Статьи журнала - Siberian Aerospace Journal
Все статьи: 330
Design of the fastening assembly of the guys on the power spokes reflector
Статья научная
Currently, global communication systems are developing towards mastering high frequency bands for organizing high-speed information transmission channels, which requires large-sized antenna systems with reflectors up to 50 meters. Most of the technical solutions used for assembling large-sized reflectors are based on technological volumetric templates that geometrically completely imitate the necessary reflective surface of the reflector. The mass of such templates increases in cubic dependence on the increase in the diameter of the reflector, which is why it becomes more and more laborious to use them when assembling large-sized antennas due to the increase in the dimensions and weight of the templates. The purpose of the study is to design the attachment point for guy wires on the power spoke of the re-flector for a "templateless" assembly. The spoke is a composite isogrid structure on which arms are fixed for attaching power units. The fastening unit is an assembly unit consisting of a bracket and clips and al-lows you to precisely adjust the necessary pull tension force to fix the cord in the working position without the use of one-piece fastening methods. The analytical approach and finite element analysis were adopted as research methods. Using an ana-lytical calculation, the maximum tensile force of the guys in the designed unit was determined, thereby set-ting the maximum load for its operation. The coefficient of friction between the cord and the clamp in each individual case is determined experimentally. After simplifying the design and construction scheme of the bracket, the analytical calculation was carried out for a three-dimensional rod frame. To confirm the results of the calculation, a finite element model of the bracket was built and its static analysis was carried out. For the developed model of the bracket, the maximum stresses were determined and their comparative analysis was carried out with the results obtained analytically. With the help of solid modeling, the mass and overall characteristics of the braces fastening unit are determined. The limiting ranges of tension forces and the materials used in the knot, as well as its strength characteristics, were determined. This unit can be used in the "templateless" method of assembling a reflector for a wide range of large antennas, it has high manufacturability and versatility.
Бесплатно
Detection of information system objects interaction with DGA domains
Статья научная
Currently, malware developers are actively using domain name generation technique called DGA to es-tablish communication between malware and its command centers. Domain name generation in accord-ance with the given algorithm allows malicious software to bypass information protection tools blacklists, thus making blacklists ineffective, and establish a communication channel to receive control commands and parameters, as well as to transfer information from the information system to external resources con-trolled by attackers. Thus, it is necessary to develop new approaches to DGA generated domain names de-tection using DNS traffic of an information system. During the research, the authors have developed a solution for detecting information objects interaction with DGA domains based on the use of machine learning. The detection of this interaction occurs in two stages. On the first stage the classification task is being solved for each DNS name from overall infor-mation system DNS stream. On the second stage, for each DNS name classified as DGA, corresponding DNS query is being enriched using data from external sources and a final decision about the malicious nature of the query to resolve this DNS name is being made, followed by a notification of a security admin-istrator via e-mail channels. The paper describes the process of developing a classifier based on machine learning, defines the input data of the DNS name necessary for classification, presents the results of classifier training on a repre-sentative set of test data. The logic of making a decision about the malicious nature of DNS queries has been substantiated. The developed solution was tested using an experimental stand. Some recommenda-tions for correct classifier operation support are proposed. The application of the developed solution will make possible posteriori detection of information interac-tion of malicious software working on compromised information objects with the servers of attackers com-mand and control centers.
Бесплатно
Determination of coupling loss factors for beams connected at an angle
Статья научная
The use of a statistical energy method for the analysis of dynamic systems assumes that coupling loss factors of subsystems must be known. Coupling loss factors show what part of energy moves from one subsystem to another. They are included in the system of energy balance equations and must first be determined analytically, experimentally or numerically. The most promising of the listed methods is a numerical one. In particular, this paper uses a finite element method. The purpose of this study is to determine the coupling loss factors of two subsystems in two versions of their relative positions. The basis is the model of an L-shaped connection of two beams, which is quite common in such studies. L-shaped connections of structural parts are often found in building structures, but in other industries, such as the development of space and aviation technology, structural elements are often connected at an angle other than 90°. Since energy methods (EMs) can also be applied to aerospace industry, when developing approaches to analyzing structures using such methods, it is useful to know how the energy parameters of a system, in particular coupling loss factors, change depending on the fact at what angle their components are connected. The paper considers two system configurations: in the first, the beams are connected at a right angle, in the second - at an angle of 45°. The coupling loss factors of the beams are calculated for both system configurations. Conclusions are drawn about the possibility of disseminating the results obtained to more complex structures, namely spacecraft structures.
Бесплатно
Статья научная
The article describes the results of tests that have been carried out at the manufacturing plant of refrig-eration devices. These results have made it possible to estimate the capability of using a new method of testing refrigeration devices for compliance with the standards established by GOST, which determine the specific heat and power properties of each refrigeration device, depending on its type (single-chamber or with two-chambers, with one compressor or with two, etc.), passing acceptance tests. The graphs of the active power of the device will be presented when it is connected to the power supply network and the de-pendence of the change in the power graph depending on time will be described, the signs of the graphs of faulty refrigeration devices will be described, indicating the cause of the malfunction. The authors indicate the parameters by which it is proposed to compare the obtained power graphs with the reference graphs obtained when testing reliably serviceable refrigeration devices. Based on the results of comparing certain values of the parameters characterizing the device it is proposed to judge the compliance of each individu-al refrigeration device with the standard. It also provides a description of the algorithm that will be used to determine the compliance of the refrigeration device with the established parameters of heat and power characteristics that determine its performance. The implementation of this algorithm will be carried out by writing an appropriate program for the programmable logic controller (PLC).
Бесплатно
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.
Бесплатно
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.
Бесплатно
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.
Бесплатно
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.
Бесплатно
Development of a human-machine interface for cascade control mills in obtaining nepheline ore charge
Статья научная
Aluminum and alloys based on it are the main materials for space engineering, both in the production of vehicle parts, and in the organization of power supply and electronics. The raw material for producing aluminum is alumina. Alumina production is a multi-stage process that includes the processing of raw materials in various ways: mechanically, thermally, chemically. Mechanical processing of raw materials is the first stage of production, it includes a crushing department and a batch preparation department. The preparation of the charge from nepheline ore for further stages of production takes place in mills with the addition of limestone and recycled solution. The ratio of the components entering the mills directly affects the composition of the charge and the quality of the final product. At the same time, the required quality of the charge is not always ensured, since the costs of the components are set by a person based on the re-sults of a rare chemical analysis performed by the laboratory with a delay. The aim of the work is to improve the control of the mill when receiving a mixture of nepheline ore. A virtual mill control program and a mnemonic diagram were developed in the TIA Portal software environ-ment using the S7-1500 microprocessor controller. A system for automatic control of the lime and alkaline modules of the raw charge has been developed. The control program is built on the basis of calculating the moisture content of the charge, as well as the al-kaline and limestone modules, depending on the composition of the ore, limestone, as well as the feed rates of circulating water, ore and limestone to the mill. The mnemonic diagram includes an indication of important process parameters, trends in input and output characteristics, and tools for setting control actions.
Бесплатно
Статья научная
The paper presents the developed methodology and designed a device for determining the Mach number during supersonic gas outflow. An analysis of various methods for determining the Mach number was carried out, including measuring the pressure at the flow boundary, the use of shock waves, and the use of optical methods. A comparison of the accuracy of the readings when using the considered methods was made. Based on the results obtained, a technique for high-precision determination of the Mach number has been developed, including a combination of several independent measurement methods. A device has been designed that implements this measurement technique, and the results of experimental tests in a wind tunnel have been reviewed, including instrument readings, graphs and tables confirming the accuracy and reliability of the data obtained. Their accuracy and reliability are analyzed. Using the analysis, it is possible to ensure the selection of the most rational method for determining the Mach number at the initial stage of designing aircraft, such as airplanes, missiles, fighters, and UAVs. Accurate knowledge of the Mach number allows engineers to optimize the aerodynamic characteristics of the aircraft, ensure flight safety, improve engine efficiency and overall air transport performance. In addition, the Mach number is the most important criterion of similarity when modeling in aerodynamic research, which makes the developed methodology and device relevant not only for the design of aircraft, but also for a wide range of scientific and engineering research in the field of aeronautical technology. It is emphasized that the presence of a reliable method for determining the Mach number can significantly reduce the time and resources spent on testing and improving aircraft, and also contributes to the development of innovative technologies in the field of aviation and astronautics.
Бесплатно
Development of a methodology for testing SpaceWire network switches
Статья научная
The paper presents the main points of the developed methodology for testing SpaceWire network switches. The main objectives of testing this equipment are outlined. A block diagram of the workplace is provided, as well as a list of equipment with its brief description for conducting tests. To conduct the tests, special software was developed, implemented in the form of a console user application. The methodology describes in detail each step of working with this application. This article describes the algorithms that are implemented when working with the application. These algorithms are presented in the form of flowcharts, as well as in the form of a text description. Two groups are distinguished among the algorithms: basic and advanced tests. For the first group, we can distinguish: a basic test - to check the principle of removing the header in accordance with the path addressing; a load test - to check the correct operation of the switch at high load of the switching matrix, as well as checking the deletion of incoming packets that do not contain addresses in their header to be sent to one of the switch ports; an exceptional situation test is used to check the correct operation of the switch when the receiving buffer is loaded with incoming data. For the second group, we can distinguish: the routing table test - to check the correctness of the processing by the switch of the rows recorded in the routing table; the broadcast test – to check the ability of the switch to send one data packet from several ports at the same time; the adaptive group routing test – to check the ability of the switch when selecting multiple ports for data transmission to send them from the port having the highest priority. All the indicated algorithms were tested on a radiation-resistant fault-tolerant ultra-large inte-grated circuit of a programmable master switch of the 3rd level. In conclusion, further plans for the devel-opment of the methodology are outlined.
Бесплатно
Статья научная
Today, we can distinguish a number of promising reusable launch vehicles “SV Wing” – a reusable cruise stage of a light-class launch vehicle; “Baikal-Angara” reusable booster of the first stage of the An-gara launch vehicle; “Soyuz-7” is a reusable two-stage medium-class launch vehicle; flight design tests of “Soyuz-7” are planned for 2025. To maintain the operational characteristics of aircraft, it is necessary to develop a maintenance system that ensures the specified reliability of flying vehicle assemblies. The pur-pose of this work is to develop a model for detecting malfunctions in the process of maintenance of units and systems of aircraft. Within the framework of this work, an algorithm has been developed, which is based on the method of statistical testing, which allows, at low computer time, to analyze the maintenance process in more detail, taking into account the duration of separate operations and their effectiveness. Da-ta on the duration and efficiency of separate operations can be obtained in the process of special tests of equipment by timing and analysis of service results. For modeling it is necessary to have the following ini-tial data: the law of distribution of the duration of separate operations; the effectiveness of troubleshooting during separate operations. The algorithm implements two types of maintenance: full and reduced. Re-duced maintenance provides for operations that are most effective in terms of the number of faults to be eliminated: adjustments, regulations, search for faulty elements. The developed model makes it possible to investigate the possibility of reducing the downtime for maintenance without a significant decrease in the quality of maintenance, namely: to assess the effectiveness of maintenance when it is carried out according to the full and reduced scheme; evaluate the effectiveness of maintenance when performing maintenance in a limited time; justify the most appropriate ways to improve the quality of service, provided that the down-time for maintenance is limited and predict the likelihood of detecting malfunctions during the maintenance process. The practical significance of the results of this work can be achieved in the aerospace industry, in particular, at the design stage (testing and operation) of a maintenance system for reusable elements of launch vehicles.
Бесплатно
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.
Бесплатно
Статья научная
This article presents a detailed description of an experimental setup for testing two-phase thermal control systems of spacecraft. The setup is a climatic chamber for simulating real operating conditions of elements in the subzero temperature range and includes three circuits: a coolant pumping circuit corresponding in parameters to the thermal control system under study, a cooling system circuit, and a thermal load simulator circuit. Electric heating elements are used as a thermal load simulator. Transparent inserts provide the ability to visually monitor the structure of a two-phase flow during boiling and estimate the volume content of the vapor phase. A testing methodology was developed for the installation under consideration, including a testing algorithm and a description of the software and hardware testing tools. The software and hardware testing tools include electronic measuring tools for the main parameters of the operating modes of the two-phase thermal control system and an automated testing process control system. The developed automated testing process control system provides the ability to monitor a wide range of thermal and physical parameters of the coolant at various points in the circuit. The control system is based on the use of programmable logic controllers. To automate the operation of the installation, the OWEN PLC200 controller is used in the stand – a monoblock controller with discrete and analog inputs/outputs, designed to control and manage the operating modes of small systems. The software part of the algorithm is based on the CODESYS environment. The results obtained in the work can be used in planning and implementing programs for ground-based experimental testing of two-phase thermal control systems, in developing test stands for conducting research on spacecraft systems.
Бесплатно
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.
Бесплатно
Статья научная
Exploring the Solar system by humans implies the development of long-term habitable bases on several planets: the Moon, Mars, and others. Maintaining an environment favorable for a crew on such bases is possible due to life support systems (LSS), where a closed mass transfer of products and waste is imple-mented among the crew, the higher plants and other links. Closure increases the reliability and autonomy of the system, and reduces the cost of its supply.Controlling such mass transfer appears to be a difficult technical task requiring many man-hours, which is a valuable resource in the implementation of manned space missions. In the general case, this problem is solved by means of automation, however, it is neces-sary to take into account the features of the processes that support mass transfer, since this will allow find-ing ways to simplify the hardware and logical components, increase their versatility and reliability. This article presents an analysis of the technological processes of the experimental unit for extracting NaCl from solutions of mineralized human metabolites and proposes a simple control algorithm to be used for all processes of the unit without fundamental changes. Without developing a NaCl transformation cycle, it becomes almost impossible to develop a long-term functioning biological and technical life support sys-tem – the optimal LSS option for alien bases. In such systems, mass transfer occurs between the crew and the higher plants and there is a danger of NaCl accumulation in irrigation solutions and subsequent poi-soning of the plant link. Therefore, the problem of controlling the NaCl transformation cycle in mass trans-fer processes of a high degree of closure is relevant, and the universal principles of automated control can be used not only in space, but also in terrestrial applications: in closed agrotechnical cycles and scientific, and educational stands.
Бесплатно
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.
Бесплатно
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.
Бесплатно
Development of the CYCLOPS CubeSat payload
Статья научная
The number of CubeSat satellites launched has been increasing over the past decades. These satellites have a number of advantages: short development time, low cost, possibility of modifications for certain scientific tasks and testing of technical solutions and new developments. This article describes payloads of a small spacecraft: CubeSat 3U CYCLOPS designed by D.F.Ustinov Baltic State Technical University "Voenmeh" within grant under Space-Pi program. The purpose of the study is to create, test and study the performance of payload modules of the vehicle, built using commercially available components, under space flight conditions. The text describes the structure of interaction between the payload and the OrbCraft-Pro 3U platform from Sputnix LLC. The process of development of payload control board is con-sidered. The control system software for mechatronic and multiaxis actuator modules with logging and error correction is described. In addition to the above-mentioned modules, the payload control system was also developed to carry out a series of experiments in the presence of a small spacecraft in orbit. The paper explains how the spacecraft communicates with the ground via special software Houston control applica-tion and Houston Telnet. The results describe tests performed on the mechanical components of the space-craft. Examples of telemetry packets received from on-board the spacecraft are given. The article also re-flects further plans for the project and the prospects of using the developed hardware for implementation in large-scale space systems and complexes. Also as part of the project students were able to gain engineering experience in the development of devices designed to work in space conditions.
Бесплатно
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.
Бесплатно
