Статьи журнала - Siberian Aerospace Journal
Все статьи: 330
Increasing the capabilities of a test ballistic missile to separate test objects
Статья научная
The subject of this study is the trajectory characteristics of the long-range test ballistic missile (TBM). The purpose of the study is to increase the capabilities of TBM in separating test object (TO). At the same time, as a generalized quantitative measure of this increasing, the post-boost vehicle (PBV) fuel reserve consumed for separation of TO is studied. The design-ballistic task of rationalizing the distribution of the available fuel of the TBM PBV between the following main characteristic section of its flight has been set and numerically and analytically solved: final sustainer stage undershoot compensation; turns with subsequent angular stabilization, retreats and lead away; TO disconnection (separation section). As a result, it is shown that without reducing the quality of TBM launch tasks, it is permissible to redistribute the consumed fuel of the PBV between these section relative to the distribution for a standard ballistic missile (SBM), leading to a significant increase in its reserve consumed in the section of disconnection of the TO (when flying along the ballistic vertical). At the same time, the purpose of the study is achieved – the capabilities of the TBM in the separation of the TO are increased, which, while direct planning of launches is evaluating, can be expressed in an increase in the number and/or total mass of the TO and/or an increase in speed or time intervals in the order of sequential disconnections of the TO. The given numerical examples (using a converted three-stage SBM as a TBM) also show a significant dependence of the amount of fuel increment of the PBV consumed at the TO disconnections of the trajectory conditions of test launches (the corresponding initial data (ID) for calculations are borrowed from the author’s previously published work): length of the route; kinematic parameters of launch at the moment of independent PBV flight beginning determined by the launch task. During the study, methods of flight theory and design ballistics of LR (long range) missiles were used. As a conclusion, it can be noted that the considered task and methods for its solution can be useful (of course, taking into account the necessary specialized improvements) in works of the executive ballistics level when planning and evaluating the result of TBM launches.
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Increasing the period of active use of on-board electronic equipment of spacecraft
Статья научная
For electronic equipment of space systems, and primarily memory devices, the task of protection from the effects of ionizing cosmic radiation and other external factors that distort stored and processed information is relevant. This paper proposes a holographic coding method that allows to restore information in the event of a large number of errors. The method is based on recording into memory, instead of the original digital hologram data, a virtual digital object corresponding to a data block. The divisibility property of a hologram is used, which makes it possible to reconstruct a recorded data block from its fragment. The achieved level of noise immunity is determined by the size of the hologram. For an 8-bit data block, recording a 256-bit hologram provides information recovery if 75 % of the recorded hologram is lost. The developed decoder corrects a package of dependent (grouping) errors that distort all bits of the hologram. The number of random independent errors that the decoder corrects can be up to 40 % of the recorded information. The information storage system, resistant to ionizing radiation, is a memory array of increased capacity, taking into account the selected redundancy factor, and a memory controller that performs holographic encoding when recording information and decoding with automatic error correction when reading information. The operating algorithm of the controller itself can be implemented in the form of a programmable logic integrated circuit, or stored in a read-only memory device that is not affected by ionizing radiation.
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Increasing the positioning accuracy of the GLONASS system
Статья научная
The accuracy of determining coordinates in global positioning systems is determined by the number of satellites simultaneously visible to the consumer's navigation equipment. Over most of the earth's surface, there are up to 11 GLONASS satellites above the horizon at the same time, but the signal-to-noise ratio in the communication channel required for error-free information reception is often ensured only for 2-4 satellites. To improve the positioning accuracy, it is proposed to use the holographic noise-immune coding method based on the holographic representation of the digital signal. The message coding process is a mathematical modeling of a hologram created in virtual space by a wave from the input signal source. It is shown that the holographic representation of the signal has significantly greater noise immunity and allows restoring the original digital combination when most of the code message is lost and when the coded signal is distorted by noise several times exceeding the signal level. The studies have shown that the introduction of holographic coding in the GLONASS satellite communication channel will enable consumer navigation equipment to receive information from a larger number of satellites, which will significantly improve the positioning accuracy. In a common situation where the required signal-to-noise ratio is maintained for only 4 GLONASS satellites, the positioning error exceeds 10 meters. Using holographic coding in the same situation, information from 9 satellites will be decoded without error, and the positioning error will be about 2 meters.
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Статья научная
Liquid-propellant rocket engines (LPRE), operating according to a gas-free generator scheme, are used for the upper stages of launch vehicles and upper stages. In engines of this scheme, only cryogenic fuel is used, which provides a high engine STI. Also, a distinctive feature is the absence of a gas generator, the combustion generators of which feed the turbine of the main turbopump unit. In the gas-free LPRE scheme, the turbine is driven by gas-return hydrogen heated in the cooling loop. Therefore, the high parameters of the LRE, such as the pressure in the CC, the thrust of the engine and the specific thrust pulse depend on the effective heat removal from the firing wall of the combustion chamber and the intensification of heat ex-change in the cooling path. There is a number of solutions that allow to increase the amount of heat transferred to the refrigerant in the inter-shirt space. Therefore, the search for an optimal cooling scheme and promising design solutions for the intensification of heat transfer in the engine cooling path will allow us to determine the high param-eters of the LPRE. This article discusses the effect on the thermal state of the combustion chamber of the gas fins installed on the firing wall of the engine. Gas fins belong to the developed heat exchange surfaces and increase the area of the side surface of the combustion chamber. With the help of the developed mathematical model of the cooling chamber of a gas-free LRE, extremes in the intensification of heat exchange in the cooling path have been identified. The dependences of the specific thrust impulse of the engine on the pressure in the combustion chamber and the geometric dimensions of the engine are also obtained.
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Influence of a constant electric field on the adsorption purification of water from iron ions
Статья научная
Using electrochemical action (ECA) to treat water was first proposed in UK in 1889. At present, many methods of ECA are known (electro flotation, electro coagulation, electro osmosis, electrophoresis, etc.). In the production of rocket and space technology, galvanic technologies are used, as a result of which waste water is contaminated with metal ions. Known methods of wastewater treatment do not allow to ensure the maximum permissible concentration of metal ions in treated water, or are expensive or difficult to operate in industry. Iron ions are among the most polluting components of wastewater of most industries. So increased control and the development of effective methods of wastewater treatment are necessary. Iron affects the intensity of phytoplankton development and the qualitative composition of microflora in reservoirs. The toxicity of iron compounds in water depends on the hydrogen index of water. The alkaline environment dramatically increases the risk of fish poisoning, as in such conditions, iron hydroxides are formed, which are deposited on the gills, clog and corrode them. In addition, iron compounds bind oxygen dissolved in water, which leads to the mass death of fish and other hydrobionts. The article presents the method of conducting experiments, the methods of sorption, electrochemical and combined water treatment, including electrochemical action and adsorption. The results of studies of these methods of water purification from iron ions are presented. The dependence of the degree of purification on the electric field strength, interelectrode distance and water treatment time is revealed. With an electric field strength of 5.16 V/mm, a temperature of 20–22 °C using quartz sand as an adsorbent and a processing time of 1 minute, the concentration of iron ions decreased from 2.5 to 0.25 mg/l (at MPC = 0.3 mg/l). The proposed combined cleaning method requires inexpensive and affordable materials and is easy to operate.
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Статья научная
The properties of a solid solution of thulium-substituted manganese sulfide prepared by melting the ini-tial pure samples of manganese sulfide and thulium sulfide are studied. X-ray diffraction analysis was car-ried out. The face-centered cubic lattice is determined, and the decrease in the intensity of the peaks is found. Dielectric permittivity was measured in the frequency range 102–106 Hz and temperatures 300–500 K in magnetic fields up to 12 kOe in TmxMn1-xS solid solutions (0 < x < 0.15). From the frequency depend-ence of the permittivity, the relaxation time and the relaxation mechanism of the dipole moments are found. The leakage current is excluded, and the contribution of migration polarization due to charges in the re-gion with chemical phase separation is estimated. The real and imaginary components of the permittivity of TmxMn1-xS samples are described in the Debye model. The maximum of the imaginary component of the permittivity shifts towards higher frequencies upon heating, and the relaxation time is described by the Ar-rhenius function. Dielectric losses are caused by electron-phonon interaction. The frequency of the crosso-ver from Debye relaxation to relaxation conduction associated with the absorption and emission of pho-nons is found. The crossover frequency increases as the sample is heated according to a power law. In a magnetic field, the permittivity decreases and the largest change of 2.5 % is achieved at T = 450 K. At oth-er temperatures, the magnetocapacitance does not exceed 0.5 %. The shift of the maximum of the imagi-nary component of the permittivity to low frequencies in a magnetic field leads to a change in the sign of dielectric losses from positive to negative. A qualitative difference in ε(ω) is established in the vicinity of the concentration of thulium ion flow through the FCC lattice, where the permittivity is not described in the Debye model and there is no magnetocapacitance. The mechanism for reducing dielectric losses in a mag-netic field is determined.
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Influence of plasma jets of electric jet engines on spacecraft functional characteristics
Статья научная
The issues of compatibility of correcting electric jet engines (EJE) and large-size transformable antennas (LTA) used in high-orbit communication satellites are considered. The paper deals with the erosive and polluting effect of EJE jets interacting with knitted mesh material (grid mesh), which is used for manufacturing LTA reflectors. The erosive effect of the EJE jets on the LTA mesh is characterized by the fact that the angles of ions incidence on the surface of the threads in the mesh are in the range from 0 to 90, i. e. such effect takes place at practically any angle of ions incidence on the mesh surface. The research includes both mathematical description of physical processes and conducting a wide series of experiments, which makes it possible to achieve the necessary reliability of the results. It has been established that the effect of plasma jets of correcting engines can lead to significant sputtering of the reflecting coating from the surface of a large-size antenna reflector. The authors obtained experimental data on the degradation of the reflection coefficient of electromagnetic radiation from the mesh, depending on the degree of plasma jet influence. It was found that the sputtering of reflecting coating from the surface of threads does not significantly affect the reflection coefficient. The sputtering of the coating at the points of threads contact is much more significant. Strong dependence of the reflection coefficient on the type of mesh weaving was also found. The mechanism of sputtering products deposition on reflecting coatings of the thermal control system radiators was investigated. The results of calculations of the sputtering coefficient and the sputtering indicatrix of the reflecting coating applied to the mesh threads were obtained. The degradation of the functional characteristics of thermoregulatory coatings (TRC) during the deposition of thin films of gold, which is one of the possible materials for a reflecting coating, was experimentally determined. Estimates of the maximum permissible level of TRC contamination were obtained. It is shown that, subject to the relevant design rules, it is possible to use EJE and LTA together in high-orbit communication satellites.
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Статья научная
Due to the absorption of solar energy in chloroplasts – green plastids, solar energy is converted into the energy of chemical bonds. Studying the processes of photosynthesis and increasing its efficiency is relevant for the development of closed life support systems, during long flights in space as well. Chloroplasts are filled with stacks of highly ordered thylakoid membranes (grana). Pigment-protein photosynthetic complexes are located on the border of these membranes. For a long time, the structural characteristics of chloroplasts were not given due attention and they were studied as isotropic substances, but in recent years it has been shown that they have anisotropic properties and a high conversion coefficient during charge separation. In this work, an approach was proposed for a more accurate spatial determination of grana in plant chloroplasts and for determining the size of a single unit. Thylakoid membranes and the boundaries of the facet consisting of them are clearly visible in an electron microscope if the electron beam is directed strictly perpendicularly. It was noticed that when the stage is rotated, different regions of the membranes become either blurred or more distinct, which suggests that the grana in chloroplasts are not located in the same plane. Also, a comparison was made of the influence of different external conditions on the chloroplast structure of a plant, not only through a comparison of morphological characteristics, but also through numerical modeling and comparison of the objects spectral properties. For numerical simulation, periodic lattices were determined for the main structural units of chloroplasts of different samples. On the basis of these gratings, the transmission spectra were calculated using the transfer matrix method. Also, the obtained values of the electromagnetic wave along the lattice made it possible to calculate the graphs of the density of photon states. The results of the calculation method of plots of the density of photon states based on the structure of chloroplasts made it possible not only to assess the possible efficiency of photosynthesis, but also to directly relate these models to the external conditions affecting the plant.
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Influence of the magnetic field on transport properties of holmium – manganese sulfide
Статья научная
Holmium-manganese sulfide with giant magnetoresistance refers to new magnetic sulfide compounds of holmium and manganese that have the effect of giant magnetoresistance (i. e., with special magnetoelectric properties), which can be used as components of sensor technology, magnetic memory, and spintronics. The technology of manufacturing polycrystals HoXMn1-XS grown by crystallization from the melt of the obtained powdered sulfides with a purity not lower than 99,9 %, in glass-carbon crucibles and a quartz reactor in an argon atmosphere is presented. According to the results of x-ray diffraction analysis, HoXMn1-XS holmium-manganese sulfides have a HCC structure of the NaCl type. As the degree of cationic substitution increases, the unit cell parameter increases linearly with the concentration. No concomitant impurity phases are detected in the synthesized samples. To determine the state of the spin glass, magnetic moment measurements are conducted at several frequencies ω = 1 kHz, 10 kHz and 100 kHz. The dependence of magnetic characteristics on the frequency of measurements is found. The damping of the magnetic moment and its increase with a decrease in temperature is reviled, which is connected with the formation of metastable States. Measurements of electrical resistance without a field and in a magnetic field are conducted. Anomalies in the temperature dependence of the conductivity are found. A change in the magnetoresistance sign is detected with the increase of temperature below and above room temperature.
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Information-measuring system of pyrometric type for small-sized unmanned aircraft
Статья научная
A new trend of science and technology is now rapidly developing both in Russia and abroad – the development of miniature unmanned aerial vehicles. The key system of on-board control equipment (avionics) of an unmanned aerial vehicle (UAV) is the orientation system for determining UAV attitude relative to reference system. In small-size UAV, we can meet the application of strapdown attitude reference systems, magnetometric, pyrometric, video systems, etc. Rapid development of mini- and micro-UAVs requires the development of information-measuring systems (operating on different physical principles) in order to determine UAV attitude parameters in flight. With UAV mass and wingspan reduction, there are growing requirements for these systems, concerning the accuracy of positioning parameters and more compact dimensions. Manufacturing of most information-measuring and control systems of manned aircraft and heavy UAVs rely on traditionally used gyroscopes and accelerometers. They are complex fine-mechanics instruments of considerable power consumption, rather large size, weight and high cost. A significant improvement of the accuracy in UAV angular coordinates determination is achieved by integrating orientation systems of various types. The use of GPS / GLONASS signals also improves the accuracy and reliability of determining UAV angular coordinates and supplies the additional function of measuring its geographical coordinates.
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Статья научная
The possibilities of creating an innovative educational and scientific center for monitoring forest resources in Siberia on the basis of the Department of Space Facilities and Technologies of the Reshetnev Siberian State University of Science and Technology are discussed, with the aim of training highly qualified engineering personnel and conducting promising scientific research in the field of monitoring, modeling, forecasting and management of forest resources. Methodological solutions and algorithms for threedimensional modeling of forest structure and dynamics based on laser scanning data, digital aerial and space photography are proposed. These methods contribute to operational monitoring and can significantly reduce the cost of monitoring the condition and use of forest resources over the vast territory of Siberia. Remote sensing data is presented in the form of a geotransformed database and digital photo map, compatible in formats with computer-aided design systems and with the main geographic information systems – ArcView, ArcINFO, MapINFO. The innovative monitoring center will be used for operational state control and monitoring of forest management, the state of forest lands, forest management and forest inventory, solving problems of ecology and environmental management, geoecology, formation of a forest resource inventory, aerospace methods for studying natural resources and territories, information technology. Solving these problems will allow for the training of highly qualified specialists. The center's specialists plan to create information technologies for remote sensing of natural objects with the aim of import substitution of foreign software products. The main scientific directions of the created center: development and research of methods for system analysis of large-scale multidimensional remote sensing data based on nonparametric decision-making algorithms and parallel computing technologies; testing hypotheses about the distributions of large-volume remote sensing data based on nonparametric nuclear-type pattern recognition algorithms; detection of compact groups of large-volume remote sensing data corresponding to unimodal fragments of the joint probability density of multivariate random variables.
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Статья научная
Academician Mikhail Fedorovich Reshetnev is one of the outstanding scientists, designers and production organizers who stood at the origins of the development of rocket and space technology in our country and made a significant contribution to domestic and world cosmonautics. 2024 marks the 100th anniversary of his birth and the 60th anniversary of the first launch of the Kosmos-3 launch vehicle (LV), created under his leadership in the Krasnoyarsk Territory. The article discusses the main stages of design, development work, flight design tests and the launch of mass production of the rocket. It is noted that the creation of the PH was carried out mainly at the production base of the Krasnoyarsk Machine-Building Plant (Krasmash). The most important events related to the organization of the OKB-1 branch, which was then transformed into an independent OKB, are described in chronological order. The role of M. F. Reshetnev’s personality is shown. Reshetnev in solving complex scientific, technical, organizational and production problems of mastering new technology in the Siberian region, remote from the rocket, space and scientific centers of the country. Information is provided on innovative technical solutions developed under the guidance of M. F. Reshetnev during the creation of the Kosmos-3 launch vehicle and its subsequent modification. It is noted that M. F. Reshetnev in his scientific and technical activities constantly received the support of S. P. Korolev and M. K. Yangel, successfully cooperated with the largest design organizations headed by V. P. Glushko, A. M. Isaev, V. G. Sergeev and other well-known leaders and specialists of the rocket and space industry.
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Inter-satellite optical communication link
Статья научная
A two-level system of data transmission in the optical range is considered between a low-orbit spacecraft located in a sun-synchronous orbit and a repeater satellite located in a geostationary orbit. This topic is rather relevant due to the fact that the rapid development of remote sensing satellites resulted in the increase of the amount of transmitted information, which in consequence introduced new requirements for communication systems. The increase of data transmission rate and severization of requirements for communication systems contributed to the development of one of the most promising areas of space communications, based on the information transmission via a laser channel, due to a high energy concentration and a much higher carrier frequency. The prospects for the application of optical communication systems are designated by lower power consumption, dimensional specifications and the mass of the transceiver equipment of the optical range (compared to radiofrequency range systems). The article describes the solution of application of optical communication link between a low-orbit spacecraft and a repeater satellite. The main factors that contribute to the attenuation in the process of signal propagation along the route are presented and analyzed. A model of a communication channel between a low-orbit spacecraft and a repeater satellite is provided for a visual image. Two different approaches of mutual guidance and tracking of laser terminals are described for using beacons and without ones. EDRS foreign system is considered as an analogue. The estimation of the main parameters of the communication link is given. The communication system considered in the article will allow for greater carrier capacity of the data transmission in the optical range between the low-orbit spacecraft and repeater satellite. The application of this system will allow solving problems, including in the interests of any departments and structures of the Ministry of Defense of the Russian Federation, for which the rate of obtaining information is one of the basic requirements for a satellite communication system. The tasks of precise targeting of receiving and transmitting devices arising as a result of narrow beam patterns can be solved with current technical means.
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Interaction of magnetic and dielectric subsystes in a bismuth nodymic ferrite-granate
Статья научная
Bismuth-substituted ferrite garnets possess magneto-optical (MO) properties and are used as spatial light modulators and indicators. The paper studies the influence of magnetic and electric fields on the structural characteristics of thin epitaxial films of bismuth-neodymium ferrite garnet (Bi: NIG) deposited on glass and gallium gadolinium garnet (GGG) substrates. Dynamic properties of polarization, relaxation in a magnetic and electric field are considered, which is an important task for getting a deep insight into the mechanisms of electromagnetic phenomena in solids. Dependence of the magnetostriction coefficient on the magnetic field and dependence of a relative change in the length of the film on the electric field at different temperatures are obtained. A change in the sign of magnetostriction constants with respect to temperature was found. The electric polarization in a periodically applied electric field of 400 V / cm with a frequency of 10 MHz is determined for various magnetic field orientations of 12 kOe and in the absence of a magnetic field. Anisotropy of polarization in a magnetic field and a functional dependence of the polarization relaxation on time are found. These materials can be used as sensors of the magnetic field in a spacecraft.
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Статья научная
Many strategically important sectors of the domestic industry are at the stage of transition to an investment approach to asset management. One of these industries is hydropower, where the current maintenance planning system needs new methods to deliver more efficient results. In general, the planning system for the main equipment (technical impact system) maintenance and repair can be formulated as a scheduling problem. The ant algorithm is of great interest from the point of view of solving the scheduling technical impact problem. Based on the specifics of planning, implementation and factors affecting the maintenance process, a modification of the ant algorithm is proposed. The mathematical description is a methodology for calculating parameters, basic elements of the graph, optimization criteria and constraints. A preparatory stage was also introduced into the solution algorithm, which determines the initial state of the equipment at the vertex K0. The functional model of the technical impact planning process presented in the article can be used to develop a software package within the framework of an innovative approach to asset management for hydropower companies.
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Статья научная
One of the most effective tools of remote sensing and visualization of underwater surfaces and objects are acoustic devices, in particular side-scan sonars (SSSs). Recently, largely due to the emergence of affordable devices, the geography and scope of application of SSSs has been significantly expanded. Meanwhile, despite certain progress achieved in terms of improving and minimizing the SSS hardware, the software used remains, in general, at a basic level, providing the operator mainly with a simple tool for visualizing benthic environments and data recording for further post-processing. Existing experience in SSS exploitation reveals that the key problem of interpreting acoustic images lies in the physical peculiarities of their acquisition. Arguably, attempts to implement methods of automated interpretation of optical images have no perspective. Hence, the objective of this paper is to provide a theoretical and practical background of SSS data interpretation and processing with the objective of further automation of this process. Taking into account the operating conditions of the SSS, in particular the vast areas of water areas - search zones, this problem is one of the key ones for SSS operators. The problem of automating data processing is directly related to the problem of interpreting remote sensing data, including satellite images, geometric distortion of images caused by the physical characteristics of the device and its operating environment, as well as referencing the obtained data to the satellite coordinate system.
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Статья научная
High-precision and reliable inspection of thermal deformations is necessary in terms of simulating the effects of space in the ground-based experimental processing of antennas and mirror systems of spacecrafts. Inspection of objects up to 1.5 m in size is considered in the paper. In practice, it can reach sizes up to 10 m. Requirements for thermal deformation are in range of 10–200 micrometers. The deformable surface is rough (Ra » λoptic). The measurement error, however, should not exceed ± 1 micron. The electronic speckle pattern interferometry (ESPI) method is the most suitable for solving this problem. The method allows to inspection objects with a randomly inhomogeneous surface. The method assumes that it is necessary to calculate the wave phase values from the recorded picture by the digital matrix. It is the phase that contains information about the deformation, and the spatial phase shift method is used to calculate it. One of the measuring systems based on this method is the measuring system PulsESPI (Carl Zeiss Optotechnik GmbH production, Germany). It has a high sensitivity which is about 50 nm. However, this measuring system is designed for single measurements. In this regard, an additional software module for processing and visualization the result of a series of several hundred measurements has been developed. The experimental test bench with a test object has been developed to research the metrological characteristics of the PulsESPI system in accordance with thermal deformations measurements (multiple determinations). The PulsESPI system and the Renishaw XL-80 interferometer introduced into register of measuring instrumentation of Russian Federation were located on different sides of the object 1.5 m in size. As a result of measuring the surface displacement measured by the Renishaw XL-80 interferometer and its corresponding point from the PulsESPI system deformation map are compared. Three types of tests were carried out at the developed bench. The root-mean-square deviation of single measurements was no more than ± 0.2 μm. Error was no more than ± 1 μm when the series of measurements was conducted in which a total strain of 200 μm was obtained. The results obtained suggest the possibility of using this system for high-precision inspection of thermal deformations of large objects.
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Статья научная
The object of the study is a cylindrical mesh shell without a regular structure covering, made of carbon fiber composite material. A distinctive feature of this class of structures is the intersection of families of annular and spiral ribs. Mesh shells are used as power elements of spacecraft, therefore, when designing them, the main re-quirements are a reduction in the mass of the structure, high strength and stiffness characteristics. The re-duction of the shell mass is achieved by varying and selecting the structural and geometric parameters of the ribs. The article considers a set of mesh cylindrical structures of fixed mass. The authors have developed and presented an algorithm for calculating the number of elements of a regular rib structure and calculating the values of geometric parameters of elements of rib families. Two approaches to the formation of rib sys-tems are considered: by changing the heights or thicknesses of the rib structure. A macro has been developed for modeling parametric discrete models of such rib structures in the An-sys Mechanical APD software package. When constructing discrete grid models, a one-dimensional two-node finite element BEAM4 was used. The model was rigidly attached at the nodes along the lower edge, a load was applied to the nodes of the upper edge. Two types of loading were considered. The “non-flight” mode was determined by the axial loading of the shell evenly distributed along the upper edge. Flight mode – additionally took into account the applied moment. The displacement and deformation fields were calculated numerically in the ANSYS finite element package. The article presents the results of a study of the effect of the density of the rib structure on the stability of mesh shells under static axial loading, natural frequencies and waveforms. It is shown that with increasing density, the rib structure becomes thinner. At the same time, the critical load decreases, the values of the natural frequencies of the shells decrease, and the number of waves in the forms increases. The influence of approaches to the modeling of rib structures on the results of numerical calculations is noted.
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Статья научная
We have considered the issues of ensuring the resistance of high-voltage solar battery (SB) of spacecraft to the effects of secondary arc discharges. Research in this area has been going on for more than 50 years, but the answer to all the questions has not yet been found. First of all, this is due to the complexity of the electrophysical processes occurring on the surface of the spacecraft in space and in laboratory conditions. The second reason is the random nature of secondary vacuum arc discharges, which requires the use of special test methods to confirm the effectiveness and reliability of selected design and technological solutions. Tests in conditions close to full-scale conditions do not allow us to solve this problem. We have given a retrospective review of publications on the physical features of secondary arcs arising on SB of spacecraft, the mechanisms of their initiation, experimental research and testing methods. We paid considerable attention to the issues of the occurrence of secondary arc discharges SB of the spacecraft in the conditions of ionospheric plasma and plasma generated by electric propulsion thrusters. We have shown that despite the large amount of accumulated data and knowledge, the transition from low-voltage SB to high-voltage SB remains a difficult scientific and technical problem, which requires additional research to solve. In addition, it is already necessary to start training personnel who possess a wide range of knowledge and are able to work on this topic. To do this, it seems advisable to organize sectoral research, as well as the allocation of targeted funds for the training of highly qualified specialists and their independent research. This approach will make it possible to solve the problem of creating high-voltage SB in the shortest possible time and prepare personnel for the development of this technology.
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Laboratory separator of bulk materials
Статья научная
New materials for spacecraft radiation screens engineering require a fine classification of powder materials by particle size. The article concerns the construction of powder materials laboratory separator. This type of material separation is related to gravity methods. The Moseley laboratory separator serves as the prototype of the construction with table longitudinal shaking and diametrical vibrations by means of buffers during the separation process. The unbalanced oscillator yields deck separation surface harmonic vibrations in all directions. The unbalanced oscillator DC motor voltage control gradually alters the vibration frequency and supports finer separation of the material. A power pipe enables to conduct perpetual separation process. In prototype, in contrast, up to 100 g weight is processed for up to 5 minutes. To improve the materials fine and small classes separation efficiency, riffles are made on the separation surface, which determine the places of concentration of material particles. As a result of the conducted researches for elimination of the secondary circulation flows, a system of diametrical reefing is worked out: the riffle is approximately equal to the maximum particle size of the separated material and is equal to 0.2 mm in this construction; the distance between riffles is equal to 50 mm, the tilt angle is 80 degrees relative to the deck longitudinal side. The particle motion depends on the inclination angle of the separation surface. Large particles move upwards at angles of up to 5 degrees, and downwards at angles higher than 5 degrees. Vibration frequency and amplitude alteration, as well as adjusting the inclination angle of separation surface enables to move and adjust the speed of different properties and sizes of test material. The laboratory separator work is based on the physical effects, which enable to vary the location of the power pipe. This fact allows the construction to be adapted to a variety of specific conditions and expands the construction sphere. The separator construction is simple for production and operation, and can be quickly reconfigured if necessary. The separator portability allows it to be transported.
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