Статьи журнала - Siberian Aerospace Journal
Все статьи: 151
Change in magnetoresistance in manganese chalcogenides MnSe1-XTeX from bulk to thin-film samples
Статья научная
The electrical and optical properties of anion-substituted antiferromagnetic semiconductors MnSe1-ХTeХ (0.1 ≤ X ≤ 0.4) in the temperature range 77-300 K and magnetic fields up to 13 kOe in bulk samples and in poly-crystalline thin films are investigated. Negative magnetoresistance was found in the MnSe1-XTeX solution in the neighbourhood with a Néel temperature for X = 0.1 and for a composition with X = 0.2 in the paramagnetic re-gion up to 270 K. A correlation was established between the spin-glass state and magnetoresistance for X = 0, 1 and 0.2. The opti-cal absorption spectra were measured in the frequency range 2000 cm-1 < ω < 12000 cm-1. A decrease in the gap in the spectrum of electronic excitations and a several of absorption peaks near the bottom of the conduc-tion band were found. Coexistence of two crystalline phases was found in polycrystalline films of the MnSe1-XTeX system by X-ray diffraction analysis. Resistance maxima were established in the region of polymorphic and magnetic transitions. A model of localized spin-polarized electrons with a localization radius varying in a magnetic field as a result of competition between ferromagnetic and antiferromagnetic interactions is proposed. In the paramagnetic region, negative magnetoresistance is caused by tunneling of spin-polarized electrons during orbital ordering.
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Characteristics of low thrust liquid-propellant rocket engines testing process
Статья научная
Low thrust liquid-propellant rocket engines (LTLPRE) are the main type of rocket engines for control systems of space aircrafts. The thrusters are able to work either in continuous or impulse regime, which is one of their main characteristics. The suggestion about engines` reliability should come from the results of tests which create real or greatly approximated to the real conditions. The development process of thrusters takes into a great account the problems of bench testing methodic, technical equipment of test benches for creating the closest possible to space conditions and the use of diagnostic methods and instruments for various types of physical research and dimensions. The ground test effectiveness depends on the level of real conditions imitation and the level of attention to all operational factors that influence the credibility of reliability parameter estimation during the development. One of the most important questions in terms of testing effectiveness is the question of testing result accuracy and credibility. The testing process of thrusters mainly goes under the requested conditions of vacuum, created in pressure chambers. To increase the effectiveness of space conditions imitation the paper suggests using the pressure chamber, equipped with the tube shield with the circulating liquid nitrogen under required mass flow rate. The impulse working regime creates instability of propellant moving in pipelines. The paper considers the methods of providing dynamically similar characteristics of supply systems in propulsion systems as well as conformity of hydraulic, inert and wave characteristics of supply pipelines.
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Comparison of methods for initializing starting points on the optimization genetic algorithm
Статья научная
The way to initialize the starting points for optimization algorithms is one of the main parameters. Currently used methods of initializing starting points are based on stochastic algorithms of spreading points. In a genetic algorithm, points are Boolean sets. These lines are formed in different ways. They are formed directly, using random sequences (with uniform distribution law) or formed using random sequences (with uniform distribution law) in the space of real numbers, and then converted to boolean numbers. Six algorithms for constructing multidimensional points for global optimization algorithms of boolean sets based on both stochastic and non-random point spreading algorithms are designed. The first four methods of initialization of Boolean lines used a random distribution law, and the fifth and sixth methods of initialization used a non-random method of forming starting points-LP sequence. A large number of optimization algorithms were restarted. Calculations of high accuracy were used. The research was carried out on the genetic algorithm of global optimization. The work is based on Acly function, Rastrigin function, Shekel function, Griewank function and Rosenbrock function. The research was based on three algorithms of srarting points spreading: LP sequence, UDC sequence, regular random spreading. The best parameters of the genetic algorithm of global optimization were used in the work. As a result, we obtained arrays of mathematical expectations and standard deviations of the solution quality for different functions and optimization algorithms. The purpose of the analysis of ways to initialize the starting points for the genetic optimization algorithm was to find the extremum quickly, accurately, cheaply and reliably simultaneously. Methods of initialization were compared with each other by expectation and standard deviation. The quality of the solution is understood as the average error of finding the extremum. The best way of initialization of starting points for genetic optimization algorithm on these test functions is revealed.
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Compound bending of an orthotropic plate
Статья научная
The problem of longitudinal-transverse deformation and strength of an orthotropic plate on the action of a local transverse force and stretching along the contour of the membrane forces is studied. The direction of laying the fiber of a unidirectional composite that provides the lowest level of stress and deflection is determined. In the zone of application of concentrated force in thin-walled structures, significant bending moments and shear forces occur, which are a source of stress concentration. To reduce stresses, the method of plate tension by membrane forces applied along the contour is chosen. The maximum possible order of membrane tension forces is selected, which provides conditions for the strength and rigidity of the solar panel plate structure, which has a hinge-fixed support along the contour. Pre-tensioning the plate web allows to reduce the stress by 50 times. The problem of compound bending of isotropic and anisotropic plates when applying transverse and selection of longitudinal loads, with restrictions on strength and stiffness, can be called a problem of rational design of the structure. The resulting equations and calculation program can be used in the design of plate structures, as well as in the educational process.
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Constraint handling genetic algorithm for feature engineering in solving classification problems
Статья научная
Feature engineering in machine learning is a promising but still insufficiently studied direction. Creating new feature space from an original set allows to increase accuracy of the machine learning algorithm chosen to solve complex data mining problems. Some existing selection methods are capable of simultaneously increasing accuracy and reducing feature space. The reduction is an urgent task for big data problems. The paper considers a new machine learning approach for solving classification problems based on feature engineering methods. The design of informative features is carried out using extraction and selection methods. Based on the initial data, new sets of characteristics have been created, which include the original characteristics and characteristics obtained by the method of principal components. The choice of an effective subset of informative features is implemented using a genetic algorithm. In order to avoid overfitting and the creation of trivial classifiers, restrictions are imposed on the fitness function of the genetic algorithm, requiring a certain number of features of the original sample, as well as a certain number of features obtained by the principal component method. A comparative analysis of efficiency of the following classification algorithms is carried out: k-nearest neighbors, support vector machine, and a random forest. Efficiency research experiments are carried out by solving applied binary classification problems from the UCI Machine Learning repository of machine learning problems. The macro F1-score was chosen as an efficiency criterion. The results of numerical experiments show that the proposed approach outperforms the solutions obtained using the original data set and the performance of random feature selection (the low bound for the results). Moreover, the accuracy enhancement is obtained for all types of problems (data sets that have more features than values). All results are proved to be statistically significant.
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Contact algorithm measurement method for current crystals area grown by Czokhralski method
Статья научная
For crystals grown from the liquid melt according to the Czochralski method when monitoring and controlling the current crystal area based on the contact measurement method, the requirements for improving the accuracy of measuring the crystal area on the cylindrical part of the growth are determined. To eliminate errors due to the accuracy of stabilization of the melt level in the crucible, an algorithm for the operation of the crystal growing unit is proposed which is performed by the programm using the control system. The evaluation time of the control signal on the growing crystal cylindrical part is taken as the sampling time of a given number of crucible movement pulses. The calculation of the control signal starts at the time of the melt level sensor closure, the calculation of the control signal ends at the time of the melt level sensor closure as well, provided that a given number of crucible movement pulses is sampled. The control signal evaluation time in the previous control cycle is used in the current cycle to calculate the melt level sensor closing and opening pause. In the control system at the moment of the contact sensor closure a pause of the closed and the same subsequent pause of the open state of the level sensor is held. During pauses, the status of the contact sensor is not analyzed by the control system and the control of the crucible ascent occurs at a slowed down and accelerated rate of the crucible ascent during “conditionally” closed and “conditionally” open states of the level sensor. The control system is permanently reset at the end of each control cycle. The program control system provides the above algorithm for controlling the process of growing crystals from the liquid melt according to the Czohralski method, at the same time the accuracy of determining the current area of the grown crystal is about 1 %.
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Control and regulation equipment of electric power system for a prospective piloted transport system
Статья научная
The aim of this work is to consider solving complex of tasks focused on fulfilling the complicated tactical and technical requirements for regulation and monitoring equipment (RME) of electric power supply system (EPS) for a prospective spacecraft. These requirements are imposed due to the need to ensure high reliability of the equipment during operation under the influence of external factors (vacuum, vibro-impact loads, radiation, absence of convective cooling), as well as to achieve high mass-dimensional parameters of the equipment and its high functionality The complexity of problem solving lies in the need to ensure conflicting requirements – high levels of energy density, weight and size characteristics, reliability and durability. These problems fully apply to the RME of the EPS for a prospective piloted transport system (PPTS) which design example shows ways of solving abovementioned problems. The most rational way of solving these contradictions is to increase the specific energy indicators of the main components of the RME devices – power converters, which can be achieved by using modern power electronic elements, using new materials and semi-finished products, for example, printed circuit boards with a metal heat sink, as well as increasing the layout density design. Determining solution is to select an optimal structure of the power converter, which provides the best efficiency. An additional way to reduce the mass-dimensional indicators of the RME is the use of a digital control method, the collection of telemetric information, and the receiving and processing of commands. At the same time, on the contrary, to ensure the specified reliability of the equipment, it is necessary to use excess reservation at the element level – for power components, and the principles of majority reservation at the functional block level – for control and telemetry schemes. Using the example of RME, developed by CJSC “Orbita”, the main EPS parameters of a new generation spacecraft are shown and most important power supply subsystems are considered in the article: the solar energy control subsystem and the power storage subsystem, ways to build them for meeting specified requirements, taking into account the proposed solutions. As a result of this work, the optimal structures of power converters – the current regulator of the solar battery and the current regulator of the battery – were selected, the basic principles of power components reservation ensuring the operability of the equipment in case of a single failure of any component without loss of performance and deterioration of RME parameters as a whole are shown. Block-modular construction method is used for optimal layout and high reliability of the RME, it ensures uniform heat removal from electronic components, which is especially important in vacuum conditions, minimum dimensions and mass optimization of the RME, as well as high mechanical strength of the structure. The implemented principles of building the RME for PPTS using this approach will allow to increase the active lifetime (ALT) and reliability of the spacecraft with a simultaneous decrease in mass and dimension parameters.
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Статья научная
In this paper, we consider the concept of using methods for calculating and designing rocket engine power plants for conversion modeling of local energy in the Arctic and northern regions of the Kras-noyarsk Territory, with an obvious generalization to neighboring administrative formations with similar climatic and structural and logistical conditions. The proposed structure contains power generation units linked to both industrial woodworking waste and natural and industrial thermal tails, identified as sources of low-potential heat, as well as modern low-power reactor plants of block maintenance-free design. The unifying element of power plants is a turbo generator, designed with the use of unconventional, often waste and natural low-grade heat.
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Design of a multifunctional electric propulsion subsystem of the spacecraft
Статья научная
A common way to form an electric propulsion subsystem of the spacecraft is to create specialized equipment or to select the most suitable one from the ready-made ones. However, there are cases when the use of existing equipment is not optimal enough and leads to an unjustified increase of the subsystem mass. Therefore, the ques-tion of creating a minimum equipment set possibility from which it would be possible to form propulsion subsys-tems in optimal way is of interest. The set of tasks, variants of use and possible schemes of placing orbital cor-recting propulsion on the spacecraft are presented. The list of necessary propulsion subsystem elements is pre-sented as follows: a thruster block, a tank, a xenon feed unit, a power processing unit consisting of a power unit and switching units, the complete set of cables and pipelines, the software and mechanical devices for control of the thrust vector (as an option). The necessary capacity of propellant tanks for the tasks of correction and rais-ing of the satellite to GEO with a high-pulse Hall thruster is defined: for orbit correction tasks – up to100 kg, for orbit correction and raising to GEO tasks – up to200 kg. Necessary angle rates of mechanical devices for con-trol of the thrust vector are defined taking into account possible schemes of placing thrusters on the spacecraft. It is shown that in cases when it is required to apply two or more thrusters to increase overall thrust, it is more preferable in the weight aspect to apply a combination of power and switching units instead of monoblock type of power processing units, and advantage can reach tens of kilograms. Provided the listed set of functional units is created, the offered concept will make it easy to form propulsion subsystems of the spacecraft for solving a wide range of tasks. It will reduce the time and money spent on creation of propulsion subsystem for new space-crafts.
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Determination of the digital controller’s characteristics of the switched-mode power converters
Статья научная
The development of spacecrafts equipment is on the way to digitalization. In particular, energy spacecraft conversion devices are being modernized by introducing digital automatic control systems instead of analog ones. This leads to an increase in the efficiency of the power supply system, but at the same time, there is a need to create methods to determine characteristics that will confirm with a high degree of accuracy and conformity of the manufactured sample with the technical requirements specified during its design. The article describes the features of functioning and methodology for determining digital control channel of a pulse voltage converter’s characteristics. The proposed approach is a toolkit for verifying the correct implementation of both the hardware parts of the control channel and the controller, which is a program code implemented on digital control devices. The technique is based on determining the degree of responses correspondence to typical external influences of a hardware-implemented control channel and its model. Based on the transfer functions of the IIR and FIR digital filters, using standard built-in models, the control channel of the pulse voltage converter corresponding to the tested hardware-implemented device is simulated in the package Matlab Simulink. The basic principles of building the software architecture experiment are described. A block diagram of the test complex has been developed, including sources of external influence, control channel, and a test management tool (in this case, a personal computer). An example of applying such a technique to verify the parameters of the developed PID controller is given. Operability and accuracy of the proposed method to determine characteristics of the control channel by reaction to a sequence of rectangular pulses, and by constructing the AFCL are experimentally shown. Application of this verification method to production conditions will allow a complete check of individual central control units (CCU) of energy-converting equipment with closed feedbacks even at the stage of devices development, which will eliminate errors in the implementation of regulators in control loops.
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Статья научная
The main function of a thermal control system (TCS) is to maintain the temperature at nodal points of a spacecraft in given ranges due to redistribution of thermal energy and the discharge of excess thermal energy into space. TCS may have a different design and principle of operation. One of the most common options is TCS using a liquid circuit (LC) and pumping coolant circulation. In the development of promising design-layout schemes for instrument compartments of nonhermetic formation spacecraft, it becomes necessary to state and solve new problems associated with the creation of computational and mathematical models of intermediate convective heat transfer in a fluid circuit. For systems of integral equations of a LC thermal model with fairly complex topographic boundaries and connections, the justification and use of the defining (equivalent) thermal resistance seems to be a compromise of counting implementation of a system that simulates a TCS with integration along the length of the LC. In this paper, for the computational model of the liquid circuit of the thermal control system, including the system of equations of two-dimensional thermal balance of the characteristic surfaces of a nonhermetic formation spacecraft, a method of calculating the determining thermal resistances was proposed and implemented. This method includes the calculation of the complex heat transfer coefficient and the local heat transfer coefficient to the heat carrier flow. The approach considered in this paper allows us to obtain a numerical solution for the distribution of heat flows and temperatures of liquid circuits with complex topographic boundaries and connections with minimal loss of accuracy. The determination of the local heat transfer coefficient makes it possible to take into account the influence of changes in the temperature of the coolant flow on the overall picture of convective heat exchange.
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Developing the laboratory test bench of fuel three-point measurement
Статья научная
The development of digital technology allows continuous improvements in many areas. This paper reflects the development of a new fuel measurement method. To measure the fuel, the authors propose three fuel sensors and a computational element to simulate the position of the fuel level in space with further calculating the volume of fuel, to reduce errors due to the fuel meters operation. The main advantage of this system is the elimination of errors arising from the evolution of an aircraft, as well as its uneven movement. The paper demonstrates a phased development of a laboratory test bench to study the three-point method to measure fuel. In the course of the work, a vessel is assembled to simulate the fuel tank of the aircraft. The vessel is a glass container with submersible measuring sensors. Also, the research contains calculation of the bridge electrical circuit to compute a voltage value at each sensor. In the test, transformer fluid substitutes fuel, since it acted as a dielectric. The program code for the microcontroller is recorded. The proposed method has several advantages in comparison with traditional methods of measuring the fuel level; a mathematical model is presented, on the basis of which the level of fuel in the aircraft fuel tank is measured.
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Development of SEM method for analysis of organ-containing objects using inverse opals
Статья научная
The purpose of this study is to test the possibility of using inorganic macroporous structures of inverse opal in sample preparation for scanning electron microscopy of biological objects. As an absorbent substrate we used silica inverse opals prepared by a sol-gel method to study the biological objects. The process of manufacturing the inverse opal involves a complex multi-stage technological process. First, we synthesized submicron spherical particles from polymethylmethacrylate by the method of emulsifier-free emulsion polymerization of methylmethacrylate in an aqueous medium in the presence of a diazoinitiator. This method can be used to obtain an ensemble of particles with high monodispersity, the average size of which can vary in the range from 100 to 500 nm. Then, by self-assembly technique, we deposited the beads of polymethylmethacrylate into ordered matrices (templates), mainly with a face-centered cubic lattice. The resulting mesoporous structures, called artificial opals or colloidal crystals, had lateral dimensions of about 10 × 10 × 2 mm. Then we heat-treated the opals to 120 °C to harden the template before being impregnated with the precursor. Further, we impregnated the opals with silica sol with a particle size distribution from 1 to 5 nm, obtained by hydrolysis of tetraethoxysilane in the presence of hydrochloric acid, and then, after curing and drying the impregnating composition in air at room temperature, we multi-stage fired them up to 550 °C at normal pressure in the air atmosphere to remove all organic components. As a result, the macroporous metamaterial (the so-called inverse opals) with an open system of pores up to 400 nm in size, occupying about 80 % of the volume, were obtained. We studied lactic acid bacteria of cucumber brine and human red blood cells with TM4000 Plus, SU3500 and S-5500 scanning electron microscopes. Auxiliary substance for the sample preparation was ionic liquid VetexQ EM (Interlab LLC). We showed that it is possible to use the inverse opal as an absorbent substrate for sample preparation and rapid analysis in scanning electron microscopy without pre-drying, chemical treatment, or temperature exposure. To improve imaging in the electron microscope, we used sputter coater to cover the inverse opal surface with a thin film of platinum. The use of ionic liquid in combination with the absorbent porous medium allows preserving an original shape of the biological structures. Using the human red blood cells and lactic acid bacteria, we showed that it is possible to carry out of the morphological analysis of the cells using various scanning electron microscopes. We found that on the basis of the inverse opal, there is a fundamental possibility of creating the absorbent substrate suitable for repeated use in the study of the biological objects. At the same time, trace remnants of previous samples remaining after annealing the plate do not introduce significant distortions when conducting new series of observations. In this study, we obtained high-quality electronic micrographs of the biological objects with high resolution and contrast. At the same time, due to the use of the inverse opals as the absorbent substrate, time and financial costs for research are reduced.
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Статья научная
The article examines the role of information technology at industrial enterprises of the rocket and space industry, provides the results of the analysis of scientific sources to organize information support systems for making management decisions, an analysis of existing methods for constructing management account-ing at enterprises and methods of its automation. Conclusions are made about the insufficient elaboration of the studied solutions, both from the point of view of the logic of the organization of accounting, and from a technical point of view. The main tasks of the information support system, methods of forming effective management accounting and the goals of its implementation are determined. An approach to create an in-formation support system in the form of a built-in control database in the form of an OLAP solution is pro-posed, through which functional information systems are integrated, and detailed management accounting related to accounting and tax accounting is built into a single system in a single information space. The article describes the advantages of implementing the proposed system, which allows for a comprehensive retrospective and operational analysis of the current state of the processes oc-curring at the enterprise with a monetary value using SQL tools with a high degree of confidence in the data. The principles of creating elements of the information system for the subsequent effective plan-fact analysis and development of management decisions are discussed. A diagram of the organization of a sin-gle information space and a system that provides information support for enterprise management processes is given, the main information flows are considered. The logic of maintaining the process of forming a structured data warehouse is described, while automating the financial and economic part of the auto-mated control system based on the presented method of organizing data, which allows to link management, accounting and tax accounting with one source of relevant data, while creating an effective OLAP solution. An illustrative example of the organization of data in the form of linking the reflections of primary documents by means of a database using the proposed method, which provides the possibility of operational analysis of receivables and payables and the implementation of preliminary financial control-ling, is given. The research provides examples of user interfaces from the developed information support system based on the described methods of data organization. Conclusions are made about the effectiveness of the proposed solution.
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Статья научная
Aluminum-based alloys are widely used in many branches of modern industry (aviation, mechanical engineering, shipbuilding, instrument-making, energy and medicine, etc.). The promising method for further expanding the scope of these alloys is surface treatment based on the use of concentrated energy fluxes (laser beams, plasma flows, powerful ion beams, continuous and pulsed electron beams). The purpose of this paper is to establish the possibilities of integrated electron-ion-plasma modification of the structure and properties of the surface layer of technically pure aluminum A7. The surface alloy was formed in a single vacuum cycle using the “KOMPLEX” facility (ISE SB RAS) by spraying a titanium film with a thickness of 0.5 μm and the subsequent irradiation with an intense pulsed electron beam in the aluminum melting mode. After 20 “spraying/irradiation” cycles, nitriding (540 °C, 8 h) of the formed surface alloy was performed in a low-pressure gas discharge plasma using the plasma generator “PINK”. Surface alloy studies were carried out applying the modern materials science methods (scanning and transmission electron diffraction microscopy, X-ray phase analysis, determination of hardness and wear resistance). The choice of elements alloying the surface layer of aluminum was based on the analysis of binary state diagrams of Al-N, Al-Ti, Ti-N systems and the isotermal section of the ternary system Al-Ti-N. It has been shown that formation of an entire series of binary and ternary compounds, including MAX-phases of the composition Ti2AlN and Ti4AlN3, is observed under equilibrium conditions in the Al-Ti-N system. The carried out research has allowed to state that an integrated method of electron-ion-plasma modification of technically pure A7 aluminum by nitriding (540 °C, 8 h) of the surface alloy formed by pulsed melting in vacuum of the Al-Ti system (20 “spraying/irradiation” cycles with an electron beam with parameters 10 J/cm2; 50 μs; 10 pulses; the titanium film thickness in each cycle 0.5 μm) leads to formation of a multiphase multielement submicro-nanocrystalline surface layer up to 20 μm thick. It is shown that the mechanical (microhardness) and tribological (wear resistance and friction coefficient) properties of the formed surface layer exceed manifold the properties of the original commercially pure aluminum A7.
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Development of interface module emulator architecture for spacecraft life support systems
Статья научная
The article gives an analysis of special characteristics of ground-based experimental evaluation of on-board radioelectronic equipment, taking the control unit of up-to date spacecraft on-board control complex as the test objective. The focus is the problem of providing testing procedures of the specific software employed in design and manufacture process. A solution of the problem is worked out on the basis of performance of a hardware-software complex which emulates interface modules for the computing module of control unit. According to the general operation algorithm of the control unit, the developed complex is regarded as a multi-user system. The main functional requirements for hardware-software emulator, regarded as the corresponding queuing system, are also defined. The results of the experiments with the computer module operation prompted the requirements for the emulator response time from the point of view of its operation stability in real strict-time mode. In order to ensure the required efficiency of operation, the emulated functions of the interface modules are classified according to the severity level of their execution determinacy. The results of experimental evaluation оf the service channel hardware design variants when applying multi-functional reconfigurable input-output digital devices allowed to develop a hardware-software emulator structural circuit based on operation parallelism of programmable integrated logic circuits and flexibility of software reconfiguration. The realization of emulated functions of selected classes within the available architecture was carried out using the corresponding hardware blocks and software module. The presented analysis of the emulator response limits was performed with the application of National Instruments technologies. The results of the developed hardwaresoftware emulator evaluation and practical application, as well as other possible ways of applying the proposed approach for tests of spacecraft on-board radio-electronic equipment and space system components were also analyzed.
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Статья научная
The original method for encoding binary data streams based on QPSK quadrature phase shift keying in a wireless optical communication channel in the visible range is suggested. The algorithm for analyzing signals in the receiving tract is presented. It allows to analyze the presence of two or three pulses of different colors at the input, which will signal the presence of interference or the occurrence of "illumination". In addition, the algorithm provides a possibility of dynamic compensation of external "illumination" by changing the gain of the photodetectors and adjusting the brightness of emitting LEDs. The functional scheme of the device for realization of the offered coding method in the wireless channel on the basis of optical radiation has been developed. Given that most photodiodes are sufficiently wide-band in the visible range of light waves, to increase sensitivity of each color channel and selectivity of the receiving tract it is necessary to apply optical filters for each color channel. The most effective are interference filters made of optically transparent materials with different physical characteristics. The approach for calculating optical filters has been presented.
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Development of the concept of a reusable liquid rocket engine with three-component fuel
Статья научная
The article considers a promising direction for the development of liquid-propellant rocket engines (LPRE) – the use of three-component propulsion systems. The interest in this topic is based on a number of advantages that can be obtained by using this LPRE concept, namely: saving the mass of the launch vehicle (LV) by using a denser hydrocarbon fuel at the initial launch site; high specific impulse values at high-altitude launch sites due to the use of a more efficient pair of fuel components (FC): liquid oxygen + liquid hydrogen; reducing the cost of removing the payload, due to the use of a single propulsion system for both launch sites. An analytical review of implemented three-component LPRE schemes developed in Russia and abroad has been conducted, and their main advantages and disadvantages have been highlighted. Based on a detailed study of a number of circuit solutions for liquid-propellant rocket engines running on three-component fuel, the concept of a two-mode single-chamber three-component engine made according to a closed circuit with afterburning of generator gas is proposed. The oxidizer is liquid oxygen, the fuel is RG-1 kerosene and liquid hydrogen. In the first mode, the engine runs on three components, the share of liquid hydrogen in the fuel mixture is 4% of the total consumption of components. In the second mode, the engine runs on FC liquid oxygen + liquid hydrogen. The results of a computational and analytical study of the optimal design parameters of the engine are presented. The aim of the study was to understand the qualitative picture of the influence of various fuel parameters on the thermodynamic properties of the combustion products of the fuel mixture and the engine efficiency. Based on the results of the study, the optimal percentage of fuel components was determined. A mathematical model for calculating a three-component LPRE has been developed. The results of calculation of energy coupling are presented. A comparative analysis of the mass characteristics of the designed propulsion system is carried out.
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Development of the heat panel of the small space apparatus for navigation support
Статья научная
To clarify the trajectory of the spacecraft in a given orbit, the parameter of unmodeled acceleration is taken into account. Today, in the design and manufacture of a spacecraft to meet the requirements of the technical specifications for the maximum allowable values of unmodeled accelerations during the operation of on-board equipment, it is necessary to take into account the effects of asymmetric heat fluxes from the panels of the spacecraft on the deviation of its center of mass from a given orbit. This article discusses the problem of the influence of asymmetric heat fluxes from the surfaces of the spacecraft emanating from the panels ± Z, + Y (deterministic and non-deterministic component) on the level of unmodeled accelerations, which significantly affects the trajectory of the spacecraft. In order to meet the requirements for the temperature control system in terms of ensuring efficient heat removal from the on-board equipment devices and its distribution over the surface of the instrument installation panel, it is necessary to significantly improve the technical characteristics of heat transfer and heat conduction processes in the spacecraft. The analysis of the current thermal control system in modern satellites is carried out and its shortcomings are revealed. A constructive option is proposed for creating an energy-intensive thermal panel, which allows more efficient heat removal from devices and distribution over the panel. The designed thermal panel is a flat sealed panel of a single complex design of aluminum alloy, made by the additive technology method. The dimensions of the thermal panel are limited by the structural dimensions of the working area of 3D printers. At the moment, the main dimensions reach 600-800 mm. An increase in the working area in the future will enable the installation of large-sized electronic equipment. A two-dimensional mathematical model for calculating heat transfer processes in the designed thermal panel is presented. For the calculation, specific average values are introduced that characterize the effective cross sections for the vapor channels and the wick in the longitudinal and transverse directions, physical parameters (porosity of the wick and its degree of liquid saturation).
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Статья научная
The article provides a brief description of the flight scheme of a prospective automatic spacecraft intended for the study of Mars and its satellites by remote and contact methods. At the near-Martian expedition site, it is planned to first bring the vehicle into orbit of the artificial satellite Deimos, and then landing on Phobos with the subsequent delivery of its soil to Earth. The main ballistic characteristics of the spacecraft flight conditions at all stages of the flight at launch after 2025 are given. The time frames for the five starting periods are considered - in 2026, 2028, 2030, 2033 and 2035. The launch of the spacecraft on the flight path to Mars is performed by a heavy class launcher. The article describes the design of the vehicle, propulsion systems of its modules and flight scheme at all stages – from launch from the Earth to landing on Phobos, and returning back to Earth. The article describes the propulsion systems of the main spacecraft units proposed for the mission implementation – the propulsion module, the flight landing platform and the return vehicle. The designs of these units are provided in the work. Flight schemes have been developed in accordance with their characteristics, which allows conducting remote study of Deimos, making a soft landing on the surface of Phobos, and then delivering samples of its soil to Earth. The project should be developed on the basis of the spacecraft launch from the Vostochny launch site by the Angara- A5 launch vehicle and the KVTK upper stage. An alternative variant of the construction of a spacecraft involves the use of a vehicle of a lighter class - perspective Soyuz-5 launch vehicle and Fregat-SBU upper stage. In this case, the engine module is excluded, and the flight and landing module is replaced by a heavier version with larger tanks. Both proposed options for constructing a spacecraft make it possible to implement the developed trajectory, while ensuring full-time operation of the target equipment and conducting a set of experiments during a given period of active spacecraft existence.
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