Failure Rate Of Unit Research Articles

Mathematical Techniques for Computing the Reliability of a Parallel-series System of Order (2,3,1) under Rayleigh Failure Laws

Some well-known mathematical techniques have been used to compute the reliability of a parallel-series system of order (2,3,1). The system is composed of four units labelled as A, B, C and D. The configuration involves two parallel subsystems: the first containing units A, B and C arranged in series and the second comprising a single unit D. The failure rate of units is assumed to follow the Rayleigh distribution. With the use of the decomposition method, cut set method and event space method, expressions for both reliability and Mean Time to System Failure (MTSF) have been derived. By considering all units to be identical, the reliability measures have been obtained numerically for specific parameter values. The trends of these measures have been represented graphically to understand the effect of parameters. The study has its practical significance in assessing the reliability of solar panel system. . KEYWORDS :Parallel-series System, Rayleigh failure laws, Decomposition method, Cut set method, Event space method.

Analyzing the Reliability of a Pumping System through the Application of Copula Analysis

This paper derives and evaluates the reliability measures for a model pumping system composed of six subsystems linked in series: subsystems 1, 2, and 6, each comprising one unit, while subsystems 3 and 5 each contain three units operating in parallel. Subsystem 4 contains three units effectively operating in series. Unit failure rates are assumed to be constant, while repair rates are modeled by either a general distribution or, in the event of system failure, a Gumbel–Hougaard copula. The Laplace transform and additional supplementary variable approaches are employed to solve the system. The conventional measures of reliability are computed for a range of parameter values and as functions of time. In addition, tables are presented containing parameters for different cases, accompanied by a discussion of how they were chosen and their impact on the results.

Reliability, Availability, Maintainability, and Dependability Analysis of Cold Standby Series-Parallel System

This paper dealt with the evaluation reliability, availability, maintainability, dependability, mean time between failures, and mean time to failure of series-parallel system. The system under investigation has four subsystems, namely subsystem A containing two units in cold standby, subsystem B and C possess one unit each, and subsystem D has two units in cold standby. Through the transition diagram of each subsystem and the Markov birth–death process, Chapman Kolmogorov forward equations are derived. Both failure and repair rates of units in each subsystem are assumed to follow exponential distribution. The objective is to derive the corresponding reliability models of dependability, availability, maintainability, and reliability and capture the effect of system parameters on reliability, availability, maintainability, and dependability and to determine the critical subsystems. On the basis of numerical results obtained, the system’s performance has been evaluated. Moreover, the outcome of this study shows that the ideal system reliability can be achieved when the overall system failure rate is low and the supporting units are activated.

Preventive maintenance and silica exposure limits integrated in the production planning of a granite processing unit

PurposeThis paper studies the integration of production and maintenance planning for an unreliable production system subject to gradual deterioration. The goal of this planning is to optimize production and maintenance while reducing workers' exposure to silica dust. The objective will therefore be to offer manufacturers a production strategy that minimizes the total cost of production while considering the health of employees.Design/methodology/approachAdequate prevention methods are determined and integrated into the granite transformation production system, which evolves in a stochastic environment. With the failure rate of the dust reduction unit being a function of its degradation state, the authors solve the optimization problem using stochastic dynamic programming in the context of nonhomogeneous Markov chain.FindingsThe resulting planning strategy shows that one can manage stock optimally while ensuring a healthy environment for workers. It ensures that crystalline silica prevention equipment is available and effective and defines the production rate according to a critical threshold, which is a function of the age of the dust reduction unit.Research limitations/implicationsThis article illustrates that it is possible to integrate silica dust reduction measures into production planning while remaining optimal and ensuring the health of operators. In the present study, the machined granite was assumed to be a natural granite, and production takes place in a closed environment.Originality/valueThe originality of this work lies in its development of an optimal joint production and maintenance strategy, which considers limits of exposure to crystalline silica. An optimal production and maintenance control policy considering employees' health is therefore proposed.

An Investigation on the Impacts of Low Probability and High Intensity Events on Wind Power Generator’s Market Participation

This paper presents an extensive decision-making model for Wind Power Generators (WPGs) for profit maximization in an electricity market environment. This model has been presented at the intraday market stage due to the fact that WPGs can react according to the latest information and also they have less forecast errors in comparison to Day-ahead (DA) market. In addition, the Intraday Demand Response Exchange (IDRX) market is modelled with the aim of covering wind generation volatility so that the WPG can participate in it as a buyer. Note that, Demand Response (DR) uncertainty is modelled through Information Gap Decision Theory (IGDT) method so that the amount of financial resistance to the possible increase of the load is considered. In this article, the profitability of WPG in the event of High-Intensity and Low-Probability (HILP) events such as the hurricane, is also examined. In fact, the effects of hurricane on failure rate, reliability and aging of wind units are investigated. The Conditional Value at Risk (CVaR) is utilized to quantify the WPG risk as well. Several numerical analysis are conducted to show evidence of the approach efficacy.

Reliability analysis of a complex repairable system in series configuration with switch and catastrophic failure using copula repair

This paper describes an analytical framework for in-depth investigation of a complex system consisting of two subsystems (namely L and M) in series configuration. Subsystem-L is composed of three identical units in parallel configuration that are working under 1-out-of-3: G policy, while subsystem-M has two non-identical units that are working under 1-out-of-2: G: policy. In subsystem-M, priority in operation is given to M1 unit whereas M2 unit put into cold standby mode if not in use. Moreover, both the subsystems are connected with controllers that may be perfect or imperfect at the time of need. We have considered a catastrophic failure due to frequent change in environmental conditions or man-made disruption. Failure rates of units in both the subsystems are constant and assumed to follow exponential distribution, but their repair supports two types of distributions namely general distribution and Gumbel-Hougaard family copula distribution. The system is studied by using the supplementary variable technique, Laplace transformation and Gumbel-Hougaard family of copula to derive differential equations and obtain important reliability indexes such as availability of the system, reliability of the system and profit analysis. The results have shown by tables and graphs. Conclusive part have been discussed in the last section of this study.

Reliability analysis of station autonomous computer system based on fuzzy dynamic fault tree and Markov model

AbstractStation autonomous computer system is the core of the centralized traffic control (CTC) system. The working mode is dual computer hot standby, and its reliability is very important. Due to the dynamic and fuzzy issue with the reliability analysis of station autonomous computer system, a reliability analysis method is formulated based on fuzzy dynamic fault tree (DFT) and Markov model. First, the structure and working principle of the dual computer hot standby autonomous computer system and the double 2‐vote‐2 autonomous computer system are analyzed, and two autonomous computer systems based on DFT are formulated. Then, the failure rates and the fault detection probabilities are considered as fuzzy variables and represented as triangular fuzzy variables. The fuzzy state transition matrix of the system is obtained by conversion of DFT to the Markov model. Finally, the fuzzy reliability of the system is calculated by Laplace transform. Simulation results show that the reliability of the dual computer hot standby autonomous computer system is higher than that of the double 2‐vote‐2 autonomous computer system. Besides, the reliability of the hardware system is not only related to the structure of the system, but also affected by the uncertain unit failure rate, fault detection probabilities, and so on.

Reliability analysis of a complex repairable system in series configuration with switch and catastrophic failure using copula repair

This paper describes an analytical framework for in-depth investigation of a complex system consisting of two subsystems (namely L and M) in series configuration. Subsystem-L is composed of three identical units in parallel configuration that are working under 1-out-of-3: G policy, while subsystem-M has two non-identical units that are working under 1-out-of-2: G: policy. In subsystem-M, priority in operation is given to M1 unit whereas M2 unit put into cold standby mode if not in use. Moreover, both the subsystems are connected with controllers that may be perfect or imperfect at the time of need. We have considered a catastrophic failure due to frequent change in environmental conditions or man-made disruption. Failure rates of units in both the subsystems are constant and assumed to follow exponential distribution, but their repair supports two types of distributions namely general distribution and Gumbel-Hougaard family copula distribution. The system is studied by using the supplementary variable technique, Laplace transformation and Gumbel-Hougaard family of copula to derive differential equations and obtain important reliability indexes such as availability of the system, reliability of the system and profit analysis. The results have shown by tables and graphs. Conclusive part have been discussed in the last section of this study.

ПРИМЕНЕНИЕ МОДЕЛЕЙ НА СЕТЯХ ПЕТРИ ПРИ ОРГАНИЗАЦИИ ТЕХНИЧЕСКОГО ОБСЛУЖИВАНИЯ АВТОНОМНЫХ АГРОТЕХНИЧЕСКИХ ТРАНСПОРТНЫХ СРЕДСТВ

A complex of simulation models was developed to study the processes of repair and maintenance of the system of autonomous agricultural vehicles. The general structure of the diagnostic system for robotic agricultural vehicles was presented. The hierarchical structure of simulation models for a robotic vehicle was described. A temporary colored Petri net model was proposed. The model makes it possible to evaluate the effectiveness of predictive maintenance for a given failure rate of vehicle units and aggregates. A formal description of an autonomous vehicle was developed in the form of the primary parameter multisets. The experimental results of the simulation modelling confirmed the model adequacy. The results are applied to study the work of an autonomous vehicle group in agricultural fields under difficult operating conditions.

Cost Benefit Analysis of a k-out-of-n: G Type Warm Standby Series System Under Catastrophic Failure Using Copula Linguistics

This paper deals with the study of reliability measures of a complex engineering system consisting three subsystems namely L, M, and N in series configuration. The subsystem-L has three units working under 1-out-of-3: G; policy, the subsystem-M has two units working under 1-out-of-2: G policy and the subsystem-N has one unit working under 1-out-of-1: G; policy. Moreover, the system may face catastrophic failure at any time t. The failure rates of units of all subsystems are constant and assumed to follow the exponential distribution however, their repair supports two types of distribution namely general distribution and Gumbel-Hougaard family copula distribution. The system is analyzed by using the supplementary variable technique, Laplace transformation and Gumbel-Hougaard family of copula to derive the differential equations and to obtain important reliability characteristics such as availability of the system, reliability of the system, MTTF, and profit analysis. The numerical results for reliability, availability, MTTF, and profit function are obtained by taking particular values of various parameters and repair cost using maple. Tables and figures demonstrate the computed results and conclude that copula repair is more effective repair policy for better performance of repairable systems. It gives a new aspect to scientific community to adopt multi-dimension repair in form of copula. Furthermore, the results of the model are beneficial for system engineers and designers, reliability and maintenance managers.

ВИБУДОВУВАННЯ ЧАСОВОЇ ПРЯМОЇ ЖИТТЄВОГО ЦИКЛУ ЗРАЗКА ТАНКА Т-64Б ТА ВИЗНАЧЕННЯ ОПТИМАЛЬНОЇ ПЕРІОДИЧНОСТІ ЙОГО ТЕХНІЧНОГО ОБСЛУГОВУВАННЯ

Предметом вивчення в статті є життєвий цикл зразка танка Т-64Б. Метою дослідження є визначення оптимальної періодичності технічного обслуговування зразка танка Т-64Б, його складальних одиниць та систем. Задачі: визначити закон надійності та аналітичні залежності між ймовірністю безвідмовної роботи та інтенсивністю відмов окремих складальних одиниць та систем танків Т-64Б; проаналізувати середнє напрацювання на відмову окремих складальних одиниць та систем танків Т-64Б, які експлуатувалися в навчально-бойовій групі у період від нормальної експлуатації до старіння і капітального ремонту; провести коригування термінів чергового технічного обслуговування; вибудувати часову пряму життєвого циклу зразка Т-64Б на основі оптимізації циклу технічного обслуговування і ремонту. Методологічною основою дослідження стали загальнонаукові та спеціальні методи наукового пізнання. Отримані такі результати. Були досліджені статистичні дані наробітки на відмову складальних одиниць та систем танків Т-64Б, які експлуатувалися в навчально-бойовій групі у період від нормальної експлуатації до капітального ремонту. За результатами дослідження обраховані оптимальні строки технічного обслуговування систем зразка танку Т-64Б до капітального ремонту. Пропонуємий цикл технічних обслуговувань зразка Т-64Б протягом його життєвого циклу сприятиме збільшенню загального часу експлуатації зразка Т-64Б збільшився на 4% за період від початку нормальної експлуатації до технічного обслуговування -2. Висновки. Термін чергового технічного обслуговування може бути визначений як інтервал часу знаходження об'єкта в працездатному стані із заданою ймовірністю. Ймовірності часу напрацювання до відмови вузлів та систем зразка танка Т-64Б у період життєвого циклу до капітального ремонту є випадковою величиною, яка підкорена закону Вейбулла, при наближенні його до експоненціального закону у період нормальної експлуатації до старіння і капітального ремонту. Аналітичні залежності між імовірністю безвідмовної роботи і інтенсивністю відмов дають змогу визначити оптимальні строки технічного обслуговування систем зразка танку Т-64Б до капітального ремонту та необхіднодостатній час експлуатації машини при заданій надійності. Вибудування часової прямої життєвого циклу зразка техніки на основі оптимізації циклу технічного обслуговування і ремонту сприятиме підтриманню на нормативному рівні показників експлуатаційної надійності протягом всього його життєвого циклу з одночасним скороченням матеріальних, трудових та фінансових витрат

Performance analysis of a complex repairable system with two subsystems in series configuration with an imperfect switch

This paper presents the study of reliability measures of a complex system consisting of two subsystems, subsystem-1, and subsystem-2, in a series configuration with switching device. The subsystem-1 has five units that are working under 2-out-of-5: G policy and the subsystem-2 has two units that are working under 1-out-of-2: G policy. Moreover, the switching device in the system is unreliable, and as long as the switch fails, the whole system fails immediately. Failure rates of units of subsystems are constant and assumed to follow the exponential distribution. Still, their repair supports two types of distribution, namely general distribution and Gumbel-Hougaard family copula distribution. Using the supplementary variable technique, Laplace transformations, and copula approach differential equations developed. Important reliability characteristics such as availability of the system, reliability of the system, MTTF, profit analysis, and sensitivity analysis for MTTF have computed for fixed values of failure and repair rates. Particular cases corresponding to the switching device have also considered. Graphs demonstrate results, and consequently, conclusions have done.

Safety Risk Management in Production Process: A case study in the automotive supplier industry

This paper deals with the study of reliability measures of a complex engineering system consisting three subsystems namely L, M, and N in series configuration. The subsystem-L has three units working under 1-out-of-3: G; policy, the subsystem-M has two units working under 1-out-of-2: G policy and the subsystem-N has one unit working under 1-out-of-1: G; policy. Moreover, the system may face catastrophic failure at any time t. The failure rates of units of all subsystems are constant and assumed to follow the exponential distribution however, their repair supports two types of distribution namely general distribution and Gumbel-Hougaard family copula distribution. The system is analyzed by using the supplementary variable technique, Laplace transformation and Gumbel-Hougaard family of copula to derive the differential equations and to obtain important reliability characteristics such as availability of the system, reliability of the system, MTTF, and profit analysis. The numerical results for reliability, availability, MTTF, and profit function are obtained by taking particular values of various parameters and repair cost using maple. Tables and figures demonstrate the computed results and conclude that copula repair is more effective repair policy for better performance of repairable systems. It gives a new aspect to scientific community to adopt multi-dimension repair in form of copula. Furthermore, the results of the model are beneficial for system engineers and designers, reliability and maintenance managers.

Reliability Evaluation in Microgrids With Non-Exponential Failure Rates of Power Units

This article explores the impacts of non-exponentially distributed failures on reliability of microgrids. Failure rate of some components such as power electronic converters is not constant, while they play a major role in microgrids. Consequently, their failure characteristics will affect the microgrid reliability. Hence, the conventional reliability evaluation approaches based on mean time to failure may introduce inaccurate inputs for decision making in planning and operation of microgrids. In this article, different approaches are employed for evaluating the reliability of microgrids with non-constant failure rates. The obtained results indicate that the system reliability remarkably depends on the failure characteristics and considering mean or steady-state probabilities instead of failure statistics may introduce erroneous reliability prediction results. Numerical case studies are provided to illustrate the impacts of failure characteristics on the availability of single power units as well as the reliability of microgrids.

Performance assessment of repairable system in series configuration under different types of failure and repair policies using copula linguistics

This paper deals with the study of reliability measures of a complex system consisting two subsystems, subsystem-1 and subsystem-2 in a series configuration. The subsystem-1 has three units that are working under the policy 2-out-of-3: F; policy, and the subsystem-2 has two units that are working under 1-out-of-2: G; policy. Failure rates of units of subsystems are constant and assumed to follow an exponential distribution, but their repair supports two types of distribution, general distribution, and Gumbel-Hougaard family copula distribution. Two types of repair (general repair and copula repair) have been employed for partially failed and completely failed states. The system is analysed using the supplementary variable technique. Some important measures of reliability such as availability of system, reliability of the system, MTTF and profit analysis have been discussed. Computations have taken a particular case by evaluating availability, reliability, MTTF and profit of operation of the system.

Availability evaluation of repairable system requiring two types of supporting device for operations

With advancement of modern science and technology, complex systems connected to an external supporting device for their operations have been manufactured to meet the demand of industries, economic growth and populace in general. Companies and organizations heavily rely on these systems to conduct their business. This study presents the availability assessment of a single unit system connected to two types of an external supporting device for its operation. Each type of supporting device has two copies I and II. First order differential equations method is used to obtain the explicit expression for the steady-state availability. Based on assumed numerical values given to system parameters, graphical illustrations are given to highlight important results. Comparisons are performed to highlight the impact of unit failure and repair rates.

Performance Analysis of a Stochastic System with Standby Failure and Maintenance

industrial systems some components are kept in spare to cope up with the failures of operating components. The failure of these spares too, significantly affects the functioning and outputs of the system. The current paper investigates a semi- Markov model for a redundant system consisting of two identical units and a repair facility. The system starts operating with one unit in operation and remaining in redundancy mode. The failure rate of unit in redundancy is zero, initially. After crossing a pre specified time the redundant unit is expected to fail and thereafter it goes under inspection to check feasibility of maintenance or replacement so that necessary remedial action can be taken. Under this framework the expressions for various measures of system performance are derived exploring the regenerative point technique of renewal theory. A numerical example, for a particular case, illustrates the practical importance of the study graphically.

Intelligent stochastic framework to solve the reconfiguration problem from the reliability view

This study proposes a new method to employ the distribution feeder reconfiguration as a reinforcement strategy to enhance the reliability of the distribution systems. Also, several wind power sources are considered to assess their effects on the reliability indices. In order to make the final results more dependable, a stochastic framework based on the probabilistic power flow is utilised to consider the uncertainty of forecast/measurement error of the active and reactive loads, failure rate, repair rate and output generation of wind units, concurrently. The objective functions to be investigated are (i) system average interruption frequency index, (ii) average energy not supplied, (iii) active power losses and (iv) total cost. Moreover, a new modified optimisation method based on harmony search algorithm is proposed to improve the total ability of the algorithm to explore the problem search space globally. The effectiveness and efficiency of the proposed method are examined through two radial distribution test systems.

Assessment of Spare Breaker Requirements for High Voltage Transmission Stations

This paper describes a probabilistic method based on a total risk index (probability times consequences) for assessing the number of spare breakers required for a group of similar high voltage breakers used in switching and transformer stations. The proposed method uses a Markov model for assessing the probability of failures and a bulk power system reliability program for evaluating failure consequences. The method considers a number of factors such as the group size, unit failure rate, unit repair time, transmission station layout, and other power system parameters that may impact the number of spare breakers. A cost/benefit analysis approach is used in determining the required number of spare breakers. The number of spare units is determined when the total cost (sum of spare unit costs, system operating costs and system outage costs due to breaker failures) is minimum. An example is given to illustrate the proposed method of assessment.

Extended optimal replacement policy for a two-unit system with failure rate interaction and external shocks

This study presents an extended replacement policy for a two-unit system which is subjected to shocks and exhibits failure rate from interaction. The external shocks that affect the system are of two types. A type I shock causes a minor failure of unit-A and the damage that is caused by such a failure affects unit-B, whereas a type II shock causes a total failure of the system (catastrophic failure). All unit-A failures can be recovered by making minimal repairs. The system also exhibits the interaction between the failure rates of units: a failure of any unit-A causes an internal shock that increases the failure rate of unit-B, whereas a failure of a unit-B causes instantaneous failure of unit-A. The goal of this study is to derive the long-run cost per unit time of replacement by introducing relative costs as a factor in determining optimality; then, the optimal replacement period, T*, and the optimal number of unit-A failures, n*, which minimise that cost can be determined. A numerical example illustrates the method.