Journal articles - Siberian Aerospace Journal
All articles: 400
Plasma spheroidization of metal and ceramic powders
Scientific article
The paper presents the results of plasma spheroidization of metal and ceramic powders. The aim of the study was to conduct a comparative analysis of two methods for feeding powders into a plasma jet – under the nozzle section (plasma torch F-4) and along the axis of the plasma jet (plasma torch PM-1). Metallic (Cu, NiCr) and ceramic (Al2O3, ZrO2) powders were used as objects of research. To implement the spheroidization process, a specialized water-cooled reactor has been developed that provides controlled cooling of molten particles. Numerical modeling of thermal processes in the reactor confirmed the efficiency of the cooling system: the stationary thermal regime is established 286 seconds after the start of operation of the plasma torch, and the increase in the temperature of water in the reactor, measured experimentally, is consistent with the data obtained by calculation and is 5 °C. It has been established that the PM-1 plasma torch provides homogeneous and finely dispersed powders, however, when processing materials with a low melting point (copper), the powder begins to melt in the inlet channel of the plasma torch, settles on the walls of the nozzle and, over time, clogs it. Spheroidization with the supply of powder under the nozzle section makes it possible to process any materials, however, larger particles with a wide granulometric distribution are formed, especially when processing refractory powders. Based on a comprehensive analysis of the microstructure and granulometric composition of spheroidized powders, technological recommendations have been formulated for choosing the type of plasma torch depending on the required powder properties: the PM-1 plasma torch is preferred for obtaining homogeneous fine powders, and the F-4 plasma torch is preferred for processing low-melting materials and ensuring the maximum degree of spheroidization.
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Plasmotron for coating internal surfaces of component parts
Scientific article
Plasma spraying is one of technologically appropriate, productive and effective methods of applying protec-tive coatings to component parts produced by aerospace, metallurgical and other industries, objects exposed to high temperatures, dynamic loads, aggressive media, etc. Plasma spraying makes it possible to apply quite a va-riety of materials, such as metals, oxides, carbides, nitrides, etc. to different surfaces. Certain problems may arise, though, in applying protective coatings to the inner surfaces of cylinders and complex parts of small size (about 100 mm). These complexities depend on the dimensions of the plasma generator proper. There are no home-produced small-size plasma torches, they are all imported from other countries. That causes certain prob-lems with delivery, to say nothing of very high commercial price. One of the ways to improve the situation is to develop small-size plasmatrons capable of applying high-quality coatings to the internal surfaces of limited-size parts; that may significantly reduce expenses through import substitution. The effectiveness of the proposed device is in working out a method of applying high-quality coatings to the inner surfaces of orifices as small as 60 mm in diameter (operating a plasmatron of smaller size), as well as in significant cost reduction due to domestic production. Sample calculations show that the price of that plasma-tron type will not exceed 0.5 million rubles.
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Point defects in nematic liquid crystal materials with conical anchoring at the interface
Scientific article
The topological point defects in nematic liquid crystal materials have been studied. The method of oblique light incidence has been proposed to determine an azimuthal director angle of an achiral nematic as well as a chiral nematic (cholesteric). The idea of the method is based on the dependence of the optical phase difference between ordinary and extraordinary light beams on the azimuthal director angle at the layer center at oblique incidence of light on a structure in which the polar director angle of a nematic liquid crystal is not equal to 0° or 90° (conical boundary conditions). It has been shown that the phase difference reaches a maximum at a zero azimuthal angle at the center of the layer regardless of the total twist angle of the director. The developed method has been used to analyze topological defects formed in the nematic and cholesteric layers under conical boundary conditions at the interface. The director field distributions of nematic and cholesteric near the surface point defects (boojums) with topological charges m = +1 and m = –1 have been drawn based on the experimental data. The proposed method of oblique light incidence can be used to analyze a wide class of the achiral and chiral liquid crystal media of various types: smectics, nematics, and cholesterics with tilted or hybrid boundary conditions.
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Article
During the period of active lifetime in different types of orbits, spacecraft (SC) are exposed to various factors of outer space. The main factor influencing the performance of radio-electronic equipment is the ionizing radiation of outer space. The main effect associated with the impact of ionizing radiation of outer space on the SC (dose effects), in its physics, is determined by the radiation dose absorbed in the components of the electronic component base (ECB) and construction materials during the entire lifetime. This effect explains the failures in the operation of radio-electronic equipment due to the degradation of the parameters of the used ECB products and materials. Calculation of levels of exposure to absorbed doses depending on various parameters of the orbit is a necessary and important task for ensuring the SC functioning during a given lifetime, since calculations of radiation resistance are based on the levels of exposure in orbit. Carrying out calculations taking into account the SC and onboard equipment (OBE) design features is the key problem from the point of view of minimizing mass protection and the scope of tests of critical ECB products. In addition to taking into account the design of the SC and the OBE, an important aspect when calculating the radiation resistance is taking into account the relative position of the OBE in the SC. The paper considers the possibility of unifying the requirements for radiation resistance for SC with dif-ferent operating orbits and lifetime, as well as the possibility of carrying out a unified calculation without taking into account the design features of the SC, OBE and relative position within the SC.
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Scientific article
This paper presents an overview of the current technical problem related to two-phase spacecraft thermal control systems and possible technical applications of thermal energy recovery in the organic Rankine cycle as an integral part of thermal management systems. The design solution involves the integration of a steam microturbine behind an evaporator radiator. The microturbine is a tangential supply device and a radially centripetal impeller of low speed nst<40. In this area, there is no reliable data on the design and energy of both the supply device and the impeller. The energy (loss of enthalpy) of the supply device mainly determines the transport of the swirling flow to the impeller and, as a result, the circumferential operation on the turbine. A prototype of a radial microturbine has been developed and presented in order to evaluate the design of the flow part of both the supply device and the impeller. As a result of the analysis, the main determining hydrodynamic areas necessary for hydrodynamic analysis and mathematical elaboration of the flow calculation algorithm with an assessment of energy losses are identified: the flow of a swirling flow of a radial-annular slit; axial-annular slit and tangential supply device. The first two algorithms assume computational modeling, the model of energy losses in a tangential supply device is not amenable to analytical modeling because it includes a sequence (or compatibility) of flows under boundary conditions defined as “local resistances”: the sudden expansion, reversal of the flow, together with a section of radially circumferential flow, the mutual influence of these boundary conditions assumes only an expe rimental assessment of energy losses in a tangential supply device through the loss coefficient of local resistance in the range of changes in geometric and operating parameters. As a result of experimental studies, a database has been proposed on the loss coefficient of tangential microturbine supply devices in the field of the practical range of the existence of operating and design parameters.
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Prediction of formation of competing phases during the growth of Cr2GaC THIN FILMS ON MgO(111)
Scientific article
MAX-phases are a family of ternary layered compounds with the formal stoichiometry Mn+1AXn (n = 1, 2, 3...), where M is a transition d-metal; A is a p-element (for example, Si, Ge, Al, S, Sn, etc.); X is carbon or nitrogen [1]. Layered triple carbides and nitrides of d-and p-elements (MAX-phases) exhibit a unique combination of properties characteristic of both metals and ceramics, which makes their application as various coatings in space industry very promising. Obtaining the desired properties of the MAX-phases depends on the technological conditions of material synthesis. This requires thorough theoretical modelling of the elements’ interaction at the interface. Concurrent growth of competing phases along with the MAX-phase may occur due to the favorability of competing phases’ formation and may also be promoted by lower energy interfaces with the substrate in comparison with a MAX-phase. In this work, we study thermodynamic favorability of competing phases and Cr2GaC MAX-phase depending on the chemical composition of the atomic flow. To study these compounds, it was necessary to consider the Cr-Ga-C system. According to the effective heat of formation model, each reaction of a certain phase formation can be characterized by enthalpy [2]. To find out the most favorable phases, it was necessary to calculate the enthalpy of all possible reactions. Thus, the task was to sort through all possible reactions between pure elements available in various ratios, in particular, in the ratio corresponding to the given MAX-phase stoichiometry, i.e. Cr:Ga:C=2:1: 1. Moreover, it is considered that the density of near-coincidence sites [3,4] for interfaces between MAX-phase, thermodynamically favourable competing phases and MgO(111) surface shows a role of the interface in the determination of the structural quality of the MAX-phase thin film grown on MgO(111).
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Pressure measurement inside non-sealed equipment bay of the geostationary spacecraft
Scientific article
The equipment of the non-sealed spacecraft is functioning during the operation phase in the envi-ronment that includes the equipment bay inherent atmosphere. JSC “ISS” together with MAI have developed and implemented in software a mathematical model for the pressure dynamics estimation of the equipment bay inherent atmosphere and for the design parameters selection and construction of the ventilation openings of the non-hermetic equipment bay. The pressure drop dynamics estimation of the equipment bay inherent atmosphere was also carried out according to the developed model. A block of the pressure sensors (joint development of ISS and Novosibirsk State University) was in-tegrated into the geostationary spacecraft for the in-situ pressure measurement inside the non-hermetic equipment bay during the operation. This block consists of two sensors: a semiconductor sensor based on MEMS- technology (micro-electromechanical system) and an inverse magnetron sen-sor with the cold cathode. The pressure sensor unit provides the pressure measurement from 790 up to 1∙108 mm Hg. The authors present the results of pressure measurements inside the non-hermetic equipment bay during the first six months of the spacecraft operation on the geostationary orbit. This article also compares the in-situ pressure measurement results and the calculated pressure drop obtained using the mathematical model for the non-hermetic equipment bay spacecraft.
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Production of finly despersed powder from graphite by electrolysis
Scientific article
Multifunctional coating is a multi-layer structure applied to the surface of an aircraft to protect it from external influences. The main tasks of the multifunctional coating are: restoration of properties, overall dimensions, mass of the surface of the product, which were violated under operating conditions; changing the initial physical, mechanical and chemical properties of the product surface to ensure the specified operating conditions. Today multifunctional coatings based on micro glass spheres with applied tungsten are widely used in aerospace engineering. However, this coating has a number of disadvantages: the coating layers heterogeneity; the composition contains a harmful and dangerous component – a fluorone dye. In this article it is suggested to replace the main component of a multifunctional coating with finely dispersed graphite powder obtained by electrolysis. For this purpose, the equipment based on the principle of a diaphragm electrolyzer was constructed. The main elements of the device are a stainless steel cathode and a graphite anode immersed in an aqueous solution. As a result of anodic processes, a finely dispersed graphite powder was obtained. The average particle size of the resulting graphite particles is 4 microns. This finely dispersed graphite powder can be used as the main component of a multifunctional coating in aircraft, since it has an even homogeneous structure, as well as higher values of the main mechanical properties of a multifunctional coating.
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Prospects for the development of charger-discharge devices of spacecraft power supply systems
Scientific article
Power supply system (PSS) is designed to ensure uninterrupted autonomous power supply of on-board equipment in all modes and at all stages during the active life of spacecraft. Lots of PSS makes up a significant proportion of the mass spacecraft and improvement of specific energy characteristics of PSS leads to a synergistic effect when the mass and energy consumption resources available for the payload are simultaneously increased, which increases efficiency of spacecraft generally. The article considers the evolution of structural and circuit solutions for PSS spacecraft, its energyconverting equipment and the effect of these changes on energy-mass characteristics of PSS. It is shown that a significant effect on energy and mass characteristics of PSS provide structural and circuit design solutions for charging and discharging devices of energy-converting equipment and the choice of voltage value of recharging batteries (RB). The development of the element base, the creation of programmable digital devices capable of functioning under the influence of space factors and the emergence of new circuit design and management solutions for pulse converters that have occurred in the last decade opens up new opportunities for improvement of the PSS of spacecraft. In the article as a chagrining and discharging device of PSS a pulse voltage converter (PVC) with a new modulation strategy is reviewed, with the ability to reverse the flow of energy and the ability to work in a step-up mode with high efficiency. Its application as a single charger-discharge device (CDD) allows for a significant improvement in performance of CDD and PSS in general, such as efficiency, energy mass, reliability and a number of others. Ability of PVC to reverse the flow of energy and the possibility of working in a step-up mode opens up the possibility to abandon the use of RB with a voltage lower than the voltage at the main output of PSS and switch to using RB with an average discharge voltage close to the voltage at the main output of PSS. Such a structural and circuit design solution of CDD and RB will allow to increase efficiency of CDD up to 99 % and additionally improve energy and mass characteristics of PSS.
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Scientific article
Changing the low-voltage level of the output load power bus (27–28 V) in the power supply system (PSS) of the spacecraft (SC) to a high-voltage (100 V) allowed us to significantly reduce the SC mass in connection with the reduction in the mass of cables and energy converting equipment (ECE). However, a number of problems have arisen related to the difficulty of matching the increased voltage levels of energy sources and loads, taking into account the necessary level of reliability of the PSS. Therefore, the issues of choosing the PSS structure and methods for developing ECE are relevant and priority task facing their developers. To date, in the field of development and creation of high-voltage high-power PSS of SC, a promising direction is their design based on integrated ECE modules, in particular, on the basis of modules of charge-discharge regulators (CDR) of accumulator batteries (AB). In the article, a calculation and comparative analysis of the SC PSS structures with the connection of the CDR module to the solar battery (SB) bus and with the connection of the CDR module to the output load power bus is performed. In the course of analysis of the results obtained, it was found that both options for the PSS implementation can be optimal depending on the given curve of the SC load and the requirements for the PSS for specific energy, weightdimension and other characteristics. The final choice of the SC PSS structure should be made subject to the specific power of the ECE and the subsequent calculation of the weight-dimension characteristics of the alternative PSS. Simulation of two options for the implementation of the AB CDR module was carried out: a push-pull converter with one inductor and a Weinberg converter with a magnetically coupled inductor and an additional power diode. It is established that both investigated options can be used in the development and creation of the CDR module of the highvoltage PSS of spacecraft. However, the design of CDR module based on the Weinberg converter can significantly reduce the values of the used inductors and output capacitors subject to the required levels of output voltage ripple.
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Prospects of application of the combined storage space application
Scientific article
Combined energy storage systems are widely used as part of renewable sources in the manufacturing industry, transportation infrastructure, space engineering, and other industries. This trend is due to their higher reliability and efficiency than that of power supplies made of the same type of cells, which can be observed, in particular, in devices for space applications, where power cells are subject to higher requirements for the range of operating temperatures, as well as for input and output characteristics. The article describes the development of the structure of a portable combined energy storage device based on a block of supercapacitors and batteries with a charge and discharge control system, with a scalable (based on the components used) spectrum of input characteristics and a wide range of operating temperatures. The authors presented a mathematical model of a combined energy storage device developed in the Simulink environment, which makes it possible to assess the performance capabilities of the proposed structure by analyzing the different modes of operation of the circuit. Such a device can be used in conditions of extremely low charging currents. For example, if the solar panels are shaded or their spatial orientation is sub-optimal, high-capacity lithium-ion batteries cannot be charged correctly. Also, the advantages of combined electricity storage structures include their operability over a wide temperature range thanks to the ability of supercapacitors to retain their charge even at low temperatures. The article also shows the printed circuit assembly in the form of a 3D model obtained by designing the device circuit in Altium Designer 17 CAD; the results of research and performance testing of a physically implemented combined energy storage device are shown, which confirm its performance characteristics on the example of one of the component modules of the prototype satellite platform CubeSat; the article also provides recommendations for the possible application of such devices and highlights prospects for the application of combined energy storage devices in actuating elements of large flexible spacecraft.
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Qualitative features and discontinuous solutions of ideal plasticity equations
Scientific article
A homotopy of solutions of the well-known Prandtl and Nadai solutions is constructed, i. e., a continuous transformation of one solution into another. This transformation occurs under the influence of a group of continuous transformations allowed by the system of ideal plasticity. In this case, it is possible to observe the evolution of the characteristics of the system, which is determined by the group parameter A. For a = 1, the characteristics of the Prandtl solution are obtained. For a = 0, these are the characteristics of the Nadai solution. At a ≈ 0.47, the characteristics of the first family begin to overlap and voltage gaps occur. In the article, a stress rupture line is constructed. To find the conditions for the occurrence of discontinuities, a qualitative study of the equations of characteristics of the ideal plasticity system was carried out, which made it possible to formulate a condition sufficient for the intersection of characteristics of one family. To illustrate the formulated condition, a program was developed for constructing the characteristics of the Cauchy problem of ideal plasticity equations based on conservation laws. The program was implemented in the Maple environment. The program was tested on the exact solutions of Prandtl and Nadai, the error did not exceed 10–8. Numerical and analytical solutions of boundary value problems were constructed when a sufficient condition on the boundary was not fulfilled. It is shown that in this case the characteristics of the first family intersect and discontinuity lines appear.
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Radar stations as a means of ensuring the security of critical information infrastructure
Scientific article
The paper systematizes the main characteristics of radar stations as a means of ensuring the security of critical information infrastructure. The main types of radar stations are analyzed. It is shown that the dom-inant type among radars are pulse radars of the centimeter and millimeter ranges, which use a single an-tenna, are quite simple and ergonomic when used for their intended purpose. The concepts of tactical and technical characteristics of radar stations are analyzed. The features of the main tactical characteristic – the range of the radar station are considered. It is shown that in order to determine the target detection range, taking into account the influence of environmental conditions and terrain (at the location of the ra-dar station), it is necessary to use a system of equations containing the dependences of the detection ranges of energy, geometric, expected and actual (statistical). The correspondence of analytical calculations to actual results makes it possible to assess the reliability of assumptions about the reflecting properties of goals in various conditions of the situation while ensuring the security of critical information infrastruc-ture.
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Radiation conditions in medium circular orbit during the extreme magnetic storm in may 2024
Scientific article
This article describes the results of monitoring the radiation situation in a medium circular orbit, obtained from the data of the experimental dose control complex (EDCC) of the spacecraft, devel-oped by JSC “Reshetnev”, with a circular orbit at an altitude of H = 8070 km. The article compares the experimentally obtained EDCC data with the calculated data, obtained during flight operation over two years of research. It should be noted that this orbit is poorly studied by Russian spacecraft developers in terms of the impact of space factors. Also considers the effect of the extreme geomagnetic disturbance in May 2024 on the rate of accumulation of the absorbed dose. The method of conducting the experiment consists of creating different conditions of mass protection for each of the nine sensors. The mass protection is varied by installing a steel grid with different cell thick-nesses. Thus, each sensitive element is in unique irradiation conditions – mass protection weakens the flux of ionizing radiation and changes its spectrum (differently for each type of radiation). When developing a new type of orbit for spacecraft operation, the task of ensuring the resistance of on-board equipment and the spacecraft as a whole to the effects of ionizing radiation factors of outer space, typical for this orbit, is relevant. For this, experimental confirmation or refinement of the calculated radia-tion model of impact based on the obtained in-kind data is necessary. The main task solved in the article is to monitor the levels of the integral accumulated dose behind various protections when exposed to ionizing radiation of outer space at an orbit of 8070 km and to compare the results of experimental data with the calculated estimates carried out according to OST134-1044-2007. The article reflects the results of long-term measurements of the absorbed dose of ionizing radiation for a spacecraft with such an orbit. As a result of the measurements, it was established that after an extreme magnetic storm, there is a significant increase in the rate of dose accumulation. This led to the dose rec-orded for 722 days exceeding the calculated value.
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Real-time carrier rocket mission control using space relay system
Scientific article
One of the purposes of the multifunctional space relay system “Luch” is telemetry provision for the timely control of launches from the “Vostochniy” spaceport. Launch vehicles and upper stage units have special high-speed and lowspeed relay user equipment for telemetry relaying using the relay system “Luch”. This article is about special programs for processing such kind of telemetry at the Mission Control Centre (MCC) of the federal state unitary enterprise "Central Research Institute for Machine Building" (TsNIIMASH) for mission launch control. These programs are the part of telemetry processing software-hardware system of the MCC. Their purpose is real-time reception, processing and depicting results of processing telemetry data from high-speed and low-speed relay user equipment. This article contains description of the telemetry structure, transmission scheme and description of telemetry reception and processing approach based on the specific characteristics of such kind of telemetry. It contains information about tasks, solved by the MCC telemetry complex for giving timely, objective and correct information about a launch process as well. Created programs, processing algorithms and representation forms of the results of telemetry processing successfully provided missions control of the launches of the spacecraft “Kanopus-V-IK”, “Meteor-M”№2-1 in 2017, “Kanopus-V” №3, 4 in 2018. We propose to use developed programs for telemetry
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Scientific article
Inspection of underwater objects, such as underwater archaeological sites, sunken technical objects, and un-der water located technical structures, requires the use of specially trained divers, manned or unmanned, re-motely operated or autonomous underwater vehicles. A relatively rarely used design for such underwater vehicles is a design in the form of a quadrotor with posi-tive buoyancy. This article discusses the design and the control system of the remotely operated underwater vehicle in the form of a quadrotor. The aim of the work is the selection and justification of the shape of the vehicle, the selection of the optimal structure of the control system with the expectation of the subsequent use of the vehicle as an au-tonomous one. The potential advantages of the selected design in the form of a quadcopter with a cylindrical body are de-scribed, in particular, the large volume of the sealed space of the vehicle, the possibility of installing capacious power sources, the potential for stabilizing the vehicle in a given position if there is a current at the place of work. The sealed case of the device is designed to place control electronics, power electronics and battery power of the device. The selection and justification of the shape of the sealed enclosure were made using a hydrostatic modeling apparatus and theoretical mechanics. A solid cylinder made of polycarbonate was selected as a form of the sealed housing of the vehicle. The advantage of the selected form in comparison with the parallelepiped-shaped case is shown under the condition of the same material parameters. The control system of the device includes software and hardware components. The choice of hardware com-ponents is justified, their key characteristics are described. As the control device of the top level, a single board computer (SBC, Single Board Computer) Orange Pi PC was selected, the direct control of the motor of the vehi-cle is performed using the Cortex-M3 microcontroller. The software architecture of the device is described. The choice of architecture is determined by the requirements of poorly connected components (which makes it easy to replace particular software elements without the need to modify the other elements), the simplicity of the potential replacement of the top-level control modules (which potentially allows switching from a remote control model to an autonomous control model). Some software components are described. The control system is implemented with the high-level lan-guage Python version 3.7, the basis of the control mechanism is message passing, the MQTT protocol maintained by the Mosquitto server is selected as a messaging mechanism. Testing of the vehicle was carried out in pools with standing water and with a simulated current. Testing showed the need to gain experience to control the underwater vehicle. The study will allow us to further develop a new version of the underwater vehicle, taking into account the wishes and identified problems.
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Scientific article
This article presents some of the main parameters of metal mesh that affect the radio-reflective properties of reflectors and the technology for attaining these parameters by controlling the tension capacity of the mesh sheet at various stages of the radio-reflective surface manufacturing. The article also includes a brief overview of the developed methods (applied at the RESHETNEV JSC) of measuring and controlling the tension capacity of spacecraft reflectors with mesh shields, along with the analysis of the shortcomings revealed in the application of these methods. The authors introduce a new method of the tension capacity control based on the local deformation of the metal mesh by pressure of the air drawn through its surface. There are the results of development and testing of the metod, and of a model device for controlling the mesh tension capacity. The purpose of the research is to determine the operability of the device and the ways of its possible application in controlling the tension of the mesh-made reflectors ready for operation. The developed method and the model device for its application allow in-process control of the mesh tension at any spatial position of the mesh sheet. There is an analysis of possible application prospects of the method in rocket and space industry for manufacturing radio-reflecting surfaces of spacecraft antennas. According to the results of the research, the ratio of the mesh tension capacity to the pressure of the air drawn through the sheet was determined. The need for further improvement of the designed device aimed at increasing the measurement data accuracy was also pointed out.. In case the laboratory testing of the upgraded device for controlling the mesh tension capacity proves successful, further tests will be carried out in the process of sheet cutting and in the reflector shield manufacture.
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Scientific article
The paper presents the results of studying the shielding properties of thin transparent films in single-walled carbon nanotubes on flexible substrates of polyethylene terephthalate. The films were formed by spraying colloidal solution on single-walled carbon nanotubes. The film thickness was determined by the volume of the sprayed colloidal solution and was measured using transmission electron microscopy in a cross-section mode. The morphology and structural quality of the films were studied by electron microscopy, optical spectroscopy, and Raman spectroscopy. The results showed the high structural quality of the material. According to Raman spectroscopy, the ratio of peaks intensities G / D is 23.4, which is the evidence of a significant predominance of carbon in the sp2 hybridization. It is typical for graphitelike systems and, in particular, carbon nanotubes. The spectral dependences of the transmission and reflection coefficients of radio waves in the K range of 18–26.5 GHz were studied. Absorption of radiation is the dominant shielding mechanism. Increasing the film thickness from 15.9 to 56.1 nm is accompanied by decreasing the surface resistance from 971 to 226 Ohm / sq, while optical transparency decreases from 93.58 to 76.71 %. Shielding efficiency increases from 2.29 to 6.6 dB, increasing the proportion of absorbed radiation from 34.6 to 51.2 % at a frequency of 18 GHz. This indicates the prospects for the use of films as electromagnetic shielding and anti-icing coatings in the aerospace industry.
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Scientific article
Today, there are many approaches to developing parallel programs. It is considered that it is more efficient to write such programs for a particular computing system. The article proposes to ignore the features of a particular computing system and outline plans for the development of a certain automated system that allows trying to improve code efficiency by developing programs with unlimited parallelism, as well as explore the possibility of developing more efficient programs using the restrictions imposed on maximum parallelism. This approach was demonstrated on the example of the analysis of various matrix multiplication algorithms. As a mathematical apparatus, the study considered various approaches to the description of algorithms to increase their implementation, including an approach based on unlimited parallelism and, also, an approach based on various restrictions on parallelism is proposed. In the course of the work, sequential and parallel methods of matrix multiplication were studied in detail, including tape and block algorithms. As a result of the study, various matrix multiplication methods (sequential, with left and right recursion, parallel methods) were studied and more effective ones were found in terms of the resources used and the restrictions imposed on parallelism. A sequential method and a cascade summation scheme were analyzed and proposed as possible ways of convolving the results of solving the problem obtained after the decomposition stage. Also, a number of programs with different levels of parallelism were developed and implemented in the functional-stream parallel programming language. In the future, such transformations can be carried out formally, relying on a knowledge base and a language that allows equivalent transformations of the original program in accordance with the axioms and algebra of transformations laid down in it, as well as replacing functions that are equivalent in results and have different levels of parallelization. These studies can be used to increase the efficiency of developed programs in terms of resource use in many branches of science, including in the field of software development for the needs of astronomy and rocket science.
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Scientific article
The article provides an overview of current methods for measuring and controlling the tension force of the material of the spacecraft metal-mesh reflectors. The purpose of the research: to obtain the most accu-rate results of measuring the mesh tension. Based on the review, a comparative analysis of the advantages and disadvantages of each of the considered methods was carried out, when measuring the tension force on mesh for large-sized transformable spacecraft reflectors. In the article considered the methods of force measurement: photo method, the operation principle of which consists in the sequential photographing of a mesh on reflector frame certain zones; a method based on pattern recognition, similar to the photo method, but using an information and measurement system with a given information processing algorithm; a meth-od based on local membrane deformation, related to the contact type, in which the mesh tension measure-ment is defined as a reaction from the impact of physical force on the mesh surface; a method based on the influence of sound waves impact, which is based on the influence of sound waves impact on the mesh sur-face. The experimental part of the research described in the article includes the measurement of the mesh tension by the resonance method, as the most optimal method according to the analysis. The prospects of possible use of the resonance method in the aerospace industry of radio-reflecting surfaces of spacecraft antennas are proposed and analyzed. According to the results of the conducted research, the dependence of tension force of mesh is established on the sound vibrations frequency affecting the mesh, at which reso-nance occurs.
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