Статьи журнала - Siberian Aerospace Journal
Все статьи: 330
Laser processing of titanium alloys to increase the strength of adhesive joint with cfrp
Статья научная
Titanium alloys are hard-to-bond materials due to the fact that a thin oxide film is always present on their surface, which prevents the formation of interatomic and intermolecular bonds between the adhesive and the substrate. In the load-bearing structures of spacecraft (SC), an adhesive bond between a titanium alloy and a composite material is often used. But the strength of such knots is relatively small compared to the mechanical connection. The purpose of this work is to increase the strength of the adhesive joint, due to laser processing of the working surface of the titanium alloy for gluing. Texturing of the surface of the tita-nium alloy OT-4 was carried out on an ytterbium pulsed fiber laser in 4 processing modes. The treated sur-face was glued with KMU-4 carbon fiber over an area of 300 mm2 using a VK-9 three-component adhesive. The adhesive strength test was carried out on a Eurotest T-50 tensile tester. The test showed that the strength of the laser-treated samples increased by more than 80% relative to the average value of mechan-ical grinding. The highest value of shear strength was shown by samples with laser processing No. 1 and No. 3. This is due to the greatest increase in the area of bonding of the surface, as well as the mechanical locking of the adhesive in the microrelief of the structure. The increase in shear strength caused by laser surface treatment is a mixed effect of increasing surface area, mechanically locking the adhesive, and changing the surface chemistry. The chemical composition of the surface structure under the influence of laser scanning is gradually transformed from Ti and Ti2O3 to crystalline TiO2. The nature of the destruc-tion of the adhesive joint in the samples with laser processing is predominantly cohesive, but samples with the destruction of the carbon fiber material were also observed, that is, the shear stress in the composite material exceeded the adhesive strength. The effect of pretreatment of the composite material on the strength of the adhesive joint was not considered in this work.
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Library of mathematical functions with parallelism at the operational level in the Pythagor language
Статья научная
At present, developed tools and libraries have been designed for imperative and functional programming languages that provide parallelism through processes or threads. There are other alternative approaches to the organization of parallel computing, one of which is implemented in Pythagor – the language of functional-streaming parallel programming, and involves parallelism at the level of operations. The tools of the Pythagor programming language are actively developing, and the repository of predefined functions is expanding. Many mathematical functions have been designed to provide a developer with no less functionality than the math library math.h of the C programming language. A large part of the mathematical functions have been implemented using the Maclaurin’s series. It is both used as an approach of faster and less accurate calculations, in which a predetermined number of elements of the series is calculated without cycles and recursions with the substitution of pre-calculated coefficients in the function code, and as an approach of less rapid and more accurate calculations, in which the elements of the series are calculated dynamically until the desired accuracy is achieved. The development of a library of mathematical functions of a programming language is an applied algorithmic task already implemented in one way or another for a number of existing programming languages. But in many languages, the implementation of algorithms for mathematical functions is hidden from the user, while modern tools of the Pythagor language support an open repository of functions. Additional interest is the possibility of parallelism at the level of operations in the calculation of mathematical formulas in the Pythagor language.
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Статья научная
In this work, an analytical determination of the local heat transfer coefficient in the planes of rotation of gas turbines is carried out using an affine-like model for the distribution of temperature and dynamic spatial boundary layers with a convective component (at Pr < 1). The method of analytical study used in the work led to results close to the experimental values. The problem of determining the thickness of the energy loss is solved using the integral relation of the energy equation of the temperature spatial boundary layer, which makes it possible to integrate the necessary curvature over the surface. The law of heat transfer of the turbulent boundary layer for the rotational motion of the flow and motion according to the law of “solid body” is expressed. Equations are obtained for determining the local heat transfer coefficient by the Stanton criterion for various external flow laws for a power-law velocity distribution in the boundary layer according to the affine-like model of the temperature boundary layer. Heat transfer coefficients correlate with sufficient accuracy with experimental data and dependencies published by other authors: J. M. Owen, L. A. Dorfman, I. V. Shevchuk. The deviation of the results obtained from the dependence of the model with a convective component and with affinity-like profiles do not have statistically significant differences. The obtained results of the study and their comparison with the results of other authors showed that they are suitable for engineering calculations and analysis of the impact of local heat transfer coefficients on high-temperature units of a turbopump unit.
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Magnetic capacity in manganese sulfides with rare earth substitution Mn1-xRexS
Статья научная
Polycrystalline samples Mn1–xGdxS and Mn1–xYbxS with a concentration x = 0.2, near the concentration of ion flow through the fcc lattice, are studied in order to determine fluctuations in the valence of the ytterbium ion on dielectric properties. Dielectric constant and dielectric losses were determined from measurements of capacitance and loss tangent in the frequency range 102–106 Hz at temperatures of 80– 500 K without a magnetic field and in a magnetic field. The magnetic capacity and dielectric losses in the magnetic field of the sample were determined from the relative change in the real and imaginary parts of the dielectric constant of the sample in a magnetic field H = 12 kOe applied parallel to the capacitor plates. A temperature range with a sharp increase in dielectric constant and with a maximum dielectric loss has been discovered, which shifts with increasing frequency and magnetic field. An increase in dielectric constant and dielectric losses in a magnetic field above 170 K was found in Mn1-xYbxS. The increase in dielectric losses is explained by an increase in relaxation time, as a result of local deformations near ytterbium ions during valence fluctuations. The mechanism for reducing reactance in a magnetic field in Mn1–xYbxS at low frequencies due to capacitance, and at high frequencies due to inductance, has been determined. In the Mn0.8Gd0.2S compound, the imaginary part of the dielectric constant has two maxima. The low-temperature maximum shifts in a magnetic field towards high temperatures and is described in the model of localized electrons with freezing of dipole moments. Dielectric losses decrease in a magnetic field. The magnetic capacity decreases by an order of magnitude in Mn0.8Gd0.2S compared to Mn0.8Yb0.2S. The dielectric constant in both compounds is described in the Debye model with the activation dependence of the relaxation time on temperature, where the activation energies differ for ytterbium and gadolinium ions.
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Magnetic characteristics of iron nanoclusters
Статья научная
The study of the nanocrystalline state, which significantly changes most of the physical characteristics of sub-stances, is very relevant. Of great practical interest are the works devoted to the study of the magnetic character-istics of nanocrystals of ferromagnetic substances. It has already been shown that the size of iron nanocrystals significantly affects the magnitude of their magnetization. Nevertheless, an adequate model of the structure of nanocrystalline formations consisting of a different number of iron atoms, which allows us to describe the exper-imentally detected changes in the magnetic characteristics, has not yet been presented. In this paper, we analyze nanocrystalline iron clusters that are different in configuration and number of their constituent atoms. Spatial models of clusters are constructed using a three-dimensional modeling program, and the coordinates of individual atoms in the cluster are determined. The proposed structures of nanocrystals are based on tetrahedrally close-packed cluster assemblies of iron atoms. The electron state density spectra were con-structed for the proposed clusters. For this purpose, the theory of the electron density functional was used, the calculation was carried out by the method of scattered waves in accordance with the band theory of crystals. It is shown that the appearance of magnetization in tetrahedral densely packed cluster formations is associat-ed with the excited electronic states of the atoms located on the surface of the nanocluster. Excited atoms have an increased electron density, that is, electrons are able to transition to states with higher energy, approaching the Fermi energy. In this case, the Stoner criterion necessary for the occurrence of magnetization is fulfilled. The con-figurations of electrons with spin up and down differ, which is why uncompensated magnetic moments appear. It is confirmed that the proposed models of iron nanoclusters satisfactorily correspond to the known experimental data.
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Magnetic impedance in nonstichiometric manganese sulfide
Статья научная
The role of defects on the dynamic characteristics of manganese sulfide is studied by impedance spectroscopy in the frequency range 102–106 Hz and temperatures 80–500 K. Nonstoichiometry plays an important role in the formation of new transport and magnetic properties, as it leads to electrically inhomogeneous states. The phase composition and crystal structure of nonstoichiometric manganese sulfide were studied on a DRON-3 X-ray unit using CuKα – radiation at room temperature. According to X-ray diffraction analysis, the synthesized compound is single-phase and has a NaCl-type cubic lattice. From the frequency dependences of the impedance components measured in the absence of a field and in a magnetic field, the relaxation time of the current carriers in the Debye model is found. A sharp decrease in the relaxation time and its correlation with conductivity were found. The contribution to the impedance of the active and reactive parts of the impedance at frequencies below and above the relaxation time is established. The capacitance from the impedance hodograph in the equivalent circuit model is determined. In defective manganese sulfide, the temperature-dependent impedance has an activation character. The activation energy is determined in the range 250–500 K, which is attributed to the excitation energy of lattice polarons. The effect of a magnetic field on the dynamic characteristics of current carriers was studied as a result of a change in the impedance components in a magnetic field at fixed temperatures. The impedance increases in a magnetic field and reaches a maximum in the temperature range of charge ordering of vacancies. An increase in the impedance in a magnetic field is explained by a decrease in the diagonal component of the permittivity in a magnetic field in an electrically inhomogeneous medium. The experimental data are explained in the Debye model.
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Статья научная
Bismuth pyrostannate Bi2Sn2O7 is a diamagnet and belongs to the structural type of the A2B2O7 pyro-chlore class. In this class of compounds, in the presence of magnetic ions, very interesting magnetic proper-ties appear. Chromium- and iron-substituted bismuth pyrostannates Bi2(Sn0.9Me0.1)2O7, Me = Cr, and Fe were synthesized by solid-phase synthesis. X-ray diffraction analysis showed that the samples correspond to the Pc monoclinic cell of the Bi2Sn2O7 α-phase at room temperature. The magnetic properties up to 1100 K in magnetic fields up to 0.86 T and the electric polarization at frequencies of 10, 3, and 1 mHz in the tem-perature range 80–550 K have been studied. The effect of heterogeneous substitution by Cr3+ and Fe3+ ions on the magnetic properties and electric polarization of bismuth pyrostannate is investigated. An analysis of the experimental data revealed the dependence of the magnetic properties on the degree of filling of the elec-tron shells of chromium and iron ions. The Bi2(Sn0.9Cr0.1)2O7 compound exhibits ferromagnetic properties, while Bi2(Sn0.9Fe0.1)2O7 exhibits antiferromagnetic properties. In chromium-substituted bismuth pyrostan-nate during the α→β transition, the paramagnetic Curie temperature increases by a factor of 3. The temper-ature dependence of the inverse magnetic susceptibility is characterized by hysteresis in the temperature range of 400–900 K. The reverse magnetic susceptibility of Bi2(Sn0.9Fe0.1)2O7 in the entire temperature range is satisfactorily described by the Curie-Weiss law. Studies of the magnetic properties have established that the Fe3+ ions are in a high-spin state. The polarization hysteresis in Bi2(Sn0.9Cr0.1)2O7 is found, which shifts along the polarization axis and depends on temperature. Bi2(Sn1-xFex)2O7, x=0.1 is characterized by a linear field dependence. With an increase in the concentration of iron ions, a hysteresis arises in the field dependence of the electric polarization. The hysteresis of polarization in Bi2(Sn0.9Cr0.1)2O7 which depends on temperature was found. The nonlinear field dependence of the polarization in Bi2(Sn0.8Fe0.2)2O7 can be ex-plained by the interaction of the dipole and migration polarizations and the presence of oxygen vacancies. For the Bi2(Sn0.9Cr0.1)2O7 compound, a transition to the dipole glass state was found. In the β-phase of Bi2(Sn0.8Fe0.2)2O7 above T = 400 K, no polarization hysteresis is observed and the electron-relaxation polar-ization predominates. The mechanism of the occurrence of electronic polarization is explained with the ap-pearance of anionic vacancies upon heterogeneous substitution of tin ions.
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Magnetic properties of Mn1-xGdxSe sol-id solutions
Статья научная
Potential materials for spintronics operating under extreme conditions based on manganese selenides substituted with gadolinium are investigated. The technology of synthesis of solid solutions based on solid-phase reactions using MnSe and GdSe compounds is presented. As a result, Mn1-xGdxSe solid solutions with concentrations x = 0.05; 0.1; 0.15 and 0.5 were synthesized. The synthesis was carried out under vac-uum conditions of 10–2 Pa. The products of the primary synthesis were subjected to thorough grinding into powders, from which tablets were made under pressure for homogenizing annealing at 1370 K. After two hours of exposure, the synthesis products were tempered in cold water. At the final stage, homogeneous strong ingots of greyish-silver color were obtained. X-ray phase analysis of synthesized solid solutions of the Mn1-xGdxSe system was performed in Cu-K radiation in the point-by-point measurement mode with a scanning step along the angle Δ2θ = 0,03 degree; the time of information collection at the reference point Δτ =3 seconds. The spatial symmetry group and the parameter of the elementary crystal cell of solid solu-tions of the Mn1–xGdxSe system from X-ray diffraction analysis are determined. The dependence of the pa-rameter value of the crystal lattice of solid solutions on the concentration of gadolinium ions is found. The specific magnetization was measured by the ponderomotor method in a magnetic field with an induction of B = 0.86 Tesla and the magnetic susceptibility of the samples was determined in the temperature range of 80 ≤ T ≤ 950 K. The cycles carried out in the heating - cooling mode did not detect a change in properties. The Neel temperatures and the paramagnetic Curie temperature are determined from the Curie – Weiss law depending on the concentration of a rare earth element. A decrease in the temperature of the magnetic phase transition is established.
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Magnetoimpedance in thulium manganese chalcogenide
Статья научная
Control of transport characteristics under the influence of a magnetic field is promising from the point of view of creating magnetic field sensors resistant to radiation. The impedance and its components in thulium manganese chalcogenide in the frequency range of 102–106 Hz are studied. The temperature range with a prevailing contribution of the reactive and active parts of the impedance is found. The impedance components are described in the Debye model. When manganese is replaced by thulium ions, the frequencies of the maxima of the imaginary component of the impedance shift toward high frequencies in manganese selenide by two orders of magnitude. With an increase in the concentration of substitution by thulium ions in selenides, two relaxation times are found, compared with sulfides. The activation nature of the relaxation time, the activation energy from the concentration of thulium ions are found. An increase in impedance in a magnetic field in the region of low concentrations and a change in the sign of the impedance with temperature for high concentrations are established. Magnetoimpedance in chalcogenides passes through a maximum when heating the samples. The increase in impedance in a magnetic field is due to a change in the diagonal component of the permittivity in a magnetic field, which is proportional to the conductivity. A positive value of magnetoimpedance is described in the model of an electrically inhomogeneous medium. From the impedance, information can be obtained about the electrical inhomogeneity of the material.
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Managing a group of objects as a task of system analysis
Статья научная
In this paper, we consider the general statement of the problem of identification and management of a group of objects. A group refers to several objects combined for the manufacture of a product. The main feature is that when managing such systems, it is necessary to change the setting actions for each object. This is due to the fact that today the technological regulations in many cases are wider than they should be for good operating. This is a consequence of the fact that the current production culture (this, in particular, has been shown by the experience of processing data from the technological process for the production of transis-tors at Svetlana) is rather low, which leads to some organizational problems. It is clear that it is necessary to have certain models of objects that naturally differ from each other and can be considered under conditions of both parametric and nonparametric uncertainty. Moreover, there may be cases when an object is considered simultaneously under conditions of both parametric and nonparametric uncertainty over various channels. Now, regarding the delay, due to the fact that the measurement of some variables is carried out in a significantly long-er time interval than the object constant, it is necessary to distinguish the time of measuring technological vari-ables and, in fact, the delay typical to the process itself, taking into account the difference between the channels. This leads to the fact that dynamic processes are essentially forced to be considered as inertialess with delay. Another significant feature is that the components of the output variables are stochastically dependent in ad-vance in an unknown manner. The use of correlation or dispersion relations in this case does not lead to success. A special analysis of T-processes and the ability to simulate such processes are required. In particular, this is one of the tasks of this article. It contains: T-processes, T-models and the corresponding heterogeneous control algorithms. The process of hydrodeparaffinization of diesel fuel is considered according to available data, which can be said a priori that they are incomplete, that is they do not reflect the complex behavior of the pro-cess. From here it follows that these data require replenishment, which today is not carried out for various rea-sons. Thus, the process of hydrodewaxing can be taken to the T-process. Modeling a multidimensional system based on real data has shown that in this problem the presetting effect for different objects should be different. The exception is only the setting actions for the entire complex or group of objects. Modeling was carried out on the basis of T-models considered in the article. It has already been not-ed that these models should not be taken as complete, giving an idea of reality. They will be subject to algorith-mic refinement during further research. The decision is made by the researcher. At this stage that an assessment is given that, under the circumstances, the resulting models and control algorithms can be adopted for use in a production environment. An attempt to use the existing theory of identification and control for the process of hydrodewaxing will inevitably lead to a significant degradation and increase in the cost of a computer system for operating the quality of this process.
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Статья научная
Operational characteristics of contacting elements of cars and mechanisms are by far defined by a layer quality indicators at the surfaces of contact. One of the ways of increasing details durability, including missile and space equipment details, is the superficial plastic deformation (SPD). In the article aspects of dynamic ways of hardening from the position of the wave theory of blow are considered. The construction of a shock stand on the basis of a linear electrodynamic drive with a size of 60 mm, operating in a shock-pulse mode, as well as a well-known mathematical model of the workflow – the movement of the armature with the tool at the moment of striking the surface. This model does not fully describe the operation process since the mass of the striker taken into account equaled 1 kg, which does not characterize the process of the impact tool, the purpose of which is the object deformation (for example, work hardening with the aim of surface material sealing or breakdown of the hole in it, or applying license plates markers). The mathematical model that describes the movement of the armature with the tool, taking into account the elastic deformation of the hardened surface was obtained. In the course of the performed calculation, the magnitude of the elastic deformation of the hardened surface was calculated from the dynamic component of the force impulse applied to it through the indenter (the tip of the impact tool). The layout of the shock stand with the equipment used, are offered. Experiments on the signal recording with various arrangements of piezoelectric transducers on the anvil – the hardened surface (diagrams of the sensors location are given) were carried out.
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Статья научная
One of the main characteristics of computer appliances for processing real-time information is reliability. The reliability of software is understood as the property of this software to perform specified functions, maintaining its characteristics within the established limits under certain operating conditions. Software reliability is determined by its reliability and recoverability. Reliability of software is a property to maintain its performance when using it for processing information in the information system. The reliability of the software is estimated by the probability of its operation without failures under certain environmental conditions during a given observation period. The development of real-time systems requires a large amount of resources for design and testing. One of the solutions to this problem is mathematical modeling of computer appliances. This allows more flexible design of real-time systems with the specified reliability, taking into account the limitations on price and development time, and also opens the possibility of more flexible optimization of computer appliances for real-time control systems. To develop a mathematical model of the reliability of computer appliance for real-time systems, it is necessary to take into account the provision of a given level of reliability, with reasonable development costs. There are many methods for improving software reliability, but the most promising and effective methods are redundancy, which is achieved using N-version programming. To increase the reliability of the hardware of the computer appliance, it is also necessary to use redundancy and redundancy, which includes multiprocessor and provision of different buses and independent RAM. This paper discusses existing approaches to improving the reliability of hardware and software, proposes a model of reliability of a computer appliance, which is understood as the product of the probability of failure-free operation of hardware and the probability of error-free operation of software. In addition, new formulas are proposed for the steady state probabilities of the hardware states of a multiprocessor computer appliance with heterogeneous processors, which give the same result as the existing ones, but require fewer computations. The paper concludes with a question about the possibility of optimizing the reliability of computer appliances based on the developed model, and indicates optimization methods that can be used to solve this problem.
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Статья научная
A mirror geometry control system for the Millimetron Observatory is being created to work as part of the on-board complex of scientific equipment. The system is designed to monitor the quality of the space telescope’s mirror system and use the data received as feedback signals for pre-setting and tuning the telescope’s optical system in outer space. The goal of the system is estimation of the multidimensional vector of unknown parameters of the telescope’s mirror system by indirect measurements obtained as a result of the measurement of the telescope by 3D scanning. A mathematical model has been created, numerically describing the process of pre-measurement of the mirror system of the Millimetron Observatory using optical control marks on the surface of the mirror system. The linear mathematical model allows to link the actual indirect measurements of the mirror system with the unknown biases of its parameters, determining the shape of the telescope. A formula has been developed for the optimal reverse problem solver in the process of pre-measurement of the mirror system. The method of measuring the components of the telescope as part of its pre-setting is described. The measurement of control marks is based on a onboard 3D scanner embedded in the design of the mirror system control system. The error analysis was carried out using the optimal solver, and a covariance matrix was obtained for the error vector of estimated parameter.
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Статья научная
In the conditions of continuous financing of the programs of the Ministry of defense of the Russian Federation, the question of finding the most effective ways to modernize weapons and military (special) equipment, the developments in which are maximum and the processes of their improvement can take no more than a few years, is particularly acute. Such products, in particular, include aviation artillery weapons (AAO), the prospects for the use of which remain for the entire period of the army's existence with conventional weapons. The main factor influencing the quality of the AAO functioning is considered to be the thermophysical loading of a small-caliber artillery barrel (hereinafter referred to as the barrel) during firing. The problem of increasing the accuracy of determining the temperature field of the barrel is again updated by tightening the conditions for striking targets. Issues closely related to the intensification of AAO application regimes have come to the fore. These are issues of heating, cooling, thermal strength, wear, barrel survivability, issues of safety and firing efficiency. Despite the methodological evidence of analytical and numerical approaches to formalizing heat transfer in the wellbore, their practical implementation is rather complicated. The physical and mathematical meaning of this reason is as follows: possible instability of solutions; manifestation of oscillations in areas of large gradients; simultaneous presence in the solution regions of supersonic, sonic and subsonic zones; the existence of laminar, turbulent flows and other non-linear formations; non-triviality of setting boundary conditions; the presence of thermal resistance of surfaces, etc. However, the practical needs of ensuring safety and increasing the efficiency of fire operation of AAO dictate the need to obtain a close approximation of the problem under consideration to its possibly existing exact analytical solution. The aim of the work is to improve the mathematical apparatus that simulates the temperature field of the shaft based on a combination of heat transfer methods and mathematical physics. By verifying the reliability of the developed mathematical model (hereinafter referred to as the model, if from the context of the presentation of the material it is clear that we are talking about the proposed tools), the facts of the absence of methodological errors in the formation of the constituent blocks of the model and the increase in the accuracy of determining the thermal loading of the wellbore by 9.4 % were established. Based on the accents of the stated problem, the directions for improving the model are argued.
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Mathematical modeling of autocompensation devices
Статья научная
The article studies the order of developing and describing mathematical models of automatic compensation devices of all-round radar stations. The development of algorithms for spatial processing of signals in radar systems with phased antenna arrays is an important stage in the design of radar stations. This article considers the procedure to create mathematical models of automatic compensation devices that differ in implementation methods, namely: the number of compensation channels, the position of the main and compensation (additional) channels of the radar station (stationary or dynamic), the amplitude-phase distribution of the main and additional antennas, the representation phased antenna array, algorithms for finding the weight vector. The method of computational experiment verifies the adequacy of the operation of the models and the results are comparable with the implemented automatic compensation devices in radar stations. Presented in the form of graphs of the signal at the output of the automatic compensation device as well as the passage of the matched filter, the results of the computational experiment show effectiveness of the algorithm to calculate the weight vector; they permit to visually, quickly and economically compare the efficiency of the automatic compensation devices, depending on the method of their implementation. The article discusses the algorithm for the direct formation of the weight vector and the algorithm for the formation of the weight vector through the inverse correlation whitening matrix. Mathematical models of automatic compensation devices and the results of a computational experiment can be used to train future specialists who develop and operate radar stations.
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Mathematical modeling of the flat ingot casting process for solving automation problems
Статья научная
Aluminum alloys are widely used in the production of aircraft due to their strength, lightness, corrosion resistance, and necessary electrical conductivity. At the same time, aluminum ingots used in further processing of the space industry must be of high quality. Technological problems and defects arise when temperature, speed, and other technological parameters of casting are not observed, or when modes change. At the same time, foundry processes are partially automated; the human factor significantly affects product quality and work safety. Therefore, automation of these complex processes using mathematical models to predict casting parameters is an urgent task. The goal of the work is to create mathematical models available for use in automated process control systems (APCS), as well as for the development of a digital twin. The work presents simplified formulas for modeling the temperature distribution of an aluminum ingot during the casting process, cooling the metal when moving along a metal path, and test calculations of the temperature distribution inside the ingot when the ingot reaches a fixed length. The results of this work can be used to improve the efficiency and accuracy of controlling the process of casting aluminum ingots, to eliminate emergency situations.
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Статья научная
In this scientific work, a method of controlling high-frequency products from polymeric composite materials is considered. The authors of the work present the rationale for choosing a method of high-frequency diagnostics as the most suitable for non-destructive testing of products from polymeric materials of machine-building and rocket-space purposes. In the presented article, the primary task of creating and studying a mathematical model of the effect of highfrequency radiation on a polymer product, including those with a “metallic inclusion” defect, has been stated and solved. In addition, the work presents the calculations of diagnostic parameters using the mathematical model developed during the study. The calculation of the dynamics of heating the product and the temperature distribution during the control process is presented. The results of the calculation of specific power are described, the dependence of the instantaneous power consumption on the warm-up time is found. In the study based on a mathematical model, the Aleo- Diagnost software package was developed and registered, which is directly intended to ensure the functioning of the diagnostic devices and the investigation of the monitoring process. In addition, the developed complex allows solving a number of such practical problems as the calculation of the operating voltage depending on the geometrical parameters of the product and the determination of the value of energy consumed for monitoring the product for a specified period of time. This stage was necessary, as the consumed energy is the main output parameter of the diagnosis. In addition, the value of energy consumed is taken as the basis for the organization of the process of non-destructive testing in the automated mode. The solution of the tasks in this work has significantly reduced the cost of preparation of diagnostic operations, as well as improve the quality of control of products on an industrial scale at the stages of manufacture, operation and during repair work. The article also presents practical results, conclusions.
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Measurement of temperature distribution using a three-wire system of sensors based on thermistors
Статья научная
Improving the reliability and increasing the avionics resource is associated with possibility of continuous control of temperature fields of printed circuit boards. This problem can be solved only with the use of a large number of temperature sensors. It raises the problem of connecting the measuring elements and recording equipment. Several methods with their own advantages and disadvantages are proposed. One of the implemented and patented methods is using a set of resistive diode sensors installed in series on a threewire line. The temperature sensors are pairs of counter - connected diodes with a sequential survey when applying sawtooth voltage. The system is simple and easy to implement, but its main drawback is the method of determining the temperature by measuring the amplitude of the total reverse currents of diode pairs. It determines the large measurement errors, especially in the temperature range less than 20°C. The article deals with a similar design of a three-wire circuit, but with a fundamentally different approach to temperature measurement. The temperature sensor here is not diode pairs, but thermistors with a well-known dependence of resistance on temperature and high accuracy, and diode pairs record only the moment of coincidence of the sawtooth voltage with the voltage on the thermistors. This approach allows using mathematical methods of signal processing to accurately determine the voltage drop on the thermistor, and this ensures the accuracy of the resistance/temperature and the expansion of the temperature range. Given the fact that thermistors are increasingly used to measure temperature, simplifying their inclusion in a large number will allow to register the temperature field of electronic units, which is extremely important for spacecraft. The proposed version of a three-wire circuit for connecting temperature sensors at several points was tested experimentally, including at negative temperatures.
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Статья научная
Based on the previously compiled physical and mathematical model of the vortex ejector workflow, its solution was made. The solution of this model made it possible to compile two calculation methods: a method for calculating the optimal geometry of a vortex ejector for given thermodynamic characteristics and a method for calculating the thermodynamic characteristics of a vortex ejector with known geometric dimensions [1; 2]. Vortex ejectors are used in many areas of aerospace engineering. The compiled development of a method for calculating the thermodynamic characteristics of a vortex ejector with known geometric dimensions will make it possible to use vortex ejectors more widely in the aerospace industry. The calculation method is based on the concepts of tangential stresses arising in a viscous medium when two flows moving at different speeds interact. The mechanism of kinetic energy transfer from a high-energy gas to a low-energy one is shown.
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Статья научная
The construction of detailed accounting that allows to generate complex analytical reporting is an in-dispensable requirement of a modern financial system. For enterprises of the State Space Corporation “Roskosmos” with custom-made and small-scale production, operating in the conditions of Federal Law No. 275, characterized by a large amount of R&D and a high degree of uncertainty in the process of creat-ing products, this task is a system-forming one. The reporting should contain consistent data in any area of management and accounting at any given time. Along with this, system must provide the flexibility, reliabil-ity and performance inherent in transactional databases. To build information support that satisfies the specified conditions, it is required either to separate OLTP and OLAP data schemes, or to apply special-ized solutions based on the use of structures and techniques optimized for performing OLAP operations in traditional RDBMSs. This article considers the approach to form the multidimensional data in an automat-ed management system for economic tasks, as an effective alternative to complex and expensive BI solu-tions. Unlike many commercial systems, the ASU FEZ does not store redundant data (for example, opera-tional accounting registers in the 1C: Enterprise platform) required to build analytical accounting. The underlying data structures and methods of their processing allow for all types of accounting and have pow-erful tools for constructing analytical reporting. The article proposes algorithms for the operation of the system using the example of building simple OLAP cubes used in real tasks of automating financial and economic activities in ISS JSC for one of the Purchase subsystems. The formalization of these problems is carried out, the mathematical apparatus for constructing multidimensional data models based on infor-mation from a fixed set of normalized tables of a relational database is considered.The examples of SQL queries and outputs are provided. The advantages of using the system in operational management and accounting at the enterprise increasing its operational efficiency are summarized.
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