基于隐藏故障和竞争失效的多态系统视情维修策略

针对具有隐藏故障和竞争失效模式的多态系统维修策略问题,提出了一种综合考虑隐藏故障损失成本、竞争失效模式、不完美检测、不完美维修等因素的多态系统维修建模方法。首先,描述了多态系统及其失效准则,并给出具体的视情维修策略;其次,推导了系统因隐藏故障而导致的损失成本,并对缺陷状态的不完美检测和不完美维修情形进行了数学描述;然后,分析计算了竞争失效模式下系统的两种更新情形及其发生概率,并基于此构建了多态系统的维修模型-期望成本率;最后,通过数值算例验证了所构建维修模型的有效性,分析结果表明,通过优化维修模型能够找到系统的最佳检测策略,从而有效降低维修成本。     

带有一个冷贮备部件的两部件串联系统机会维修策略

针对带有一个冷贮备部件的两部件串联系统,本文首先提出一种预防维修与机会维修相结合的维修策略,运用更新报酬定理求得长期运行情况下的单位时间期望维修成本函数的表达式,然后研究最优的机会维修阀值,运用微分学理论求解最优解,最后用实例验证理论的正确性,从实际例子说明本文提出的维修策略可明显节约维修成本,为相应的带有冷贮备的多部件串联系统的维修策略分析提供参考,对企业设备的维修有实际指导意义。     

基于部件等级更新和组重要度的维修策略

针对多部件系统,提出一种基于部件等级更新和组重要度并考虑备件订购的维修策略.首先定义部件等级来确定系统结构,引入生存signature来更新随部件等级更新的系统结构,基于系统可靠度和维修成本建立一个组重要度,并基于当前的系统结构、部件平均故障时间和订购成本设计一个备件订购规则.基于以上,提出适应性故障维修规则和两层面预防维修规则并建立相应的维修模型,使用遗传算法对其优化.最后,以变电站自动化系统为例验证了该策略既可改善系统可靠度,又可降低维修费用,对维修的理论和实践有较大价值.     

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。     

延迟时间生产系统预防维修策略和X-bar控制图联合经济设计

针对生产过程输出质量特性服从正态分布的单部件延迟时间生产系统,研究了预防维修策略和X-bar控制图联合经济设计问题.首先,在将延迟时间系统界定为受控、失控、故障3种结果状态基本内容前提下,根据维修时系统可能存在的实际状态和控制图监测结果关系,分析构建了生产系统维修方式和控制图监测的耦合机制;在此基础上,以期望单位时间最小成本为目标,以系统维修成本、产品质量抽检成本、不合格品的生产费用、维修停机生产损失为考虑成本内容,利用更新过程理论建立了生产系统预防维修策略和X-bar控制图联合决策数学模型;然后基于数值仿真示例,利用遗传算法对模型的求解进行了分析验证.实例分析结果表明,文章模型可行有效.最后,利用部分因子试验设计方法对模型参数进行了敏感性分析.     

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.     

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。     

基于遗传算法和非线性规划的设备预防维修周期优化模型

本文通过建立预防性维修前后故障率的关系,给出了带约束的非线性设备预防性维修策略模型.该模型通过综合考虑故障维修成本、预防性维修成本、以及生产损失成本,在有限的生产运行时间内使得系统总成本最小化.模型利用遗传算法的全局搜索能力和非线性规划的局部搜索能力进行求解.计算结果表明,遗传算法结合非线性规划可以以较快的收敛速度达到全局最优.     

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。     

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。     

Optimal preventive maintenance policy for electric power distribution systems based on the fuzzy AHP methods

In power distribution systems, with their great vastness and various outage causes, one of the most important problems of power distribution companies is to select a suitable maintenance strategy of system elements and method of financial planning for the maintenance of system elements with the two objectives of decrease in outage costs and improvement of system reliability. In this article, a practical method is introduced for the selection of a suitable system elements maintenance strategy; moreover, to plan the preventive maintenance budget for the system elements, two methods are offered: the cost optimization method and the fuzzy Analytic Hierarchy Process (AHP) method. In the former method, a new model of system maintenance cost is offered. This model, based on system outage information, the elements maintenance costs are determined as functions of system reliability indices and preventive maintenance budget. The latter method, too, a new guideline is introduced for considering the cost and reliability criteria in the trend of preventive maintenance budget planning. In this method, the preventive maintenance budget for the elements is determined based on relative priority of elements with reliability criteria. © 2015 Wiley Periodicals, Inc. Complexity 21: 70–88, 2016     

Age-dependent production planning and maintenance strategies in unreliable manufacturing systems with lost sale

In this paper, we formulate an analytical model for the joint determination of an optimal age-dependent buffer inventory and preventive maintenance policy in a production environment that is subject to random machine breakdowns. Traditional preventive maintenance policies, such as age and periodic replacements, are usually studied based on simplified and non-realistic assumptions, as well as on the expected costs criterion. Finished goods inventories and the age-dependent likelihood of machine breakdowns are usually not considered. As a result, these policies could significantly extend beyond the anticipated financial incomes of the system, and lead to crises. In order to solve this problem, a more realistic analysis model is proposed in this paper to consider the effects of both preventive maintenance policies and machine age on optimal safety stock levels. Hence, a unified framework is developed, allowing production and preventive maintenance to be jointly considered. We use an age-dependent optimization model based on the minimization of an overall cost function, including inventory holdings, lost sales, preventive and corrective maintenance costs. We provide optimality conditions for the manufacturing systems considered, and use numerical methods to obtain an optimal preventive maintenance policy and the relevant age-dependent threshold level production policy. In this work, this policy is called the multiple threshold levels hedging point policy. We include numerical examples and sensitivity analyses to illustrate the importance and the effectiveness of the proposed methodology. Compared with other available optimal production and maintenance policies, the numerical solution obtained shows that the proposed age-dependent optimal production and maintenance policies significantly reduce the overall cost incurred.     

系统最佳维修策略研究

一个复杂系统通常由多个不同部件组成，考虑到这些部件有各自不同的失效率及维修时间，本提出了一种新的维修策略模型，该模型考虑了不同部件的差异性及对系统的不同重要性，在一定可用度要求下，使系统总平均费用达到最小的最佳预防维修周期，并给出了相应的仿真算法。     

A new preventive maintenance strategy for items sold under warranty

When products are sold under warranty, the manufacturer incursadditional costs for warranty servicing. Preventive maintenanceactions can be used to reduce this cost and these are worthwhileonly if the extra cost incurred is less than the reduction achieved.In this paper we propose a new preventive maintenance policywhere the parameters are selected optimally to minimize thetotal warranty servicing cost.     

Maintenance models in warranty: A literature review

Along with increasing the warranty period for complex systems, reducing the warranty servicing costs has become an issue of great importance to the manufacturers. One possible way to reduce the expected warranty servicing cost is by making sound decision on the product warranty and maintenance strategies. Therefore, warranties (basic warranty and extended warranty) and maintenance (corrective and preventive) are strongly interlinked and of great interest to both manufacturers and customers. This paper is the first identifiable academic literature review to deal with warranty and maintenance. It provides a classification scheme for the articles that link warranty and maintenance published between 2001 and 2011 covering 44 journals and proposes a taxonomy scheme to classify these articles. Nine hundred articles were identified for their relevance to warranty and were carefully reviewed. One-hundred and twenty-two articles were subsequently selected for their relevance to maintenance and included in the classification.     

Modelling generator maintenance scheduling costs in deregulated power markets

Generating companies use the maintenance cost function as the sole or main objective for creating the maintenance schedule of power generators. Usually only maintenance activities related costs are considered to derive the cost function. However, in deregulated markets, maintenance related costs alone do not represent the full costs of generators. This paper models various cost components that affect the maintenance activities in deregulated power markets. The costs that we model include direct and indirect maintenance, failures, interruptions, contractual compensation, rescheduling, and market opportunity. The loss of firm’s reputation and selection of loyalty model are also considered using the Analytic Hierarchy Process (AHP) within an opportunity cost model. A case study is used to illustrate the modelling activities. The enhanced model is utilised in generator maintenance scheduling cases. The experimental results demonstrate the importance and impact of market related costs in maintenance schedules.