2016. № 85
Study of orbital stability for planar oscillations of a magnetized symmetric satellite in a circular orbit
It is considered the motion of a satellite about its center of mass in a central Newtonian gravitational field. The satellite is a magnetized dynamically symmetrical rigid body, whose typical linear dimensions are small compared to the radius-vector of the mass center. The above assumption allows us to consider the problem in a restricted formulation, that is we assume that the motion of the satellite about the center of gravity does not affect the motion of the center of mass . It is also assumed that the orbit of the center of mass is circular. The orientation of the satellite relative to the orbital coordinate system is described by Euler angles ψ, θ, φ.
In this paper it is assumed that magnetic moment arises from the magnetization of the material of satellite shell by earth’s magnetic field [1, 4, 5]. Earth’s geomagnetic field is described by dipole model . It is assumed that the Earth’s magnetic dipole axis coincides with the axis of rotation (direct dipole), and the orbit of the satellite lies in the equator plane.
Under these assumptions, the equations of motion of the magnetized satellite about the center of mass can be written in Hamiltonian form. One of the generalized coordinates (proper rotation angle φ) is a cyclic coordinate, so the corresponding momentum pφ is the first integral of the motion. Planar periodic motions are possible only if pφ=0. It is assumed that the perturbations satisfy the above equality.
The problem has three parameters: the parameter β, which characterizes the geometry of the masses; the parameter ξ, characterizes the effect of the magnetic field of the Earth; doubled amplitude of planar oscillations Ψ.
Linear analysis of the orbital stability for periodic motions is performed. The above motions are planar pendulum-like oscillations such that the polar principle axis of inertia is located in the plane of the orbit of the mass center. To this end local coordinates are introduced in the neighborhood of the unperturbed periodic motion and linearized equations are written.
Separately, it was considered the special case when amplitudes of the oscillations are small. In this case small parameter (doubled oscillation amplitude) has been introduced. It allowed to study the orbital stability analytically. In particular, using the normal forms theory the explicit formulas describing the boundaries of parametric resonance domains were obtained.
For oscillations with arbitrary amplitudes linear stability analysis based on the numerical integration of the linearized system has been performed. In typical cross-sections of the three-dimensional parameter space the domains of orbital instability and stability have been obtained. The results of numerical analysis of orbital stability are in good agreement with the results of analytical study performed in the above mentioned special case.
Keywords: Hamiltonian system, periodic orbits, normal form, resonance, action-angel variables, orbital stability
Aeronautical and Space-Rocket Engineering
Design, construction and manufacturing of flying vehicles
Research is directed to the solution of the task of designing and modernization of suction pipelines structure of hydraulic systems to improve resource using systems engineering analysis.
Purpose — development and testing the search technique and eliminating of hydrodynamic and vibratory cavitation in suction pipelines structure at various mode, including transient.
In this paper proposed solution technique of similar task. Technique consists of several basic steps.
Hydrodynamic analysis, by-turn, consists of the following steps:
Technique approbation was made by the example of suction pipelines section of hydraulic systems of modern aircraft wh ere possible cavitation.
Cavitation occurrence was noted during transient process of increase pump delivery from minimum to maximum. For a certain time inside of solution of quasistationary task the origins and the points of cavitation occurrence and the volumetric concentration value of saturated vapor.
The developed technique allowed to identify the pipelines section, including the points which are dangerous in the view of hydrodynamic cavitation occurrence and the points which are dangerous in the view of vibratory cavitation occurrence. Two variants of modernization were suggested. It was considered using the described technique. As a result of assessment changes the efficiency of one of the samples. At that, the data received as a result of simulation goes with real pattern inside the pipeline, it confirms correctness and justifiability of the suggested technique.
Keywords: hydraulic systems, pipeline, cavitation, vibration, resonance
Analysis of computational and experimental researches on systems for individual control of the blades of the helicopter
The article gives a review of methods for individual blade control of the helicopter rotor. Low and high harmonics control features in order to improve aerodynamic performance, reducing vibro g-load and noise of the helicopter were presented.
It is established that one of the directions of works to increase in flight speed is individual blades control of the helicopter rotor, which is the implement for addition control of the blades attack angles, superimposed on standard controls from the collective and cyclic pitch control mechanism. Researches abroad for individual blades control is aimed to reducing vibro g-load and noise of the main rotor, to improve the aerodynamic characteristics of the carrier system and finding ways of rejecting traditional collective and cyclic pitch control mechanism.
Individual blades control of the helicopter rotor can be divided into two components: 1) low harmonics control (rotational frequencies and their overtones) and 2) high harmonics control (blade frequencies pass and their overtones). The purpose of the low harmonics control is to improve the aerodynamic characteristics of the rotor by reducing areas of stall on the retreating blades of the rotor and approach angle of attack sections of the blades for the optimum profile quality. The purpose of the high harmonics control is to reduce vibro g-load and noise of helicopter rotor on the flight modes with large horizontal velocity.
The article describes the different methods used to individual blades control of the helicopter rotor:
The results of numerical investigation of the influence of individual blade control by azimuth by means of cyclic change of the angle of installation to reduce vibro g-load transmitted to the hub from helicopter main rotor.
The influence of the main (the fifth blade harmonic, for 5 blades rotor) harmonic was investigated. It is established that the selection of the amplitude and phase controls for separate blade is possible to minimize the amount of vibro g-load.
Keywords: rotors of the helicopter, drive, harmonics, vibro g-load, individual control of the blades
The purpose of this paper is to present an overview of bulkhead design problems, which can be efficiently solved using a special non-dimensional criterion of load-carruing efficiency.
Nowadays optimization algorithm based on fully-stress design philosophy and employing variable density model, is used. Such algorithm provide means to generate optimal load-carrying scheme of structures, subject to a wide range of design constraints.
Reinforced bulkheads are usually located in the areas of perception of concentrated loads fr om the wing, empennage, landing gear, etc. In the case of a wide range of engineering solutions, it is extremely important to assess different load-carrying schemes of bulkheads. Previously, a special criterion called «the load-carrying factor» was used for assessment of bulkhead load-carrying schemes. The load-carrying factor is the dimensional value which limits its the applicability to some extent. Therefore, new non-dimensional criterion was introduced for assessment of load-carrying efficiency of different bulkhead structures and knowledge accumulation.
This article takes into consideration reinforced bulkheads, loaded with the bending moment. The values of novel non-dimensional criterion were studied for different boundary condition in this research work. It was defined an area of geometric parameters wh ere exists some engineering solutions more advantageous than traditional beam with the constant structural height.
The developed non-dimensional criterion of load-carrying efficiency was used in the practical task of finding optimal bulkhead load-carrying scheme for maneuverable aircraft with two specific cutouts for the engine compartment. The obtained load-carrying scheme present the possibility of reducing the structural weight by 19%.
The non-dimensional criterion have predictive opportunities for assessment of different bulkhead load-carrying schemes at early design stages.
Keywords: design, reinforced bulkhead, load-carrying scheme, loads, bending moment, load-carrying factor, non-dimensional criterion of weight efficiency
This article describes a method, which allows to generate the aircraft plan view with a minimum number of iterations (revisions after aerodynamic and weight calculations results). The method is described by the example of the front-line aircraft layout scheme development (synthesis), front-line aircraft model made by the normal balancing scheme with two engines and internal cargo bays. The synthesis is carried out on the basis of pre-defined design parameters, constraints, and solutions, which are set by the designer, based on parametric relations and statistical relationships analysis.
Designer need to determine the so-called «Layout Field» on the stage of aircraft layout scheme synthesis. «Layout Field» is a plan view on the aircraft geometric shape formation initial stage. Plan view determines the load-bearing capacity and area chart, which defines aircraft volume and wave component in the aerodynamic drag increase.
Work is carried out taking into account the structure and division of tasks in the interconnected units, which sequential study allows to achieve the objectives. The transition to the formation of the plan view implies a preliminary definition of design parameters, boundary conditions and areas chart.
Design parameters determination, described in the work, carried out at the selected engine thrust based on the approximation of design parameters statistical dependencies of a number of existing fighter aircraft 3, 4 and 5 generations at a selected level of superiority over the prototypes according to the criteria of energy characteristics and the specific load carrying properties. Thus, to determine such parameters included in the methodology, as an area washed by the surface, the volume of the aircraft, space and lengthening the base of the wing.
The initial step is to determine the range of possible design parameter values (area of aircraft surface, aircraft volume, area and lengthening of the base wing), in which the method will be working out (verification) further. With the known range of the basic parameters and criteria, there is a further possibility to define the existence region of the main part of the design parameters. The rest of the plane parameters are determined on the basis of a design layout constraints based on the existence region of these parameters.
The presented method of determining rational variants of the airplane geometric shape in the early stages of design allows to pre-drop not implemented vectors of design decisions, which, in turn, will reduce the time and costs of the aircraft view synthesis and improve the quality.
The possibility of reducing the number of unnecessary options is realized at this stage, and thereby this will reduce labor and time for further analysis.
Keywords: shape, airplane, plan view, midship, layout, design
Strength and thermal conditions of flying vehicles
Modeling of settlement external thermal loadings to a spacecraft surface by means of infrared heaters
The article is devoted to the methodical approach for a choice of an optimum operating mode of the infrared simulator concerning the accuracy of modeling of an isotropic field of the radiant streams, which are let out in the direction of the examined object during the complex electrical tests in the heat vacuum camera. For this purpose it is necessary to provide the set temperature condition for an object at vacuum camera preparation stages and during the tests and, also, it is necessary to overcome the interval of environmental pressure, at which there is a possibility of electric breakdown of a gas interval. Achievement and maintenance of the demanded vacuum level (P≤10-3Ра) in the camera is connected to the need for maintenance enough low temperatures (less than 90K) on camera screens. In this regard there is a need to supply examined object by power offsetting its energy due to radiation of an external surface of elements and providing the demanded thermal mode. For realization of this approach to the solution to the considered task it is necessary to have the geometrical models of a thermostatically controlled surface of a product and the simulator, as well as the information about spectral and integrated radiation characteristics of elements of the object external surface and radiators of the simulator. Thus, the side modules of the simulator are located along forming surfaces of the circular cylinder coaxial with the vacuum camera, and face modules placed in the plane perpendicular to the camera axis and intended for thermostat control of bottom part of the examined object.
Methodical approach to optimization of the power operating mode of the simulator of external heat loads on the surface of spacecraft was implemented with the help of FORTRAN-oriented simulation program based on gradient methods for criterion functions minimization. The computational experiment was carried out for various levels of temperatures of thermostat control. Optimum values of the electric power brought to each module of the simulator are revealed and errors of reproduction of the demanded temperatures are defined.
Calculations showed that the infrared simulator without reflectors can provide a satisfactory thermostating of the most important external surfaces of the examined object during electrical tests in the conditions of modeling both of space vacuum and external thermal conditions in the range of temperatures [-10; 30] ° C for devices and the equipment without the use of bench heaters for internal heating.
Keywords: Simulator, optimization, heat load, spacecraft
Thermal engines, electric propulsion and power plants for flying vehicles
A one of the main trend in the design of compressor of fifth or sixth generation ofgas-turbine engine of highly-maneuverable aircrafts is reduction in the number of stages of compressor while keeping or increase efficiency, stall margin and other settings. In solving of this task highly important the support unseparated flow around working surfaces of compressor flow path, which can be support by a development method of flow control.
As such in VUNTs Air Force «Prof. N.E. Zhukovsky and Yu.A. Gagarin military and air academy» perform investigation of active control of flow pattern.
Work objective resides of developing effect method of active control of flow pattern in compressor rotor wheel of gas-turbine engine for further formation state of the art instruction.
The investigation is concerned withactive control of flow patternin compressor rotor wheel. Research subject is influence of active control of flow pattern of test medium.
Are described following method of active control of flow pattern included injection test medium:
Results of calculated investigation shows that these methods of active control of flow pattern allow increase any characteristics of compressor stage and compressor totally.
The control effect visualize on off-design point more than other, efficiency relies upon inject direction, injection force, and form, quantity, layout ofprofiled injection ports.
In departments of aviation engine be carried out research of test medium injection on compressor stage characteristics.
Next stage of work is simulation of active control of axial flow compressor of gas turbine engine.
These methods of active control will let to improve characteristics not onlyfifth or more generation of aircraft engine, but also4++ generation. Also these methods may be used in earth-based power plant, whichwill take a positive economic effect.
Keywords: . active control of flow pattern, axial compressor, profiled injection ports, blade tip clearance, rotor wheel hub
Development of the design and calculation method of plate heat exchanger for turbines with combined cycle
Currently one of the urgent problems of modern engineering practice is the problem of fuel efficiency. One of the solutions of this problem is to using the heat recovery. The key technology in this case is the heat exchanger (HE). One of the most important components of the designing of the HE is the method of a calculation and design. The purposes of the study are: development and verification the three-dimensional calculation method of the HE; development of the analytical evaluation program of calculation, on the basis of the criterion of dependencies from the three-dimensional calculation method; development of the parametric 3D-models of the HE plate and tools for its manufacturing.
In the study, the three-dimensional calculation and design method were developed and described. Development of parametric 3D-models and tools helps to reduce the time of design and preparing the calculation model. The test to verify three-dimensional calculation method was carried out. The verification of the method, basing on the test data, and additional verification, basing on criteria dependencies were performed. As part of the verification a structured hex-mesh and an automatic tetra-mesh were considered. In the frame of practical work the most convenient option of the mesh was chosen. Basing on the three-dimensional calculation research the evaluated analytical program was developed. This program is used to obtain a preliminary assessment of the heat transfer surface with given geometric parameters and operating modes of HE.Considered method is used to obtain a preliminary assessment of the heat transfer surface with the specified geometric parameters and operating modes of the heat exchanger. This allows reducing development time and cost of full-scale tests.
Keywords: fuel efficiency, complicated thermodynamic cycles, heat exchanger, three-dimensional design, parametric design, evaluated calculation method
The topic of the article, which is closely linked to the environmental criteria of Russian aviation industry, was chosen not only because of the considerations of the aviation Institute profile and the professional specialization of the authors, but, mostly, due to the relevance of the innovations and knowledge-based areas defined by the Governmental Commission on modernization and technological development of the economy in Russia.
The article analyze the impact of a toughened environmental regulations on profit growth and the development of knowledge-intensive industries, such as aircraft engine industry.
In order to perform a sustainable research we used mathematical models of the development processes and interaction between the ecological and economical requirements in primary and secondary markets of the high-tech industries.
The subjects of the mathematical modeling data were the calculations of the maximum and minimum periods of the environmental standards revision needed to revive the demand on the aircraft engine manufacturing market and to maintain the optimal marginal values of the aircraft manufacturers and companies engaged in air transportation.
The presence of the secondary market of science-intensive production allows to harmonize the interests of aircraft manufacturers seeking to increase the demand for their products, and consumers of those products. The companies that are engaged in the air transportation decrease their losses on the technical issues during forced updates caused by the new environmental standards.
Based on the results obtained, we have formulated several findings about possible harmonization of the environmental and economical interests of the participants of aeronautical engineering and aircraft operation.
The similarities in the development patterns of the aviation engineering market and market development of the high-tech industries and other innovation clusters were found.
Finally, we propose a list of important directions to the future scientific research and construction work in the field of aeronautical engineering based on the analysis performed.
The obtained findings regarding the impact of toughened environmental requirements in the environmental cluster development process on the aviation engine building can be applicable and useful to predict the development of other areas of innovation.
Keywords: Aircraft engine, aerospace industry, environmental protection, environmental regulations, economic demands, international civil aviation organization, emissions, noise, effective perceived noise level
Control and testing of flying vehicles and their systems
This article discusses the impact of built-in test dependability, fault- detection and isolation ratio on reliability of redundant systems. The results and conclusions of the article focused on responsible usage systems with high reliability and safety requirements. We present probabilistic approach to assessing the quality of built-in test based on splitting the total flow of system failures into two components — the failures, detected by the control, and latent failures. In this case the main testability index, fault detection ratio, can be defined as conditional probability of failure detection, provided that the failure occurred. The usefulness of such approach is possibility of joint reliability&testability modeling of aviation systems. We have developed a number of reliability models of typical redundant schemes that take into account parameters of built-in test. Markov reliability models were constructed for the following structures: unredundant scheme with imperfect built-in test and special recovery strategy; classical redundant structure with imperfect built-in test and graceful degradation, consisting of two parallel operating elements; redundant structure with imperfect built-in test, consisting of two parallel elements, operating in a master-slave mode; «2 out of 3» redundant scheme with repairable elements and imperfect fault coverage. Dependences of reliability and availability indices upon fault-detection ratio were investigated. Investigations were carried out on such indices as mean time to failure, probability of failure-free operation, probability of dangerous failure, operational availability factor. We have demonstrated the strong dependence of these indices on the quality of built-in test. Construction and analysis of such models allows the designer to justify the requirements to built-in test and maintenance parameters.
Keywords: reliability, testability, redundant schemes, fault-detection ratio, fault-isolation ratio
Dynamics, ballistics, movement control of flying vehicles
Solving various tasks in celestial mechanics and space dynamic, as unperturbed motion the movement on three types of trajectories such as elliptic, parabolic, and hyperbolic which are characterized by the value of eccentricity, have been used. It is convenient to specify the laws of motion along these trajectories in a parametric form. However, the existing parametric formulas for setting motion have one serious drawback as they have a different functional form for each type of trajectory. This circumstance had not caused a particular concern before the beginning of the space age, since the transition from one trajectory to another for very large space objects in move was virtually impossible. With the advent of spacecraft equipped with thrusters, such transitions have become possible as the engine operation change the value of eccentricity. The existing parameterization could not be used for these transitions theoretical studies, since one parameterization will not enter another while a continuous variation of the eccentricity. So, performing these calculations, it seems inconvenient to describe the transition of the spacecraft from one orbit to another, and it is not clear at what point you need to start using another parameterization.
To eliminate this non-analytic behaviour of the formulae in the transition of the eccentricity using the value of one, in this paper a unified parametrization that enables such a transition has been we construct. This enables to describe the motion of the spacecraft under the action of the thrusters with a continuous transition from one orbit type to another one, using the unified parameterization for the organization of iterative scheme of the method of successive approximations ( a method of osculating elements in a more general scheme). In this scheme, in the initial approximation the eccentricity, the argument and the orientation angles of the orbit in space are considered constant. The following approximation is taken into account a small variation of these orbital elements under the action of a thruster. Consistent application of this iterative scheme with unified parameterization allows to obtain both analytical and numerical solution of the problem on motion of a spacecraft moving from one orbit type to another.
Keywords: parametrization of the trajectories, the eccentricity, the Kepler problem
The spatial spread of the solar sail, in which the shape of the surface of the membrane is maintained by centrifugal forces, is considered. A mathematical model of the solar sail is represented as a set of approximating circles connected by a thin stretched weightless membrane . The surface shape of the rotating membrane in the case effect of the sunlight pressure on the membrane is investigated. Since the membrane deviation is a minor value compared with its radius, the pressure effect of the sunlight on the surface shape of the solar sail cloth in the further investigation was not considered. Also, the surface shape of the solar sail in the case of a uniform rotary motion in the time of its reorientation was simulated. Dependences of deviation of the outer edge of the membrane from the plane, in which the rigid insert lies, at different radiuses of the rigid insert and at different angular velocities were constructed. The problem of the active damping of the membrane fluctuations was considered. A finite-dimensional system obtained as a result of the approximation of the membrane by several circles, was investigated. The roots of its characteristic polynomial, which determine the natural frequencies of the membrane fluctuations, turned out to be greatly separated from each other. In this regard, only the first non-zero frequency was solved to damp. Control law, which transfers the roots of the characteristic polynomial in the left half-plane and provides damping, was suggested. Transients by the angels, that define the spatial position of the solar sail, were obtained in the case the shift of the roots to the left half-plane.
Keywords: solar sail, elastic mode control, the surface shape of the rotating membrane
In air surveillance mode, fighter’s airborne sighting systems make use of air target motion coordinate and parameter assessment algorithms based on α,β-filtering with low data update rate which is insufficiently effective in close maneuver air combat environment and doesn’t provide aimed engagement of air target.
One of the possible ways to overcome the noted shortcoming is air target motion coordinate and parameter extrapolation accuracy enhancement using more complex models of spatial target motion, Song model in particular.
Objective of this paper is to define Song model characteristics to improve air target motion coordinate and parameter extrapolation accuracy in close maneuver air combat with low target data update rate.
To specify Song model characteristics, it is required to define maneuverability factor values at maneuvering of fighter relatively air target in close maneuver air combat with execution of «Combat turn» and «Oblique loop» space maneuvers, «Rolling» and «Ordinary loop» vertical maneuvers and «Banking» yaw maneuver.
To accomplish the objective, there was performed semi-realistic simulation of close maneuver air combat resulting in definition of ensemble of realizations for random process of closure jerk (third range derivative) for each type of air target maneuver. This enabled to calculate experimental correlation functions of lighter-to air target closure jerk averaged by the number of realizations.
Maneuverability factor was estimated using spectra-correlation processing via transition from time domain to spectral domain — direct Fourier transform.
To validate practicability for employment of the results obtained, there was performed comparative analysis of range extrapolation accuracy to air target. Absolute magnitude of extrapolated estimate error was taken as accuracy figure.
Improvement in accuracy of range extrapolation to air target for Song model, as compared with second-order air target motion model, can achieve 18%, 15% — with rectilinear uniform motion model and 11% — with Singer model.
So, based on spectral-correlation processing of the semi-natural experiment results, there were defined parameter values of Song model describing spatial relative motion of fighter and air target in close maneuver air combat. The comparative analysis proved availability of improvement in accuracy of air target coordinate extrapolation with making use of the refined Song model. Employment of this model together with prior uncertainty handling algorithms relatively type of air target maneuver, Mane parametric identification algorithm in a fighter’s airborne sighting systems will provide improvement in accuracy of coordinate and motion parameter estimation in the air surveillance mode and, as a consequence, improvement in accuracy of weapon delivery.
Keywords: air target, Song model, maneuverability factor, spectral-correlation processing
Instrument making, metrology, information and measuring equipment and systems
Information and measuring and control systems
The system of satellite control of aircraft systems (Unified Information System Of Interaction (SWIM.ru))
Currently in the world there is an urgent practical need for a creation of single information system for operational awareness of the movement of aircrafts of various departments of airspace users.
If we talk about safety, it is directly related to the operational situational awareness of the progress of the flight. This also applies to operational awareness in the air and on the ground. Over time there will appear more and more modern means of operational monitoring and registering the crash site, the aircrafts will no longer disappear without a trace, but this is not the goal of solving the existing problems. The most important goal is to always avoid losing aircrafts out of sight with the help of the new information technologies.
The system is based on the statement: «Improving safety is ensured by the development of operational information interaction between the airspace users (ATC, airports, airlines, etc.) in order to create safe and efficient flow of aircrafts both on the ground, and during all the phases of flight».
Today the solution to this problem in the Russian Federation should not be considered outdated in comparison with the achievements of other countries. The staff of the Resource Center of Scientific Research and Innovative Technologies (RC SRIT) MAI (National Research University) together with specialists of LLC «Softaero», FSUE «GosNIIAS», and the Keldysh Institute of Applied Mathematics (Russian Academy of Sciences) developed and brought to practical application the Unified Information System Of Interaction (SWIM.ru), aimed at solving tasks of automatic control of flows of aircrafts. This system of operational situational awareness is based on cloud technology in order to provide information service to air traffic control, airports, airlines and handling companies. The system analyzes the current air situation and recommends actions for the organization of stable (safe and efficient) course of arrivals (Aman) and departures (academy) of aircrafts.
The project has passed the «point of no return» and today the projects are in the preparation phase of the implementation of SWIM.ru for foreign airlines. Other goals are creation of learning courses using on-line situations from SWIM.ru, the interaction with EUROCONTROL, preparation of other special projects. It is worth noting that the complex is being developed by national enterprises with 100% national software and national equipment like transmitters via the iridium satellite network, AZN-V 1090, video cameras and other components. This system is successfully tested on the aircrafts of Russia, can be also used on ground vehicles, including combat vehicles and on ships.
Keywords: flight safety, operational situational awareness, information complex, satellite-based monitoring
Radio engineering and communication
Radio engineering, including TV systems and devices
Presently different methods of flight safety management system are developed. One of the most important methods is a prognostic method based on predicting the occurrence of a situation. The prognostic method of flight safety management system is widely implemented in the diagnosis of aircraft systems health monitoring. This article reviews the diagnostic methods of forecasting technical condition of avionics equipment, a probabilistic method and numerical analysis method.
The probabilistic prognostic method allows to determine the probability of keeping a healthy state of the object of technical diagnostics, or vice versa, the probability of coming of inoperable conditions of avionics.
In Generally, probabilistic prognostic methods are very time-consuming, difficult to algorithmization. In addition, they require knowledge of the statistical characteristics of the electronic equipment, which is not always possible. In this case it is often more appropriate to apply the methods of numerical analysis.
The numerical analysis methods allow for forecasting technical condition without taking into account the probability of failure of elements belonging to the object of diagnosis (and other probability characteristics of electronic equipment). The availability of data about the previous conditions of aircraft radio-electronic equipment is required.
Based on abovementioned it is can be concluded that using of the appropriate mathematical apparatus makes it is possible the diagnostic data to estimate not only the current state of the aircraft radio-electronic equipment, but also to make its prediction state. At the same time as the mathematical apparatus is advisable to use a probabilistic method and numerical analysis. The main difference between these methods is that the probabilistic method takes into account the probability of each element of the system failure for calculating of the overall system failure probability. A numerical method does not take into account the probability of failure of the system elements, and is based on the analysis of the previous condition of the equipment.
In the district of applying the method allows to implement the principle of predictive safety management, as well as the economic effect of avoiding downtime of the aircraft due to a sudden failure of avionics.
Keywords: diagnostics, prognostics, probabilistic method of prognostics, numerical analysis method of prognostics
Antennas, SHF-devices and technologies
This article is about of the new solution to improve provides a data rate. The urgency of solving this task is associated with a deficit and limited frequency resource and the high cost of building new base stations for cellular communication systems. As such a method for reducing network overhead and maintaining high data rate, in growth the number of mobile subscribers, proposed integration of cellular networks, ad hoc network with a dynamic structure and Wi-Fi networks. The research is performed for developing Ad hoc network- Mobile Ad hoc Network (MANET). A MANET is an autonomous system of mobile nodes, which may operate in isolation, or may have gateways to and interface with a fixed network.
From the point of view of build combined networks with dynamic structure, the analysis of current structure of cellular networks and MANET was conduct. On the basis of the research operation of the mobile subscriber in MANET networks, developed the algorithm to work users in combined communication networks. This algorithm provides the satisfaction of quality of service (QOS) in the construction of the route, which is an integral part of all user networks.
Reviewed questions of construction combined MANET and cellular communication. Their functional scheme is built. In this scheme the transfer procedure for the by MANET technology begins in case a mobile subscriber outside of network coverage or failure to transmission from the network due to a lack of available channels.
Further research will be devoted to writing the mathematical apparatus of describing the operation of a combined network with a dynamic structure, which will allow evaluating the functioning and implementing a qualitative analysis of the developed system.
Keywords: networks with dynamic structure Ad hoc, GSM, UMTS, LTE, Wi-Fi, integration of communication systems
Radiolocation and radio navigation
Experiment-calculated estimation of industrial overhead transmission line interference influence on high-sensitivity radars
The capability of electrical and electronic systems, equipment, and devices to operate in their intended electromagnetic environment within a defined margin of safety, and at design levels or performance, without suffering or causing unacceptable degradation as a result of electromagnetic interference.
In condition to provide a function of inadmissible radio noise, at the stage of a choice in order to choose a point of a dislocation it’s essential to carry out the experimental analysis of an electromagnetic environment.
So far as the sensitivity of the existing measuring equipment is much lower than the sensitivity of the HSR radio-receiving device, according to all standard techniques, the results received from carrying out the experimental analysis of electromagnetic environment at the point of dislocation are incomplete. Therefore the data of an influence of electromagnetic environment on high can be obtained not only experimentally, but also by calculations.
This problem is particularly acute concerning overhead power transmission lines (PTL), the level of a man-made noise from PTL is impossible to capture on the point of HSR dislocation by the measuring equipment.
Therefore in order to receive the fuller results on electromagnetic environment it is necessary to carry out a settlement and experimental assessment of influence of PTL on HSR.
At the first stage it is essential to take measurements of levels of intensity of the electric field of a man-made noise according to GOST 22012-82.
The measured level of a man-made noise needs to be recalculated in the HSR the dislocation point and compared to reference sensitivity of HSR. Then there must be a conclusion of the influence of PTL on HSR or lack of such influence.
Keywords: Electromagnetic compatibility, high-sensitivity radars, overhead transmission line, industrial interference, broadband radio interference
Informatics, computation engineering and management
System analysis, control and data processing
We consider the problem of choosing the optimal alternative options. Selection is based on aggregation of criteria preference when weighting criteria importance coefficients are variables. Preferences by criteria are set a numeric evaluation of alternatives, and the criteria scale may be non-uniform. This article describes a technique developed by the authors consistent aggregation of criteria preferences, taking into account the importance of criteria that enables ranging alternatives by the preference and / or make a choice of optimal alternatives.
Of particular interest is the method of calculating the variables of criteria importance coefficients based on the preferences of the person receiving the decision maker (DM). In the process of dialogue with decision-makers identified vector estimation equivalent alternatives, which are then approximated by a curve of indifference. Previously developed algorithm allows you to find the constant coefficients of the importance of criteria by conducting approximation points equivalence alternatives straight indifference. This article points the equivalent alternatives approximated curve, which allows to take into account the preferences and decision-makers of the importance coefficients can vary with changes in the alternatives assessment.
The algorithm is demonstrated by the purchase of passenger aircraft aviation transport company. In the example we have assumed that when choosing aircraft economy class the most important are criteria such as price, reliability of operation, the cost of after-sales service.
Keywords: decision-making, multi-criteria choice, preference relations, ranging, aggregate preference, majority graph, criteria importance coefficients, equivalence-indifference points
Computing and control systems elements and units
The paper describes high-performance hardware controller development. The designed device allows to implement FDAL—A aircraft function and provides reduce of the development and certification costs.
Designed controller consists of the unique hardware-only platform and set of hardware-only applications. Each of application implements specific algorithms so the whole device performs the assigned objectives.
The platform architecture based on the reflective memory concept. That means the of virtual common memory for all application, and specific strictly determined memory exchange algorithms.
Each application represents by hardware module performs the task exclusively assigned to it. The platform has ability to control some equal applications.
Designed controller architecture has the modular-system roots, that aims to excellent scalability and flexibility characteristics and allows to implement new functions without the existing functions implementation modification.
The controller development is divided to two independent tasks — platform and application development. After that the IMA integration in performed. As a certification approach the task-by-task certification method (as described in DO-297) is suggested.
Keywords: Controller Architecture, Central avionics computer, integrated modular avionics
Mathematical support and software for computers, complexes and networks
Logical model of the automated system statistical rating assessment of quality students’ performance
The article discusses the logical model of the automated system of statistical rating assessment of the quality of students’ performance. University educational process model, which is automated by authors’ software, has been described. System architecture is presented. Information system is based on 1C:Enterprise technical platform.
Authors have developed a formula that defines student rating by session. Then researchers have identified the limitations of the 1C:Enterprise platform standard capabilities for accelerating calculation of student rating by session, which are defined by this fomula. The article mentions the features of implementation of 1C:Enterprise technologies in information system development. After this, authors have suggested their own ways of accelerating report generation through the use of new aggregates. System data storages have been presented as ER diagrams.
The old and the new structures of queries that calculate student rating by session have been presented by schemes. The practicability of the described approach has been proven by computational experiment. Researchers have compared the time required to execute the old and the new queries. The testing has been based on information about performance of real students from the Faculty of Applied Mathematics and Physics of the Moscow Aviation Institute. There are 5934 records in testing tables. Computational experiment results have been measured twice. At first, the queries have been executed without cache influence. Secondly, the queries have been executed with cache influence. Without cache influence, it took 7.25 times less time to execute the new query using aggregate suggested by authors in comparison with the old query. With cache influence, the new query using aggregate suggested by authors has been executed 3.77 times faster than the old query.
Results of this research can be used in automated rating system or information system for educational process automation that are based on 1C:Enterprise technical platform.
Keywords: information system, database architecture, aggregates, rating system