Статьи журнала - Сибирский аэрокосмический журнал
Все статьи: 3183
On classes of functions with binary variables
Статья научная
The scheme proposed below is often used for solving problems and developing optimization algorithms. To solve a specific problem an efficient algorithm of optimization has been developed. The proposed algorithm combines several classes of problems by generelasing and determining a function class. For this reason establishing correlation among available classes of functions with binary variables in different experiments allows to apply even not perfect optimization algorithms. In this paper we consider a question on correlation of the function classes based on the different approaches to classification itself. First approach offers classes of separable, modular and submodular function; second one offers function classes based on structural features of the set of binary variables: monotone, unmonotone and w eakly unmonotone functions. It has been proven that separable functions are always unimodal and monotone ones. The results obtained in this study will allow to use a more efficient algorithm for optimization of separable and modular functions.
Бесплатно
On necessary and sufficient conditions of simply reducibility of wreath product of finite groups
Статья научная
A finite group is considered to be real if all the values of its complex irreducible characters lie in the field of real numbers. We note that the above reality condition is equivalent to the fact that each element of the group is conjugate to its inverse. A finite group is called simply reducible or a SR-group if it is real and all the coefficients of the decomposition of the tensor product of any two of its irreducible characters are zero or one. The notion of a SR-group arose in the paper of R. Wiener in connection with the solution of eigenvalue problems in quantum theory. At present, there is a sufficient amount of literature on the theory of SR-groups and their applications in physics. The simplest examples of SR-groups are elementary Abelian 2-groups, dihedral groups, and generalized quaternion groups. From the point of view of a group theory questions of interest are connected first of all with the structure of simply reducible groups. For example A. I. Kostrikin formulated the following question: how to express the belonging of a finite group to the class of SR-groups in terms of the structural properties of the group itself. Also, for a long time it was not known whether a simply reducible group is solvable (S. P. Stunkov's question). A positive answer to the last question was obtained in the works of L. S. Kazarin, V. V. Yanishevskiy, and E. I. Chankov. Questions concerning the portability of the properties of a group to subgroups, factor groups, and also their preservation in the transition to direct (Cartesian) and semidirect products or wreath products are always of interest. The paper proves that the reality of H is the necessary condition of simply reducibility of the wreath product of the finite group H with the finite group K and the group K must be an elementary Abelian 2-group. We also indicate sufficient conditions for simply reducibility of a wreath product of a simply reducible group with a cyclic group of order
Бесплатно
On nonparametric algorithms of object groups control
Статья научная
The paper is devoted to the identification and control of a group of both identical and varied objects. First the con- trol system of a local object is considered. Further on, all random factors acting in the measurement channels of an object are omitted and only the relationships between objects are preserved. Nonparametric algorithms of identification and control are given in a rather general form. The main attention is paid to different relationships between local objects. First the simplest case is considered, that is, a serial technological chain for whose control it is offered to use an external circuit of control when control influences in an external circuit play the role of a setting influence of local systems. The group of objects of a parallel-serial type is the following in complexity and here some feature inherent in many variables figuring in the corresponding section of a group of objects shows itself. This essential feature is that the output variables are measured with different discreteness, and the discreteness of control can significantly vary, includ- ing hours, shifts, days and weeks, depending on the nature of the production process and the scheme of measurement and control of corresponding variables. For example, the fineness of grinding in the production of cement is measured several times per shift, and the activity of cement showing its brand is determined only after 28 days. This circumstance should be taken into account when developing computer systems for identification, control and decision-making. The most difficult are such groups that fit into the scheme of interrelated objects, where feedback takes place in the technological process. The external control circuit can have a hierarchical structure, where the number of hierarchies is related to technical-economic, production-economic factors and in active systems to social factors as well. Control of such complexes is a complicated task, where the application of the theory of adaptive and learning systems is justified. This paper considers a class of algorithms of a non-parametric type, i.e. algorithms oriented to the case when informa- tion for describing objects is insufficient for parameterization, i.e. selection up to a set of vector parameters. Similar algorithms are presented in a rather general way. As a result, some cases of using control systems for groups of objects for thermal power plants are considered, and condensed information is provided for the metallurgical processing of the Norilsk Combine.
Бесплатно
On nonparametric control of a dynamic system
Статья научная
The paper considers the problem of dual control of an inertia-free object whose input is affected by a control vari- able and an observable but uncontrollable variable. The idea of dual control belongs to A. Feldbaum and was devel- oped on the basis of Bayesian approach. In this case, the probability densities of interference, as well as input output variables are known. In particular, the case of Gaussian probability densities was investigated. As a result, algorithms of dual control with the simplest objects of the inertia-free class were obtained. In the case of combined control systems, these studies were carried out by Feldbaum’s followers. Further development of dual control theory was described by Y. Tsypkin. The probability density of the interference was unknown, but the stage of selecting the structure of the control device and the equation of the describing object were necessary. In Tsypkin’s works, the corresponding parametric algorithms for dual control are given. In this case, a simultaneous estimation of the coefficient of the model and the regulator was made on the basis of the method of sto- chastic approximations. Later on nonparametric dual control algorithms were proposed. It is this way of control design that is discussed in the current paper. The parametric model of the object and the parametric structure of the controller were unknown in the problem statement. Nevertheless, it was known from a priori information that the characteristic of the object was one-to-one in control. Below we consider nonparametric control algorithms that combine the processes of simultaneous control and the study of the object with an accuracy of the structure unknown to the parameters, but a priori with a given number of delayed elements of the output variable of the object. In other words, the depth of the memory of the managed object was determined. In this case, a nonparametric algorithm for dual control can function in conditions of passive and active accumulation of information. The technique for representing a one-dimensional inertial-free dynamic system to a multidimensional static one is presented in the paper. Some results of numerical investigation of nonparametric algorithms of dual control are also presented.
Бесплатно
On nonparametric identification and dual control of quasilinear dynamic processes
Статья научная
The problems of identification and control of stochastic objects with a discrete - continuous technological process nature under conditions of nonparametric indeterminacy are considered. This term means a situation when the process structure with the accuracy to within parameters remains unknown. A more general class of dynamical nonlinear proc- esses, later of quasilinear processes, is investigated. The processes in this category are characterized by a low degree of nonlinearity, that is the superposition principle for this type of object is insolvent. Such processes often occur in vari- ous control loops for aerospace objects and systems. Nonparametric models where the dynamic process memory depth is specified on the basis of the selection of essential variables rule are given. According to this rule, the only variables included in the nonparametric model, at which the optimum blurring factor of the kernel is minimal. Nonparametric algorithms of quasilinear objects dual control are given. Control devices built on the basis of these algorithms not only perform the object control function directly, but also its study. The case when the control device corresponding to its inverse model “turns on” at the object input is considered. The process of dual control system training with active information accumulation is analyzed. The results of a numerical study of nonparametric models for quasilinear proc- esses with memory are presented in detail, as well as the results of a computational experiment using the algorithm of nonparametric adaptive dual control. In the simulation, objects characteristics were described by equations with different degrees of nonlinearity, the form of which was unknown, and which, during active information accumulation, were automatically restituted on the basis of the input-output variables process measurement. Also, the influence of various noise levels affecting an object and in measurement channels was investigated. The given computational ex- periments confirmed the possibility of using nonparametric algorithms for identifying and controlling of quasilinear systems.
Бесплатно
On properties of knapsack systems of information protection with the open key in ZP
Статья
Бесплатно
On remote sensing of the Earth by spacecraft
Статья научная
Remote sensing is a process which implies collecting information about an object. Due to their properties, satellite images are widely used in both practical and scientific fields. Satellite imagery is used in research aimed at the comprehensive study of natural resources, the dynamics of natural phenomena, and in the tasks of environmental protection. Special attention is paid to the use of space information for daily operational monitoring of the state of the environment in the implementation of geo-ecological monitoring of regions. In particular, this poses the problem to find the regions of the earth's surface with the characteristics determined by the considered parameters using the values of established parameters at certain points of the earth's surface. In this paper, we consider the special case of this problem when the given four points of the earth's surface determine the regions of the earth's surface (the so-called kernels of generalized squares) that have a specified configuration (square).
Бесплатно
On the concept of all electric propulsion spacecraft
Статья научная
Over the past several years the concept of the so-called “all electric propulsion spacecraft” has gained popularity among both customers and developers of geostationary (GEO) spacecraft; this issue is being actively discussed. The main advantages of the concept are the following: decreasing the mass of spacecraft and increasing its economic effi- ciency by means of pair orbital injection. There are some illustrative cases of implementation of this concept by Ameri- can, European and Russian companies. However, specialists interpret the content of the concept in different ways. That causes the problems connected to the development of the conceptual design of spacecraft. It is therefore very important to consider the concept in more detail, to compare various points of view in order to form understanding reflecting its essence the most accurately. At the same time, on the basis of the available examples, it would be feasible to analyze the advantages and disadvantages of this concept in comparison with other approaches to the construction of propulsion system of spacecraft. In the article we offer to interpret the concept as “ All electric propulsion spacecraft ”. This inter- pretation allows to understand its content unambiguously by the specialists of both Russian and Western Technical Schools. We offer to define “ All electric propulsion spacecraft ” as an apparatus that does not have in its composition an apogee engine unit that is chemically fuelled. It has to execute manoeuvres on geostationary orbit raising, orbit correc- tion and momentum wheel unloading by electrical propulsion only. We have shown that with the existing level of excel- lence of the equipment this concept does not have any advantages over the concept of separate propulsion subsystems for the correction and orientation by total mass as well as by the level of reliability.
Бесплатно
On the problem of the state anti-crisis policy instruments in Russia refinement
Статья научная
The article covers the main instruments, forms and methods for the state regulation of the market economy. It features the anti-crisis measures (instruments of anti-crisis state economic regulation) taken by the Russian Government to minimize negative consequences of the world financial crisis. The main macro-economic indices and some dynamic prognoses in Russia within the next few years are provided.
Бесплатно
Статья научная
The paper is devoted to cross-section geometrical parameters optimization of thin-walled spokes of large-size, um- brella-type deployable satellite parabolic antennas with radial spokes. The spokes in the structures mentioned above must have maximal bending stiffness and minimal mass. Spokes with uniform thickness of walls both in the section and along their lengths are not optimal to achieve the maximal stiffness while keeping predetermined mass, because they have the same bending stiffness in any direction. In the given paper the authors suggest changing the shape of the spoke cross-section by using sections of different thicknesses. This would allow increasing the bending stiffness of each spoke in the perpendicular to the antenna surface direction while preserving the same mass of the complete structure. The thickness will be increased stepwise in the cross-sectional areas of the maximum distance from each other in the bend plane; in the remaining part of the section it will be reduced. The main objective of this paper is to obtain analytical dependences for assessment of the bending stiffness of the cross section of the umbrella-type antenna spoke with a stepwise change in its thickness. Formulas were obtained within the framework of the beam theory of bending. The obtained analytical dependencies were verified by numerical simulation in the finite element software Ansys. Verification of the obtained results by numerical simulation showed good convergence with theoretical conclusions. The formulas obtained in the paper make it possible to give practical recommendations for design of large deploy- able space antennas with improved parameters, namely maximum stiffness with minimum mass of the structure.
Бесплатно
Optimizing the readability of tests generated by symbolic execution
Статья научная
Taking up about half of the development time, testing remains the most common method of software quality control and its disadvantage can lead to financial losses. With a systematic approach, the test suite is considered to be complete if it provides a certain amount of code coverage. At the moment there are a large number of systematic test generators aimed at finding standard errors. Such tools generate a huge number of difficult-to-read tests that require human veri- fication which is very expensive. The method presented in this paper allows improving the readability of tests that are automatically generated using symbolic execution, providing a qualitative reduction in the cost of verification. Experi- mental studies of the test generator, including this method as the final phase of the work, were conducted on 12 string functions from the Linux repository. The assessment of the readability of the lines contained in the optimized tests is comparable to the case of using words of a natural language, which has a positive effect on the process of verification of test results by humans.
Бесплатно
Orbital ordering probed by electron-spin resonance method in magnetic semiconductors
Статья научная
The temperature dependence of the electron-spin resonance in the 80300 K range temperature and magnetic field up to 5 kOe has been investigated in the substance of CoхMn1-хS solid solutions. From the temperature dependence of linewidth and g-value the orbital order is determined. The temperature hysteresis of ESR intensity in CoхMn1-хS is found at the cooling in the magnetic field and without it.
Бесплатно
Organization of complex testing of the spacecraft command and measuring system
Статья научная
In this article, we present the software for organization of complex testing of a spacecraft’s command and measur- ing system. The command and measuring system is responsible for communication of a spacecraft with the ground con- trol complex. The developed software is designed for the support of interaction between the automated testing complex of a spacecraft and test and control equipment of the command and measuring system. Complex tests include testing of all or a part of conjugate elements of a spacecraft, united in a single system, with simulation of regular and possible non-standard modes of operation. Complex tests of the command and measuring system are carried out using an auto- mated testing complex, the main task of which is transferring of the control commands to the test and control equipment of the command and measuring system. The automated testing complex also receives packages from the test and control equipment containing telemetric information about the state of the on-board systems of a spacecraft. During complex tests of the command and measuring system, the developed software supports the exchange of command and telemetry packages between the automated testing complex and test and control equipment. The developed software is built in the software of the test and control equipment as a subsystem for organizing of complex testing. The subsystem receives commands from the automated testing complex, identifies and sends them to the test and control equipment, in the form of a structure that is understandable to the command and measuring system. For each command, the subsystem produces a receipt of successful identification or of an error if it occurs. The subsys- tem receives telemetry from the command and measuring system, converts it in accordance with the protocols of inter- action and sends it to the automated testing complex. In addition to the command and measuring system’s telemetry, the telemetry of the test and control equipment is sent to the automated testing complex. It contains the parameters of the sensors of various equipment that are part of the hardware and software complex, as well as the parameters required for transmission channels’ settings between the test and control equipment, command and measuring system and other systems of a spacecraft. All actions occurring during the process of complex testing are recorded in the test report. All protocols of tests are saved and can be replayed.
Бесплатно
Статья научная
A mathematical model of the aircraft avionics thermal state describing the heat exchange of the onboard equipment housing with a honeycomb structure made of a carbon fiber composite, the process of heat transfer of the onboard equipment elements and the air is developed. The considered heat transfer process in a heterogeneous medium is de- scribed by the boundary value problem for the heat equation with boundary conditions of the third kind. To solve the direct problem of the onboard equipment housing with a honeycomb structure thermal state, the Monte- Carlo method on the basis of the probabilistic representation of the solution in the form of an expectation of the functional of the dif- fusion process is used. The inverse problem of the honeycomb structure heat exchange is solved by minimizing the func- tion of the squared residuals weighted sum using an iterative stochastic quasigradient algorithm. The developed mathematical model of the onboard equipment in the unpressurized compartment thermal state is used for optimizing the temperature and airflow of the thermal control system of the blown onboard equipment in the unpressurized com- partment of the aircraft.
Бесплатно
Статья научная
Principles of construction and functioning of management system by the enterprise of service sphere in conditions of the market, are considered. The model of relationships between causes and effects, reflecting influence the administrative actions on business-processes, that maintenances the appeal of firm's services is presented. The technique of estimation of quality of management system by the service firm is resulted.
Бесплатно
Статья научная
In the given work the problem of semantic decompression patterns addition to the meaningful sentences generated as functions in multidimensional vector space of the notions of the natural language is considered. The model of adding semantic decompression patterns based on stylistically-oriented sets of generative grammar rules is offered. The complexity of natural language translation problem is discussed. The considered model provides the algorithm of adding semantic decompression patterns that can be used for improving the performance of educational tasks generation software.
Бесплатно
Problems of managing reproduction of defense-industrial fund at the machine-building enterprises
Статья научная
The basic problems of managing reproduction of defense-industrial fund at the machine-building enterprises are considered by the authors.
Бесплатно
Статья научная
The statistic analysis results of cases correlation of abnormal functioning of SC with increased levels of geomagnetic activity are represented in the article. The main results of completing work package in JSC “ISS” to research negative influence of space environment on SC, and the main results of the development of the protective means and methods are described in the article.
Бесплатно
Procedure for evaluating the effective use range of the unified space platforms
Статья научная
In JSC “ ISS ” the task of evaluating the efficiency of using the previously developed unified platforms for the creation of a new spacecraft was solved in a more empirical way, by generalizing the reserve for existing developments and as- sessing opportunity and expediency of applying the existing reserve in the future (continuity of development). However, the methodological basis for solving this kind of problem has not been developed to this day. From this follows the con- clusion about the urgency of developing a methodology for assessing the range of effective application of the unified space platform and the need for its implementation. In this article, the methodical approach to problems of expediency of use of existing unified space platforms for creation of new space vehicles on their basis is considered. The sources of uncertainties arising in the design of space vehicles and the stages of choosing the optimal project under conditions of uncertainty are determined. This article describes such a design approach of space vehicles as a rational design. The main task of this approach is indicated. Also in the article the design parameters that determine the structural stability of the spacecraft are listed. A mathe- matical model of a spacecraft based on a unified space platform has been developed, which determines the dependence of design parameters on the characteristics of the payload. The criterion of a space vehicle optimal design based on a unified space platform, defined as the ratio of the effi- ciency index to the cost index for the creation of a spacecraft, is formed. A methodology for assessing the range of effec- tive application of unified space platforms has been developed. Approbation of the developed technique was carried out based on existing geostationary space communication apparatuses on the basis of a unified space platform ”Express-1000NT”, developed by JSC “ ISS ”. Calculated data and graphical representations of effective application ranges of the unified space platform “Express-1000NT” are presented. Based on the results of approbation, it can be concluded that the developed methodology allows to asses properly the range of effective application of unified space platforms for communication satellites in the geostationary orbit.
Бесплатно
Process of service products creation: logistical approach
Статья научная
The logistical approach to solving a complex problem, in particular, creation of new service products is considered. The logistical approach is based on increase of service technologies flexibility and allows to adapt them for current changes within demand for rendered services. Application of the present approach requires development of various variants of effective business processes of service in order to avoid eventual “failures” during the process of service product consumption by the consumer. Urgency of the article is caused by increasing demand of the society for qualitative services including tourist services.
Бесплатно
