基于成本优先级的部件维修策略分析

现实中,系统由于任务、环境等因素,无法实时对故障部件进行维修。因此需要在任务间隔期间或对故障部件进行维修的同时对系统各部件进行预防性机会维修。本文考虑系统期望维修成本,提出了基于部件维修优先级的预防性维修策略。首先把系统期望维修成本分为失效部件维修成本、失效部件导致系统故障的成本和预防性维修其他部件的成本,提出了基于成本的二态和多态系统部件维修优先级度量方法,并在两种场景下分析了如何选择预防性维修部件。其次针对多态系统,研究了基于成本重要度的部件最佳维修水平,并讨论了成本约束下的部件预防性维修策略。最后以某型预警机系统为例进行验证,结果表明,基于成本的预防性维修策略不仅与故障部件位置和相关成本有关,而且还与可用于预防性维修的其他部件重要性有关。     

基于综合重要度的动车组多部件系统机会维修策略研究

针对我国动车组列车现行维修方式,提出基于综合重要度序列的动车组多部件系统机会维修策略,对提高系统可靠度贡献大的关键部件进行准时优先维修。建立部件综合重要度指数计算模型,并依据其对部件维修优先级进行排序。以维修总成本最低为目标计算单部件最优维修周期及时刻,以系统维修总成本最低为目标,以关键部件的维修时刻为系统停机时刻建立考虑重要度的多部件系统机会维修模型。算例选取某型动车组四级修时更换的四部件系统为研究对象,讨论机会维修里程窗的大小及其偏移量对维修效果的影响,对比结果表明,考虑综合重要度的机会维修策略能够在维修费用基本持平的条件下,保证对系统可靠性贡献大的关键部件的可靠性,进而保证系统的整体可靠性。     

具有使用及维修优先权的三部件冷贮备系统的几何模型

研究了两个不同型部件串联带有一个冷贮备部件的可修型冷贮备系统.假定三个部件的工作时间和维修时间均服从指数分布,对部件2的修理是几何维修而对部件1和3的修理则是修复如新,且部件2比部件3有优先使用权和优先维修权.在这些假设下,运用补充变量法与几何过程理论,得出了系统可靠度,首次故障前平均时间,可用度,瞬时故障频度和修理工空闲的概率等可靠性指标.     

基于可靠性指标的冷贮备可修系统与单部件可修系统关系分析

讨论冷贮备可修系统与单部件可修系统在可靠性指标方面的关系,具有理论价值和实际意义.首先讨论由两部件组成的冷贮备可修系统与单部件可修系统的关系,假设冷贮备可修系统的每个部件的工作寿命都服从一般分布,部件故障后的修理时间服从指数分布,得到在稳态可用度、稳态故障频度、瞬时可用度和瞬时故障频度等指标方面冷贮备可修系统等价于相应的单部件可修系统,推导了若干个定理和推论,给出了相应结论;然后探讨带有冷贮备的多部件串联系统在求解可靠性指标时转化为相应单部件系统的思路:将带有一个冷贮备的多部件串联可修系统等价为一般的串联系统,进一步等价单部件可修系统.为工程上广泛存在的带有冷贮备的多部件系统的可靠性指标计算提供基础及相应公式.     

自保护相依多部件系统的预防维修建模及策略优化

自保护技术作为自愈技术的一种,能够使系统在环境或工况条件变化的干扰下以较高可靠性运行。本文构建了一个新的具有相依主要部件和辅助部件的系统可靠性模型,其中主要部件的退化速率与工作中的辅助部件的数量有关。此外,基于定期检测和预防维修策略,本文利用半再生过程技术求解了系统的长期运行平均成本,并以长期运行平均成本最小化为目标给出了系统的最优预防维修策略。最后,以镗刀系统为例,利用所提方法给出了预防更换阈值和检测周期的最优值,以期望为实际维修行为决策提供理论参考。     

多态系统部件维修成本评估分析

多态系统是可靠性理论中的一种重要系统,是指部件和系统具有多个状态。随着部件的劣化,系统的性能随之下降。为了提高系统的性能,部件需要进行一定的维修。本文考虑部件状态转移率与停留时间的关系,利用重要度理论来分析部件维修成本的变化规律,得出对系统维修成本影响最大的部件。首先,基于维修成本的函数关系,给出了重要度的表达式;其次,针对典型串联系统和并联系统,随着时间推移,给出维修成本的变化规律;最后算例仿真验证了提出方法的有效性和正确性。     

泊松冲击下单部件混合贮备系统可靠性分析

研究的是泊松冲击下由三同型部件组成的单部件混合贮备系统可靠性.在系统三部件分别为工作部件、温贮备部件和冷贮备部件假定下,且假定三部件在工作过程中都是接着工作、修理、冷贮备、温贮备、工作依次进行状态转移,同时假设部件寿命和维修时间都服从指数分布,利用基本概率理论和马尔可夫过程理论分别对不可修和可修两类系统进行讨论得到相关可靠性指标.     

基于休假时间和基准可靠度的冷贮备二维预防维修策略

研究由两个不同型部件和一个修理工组成的冷贮备可修系统,其中部件1具有优先使用权.为了延长系统的工作时间,考虑对部件1进行非定期预防维修和故障维修相结合的维修策略,并以部件1的故障次数N和预防维修间隔T为二元维修策略(N,T),利用几何过程和更新过程等数学理论,建立以修理工单位时间内平均休假时间为目标函数、以费用率和平均停机时间为约束条件的优化模型,最后运用实例验证了模型的有效性.     

有两种故障状态的两部件串联系统的预防维修策略

本文研究的是由两个部件串联组成且有两种故障状态的系统的预防维修策略, 当系统的工作时间达到T时进行预防维修, 预防维修使部件恢复到上一次故障维修后的状态。每个部件发生故障都有两种状态, 可维修和不可维修。当部件的故障为可维修故障时, 修理工对其进行故障维修, 且每次故障维修后的工作时间形成随机递减的几何过程, 每次故障后的维修时间形成随机递增的几何过程。当部件发生N次可维修故障或一次不可维修故障时进行更换。以部件进行预防维修的间隔和更换前的可维修故障次数N组成的二维策略(T, N) 为策略, 利用更新过程和几何过程理论求出了系统经长期运行单位时间内期望费用的表达式, 并给出了具体例子和数值分析。     

机会维修策略下的系统可用度分析

机会维修是针对多部件系统提出的一类新的维修策略,主要解决部件间存在经济相关性的问题.利用更新过程理论建立了机会维修策略下的系统模型,并给出了系统瞬态和稳态可用度的求解方法.通过分析比较可知,利用更新过程稳态下的某些特性,可以不必求解更新方程而比较简便地求解系统稳态可用度.     

An optimal repair–replacement policy for a cold standby system with use priority

In this paper, the maintenance problem for a cold standby system consisting of two dissimilar components and one repairman is studied. Assume that both component 1 and component 2 after repair follow geometric process repair and component 1 is given priority in use when both components are workable. Under these assumptions, using geometric process repair model, we consider a replacement policy N under which the system is replaced when the number of failures of component 1 reaches N. Our purpose is to determine an optimal replacement policy N1 such that the average cost rate (i.e. the long-run average cost per unit time) of the system is minimized. The explicit expression for the average cost rate of the system is derived and the corresponding optimal replacement policy N1 can be determined analytically or numerically. Finally, a numerical example is given to illustrate some theoretical results and the model applicability.     

Optimal maintenance policy in a multistate deteriorating standby system

An optimal maintenance policy for a multistate deteriorating standby system is proposed in this study. Traditionally, a system could only presume two operational states: success or failure, and the maintenance policy is to determine the optimal number of standby components, subject to factors such as maintenance capability, cost of the standby items, etc., so as to minimize the operational cost. This study considers a more general production system in which progressive deterioration is incurred during the operating time, hence resulting in degrading performance. By modeling the system as a multistate deteriorating system, an optimal maintenance policy is obtained by determining the optimal number of standby components required in the system and the optimal state in which the replacement of deteriorating components shall be made.     

Optimal corrective maintenance contract planning for aging multi‐state system

This paper considers an aging multi‐state system, where the system failure rate varies with time. After any failure, maintenance is performed by an external repair team. Repair rate and cost of each repair are determined by a corresponding corrective maintenance contract with a repair team. The service market can provide different kinds of maintenance contracts to the system owner, which also can be changed after each specified time period. The owner of the system would like to determine a series of repair contracts during the system life cycle in order to minimize the total expected cost while satisfying the system availability. Operating cost, repair cost and penalty cost for system failures should be taken into account. The paper proposes a method for determining such optimal series of maintenance contracts. The method is based on the piecewise constant approximation for an increasing failure rate function in order to assess lower and upper bounds of the total expected cost and system availability by using Markov models. The genetic algorithm is used as the optimization technique. Numerical example is presented to illustrate the approach. Copyright © 2009 John Wiley & Sons, Ltd.     

基于修理设备的冷贮备可修系统的维修策略

本文研究了两同型部件,一个修理设备组成的冷贮备可修系统.在故障部件不能"修复如新"的条件下,分别以系统中部件1故障次数N,工作时间T和(N,T)为维修策略,利用更新过程和几何过程,求出修理设备经长期运行单位时间内平均停工时间表达式.并在部件寿命的分布函数和修理时间的分布函数已知的情况下,以部件1故障次数N为策略证明存在最优N*使修理设备经长期运行单位时间内平均停工时间最长.最后,通过数值例子验证最优策略的存在性.     

Cost and probabilistic analysis of series systems with mixed standby components

This paper deals with the reliability and availability characteristics of four different series system configurations with mixed standby (include cold standby and warm standby) components. The failure times of the primary and warm standby components are assumed to be exponentially distributed with parameters λ and , respectively. The repair time distribution of each server is also exponentially distributed with parameter μ. We derive the mean time-to-failure, MTTF, and the steady-state availability, A_T(∞), for four configurations and perform comparisons. For all four configurations, comparisons are done for specific values of distribution parameters and of the cost of the components. Finally, the configurations are ranked based on: MTTF, A_T(∞), and cost/benefit where benefit is either MTTF or A_T(∞).     

Allocations of cold standbys to series and parallel systems with dependent components

In the context of industrial engineering, cold‐standby redundancies allocation strategy is usually adopted to improve the reliability of coherent systems. This paper investigates optimal allocation strategies of cold standbys for series and parallel systems comprised of dependent components with left/right tail weakly stochastic arrangement increasing lifetimes. For the case of heterogeneous and independent matched cold standbys, it is proved that better redundancies should be put in the nodes having weaker [better] components for series [parallel] systems. For the case of homogeneous and independent cold standbys, it is shown that more redundancies should be put in standby with weaker [better] components to enhance the reliability of series [parallel] systems. The results developed here generalize and extend those corresponding ones in the literature to the case of series and parallel systems with dependent components. Numerical examples are also presented to provide guidance for the practical use of our theoretical findings.     

A novel optimal preventive maintenance policy for a cold standby system based on semi-Markov theory

A novel optimal preventive maintenance policy for a cold standby system consisting of two components and a repairman is described herein. The repairman is to be responsible for repairing either failed component and maintaining the working components under certain guidelines. To model the operational process of the system, some reasonable assumptions are made and all times involved in the assumptions are considered to be arbitrary and independent. Under these assumptions, all system states and transition probabilities between them are analyzed based on a semi-Markov theory and a regenerative point technique. Markov renewal equations are constructed with the convolution of the cumulative distribution function of system time in each state and corresponding transition probability. By using the Laplace transform to solve these equations, the mean time from the initial state to system failure is derived. The optimal preventive maintenance policy that will provide the optimal preventive maintenance cycle is identified by maximizing the mean time from the initial state to system failure, and is determined in the form of a theorem. Finally, a numerical example and simulation experiments are shown which validated the effectiveness of the policy.     

n个同型部件k个修理设备的冷贮备可修系统的可靠度研究

在设定元件的工作寿命和维修时间的分布都是负指数分布,全部随机变量都互相独立,发生故障的元件能够修成新的前提下,对由n个同种型号的元件和k(k≤n)个设备修理构成的冷贮存可修体系的可靠性方面进行分析,构建关于此体系的数学模型,获得了n个同种型号元件的冷贮存体系在k个设备修理的情况下的可靠度,且探讨在修理设备k值不相同的情况的可靠度,并针对n=3的情况下,分析修理设备数不相同情况下的可靠度。