Статьи журнала - Сибирский аэрокосмический журнал
Все статьи: 3183
Compound bending of an orthotropic plate
Статья научная
The problem of longitudinal-transverse deformation and strength of an orthotropic plate on the action of a local transverse force and stretching along the contour of the membrane forces is studied. The direction of laying the fiber of a unidirectional composite that provides the lowest level of stress and deflection is determined. In the zone of application of concentrated force in thin-walled structures, significant bending moments and shear forces occur, which are a source of stress concentration. To reduce stresses, the method of plate tension by membrane forces applied along the contour is chosen. The maximum possible order of membrane tension forces is selected, which provides conditions for the strength and rigidity of the solar panel plate structure, which has a hinge-fixed support along the contour. Pretensioning the plate web allows to reduce the stress by 50 times. The problem of compound bending of isotropic and anisotropic plates when applying transverse and selection of longitudinal loads, with restrictions on strength and stiffness, can be called a problem of rational design of the structure. The resulting equations and calculation program can be used in the design of plate structures, as well as in the educational process.
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Comprehensive method for multimodal data analysis based on optimization approach
Статья научная
In this work we propose a comprehensive method for solving multimodal data analysis problems. This method in- volves multimodal data fusion techniques, multi-objective approach to feature selection and neural network ensemble optimization, as well as convolutional neural networks trained with hybrid learning algorithm that includes consecutive use of the genetic optimization algorithm and the back-propagation algorithm. This method is aimed at using different available channels of information and fusing them at data-level and decision-level for achieving better classification accuracy of the target problem. We tested the proposed method on the emotion recognition problem. SAVEE (Surrey Audio-Visual Expressed Emotions) database was used as the raw input data, containing visual markers dataset, audio features dataset and the combined audio-visual dataset. During the experiments, the following variable parameters have been used: multi-objective optimization algorithm - SPEA (Strength Pareto Evolutionary Algorithm), NSGA-2 (Non-dominated Sorting Genetic Algorithm), VEGA (Vector Evaluated Genetic Algorithm), SelfCOMOGA (Self- configuring Co-evolutionary Multi-Objective Genetic Algorithm), classifier ensemble output fusion scheme - voting, averaging class probabilities, meta-classification, as well as resolution of the images used as input for the convolu- tional neural network. The highest emotion recognition accuracy achieved with the proposed method on visual markers data is 65.8 %, on audio features data - 52.3 %, on audio-visual data - 71 %. Overall, SelfCOMOGA algorithm and meta-classification fusion scheme proved to be the most effective algorithms used as part of the proposed comprehen- sive method. Using the combined audio-visual data allowed to improve the emotion recognition rate compared to using just visual or just audio data.
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Computerized test stand for investigation of strain waves in composite constructions
Статья научная
The paper presents a test stand for investigation of ramp loading of composite constructions such as beams and plates. This ramp loading was performed using a striker with a piezoelectric force transducer. The velocity of the striker is up to 40 mps. The registration of the measurements results is carried out using a computerized measurement system. The experimental results of contact shock force acquisition are stated with appropriate calculations of nonstationary bending and shearing strain waves in glass-fiber-reinforced plastic beams and plates.
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Conceptual model of the investment priorities estimation in infocommunications
Статья научная
We offer a new conceptual model for investment priorities estimation. It provides the analysis in a regional profile, industry profile and on a micro level. The model combines a number of economic-mathematical methods of modeling, including cluster and multivariate regression analyses. It is recommended to use theory and systematic tools of the real options concept for the priorities estimation on a micro level.
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Consideration of optimal control of strictily hierarchical manpower system
Статья научная
The paper describes the problem of finding an optimal control strategy for the manpower control system. The equilibrium condition for the strict hierarchical manpower system control is stated which enables development of optimal strategy algorithm for one state example. Based on the equilibrium condition, the novel approach to the determination of optimal control in such system is described. Optimal tracking algorithm is described by example, which is implemented in MathematicaTM. The tracking algorithm is able to find the optimal values of the transition coefficients, so that the system achieves the desired value in one step. For the case when the desired value is not achievable in one step due to the boundary conditions, additional two algorithms are considered which bring state values to the desired ones in several steps. Two variants of the algorithm are considered, when the desired value is lower or greater than the initial value.
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Construction of elasto-plastic boundaries using conservation laws
Статья научная
The solution of elasto-plastic problems is one of the most complicated and actual problems of solid mechanics. Traditionally, these problems are solved by the methods of complex analysis, calculus of variations or semi-inverse methods. Unfortunately, all these methods can be applied to a limited number of problems only. In this paper, a technique of conservation laws is used. This technique allows constructing analytical formulas to determine the elasto-plastic boundary for a wide class of problems. As a result, the elasto-plastic boundaries were constructed for twisted straight rods with cross sections limited by piecewise smooth contour, for flexible consoles with constant cross-sections, as well as for anti-plane problems. Computer programs for construction of elasto-plastic boundaries for twisted straight rods were written using obtained technique. In this work, the elasto-plastic boundary arising during the torsion of a straight beam of arbitrary cross section, which is limited by a piecewise smooth contour is constructed; and the elasto-plastic boundaries for the problems of a consol bending and anti-plane deformation are found. The plan of the paper is the following. In the first section the basic equations of elasticity and boundary problems are considered; in the second section the basic equations of the theory of ideal plasticity of von Mises are given; in the third section the conditions on the boundaries of the elastic and plastic domains are formulated. The fourth section is devoted to torsion of elastic prismatic rods; the fifth one describes elastic bending of bars; in the sixth section the plane problem of theory of elasticity is given. The seventh section covers an anti-plane problem of elasticity theory; in the eighth section, conservation laws for the equations of elasticity are constructed; in the ninth one, conservation laws of two-dimensional equations of plasticity are discussed. In the tenth section an elasto-plastic boundary of a twisted straight rod is found; in the eleventh one an elasto-plastic boundary in the bended console is given; and finally, in the twelfth section a method for the construction of elasto-plastic boundaries for large areas is described.
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Context-dependent grammar design for describing complex scenes with multi-level object motion
Статья научная
The problems of context-dependent grammars formation which describes structural information about patterns and pattern interaction in complex scenes are discussed in this article. The application of three-level grammar based on the task of an image sequences syntactic analysis (with extended contents of main and auxiliary dictionaries) and the task of scene syntactic analysis with multi-level object motion is suggested.
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Control and regulation equipment of electric power system for a prospective piloted transport system
Статья научная
The aim of this work is to consider solving complex of tasks focused on fulfilling the complicated tactical and tech- nical requirements for regulation and monitoring equipment (RME) of electric power supply system (EPS) for a prospective spacecraft. These requirements are imposed due to the need to ensure high reliability of the equipment during operation under the influence of external factors (vacuum, vibro-impact loads, radiation, absence of convective cool- ing), as well as to achieve high mass-dimensional parameters of the equipment and its high functionality The complexity of problem solving lies in the need to ensure conflicting requirements - high levels of energy density, weight and size characteristics, reliability and durability. These problems fully apply to the RME of the EPS for a prospective piloted transport system (PPTS) which design example shows ways of solving abovementioned problems. The most rational way of solving these contradictions is to increase the specific energy indicators of the main com- ponents of the RME devices - power converters, which can be achieved by using modern power electronic elements, using new materials and semi-finished products, for example, printed circuit boards with a metal heat sink, as well as increasing the layout density design. Determining solution is to select an optimal structure of the power converter, which provides the best efficiency. An additional way to reduce the mass-dimensional indicators of the RME is the use of a digital control method, the collection of telemetric information, and the receiving and processing of commands. At the same time, on the contrary, to ensure the specified reliability of the equipment, it is necessary to use excess reservation at the element level - for power components, and the principles of majority reservation at the functional block level - for control and telemetry schemes. Using the example of RME, developed by CJSC “Orbita”, the main EPS parameters of a new generation spacecraft are shown and most important power supply subsystems are considered in the article: the solar energy control subsys- tem and the power storage subsystem, ways to build them for meeting specified requirements, taking into account the proposed solutions. As a result of this work, the optimal structures of power converters - the current regulator of the solar battery and the current regulator of the battery - were selected, the basic principles of power components reservation ensuring the operability of the equipment in case of a single failure of any component without loss of performance and deterioration of RME parameters as a whole are shown. Block-modular construction method is used for optimal layout and high reliability of the RME, it ensures uniform heat removal from electronic components, which is especially important in vacuum conditions, minimum dimensions and mass optimization of the RME, as well as high mechanical strength of the structure. The implemented principles of building the RME for PPTS using this approach will allow to increase the active lifetime (ALT) and reliability of the spacecraft with a simultaneous decrease in mass and dimension parameters.
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Статья научная
To reduce life time testing period of lithium-ion accumulator (LIA) special dynamic stress test (DST) is widely used. Lithium-ion accumulator dynamic stress test requires automatic charge-discharge devices (CDD) which provides nec- essary DST technological parameters with required precision. Authors developed charge-discharge devices with load converters (CDD-LC), which allow to reproduce required charge-discharge modes of high-power LIA automatically. LIA cyclic charge-discharge with constant power pulses is the most difficult mode of DST. In this case, control sys- tem became nonlinear and time variant due to computation of signal power as multiply of LIA voltage and current. Authors studied mathematical model of electromagnetic processes of CDD-LC in LIA power stabilization mode, formulated requirements to power stabilization control loop quality parameters, synthesized correction devices provid- ing necessary control quality, studied CDD-LC control process absolute stability with Naumov-Tsypkin in LIA power stabilization and regulation modes.
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Статья научная
The aspects of objects' investments appeal are studied. The basic estimation methods of the real estate market are analyzed. A method of information system construction objects' cost estimation of investment is proposed.
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Criteria of airframe corrosive damage
Статья научная
From the analysis of tasks caused by necessity to mitigate and prevent effects of corrosion during scheduled service, the most important one is to define the boundary parameters of corrosion damage.
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Статья научная
Development trends of modern business services markets lead to the unification of the range, quality and cost of services. Under these conditions, the customer relationship management becomes the most important factor for a business services’ company competitive ability.
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Cинтез оптимальных по быстродействию систем высокого порядка
Статья научная
Исследованы возможности синтеза систем автоматического регулирования, описываемых системами дифференциальных уравнений третьего и четвертого порядка, оптимальных по быстродействию. Выполнен анализ существующих разработок для создания систем высокого порядка, оптимальных по быстродействию. Представлена простая методика синтеза, основанная на методе фазовых траекторий. Предлагаемая методика включает в себя все этапы создания оптимальной по быстродействию системы от исходного описания в виде дифференциального уравнения или передаточной функции до формирования корректирующего звена. Сложность создания системы высокого порядка, оптимальной по быстродействию, заключается в необходи- мости иметь для управления информацию о n – 1 производных, где n – порядок системы дифференциальных уравнений. Однако технически получить такую информацию практически невозможно. Предлагается способ создания устройства для получения необходимой информации при синтезе систем высокого порядка, опти- мальных по быстродействию
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Статья научная
Рассмотрены базовые аспекты синтеза и применения организационно-экономического механизма управления группировкой малых предприятий промышленности муниципального образования. В качестве полигона избран г. Улан-Уде.
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Definition of participants of the investment project
Статья научная
For success of any investment project its careful planning is necessary. For this purpose it is necessary to consider interests of all persons which can affect its execution and results. Such persons form a social network of the project, some aspects of definition of such network are described in the present article.
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Delimitation of the investment project
Статья научная
Project's scopes and works management is the important component of any investment plan. One of the ways of project's risks minimization involves more exact definition of those works which should be executed for the benefit of project completion and desirable cash flow obtainment.
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Deployment concept mechanical system of a radar antenna for space purposes
Статья научная
One of the basic requirements to deployable mechanical systems is observance of requirements on execution of the first eigenfrequency of structure. In case of transformed structure like solar array, when the structure consists of any panels series connected with joints, this requirement is supplied with high rigidity of a structure. At low rigidity (lower then require) inevitably engenders unnecessary effects on orientation and stabilization system of spacecraft on orbit. Other major aspect of designing of space engineering is decrease in final weight of a product. The most typical line of designing of various systems of space vehicles is compromise search between decrease in weight of a product, and, as consequence, decrease rigidity and strength properties of a structure. In the article the proposed option of a design of a deployable mechanical system. The basic load-bearing element is set of laminate composite panels, connected with joints. The main feature is additional elements (pipe or plate) com- bined with basic panels. The form of a sectional structure is equilateral triangle. Selection of the given type of a structure is proved by two kinds of analyses: the kinematic analysis of a deployment from a shipping rule in working, and the modal analysis for reliability acknowledgement on first eigenfrequency. The parametric analysis of geometry of a design is carried out, optimum versions are shown. For deeper optimization of design parameters it is necessary to carry out the following engineering analyses which have been not presented within the limits of the given article: the analysis of reliability of a deployment of mechanical devices; the structural analysis; the analysis of temperature deformations and so forth. The given design can be applied as the power basis to solar array, antennas, and cluster orbital systems.
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Design of the regions' economic development strategy
Статья научная
At present Russian economy is undergoing the similar trends of the modern economic development to those taking place in developed countries, those are globalization, advanced development of the service industries, post-industrial society formation, intellectual component expansion in the outcomes of any industry, informatization of the society, exhaustion of traditional sources of social and economic growth. In such conditions search for new ways and factors of the regional self-development is critical.
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Статья научная
Construction of communication spacecraft with large-size transformable antennas developed tendencies to increase the operational band frequencies, to reduce specific mass and to increase the overall dimensions of the structures. The improvement of technical performance of communication spacecraft with large-size antennas cannot be achieved with- out ensuring the required accuracy of antenna pattern and of the antenna gain coefficient at its maximum. Factors affecting the final quality of large-size structures for space application (of antennas in particular), keep influencing the products through all their service life - from design and production to tests and actual operation. The “direct” elimination of the negative factors affecting the final output is often unprofitable considering the present de- velopment of technological support in hi-tech industries. In this respect, control of the ultimate operational characteris- tics of large-size spacecraft antennas in conditions of real performance, and compensation, if necessary, of deviations from the required values, is optimal with respect to the output/cost ratio. This approach is practical in determining the onboard antenna pattern and compensating its operational distortions in the process of specified spacecraft performance. There are two methods of measuring the antenna pattern at the orbit. The first method is based on measurements of radio engineering characteristics obtained from ground space vehicles’ service stations. This method is sufficiently accurate, but it has several drawbacks. For example, this method increases the number of requirements to ground stations - their number, location and characteristics of the equipment in use. The second method bases on obtaining radio engi- neering characteristics from the configuration and orientation of antenna reflector. The reflector is imaged as a cloud of checkpoints reflecting the deviations of the construction’s configuration and orientation from the specified values. To obtain the antenna pattern measurements using the second method, an antenna configuration control system (ACCS) must be worked out for measuring the coordinates of the reflector surface points. To perform its specific func- tion, the system should have the following configuration: measuring equipment mounted on the spacecraft casing, and control elements fixed on the construction components. This configuration allows to present the antenna construction components in the form of checkpoint cloud. In the process of the system development the constructional analysis of the possibility of using the antenna configu- ration measurements for the its pattern calculation and for further assessment of its deviation from the specified values was made. This article presents the assessment of the required number of monitored checkpoints on the reflector sur- face. For this purpose, Ku-band of frequencies was chosen as one of the most common frequency bands used by telecommunication spacecraft. Several sets of points were considered, among them the sets belonging both to the deformed reflector profile and to the one without deformation. For each set the antenna pattern calculation was made. Visual representations of the focal beam and the directive antenna gain were compared. The analysis of the obtained data allowed to determine the necessary minimum of checkpoints for antenna pattern calculation with the required accuracy. The obtained data were taken into account in formulating the requirements for the system of orbital control of antenna configuration.
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Determination of total ionization dose by ray trace analysis based on a geodesic sphere
Статья научная
When designing the spacecraft, it is necessary to take into account the deleterious action of various factors in outer space. The main factor limiting active life of spacecraft is ionization radiation and it is the cause of most failures. Its influence is accompanied by ionization losses of the energy of charged particles in active and passive areas of semi- conductors and integrated circuits; that leads to emergence of radiation effects and it is characterized by the value of absorbed dose. At present there are several approaches to forecast the value of total ionization dose (TID): Monte- Carlo methods, methods that take into account only standard shield geometry (sphere, plane) and ray trace analysis (or sector-based analysis). The paper presents a modification of ray trace analysis that uses a geodesic sphere for sector construction and pro- vides regularly distribution of tracing rays in space unlike classical approach with using a parametrical representation of a sphere. Our approach enables to take into consideration real density of materials and allows using fewer sectors to meet the requirements of the method 154.PM-129 and keeping calculation accuracy. This is especially important for carrying out element-by-element radiation analysis taking into account heterogeneous protection through shielding of calculated point by elements of spacecraft design. This method is implemented as an extension for SolidWorks CAD. The input data for calculation are the following: 3d-model of equipment component as a part of spacecraft and radiation attenuation tables. The accuracy and the speed of the analysis depends on the number of tracing rays, and it is possible to carry out the calculation for several types of ionizing radiation at the same time. As an example of using the proposed method and a software module, we carried out radiation analysis of the block of the on-board digital computer for the spacecraft “Sfera”; its active life duration is 10 years on a high-elliptic orbit and 15 years on a geostationary orbit. As a result, we revealed that for the elements of the block minimum and maxi- mum total ionization doses differed substantially. It means that taking into account shielding properties of structural elements of device and blocks makes significant contribution to TID calculation.
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