带休假且有优先修理权的三部件串并联可修系统的分析

研究修理工带多重休假且有优先修理权的三部件串并联可修系统,其中假定系统只有一个修理工,部件可修复如新,部件1对其它部件有抢占优先修理权,其它两部件先坏先修,且打断的修理时间可以累积计算,运用补充变量的方法,在寿命分布为指数分布,维修分布为连续型分布的假定下,求得了系统的瞬态和稳态的可用度和可靠性指标,并给出一个特例.     

修理设备和开关不完全可靠的温贮备可修系统的可靠性

最近,KUO和KE[Reliability Engineering and System Safety. 2016, 145: 74-82, 参考文献[11]在假定部件故障后的修理时间以及修理设备故障后的修理时间均为一般分布的情形下,运用补充变量技术分别推导出三种可修系统模型的稳态可用度。然而作者并没有研究系统的瞬时可用度,本文在文献[11]的基础上,运用补充变量法推导出文献[11]中模型一的瞬时可用度的表达式。最后,用一个数值算例对所得结果进行了模拟实现。     

修理设备可修修理延迟的N个部件串联系统的随机性状及可靠性分析北大核心CSCD

考虑N(N≥2)个同型部件串联可修系统的随机性状及修理设备的可靠性.假设修理设备在修理失效部件的过程中可能失效,失效后的修理设备需要立即修理,部件失效后需要一段随机的延迟修理时间.进一步假定系统失效后好的部件可能劣化.利用马尔科夫更新过程工具和Takács的方法,研究系统的随机性状并利用随机性状研究结果得到该系统修理设备在时刻t的失效概率以及修理设备在(O,t)内的故障次数和故障频度以及一些有意义的推论.     

部件有两类故障状态且修理设备可更换的并联可修系统分析

本文考虑由两个同型部件组成的并联可修系统,每个部件有两类故障状态,部件故障后立即修理,且修理设备在修理故障部件的过程中也可能发生故障.假定部件的寿命和修理设备的寿命均服从指数分布,部件发生故障后的修理时间和修理设备故障后的更换时间均服从一般分布,利用马尔可夫更新过程理论,求得系统的有关可靠性指标和修理设备的闲期长度和"广义忙期"长度等一系列结果.     

修理设备可更换且修理有延迟的两不同型部件并联可修系统

假定部件的寿命服从指数分布,其修理延迟时间和修理时间均服从一般分布,并且修理设备的寿命服从指数分布,其更换时间服从一般分布,利用马尔可夫更新过程理论和一种新的分解方法,研究了修理设备可更换且修理有延迟的两不同型部件并联可修系统,求得了系统和修理设备有关可靠性指标的一系列结果.     

离散时间单部件可修系统瞬时可用度的渐近稳定性

针对离散时间下修理有延迟的单部件可修系统,研究了有限时间约束下的系统瞬时可用度模型.证明了该系统瞬时可用度的渐近稳定性,并得到了系统稳态可用度的表达式.结果表明系统瞬时可用度的稳定性对离散时间系统和连续时间系统具有一致性,进一步说明了离散时间下瞬时可用度模型的有效性,同时也加强了研究有限时间段内系统瞬时可用度波动的理论基础.     

修理设备可更换且有修理延迟的N部件串联系统分析

假定部件的寿命服从指数分布,修理延迟时间和修理时间均服从任意分布,并且修理设备的寿命服从指数分布,其更换时间服从任意分布的情况下,利用马尔可夫更新过程理论和拉普拉斯变换工具,研究了修理有延迟且修理设备可更换的n部件串联可修系统,求得了系统的可用度和(0,t]时间内的平均故障次数.进一步,在定义修理设备“广义忙期”下,利用全概率分解,提出了一种新的分析技术,讨论了修理设备的可靠性指标,得到修理设备的一些重要可靠性结果.     

具有两类失效模式和修理工休假的重试系统可靠性分析

本文考虑具有两类失效模式和Bernoulli休假的可修表决重试系统,系统中每个部件或者正常工作,或者以概率p类型a失效,或者以概率1-p类型b失效.修理工修理完一个部件后,可能以概率h进行休假,也可能以概率1-h在系统中空闲.系统中没有等待空间,失效部件如果不能立即得到修理,则进入重试空间,一段时间后再进行重试,直到得到修理.利用马尔可夫过程理论和拉普拉斯变换等方法,得到了系统的稳态可用度、可靠度函数和系统首次故障前平均寿命等可靠性指标.通过数值例子分析了系统参数对可靠性指标的影响.     

单向关闭两不同部件串联一部件冷贮备的三部件可修系统的可靠性

本文考虑单向关闭两个不同型部件串联和一个部件冷贮备的可修系统的可靠性.假设所有部件的寿命均为指数分布,修理时间为一般连续型分布.利用补充变量法,拉普拉斯变换和拉普拉斯-斯梯阶变换工具,研究系统的可用度,系统的可靠度以及系统在(0,t]内的故障频度.     

对修理期间部件无老化的串联系统可用度的进一步探讨

一般认为串联系统多部件中至多允许一个部件失效且其他部件服从于统计独立情况.论述了修理期间部件无老化的串联系统分别在统计独立情况下及包含共因失效情况下的稳态可用度,并对给出一般表达式.     

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。     

An ideal way of obtaining an optimal inspection permutation for a system with components connected in series

The problem of an inspection permutation or inspection strategy (first discussed in a research paper in 1989 and reviewed in another research paper in 1991) is revisited. The problem deals with an N‐component system whose times to failure are independent but not identically distributed random variables. Each of the failure times follows an exponential distribution. The components in the system are connected in series such that the failure of at least one component entails the failure of the system. Upon system failure, the components are inspected one after another in a hierarchical way (called an inspection permutation) until the component causing the system to fail is identified. The inspection of each component is a process that takes a non‐negligible amount of time and is performed at a cost. Once the faulty component is identified, it is repaired at a cost, and the repair process takes some time. After the repair, the system is good as new and is put back in operation. The inspection permutation that results in the maximum long run average net income per unit of time (for the undiscounted case) or maximum total discounted net income per unit of time (for the discounted case) is called the optimal inspection permutation/strategy. A way of determining an optimal inspection permutation in an easier fashion, taking advantage of the improvements in computer software, is proffered. Mathematica is used to showcase how the method works with the aid of a numerical example. Copyright © 2016 John Wiley & Sons, Ltd.     

A finite horizon model for repairable systems with repair restrictions

In this paper, we will present a new finite horizon repair/replacement decision model and derive the structure of the optimal policy for components that have a failure intensity that is a non-decreasing function of the number of times the component has been repaired, and independent of the component's age. Furthermore, the component has physical restrictions on the number of times it can be repaired, after which the only feasible decision is to replace the component. The fundamentals of this new decision model are based on the outcomes of several case studies done by the authors. Besides presenting the model and showing the structure of the optimal policy, the model will be applied to a real industry data set, and its results discussed.     

Inspection and duplication

In a cyclic industrial process a certain component fails during a cycle with probabilityp. In order to increase the reliability of the process, the component is duplicated in parallel with one or two redundant components of the same kind. The components fail independently of each other. To further increase the reliability, the system can be inspected aftern cycles, given that it has not failed during the previousn?1 cycles. Upon inspection failed components are repaired. In order to choose the inspection intervaln, the conditional probability that the system fails during cycle non, given that it has not failed during the previousn?1 cycles, is calculated.     

有延迟修理的两部件串联系统的预防维修策略

研究由两个部件串联组成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.当部件发生故障后进行故障维修,因为各种原因可能会延迟修理.部件在每次故障维修后的工作时间形成随机递减的几何过程,且每次故障后的维修时间形成随机递增的几何过程.以部件进行预防维修的间隔T和更换前的故障次数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.     

Optimally maintaining a Markovian deteriorating system with limited imperfect repairs

We consider the problem of optimally maintaining a periodically inspected system that deteriorates according to a discrete-time Markov process and has a limit on the number of repairs that can be performed before it must be replaced. After each inspection, a decision maker must decide whether to repair the system, replace it with a new one, or leave it operating until the next inspection, where each repair makes the system more susceptible to future deterioration. If the system is found to be failed at an inspection, then it must be either repaired or replaced with a new one at an additional penalty cost. The objective is to minimize the total expected discounted cost due to operation, inspection, maintenance, replacement and failure. We formulate an infinite-horizon Markov decision process model and derive key structural properties of the resulting optimal cost function that are sufficient to establish the existence of an optimal threshold-type policy with respect to the system’s deterioration level and cumulative number of repairs. We also explore the sensitivity of the optimal policy to inspection, repair and replacement costs. Numerical examples are presented to illustrate the structure and the sensitivity of the optimal policy.     

Optimal inspection of a complex system subject to periodic and opportunistic inspections and preventive replacements

This paper proposes two optimization models for the periodic inspection of a system with “hard-type” and “soft-type” components. Given that the failures of hard-type components are self-announcing, the component is instantly repaired or replaced, but the failures of soft-type components can only be detected at inspections. A system can operate with a soft failure, but its performance may be reduced. Although a system may be periodically inspected, a hard failure creates an opportunity for additional inspection (opportunistic inspection) of all soft-type components. Two optimization models are discussed in the paper. In the first, soft-type components undergo both periodic and opportunistic inspections to detect possible failures. In the second, hard-type components undergo periodic inspections and are preventively replaced depending on their condition at inspection. Soft-type and hard-type components are either minimally repaired or replaced when they fail. Minimal repair or replacement depends on the state of a component at failure; this, in turn, depends on its age. The paper formulates objective functions for the two models and derives recursive equations for their required expected values. It develops a simulation algorithm to calculate these expected values for a complex model. Several examples are used to illustrate the models and the calculations. The data used in the examples are adapted from a real case study of a hospital’s maintenance data for a general infusion pump.     

修如新模型下设备的可用度

对可维修的设备考虑一类修如新模型,导出了在该模型下设备在任意时刻的可用度函数.     

负载分担并联可修系统的可靠性分析

针对负载分担可修的并联系统模型,考虑了控制器可修,修理工多人的情形,并且在将控制器作为关键部件优先维修的规则下,对模型进行了可靠性分析.最后用一个实例,求得一些常见的系统可靠性指标,并结合部件的失效率和修复率进行了深入讨论,在系统不可修时求得其可靠度和平均寿命.     

单部件可修系统的一个几何过程维修模型

本文研究了单部件、一个修理工组成的可修系统的最优更换问题,假定系统不能修复如新,以系统年龄T为策略,利用几何过程求出了最优的策略T^*,使得系统经长期运行单位时间内期望效益达到最大,并求出了系统经长期运行单位时间内期望效益的显式表达式。在一定条件下证明了T^*的唯一存在性。最后还证明了策略T^*比文献[6]中的策略T^*优。