid state to the liquid state and back. This type of heat accumulators do not require sealing of the volume of phase-transition heat-accumulating materials, but it is necessary to ensure reliable mechanical and thermal connection with the structure on which the energy sources are installed.

The required thermal conditions provision of the onboard equipment is a complex and important problem of creating effective thermal control systems. Largely, this is facilitated by the development of heat storage systems for application in complex thermal control systems for further development of the heat storage devices such as heat accumulators.

Erkov A. P., Dudchenko A. A. On the issue of variable stiffness plates stability. Trudy MAI, 2018, no 103,

The article considers the problem of stability of the three types of variable stiffness plates: with the thickness stepped changing, thickness continuous linear changing, and with thickness combined changing (with the areas of both constant and continuously variable thickness). The plates are loaded with a compressive force, uniformly distributed over the two opposite edges. The force is applied in the median plane of plates. The boundary conditions are as follows: hinged joints over all four sides of the plate. Plates from isotropic materials and from laminated composites were considered. Three types of plates from isotropic material, and the plate from laminated composite with the stepped thickness changing were considered.

To study the stability of plates of variable stiffness the Ritz method was used. Analytical calculations were performed with the Maple math package. It was assumed that before plates were buckled, the stresses were in the elastic zone and were not exposed to destruction.

The results of analytical calculations were compared with the results obtained by the finite element method (MSC.Nastran / MSC.Patran). For each type of plate, three geometry options were calculated, and for the plate made of laminated composite material, three options for layups were considered additionally. In the case of an isotropic material, the maximum error compared with the results obtained in MSC.Nastran / MSC.Patran was not more than 7%. In the case of laminated composite plate, the error was not more than 9%.

In general, the accuracy of the applied method depends on two main factors:

  1. The correctness of the approximating function of the deflection. The approximating function should satisfy the geometrical boundary conditions;

  2. The number of the series terms accounted for. The convergence of the problem, in most cases, is the better the more series terms are accounted for.

The results of the work can be employed in the design of thin-walled structures, namely, to evaluate the stability of the thin-walled plates in areas of varying thickness.

Bezuevskii A. V., Ishmuratov F. Z. Aero-strength studies of a large aspect ratio strut-braced wing. Trudy MAI, 2018, no 103,

It is believed in many works that by now the aircraft classical scheme is almost brought to perfection, and the probability of new significant breakthroughs is minimal. However, today many other classes of the structures, inferior to the classical scheme by a number of parameters, have significantly larger range of possible basic and parametric improvements. One of these classes of structures is the aircraft with a large aspect ratio wing of a closed structure employing different struts options. The article provides an overview of publications on the study of of such constructions application. In particular, the authors consider the works with different variants of strut-braced wings, as well as the impact of the strut parameters on the aeroelasticity characteristics.

The effect of the strut on the aeroelasticity characteristics and weight efficiency for an aircraft with a large aspect ratio wing was studied. According to the parametric calculations results, the six flight cases of loading with positive and negative overload were found, which determined the strength of the wing. By the terms of strength, the wing box construction parameters for the aircraft without strut and with strut were determined in these calculated cases. The analysis of the obtained structures revealed that the wing box mass of the strut-braced wing is 11% less.

The comparative computational studies of the aeroelasticity characteristics of the obtained structures were performed. It is shown that the velocity head of the determining form of the flutter and the aileron reverse in roll control is 8% — 10% higher for the case of a wing with a strut.

Parametric studies of this model were performed. The optimal position of the strut on the wing chord is the trailing edge of the wing box. This allows win up to 2% of the wing box weight, and increase slightly the efficiency of the aileron and critical speed of the flutter. The wing kink is the most successful position of the strut in terms of the wingspan for this computational model. Also, it is worth noting note that the base stiffness of the strut 2 times increase would be optimal for this model. In this case, the structural weight of the wing box can be further reduced by 6%, and the aileron efficiency and the critical speed of the flutter slightly increased.

This approach application allowed reducing the model wing box weight by 17% without the aeroelasticity characteristics deterioration.

Kizeev I. S., Kozhemyako P. G., Ezrokhi Y. A. Computational and experimental study of air bleeding from the compressor intermediate stage effect on its characteristics. Trudy MAI, 2018, no 103,

Recently in connection with the studies of three-stream schemes of adaptive cycle engines the fan with air bleeding is considered as a basic part of three-stream adaptive engines. The values of such bleedings herewith can reach 15-20 % and more. Under such conditions, this pressuring element representation as a set of two compressor stages (the first – from the inlet to the bleeding point, the second – from the bleeding point to the outlet), with their own characteristics independent from the bleeding value, may lead to significant errors in determining integral characteristics of a power plant with a three-stream engine. In this connection, the problem of adequate characteristics setting of such adaptive fan acquires considerable importance.

The article presents the results of a compressors characteristics behavior changing estimation as a result of the air bleeding from an intermediate stage. Physical bases of the air bleeding effect on vane machines characteristics are presented as well.

Two compressors with different numbers of stages are considered: the three-stage compressor with air bleeding of 0 to 15% from behind the first or second stage (relative to the air consumption at the compressor inlet), and the six-stage with compressor with air bleeding of 0 to 10% from behind the third stage.

The obtained results of numerical computation and experimental data revealed that the additional air bleeding at maximum frequencies did not lead to the pressure line shift of a group of stages to the bleeding point. However, the pressure lines of the stages beyond the bleeding point were being shifted to the right and downward with the increase in the bleed air. At the lower rotation frequencies, the additional air bleeding did not lead to the pressure line shift for the first group, but it led to the significant shift of the pressure line to the right and upward for the second group.

This stratification of the pressure lines of the second group, following the bleeding point, can be explained as follows. While tapping a part of propellant from the multistage compressor airflow duct the operating point shifts right and downward (or downward in case of vertical branch) on the pressure line of the characteristic of the first group of stages by the lower values of pressure ratio, ensuring lower temperature levels of the air fed to the inlet of the second group of stages. This leads to the operating point shift on characteristic of the second group towards the larger reduced values of air consumption. Besides, the impact of non-uniform field of parameters at the inlet of this group of stages, appeared due to the air bleeding at the peripheral area of the blades, leads to the operating point shift in the same direction.

Baklanov A. V., Makarova G. F., Vasil'ev A. A., Nuzhdin A. A. The flame tube head perforated cowl impact on the main characteristics of the gas turbine engine combustion chamber. Trudy MAI, 2018, no 103,

The combustion chamber main parameters are the pressure losses, the unevenness of the temperature field in the outlet, and ecological characteristics. While the combustion chamber refinement for specific parameters it is rational to introduce changes in the design, and impact thereby the processes occurred in it. Very often, to reduce the flame tube resistance the designers resort to installing the perforated cowl, which reduces the frontal impact and distributes the air to the outer and inner cavities between the hull and the flame tube, ensuring minimal pressure losses. The presented article considers the impact of the flame tube head perforated cowl installation on the changes of the indicated parameters. The design of the perforated cowl is considered and the apertures number and diameter as well as the cowl fillet radius are listed. The structure of the test bench installation, with which the combustion chamber section was tested, as well as regimes at which these tests were performed, are presented. The results were obtained for the section with the cowl and without it. The analysis was performed, which results allowed drawing inferences on the necessity of the flame tube head header cowl in the full-scale combustion chamber. The results of the experiments revealed also that the flame tube head header cowl installing did not deteriorate the hydraulic losses in the combustion chamber, but appeared to be highly effective in terms of temperature reduction in the flow core at the section outlet.

The cowl installation leads to the air redistribution in such a way that its consumption in the burning area increases and leads to the temperature reduction in the flow core. The temperature reduction in the burning zone was obligatory affected the nitrogen oxides (NOx) reduction. The cowl did not affect the combustion efficiency, and the carbon oxides concentration in the combustion products increased herewith.

Gimavied A. G., Bukin V. A., Gareev A. M., Greshnyakov P. I., Kutuev S. S. Turboprop rotation frequency stabilization while its testing together with water brake. Trudy MAI, 2018, no 103,

While a turboprop design and operation a necessity occurs to determine their developed power and compressor gas-dynamic stability margin. Depending on the engine power water brake, electric and other installations are employed. However, water brake which shaft was connected to the turbo-compressor shaft through the clutch, was traditionally employed for the powerful engines. Disturbances from the water brake side in the form of water pressure (consumption) oscillations often occur while the engine testing. These disturbances lead to its rotor rotation frequency oscillations, which do not allow accurate determining the engine power or the compressor stability margin. The available information on stability provision of the engine rotation frequency while its testing on hydraulic braking installation, is insufficient. The article presents results of theoretical and experimental studies of speed oscillations of the turboprop engine rotor connected with the water brake. It is shown that in the engine-water brake system, the torque oscillations are excited by the frequencies:

– rotary frequency of 140 Hz;

– resonance of the water brake frame with the engine of 14.5...15.5 Hz;

– fluctuations of water in the water brake supply pipes of 3...5 Hz;

– the processes in the water brake rotating disk cavities and the of the test bench hydro mechanical engine speed regulator functioning of 0.15 ... 0.30 Hz.

Oscillations of the engine rotor speed occur in the low frequency range of 0.15...0.30 Hz due to its inertia. From all measures of the engine rotor speed stabilization, the best result was achieved by employing hydraulic dampers for pressure fluctuations at the inlets of water brake throttle valves. It ensured the amplitude of the engine rotor rotation frequency oscillations at 15...25 rpm at maximum mode, and the joint point of operation of the engine with water brakes. However, when determining the compressor gas-dynamic stability margin, an oscillatory process is observed, slightly exceeding the permissible amplitude values. Further turboprop engine rotor speed stabilization at this water brake installation, at which the compressor gas-dynamic stability margin determining is possible, can be performed by improving its test bench system for engine speed automatic regulation.

Barkova M. E. The satellite for utilization of space debris in near-earth space. Trudy MAI, 2018, no 103,

The main problem of article is creation of the spacecraft project for space debris utilization.

The purpose of the presented work consists in developing the concept and design of spacecraft, which will allow space debris reprocessing into fuel.

The relevance of this work consists in the near-earth space clarification from space debris by their reprocessing into fuel.

The main shortcomings of the existing projects of technical devices are large space debris crushing that leads to the smaller fragments formation.

The article suggests employing the concept of pseudo-liquid fuel creation. Pseudo-liquid fuel is the fuel obtained from the fine metallized powder in the gas environment. The spacecraft consists of a trap for space debris gathering, and a system for its utilization by which the space debris are reprocessed into the pseudo-liquid fuel.

The obtained results can be applied while the spacecraft design and operation.

The author comes to a conclusion, that the space debris reprocessing into the pseudo-liquid fuel is the most expedient, since this type of space debris utilization is waste-free.

The author’s unconditional merit is creation of the invention named “The spacecraft for the space debris utilization”, as well as the spacecraft operation design.

The prospect of further developments in this area consists in upgrading the system for the space debris recycling to reduce costs for the project, the spacecraft anti-shock body and its fan-shaped solar collector refining to avoid damaging while space debris collecting and the spacecraft project improvement for future realization.

Larina E. V., Tsipenko A. V., Afanas’ev A. A., Kryukov I. A. Turbulent 3D simulation code application to the pressure “hysteresis” analysis in the gas ejector vacuum chamber. Trudy MAI, 2018, no 103,

While studying operation of the supersonic gas ejector as a vacuum pump, special attention was paid to the so-called “hysteresis” observed in the dependence of the pressure in the vacuum chamber on the working gas pressure. The “hysteresis curve” occurs during the ejector start-stop, and oscillatory flow mode, undesirable at the unit operation, is observed herewith. In this regard, a series of numerical experiments on the oscillatory flow mode modelling was performed, and experimental data on the gas ejector operation was analyzed.

The simulation presented in the article was being performed employing the scheme of the increased order of accuracy and a three-parameter k-ε-μt turbulence model. Simulation of the flow with the uniform shear was performed in the simplified and 3D formulation. Collating with the other models was made.

Simulation of a plane submerged jet in the boundary layer approximation was made. A good agreement with experimental data on the averaged flow velocity was obtained.

A simulation of the supersonic overexpanded jet in a three-dimensional formulation was performed. The Pitot pressure at the jet axis was collated with the experiment and other models. The qualitative conformity with the experiment was obtained.

The numerical simulation using the k-ε-μt turbulence model dempnstrated that the “hysteresis” at the ejector start-stop is associated with a non-stationary parameter changes during the ejector start-stop. Thus, the ejector channel and the vacuum chamber parameters will be determined unambiguously under the steady-state boundary conditions. However, when real-life installations operation, the time required to reach the optimum mode at the smooth pressure increase is noticeably longer, than with a first sharp coming to overestimated parameters and then a small smooth throttling of the working gas pressure. The hysteresis loop reflects just this process.

The transient mode with low-frequency pulsations is necessary for the turbulence model verification. These mode predictions are important for the ejector optimal operation. Thus, a 1D self-excited oscillation model should be developed in future.

The work was financially supported by the RFBR grant No. 16-38-60185.

Us N. A., Avershin A. A. Mathematical model of the mono-bloсk ring gyroscope optical scheme Mathematical model of the optical scheme of the ring monoblock gyroscope. Trudy MAI, 2018, no 103,

Creation of NINS is one of the priority trends of domestic and foreign instrument making. High requirements for accuracy, availability, continuity and functioning reliability at various operating modes of mobile objects are specified to them. Ensuring implementation of these requirements at the present stage of development of technology is possible through application of laser gyroscopes as sensitive elements of inertial navigation. The presented research considers the new segment of laser gyroscopes – a ring monoblock gyroscope with the semiconductor laser diode (RMG with SLD) incorporating the advantages of the known gas ring laser gyroscopes (RLG) and fiber-optical gyroscopes (FOG). Applications of the new sensor of angular speeds like RMG with SLD as the NINS sensitive element allows simplify the design, adjustment and production technology, as well as vary precision parameters of the object modifications due to the mono-block geometry scaling and controlling the radiation mode of the laser diode. All this makes the task of analysis of the structure and processes, occurring in RMG optical scheme with SLD, with intent for further reliability enhancement of the navigation system output characteristics. The article presents and studies mathematical models of the basic structural and technological RMG solution and a model with increased quality factor, differing by the inclusion of optical resonators with high quality factors of a Fabri-Perot type. Mathematical models were realized using vector-matrix apparatus, which base is the ABCD matrix law. The algorithm for quality factor computing of the RMG optical scheme with open optical channels was developed.

The modeling results of the triangular optical scheme of two structural and technological solutions for optical channels lengths of 50, 100, 150 and 200 mm were analyzed, and rational RMG design options were systematized.

Surovtsev P. Y., Suslin A. S. Correlation-difference algorithm for aerial objects detection observed against non-uniform sky background. Trudy MAI, 2018, no 103,

The aircraft optoelectronic target detection systems employ algorithms based on brightness analysis. The target detection criterion is the of brightness threshold surpassing But there is a problem of false alarm caused by these algorithms due to the complex (e.g. cloudy sky) background.

This problem is solved applying the algorithms based on the frame subtracting called the difference algorithms. The criterion of target detection in this algorithm is the difference image with a non-zero signal. The difference algorithm can not be implemented in aircraft optoelectronic system without modification.

Thus, the goal of this work consists in developing an improved difference algorithm for the airborne optoelectronic system. The article proposes a correlation-difference detection algorithm. This algorithm allows apply difference algorithm for such airborne optoelectronic systems as FLIR.

The algorithm consists of two parts:

  1. Analysis of the inter-frame shift and its compensation (correlation algorithm);

  2. Subtract frames and target detection (difference algorithm).

In this work a semi-natural simulation of an airborne electro-optical target detection system against a complex background was performed. For the simulation FLIR with 50 Hz work frequency and 90 degrees field of view was used.

Thus, the algorithm allowed detect the target against the cloudy background and with displacement of the line of sight between the two frames in elevation of 45″ and azimuth of 31″.

In summary:

– The semi-natural simulation experiment revealed that the proposed correlation-difference algorithm can detect a target against cloudy background without false alarm;

– The proposed algorithm can be applied for optoelectronic system jitter compensation caused by vibrations of moving / stationary vehicle.

Kolesnikov S. Y., Skornyakova N. M. Comparing various types of tracers in particle imaging velocimetry method. Trudy MAI, 2018, no 103,

The presented work is devoted to studying measurements dependence, obtained by the particle imaging velocimetry (PIV) on the type of the employed tracers. The PIV is used for velocity measuring in the selected stream 2D section or its 3D volume while hydro- or aerodynamic experiments.

The accuracy of the flow parameters determining depends on the reflective particles, serving as speed determining markers. Their images represent the reference points for particles migration computing. Certain requirements are imposed on markers: they should be rather large so that they could be distinguished on the image, and, at the same time, they should be small enough and light to follow a stream accurately.

Several types of the tracer particles are employed in PIV experiments. The experiment was performed with applying three types of tracers: polyamide particles, hollow glass spheres and aluminum particles. The stream under study was created by the laboratory chemical mixer rotation in a water volume to which the observing markers were added. The whirlwinds fields of speeds in liquid for a nozzle of the «cross» mixer type were built Velocity measurements were performed separately for each tracer type, and fields of displacement vectors were constructed for the same rotation mode of the mixer.

The results of the experiment were analyzed regarding compliance of fields of speeds to the data obtained in similar studies. Results of the work demonstrate that for this class of experiments the best results were obtained with polyamide particles.

Krylov A. A., Korniyuk D. V. Technological approaches to zero offset compensation in MEMS gyroscopes being a part of the inertial measurement unit. Trudy MAI, 2018, no 103,

The work describes one of the calibration algorithms for MEMS gyroscopes as part of a small-size IMU, and technological process of calibration data acquisition. The IMU consists of three mutually orthogonal angular velocity sensors and microcontroller. Microcontroller corrects the original data acquired from gyroscopes by compensation functions describing the known systematic errors with computed coefficients. The article declares physical specifics of zero offset origin. Resizing of silicon cells and electronic elements, which process data from capacitive sensors, induced by temperature variation, leads to the change of sensitive elements oscillations, and, as a result, to the deviation of original frequencies. The temperature change has also leads to the vacuum pressure change due getter properties variation. The article presents a method for zero offset dividing into components. The two main components are the initial offset and the temperature drift. The initial offset depends also on the environmental temperature, but it can be compensated by the initial calibration. It is shown that the drift behavior is correlated to the internal temperature rising. The article presents a review of the applicable zero drift compensation methods for micromechanical gyroscopes. Most of these methods do not account for the temperature variation. In this regard, a new algorithm of zero drift approximation is proposed. It contains piecewise linear functions with weights corresponding to temperature rising in segments. As another error, the zero drift has instability and, as a result, can be evaluated by systematic and stochastic components. Using several independent switch-on-switch-off cycles we can accumulate statistics and highlight systematic component by computing the arithmetic mean. The IMU can be calibrated by several temperature points in operating range. The article demonstrates case of algorithm working in random conditions (temperature point). The intermediate points values calculation is also performed in piecewise linear function. For automatiion purposes this method was realized programably with algorithm of automatic calibration points search. The algorithm is based on the drift function smoothing by low-frequency filtering. The filtered signal can be analyzed as a function with a number of the most noticeable inflections. These points can be found as pertaining to the most acute angle. The algorithm allows reducing the zero drift by 5-20 times compared to the values obtained without compensation. Compared to the polynomial approximation of the third and fourth power, the drift value for the piecewise linear approximation appeared to be 2-3 times less.

Matafonov D. E. Developing and Completion of a SpaceWire Router based on a Russian-Made Field Programmable Gate Array. Trudy MAI, 2018, no 103,

The growing popularity of small spacecraft and increasing requirements to the onboard control systems performance necessitate consideration of various variants of architectures. Classic bus solutions are approaching their performance limits due to the increasing number of connected modules, as well as introducing the risk to the system functioning in case of a line failure. Transition to a network architecture is proposed as one of the possible solutions to these problems.

The article considers the FPGA as a possible variant for the degree of integration enhancement to mass and size characteristics reduction, as well as productivity increase. Since domestic designs allow application of the Russian-produced components only, it was rather problematic to implement miscellaneous logics in FPGA, before the 5578TC094 chip appeared. Its research prototype was obtained by FSUE MEDB “Mars” in 2017.

The 5-port breadboard model of a SpaceWire router was fabricated to evaluate the functionality of this FPGA and integrated controller parameters. The built-in LVDS transceivers characteristics were measured, and the SpaceWire channel was tested at speeds of 100 Mbps and 150 Mbps. A “byte doubling” effect was discovered and eliminated at 150 Mbps, which is approaching maximum operating frequency of 160 MHz of the FPGA project. The occupied logic capacity estimation revealed that the router could be combined with the other functional parts in one chip. For example, it could be conjugated with the other interfaces or programmable processor core.

The obtained results suggest a possibility of significant productivity enhancing of the onboard control systems by increasing the rate of exchange, as well as reveal the necessity of further studies in the field of fault-tolerance in the conditions of ionizing radiation.

Philatov V. I., Borukaeva A. O., Berdikov P. G. Algorithm for analyzing the consistency of expert estimates of the parameters of the hardware and software complex of the automated workplace. Trudy MAI, 2018, no 103,

This article tackles the issue of discordance of opinions of the experts and suggests a technique for the degree of compliance rate estimation. The concept of compliance estimation basis, namely, concord was considered. The algorithm for the experts’ opinions compliance analysis is described. The analysis on experts’ compliance estimation methods selection depending on quantitative and qualitative measuring scales usage, and measure of the degree of compliance was performed. The problem where

The problem in which there are many software and hardware workstations for aircrafts, having the same set of properties and properties in respect of each match quantitative evaluation experts group. The results of evaluations are presented in the form of a matrix. Described mathematical formalism concordance calculation coefficient – consent coefficient. It carries out a check of the algorithm as part of the expert survey, which resulted in peer reviews for all hardware and software complex of automated workplaces characteristics were obtained. These expert evaluations (expert group, consisting of 13 experts in the field of information systems) were tabulated. Using the data obtained was conducted analysis of variance in order study the characteristics of hardware and software of computer workstations. Created schematic block diagram describing the steps of parameters expert estimates the coherence algorithm APM compound hardware and software systems for aircraft. Calculated variance estimate and the concordance index (degree of coherence of software and hardware parameters workstations ratings people). As a result, estimated coefficient of concordance and relevance given the inequality which proves the validity of a good engine algorithms and to assess the consistency of expert APM AIC parameter estimates Connection program for aircraft.

The proposed method in this paper analyzes the consistency of expert opinion for all the characteristics of software and hardware of computer workstations is a hot topic that needs to be considered in the development of hardware and software for unmanned aerial vehicles.

Selvesyuk N. I., Veselov Y. G., Gaydenkov A. V., Ostrovsky A. S. Performance evaluation of objects detection and identification on an image from special optoelectronic systems for airfield observations. Trudy MAI, 2018, no 103,

The article considers the problem of determining the dependencies of detection and recognition characteristics of various objects in the airfield sector of observation from the equipment parameters and observation conditions. It describes the methods for determining a priori and posteriori estimates of image quality indicators obtained by optical-electronic observation systems. The article gives scientifically based recommendations on the image spatial-frequency characteristics reduction to the optimum values according to the criteria set by the operator performing visual analysis.

A posteriori assessment is based on the tests including the object of interest of a given class against the background of the underlying surface. The subject of the assessment is the image of the scene (object and background). Observation characteristics of the scene are determined by the evaluation of the geometric and contrasting characteristics of the image of the object of interest, the frame size and the problem solving time. The proposed a posteriori estimation method of the characteristics of observation of objects of interest allows estimate the probability of object detecting on digital images when conducting field tests with a minimum of computational costs and special equipment.

The a priori estimate is based on calculations including parameters of the optical-electronic system, with those obtained using special test equipment among them, as well as the required observation conditions. The article presents and describes in detail the a priori method for estimating the characteristics of observing objects of interest, proposed by the authors. The a priori assessment of the observation characteristics is based on the modulation transfer functions apparatus, as well as the threshold modulation characteristics. It consists in automatically estimating the resolution in the laboratory using experimentally obtained transfer characteristics based on test objects of various configurations. It is shown, that the proposed method provides the possibility of a reliable analytical evaluation of the observation characteristics for arbitrary ranges, sizes and contrasts of the object of interest, fields of view of the optical-electronic system and meteorological conditions.

The prospects for the development of methodological apparatus for determining the characteristics of objects detection and recognition are considered. The main attention is paid to the implementation of algorithm for the search function of the eye transfer function, the corresponding camera transfer function, as well as methods for characteristics assessing of the camera ringing.

Application of the method of reliable a priori evaluation of the observation characteristics reduces the material and time costs of conducting tests of video surveillance systems of airfield objects and is of great practical interest. However, the a priori assessment (and method) requires calibration and verification based on the a posteriori direct field test method.

The presented methodological apparatus can be used for the tasks of remote airfield control services using non-radar technical means of monitoring the situation on the airfield.

Karelin A. V., Skripachev V. O., Tumanov M. V., Zhukov A. O. Small spacecraft onboard scientific equipment configuration forming technique for the Earth radioactive contamination monitoring. Trudy MAI, 2018, no 103,

The article presents the technique for small geophysical spacecraft onboard scientific equipment forming for the Earth radioactive contamination monitoring. Monitoring of different hazards, including hydro-meteorological and geophysical phenomena, is possible with traditional space systems of remote Earth sensing. The number of potential sources of radioactive contamination increased with the beginning of industrial application of nuclear energy in developed countries, In the present economic situation in the country, the issue of minimizing costs of new space remote sensing spacecraft constellations creation is at the forefront. However, in view of limitations imposed on the configuration of a spacecraft onboard scientific payload (requirements for energy consumption, weight, size, etc.), the necessary onboard scientific payload implementation on a small spacecraft may present a difficult task. To justify the rational configuration of the onboard scientific payload, it is expedient to employ expert evaluation methods. The most promising methods based on determining physical effects occurring under the action of ionizing radiation have been determined to perform the remote radioactive contamination monitoring. Since the nomenclature of the on-board scientific payload is rather wide, we shall confine ourselves to the following types of instruments: a visible-range spectrometer, an infrared spectrometer, a microwave radiometer, an onboard ionosonde, and a radio frequency analyzer. We use the method of sequential comparisons to determine the utility of the on-board scientific payload. The present study shows the principal possibility of employing the method of successive comparisons to determine rational configuration of a small spacecraft for radioactive contamination monitoring. The developed technique can also be employed while developing the appearance of for various purposes small spacecraft.

Lyalin K. S., Khasanov M. K., Meleshin Y. M., Kuzmin I. A. Spectral method for ACF side lobes suppression for long pseudo-random binary sequences. Trudy MAI, 2018, no 103,

Signals with internal modulation are employed in aviation and space remote sensing systems to obtain a high-quality radar image. This approach allows reaching high image resolution preserving the high signal to noise ratio. The main disadvantage of this approach is sufficient growth of side lobe level. This drawback occurs in a radar image as bright strips that spread out of point or group targets along the range axis. This effect degrades sufficiently the ability to sense the image by human eye and automatically process the image. A typical dynamic range of radar targets brightness is 90 dB, wherein the best side lobe level, which has been achieved in this work is −35 dB by using of phase-shift keying signal of base 2000 and with matched range filtering.

One way to suppress side lobes is unmatched or quasi-optimal filtering, in which the core of the matched filter is changed to achieve desired optimum characteristics, with some loss of effective signal energy. In this work, a method for obtaining the coefficients of a quasi-optimal filter is proposed. The filter allows completely suppress the side lobes in the survey band by pushing them out of the visible radar image range.

The method uses a simple approach of transforming the desired form of the signal response fr om time to frequency domain, wh ere it is possible to find the relation between the input and desired signals, performing the “reciprocal convolution” which corresponds to the quasi-optimal filter impulse response. The main issue here is the difference between the amount of points in the input and output signals, as the output has to be the bigger length of impulse response. We solve the issue by adding additional points to the input signal, which result in a noise-like signal at the output signal’s edges. By selecting the appropriate amount of the “dummy” points we are able to establish the sidelobe-clean region in the output signal.

The article presents theoretical details as well as simulated and practical results.

Alekseev V. V., Lakomov D. V. Analytical model for graphic images processing in the city life-support systems for objects damages detection. Trudy MAI, 2018, no 103,

The article studies the possibility of application of the updated Canny algorithm supplemented with Robinson operator for images objects recognition and integrity violation detection of construction and housing and municipal services objects by an unmanned aerial vehicle in automated mode. It also describes Gauss filter application for the image blur, as well as special cases of boundary conditions for image pixels. The impact of the standard deviation value when blurring images on the image itself is demonstrated. The article describes a mathematical model of image analysis, based on the Robinson operator, and other applicable mathematical operators for embedding gradient values in image pixels. The Robinson operator, by convolution of the original image in four directions, allows more accurate search for the contour, compared to the other operators (Roberts, Sobel, Pruitt, Gauss, Laplace), which use only two directions of convolution. The results of this method studies while processing images of various objects of housing and communal services in the IR range are presented. Typical images of various objects in the infrared range were taken: transformer substations, electrical cables and sockets, heating pipes, heating mains, factory pipe, heat pipe, distribution panel, communication lines, a general picture of the city from the drone. Inferences were drawn the advantages and disadvantages of this analytical model, as well as the features of this model while the analysis of both clear and blurred images and the main obstacles in the images analysis. Based on this study, recommendations on the algorithm parameters selection are given. The conclusions made in this article can be employed in technical vision systems, as well as in decision support systems used to identify the damage to the analyzed objects in the field of urban planning and housing and communal services, as well as in other areas (Geology, agriculture and many others).

Sheludyak T. B. The Model of Digital Television Information Receiving in Spacecraft Ground Based Control Complex. Trudy MAI, 2018, no 103,

Television information is widely used for spaceflight control. Information plays an important role in daily management, dynamic operations performing and response to abnormal situations. Television systems upgrading to digital technology required some enhancements of the testing and monitoring features of digital television information of the ground based space flight control facility.

The article describes a computer simulation of the digital television information receiving system. The system was developed to analyze the processes of generation, coding, compression and transmission over the digital television information communication channels coming from the Russian Segment of the International Space Station, as well as cargo and manned spacecraft operating with the Space Station.

The simulation runs on a VMWare virtual server with the GNS3-simulated network structure. The proposed model allows simulate the main elements of a television system employed for the flight control. The model is applicable for the digital television information receiving system testing in various circumstances, or planning its performance in case of its modernization.

A system monitoring feature has been developed, based on simulation of the described ground based space flight control facility digital television information which was implemented with the PRTG software. It allowed simulate the following emergencies: communication channels interruption; hardware failure; various traffic loading in channels; hardware setup errors, and television signal source jamming.

The receiving system simulation functioning was verified along with digital television information test casts during the broadband satellite and fiber optic trunk channels deployment for ground based Russian Segment of the International Space Station control system.

Baghdasaryan G. Y., Mikilyan M. A., Vardanyan I. A., Panteleyev A. V. Closed cylindrical shell in a supersonic gas flow in the presence of a non-uniform temperature field. Trudy MAI, 2018, no 103,

The article considers the problem of stability of a closed cylindrical shell under the action of an inhomogeneous temperature field and a supersonic gas flow, flowing around the shell. The authors obtained stability conditions for the unperturbed state of the aerothermoelastic system under consideration. It is shown, that the combined action of the temperature field and the ambient flow can control the process of stability, and change significantly the value of the flutter critical velocity by means of the temperature field.

The study is based on the following well-known assumptions:

a) Kirchhoff-Love's hypothesis on undeformable normals;

b) “The law of flat sections” in determining the aerodynamic pressure;

c) The linear law of temperature variation over the thickness of the shell;

d) The Neumann hypothesis on the absence of the temperature changes.

For simplicity and clarity, it is assumed that the heat exchange with the environment from the shell front surfaces proceeds according to the Newton – Richman law (the temperature remains constant on the surfaces), and the side surfaces are thermally insulated.

Under the action of a stationary temperature field, non-uniform in thickness, the shell bulges (with deflection and longitudinal movement) and, as a result, the aeroelastic pressure occurs. The above said bulging state is presumed unperturbed, and its stability is being studied under the action of the temperature field and the pressure of the flowing gas flow. Stability regions are plotted, and the the critical velocity values are obtained. Numerical computations revealed that accounting for the effect of thermoelastic stresses of the unperturbed state on the stability region is essential. The computational results of the critical velocity for the combined effect of the temperature field parameters and various values of geometric parameters are presented.

Chepko I. N., Bogomolov D. V., Karpenko O. N. Managing the units and spare parts inventory for the State aviation equipment: the main problems and ways of solution. Trudy MAI, 2018, no 103,

The article considers the basic principles of the stocks management system. The uniqueness of the approach to the repaired units inventory management for operation of difficult products ensuring is proved. The purpose of the presented work consists in the analysis of the existing planning tools and inventory management. The analysis of the conventional technologies of inventory management application in the system of planning and inventory management of the repaired units to ensure operation of aircraft of the State aviation was performed. The history of the theory of inventory management was studied. Contradictions between the growing quantity of both complexity of the new problems of aircraft application, and old standard technology of planning and units inventory management are revealed. The fact that 60% of all airplanes stand idle in faulty condition due to the lack of spare parts is the vivid illustration to it. Application of probabilistic approach to the description of the processes of stock management of the repaired aircraft units was justified. Application of imitation modeling as an instrument of planning and managing the multinomenclature stocks of units for aircraft operation was proved as well. The article describes the two-level system for planning and inventory management of units for of aircraft operation as a part of association is described. The principles applied for the mathematical METRIC models description are used. The effective planning tool is simulation with application of real databases of statistical information. The necessity for modern technical developments application, in particular, in the field of information technologies when planning stock of units for aircraft operation of the State aviation is proved. Probabilistic approach application for description of the system of planning and inventory management of the repaired units is proved The functioning efficiency of the system for planning and inventory management of units is estimated by two parameters: the level of failures (service) elimination, and units shortage level. The authors suggest employing the marginal analysis technology to create the optimum plot of the units stock dependence on the amount of deficiencies. Imitation modeling application in the system for planning and inventory management of units is aimed at costs minimization on the product life cycle when ensuring the required parameters of the reliability, readiness, and maintainability of an aircraft of the State aviation.

Gusev P. Y. Planning automation of production process at aircraft building enterprise employing a digital replica. Trudy MAI, 2018, no 103,

The problems of production processes planning of aircraft building enterprises are of particular relevance. There are many software products based on theoretical planning concepts, such as CRP, APS, MES to solve such problems. However, such software do not ensure adequate feedback with production, which does not allow respond promptly to deviations from the plan. The purpose of this work consists in searching for possible solutions to ensure the operational control of the production plan implementation and its optimization. To achieve this goal, a decision was taken to apply a digital production replica, based on a simulation model.

A working plan developing for a production unit employing a ready-made simulation model is not a time-consuming task. However, while application of such plan, a lot of difficulties occur. Primarily, there is the problem of shift daily tasks preparing. The second problem arises with the impossibility to fulfill the developed plan. To solve such problems, the author proposes to employ an automated planning system using a digital replica of production. The two software clients have been developed to ensure interaction of the digital replica with the planning department and manufacturing facility’s level of production. The software client of the planning department allows prepare plans automatically for the enterprise production processes. The software for manufacturing facility level can encompass all employees of the enterprise. The information terminals provide an automatic transmitting of the shift daily tasks to the manufacturing facility level.

The proposed automated planning system demonstrated high accuracy in complex application. For example, when planning production processes at a workshop for the parts production from polymer composite materials, the digital replica contained information on the entire production system. Thus, when developing a working plan for one of the sections, all possible paths of material flows intersection of the other sections were computed. Use of automated planning of production processes of the workshop for the production of parts from polymer composite materials has significantly improved the accuracy of calculating the timing of the finished product.

Privalov A. E., Dorozhko I. V., Zaharova E. A., Kopeyka A. L. Simulation model for assessing the availability of technical systems taking into account characteristics of the diagnostic process. Trudy MAI, 2018, no 103,

In the development of complex technical systems accompanied by their life cycle, it is necessary to maintain readiness for use, which requires the development of new complex models linking reliability indicators and technical condition diagnostics indicators.

The proposed approach and models are based on the basic concepts and relations of the theory of reliability of technical systems. The models proposed in the article are based on the well-known and approved apparatus of Markov random processes, analytical dependencies are obtained from solving systems of Kolmogorov-Chapman equations describing the developed models.

Mathematical models have been developed that relate the availability factor, the reliability of the control of a complex technical system. A simulation model has been developed that relates the reliability indicators of a complex technical system and indicators of the technical condition diagnosing process. Analysis of the results allows us to conclude about the degree of influence of the characteristics of the diagnostic process on the availability of a complex technical system.

The proposed scientific and methodological approach can be used in the development of a complex technical system, as well as to justify the approximate values ​​of the periodicity of monitoring and diagnosing CTS, as well as to form a sequence and composition of inspections in order to increase availability.

The obtained analytical dependence may be of practical interest for military representatives, employees of state certification of products, industry representatives and can be used in the formation and justification of reliability requirements in the tactical and technical tasks for the development (modernization) of a complex technical system, as well as to take into account the influence of process characteristics diagnosing the availability of a complex technical system at all stages of the life cycle.

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,

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,

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 N2 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 N2 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 N2 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,

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:

  1. On the impact of natural-convective flow on formation of various stationary convective flow structures and occurrence of countercurrents to the main flow in long horizontal layers.

  2. The problem of the symmetry violation of a steady flow in a plane diffuser.

  3. The effect of controlled vibrations on heat and mass transfer in the melt, the shape of the crystallization front and the thickness of the boundary layers and on the shape of the crystallization front.

  4. Interface location changing under the impact of thermocapillary convection.

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,

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,

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,

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,

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,

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,

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,

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., Vasil'ev 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,

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,

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,

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,

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,

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,

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,

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:

  • Provide information on the studied course, both at the level of the simplest concepts, and in the form of methodical grants;

  • Store information on the contingent of students and their steps on mastering the discipline materials (with assessment of the progress);

  • Present results of work with system at users request according the level of access both to the students, and the tutor.

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,

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,

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,

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,

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:

  1. Forming imitation recurrent approach to electric devices degradation processes studying and modeling;

  2. Developing mathematical models of nonlinear degradation processes and characteristics of electric devices;

  3. Performing estimation of electric devices fault free operation and their residual resource according to the change of degradation deflection of the characteristic parameter. Such estimate employing allows significantly simplify modeling and reduce the order of the system of equations.

  4. Forming comprehensive information while the power grid turn-off in the run-down process on the induction motor functional state, the degree of degradation wearout and duration of the residual resource.

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,

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,

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,

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,

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,

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.

Le T. D., Nesterenko V. G. Study and optimization of the thermal state and acceptable level of stresses in the shroud of the turbine rotor blades of a gas generator of aviation high-temperature gas turbine engine. Trudy MAI, 2018, no 102,

The article presents a technique for shrouds of gas generators’ turbine rotor blades designing for conventional and prospective high-temperature gas turbine engines to increase their efficiency, service life and reliability through their cyclic strength in particular. Based on the results of the design studies of temperature state and strength characteristics evaluation of the airfoil blades and their shroud shelves of various configurations, a technique allowing optimize their convective-film cooling was developed. With account for the increased strength characteristics of heat-resistant alloys with rhenium additives, this technique allows designing the shrouds of the high-temperature turbine blades of new generation, while maintaining the required level of allowable stresses and safety margins.

The purpose of the study consisted in identifying the critical areas of the shroud, as well as the airfoil blades requiring increased cooling intensity at reasonable costs of the cooling air. The shroud is usually calculated on bending under the centrifugal forces action, as a cantilever beam of variable cross-section, embedded into the section adjacent to the airfoil blade. A shroud cooling system, which ensures a temperature reduction of the blade of the high-pressure turbine, where the stress values in the shroud are maximum, has been developed. The parameters for the temperature and stress state calculation of the turbine blade shroud of a gas generator were selected to maximize the mode To simulate the viscous flow of incompressible gas in the turbines flow passage, the Navier-Stokes equation was used. In the flow passage domain, a tetra grid was used. On the gas domain surface, a thickening of the grid with 10th prismatic sub-layers was created.

The results of the conducted studies allowed obtain practically significant conclusions and recommendations, which also have a scientific novelty associated with the specification of the nature of the gas flow and the expedient employing of the convective or film cooling in different parts of the shroud and the airfoil blade.

Tran L. T., Tarlakovsky D. V. Moment Elastic Half-Plane under the Action of Surface Non-Stationary Normal Displacements. Trudy MAI, 2018, no 102,

The article discusses an elastic homogeneous isotropic half-plane filled with a Cosserat medium. At the initial moment of time and at infinity, there are no perturbations. On the border of a half-plane, non-stationary normal displacements are given. All components of the stress-strain state are limited. A complete system of equations of the asymmetric theory of elasticity is presented, which includes linear vector equations of motion in displacements, geometric and physical relations. Using the representation of fields of displacement in the form of potential and solenoidal parts, a system of equations of motion with respect to the scalar, vector displacement potentials and angle of rotation is written.

For the plane problem in question, a rectangular Cartesian coordinate system is used. The resolving system of equations includes three hyperbolic equations for the scalar potential, the nonzero component of the vector potential, and the rotation vector. The solution of the problem is sought in the form of convolutions of a given normal displacement with the corresponding surface Green functions. To construct the latter, we apply the Fourier transform with respect to the coordinate and the Laplace in time. The originals of the images are found using the joint inversion of the Fourier and Laplace transforms.

Examples of the action of various non-stationary loads on the border of a half-plane and examples of calculations for a granular composite of aluminum shot in an epoxy matrix are given.

As results of this article, an analytical solution is constructed for the problem of the propagation of non-stationary surface kinematic perturbations in the moment-elastic half-plane, which allows using quadratures to find stresses for any law of load variation. It is established that the corrections made to the solution, taking into account the moment properties of the medium, have the order of the coefficient relating the fields of displacement and rotation. It is shown that the surface Green’s functions in this case have an integrable singularity at the front of the shear wave.

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,

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,

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,

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
Ef = 200 GPa with two types of insertions, namely, hard with elasticity modulus of
Ef = 180 GPa, and soft with elasticity modulus of Ef = 1 kPa was considered.

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,

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,

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,

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,

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,

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 θIGV significantly impacts on size, angle and direction of downwash. When θIGV<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 θIGV~95° IGV outflow has axial direction, and velocity distribution at rotor inlet consists to expected. When θIGV>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.

Bolsunovskii 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,

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 χ1/4 = 32.7° and average relative thickness of t/c=11.2%, while for the more high-speed wing the sweep was increased up to χ1/4=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,

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,

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,

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,

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,

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,

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,

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,

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,

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,

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,

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,

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,

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,

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,

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 fx и fx 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.

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,

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
γAFM-APM = 20 bit/s/Hz.

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 Ebit/N0 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 qbit = 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,

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,

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:

  • An approach to the design parameters definition at a nominal trajectory,

  • An approach to the design parameters selection from the extreme conditions,

  • A probabilistic approach with account for the random nature of severe environment.

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,

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,

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,

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,

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,

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,

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 do = 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 do = 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,

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,

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,

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&n