Статьи журнала - Сибирский аэрокосмический журнал
Все статьи: 3183
Approach to optimization of the magnetic circuit of a three-phase induction plant
Статья научная
The article describes an approach to optimization of the electromagnetic regimes of an induction metallurgical plant, designed to mix liquid aluminum under the influence of a running magnetic field. To improve the properties of the molten metal in the furnace, short pole linear magnetohydrodynamic machines with copper windings and a steel core are used. The open configuration of the magnetic circuit and the magnetic coupling between the windings of the inductor lead to asymmetry of the magnetic field. As a rule, a low-frequency transistor inverter is used in the power supply system of metallurgical machines intended to affect non-ferrous metals. Asymmetrical currents in the phases create specific modes of the frequency converter, close to emergency, and a two-phase, three-phase or multi-phase power supply system may become unbalanced. To calculate the integral magnetic fluxes in the toothed zone of an induction installation, it is convenient to apply a multiphase nonlinear model of a magnetic circuit. As a result of the iterative calculation, vector magnetic flux diagrams are obtained and the tractive forces in the melt are estimated. The best conditions for the impact on the melt are obtained with a given objective function when searching for options during optimization of the magnetizing forces of the windings.
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Assessment of spacecraft solar array reliability during ground experimental development test
Статья научная
The increase of available power and the lifetime up to 15 years for modern telecommunications satellites significantly actualize the challenge of improving large-sized foldable solar arrays (LF SA) reliability. The reliability of any equipment to be implemented onboard of a spacecraft depends mainly on the quality of their ground experimental test development (GTD). To ensure high quality GTD it is important to accept the correct concept of SA reliability validation, taking into account the specifics of the SA design and the real capabilities of the test facilities. The paper describes constituent parts of the concept allowing validating the large-sized foldable solar arrays reliability at the phase of ground experimental test development. There has been obtained the system of differential equations which describes SA deployment using the off-loading system and, as a result, solving of the differential equations system to estimate errors introduced to the SA elements motion dynamics by the test equipment is given. “Yamal-401” spacecraft SA mechanism reliability has been calculated. The stresses impacting SA mechanism elements during deployment under zero gravity, used during calculation and design of “Yamal-401” spacecraft SA have been defined. The developed methodologies of numerical tests have allowed validating the reliability of all large-scale SA structure elements, under all extreme cases, with regard to the available test facilities. This approach allows performing experimental test development of any large-size SA under development for new generation spacecrafts using existing experimental test facilities and equipment. The results of the research have been used by JSC “Information satellite systems named after academician M. F. Reshetnev” at the phase of ground experimental test of large foldable SA structures for “Express-AM5”, “Yamal-401” spacecrafts and other spacecraft types.
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Статья научная
The structure of the invariant echo-jack of the second order without a protective time interval is synthesized. Control elements of such echo-jack are given. The calculation of the basic technical characteristics is presented.
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Automated weight compensation system for ground-based tryout of space vehicle solar panels
Статья научная
In the process of ground-based tryout of solar panels placed aboard the spacecraft there appears the problem of gravity effect compensation. The energy of deployment mechanism is extremely limited, the weight and strength of the structure being calculated for weightlessness conditions. Therefore, under the force of gravity, the power of deployment drives may not be enough to complete the tryout, and the structure itself may be destroyed. Taking into account these difficulties, specialized stands the main part of which is the so-called weight compensation system are designed and created to conduct ground-based pilot tryout. Active weight compensation systems are most effective in this case. In the stands with active weight compensation systems all forces generated by the stand and movements of the stand parts occur through controlled drives. By introducing various sensors into the weight compensation system and by the use of their signals for generation of controlling actions in the control system it becomes possible to significantly increase the level of gravity effect compensation, as well as to minimize the influence of the stand parts inertia. The paper presents the results of the designing, building and testing of the automated active weight compensation system for solar panels. The system provides weight compensation when conducting ground-based experimental tryout of any objects (solar panels, rods, multi-tier spokes, etc.) having a long and transformable in one direction form for distances of the order of 20 m (longitudinal direction). This system also provides movement of the pieces of a tested object in the transverse direction and in height for distances of up to 5 m. The results of departmental tests showed that the weight compensation system with specified parameters described in this paper allows for ground-based tryout of the deployment of solar panels of all constructions, both currently existing and being developed for the future.
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Automatic linear differential equation identification in analytical form
Статья научная
In this paper we suggest a reduction of linear dynamics identification problem to the global optimization task. The current approach allows automatic determining the structure and parameters of a linear differential equation via the usage of the modified hybrid evolutionary algorithm for extremum seeking. The a priori information algorithm needed is only the dynamic system initial point or an estimation of the initial point and the sample of measurements: system output and, if there is one, system input.
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Background restoration in frame areas with small-size objects in video sequences
Статья научная
A general concept of removal of artificially overlaid images, natural damages of video images and other small-size objects is presented. The classification of artificially overlaid images is developed. The algorithms of feature points detection and feature points tracking used in video sequence restoration are considered.
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Balancing small engines-flywheels
Статья научная
When you create a small spacecraft there is the problem of redressing the imbalance of the rotor-flywheel of the small engine flywheel with the selection of weights, while the mechanical contact method leads to elastic deformation in the supports of rotation, which has a negative impact on their work especially at high speeds of rotation of the flywheel. From this perspective, there is a need to study other ways of balancing of rotors, flywheels, namely contactless bal- ancing of rotor of flywheels with the help of concentrated energy fluxes of laser and electron-beam evaporation of the metal. The technology of balancing with an electron beam has a number of advantages over the laser technology of bal- ancing for the realization of balancing of rotors of flywheels. For example, it is possible to implement the process of redressing of imbalance in the vacuum that brings the balancing conditions to real operating conditions. Also the reflectance of energy in the processing of electron beam is much lower than during laser processing, which demon- strates the efficiency of the process. The dependences of the intensity of evaporation from the settings of the laser and electron beam are defined. Contactless balancing of rotors of flywheels with the help of concentrated energy fluxes evaporation of metal is cur- rently possible, but it is necessary to have special equipment with the required capacity of operation.
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Buckling of orthotropic plates with the two free edges loaded for the pure in-plane bending moment
Статья научная
In this paper we have solved the buckling problem of orthotropic plates with two free and two simply-supported edges loaded for the pure in-plane bending moment. We have used the finite difference method to solve the problem.
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Cad system for perspective power supply network development task solution
Статья научная
The process of urban power supply network development is connected with need calculation and accounting a large number of parameters, possible development ways and complexity of their assessment. These circumstances require the introduction of new technologies for solving specified task. Declaration of author’s developed computer-aided design system (CAD system) ELNET for the task solution automation of perspective urban power supply network development is presented in article. Description of models, methods and algorithms based in the CAD system are given. CAD allows to create, correct, calculate parameters, look through and print models of urban power supply networks. ELNET consists of six connected modules: graphic module, control module (dispatcher), input/output module, solutions module, calculations module, reference data base. System possesses the friendly graphical interface allowing ease using. In CAD ELNET mathematical basis puts designed by author mathematical model of urban power supply network presentation as directed weighted graph and two methods of solving urban power supply network development task: the reduction method to the set of enclosed global minimization tasks and decomposition method. Both methods suggest dividing a given task into three subtasks of smaller dimension: 1. Subtask of definition the number and locations of new substations. 2. Subtask of definition the connection way of new consumers to network. 3. Subtask of definition the optimum connection way of new substations to the existing network. The optimization algorithms of subtasks solution are realized by the author. For solving subtask 1 three algorithms are designed and realized: algorithm based on the k-averages method; algorithm realizing the method of dividing clustering; heuristic algorithm. For solving subtask 3 three algorithms are also offered: heuristic algorithm of the reduced enumeration; genetic algorithm; algorithm based on constructing Voronoi diagrams. To solve subtask 3 the genetic algorithm is applied. Technical solutions represented in the article allow reducing time of design and increasing the quality of design decisions.
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Статья научная
The deformation of plates is reduced to the generalized problem of eigenvalues based on the stability criterion, which establishes equilibrium in the mechanical system. A method for calculating stability for thin plates under inertia loads exerting force on the basal plane is proposed. Having a differential formulation of the problem, the matrices are formed. The first is a stiffness matrix: it is based on Marie-Sophie Germain’s biharmonic equation. The second matrix represents the change of internal stresses or internal forces in the plate. The stiffness matrix is always symmetric and positive definite for the fixed plate. The matrix of the internal forces in the approximation of derivatives of functions under central differences, from the action of inertial forces can be asymmetric with respect to the main diagonal, can also degenerate and rows of this matrix is the feature of inertia loads. The finite difference method allows us to form a system of large dimensional equations. However, difficulties may arise at the free edges and corners of the plate, which complicates the calculation procedure. Therefore, a transition from the differential formulation of the problem to an integral formulation discretization with variational-difference method is performed. In this case a second row of nodes is not formed during the formation of the stiffness matrix at the free edge. The matrix of the internal forces is always symmetric; it can be ill-conditioned, however, this factor does not affect the problem of determining eigenvalues. Scientific literature provides many theoretical studies and solutions to practical tasks of calculating the stability of structures, including the calculation of longitudinal-transverse bending of thin plates. However, this is a task that has positively certain operators. We have conducted a research of the application of the variational-difference method for calculating the stability of structures. The differential formulation of the boundary value problem is transformed into a variational formulation; the stability criterion is solved; the issue of approximating differential operators for discrete problems with a finite number of variables is addressed in the paper. The paper also describes a developed set of algorithms for the Maple mathematical system and a compilation of calculating programs. Examples of the calculation are considered. We have studied a plate that is rigidly secured at one side while the other three sides are left unfixed. Values of the critical accelerations have been obtained. Problems are assigned to the generalized problem of eigenvalues in which the acceleration parameter, such as the parameter of load, is the only unknown property. Paper objective: the development of a method for calculating inertia loads on plates.
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Calculation method for automatic secondary power sources
Статья научная
The article describes methods for calculating the parameters of secondary power sources (SPS): rectifying devices and voltage impulse stabilizers. Algorithms for calculating parameters of SPS power circuits have been developed.
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Статья научная
A simple method for calculating the parameters of a forest fire is offered. The method is based on the representation of a fire as a mobile set on the surface of the Earth. The information base for the proposed methodology is the data of space monitoring of forest fires.
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Статья научная
Modern technologies make it possible to construct electronic devices that combine small sizes and high energy con- sumption, which requires the optimization of thermal modes. A promising direction to improve cooling intensity of the heat-loaded element (HLE) and precision of temperature control is applying thermoelectric modules (TEMs), which endow the heat release system with a cooling function, i. e., allow to reach temperatures of the HLE below ambient temperature. In the present paper, the processes of heat transfer in thermoelectric system of cooling and temperature control (TESCTC) are comprehensively considered. The temperature field in the capacity of heat-distributing plate (HDP), and influence of the heat flux inhomogeneity on the HLE temperature increase have been defined. The results of operating modes calculations, taking into account the heat-power release of HLE, performance of TEM, parameters of HDP and cooler, and magnitude of thermal resistance of thermal contacts have been presented. The calculation method allows to determine the temperature of HLE and to optimize TESCTC modes to achieve maximum cooling effi- ciency and lower energy consumption. It has been found that the optimal power supply current of TEM, corresponding to the modes with the maximum efficiency of cooling, depends on the thermal resistance of the heat sink system and the power of the heat load.
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Статья научная
The thermal control system (TCS) is one of the most important systems, which largely determines the design of the spacecraft. At the present stage of development of methods and tools for spacecraft design, a promising direction is the creation of thermal mathematical models of the TCS, calculation algorithms, which allow to create effective design solutions at various design stages. The purpose of this work is to bring the system of equations of heat balances of the liquid circuit (LC) of TCS to a form that allows programmatic numerical integration in the solution search algorithm along the length of the middle line of the heat and mass exchange fluid circuit taking into account certain complex thermal resistances. In fact, this means that the terms of the temperature of the contour and the linear coordinate, the integration variable, should remain as variables in the equation record, everything else should be numerically determined from the properties of the real object. For the boundary conditions of the LC TCS of the spacecraft, the coefficients of complex heat transfer were calculated taking into account the actual topology of the circuit and the thermal properties of the coolant. Using these values, the system of thermal balances of the spacecraft of the spacecraft on the characteristic surfaces of constant temperatures was reduced to a form that allows a numerical solution: the number of equations corresponds to the number of detected temperatures along the north and south panels and is closed through the temperature of the liquid circuit refrigerant. The resulting system of equations allows us to investigate the thermal state of nonhermetic formation spacecraft at the stage of preliminary design with varying operational and design parameters in order to determine the area of efficiency and the area of optimal operation under certain performance criteria.
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Статья научная
The present paper describes an FPGA design of a camera-to-touchscreen demonstrator that has been prepared using Xilinx Vivado 2015.2 and SDK 2015.2 tools. The demonstrator consists of MicroZed 7020 Carrier Board, Avnet 7-inch Zed Touch Display and Avnet Toshiba Industrial 1080P60 Camera Module. The camera transmits a full HD video signal at 60 frames per seconds to MicroZed 7020 board, which processes it and sends to the LCD display with active area of 800×480 pixels. As the display has smaller resolution, only a fragment of the whole video frame can be seen at once on the display, whereas the full image is stored in the memory. By touching the screen one can travel along the stored video frame and look through the whole image. The design can be used, for example, as a car rear view mirror monitor benefiting from touchscreen technologies
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The method of solving the boundary-value problems for hyperbolic system of the homogeneous quasilinear equations of two independent variables with the help of conservation laws is presented. This method is applied to basic boundary problems for the system of two-dimensional plasticity equations under Sent-Venan-Mises yield criterion, as well for the system under Coulomb's criterion.
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Combinatorial optimization in foundry production planning
Статья научная
The mathematical model of foundry production capacity planning is suggested in the paper. The model is produced in terms of pseudo-Boolean optimization theory. Different search optimization methods were used to solve the obtained problem.
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Company management system estimation on the basis of adaptive correlation to the environment
Статья научная
The method of the structure and indicators analysis of company business processes based on the calculation of simple correlation between historic series of expenses is offered.
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Comparative analysis of typical regulation algorithms and nonparametric dual control algorithm
Статья научная
The task of nonparametric dual control algorithm and standard regulation laws (P-, PI-, PID-regulators) at dy- namic objects with discrete-continuous nature of the technological process control is considered. It means that in itself, the dynamic process is continuous, however, the “input-output” variables of the process are controlled through discrete instants. In the case under study, the structure of the process model is partially parametrized. It means that equation order is determined from prior information, but at the same time functional dependency between “input-output” vari- ables of the process remains unknown. The methods of dynamic processes modeling and control based on nonparamet- ric algorithms are offered. The complexity of dynamic process modeling and control under condition of incomplete information is discussed. This level of prior information is characterised by the lack of model structure knowledge, but the information on object qualitative characteristics, for example, unambiguity, or ambiguity characteristics, linearity for dynamic processes or the nature of its nonlinearity is required. Methods of nonparametric statistics are applied to identification problem solving at this level of prior information. The problems of identification and control in the conditions of incomplete information are very relevant because many dynamic processes are not deeply studied and the presence of unknown distribution random noises causes more complexity in solving the identification and control tasks. The results of computing experiment which show the efficiency of nonparametric dual control algorithm in comparison with standard regulators are presented
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Статья научная
The competitiveness of higher educational institutions in the market of educational services of Krasnoyarsk region is considered in the article, the concept “the higher vocational training” is also given in the present research. The problem urgency is proved, the general approaches and conditions of research of competitiveness of higher educational institutions are shown, major factors for a competitiveness estimation are allocated.
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