Кафедри
Постійне посилання на розділhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/35393
Переглянути
8 результатів
Результати пошуку
Документ Evaluation model of the recovery processes of non-markovian systems, considering the elements unreliability under arbitrary distribution laws(Національний технічний університет "Харківський політехнічний інститут", 2022) Raskin, Lev; Ivanchikhin, Yuriy; Sukhomlyn, Larysa; Svyatkin, Iaroslav; Korsun, RomanThe subject of the study is the reliability of recoverable non–Markovian systems, functioning of which is described by arbitrary distribution laws. The purpose of the article is to develop a mathematical model of the functioning of modern computer systems under arbitrary laws of the distribution of stay duration in each of the states, taking into account the recovery system and the provision of spare elements. The main task is to develop an adequate model of the system functioning process, taking into account the non-Markovian character of the processes occurring in the system, its possible large dimension, and the presence of a hierarchical recovery system. Based on this model, a method for calculating the density of the system recovery time distribution has been developed. At the same time, a universal four-parameter distribution is proposed to describe random processes occurring in the system. Using this approximation, the calculation of the desired parameter of the recovery flow is performed by solving the Volterra integral equation with a difference kernel.Документ Analysis of marсovian systems with a given set of selected states(Національний технічний університет "Харківський політехнічний інститут", 2022) Raskin, Lev; Sukhomlyn, Larysa; Korsun, RomanAnalysis of stationary Marcovian systems is traditionally performed using systems of linear Kolmogorov differential equations. Such systems make it possible to determine the probability of the analyzed system being in each of its possible states at an arbitrary time. This standard task becomes more complicated if the set of possible states of systems is heterogeneous and some special subset can be distinguished from it, in accordance with the specifics of the system functioning. Subject of the study is technology development for such systems analysis. In accordance with this, the purpose of the work is to find the distribution law of the random duration of such a system's stay on a set of possible states until it falls into a selected subset of these states. Method for solving the problem is proposed based on splitting the entire set of possible states of the system into two subsets. The first of them contains a selected subset of states, and the second contains all the other states of the system. Now a subset of states is allocated from the second subset, from which a direct transition to the states of the first subset is possible. Next, a system of differential equations describing the transitions between the formed subsets is formed. The solution of this system of equations gives the desired result – distribution of the random duration of the system's stay until the moment of the first hit in the selected subset of states. The method allows solving a large number of practical problems, for example, in the theory of complex systems reliability with many different failure states. In particular, finding the law of the uptime duration distribution, calculating the average duration of uptime.Документ Assessing the informativeness of the controlled parameters in the task of identyfing the state of the system(Національний технічний університет "Харківський політехнічний інститут", 2022) Raskin, Lev Hryhorovych; Sukhomlyn, Larysa Vadymivna; Sokolov, Dmytro Dmytrovych; Domochka, Lidiia VladyslavivnaThe effectiveness of solving the problem of identifying the system state significantly depends on the number of controlled parameters and the degree of their informativeness. The traditional method for assessing the informativeness of these parameters is based on the measure of distance between the probability distributions of the values of the controlled parameter for different states of the system proposed by Kullback. The shortcomings of Kullback measure have been revealed. Firstly, the value of this measure is not normalised and is not limited from above. Secondly, this measure is asymmetric, i.e. its numerical value depends on the way its components enter the calculation ratio. The method for calculating the informativeness criterion proposed in this paper takes into account the uncertainty that arises due to the fuzzy description of the boundaries of the areas of possible values of the controlled parameters for each of the possible states of the system. An important enhancement of the known methods for assessing the informativeness of the controlled parameters is to take into account the real existing inaccuracy in estimating the values of the results of measuring these parameters themselves. These circumstances determine the subject and purpose of the study that is the development of a method for calculating the distance between the distributions of fuzzy values of the controlled parameter, free from the shortcomings of the Kullback measure. To calculate the measure of the distance between the distributions of the values of the controlled parameter under conditions of uncertainty of the initial data, described in terms of fuzzy mathematics, a symmetric criterion is proposed, which is easily calculated. Examples of the criterion calculation are given. The possibilities of increasing the level of informativeness of the criterion using analytical descriptions of membership functions of fuzzy values of the controlled parameter for different states of the system are considered.Документ Semi-Markov reliability models(Національний технічний університет "Харківський політехнічний інститут", 2022) Raskin, Lev; Sviatkin, Iaroslav; Ivanchikhin, Yuriy; Korsun, RomanTraditional technologies for reliability analysis of semi-Markov systems are limited to obtaining a stationary state probability distribution. However, when solving practical control problems in such systems, the study of transient processes is of considerable interest. This implies the subject of research - the analysis of the laws of distribution of the system states probabilities. The goal of the work is to obtain the desired distribution at any time. The complexity of the problem solving is determined by the need to obtain a result for arbitrary distribution laws of the duration of the system's stay in each state before leaving. An easy-to-implement method for the analysis of semi-Markov reliability models has been suggested. The method is based on the possibility of approximating probability-theoretic descriptions of failure and recovery flows in the system using the Erlang distribution laws of the proper order. The developed computational scheme uses the most important property of Erlang flows, which are formed as a result of sieving the simplest Poisson flow. In this case, the semi-Markov model is reduced to the Markov one, which radically simplifies the analysis of real systems.Документ Analysis of multi-threaded markov systems(Національний технічний університет "Харківський політехнічний інститут", 2021) Raskin, Lev; Sukhomlyn, Larysa; Sagaidachny, Dmytro; Korsun, RomanKnown technologies for analyzing Markov systems use a well-operating mathematical apparatus based on the computational implementation of the fundamental Markov property. Herewith the resulting systems of linear algebraic equations are easily solved numerically. Moreover, when solving lots of practical problems, this numerical solution is insufficient. For instance, both in problems of structural and parametric synthesis of systems, as well as in control problems. These problems require to obtain analytical relations describing the dependences of probability values of states of the analyzed system with the numerical values of its parameters. The complexity of the analytical solution of the related systems of linear algebraic equations increases rapidly along with the increase in the system dimensionality. This very phenomenon manifests itself especially demonstratively when analyzing multi-threaded queuing systems. Accordingly, the objective of this paper is to develop an effective computational method for obtaining analytical relations that allow to analyze high-dimensional Markov systems. To analyze such systems this paper provides for a decomposition method based on the idea of phase enlargement of system states. The proposed and substantiated method allows to obtain analytical relations for calculating the distribution of Markov system states. The method can be effectively applied to solve problems of analysis and management in high-dimensional Markov systems. An example has been considered.Документ Structural optimization in a multi-channel distributed mass service system(Національний технічний університет "Харківський політехнічний інститут", 2021) Raskin, Lev; Sira, Oksana; Parfeniuk, Yurii; Sukhomlyn, LarysaProblem of structural optimization in a distributed service system is solved by the example of system "Production - delivery - consumption" for mass market product. In this regard, the purpose of work is to develop a method for structural optimization of "Production - delivery - mass consumption" system, by introducing and rational placement of intermediate production points based on solving clustering problems with taking into account the peculiarities of calculating distances between city objects. To achieve the goal of the work, it is necessary to solve the following tasks: clustering of city objects, using the metric of city blocks, for a given number of groups for selected location of production and grouping centers; finding the best location for a given number of clustering centers; determination of a rational number of clustering centers. Task was solved in three stages. First stage - clustering a set of consumption objects for given intermediate delivery centers locations. The second stage - finding the best locations for a given number of intermediate delivery centers. The third stage - determination of the rational number of intermediate centers. Formulated problem is solved according to two criteria: combined length of delivery routes product consumers and the probability that a random delivery time exceeds the critical value. The numerical value of the second criterion is calculated on the assumption that for each path may be estimated value of the mean and variance delivery time. The appropriate number of production centers is determined by a simple comparison of system efficiency for several realistically possible options. An example of clustering problem solving in the metric of "city blocks" on a directed graph by both criteria is given.Документ Selection of the optimum route in an extended transportation network under uncertainty(Національний технічний університет "Харківський політехнічний інститут", 2021) Raskin, Lev; Sira, Oksana; Parfeniuk, YuriiRelevance. For a given values set of extensive transport network sections lengths an exact method has been developed for finding optimal routes. The method provides an approximate solution when the initial data - are random variables with known distribution laws, as well as if these data are not clearly specified. Fora special case with a normal distribution of the numerical characteristics of the network, solution is brought to the final results. Method. An exact method of deterministic routing is proposed, which gives an approximate solution in case of random initial data. The method is extended to the case when the initial data are described in theory of fuzzy sets terms. The problem of stability assessing of solutions to problems of control the theory under conditions of uncertainty of initial data is considered. Results. A method of optimal routes finding is proposed when the initial data are deterministic or random variables with known distribution densities. A particular case of a probabilistic -theoretical description of the initial data is considered when can be obtained a simple solution of problem. Proposed method for obtaining an approximate solution in the general case for arbitrary distribution densities of random initial data. The situation is common when the initial data are not clearly defined. A simple computational procedure proposed for obtaining a solution. A method for stability assessing of solutions to control problems adopted under conditions of uncertainty in the initial data, is considered.Документ Метод поэлементной многокритериальной композиции оптимальных маршрутов в транспортных сетях(НТУ "ХПІ", 2018) Раскин, Лев Григорьевич; Серая, Оксана Владимировна; Парфенюк, Юрий ЛеонидовичПредложен простой метод отыскания оптимальных маршрутов в транспортной задаче линейного программирования. Задача решена с использованием совокупности критериев: средняя суммарная стоимость транспортировок, продолжительность и надежность выполнения плана. Модель задачи – ориентированный граф. Вершинам графа соответствуют промежуточные пункты на множестве магистралей, соединяющих пункты производства и потребления. Дуги, соединяющие вершины графа, размечены числами, задающими среднюю стоимость транспортировки единицы продукта через участок маршрута, соответствующей дуге, среднюю продолжительность транспортировки вдоль этого участка и вероятность его преодоления. Для решения задачи предложена мера эффективности использования участков, обладающая свойством аддитивности, то есть мера результата объединения двух участков равна сумме мер этих участков. Мера учитывает значения для всех трех критериев. Описана вычислительная процедура, реализующая метод, которая не требует комбинаторного перебора вариантов и обеспечивает возможность быстрого получения компромиссного результата. Процедура основана на использовании предложенной специальной операции коммутации матриц. Эта операция обеспечивает возможность расчета меры эффективности всех возможных двухшаговых, затем трехшаговых и далее k-шаговых путей. Операция итерационно продолжается до тех пор, пока не будет найдена мера маршрута, соединяющая начальный пункт с конечным. Важным дополнительным достоинством метода является возможность его использования для отыскания эффективных маршрутов в сложных транспортных сетях с большим числом промежуточных пунктов. При этом, если переход от одного из пунктов в другой может быть осуществлен через какой-либо промежуточный пункт из некоторого их множества, то метод позволяет найти наилучший из возможных маршрутов. Рассмотрены примеры решения задачи для разных формулировок многокритериальной транспортной задачи.