Volume №1(21) / 2021
Articles in journal
The article deals with the formation of a methodological basis for the system analysis of mechanical oscillatory structures that reflect the properties of transport and technological objects under conditions of vibrational dynamic loads. The aim of the study is to develop a method of analysis and dynamic synthesis in the problems of dynamics of mechanical oscillatory systems, focused on detailing ideas about the formation of generalized relationships between the parameters of the system and evaluating the features of the resulting lever relations. Methods of the general theory of systems, in particular, the analytical apparatus of the theory of automatic control are used. It is shown that the introduction of transfer functions of interpartial connections makes it possible to construct a scheme for evaluating and using specific properties of mechanical oscillatory systems. A method is proposed in which a mechanical oscillatory system with linear properties and concentrated parameters can be interpreted as a dynamically equivalent automatic control system. The transfer function of the system is constructed on the basis of differential equations of motion obtained within the framework of the Lagrange formalism with subsequent Laplace transformation, which creates a convenient platform for evaluating the dynamic properties of the system. It is shown that the transfer function without special connections, when the frequency of the external disturbance is zeroed, displays the properties of the virtual lever under static loading conditions. A number of new concepts about the manifestations of the lever properties of a mechanical oscillatory system at fixed frequencies of external harmonic in-phase disturbances are introduced and considered. The proposed method is illustrated by a number of examples.
Information and mathematical technology for collecting and primary processing of spatial data is organized in the form of geoinformation monitoring (GIM) according to metatheoretical principles of the structure of spatially distributed commutation fields stratified (bundle) functionally connected spaces of constructive activity. This corresponds to the rules of information and mathematical support of CAD for creating spatial-graphic forms and thematic maps with different content. A layer of information interactions between different projects and users is formed around database of different distributed GIS. Individual database correspond to portals as nodes of communication of the user’s GIS with the global information diversity. The GIM technology is implemented on the example of the operational formation of a special GIS database and the construction of statistical graphs of the development of the novel coronavirus (COVID-19) pandemic at the national level. Processes and graphs are modeled in terms of reliability theory with the description of curves by probability density functions of the distribution of extreme events, of which the Frechet function of the time moments distribution for coronavirus disease detected cases in the population is optimal. The use of relative reliability indicators minimizes the impact of data errors, and their cross-country analysis indicates the presence of constant coefficients of the equations, which makes it possible to apply the epidemiological model in further studies of statistical data.
To improve the quality of transients in automatic systems with lag, a PI controller is used with a delay link that compensates for the integral component of the standard PI controller, which is designated in the technical literature as a proportional-integral difference controller (PIR controller). An important task facing the industrial implementation of this controller is to determine the optimal configurable parameters that deliver an extreme value to the accepted optimality criterion. The presence of a delay in the controller and the object makes it difficult to apply analytical approaches for the parametric synthesis of the control law, which provides transients with acceptable quality. This leads to the use of algorithmic methods. The article shows the application of the extended frequency response (RFC) method for the par-ametric synthesis of a PIR controller in a single-circuit automatic control system (ASR) by an object with a delay critical for the use of standard regulators. The RFX method allows you to obtain the values of the configurable parameters of the PIR controller, which in some complex cases can be used as the starting points of the gradient procedure. To assess the quality of the transient processes obtained by the RFC method, the overshoot coefficient and the integral quadratic criterion, which are widely used in the prac-tice of automatic control, are used.
The paper proposes a mathematical model of the operation of the station complex Irkutsk-Passazhirsky on the basis of the queuing theory. This model can be used to scientifically substantiate the planned measures during the reconstruction of this facility and to create of a regional transport interchange hub on its basis. We are used a BMAP model to describe a complex incoming passenger flow. BMAP makes it possible to take into account the presence of several substreams with different parameters. To describe the passenger service process a queuing network is used. It makes it possible to describe in detail the structure and movement of passenger flows within the system.
The problem of a thermal explosion in a medium with fluctuations in reactivity, which are specified through the distribution function for the activation energy, is formulated. A variational formulation is proposed for the differential equation describing the stationary temperature distribution in such a medium. Using a simple test function, the dependence of the variational functional on the value of the maximum temperature is numerically investigated. The critical conditions for a thermal explosion correspond to the appearance of an inflection point on this curve. Calculations show that an increase in the dispersion of the reactivity distribution the stability of the system decreases due to shift of the apparent activation energy of the chemical reaction.
The article deals with the development of renewable energy in the Republic of Belarus. A formalized model of the energy system of the Republic of Belarus has been built, a base of initial data has been collected for modeling energy production of electrical energy for a medium-term period in the MESSAGE program. Three scenarios for the development of renewable energy in the Republic of Belarus have been constructed, which provide for a different share of renewable sources in the overall structure of energy production. Forecasts of electricity production in the energy system of the Republic of Belarus for the period up to 2030 have been made according to the selected scenarios. A comparative analysis of the simulation results was carried out according to the following criteria: structure of energy production, volumes and structure of commissioned capacities, production cost of electric energy.
Nuclear power plants (NPPs), due to the accumulation during operation of significant amounts of radioactive products and the existence of a fundamental possibility of their exit in case of accidents beyond the envisaged boundaries, represent a source of potential danger or a source of risk of radiation exposure to personnel, population and the environment. The degree of radiation risk directly depends on the level of NPP safety, which is one of the main properties of NPPs, which determine the possibility of their use as sources of thermal and electrical energy. Probabilistic safety analysis (PSA) of a nuclear power plant is a complex, comprehensive systematic safety analysis, in the process of which probabilistic models are developed to determine the end states with damage to radioactivity sources and the end states of a nuclear power plant in excess of the established limits for releases of radioactive products and radiation impact on the population and the environment. environment and the values of probabilistic safety indicators are determined. The PSA results are used for qualitative and quantitative assessments of the achieved safety level, as well as for the development and adoption of decisions in the design and operation of NPPs.
The article is devoted to the description and analysis of the relationship between hard-to-solve problems and the process of forming programming paradigms that can be useful in solving such problems.The material for analysis is provided by the history of computer technology, as well as the inconspicuous line of scientific activity of the leader of programming A.P. Ershov in the field of manifestation and development of programming paradigms.The results of the analysis made it possible to systematize programming languages, present an assessment of their similarities and differences, which allows constructing laconic definitions regarding paradigmatic models.This makes it possible to stratify the presentation of the peculiarities of the semantics of programming language into autonomously developed components in the process of step-by-step development of experimental programming systems and the formation of schemes for studying and teaching system programming, which can be useful for increasing software performance. Along the way, a ranking of problem statements is formed according to the degree of their knowledge and stading, which affects the assessment of labor intensity.
The article deals with the actual problem of improving the design quality of large-scale information systems of public administration (KISGU). According to the author, the choice of acceptable parameters for the functioning of KISGU at the stages of its macro-design is constrained not so much by the lack of effective modeling methods as by the lack of convenient tools that allow one to acquire, accumulate and use heterogeneous knowledge for decision-making when building adequate models of a com-plex information system (IS). As a methodological basis for intellectual support for modeling and assessing the effectiveness of IS, it is proposed to use a complex DEA-model of assessment, built on the principles of structural, functional and territorial stratification of information on the functioning of a complex KISGU. A review of existing approaches to assessing complex IS and an analysis of various tools implemented on the principles of DEA-models made it possible to conclude that it is impossible to use them for assessing systems of the KISGU class. To support the examination procedure, the author proposes to develop a new web application using the Yii2 Framework. For this, the article describes the software architecture of an expert-oriented decision support system (DSS) and presents the results of its testing. As information support, we used open machine-readable data containing information on the characteristics of the functioning of the state budget management information system (ISUGB). The obtained results of the ISUGB assessment confirm the author's hypothesis about the possibility of enhancing the intelligence of an expert at the design stages through the use of special tools. The proposed approach can be used in the design of the system to select the parameters of the functioning of the ISUGB, in the audit of the effectiveness of the activities of institutions and as a practical guide for the training and retraining of IT specialists of specialized specialties.
Logical and associative rules are still the most common way to represent expert knowledge and support of decision-making. The use of rules in the case of inaccurate or uncertain information requires the development of specialized linguistic (language) means and software, providing their visualization and generation of source codes. In this paper, we propose a FuzzyRVML - an extension of a Rule Visual Modeling Language, designed for modeling logical rules containing elements of fuzziness. FuzzyRVML supports the fuzzy data type, the concepts of linguistic variable, term, and certainty factor. Descriptions of the main elements and constructs of FuzzyRVML are presented, as well as an illustrative example containing code generation in FuzzyCLIPS. Personal Knowledge Base Designer was used to support the notation proposed, as well for its implementation and evaluation.
The paper discusses the problem of preparing a computing environment for large-scale scientific experiments in the process of continuous integration of applied and system software. The environment is used both for launching scientific applications and for studying the functioning of digital twins of infrastructure objects. Such an environment is characterized by dynamic changes in the composition of resources, their characteristics, and requirements for them. Environment resources include computers, servers, virtual machines, and microcomputers. We need universal tools to automate the configuration of such resources. A comparative analysis of software configuration management tools (such as Chef, Ansible, Puppet, and SaltStack) of computational nodes in a heterogeneous environment is being performed. These tools are intended for automating the configuration of different nodes. Such automation reduces the setup time of nodes and increases the reliability of computations by minimizing the number of software and hardware failures, associated with the human factor in the manual configuration process. The considered tools are the basis for the further development of the instrumental complex for building an environment that provides the conditions for the functioning of digital twins of nature protection equipment. Based on the results of the comparative analysis and requirements of this framework, the Ansible framework was selected for further integration into the chain of continuous integration of applied and system software. Practical experiments have shown the advantages of using Ansible in comparison with other systems of a similar purpose.