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Journal archive

№4(94) August 2021 year


IT management

Performance management

The effectiveness of design solutions largely depends on the promptness of processing a large amount of data from various sources, which determines the feasibility of using information decision support systems (IDSS) in the field of project management. The peculiarities of information processes in project management greatly complicate or even make it impossible to implement in practice methods for constructing analytical, as well as probabilistic and statistical dependencies between the characteristics of the modeled project management system and the indicators of its internal and external environment. In this regard, as an algorithmic support for IDSS for project management, it is promising to use precedent methods for analyzing information based on knowledge about similar situations previously observed in the practice of project management, and representing knowledge in the form of ontologies. Analysis of practical situations in the field of project management makes it possible to substantiate the expediency of organizing a monitoring procedure for the IDSS knowledge base, based on the results of which decisions on its adaptation are made. The article proposes the main ways of this adaptation: changing the structure and basic elements (first of all, concepts) of ontologies; clarification of the structure of the description of current situations and, therefore, precedents. The developed algorithm for monitoring the IDSS knowledge base on project management for the analysis and identification of typical situations of the feasibility of changing it is described. The algorithm is distinguished by the possibility of developing recommendations on the modification of ontologies based on a fuzzy classification of search results and using precedents relevant to current situations. A procedure is proposed for changing the structure of the description of precedents, taking into account the results of assessing the indices of the fuzzy correspondence of the characteristics of the existing precedents to the characteristics of the project being implemented. A description of a computer program that implements the proposed algorithm and its components, as well as the results of its application are given.

This article considers the urgent scientific and practical task of developing analytical tools to justify the choice and transformation of a business model for an economic organization in a rapidly changing business environment. The mathematical apparatus of cognitive modelling is proposed to use to solve this problem, which makes it possible, based on the analysis of cause- effect relationships between the most significant conditions and factors affecting the economic efficiency and competitiveness of doing business, to improve the reasonableness and reduce the subjectivity of the decisions made by its owners and top managers. An algorithm to justify the choice of a business model for an organization based on the construction and analysis of fuzzy cognitive maps (FCM) of business models is proposed. A common list of business factors (concepts) and a set of causality relations between each pair of concepts has been defined, and a basic FCM of the business model is developed as the basis for constructing FCM models of specific businesses. An example of the application of the developed toolkit in a strategic analysis of the conditions and factors of an organization undertaking the production of furniture, carried out to justify a change in competitive strategy and the associated transformation of the business model, is considered. The analysis has been performed using specialized cognitive modelling software developed at the department of information technologies in economics and management, branch of the National Research University Moscow Power Engineering Institute in Smolensk. The proposed toolkit improves methods and algorithms for intelligent decision-making support in the management of economic and social objects and can find practical application in the strategic management of commercial organizations in various fields, as well as be used by professional consultants in the preparation of recommendations for business model change.

Software engineering

Algorithmic efficiency

The paper presents a method, a mathematical model, and a computer program for the operational diagnostics of an electromechanical system (EMS). During EMS operation, service aging changes the properties of the parametric matrices of the windings and, as a consequence, the characteristics of the EMS vector space. Periodic testing of the vector space offers relevant and reliable data on the current health of the EMS, its changes during operation, and the risk of loss of function. The object of the study is an asynchronous electric motor (AEM). It is urgent to automate the process of assessing the current health of an AEM and to organize the storage of information on its states at different stages of its life cycle. To solve the problem, software (SW) for accumulation of information on AEM operation and for evaluation of its basic performance metrics has been developed in the Python programming language. The SW is based on the topological approach to diagnostics, which implies the analysis of the current responses of motor rotor windings to phase voltage pulses. The SW enables one to determine the rate of the service aging of an item, the probability of its survival and residual life, to obtain access to the history of previous diagnostics, and to visualize the in-service history of the above-mentioned performance metrics. The developed SW can be used to increase the AEM operation efficiency and to plan engineering or repair work; it can also be used as an information source for re- engineering and modification of existing AEMs. The described SW can be extended to perform operational diagnostics based on the topological approach of devices of various types. Also, this SW can be considered as a separate information component of the digital twin of a complex EMS, which will allow us to study the main indicators of its reliability, fault tolerance and operational efficiency at all stages of the life cycle.

The article is devoted to the operation logic modeling of relay protection and automation terminals in order to their verification, adjustment and further exploitation. The problem of adjusting protection terminals mutual interaction is unlikely to appear in real conditions due to wide variety of them. The authors propose a solution to this problem by creating a verified model based on a digital twin of an electric power network section created in the MatLab software package. This model helps to study the functioning of the researched protection settings in nominal, repair, emergency and post-emergency equipment operation modes. A model of the selected substation was created displaying all the properties that are significant for research of the original one. In addition, the requirements analysis for the main and backup protection operation settings of the three-winding transformers was carried out. The main unit is a differential transformer relay protection and the backup one is maximal current protection in amount of three units for every transformer winding circuit: higher, middle and lower transformer voltage branch. The model makes it possible to analyze the relay protection operation selectivity by checking the current settings which could be imported from XML documents unloaded from existing terminals and to evaluate the correctness of new calculated ones with the possibility of their manual input. As a result of the researched object modeling, a three-stage operation analysis of the differential and maximal current protections was carried out. It has shown relay protection selective operation both in the case of nominal and abnormal modes, including the event of the main transformer protection malfunction. This technique can be extended to the other electric power network.

The article considers the information and technical aspects of an innovative autonomous integrated power plant management, including alternative energy sources and a diesel generator set, as well as controlled inverters that provide energy supply to consumers of various priority categories, which can be used in the Arctic regions of the Russian Federation. The main aspects of creating innovative systems are considered and it is determined that the creation of integrated energy systems requires a significant deepening of cooperation between national producers in order to ensure the scalability of integrated energy systems by ensuring the unity of information means of data exchange between individual modules and the control system. It is shown that a specific requirement for control systems of complex power plants is the requirement of high autonomy, including the ability to provide consumers with electricity under variable environmental conditions without direct intervention of operational personnel. The article substantiates the division of the information and algorithmic support of the control system of a complex power plant into two modules – analytical and control. For the analytical module, an algorithm is proposed that ensures the development of control solutions in a complex energy system, ensuring the stability of energy supply to the most important consumers. At the same time, the algorithm provides an increase in the reliability of the energy storage device based on Li-Ion batteries used in the system not only by eliminating excessive charge and deep discharge, but also by reducing the number of charge/discharge cycles. The solution of system autonomy problem is provided by a multivariate algorithm for predicting weather conditions using statistical data and methods for analyzing fuzzy time series. The intelligent control algorithm was implemented in C++, the weather forecasting algorithms were implemented in Python using the ANFIS library.

Information security

Models and methods

The article deals with the mathematical basis and simulation of the saturation processes of current transformers with aperiodic components of short-circuit currents. Saturation processes of current transformers can affect the correct operation of the protections. At power plants, in particular atomic ones, the number of current transformers is several hundred with different loads, lengths of supply cables and the implementation of relay protection. At the same time, the determination of the time to saturation is essential for the construction of circuits and principles of construction of relay protection systems and automation of power plants. The dynamic processes in the primary and secondary circuits of current transformers in dynamics are considered in detail. A mathematical description of the dynamic processes of a current transformer in the nominal mode and during a short circuit in its primary circuit is given. The substantiation of the expediency of using the hypothesis of a rectangular magnetization characteristic in simplified calculations of saturation processes is given. The possibility of using the characteristics of magnetization in the test protocols available in practice in the no-load mode to simulate saturation processes has been demonstrated. Simulation of current transformers for the no-load experiment and power supply of the current transformer from the secondary side, as well as during its operation under conditions of a short circuit on the primary side and a known load on the secondary side is carried out. Thus, with the help of a computer experiment, it is possible to take the current- voltage characteristics and transfer them to the model with the saturation of current transformers already in the short-circuit mode. The efficiency of dynamic simulation of current transformers is shown. The software implementation of the model is performed by means of structural simulation in the MatLab package, based on the solution of equations of matrix structures and emulation of parallel computations. It was found that with the adequacy of the model and the real current transformer with the involvement of information from the no-load mode, the determination of the magnetization time from the aperiodic current components from the model is much easier than the analysis by other existing methods. They require detailed design details of the current transformer and the magnetic properties of the steel.

Models and methods

The article is devoted to the implementation of a method for modeling processes in complex educational systems based on the proposed variety of neuro-fuzzy temporal Petri nets. The article considers educational systems of the level of higher educational institutions, which, of course, belong to the class of complex systems. The need for a method, models and modeling tools is dictated by the fact that modern educational processes require constant modernization, due to the constantly growing volumes of information, changes in legislation, stricter requirements for specialists, rapid development of technologies, constant discoveries in various fields, as well as the influence of external factors. Requirements for the tools for modeling processes in complex systems are formulated, the use of Petri nets as the basis of such models is substantiated. The existing educational processes are considered on the example of the cycle of training in the master's program of the Belarusian-Russian University. The model of educational and information-analytical learning processes in the master's program based on the neuro-fuzzy temporal Petri net is presented. The proposed method allows to increase the flexibility of the choice of individual trajectories of training in the master's program, the effectiveness of elective disciplines and to make the transition to an integrated approach in the preparation of undergraduates. The proposed method can also be used as a basis for monitoring the state and control of information and analytical processes in educational systems. An approach to the construction of software-instrumental environment for the design and modification of information-analytical processes is described, aimed, among other things, at bridging the semantic gap between experts, architects and developers of information-analytical processes. A subsystem for the formation of a neuro-fuzzy temporal model of processes within the framework of a software-instrumental environment is considered.

Processes and systems modeling

The actual problem of an adequate mathematical description of the world development global processes trends is studied on the example of the Earth population growth and the production (consumption) of the electric energy. Various models used to describe the past, present and future of the various processes in nature, technology and economics are considered. It is shown that these processes are well described by the equations obtained during solving differential models with exponentially growth rates decaying in time. These models take into account the currently accepted doctrine of sustainable development of the world system using energy saving technologies, preserving environmental safety and using renewable energy sources. The similarity of the studied global processes and the possibility of their description by one criterion equation are established. At the same time their dynamics is characterized by different speeds. The first period is characterized by a rapid growth. After the inflection point the growth rates slow down but the volumes increase significantly and a gradual saturation occurs. The influence of the model parameters on the character of the studied processes on the phase plane is estimated which significantly simplifies their analysis. It is shown that the process of the world population growth passed the inflection point in 1990 and is 29 years ahead of the world electricity production growth. But the growth rates of electricity production and its consumption per capita are significantly higher. Thus, new mathematical models are proposed to describe the dynamic series of the Earth population growth, world production and electric energy consumption per capita. The obtained mathematical models have been in good agreement with statistical data for 60 years since 1960 and have high values of the determination coefficient. The studied processes prediction for the long-term period up to 2050 was made with their help. The results of the prediction do not contradict the results of other authoritative studies using the global processes inertial development model.

Software engineering

The modern development of information security tools, along with the improvement of remote access methods, allows software and hardware to be audited without the need for direct access to the system under test. One of its components is related to the implementation of software on mobile ARM processor architectures. Within this direction of development, the approach that allows integrating Linux kernel-based distributions by introducing a virtual container chroot (change root) into the Android OS- based system and, consequently, performing penetration testing without the need to use personal computers is highlighted. An example of this approach is the Kali NetHunter distribution which allows remote system administration functionality through the KeX module. Besides the obvious advantages of KeX functionality, some disadvantages should also be mentioned: firstly, the low speed of GUI processing due to translation to remote hosts and the need to support translation at operating system level; secondly, the consumption of energy resources when using the desktop features of the KeX module. In order to solve the mentioned problems, a system of virtualization of energy-efficient container for testing the vulnerabilities of critical information objects has been developed and based on the principle of multi-containerization. The software of the system is represented by two components: an enlarged module for integration of the chroot container into the DeX environment (primary), and an enlarged module for ensuring energy efficiency using predictive neural network models based on variable time intervals (secondary). As a result of comparing the effectiveness of existing and implemented approaches in penetration testing, it is noted that the proposed system can be used in testing the security of particular platforms and systems, including highly sensitive information objects or resources.


Researching of processes and systems

A two-link model of exoskeleton with variable-length links for supporting the lower limbs of the human musculoskeletal system is proposed in the article. The researched model differs from the existing ones by the variable-length links, and by the angle calculation method. While in the existing models, the angles are calculated from the regular direction – from vertical, or from horizontal, – in the proposed research they are calculated between the links. As for practical exoskeleton implementation, the proposed method of angle calculation is appropriate to the actual working conditions of the electrical motors with the reduction gears installed in the hinges, which change the angles between the links. The construction of a variable-length exoskeleton link consists of two absolutely solid weighty sections located at both ends of the link and one weightless section between them in the center of the link. In the weightless section, there is a drive that creates a control longitudinal force, which realizes the increase or decrease in the length of the link in the required manner and provides the necessary maintenance of the length of the link when the person moves in the exoskeleton. The links are connected to each other using spherical hinges. Drives are installed in each hinge, creating control torques, which provide a relative rotational movement of the links. The jointly controlling longitudinal forces and moments realize the maintenance of the posture or the movement of the link in the required manner and, in relation to the exoskeleton, the repetition of the basic biomechanical properties of the human musculoskeletal system. The mathematical model in the form of the system of Lagrange differential equations of the second kind is obtained. The obtained mathematical model is examined for existence and uniqueness of the Cauchy solution. The kinematic trajectory of the link motion has been synthesized, which simulates the anthropomorphic movement of the supporting leg during the single-support phase of movement, and the control actions required for its implementation has been found. The significance of the results obtained in the process of modeling lies in the ability to create active exoskeletons, prostheses in medicine, anthropomorphic robots, and spacesuits that take into account the biomechanical features of the functioning of the human musculoskeletal system.