65 выпуск электронного журнала «Труды МАИ» является тематическим и содержит 40 научных статей. Статьи были подготовлены на основе докладов, представленных на ХI Международной конференции «Авиация и космонавтика — 2012».
В работе конференции приняли участие учёные, специалисты, преподаватели, научные сотрудники, аспиранты и студенты из более чем 76 предприятий и образовательных учреждений аэрокосмической отрасли.
По шести научным направлениям (авиационные системы, ракетные и космические комплексы, энергетические установки и двигатели, информационно-телекоммуникационные технологии, экономические проблемы аэрокосмического комплекса, математические проблемы в аэрокосмической отрасли) было заслушано более 200 докладов по актуальным проблемам развития и практического применения технологий в задачах управления авиационными, ракетно-космическими, техническими и социально-экономическими системами.
Издание данного выпуска будет интересным для тех, кто занимается изучением высоких технологий в аэрокосмической отрасли.
Mathematics. Physics. Mechanics
Preliminary assessment of stress-strain behavior is an important stage in design of any aircraft structure. Such assessment allows determining the first approximation of geometrical parameters of the designed structure elements already at the stage of its development. The more accurate the methods of stress-strain behavior assessment are, the lower are the costs of the subsequent design adjustments, which are implemented on the basis of the structure test results.
Design calculations of composite laminate structures are carried out by mainly using composite laminate macromodels, which are based on the theory of laminated anisotropic material, and various finite element models. The main role of the finite element models in this calculation consists in determining the effective stress. To obtain the solution in the first case an assumption is made that the deformations are equal and constant along the packet thickness. In the second case it is possible to construct a composite laminate model, which would take into account the interlayer and interfacial interactions between the composite laminate components. However, in this case the required computing capacity grows manifold directly proportional to the number of layers.
The goal of this research is to develop the method of analysis of stress strain behavior of any composite laminate packet in irregular zone of typical airframe structures. This is attained by creating a special mathematical macromodel for numerical analysis of the deformation of an arbitrary laminate composite packet, which allows for possible movement of the layers relative to each other with taking into account the shear stiffness of the binder.
Only two-dimensional stress state is considered in this study. An assumption is made that the interlayer space in a composite laminate packet is filled exclusively with the binder, the mechanical properties of which are isotropic. In the framework of the developed model a multilayer laminate composite packet, which actually consists of N monolayers with hM thickness, is considered to have N orthotropic lamina with hK thickness and N-1 binder layers with hC thickness. Each orthotropic laminae in the model is considered as a composite monolayer with a somewhat higher percentage of fiber content. The binder in the model is considered to have isotropic mechanical properties.
Thus it is assumed that the packet consists of layers of 2 different materials. The interfacial connections are considered ideal, i.e. the deformations are constant along the materials interface. It is also assumed that composite monolayer can only be in two-dimensional stress state, while intermediate binder layer can be in three-dimensional stress state with the exception of longitudinal deformations along the Z axis. Therefore, the possibility of occurrence of shear deformations γXZ and γYZ and, subsequently, shear stresses τXZ and τYZ. in the intermediate binder layer is not excluded from consideration.
The problem is reduced to the determination of the strain and deformation of composite layers according to the laws of the classical theory of elasticity of a laminate anisotropic material. For intermediate binder layers the deformations (including shear deformations) are determined first, the tangential shear, normal and equivalent strains are determined afterwards.
Interlayer shear deformations are defined by solving the equations of strain compatibility for the intermediate binder layer. This is done by using the dependence of the longitudinal deformation within the binder layer on the coordinate along the Z axis (boundary conditions are assumed as equal to zero):
where ε l(2) and ε l(2) are the deformations of the adjacent layers 1 and 2.
A calculation of a hypothetical loading case was carried out to investigate the capabilities of the methodology and analyze the results. A 40-layer composite laminate packet was considered. It was assumed that a certain load is applied to it. The load acts on a certain number of the upper packet layers (loaded layers).
The dependence of the layer and interlayer deformations on the coordinate along the packet thickness shows a strongly pronounced inverse proportionality. Interlayer shear deformations tend towards zero with greater intensity. Such dependence is most pronounced for the packet, which is reinforced in only one direction.
The shape of deformation distribution in the layers is independent from the amount of the applied load, the loading condition and calculation pattern. This means that there is a certain invariant characteristic of the deformation of the composite laminate packet, which depends only on the structure and properties of the packet. This allows assessing the stress-strain behavior of such packet at the stage when the load itself and loading condition are unknown.
It is necessary to gradually increase the thickness in the irregular zone to enable a more uniform loading of the composite laminate layers. However, based on the obtained solutions for the interlayer deformation it is possible to conclude that the interlayer shift directly depends on the size of the transition zone. Therefore the problem of determining the optimal size of the transition zone emerges. The optimal zone should allow gradual loading of the layers without exposing the interlayer binder to dangerous strains.
If there are shear stresses between the layers, they usually substantially prevail over normal ones. Thus delamination calculation can be based on the shear strength of the binder material. However, creation of an integrated strength criterion may be required.
There is a significant increase of the interlayer deformations in areas where the load is transferred from the layer with reinforcement angle 90° to the layer with reinforcement angle 0°. This is caused by the fact that the difference in stiffness of these layers is too big. When the load is transferred from the layer with reinforcement angle 0° to the layer with reinforcement angle 90°, a reversed interlayer effect can be observed, which consists in small values of the interlayer deformations and strains.
Keywords: composite material, stress-strain behavior, irregular zones, interlaminar shift
Demonstration of graphics processors usage in molecular-dynamic simulations.
Graphics processing unit (GPU) was originally developed for rendering real-time effects and graphical data in computer games. Now manufacturers provide a general purpose development kit. As an example, Brenner's potential is used to simulate carbon systems. To quickly perform the calculations of the equations, the following algorithms of parallel computing are used:
Mesh motion model; parallel integration; define hash function
Methods of scan; parallel potential computing
Results show that the usage of GPU decreases the time of simulation from days to a few minutes with less power consumption. General speed acceleration for optimized algorithms for NVidia Quadro 4000 graphics card was about 300 times in comparison with Core 2 Duo 2.6GHz:
GPU provided ~x10 acceleration,
Cellular flow model ~x10 acceleration,
The separation of the interaction potential of the individual parts ~ x3 acceleration.
185 microseconds are consumed for calculation on hardware Intel Core i3 (4 cores), 2.93GHz, 4GB RAM, nVidia GeForce GTX 480 at each step. In long-term calculation, 3 minutes of machine time were spent to simulate the molecular dynamics of one nanosecond of the "life" of the carbon nanotube.
The present study provides a starting point for further research in the molecular dynamic modeling of hydrocarbons. The software made gives an opportunity to research new undiscovered structures.
The research has proven to be useful in structuring data in molecular dynamics and computer testing on graphics units. This is a notable and promising side-effect of the exploratory studies, at least from an instrumental point of view.
Keywords: graphics processing unit, videochips nVidia, molecular-dynamic modeling, nanomaterials, buckyball
This paper presents a method of thermal residual stress calculation arising in composite caisson constructions after the manufacturing process. It is necessary to examine the influence of temperature on bulk integral constructions.
There are various fabrication techniques employed by the composites industry. The resin transfer molding (RTM), infusion, prepreg technology are several methods of integral construction producing. In this research prepreg technology is used.
Two main criteria influence the selection of prepregs for a particular application: performance and cost. The advantages of using prepregs are lower fabrication cost, reduced number of parts, control of fiber content, reduced energy consumption, good mechanical performance (tensile, stiffness, corrosion, good ageing, repair)
It is possible, for example, to apply the theoretical research work to manufacturing, that allows to improve the quality of finished product. Applying theory helps to reduce cost and minimize post processes such as finishing and handling.
The present study provides a starting-point for further research in the manufacturing sector.
This is the first research paper examines the influence of temperature on bulk integral constructions that leads to the structural warpage.
Theoretical value is development of the design and calculation methodology for integral constructions. This research has a practical use. Practically, this technique can be used in the design of real constructions such as airplane wings, horizontal and vertical tail assembly.
Keywords: composite material, thermal deformation, deflection, caisson, integral construction
The paper deals with the solution of pure bending of a rectangular beam of D16T material at constant temperature loaded with a constant bending moment. Research of the construction for creep and long-term strength are considered. A comparison is provided of the two methods for the problem solution based on the numerical results, as well as a comparison of the numerical solution with the experimental data.
The numerical calculation problem is solved using the equations of the energy variant of the creep theory, as well as the method of solution continuation with respect to a specific parameter and the best parametrization. The problem is being reduced to the solution of ordinary differential equations. The fourth-order Runge–Kutta method was chosen as the numerical solution method. By using these two methods of solution, creep curves were obtained, as well as the value for the long-term strength of the material.
According to the results, the following conclusions were made:
- A quite satisfactory similarity was found between the calculated and experimental data for the value of the curvature of the beam, which confirms the choice of defining equations in the energy form to describe the creep of beams until the destruction;
- The method of solution continuation with respect to a specific parameter and the best parametrization can be used for research long-term creep strength. The method of solution continuation with respect to a specific parameter and the best parametrization allows the integration step to be increased, reduces the number of steps to find the independent variable and the computation time, compared with non parametrized equations.
The method of solution continuation with respect to a specific parameter is first shown in this work, as well as the best parametrization of the problems of the creep theory. Obtained results and considered methods can be widely used in mechanical engineering, aviation and other high-tech industries.
Keywords: creep, destruction, specific energy scattering, damage parameter, beam bending value, solution continuation with respect to a parameter, parameterization, the best parameter, ordinary differential equations
Aviation technics and technology
To create and research the dynamic model of the helicopter. To simulate the processes, which occur under operation conditions. To determine the requirements for the dynamic model components. To study and test the technologies of modeling and research with ANSYS and MSC.ADAMS software products.
The dynamic model of the helicopter is a large assembly based on the modal component technology. Operation conditions were modeled as a transition process. The modal components were built with the help of finite element analysis (FEA) in ANSYS. Development and research of the dynamic helicopter model as a large assembly was carried out in MSC.ADAMS.
The research allowed obtaining force factors in the nodes of the dynamic model, vibrations and movement of the helicopter and its interaction with the airfield. Modeling shortcomings were identified.
An incomplete helicopter model with incomplete and simplified component models was developed. Thus the research results are of an experimental nature and can serve as a basis for further investigation.
The study allowed obtaining knowledge and practical experience of developing the entire dynamic helicopter model and its components. The directions and fields of further work were defined. An understanding about the technologies of modeling within ANSYS and MSC.ADAMS environments was obtained.
Keywords: dynamic model, helicopter, fuselage, landing gear, modal component, transportation vehicle modeling, transition process, landing, modeling technology
The paper addresses questions of improvement of aviation crew protection from shock overloads.
The paper analyses the possibilities of improvement of pilot seat ergonomics and its influence on pilot safety in case of a crash landing. It focuses on application of ergonomic adaptability principles for improvement of anti-g protective systems.
The main principles of load absorption by self-adjusting elements of pilot seat liner are adduced and considered. Main shock overload cases (such as crash landing) and their characteristics are identified. Comparative analysis of load distribution for various shock overload cases is made for traditional and adaptive anti-g protective systems.
Taking into account the anthropometry of a particular pilot in protection system design allows to significantly improve the ergonomics of aviation crew workplaces. Thus anthropometric data and data on crash landing accidents should be used for development and application of the adaptive self-adjusting structures (the adaptive pilot seat liners – “the adaptive lozhement”). Ergonomic individualization on the basis of adaptive seat liners will allow improving anti-g protective systems due to formation, support and retention of an optimal backbone shape and uniform distribution of loads throughout the contact area.
The current study provides a starting point for further research in the field of protection against aircraft landing shock on the basis of experimental and constructive methods.
The design of the adaptive pilot seat liner and its functioning principle are patented. Active systems of protection against landing shock with the help of adaptive and individual panels are suggested on the basis of these patents. Such systems form a balanced body position and safely retain it during the time of an impact. They also ensure the rational direction and metered transfer of impact striking forces and loads onto the pilot’s skeletomuscular system.
Keywords: ergonomic adaptability, impact accelerations, abort landing, anti-g protective systems, seat, helmet
The paper aims to investigate the phenomenon of the shift of aircraft aerodynamic center along the incoming air flow, which occurs upon the transition of the aircraft to supersonic speeds within the given Mach range. The influence of the shift on aircraft stability, controllability and maneuverability is also examined. The paper seeks for ways to reduce the adverse effects of aerodynamic center shift (ACS) and retain the stability (instability) of the aircraft at the preassigned level.
The paper proposes structural measures for addressing the problem and uses a heuristic research method. It is supposed that there is a structural capability to shift the canard along X axis. Thus functional dependencies of aerodynamic center position upon the flight speed are constructed for various canard positions. Based on this data it is possible to build a functional dependency of canard position upon the speed, which would help to decrease adverse effects of aerodynamic center shift (ACS). This idea is proven mathematically.
Proper change of the canard position along X axis during acceleration provides for a static position of aerodynamic center. This in turn helps to retain the stability (instability) of the aircraft at the preassigned level.
The present concept provides a starting point for further research in aerodynamics and aircraft design. Its elaboration requires further investigation.
The proposed concept could be useful for supersonic aircraft design. Due to the lack of research on the load factor change during the canard movement, which could be potentially dangerous for human pilots, the presented concept could be quite useful for the design of unmanned aerial vehicles (UAV).
The problem of retaining aircraft stability, controllability and maneuverability at supersonic speeds within the given Mach range remains open for more than 50 years. The presented concept aspires to solve that problem.
Keywords: aerodynamics, aerodynamic center, aircraft stability, aircraft controllability, aircraft maneuverability, supersonic speed, canard
The problem of a robust trajectory estimation for a maneuvering aircraft from the range and direction cosine measurements is studied in account for unknown parameters constraints.
The problem of aircraft trajectory estimation is studied in the minimax framework. Using the ellipsoidal constraints on the acceleration vector, the minimax formulation of the estimation problem is obtained. The numerical algorithm designed for trajectory estimation is based on usage of the semidefinite-programming solvers implemented in MATLAB.
The estimation algorithm is designed on the basis of the convex optimization theory. The efficiency of the obtained solutions is illustrated by the means of computer simulation.
The designed estimation algorithm might appear very efficient if the number of measurements is too few or the useful signal model is specified by large quantity of unknown parameters.
The minimax formulation of the estimation problem is reduced to the convex program with a linear objective and LMI constraints (LMI — linear matrix inequality).
The minimax Formulation of the estimation problem is reduced to the convex program with linear objective and LMI constraints (LMI-kinear matrix inequity).
Keywords: observation model, minimax estimation, robust estimate, ellipsoidal constraints, semidefinite programming
The paper aims at conducting numerical studies of the effect of triangular protrusion on the aerodynamic characteristics of seaplane wing.
The research was carried out with the help of a numerical flow calculation method by using ANSYS Fluent 14.5 software package (license number 670351).
Observations of the typical planform of the birds’ wings and analysis of the possible positive influence of the vortices on the wing aerodynamics have inspired the usage of a triangular protrusion for the wings of modern seaplanes.
A series of numerical calculations has been carried out with the help of the ANSYS Fluent computational fluid dynamics software system to determine the total aerodynamic coefficients and model the flow pattern in the vicinity of the wing. Calculations confirmed the positive effect of the triangular protrusions on the aerodynamics of a seaplane wing. The wing drag was reduced significantly. The value of aerodynamic efficiency was increased by more than seven units.
The results of the research can be used in seaplane aerodynamics.
The paper proposes a new wing planform shape. In the proposed shape the triangular protrusion plays the role of a vortex generating element, the use of which allows improving the aerodynamic characteristics of the seaplane wing significantly.
Keywords: amphibious aircraft, bird wing, wing with triangular protrusion, the Reynolds-averaged Navier-Stokes equations, turbulence models, aerodynamic coefficients
Space technics and technology
This article presents the operation results of the small satellite of scientific and experimental goals – the “MiR” satellite, which was create for testing a number of JSC “ISS” engineering developments and its partners.
The small satellite “MiR” based on the unpressurized unified space platform “Yubileyniy”. The Lifetime of the small satellite is one year. The mass is 60 kg. Structurally the satellite consists of the unpressurized hexagonal equipment module and three transversal honeycomb panels – upper, middle and lower. The upper panel contains the payload, platform subsystems equipment is installed on the middle panel and the magnetic-gravitational attitude determination subsystem is located on the lower panel (for 3-axial orientation of the satellite). The solar arrays panels (SA) are mounted on the outer surface of the equipment module.
According to the working-out results of devices installed on the “MiR” satellite there is a
decision for their further use in the series satellites developed by the JSC “ISS”.
The experiments performed on-board the “MiR” satellite provided the information and the base ground for the new technical level further development of the satellites which are created in the JSC “Information Satellite Systems” named after academician M.F. Reshetnev”. A part of experimental devices for the “MiR” satellite is manufactured with the participation of students and researchers of the Siberian State Aerospace University (the SibSAU) which is in close cooperation with the JSC “ISS”. Thus, one more task which was implemented in the “MiR” satellite creation, is improving the actual forms of educational and project-and-team preparation of specialists for the JSC “ISS” on the basis of the specialized institution – the SibSAU.
Keywords: small, space, satellite, experimental, scientific, mir, results, ISS, MKA, yubileyniy
Nowadays Air Revitalization and Monitoring Systems (ARMS) service on board of the International Space Station (ISS) has features:
Every ARMS operation is not connected with other systems;
ARMS performance depends on Off-Normal Situation (ONS), deviations of the parameters in other systems and on-board computer failures;
ARMS performance information is obtained partially, without elaboration and interpretation.
Thus, an adequate valuation of ARMS is complicated and ONS risks are increasing, that influence on the system resource. Therefore, an integrated approach to service of existent and being developed ARMS is proposed. It can provide:
Maximum ARMS operation data acceptance, elaboration and database creation. It will allow:
to provide a more complete estimate of the ARMS parameters and its components;
to predict the technical condition of ARMS performance;
to identify and localize ONS at early stages of development.
ARMS operation methods changing that have to consider:
the impact of parameters of other systems and ONS to ARMS operation;
the impact of the ARMS parameters and ONS to the performance of other systems.
ARMS operation ideology changing with a view to:
minimize the impact of on-board control system ONS to ARMS;
change the algorithm of ARMS operation.
ARMS manual operations reduction with a view to
decrease crew’s working time;
minimize the impact of the "human factor".
ARMS connection to additional equipment. It will allow:
to provide an opportunity to eliminate failures and ONS in ARMS;
to increase the level of safety of the ARMS operation;
to increase the ARMS operational life.
This integrated approach affords:
realize in full the ARMS potential on board the ISS (including increased system resource);
identify areas for further ARMS modernization.
Each component of the integrated approach is shown by examples of systems operation on board of the ISS, mainly Russian electrolysis Oxygen Generation System (OGS) "Electron-VM". A coefficient of obtaining information about system’s parameters is described and the model of data collection is proposed.
Russian trace contaminants removing system for the ISS was examined in this paper. Based on these studies, a statement of the problem of integrated approach to this system was given.
The same method was used in the Russian OGS "Elektron-VM" operation on board the ISS. As a result, the Technology Block (TB) № 009 of the "Electron-VM" in 2006-2011 had been working 1265 days (≈ 3,5 years) until a failure appeared. Previously, the maximum non-failure operation time was 456 days for TB № 005 in 2002-2005. (TB resource is 365 days and its weight is 160 kg).
Keywords: operation, integrated approach, the international space station, air revitalization and monitoring system, oxygen generation system "electron-vm", coefficient of obtaining information, contaminant
Blood is a diagnostically important biological fluid. From a physical point of view it is a suspension, where the liquid component — blood plasma and the solid component — formed elements, characterized by certain concentration, shape and size. Long duration space flight (SF) can lead to change of those parameters and some of them can be irreversible. So it is necessary to monitor the cellular composition of blood for timely preventive measures.
Work with liquid mediums under conditions of SF is complicated because of such factor as weightlessness. Invasive (i.e. with violation of skin integrity) sampling of biological material from crew members for the subsequent analysis also contains the risk of infection because an artificial closed ecosystem in a spacecraft is extremely favorable for growth and reproduction of various microorganisms.
In addition the supplies used during operation of the equipment require certain conditions of storage, have a limited shelf life and their additional delivery on board can be untimely.
All the above-stated facts prove the feasibility of non-invasive methods for the blood composition research.
For practical application of non-invasive methods allowing to assess the cellular composition of blood it is necessary to analyze such aspects as the use of this method under space flight conditions, as well as functionality and diagnostic value of the used equipment.
The purpose of this study was to consider possibilities of high-frequency Doppler Ultrasound for noninvasive research of the blood cellular composition under the SF conditions.
Currently the Ultrasound Method (US) based on the Doppler Effect is used on the ISS for the study of small (up to 1.5 mm in diameter) blood vessels. The studies carried out by authors earlier have shown that this method can be used in microgravity to determine the cellular composition of blood.
Enhancing the functionality of diagnostic equipment is achieved by improving not only the hardware but also software components. Records in digital signal processing (DSP) of the so-called "secondary effects" combined with an analysis of the amplitude spectrum and baseline (before flight) parameters of blood cellular composition allow to characterize shape, size and number of formed elements.
Simulation model of the research object is implemented with the help of MATLAB 7.0.1 environment. The model is based on the concept of representation of blood different formed elements in the form of clouds scatterers with different density, position of the mass center and average size of the particles. Block of DSP algorithm for the analysis of the amplitude spectrum is based on the sphere diffraction equation modified for set of scatterers and solved in an overdetermined system of equations.
Requirements for the hardware of ultrasound equipment were set according to the results of simulation. In particular, the minimum clock frequency of the ADC and the frequency range of ultrasound sensors are determined.
The algorithm of research execution is offered with taking account of pre-flight unit to ensure the consideration of the individual characteristics of the astronaut’s microcirculatory bloodstream. For this purpose it is necessary to assess vascular reactivity by the ultrasound method, to conduct the general blood test and then non-invasive determination of cellular composition of the blood. Research aboard manned spacecraft should be conducted in two stages: first, evaluate the type of blood flow in the smallest vessels measuring potential contribution of the "secondary effects" and only then carry out noninvasive study of the cellular composition of the blood.
The purpose of this study was to consider possibilities of high-frequency Doppler Ultrasound for noninvasive research of a cellular composition of blood under the SF conditions. Currently the Ultrasound Method (US) based on the Doppler Effect is used on the ISS for the study of small (up to 1.5 mm in diameter) blood vessels. The studies conducted by authors earlier have shown that this method can be used in microgravity to determine the cellular composition of blood. Enhancing the functionality of diagnostic equipment is achieved by improving not only the hardware but also software components. Records in digital signal processing (DSP) of the so-called "secondary effects" combined with an analysis of the amplitude spectrum and baseline (before flight) parameters of cellular composition of the blood allows to characterize shape, size and number of formed elements. Simulation model of the research object is implemented in the environment of MATLAB 7.0.1. The model is based on the concept of representation of different formed elements of blood in the form of clouds scatterers with different density, position of the center of mass and average size of the particles. Block of DSP algorithm for the analysis of the amplitude spectrum is based on the equation of diffraction on the sphere, modified for set of scatterers and solved in an overdetermined system of equations. Requirements for the hardware of ultrasound equipment were set according to the results of simulation. In particular the minimum clock frequency of the ADC and the frequency range of ultrasound sensors are determined. The algorithm of research execution is offered, consisting of pre-flight unit to ensure the consideration of the individual characteristics of the astronaut’s microcirculatory bloodstream. For this purpose it is necessary to assess vascular reactivity by the ultrasound method, to conduct the general blood test and then non-invasive determination of cellular composition of the blood. Research aboard manned spacecraft should be conducted in two stages: first, evaluate the type of blood flow in the smallest vessels measuring potential contribution of the "secondary effects" and only then carry out noninvasive study of the cellular composition of the blood.
Keywords: analysis of blood, space flight, noninvasive methods, ultrasonic diagnostics, the mathematical model, a peak spectrum
Since the beginning of researches of a near-earth space use of systems of remote sensing of Earth received broad application. The purposes of use of such systems is receiving a complete idea of Earth and processes passing on its surface, in the atmosphere, the hydrosphere, an ionosphere, a magnetosphere, etc. As shows experiment, use of remote-sensing instruments of Earth allows to solve a number of various tasks: from weather forecasting before forecasting of emergency situations. Due to the increase in number of consumers of this information, now there is a process directed on creation of multipurpose satellite systems of remote sensing of Earth, consisting of several spacecraft’s.
This work is devoted to development of program software, for the parametrical analysis and optimization of planning of target functioning of space systems of remote sensing of Earth. Efficiency of use of such systems depends on number of spacecrafts, their orbital parameters, characteristics of the onboard equipment, influence of factors of environment, etc. Limited opportunities for receiving, storage and operational transfer of large volumes of information of Earth received as a result of remote sensing cause need of the solution of a problem of a choice of the optimum design parameters meeting all set requirements and restrictions.
For an assessment of efficiency imitating modeling of functioning of satellite systems of remote sensing of Earth, for the purpose of a choice of the best option by the put criterion was carried out. he first stage of work was development of the concept of the automated program complex, and also development of the software for a various type of the analysis of systems of remote sensing of Earth. At this stage the program interface was developed, modules with various models are developed for an assessment of efficiency of functioning and as debugging of work of a program complex is made.
Carrying out the analysis of functioning of various satellite systems was the second stage of work. The detailed analysis of functioning of 3 satellite systems of remote sensing of Earth was carried out.
Result of the performed work is the program complex, allowing to carry out modeling of functioning of satellite systems of remote sensing of Earth, and also results of the analysis of some systems of remote sensing of Earth.
Keywords: space assets, earth observation systems, special on-board equipment, parametrical analysis , modeling, optimization, special software, estimation of the system efficiency
Some problems dealt with control of ionosphere modification under powerful electromagnetic waves produced by ground based heaters are discussed. The interaction between powerful electromagnetic waves and ionosphere leads to ionospheric modification. It occurs a number of effects of great importance, e.g. remote territories monitoring, underground probing, location and communication systems influencing. Therefore the problem of ground-based-heater-activity monitoring is considered in this paper.
Some ways of space system arrangement for HAARP heating facility monitoring are suggested. HAARP heating facility is the most powerful and technically equipped heater. Main investigations it provides are of no public use. A satellite monitoring system could acquire a number of data about its activity a ground-based monitoring system is not able to obtain.
Satellite system arrangement for quasi-continuous monitoring of HAARP heater using high elliptic orbits.
A theoretical framework is proposed based on minimum-time-non-observation criterion. Using viewing angles for HAARP heater and involving the motion along the high elliptic orbit observation time for HAARP heater is obtained.
Eight satellites provide quasi-continuous monitoring of HAARP heater using high elliptic orbits. Satellite system based on high elliptic orbits can be used for night hours, when HAARP heater’s frequency is higher than 4,9 MHz.
Universal satellite system for direct quasi-continuous monitoring of HAARP heater cannot be arranged using only high elliptic orbits. The problem can be probably solved using low orbits or after installing a radar on high-elliptic-orbit-based satellites. Results obtained in this paper can form the basis for space system arrangement of HAARP heating facility monitoring.
Keywords: ionosphere, ionosphere heating facilities, space system for monitoring, high elliptic orbit
In the article a new type of space radiators is considered. These radiators are based on the radiative cooling of drip shroud of actuating medium, spreading in space between liquid droplet generator and droplet collector. The energetic opportunity of applying of liquid-droplet radiators for power systems is studied.
The problem is solved in two stages. The first stage is the search for the best structure of drip shroud. External factors, such as the smallest size used drops, thermophysical parameters of the working fluid, temperature drop on the liquid-droplet radiator are used for the calculation. The concept of the distribution function of the reradiation coefficient was applied for the calculation of the structure. The influence of external parameters on efficiency of best structure is studied. The second stage is the calculation of the relative influence on each other different elements of liquid-droplet radiator. Obtained in the first stage information about the structure of the drip shroud was used for the calculation. Basis of calculation is the reradiation coefficient computation of the different planes of liquid-droplet radiator. The impact of the reflected reradiation on elements of liquid-droplet radiator is evaluated.
The energy characteristics of liquid-droplet radiator are studied. The dependence of maximum heat dissipation of the liquid-droplet radiator from the external parameters is calculated.
Keywords: liquid-droplet radiator, thermal power
Aerospace propulsion engineering
When creating turbochargers important task is to predict the resonant stresses of rotor blades at the design stage, in order to minimize the risk of destruction in the work, due to the high level of dynamic stresses caused by uneven gas flow. At the moment, most of the existing methods for predicting the possibility of resonance in the GTE blades based on empirical evidence and some assumptions. To optimize the process of forecasting the level of resonant stresses a more universal computational method, closely linking gas dynamics and strength. One of these methods is the Fluid-Structure Interaction (FSI). The advantage of this method is no need to rebuild the geometric models and grids at each step of the calculation, resulting in a significant reduction of complexity.
The aim of this work was to develop a methodology for determining the level of resonant stresses blades during the design and results of numerical studies with experimental data. The technique is based on the analysis of the interaction of unsteady flow of gas flow and the blades of the impeller high pressure compressor. In this study, the distribution of pressure and temperature fields on the surface of the blade, obtained from CFD solver is passed to a strength. Under the influence of gas dynamic and centrifugal loads on the blade is deformed and the deformed geometry is CFD calculation. Model real behavior blades in the flow, which allowed for the excitation of oscillations in several forms.
The advantage of this method is no need to reconstruct the geometric and finite-element models at each step of the calculation, resulting in a significant reduction of complexity.
Analysis of the results of calculations and experimental data has shown that we have the following picture: the maximum stress recorded in the expected range of frequencies, the calculated stress values obtained are close to the experimental data, and frequency diagrams are qualitatively similar in nature. The quantitative discrepancy is explained by the results of the assumptions made.
Keywords: GTE, vibration stress, Fluid-Structure Interaction (FSI), unsteadiness, spectral analysis, Campbell diagram, frequency diagram
Results of unsteady flow simulation for 1½ model turbine stage are considered. For cases with unequal numbers of blades/vanes in adjacent rows (“unequal pitch”) a computation over multiple passages is required to ensure that simple periodic boundary conditions can be applied. For typical geometries, a time accurate solution requires computation over a significant portion of the wheel or full wheel. It require prohibitive computing resources and becomes problematical especially for aviation industry with hard regulated times of developing. In this case it is necessary to use some simplifications (change number of blades, geometric and gas-dynamic scaling, transformation of problem to 2D simulation), which may result in inaccuracy in developing, because this technique is not allow to correctly simulate interaction of blade rows with unequal blade pitch. A number of methods are now available that address the issue of unequal pitch while significantly reducing the required computation time. Considered here are a family of related methods (“Transformation Methods”) which transform the equations, the solution or the boundary conditions in a manner that appropriately recognizes the periodicity of the flow, yet do not require solution of all or a large number of the blades in a given row. This paper will concentrate on comparing and contrasting these numerical treatments. The first method, known as “Profile Transformation”, overcomes the unequal pitch problem by simply scaling the flow profile that is communicated between neighboring blade rows, yet maintains the correct blade geometry and pitch ratio. The next method, known as the “Fourier Transformation” method applies phase shifted boundary conditions. To avoid storing the time history on the periodic boundary, a Fourier series method is used to store information at the blade passing frequency and its harmonics. In the final method, a pitch-wise time transformation is performed that ensures that the boundary is truly periodic in the transformed space. This method is referred to as “Time Transformation”. The three methods are realized in ANSYS CFX v.14 solver. Verification of used technique and comparison of simulation results with results of full mesh simulation is also presented in this paper.
Keywords: unsteady flow, turbomachine, blade row, rotor-stator interaction, profile transformation, time transformation, Fourier transformation, 3D simulation
Study the possibility of using existing engineering design procedures (EDP)[1,2,3] assessment of the thermal state of the combustion chamber of liquid rocket engine (LRE) in relation to the rocket engine of small thrust.
The comparison of the calculation of results thruster with gaseous oxygen and gaseous methane, which the simulation process in ANSYS CFX, and the results of calculations by well-known methods are made. We consider two ways to determine the mixing flow with the wall layer. The first method is based on the calculation of the turbulent mixing flow with the wall layer by engineering methods of calculation for LRE of large thrust. In this method, the intensity of mixing depends on the chosen value of the constant coefficient K, varying from 0.05 * 10-2 ... 0.2 * 10-2. The second method is based on the use of ANSYS CFX for workflow of mixing ingredients without combustion by SST turbulence model with the value of the turbulence intensity equal to 5%.
We consider two ways to determine the level of heat flow and temperature of the wall. The first method is based on methods that are applicable for the calculation of heat flows for LRE of large thrust. The second method is based on application of the distribution ratio of the components along the wall with the data obtained in ANSYS CFX.
When comparing the engineering method of calculating the results of mixing and mixing flows ANSYS CFX we received a significant difference in areas of complete mixing. Thus, it calls into question the use of methods of calculation of mixing flow with the wall layer applicable to LRE of large thrust for the calculation of processes in the chamber of rocket engine of small thrust. Further study and correction values of K are required.
Calculation results for the heat flow and temperature level the outer surface of the combustion chamber two ways shows qualitatively similar values in satisfactory agreement with the experimental data. This proves the applicability in the calculations of any technique.
Keywords: rocket engine of small thrust, gaseous oxygen gaseous methane, engineering method for calculating, numerical simulation, fuel ratio, wall layer, film cooling, temperature of combustion products
Frequency characteristics of solid propellant rocket engine design elements.
Methods for estimation of natural frequencies of solid propellant rocket engine design elements.
To carry out the estimation of influence of solid propellant rocket engine design elements during the resonance interaction on variation value of pressure oscillatory amplitude in combustion chamber under the origination of pitching acoustic instability.
Within the solution of the assigned task there were developed two models of solid propellant rocket engine that allow to determine frequency characteristics of solid propellant rocket engine design elements at concrete periods of time. 1. Model of discrete mass with elastic dissipative couplings. 2. Model with distributed parameters. Solid propellant rocket engine systems presented as discrete mass with elastic dissipative couplings is to be divided into six subsystems of finding partial frequencies of its elements and it is come to matrix solution with the help of the following components: joint coordinates of motion, restoring forces, inertia parameters, constraining forces, dissipative forces and quasi-elastic coefficients. Second model doesn’t require the solution of practical issue regarding determination of solid propellant rocket engine frequency characteristics. In order to form this model (with distributed parameters) the complex solid propellant rocket engine system is presented as the thin-walled shell and thick-walled massif made of another material and it contacts with the inner surface of thin-walled shell.
As the result the set task is come to joint ratio integration of shell theory and three dimensional elastic theory subjected to specific conditions at surface to contact medias and other conditions. Verification of achieved results was done according to pilot testing with application of the modal analysis.
There were developed two algorithms of solid propellant rocket engine natural frequencies estimation: with the application of the point mass method and “distributed” model. Researching of the achieved models was carried out with the purposes to analyze their precision and complexity of their realization.
Determination of natural frequencies of solid propellant rocket engine is the actual for the estimation of operability of newly developed solid propellant rocket engines. This research displays that more complex but more precision algorithm is the “distributed” method. This algorithm allows to do detailed estimation of solid propellant rocket engine system dynamic parameters. Less labour and time-consuming algorithm is the algorithm for presenting the solid propellant rocket engine system as the discrete mass with elastic dissipative couplings. This algorithm requires the concrete attitude to set up of boundary conditions. Achieved algorithms can be used for estimation of influence of geometric and physics mathematic parameters of solid propellant rocket engine elements on the whole solid propellant rocket engine system amplitude frequency characteristic. In this case algorithm using discrete mass model with elastic dissipative couplings is applied on the initial stage of solid propellant rocket engine development and “distributed” model is applied for specification of received results.
Keywords: own frequency of fluctuations, self-oscillatory system, solid-fuel rocket engine, discrete mass method, method with distributed parameter
With the help of the suggested methods for researching dynamic tensions of compressors blades at resonant oscillations at high modes the area of occurrence and the subsequent development of fatigue cracks up to the final breakage can be defined. The problem of foreign objects distribution in the engine compressor has many aspects. Great complexity of processes and phenomena, variety of the factors at the same time operating and connected among themselves, often controversial complicate the full solution of this problem.
In the analysis of the reasons of blades destruction in operation and the identification of hazardous forms of oscillations it is necessary to analyze of the excitation forces frequencies (for probable harmonics) and range of their natural modes and frequencies of the studied blades.
From the nature of all the compressors blades fatigue failure it can be seen that all the blades regardless of their size and material are destroyed in a clearly restricted areas on the back, edges, end. The relative coordinates of the location of the cracks are approximately the same.
This indicates the general regularities of the blades dynamic loading andthe emergingtensionsin themat resonantoscillations.And the presenceof operationaldamageon the bladesdoes not influence on these regularities.
As we know fromsad exploitation experience,evengettingasmall portion ofthe destroying blade in the gapbetween the casing and the otherblades tips can leadto the titaniumfire.Obviously,the presence of manysuch fragmentsincreasesthis probabilityby several times and, at best, definitelycauses engine damage.
According to the results of the exploitation observation works the nature of the detected failures allows you to distinguish dangerous resonances and to determine the frequency and the excitation harmonics.
The main objective — revealing of the destruction reasons is achieved. That allows you to develop measures on suppression of defects.
Keywords: high pressure compressor, aircraft engine, compressor blades, fatigue failure, form of oscillation, maximum nominal strain
A general principle of operation and a brief history of the multicircuit direct-flow combustion chambers on solid fuels are revealed. An algorithm of using ANSYS software to create an experimental setup capable of modeling the workflow in the double-circuit combustion chamber of rocket-ramjet is engine is proposed. Since 1935, engineers have been developing technologies for hypersonic systems that can fly faster than the speed of sound in the atmosphere. Hypersonic systems would have many benefits. For example, a hypersonic missile capable of an average speed of Mach 5 could strike a time-sensitive target in short timeframe. One of possible way to achieve real hypersonic prototypes is using perspective schemes and a first step for that is 3D modeling. The scientific paper contain complete algorithm in which a real design are created from simple scheme. The main purpose of the research is to develop a scientific basis for designing small-sized double-circuit combustion chambers, which provides after-burning of primary combustion products of fuel in small gas vortexes. But, the present study provides basic findings. Further tests are needed. In this research were used software packages: ANSYS 14 and Solid Works 2012.
For research of the processes of combustion and mixing inside the model combustion chamber a software package ANSYS 14 (module CFX) is used. To create a solid-state model of the real design a software package Solid Works 2012 is used.
A general principle of operation and a brief history of the multicircuit direct-flow combustion chambers on solid fuels are revealed. An algorithm of using ANSYS software to create an experimental setup capable of modeling the workflow in the double-circuit combustion chamber of rocket-ramjet engine is proposed. Optimal expenses of components that involved in the process of mixture formation and combustion is obtained, the final geometry of the experimental setup and model is determined.
Keywords: forced air gas burner, adjustable mixing chamber, double-circuit, rocket-ramjet, ANSYS Fluid Flow (CFX)
Selection of high frequency ion thruster materials and development of manufacturing processes for critical structural elements.
This study traces the results of tryout technology development for manufacturing ion thruster critical structural elements: dome-shaped perforated electrodes made of carbon-carbon composite material and ceramic discharge chambers.
To manufacture units of corundum, the technology of hot high-pressure casting with thermally-plastic slurry is used. The technology for manufacturing units of silicon nitride comprises the following processes: unit formation by hot casting of a composite paste comprising silicon powder, corundum filler and a binder, and unit final formation in nitrogen environment by sintering the silicon nitride. For the electrode manufacturing a sandwich-type carbon textolite with shifted direction of each next layer relative to the previous one by 600 is used. The sandwich carbon textolite is covered with laminating surface layers consisting of carbon material of the felt type. The sandwich is compacted pyrolytically (by gas-phase saturation with pyrolytic carbon). Laser beam is used to form apertures in electrodes. A technological process for aperture making at the stage of carbon-filled plastic workpiece formation has been developed. For this purpose the bottom layer of carbon felt was formed to the metallic plate with pins placed in accordance with the aperture grid for electrode. The carbon fibers with needed linear density were laid in three directions into the grooves between pins. The obtained sandwich was impregnated with a binder and closed by a stamp. After that the carbon-filled plastic workpiece in pressed state was subjected to thermal processing. To check up behavior of the chosen materials in the real structure, experimental investigations were performed by using a thruster model operating within the wide ranges of power (from 30 W up to 300 W), flow rate (from 0.2 mg/s up to 0.9 mg/s), and frequency (from 1800 kHz up to 2100 kHz). We tested not only chambers, but different matching devices also
It was revealed experimentally that high frequency ion thruster parameters change insufficiently with the replacement of discharge chamber material by a cheaper ceramics.
As a result of the works performed it is possible to conclude that in our country the technology for manufacturing basic structural elements for high-frequency ion thrusters has been restored within a relatively short period of time. The new solutions for manufacturing electrodes of carbon-carbon composite material were tried out in view of the electrode perforation. It is shown that at the stage of thruster tryout it is possible to use cheaper silicon-nitride ceramics.
Keywords: structural materials for ion thrusters, electrodes, composite carbon-carbon material, discharge chamber, ceramic material
Theoretical engineering. Mechanical engineering
The purpose of this work is to develop a method to find the forces and stresses in the most loaded places of the wave gear with intermediate rolling bodies — areas of contact of rolling bodies with other elements of the gear, and find the dependence between stresses in these areas and gear geometric parameters based on analysis made by this method.
The method is to determine the deformation of circular spline while the wave generator and circular spline have stopped, and the separator has turned to some small angle. In this case, the rolling bodies and their areas of contact with a circular spline will be moved causing deformation of the circular spline. Since the circular spline obeys Hookes' law, the resulting forces can be found acting by the circular spline on the rolling bodies. These forces are then translated to the percentage distribution of loads in all contact areas, then possibly real forces and stresses are found. Strength criterion is the stress at the most loaded contact area. The method uses the following assumptions: a separator, wave generator and rolling bodies are considered absolutely rigid; friction is small in the contact areas of rolling bodies with other parts, hence there are no gaps in the gear.
A resulting mathematical algorithm for the strength calculation of wave gear with intermediate rolling bodies was compiled. Analysis of results of the calculations was made. A relation was discovered between the radius of the wave generator, the radius of the rolling body and the number of periods of the circular spline, when stresses in the contact areas are distributed more evenly, which allows to reduce weight and volume of the gear and increase durability.
The method developed can be used to calculate the strength of the wave gear with intermediate rolling bodies. Gears of this type have a number of advantages in terms of weight and volume compared to other types of gears, making them a high demand in systems where these parameters are critical, such as in aircraft actuators.
Keywords: wave gear with intermediate rolling bodies, stress analysis of wave gear with intermediate rolling bodies, stress distribution in wave gear with intermediate rolling bodies, contact strength
Automatic in-flight refueling of unmanned aerial vehicle (UAV).
This paper addresses the fly-by-wire system automatic control algorithm design for the in-flight refueling procedure of high maneuverable aircraft.
The main goal is to navigate and control UAV (during the docking phase of in-flight refueling procedure) so that probe will link up with the drogue mounted on the flexible hose trailing behind the aircraft-tanker. Practical probe and drogue autonomous in-flight refueling requires a robust relative navigation and control algorithm to be designed.
The design process of the control algorithm can be divided into three main parts. The first one includes linearization of UAV equations of motion for the typical values of airspeed and altitude when in-flight refueling. This can be carried out by commonly used linearization technique. The second part consists of linear analysis and design of the inner loop (angular velocity stabilization) control algorithm. The design process is based on the L1 adaptive control theory. In the third part, the linear observers and other components of outer control loop are developed. Feasibility and performance of the total system were demonstrated by simulation of unmanned refueling aircraft docking maneuvers with the non-stationary drogue of an unmanned tanker.
Results presented in the paper showed that the controller can enable precise in-flight refueling thanks to the new algorithm, allowing for real measurement errors, plant modeling errors, and disturbance.
Presented in this paper control algorithm may be used in a fly-by-wire systems of modern manned and unmanned aerial vehicles.
Keywords: fly-by-wire system, aerial refueling, docking procedure, wake vortex, observer
The main aim of this work is to provide a good base for the applicability of neural network inverse-adaptive scheme designed for spacecraft control.
The neural network inverse-adaptive schemes of various objects were modeled in the MATLAB software environment with subsequent conclusions about the quality of management and recommendations identification for further improvement.
There made some conclusions about fundamental suitability of selected scheme designed for control of spacecraft perspective.
The new algorithm for creation of neural network inverse-adaptive control system was developed. The recommendations for modernizing of management scheme were proposed in order to overcome the open-loop system.
Keywords: control, flight, compound object, neural network, inverse-adaptive scheme
Technical cybernetics. Information technology. Computer facilities
The new general method of context-sensitive probabilistic compression for measurement data is presented in the paper.
The main aim of designing the new method was an enhancing of stream-transmission efficiency for telemetry and monitoring systems at the cost of data compression.
These results are obtained by simplification and optimization procedures for generating a measurement data compression context and arithmetical coding application as well as computational resources minimization. The binary alphabet together with automatic choice of inverting or non-inverting probability ranges for neighbor bits are applied to arithmetic coding.
The binary implementation with range inversions makes it possible to generalize a compression approach for most measurement data representations: integer, signal, composed and real values. Lossless, lossy, and adaptive compression is also supported.
The proposed method is applicable for measurement data reduction before transmission in remote communication systems and can be helpful for the developers. The method advantages are high degree of reduction and low resource consumption whereas its disadvantages are the dependence from context and high exactingness to transmitting information in code.
The method is used in Out of Environment Control Hardware algorithms on GLONASS-M spacecrafts. The data was compressed by a factor of 5-10 to source size depending on structure of measured parameters. The method was also successfully tested for supporting power supply and heat regulation systems of GLONASS-M spacecrafts.
Keywords: telemetry, measurements, binary arithmetic coding, compression context, out environment control hardware, spacecraft
The study objects of this article are the production processes in aviation and space-rocket industry. The main attention is paid to the manufacturing flows in production systems. Simulation is considered as one of the methods of construction and research on manufacturing flows. In order to create a simulation model it is needed to carry out a serious and difficult work, which is sometimes more time-consuming than the process of construction and analysis of simulation models. The purpose of this article is the study of the processes, which precede to the creation of simulation model. This article presents one of the possible approaches to the development of manufacturing flows simulation methods. It is shown that the simulation model includes a set of different types models such as the product mathematical model, network product model, the network model of the processes, as well as the model of network resources used in the creation of the product. The approach is primarily designed for engineers, which are the main data sources on the production system. It is proposed to develop a simulation model in three phases, where the last one is actually the formation of a simulation model. Also it is needed to identify the data sources for the constructing simulation model. And finally, it is necessary to develope approaches for the construction of works complex general methodology, which is needed for the creation of manufacturing flow simulation model. In addition, the article gives information about software used for the simulation, provides a brief overview and fields of their application. The article will be interesting for the engineers involved in production systems design, for the manufacturing flow simulation engineers, as well as for the specialists participating in creation and management of industry production systems.
Keywords: simulation, manufacturing process, simulation software, network model
Parametres of reliability of the spacecraft;
Spacecraft’s performance evaluation expressed in taken images of the Earth surface area with the reliability;
Work out the imitating modeling models and algorithms of influence of onboard supplying systems partial failures and target equipment on parameters of spacecraft target efficiency;
In the article logical-and-probabilistic methods are used for the analysis of onboard systems operability, a method of imitating modeling and a method of statistical tests. The analysis of a statistical material foresees classification of failures concerning target operation of the spacecraft stand-by time. Construction of failures mathematical models is based on the construction of onboard systems failures trees. Construction of failures trees spacecraft of observation is based on the construction of onboard systems failures trees.
On the basis of algorithm for the estimation of shooting productivity, expressed by quantity of finished shooting objects of supervision, the algorithm for the estimation of shooting productivity evaluated by the size of the area.
Results of the conducted research are used at early design stages of the spacecraft. Research results can be used at early stages of onboard systems development and their parameters estimations.
Mathematical models of the onboard systems failures, algorithm of imitating modeling of influence of partial failures on parameters of a spacecraft’s shooting productivity and the corresponding software are developed. By means of the software it is possible to recreate the dependence of the shooting productivity on the spacecraft’s reliability parameters. Such relations allow estimating losses output effect from reliability level of the spacecraft. On the other hand, taking into account onboard systems failures, it is possible to set spacecraft reliability parameters norms.
Keywords: algorithm, the mathematical model, partial failures, the observation space vehicle
The purpose of the present paper is to consider the research results in the fields of creation of fail-safe systems of aircraft avionics, which are capable to automate the critical aircraft processes and to satisfy the requirements of airworthiness regulations, flight regularity, all standards for aircraft equipment as well as to minimize maintenance costs. It is shown that the architecture of such systems must meet the concept of integrated modular avionics (IMA).
The work has basically resulted in developing a comparison method for parameters values, that have passed over different interface computation paths, while the majority testing is performed for these paths. This method is based on a regression filter designed by the author. The statistics of multiple signals carrying any information of the parameter value is processed in the regression filter and compared with the value within confidence interval for the residual variance of the parameter regression. Any disorders in the path are shown to cause a change to the selected comparison criterion. The practical significance of the developed method is that its application in information processing systems for critical parameters (systems which failures cause emergency and catastrophic effects) allows sufficient fail-safety to be achieved to satisfy airworthiness and flight regulations.
In addition to the results mentioned above, the following points have been developed: the architecture of a fail-safe interface computer platform, the architecture of the IMA system, which subsystems are built on the platform developed in this work, the flowchart of the typical interface computer path. In addition to that, formulas for reliability performance calculation have been deduced for a sophisticated redundant system.
The reasons to develop aircraft equipment to the IMA concept are shown. The particular methods of IMA platform development and systems minimizing design and maintenance costs have been developed.
Keywords: system, avionics, interface computation path, architecture, IMA platform, unified, maintenance, costs, operation, redundancy
For the analysis of security incidents of university automated system (AS), it is necessary to proceed from not only the research methods used by intruders, but the identification of system properties allowing them to carry out their actions. Thus, the task of identification and evaluation of compromising information is araised. The concept of the information compromising AS, i.e. identifiable information that allow to find vulnerability and to use them afterwards, is a problem studied in this paper. It was shown that it is possible to separate several classes of threats realization in accordance with the considered types of vulnerabilities.
The first class is a class of expected threats, that can be attributed many relevant ways of threats realization, the second one is a class of possible, but unexpected threats – a lot of irrelevant ways of threats realization, and the third one is a class of unforeseen and, as a consequence, unexpected threats – there can be many extraordinary ways of threats realization.
The obtained results are the basis for the identification of vulnerabilities of different type AS, and as a consequence, compromising its security features. The results were used to develop proposals for reducing the vulnerability of information security AS of Moscow Aviation Institute, as a new type of problems never considered before for university-class AS.
Keywords: automated data processing system, vulnerability of the system, compromising information, information field, entropy
Algorithms and methods for automated digital image processing in the visible and infrared ranges obtained from the board of unmanned aerial vehicles (UAVs) searching for moving ground targets.
The superposition of infrared images with images in the visible range in the tasks of identification of moving ground targets from UAV`s board.
Purpose of the paper is development of complex algorithm of moving ground targets identification from UAV`s board. To achieve this purpose it is necessary to develop an algorithm that can operate under the condition of incomplete a priori information about the object of identification.
The main features of the algorithm are:
- universality of the algorithm (ability to recognize different classes of mobile ground targets);
- stability against affine corruption of image;
- operation in the near real time mode.
Image processing received from the UAV board becomes complicated by the following factors:
- onboard UAV video probe moves in space with the UAV, moreover, its spatial orientation can be changed by an operator with the help of a positioning device;
- video probe is affected by the vibration impact of different nature;
- environmental influence (rain, snow, fog, wind, etc.).
In this study the author used methods of mathematical modeling, computer vision, and the theory of probability and mathematical statistics.
The results can be implemented in solution of tasks of mobile ground targets identification. These tasks arise when UAVs are used for military purposes: for reconnaissance, for observation of a battlefield, for monitoring results of enemy toll under destruction fire, etc.
Usage of combined analysis of IR images can reduce almost 3 times the number of false alarms what was confirmed experimentally. It is also important to note that at this stage of research combined joint analysis of the infrared image along with image in the visible range is not aimed at the object type definition (it is defined whether an object moves or not). This approach allows for quick and efficient search of moving objects from the UAVs` board without detailed analysis of the object itself.
Keywords: pattern recognition, key features of the image, IR images, identification of moving targets
Radio engineering. Electronics. Telecommunication systems
Debugging and modeling of complex processing devices based on field-programmable gate arrays (FPGA) using specialized computer-aided design (CAD) programs can be a time-consuming process. Ground-based debugging complex (GBDC) is developed to accelerate the debugging of the FPGA designs based on custom hardware. The devices debugged by GBDC may include storage units with various interfaces and memory organization. At the same time GBDC array of storage devices consists of memory chips that have strictly defined structure and parameters and can’t be reconfigured or replaced afterwards. Therefore, it proposes to use some means for emulation of memory chips used by device being debugged. For this purpose the universal control unit for ground-based debugging complex storage array is developed and described in this paper.
The paper dwells on the control unit organization, its block diagram and functions of device components. The control unit is located between a device being debugged and the ground-based debugging complex storage array. The device being debugged interacts with the control unit as its own memory storage. In order to simplify the development process and further upgrade and reconfiguration the functions of the control unit are separated between three modules. The first one is a module operating with the device being debugged, the second one is a module operating with GBDC storage array, and the third module is to test GBDC storage array.
Thus, in the paper the basic requirements for the control unit are formed. Furthermore, the block diagram of control unit, the functions of its components and the communication protocols were developed. The results can be used for a further implementation of the universal control unit.
Keywords: ground-based debugging complex, universal control unit, emulator, fpga, storage array, march tests
The modern satellite communication systems such as «Yamal-200» and «Express AM3» consist of a set of satellites using the polarization multiplexing in a wide frequency range of C-band. Earth station antennas of such systems should have a level of cross-polarization isolation waves of circular polarization not less than 30 dB in the reception band 3.4 — 4.2 GHz and transfer band 5.75 - 6.55 GHz. Polarizers of antennas for these systems must provide a 90-degree differential phase shift with a deviation of not more than 2-3 degrees, but the lack of higher order modes, the occurrence of which leads to a deterioration of the polarization characteristics. The purpose to the present work is to develop a suitable polarizer for advanced satellite communication systems.
Polarizer consists of a circular 54 mm diameter waveguide and the dielectric plate. Sizing of polarizer elements is carried out by simulation using a computer program based on the solution of Maxwell's equations by the grid method. Dimensions are calculated to required desired approximation accuracy of characteristics and the level of cross-polarization isolation.
The paper presents the design of the polarizer and the results of calculations and measurements of cross-polarization isolation, VSWR for two frequency ranges, and the level of excitation waves higher type.
A prototype of wewideband polarizer for satellite communication systems with polarization multiplexing is developed. It has reduced frequency dependence of the differential phase shift and decreased excitation of higher wave modes.
Keywords: wideband polarizer, satellite communication systems, circular waveguide, dielectric plate, results of calculations and measurements
In this paper, the design of an ultra-high frequency (UHF) band microstrip patch antenna is presented. This type of antenna is offered to solve one of the important problems of antenna technology – the design of small-sized, low-profile on-board antennas.
For practical application of this type of antenna was considered the option to create a new antenna system, the spacecraft "Ionosphere", included in the space complex "Ionosonde", which is created JSC "Corporation VNIIEM" commissioned by the Federal Space Agency. The staff of the laboratory of antenna-feeder devices of JSC "Scientific Research Institute of Electromechanics" developed antenna system of the spacecraft "Ionosphere".
In this paper presents the main parameters of dipole antenna designed for on-board dual-frequency transmitter "Mayak 150/400" (radiation pattern, gain, operating frequency range, polarization, output power, etc.), which designed the layout of microstrip patch antenna 1:10 scale for testing the similarity of the electrodynamic model of the spacecraft "Ionosphere" in 1:10 scale at the operating frequency of 4000 MHz. Electrical characteristics of the layout of the microstrip patch antenna were also evaluated (standing wave ratio, radiation pattern).
From the obtained results it can be concluded that the use of microstrip patch antennas will solve the problem of the design of small-sized, low-profile on-board antennas.
Keywords: microstrip antenna, spacecraft, space, dipole antenna
Solution of high-frequency radar signal processing for adapting the system to the characteristics of the reflecting heterogeneous surface is one of the important problems of modern security radars. This paper deals with software and hardware solutions of the problem of adapting the system under complex correlated noise reflected from homogeneous underlying surface.
The hardware solution is based on the implementation of programmable gates setting up the timing of the receiving and transmitting modules. The software solution is based on a multichannel matched filtering algorithm using a low-pass or band-pass decimating filters. If the time-frequency structure of the received signal is changed, the structure of the processing system will be reconstructed automatically. This hardware and software solutions are applied to the radar «Orwell-R».
Supporting programmable waveform used in radar «Orwell-R» provides the possibility to solve new problems, such as the increasing of the range of the radar with a peak power restriction, the detection of small objects on the background of heterogeneous land surface realized by improving the selection to the Doppler frequency with complex signals, reducing the dead zone to detect nearby objects etc.
Currently, the programmable timing diagram of reconfigurable radars is a new direction in the radar design. This study represents a starting point for further research in the improving of the radar system efficiency. The new approach to the design and configuration of radar systems allows configuring the system according to the customer requirements and the characteristics of the protected object in real time using a programmable waveform and reconfigurable radar signal processing.
Keywords: radar, heterogeneous underlying surface, digital signal processing
The aim of the work was to develop mathematical model of aligning the interconnect elements in multilayer PCBs to ensure high reliability and improve mass and dimensions parameters of electronic modules of modern aircraft onboard equipment without increasing the cost of final products.
Solution of the research problems was based on the combined use of theoretical methods: the theory of expert evaluations, technological processes design principles, and probabilistic and statistical methods.
A new approach for calculating the pad size in multilayer PCBs of avionics and other critical equipment was proposed, allowing to define the probability of loose connections occurrence in production. A new pad shape was proposed for increasing the PCB trace area.
The results of this work are used for increasing the layout density of modern avionics with its reliability level sufficient for this industry and reduction of the production cost.
A refined mathematical model for calculating spatial alignment of the interconnect elements in multilayer PCBs was developed. The interrelation between the PCB pieces registration system during the pressing and final alignment error was defined.
Keywords: geometric stability, laminate, printed circuit board, interlayer connections, registration system, pad
To provide a methodology for multilayer armor design aimed at ensuring the required level of object protection from small-caliber ammunition up to 12,7x108 mm.
The paper proposes a mathematical model for estimation of energy absorption in armor layers and residual slug energy after armor penetration based on the data concerning armor materials, their physical, chemical and mechanical properties and geometrical characteristics. The model allows calculating various mechanisms of metal armor penetration as well as combining different materials into a multilayer structure. The simulation can be made for any bullet hit angle relative to the armor surface.
Various armor structural materials were used for testing the method: metals, alloys, composite materials made from carbon, glass, basalt, ceramics, polyethylene and aramid fabrics. The comparison of theoretical modeling results and experimental ballistic tests has proven the validity of the modeling methodology as well as its capability to optimize the armor weight.
The model implies that bullet slugs, which are made of thermo-strengthened steel or tungsten carbide, are non-deforming bodies. It also implies that submunition moves along the minimal trajectory within the protective plate volume.
The developed approach to the design of multilayer armor structures allows using a wide variety of materials with different properties and destruction behavior during the optimization of the structure weight. The proposed method also significantly decreases the time required for computation of armor penetration without reducing the accuracy of the obtained results.
Keywords: composite materials, armor, composite structures, aircrafts, weapons
The purpose of this work was to elaborate a mathematical model relating the adjustment for foiled laminate shrinkage to the copper foil and dielectric substrate thickness, which will allow to calculate the correction for shrinkage of the whole range of materials used in manufacturing.
The solution is based on the combined use of regression analysis and fundamentals of measurement tasks theory.
A general form of dependency of the necessary correction for shrinkage from parameters of PCB laminate was defined. The model was calibrated using ISOLA IS680-333 as an example. The proportion of unexplained variability in the variance of shrinkage correction has been evaluated.
The submitted mathematical model allows to forecast the correction for shrinkage of the whole range of base materials used in production using measurements from several samples. This approach results in a significant reduction in time and material costs of precision PCB production.
A mathematical model relating the adjustment for foiled laminate shrinkage to copper foil and dielectric substrate thickness, helping to reduce costs and to accelerate the introduction of new models of foiled laminate, was elaborated.
Keywords: geometric stability, laminate, printed circuit board, clad dielectric material, Computer-Aided Manufacturing (CAM)
Economics and management
To define methodological approaches to evaluate the competitiveness of aero engines (AE) in order to increase its adequacy.
To evaluate the competitiveness it is offered to apply the integral method as it takes into consideration different factors affecting the value of the former.
The topicality of the need to raise the competitiveness of the aero engine industry is emphasized. Some theoretical issues of establishing the definition of competitiveness of aero engines, main terms and approaches are given. The content of algorithm procedures for definition of competitive advantages of a given object (AE) is specified taking its features into account.
The methodological aspects of definition of the competitiveness of the research’s subject (AE) considered here serve as base for creation of a model of its evaluation and further analysis of the trend in order to establish an adequate mechanism for support of competitive advantages of an aero engine.
The listed methodological approaches may be applied to define the competitive advantages of one aero engine vis-à-vis another similar one.
The originality of this research lies in the integration of different approaches to the evaluation of the competitiveness of aero engines and the accentuation on its dynamics.
Keywords: competitive advantages, aero engines, evaluation of their competitiveness
To analyze the structure of the world space market of launch vehicles, depending on the distribution of classes over the years, and to propose possible ways of its development.
The paper provides a classification of launch vehicles based on their mass, in accordance with the classification which is determined by the market structure of space launch vehicles.
The analysis allowed us to determine that on the global space market there is a need for a new cost-effective, highly reliable launch vehicle that would be capable of launches small satellites into a sun-synchronous orbit and geostationary orbit. In order to create these missiles in a short time and with a minimal cost, it is necessary to find new technical, operational and organizational decisions.
Studyingof the export capability of industrial enterprises and identification of the areas for development can provide with an objectiveassessment of the impact of the structure and the volume of its exports on the total economic capability, in order to assess the dynamics, direction, and improve the efficiency of industrial enterprises in the domestic and foreign markets.
It is expected that the development of the company in global market will increase exports, improve the product and the geographical structure of export, the use of advanced forms of international trade and economic co-operation and, consequently, increase sales in overseas markets.
Keywords: plant facilities, export capability, space-rocket hardware, market analysis, competitiveness