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№2
Publication date:
16 June 2019
Articles of journal № 2 at 2018 year.
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1. A comparative analysis of methods of calculation the number Pi by standard means [№2 за 2018 год]
Author: O.A. Bakaeva
Visitors: 1633
The process of the research on finding the number Pi can be divided into three periods: the ancient period, the classical era and the era of modern computers. Each of them has its own methods and tools. The purpose of this work is to analyze and compare various methods of calculating the number Pi using standard tools: MS Excel spreadsheet and Free Pascal programming environment. Computational methods are based on mathematical expressions, which are a qualitative approximation of the number Pi. They are the series of Gregory-Leibniz, Madhava, Neelakant, Euler's and Wallis's formulas, etc. The comparative analysis of these expressions and algo-rithms created on their basis has revealed the fastest and exact method of finding thhe number Pi. The paper describes computational studies, the result of which is finding the number Pi accurate within the 10th decimal place. The pur-pose of this study was to determine which computing environment is more accurate and effective for finding the number Pi. Based on the study results, there is a comparative analysis of MS Excel and Free Pascal computational capabilities regarding laboriousness, calculation time and Pi number computing accuracy. The originality of the work is in calculation of the sum of a series that converges to Pi for each new place of summands. Thus, the author shows in practice the dynamics of series convergence to the number Pi. For each of these approximate values of Pi, the absolute and relative errors are calculated. The number of summands is chosen based on calculation accuracy, which is considered satisfactory if the relative error is <0.001%.
2. Finite element structural design in the mathematical package MathCAD [№2 за 2018 год]
Author: Bakushev S.V.
Visitors: 1493
The paper analyses mathematical package MathCAD potential when solving the problems of strength and deformation calculation of building and machine-building constructions using the finite element method. It is shown that MathCAD potentials are definitely not sufficient to solve such problems. It is due to the necessity to process quite a large amount of information. For illustrative and study tasks, when a rigidity matrix has not big dimension and its components can be introduced manually, it is enough to use MathCAD. It can help to solve a problem. In this case, the rigidity matrix should be formed by manual introduction of its component data that were calculated beforehand in MathCAD. In real calculation tasks, a rigidity matrix has a large order (thousands, tens and hundreds of thousands). Therefore, there are specialized software packages to solve them, such as LIRA, SCAD, ANSYS, etc. The paper considers a specific numerical example of calculating a compound profile plate under plain stress condition using the finite element method. The plate is separated into three finite elements. In this case, a rigidity matrix has the order equal to ten; the problem is solved only with manual introduction of its component data.
3. A program of modeling wire temperature and power losses based on operation and atmospheric factors [№2 за 2018 год]
Authors: Balametov A.B., Khalilov E.D., M.P. Bayramov, K.A. Agakhanova
Visitors: 1909
In modern conditions, due to the growth of power consumption and noticeable climatic changes, the interest in calculating admissible mechanical and current loads on the aerial wires has been increased. The maximum use of overhead line capacity can be achieved with reliable information on the line state. The accuracy of calculating electric power losses in overhead power transmission lines might be increased by determining active resistance of wires taking into account the operating current flowing along the lines, the ambient air temperature, wind speed and solar radiation heat. In these conditions, it is very important to have software for evaluating and continuously monitoring wire temperature under various weather conditions, to reliably determine the permissible current load and to be able, if unacceptable line overload occurs, including repair modes, to carry out measures for unloading the remaining work of an aerial line. Modern programs for calculating power systems modes do not include thermal balance equations of aerial lines. This leads to the impossibility of taking into account their temperature conditions due to the mismatch of wire active resistance to their temperature. The authors have developed an algorithm and a program for calculating the specific active resistance of aerial lines wires taking into account the air temperature, working current, wind speed and solar radiation. They also carried out a quantitative assessment of the load current influence, ambient temperature, solar radiation and wind speed on the active resistance of aerial wires. There are the results of calculation of limited current loads for aerial wires. Based on the calculations to evaluate the effect of load current, ambient temperature, solar radiation and wind speed on active resistance of aerial wires, it is established that when calculating power losses for wires without considering the resistance temperature dependence, relative errors can reach 26 % or more, which is not permissible. Therefore, it is required to automatically detect the wire temperature in order to improve the accuracy of the calculation of active power and energy losses.
4. A methodical approach to modeling of complex technical system support with spare parts [№2 за 2018 год]
Authors: D.Yu. Brezhnev, Dopira R.V., A.A. Sudarikov
Visitors: 1307
The article considers a methodical approach to constructing a model of a multilevel system for providing spare parts for complex technical systems. The model is designed to justify a quantitative and nomenclature composition of spare parts kits considering the requirements for efficiency of performance restoration of the equipment samples in the system. The key idea is to put the simulated flow of requests to the model input and to investigate the response of a spare parts system by modeling the time for fulfillment of requests from sets of spare parts, tools of various levels, gradually increasing their nomenclature and quantity composition. At the same time, the simulated stream of requests can be different from the simplest one. It allows reasonable distributing applications for spare parts between sets of spare parts, tools of various levels. The model provides for the possibility of using one of three strategies for replenishment of spare parts kits both in the maintenance system of spare parts and in the specific nomenclature of spare parts in particular. The principle of modular representation of spare parts sets allows modeling a system of providing spare parts in different versions of a single-level or multi-level structure depending on application conditions or the principles of constructing complex technical systems. Modeling takes into account the contribution of each spare part cost to the total cost of the spare parts maintenance system with restriction for the required delay time related spare parts delivery. As a result, it is possible to justify the composition of spare parts kits of a complex technical system in an optimal way.
5. A recommendation system based on data mining of a scientometric research profile [№2 за 2018 год]
Author: Valko D.V.
Visitors: 1907
Nowadays scientific results can be represented in various scientometric bases and systems. They are often popular not because of their relevance, but due to global availability. In fact, scientific results may be out of the scope of a scientific community simply because they are not placed in a popular scientometric system. From scientific point of view, such situation devalues a researcher regardless of quality and relevance of his scientific results. According to the author, the development of recommendations for individual researchers, research teams and their managers at all levels of management would make it possible to pay attention to promising scientific results and reasonably accumulate necessary resources to include such results in popular scientometric systems. Development of tools that operate the big scientometric open data cannot be without data mining methods. The paper shows that based on the algorithm of intellectual analysis of interrelations (like apriori), which is adapted to scientometric data in the Scopus, it is possible to formulate certain sets of associative rules suitable for forecasting probable future scientific results. It is also possible to develop automated recommendations for improving publication activity. The paper proposes the developed methodical tools for analyzing publication and scientometric data using data mining methods. In addition, it describes a modular architecture and a prototype of a software system that allows forming a publication rating and individual recommendations for improving author's publication activity based on scientometric data mining. The paper shows some experimental results on assessing publication potential of researchers affiliated with the South Ural State University. The authors built necessary diagrams in the UML 2.0 notation describing that software system using Microsoft Visio modeling environment.
6. Search of minimal acyclic path in weighted graphs containing negative weight edges [№2 за 2018 год]
Authors: Gdansky N.I., Kulikova N.L., E.V. Chumakova
Visitors: 1301
The paper considers the problem of determining minimal acyclic routes in weighted graphs containing negative weight edges. It also investigates the possibilities of the Bellman-Ford algorithm. It is shown that in general all its possible modifications, even the deepest ones, can determine only approximate solutions. On the average, the best approximate solutions to the problem are given by a modified version of the Bellman-Ford algorithm, in which cycles are discarded when searching for optimal continuations of the desired path. To ensure the search for exact solutions, the authors propose a modification of the branch and boundary method based on using special acyclic search trees. In the nodes of this tree, along with the number of the next vertex, the current cost of the path and the necessary pointers, there are the numbers of all the untraversed vertices, as well as a special list of negative weight edges. A list of vertices is used for acyclic continue of a path. A list of negative weight edges is necessary to estimate the maximum possible decrese of its acyclic continue. The paper suggests to use special bidirectional lists for more convenient practical implementation of acyclic search trees for one level vertices. In such lists, direct links specify the movement to neighboring level nodes. Back references point to the previous vertex in the path from the initial vertex to the given node. The algorithm is described on a C-like pseudocode. There is also an example that demonstrates the approximate character of Bellman-Ford algorithm modifications on the one hand and the work of the proposed method on the other hand.
7. Technology of interaction of IACPaaS cloud platform services with external software [№2 за 2018 год]
Authors: Gribova V.V., F.M. Moskalenko, V.A. Timchenko, Fedorischev L.A.
Visitors: 1858
Modern cloud technologies have a number of advantages over other types of software (simplification of installation, maintenance, access, teamwork, etc.). At the same time, some tasks are impossible to perform on cloud platforms (or non-optimal to perform). Therefore, there is an obvious need in creating standards, interfaces, systems that allow combining capabilities of different software types. This article discusses the architecture and technology of interaction between the cloud platform IACPaaS and external traditional software. The article describes the interaction architecture of the cloud platform and external software, which consists of five main components. Two of the components are on the platform: a service and a proxy agent. The others are on the external system: a web server, a proxy program and external software. The paper describes the features of each component. The authors also present a service development technology taking into account the given architecture. It consists of four main stages: 1) service development on the platform, 2) external software development, 3) web server installation, 4) communication software development – a proxy program. The features of each stage are described. The paper considers the necessary requirements for the development of agents on the platform and the specification of parameters when sending and receiving messages. There are corresponding examples. The paper gives the examples of successful use of the proposed technology when solving transport modeling problems. In the examples, the main computing load is focused on the external software, whereas services for visualizing the results of these calculations are provided on the IACPaaS platform. One example demonstrates the phased implementation of the technology. At the end of the article, there is a discussion of the advantages gained from applying the presented technology.
8. Algorithmic software of software maintenance complex controlling the reliability level of flight facilities [№2 за 2018 год]
Authors: Dopira R.V., V.A. Dikarev, Potapov A.N., E.E. Bueshev, I.A. Yuriev
Visitors: 1339
Improvement of technical means complexes is related to the need for research on extending the life of equipment while reducing operational costs. One of the ways of improving qualitative indicators of a technical condition (TC) of such complexes throughout their life cycle while reducing operational costs is the transition to technical service (TS) with pe-riodical inspection. Nowadays when using automated control systems (management information systems), maintenance methods with periodic monitoring that consider the actual condition of the equipment are becoming more and more popular. It should be noted that none of the methods is implemented without the prevention; each of them has its specificity when determining the timing and amount of preventive maintenance. To solve of the problem of determining rational frequency using statistical projections successfully, the paper proposes algorithmic support for software maintenance complex controlling the level of reliability of flight facilities. In this case, the developers of an algorithm took into account the volume and frequency of maintenance. The developed algorithm is implemented as a software complex, which allows determining optimal periods of maintenance. The algorithm efficiency is verified based on functioning of the automated workplace of a near zone head to control the engineering status of radio facilities. According to the engineering status, the software package determines the optimal maintenance periods for technical means complexes.
9. On the implementation of machine learning tools in real-time intelligent systems [№2 за 2018 год]
Authors: A.P. Eremeev , A.A. Kozhukhov , V.V. Golenkov, N.A. Gulyakina
Visitors: 2029
The paper analyzes the methods of reinforcement learning in terms of using them in real-time intelligent systems (RT IS) on the example of the real-time intelligent decision support systems (RT IDSS). The authors describe implementation of reinforcement learning algorithms based on temporal differences and consider the main advantages of using flexible (anytime) algorithms that can have a significant impact on RT IS efficiency and productivity. Flexible algorithms can be crucial to RT IDSS, as they are able to find acceptable solutions under tight time constraints and improve them (up to optimal ones) while increasing available resources (especially temporary ones). The proposed flexible algorithm includes a statistical forecasting module and a module of multi-agent reinforcement learning. The paper considers the possibilities of implementation of the developed flexible algorithm into a RT IS forecasting subsystem of RT IDSS type to control and monitor a complex technological object. The paper considers the approach to implementation of a transition from knowledge-based intelligent systems training to training of their development tools. At the same time, the architecture of such intelligent systems is considered as the basis for its flexibility and learning capacity. The paper also examines the areas of intelligent system learning and self-learning, as well as their ability to acquire knowledge and skills from different sources. The authors provide rationalization for the application the developed OSTIS technology to develop knowledge-based intelligent systems, including the RT IS.
10. Application of a knowledge representation productional model to assess compliance of an applicant training level to requirements of a position in IT department [№2 за 2018 год]
Authors: Zubkova T.M., L.F. Tagirova, V.K. Tagirov
Visitors: 2152
Nowadays, due to fast development and widespread introduction of information technology in various spheres of life, a large number of specialists in this field (programmers, system administrators, etc.) appeared in the labor market. Therefore, it becomes more difficult for employers to decide on a suitable employee among a large number of potential appli-cants. Besides, employees of recruitment departments have to spend much time to entering and processing applicant data for various positions, including ones in the IT department. The paper describes the solution of the recruitment problem in the IT department based on quality assessments of applicants. There is an algorithm and a software system that allows choosing the most suitable employee for a vacant position using quantitative assessments of professionally significant and personal qualities of applicants. The paper proposes the developed software system to automate the information recruitment processes. It will allow assessing formedness of the required qualities of applicants for a position and store the results in a database for further processing. An expert assessment module was used to support a decision on whether a training level of an applicant met the requirements of a particular IT-department position. The core of this module is a product model of knowledge representation. When the software system is running, applicant information is read from the database and compared with the rules. As a result, the system gives recommendations to a decision maker on a position an applicant can aspire.
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