Informatics, computer technology and management. Рубрика в журнале - Siberian Aerospace Journal
Статья научная
Inspection of underwater objects, such as underwater archaeological sites, sunken technical objects, and un-der water located technical structures, requires the use of specially trained divers, manned or unmanned, re-motely operated or autonomous underwater vehicles. A relatively rarely used design for such underwater vehicles is a design in the form of a quadrotor with posi-tive buoyancy. This article discusses the design and the control system of the remotely operated underwater vehicle in the form of a quadrotor. The aim of the work is the selection and justification of the shape of the vehicle, the selection of the optimal structure of the control system with the expectation of the subsequent use of the vehicle as an au-tonomous one. The potential advantages of the selected design in the form of a quadcopter with a cylindrical body are de-scribed, in particular, the large volume of the sealed space of the vehicle, the possibility of installing capacious power sources, the potential for stabilizing the vehicle in a given position if there is a current at the place of work. The sealed case of the device is designed to place control electronics, power electronics and battery power of the device. The selection and justification of the shape of the sealed enclosure were made using a hydrostatic modeling apparatus and theoretical mechanics. A solid cylinder made of polycarbonate was selected as a form of the sealed housing of the vehicle. The advantage of the selected form in comparison with the parallelepiped-shaped case is shown under the condition of the same material parameters. The control system of the device includes software and hardware components. The choice of hardware com-ponents is justified, their key characteristics are described. As the control device of the top level, a single board computer (SBC, Single Board Computer) Orange Pi PC was selected, the direct control of the motor of the vehi-cle is performed using the Cortex-M3 microcontroller. The software architecture of the device is described. The choice of architecture is determined by the requirements of poorly connected components (which makes it easy to replace particular software elements without the need to modify the other elements), the simplicity of the potential replacement of the top-level control modules (which potentially allows switching from a remote control model to an autonomous control model). Some software components are described. The control system is implemented with the high-level lan-guage Python version 3.7, the basis of the control mechanism is message passing, the MQTT protocol maintained by the Mosquitto server is selected as a messaging mechanism. Testing of the vehicle was carried out in pools with standing water and with a simulated current. Testing showed the need to gain experience to control the underwater vehicle. The study will allow us to further develop a new version of the underwater vehicle, taking into account the wishes and identified problems.
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Today, there are many approaches to developing parallel programs. It is considered that it is more efficient to write such programs for a particular computing system. The article proposes to ignore the features of a particular computing system and outline plans for the development of a certain automated system that allows trying to improve code efficiency by developing programs with unlimited parallelism, as well as explore the possibility of developing more efficient programs using the restrictions imposed on maximum parallelism. This approach was demonstrated on the example of the analysis of various matrix multiplication algorithms. As a mathematical apparatus, the study considered various approaches to the description of algorithms to increase their implementation, including an approach based on unlimited parallelism and, also, an approach based on various restrictions on parallelism is proposed. In the course of the work, sequential and parallel methods of matrix multiplication were studied in detail, including tape and block algorithms. As a result of the study, various matrix multiplication methods (sequential, with left and right recursion, parallel methods) were studied and more effective ones were found in terms of the resources used and the restrictions imposed on parallelism. A sequential method and a cascade summation scheme were analyzed and proposed as possible ways of convolving the results of solving the problem obtained after the decomposition stage. Also, a number of programs with different levels of parallelism were developed and implemented in the functional-stream parallel programming language. In the future, such transformations can be carried out formally, relying on a knowledge base and a language that allows equivalent transformations of the original program in accordance with the axioms and algebra of transformations laid down in it, as well as replacing functions that are equivalent in results and have different levels of parallelization. These studies can be used to increase the efficiency of developed programs in terms of resource use in many branches of science, including in the field of software development for the needs of astronomy and rocket science.
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Saint-Venant and Karman equations for an orthotropic pre-stretched plate under tem-perature
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Thin plates that are preliminarily stretched with the help of forces in their plane and attached to rigid ribs are used in space technology. In fire rescue technology, plate designs are being developed that repre-sent a life net supported by drones to cancel the energy of a person falling from a height during his evacua-tion both from a high-rise object and in other exceptional cases. The plates are thin and usually consist of a composite material. Shear forces predominate as loads; to reduce deflection, the life net is pre-stretched onto a rigid contour. In this work the equations of B. Saint-Venant and T. Karman for an orthotropic plate are obtained, tak-ing into account the temperature increment. The former are the equations of equilibrium in displacements with initial forces, and the latter are a system of non-linear equations of deformations continuity and non-linear equations of equilibrium. The form of models’ representation is differential. Examples of plate calculation for the action of a concentrated force and preliminary stretching are con-sidered. The plate continuum is replaced by a discrete region; differential ratios are replaced by finite-difference analogs. Nonlinear equations were solved by iterations. The calculation of a thin plate for the action of a concentrated force showed that the resulting longitudinal forces are so large that the stresses are two to three orders of magnitude higher than the stresses allowed for the considered orthotropic material. To reduce stresses, the plate is pre-stretched. The bending surface be-comes more monotonous, the deflection decreases, which leads to a decrease in the stress level. Comparison of calculations obtained from the action of a concentrated force and temperature changes showed that in this flexible plate of small thickness, the effect of temperature exposure is insignificant. The apparatus of the Karman theory is relatively complex in numerical implementation. The mixed form of the model in stresses and displacements requires additional studies of the convergence of solutions. The Saint-Venant deformation model as a model of a flexible plate with a small deflection makes it possible to solve the problems of ensuring the rigidity and strength of a complex longitudinal-transverse bending of orthotropic plates.
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Savostyanova I. L. 3-dimensional solutions from two variables
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In this paper, we consider stationary 3-dimensional equations of ideal plasticity with the Mises flow condition. The material is assumed to be incompressible. The case when all three components of the veloci-ty vector and hydrostatic pressure depend only on two coordinates x, y is studied in detail. For this case, a new name is introduced – 3-dimensional solutions from two variables, to distinguish it from the generally accepted two-dimensional state, when only two components of the velocity vector and hydrostatic pressure differ from zero. It is proved that the system admits, in the sense of S. Lie, a Lie algebra of dimension 10. It is shown that all 3-dimensional solutions from two variables is a superposition of the plane stress state and plastic torsion around the z-axis. Two invariant solutions of the equations describing the 3-dimensional deformed state are constructed. The first solution can be used to describe plastic flows between two rigid plates that approach at different speeds. The second solution is used to describe the stress-strain state of the material inside a flat channel formed by converging plates.
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Search for broadband signals ground-based radio navigation system
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In the present paper, a method of temporary search for broadband of frequency manipulation with minimal shift keying (MSK) signals of ground-based radio navigation systems (RNS) is considered. The method is based on a multi-alternative optimal signal detection (the signal may belong to one of the orthogonal signals) using the evaluation-correlation principle of processing (ECPP) under conditions of a priori uncertainty. The problem of representing broadband MSK signal as a signal with double discrete frequency-phase modulation (FPM) was solved. The law of phase manipulation in the form of a binary sequence of elements lb of a length code τ э L (in the “Sprut” RNS, 16383 L , 2.5 э mcs is the duration of the signal element) is defined through the law of frequency manipulation in the form of a binary sequence of elements ld of a known length L code. The representation of the signal in the form FPM allows, during correlation processing, to replace the correlation integral on the interval [0, τ]э L by L the sum of correlation integrals on the intervals [0, τ]э or by L the sum of element-by-element correlations. The calculation of element-by-element correlations allows the use of a matrix apparatus for the ECPP of the analyzed signal. With the technical implementation of the “search” procedure, there is no need to form 2L pairs of reference quadrature signals with the length L of the modulating code, and instead of that a pair of element-by-element correlations is memorized and over time τэ , according to a code element lkd , cyclically shifted by 1 k elements, frequency manipulation and a code element klb , cyclically shifted by 1 k elements, phase manipulation, block-by-block accumulation L of quadrature correlations is performed. The use of upper-left and lower-right triangular matrices with binary elements klb makes it possible to search for broadband MSK signal with additional phase manipulation of a discrete information message. The structure of the optimal algorithm of parallel search for ECPP of the broadband MSK signal with the use of a matrix apparatus, which allows to implement the optimal algorithm “of search” during the duration τэ L of the signal in real time.
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Self-Configuring Genetic Programming Algorithms with Success History-Based Adaptation
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In this work, a novel method for self-tuning genetic programming (GP) algorithms is pre-sented, based on the ideas of the Success History based Parameter Adaptation (SHA) method, originally developed for the Differential Evolution (DE) algorithm. The main idea of the method is to perform a dy-namic analysis of the history of successful solutions to adapt the algorithm's parameters during the search process. To implement this concept, the operation scheme of classical GP was modified to mimic the DE scheme, allowing the integration of the success history mechanism into GP. The resulting algorithm, de-noted as SHAGP (Success-History based Adaptive Genetic Programming), demonstrates new capabilities for parameter adaptation, such as the adjustment of crossover and mutation probabilities. The work also includes a detailed review of existing self-tuning methods for GP algorithms, which allowed for the identi-fication of their key advantages and limitations and the application of this knowledge in the development of SHAGP. Additionally, new crossover operators are proposed that enable dynamic adjustment of the crossover probability, account for the selective pressure at the current stage, and implement a multi-parent approach. This modification allows for more flexible control over the process of genotype recombination, thereby enhancing the algorithm's adaptability to the problem at hand. To adjust the probabilities of applying various operators (selection, crossover, mutation), self-configuring evolutionary algorithm methods are employed, in particular, the Self-Configuring Evolutionary Algorithm and the Population-Level Dynamic Probabilities Evolutionary Algorithm. Within the framework of this work, two variants of the algorithm were implemented – SelfCSHAGP and PDPSHAGP. The efficiency of the proposed algorithms was tested on problem sets from the Feynman Symbolic Regression Database. Each algorithm was run multiple times on each problem to obtain a reliable statistical sample, and the results were compared using the Mann–Whitney statistical test. The experimental data showed that the proposed algorithms achieve a higher reliability metric compared to existing GP self-tuning methods, with the PDPSHAGP method demonstrating the best efficiency in more than 90 % of the cases. Such a universal self-tuning mechanism can find applications in a wide range of fields, such as automated machine learning, big data processing, engineering design, and medicine, as well as in space applications – for example, in the design of navigation systems for spacecraft and the development of control systems for aerial vehicles. In these areas, the high reliability of algorithms and their ability to find optimal solutions in complex multidimensional spaces are critically important.
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Semi-analytical method for calculating elastic-hydrodynamic contact
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A semi-analytical method for calculating elastic-hydrodynamic contact based on the partial use of Computer Aided Design / Computer Aided Engineering (CAD / CAE) packages and solutions of the integral equation of functional relationship between pressure and deformation have been described. The pressure in the lubricating layer is described by solving the modernized Reynolds equation taking into account the factors such as elastic deformation of surfaces in the contact zone, cavitation effect in the low-pressure region, and variable viscosity of the lubricant layer, which depends on thermodynamic parameters. Based on the stationary solution, a tensor damping coefficient has been obtained, with the help of which calculations of transient non-stationary modes that occur in cases of a sharp change in the external load have been further performed. A comparison of the results of modeling a plain bearing obtained by using the proposed semi-analytical method has been made and the full calculation performed using CAD / CAE programs such as ANSYS and COMSOL Multiphysics. The comparison showed good convergence of all numerical methods. At the same time, the “hybrid” method showed a number of advantages over direct calculations in CAD / CAE packages, such as: faster calculation speed, low requirements for computing resources and accounting for the cavitation effect. The described semi-analytical method allows to create digital twins of bearing units, centrifugal pumps and hydraulic supports used in satellite cooling systems and in rotary mechanisms of ground-based satellite dishes.
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Simulation computer model for virtual research of optoelectronic measuring systems
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The paper considers a simulation computer model of an optoelectronic system for measuring the point objects coordinates. The model allows optimal coordination of the system links parameters in order to minimize the measurement error. The method of multiple statistical tests which allows accumulating the results of single computational experiments for each specific measurement event with a unique random distribution of links parameters and characteristics, and then carrying out statistical processing of the accumulated results is the main method of computer simulation. As a result of multiple analyses, multi-parameter functional dependencies that provide optimal coordination of parameters controlled by the designer or operator according to the criterion of the resulting measurement error minimizing are realized. The article presents the results of evaluating modeling parameters that reduce the measurement error. It is relevant to apply this method when using the same measuring system in different operating conditions, for different measured objects and when performing various functional tasks since it allows adapting the system for a specific application. The model presented in the article can be concretized for the purpose of evaluating and multi-parameter optimization of particular object parameters, as well as for developing a virtual measuring stand on the basis of the model and its modifications.
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The implementation of efficient communication systems with high data transfer rates requires the usage of signals with a high modulation order. Current trends in the development of communication systems are aimed at orthogonal frequency multiplexing of signals (OFDM – Orthogonal Frequency Division Multiplexing) usage, which allows you to flexibly change the data transfer rate, to reduce the frequency resource by improving spectral efficiency, as well as to combat frequency-selective fading and selective interference. However, the price of such a solution is also high. The high peak-to-average power ratio (PAPR) OFDM signals imposes a requirement for the linearity of the analogical path, significantly reducing the efficiency of the transmitter and receiver output amplifiers, increasing the dimensions and power consumption of the communication system as a whole. The practical novelty of the work lies in the possibility of using the developed method for reducing the PAPR factor in systems with complex communication channels, such as troposcatter and near-field magnetic induction communication systems, where significant effect of selective interference, intersymbol interference, and frequency-selective fading is present. The results of this work give the opportunity to navigate a large number of algorithms for reducing the peak factor of OFDM signals and apply the desired algorithm in a specific task.
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Obtaining electricity from renewable energy sources is primarily due to the exhaustion of traditional natural energy sources, such as coal, oil, gas. Today it is a promising area of development. The adverse impact on the environment of the use of traditional energy technologies is well known and scientifically proven. The use of traditional technologies inevitably leads to climate change, so the topic of the transition from traditional to alternative energy sources is undoubtedly relevant. Using of solar power plants with photovoltaic modules recently has gained relevance. However, the efficiency of such installations depends largely on their correct orientation to the Sun: the more precisely the system is installed, the more energy it will be able to convert. This article presents the results of the development of a simulation model of the solar panel orientation control system. To maximize the production of solar energy, the control system with tracking the Sun is built using fuzzy logic: fuzzy rules are formulated to control the positions of the object relative to the vertical and horizontal planes. The use of fuzzy logic is based on the product model of knowledge, which implies the use of linguistic variables to avoid the limitations inherent in classical product rules. The use of fuzzy control allows to correct the movement of the panel in the shortest time in the autonomous mode, thus reducing the arising power losses. Russian SimInTech dynamic simulation environment for technical systems is used as the system development environment. Simulation model is represented by several subprojects, united in a single database. The system model is implemented using standard blocks and a set of submodels, as well as a programming unit. The result of the work can be tracked in the 3D module of the built-in visual editor, which allows you to display the interaction of three-dimensional models objectively. In order to simplify and more finely implement the work of the project, a system of loading data, sunrise and sunset points, from an external Excel file was used.
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Статья научная
The development of unmanned aircraft systems is becoming one of the key areas of Russia's scientific and technological development. Within the framework of the approved strategy until 2030, it is planned to form a new industry specializing in the creation and use of civilian drones, and priority areas for the development of unmanned technologies have been identified. The great potential for the use of unmanned vehicles is observed in the creation of geospatial databases. In this connection, when using autonomous aerial platforms for aerogeophysical works, the issues of improvement and development of information-measuring systems used on such carriers, as well as the issues of training of operators of aerogeo-physical systems become relevant. The development of algorithmic and software of information-measuring systems on the basis of implementation of previously created electronic content: reference materials, instructions for work, operation of instrumentation products, protocols for processing of obtained results, decisionmaking techniques, etc. is becoming important. However, the application of such electronic content carries risks of reducing the quality of surveying works. One of the ways of risk assessment is to combine the traditional qualitative and categorical approach of modern risk management with multilevel representation of the hierarchy of aggregation of expert-assessed risks in the composition of summary and integral risks by applying the apparatus of soft computing. For systematization and prioritization of risks it is proposed to use gradation scales and terms of linguistic variables of risk components associated with the probability of occurrence of a decrease in the quality of content of information support of operator training systems, with the potential value of possible damage in the event of the fact of a decrease in the quality of information support. As a result, it becomes possible to develop a risk-assessment model, which is a procedure for the specific construction of matrices of consequences and probabilities for individual risk-indicators of the assessment of the integration of electronic content in the information support of training systems for operators of information-measuring systems of aerogeophysical applications. This procedure is a logical basis for calculation of summary and integral values of risk-indicators of assessment, as well as gradation of risk levels.
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Software system for mathematical simulation of the electronic beam welding process
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Within the framework of this study, a software system for modeling the distribution of the temperature field in the steady-state mode of the electron-beam welding process for thin-walled aerospace structures is proposed. The purpose of creating such a software system is to improve the quality of control of the electron-beam welding process and, accordingly, to reduce the number of defects in welded joints of thin-walled structures. The software system has a model structure and implements the energy distribution models proposed earlier by the authors. The MySQL database management system and the Embarcadero RAD Studio programming system were chosen as the means of implementing the program. The central link of the system is a database that allows you to store and process information both on mathematical modeling and on the results of simulation and field experiments. The article describes the structure of the developed software system, and also presents algorithms for the operation of its constituent modules. The system provides the user with the opportunity not only to carry out simulation according to the specified technological parameters (welding speed, accelerating voltage, beam current, boundary conditions, simulation time, product material), but also to visualize the results and save them in a single database. The use of the proposed system allows not only to minimize the costs of the enterprise for the development of technological parameters of the steady state for the electron-beam welding process, but also to create a flexible information base for collecting experimental information with the aim of further automating and intellectualizing the technological process of creating permanent joints in the framework of Industry 4.0.
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In this paper, we consider the solution of the filtering problem using the Kalman filter with the optimal tuning of the radio-reflecting net. A large-sized transformable space-based reflector is considered. In the process of this structure placing in orbit, it is possible that the real form of the radio-reflecting net can deviate from the desired one. To ensure point-to-point adjustment of the active part of the mesh, a cable-cable system is used. The nodal points of the radio-reflecting surface are connected to the back side of the net through cables. They have built-in actuators that allow one to change the length of the cables. A piezo actuator was selected as a control device. By point-by-point adjustment of the piezo actuators the net is stretched to the required shape. This ensures a high-quality radiation pattern and a high signal level when receiving and transmitting data. Specific values of the disturbing influences are given. To measure the supply voltage on the piezo actuator and the cable length, a voltage converter and a laser scanner are used. Possible deviations from the calculated initial position are determined. In accordance with the principle of separation, the estimation problem is solved first, then the control problem. The estimation problem is solved using the Kalman filter. The control problem is solved using the optimal control algorithm according to the hierarchy of target criteria. The results of numerical simulation are presented. The successful solution of the problem is shown with variable values of measurement noise and disturbing influences. Comparison with trajectories obtained applying various optimal control algorithms is given.
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Failures of elements during the operation of technical and many other systems are, as a rule, random in nature. This leads to various models of the recovery process, studied in probability theory and mathematical reliability theory. During the restoration process, failed elements are restored or replaced with new ones, and there is often a change in the costs and quality of the restored elements (time-to-failure distribution functions). The work examines the cost function (average cost of restoration) in the process of restoration of order k1, k2 , in which, according to a certain rule, the costs of each restoration and the distribution functions of operating time change. Considering, that the recovery function (average number of failures) is well studied in reliability theory, a solution to the integral equation for the cost function is obtained through the recovery function of the model under consideration. For the order restoration process 1 2 k , k , a formula is obtained for calculating the cost function through the restoration function of a simple process formed by the convolution of all distribution functions of the periodic part. For practical application, explicit formulas are obtained for the cost function during the restoration process, in which the periodic part is distributed according to an exponential law or an Erlang law of order m with the same exponent α. The resulting formulas can be used to study the properties of the cost function and solve optimization problems in strategies for carrying out the restoration process in terms of price, quality, risk, if, for example, the average number of failures is taken as quality, the average cost of restorations as price, the dispersion of the number of failures as the risk, or cost of restoration.
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Solution to the first boundary value problem of plane elasticity theory using conservation laws
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A huge number of works are devoted to solving boundary value problems for the equations of plane elasticity theory. The largest number of studies in this area are based on the formula found by G. V. Kolosov. He was the first to express the general solution to the problem of plane elastic deforma-tion by finding two independent functions of a complex variable. This made it possible to apply a welldeveloped theory of analytic functions to solving problems of elasticity theory. Later, the solution method based on Kolosov's formula was developed by his student N. I. Muskhelishvili. But the described method also has significant limitations. It is applicable only to those areas that can be conformally mapped onto a circle. Therefore, other methods for solving elasticity theory problems are also needed, since a large number of practically important problems are solved for areas that do not satisfy this condition. The method developed in the work is based on the use of conservation laws that are constructed for equations describing a plane deformable state. The assumptions made in the work make it possible to construct a solution to the first boundary value problem for arbitrary plane areas bounded by a piecewise smooth contour. In this case, finding the components of the stress tensor is reduced to calculating contour integrals along the boundary of the region under consideration. As in the case considered by G. V. Kolosov, the solution to the problem is based on two exact solutions of the Cauchy – Riemann equations, which have singularities at an arbitrary point in the region under consideration.
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Статья научная
The plane problem for elasticity equations is well studied. It can be explained by its importance for applications and by the fact that the equations can be reduced to the Cauchy-Riemann system. In spite of this importance, exact solutions that would describe the stress-strain state of bodies of finite dimensions are not numerous. Conservation laws for differential equations have been appeared more than a hundred years ago, but, as a rule, they were not used to solve specific problems, but were of purely academic interest. The situation changed with the development of the technique of construction of conservation laws for arbitrary systems of differential equations, and then with the use of conservation laws to solve boundary value problems of the theory of plasticity and elastic-plasticity. In this article, new conservation laws are constructed for the equations of the plane theory of elasticity in the stationary case. These laws form an infinite series, which is closely related to the elasticity equations solving. This fact made possible to reduce solving of boundary value problems, in terms of displacements, to the calculation of contour integrals along the boundary of a domain bounded by the studying elastic body. As it follows from the proposed technique, the studied area can be multiply connected, and the considered boundary can be piecewise-smooth.
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Solving the problem of stretching an elastic-plastic strip weakened by cuts and holes
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In this paper, the boundary between elastic and plastic regions in a stretchable strip is con-structed. The band is weakened by side slits and holes. Such tasks are still relevant, since its solution allows us to make an assessment of the limiting state of the structure under consideration. Cuts can have an arbitrary shape, their number is not limited. For simplicity, only sections with rectilinear boundaries are considered in the article. The holes may have an arbitrary shape and be located anywhere in the strip. In operation, only circular holes are considered for simplicity. Numerical methods are currently very often used to solve such a problem, unfortunately, often without much justification. Therefore, analytical methods for solving such problems are becoming more and more relevant. In this paper, the conservation laws of differential equations are used. The conserved current is linear in the first derivatives. The task is solved in two stages. At the first stage, Dirichlet is solved for the Laplace equation, and at the second stage, the technique of conservation laws is used. Their use makes it possible to reduce the finding of the components of the stress tensor at each point to a contour integral along the boundaries of the region un-der consideration. And this makes it possible to build an elastic-plastic boundary.
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The article presents the problem of optimizing the structure of information processing computer appli-ances for real-time control systems used, among other things, in the rocket and space industry. In addition, the features of this problem that affect the choice of optimization methods are studied. It’s concluded that this problem can be effectively solved using evolutionary optimization methods. Existing performance models allow you to determine the minimum hardware configuration of a multi-processor computing system. The approach proposed in this article allows us to find configurations that have hardware redundancy (compared to the minimum configuration), but, due to this, have a greater probability of being in states that provide performance sufficient to achieve the goals of functioning of the designed real-time control system. The described approach is more flexible than simply duplicating all hardware components of the minimum configuration, which can be used to reduce the cost of creating and operating the designed control system. The proposed model can be used to optimize the performance of multiprocessor hardware and software complexes of real-time control systems. At the same time, it should be taken into account that the resources allocated for the creation and operation of the hardware and software complex are always limited. There-fore, it is advisable to consider the problem of performance optimization as a multi-criterion: one criterion will be performance, and the other-the cost of creating a hardware and software complex.
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The S-box is the most important component of modern cryptographic algorithms which largely determines the quality of cryptographic transformation. The modern method of estimating the S-boxes quality employs their representation as component Boolean functions to which cryptographic quality criteria are applied. Such criteria include: nonlinearity, correlation immunity, an error propagation criterion, and a strict avalanche criterion. Nevertheless, it is obvious that a cryptanalyst is not constrained in the ways of representing the cipher components, in particular, using the functions of many-valued logic. The design features of modern cryptographic algorithms allow their representation in the form of 4-logic functions, which determines the need to research cryptographic properties of the S-boxes represented as component 4-functions. In the literature today there are methods for measuring the nonlinearity of 4-functions; nevertheless, there are no similar methods for researching the differential properties of 4-functions, in particular, involving their compliance with the strict avalanche criterion. In this paper the strict avalanche criterion is generalized to the case of 4-functions and the compliance of the S-boxes component 4-functions of the “Magma” cryptoalgorithm to the strict avalanche criterion has been researched. All balanced 4-functions of length N = 16 satisfying the strict avalanche criterion were synthesized using the restricted brute-force method. The basic properties of the constructed class of 4-functions are determined, and bijective S-boxes based on them are constructed. It has been established that S-boxes of length N = 16 satisfying the strict avalanche criterion, both in terms of component Boolean functions and in terms of 4-functions, also possess optimal nonlinear properties. This circumstance allows us to recommend S-boxes satisfying the strict avalanche criterion of component 4-functions for use in modern cryptographic algorithms.
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Structure, network protocols of the internet of things for quality production control
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The subject of research is the model and structure of the Internet of things (IoT) network for product quality control in industry and agriculture. The purpose of the article is to analyze communication protocols and structures of IoT networks. The method of analysis and structural design of IoT networks is applied. The field of application is automation of monitoring products of enterprises of the aerospace industry. The article provides an overview and analysis of existing IoT technology; it considers the protocols and composition of IoT networks, and provides variations in the structures of building such networks. 4 levels of IoT architecture are described, as well as the communication protocols are used. The directions of building the Internet of things network for product quality control are defined. A multi-agent model of such system is presented, for the implementation of which the structure of the IoT network is given. The structure of a multi-agent system (MAS) for monitoring product quality in industry and agriculture includes many agents, such as product quality agents, communication agents, database agents, agents for analyzing information received from sensor agents, and decision-making agents. This MAS implements functions to ensure the required class of product quality and it is based on building a local network of the Internet of things. The research proposes an algorithm for processing information in such an IoT network. Analyzers (sensors) product qualities will be periodically polled and their values will be recorded in the server database. The decision-making subsystem sends data on product quality compliance to the enterprise administrator on a mobile device. The server structure is implemented using cloud IoT platforms, for which a brief overview is provided. The one IoT network implementation is developed using LTE NBIoT technology. This approach can be used in the aerospace industry for product quality control within automation 4.0.
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