系统可靠性分配的优化方法

本文根据系统元件重要度分析理论,提出一种优化的元件可靠性分配的新方法.它以所给定的系统可靠度为目标,以元件最大可靠度为限止,根据元件重要度排序,逐步分配元件可靠性,使其保证每一步的分配是最优的,从而得到一个整体优化的分配方案,以提供作为可靠性设计的依据。本文最后还给出一个简单算例。该方法思路简单明了,计算方便。     

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.     

两不同部件冷贮备系统的最优备件定购策略分析

本文研究了两不同部件冷贮备系统的最优备件定购策略问题，特别把替失下来的部件所能回收的费用引入模型假设，并且紧急定购备件的交付周期为随机变量，得到了在一定条件限制下的最优通常定购时间，它使得以长期运行单位时间内的期望费用达到最小或者使得系统的稳态可用度达到最大。     

基于多种约束条件的维修备件库存优化方法研究

考虑了维修备件需求的随机性,以装备可用度、完好率置信度以及维修备件的保障程度为约束条件,运用概率论与数理统计方法,将维修备件保障费用达到最小值确定为目标函数,在此基础上,制定维修备件库存的最优方案,并通过示例验证了该方法的有效性和科学性.方法可以为其它相关领域解决物资库存与费用问题提供理论依据.     

大型网络基于连通可靠度的最优可靠度分配

由于网络连通可靠度计算属于NP-hard问题,当系统可靠度无法显式表达时,基于连通可靠度的大型复杂网络优化通常只能采用启发式优化算法解决．通过对复杂网络连通可靠度算法结构的分析,给出了系统连通可靠度的Taylor方程．采用遗传算法,由系统连通可靠度的Taylor方程确定种群适应值,得到一个系统最优可靠度分配方案;将最优解带入改进Minty算法或递推分解算法中,计算该最优解的连通可靠度精确值和对应的连通可靠度的Taylor展开方程;再次采用遗传算法求最优解．当最优解对应的可靠度精确值和Taylor方程算得得近似值误差小于指定精度时,则此最优解为最终的系统最优可靠度分配方案A·D2将此优化过程称为迭代遗传算法．算例显示迭代遗传算法不仅可用于大型网络的连通可靠度最优分配,而且优化迭代过程中可以得到多组阶段最优解,这些解均落在最优解附近,构成了近似最优解群,在实际工程优化中拓展了选择面．     

基于保障度的战时三级备件保障优化研究

针对装备备件保障度问题,结合现有的研究现状,综合考虑了战时装备保障的实际情况和新旧备件使用寿命的差异,深入分析了备件调度对保障度的影响,以保障度为目标函数,建立了战时三级备件保障模型,运用经典的排序算法对模型进行求解。最后,算例表明该方法是有效性的。     

系统可靠度最优分配的一种算法

可靠度最优分配是系统设计、研制过程中需考虑的一个重要问题,其目的是从整体出发,将有限资源加以最有效地利用。本文将部件(元件)概率重要度应用于复杂系统(如网络系统)可靠性设计中,提出了一种系统可靠度最优分配问题中费用最小化的启发式算法。本算法直观、简单,易于在计算机上实现,而且系统设计者能全面了解整个优化过程,适合工程应用。本文还举例对算法进行了说明和比较,并表明本算法是精确可靠的。     

一般δ-冲击模型及其最优更换策略

本文讨论了一种具有一般δ-冲击的可修系统，我们不仅给出了该系统的一些可靠性指标，如系统的可靠度，系统平均工作时间，系统工作时间的极限分布等，而且对该可修系统的分布性质也进行了研究．在Poisson冲击下，我们证明了该系统的寿命分布是NBU的．在该系统为”修复非新”时，我们利用几何过程考虑了以系统的故障次数N为更换策略，以长期运行单位时间内的期望费用为目标函数，通过目标函数最小化确定了最优更换策略．最后我们给出了一个数值例子．     

典型串并联系统的备件库存优化模型

选取典型串并联系统的备件库存优化为研究对象,以系统供应可用度最大为目标,备件总购置费为约束条件构建备件库存优化模型,给出基于边际分析法的优化算法.经示例分析,验证了该模型的可行性和有效性,结果可为备件保障经费的合理配置提供理论依据.     

多约束条件下三状态复杂系统的优化分配

研究了三状态复杂系统在多约束条件下可靠度的问题.以串-并联系统为研究对象,利用选取重要度来提高系统可靠度的方法,获得了重要度对系统可靠度有着重要影响的结果,并通过算法、例题对实例进行了验证.     

Optimum component test plans for phased-mission systems

We consider the component testing problem of a system that has to perform a mission consisting of a sequence of stages. Once a stage is over, all failed components of the system are replaced before the next stage starts in order to improve its reliability. The components have exponential life distributions where the failure rates depend on the stage of the mission. We formulate the optimal component testing problem as a semi-infinite linear program. We present an algorithmic procedure to compute optimal test times based on the column generation technique and illustrate with numerical examples.     

智能电表最优更换及备件库存联合决策

智能电表是智能电网运行的关键部件,提高其可靠性和可用度对保证电力的持续不间断供应和准确电能测量至关重要。充足的智能电表库存是其换装与维修的基本保障。本文基于智能电表的故障特性和换装需求分析,建立了智能电表的最优更换与备件库存联合决策模型,并给出了优化方法,以求得可以使系统长期平均运营成本最小的最优更换与备件库存策略。     

An efficient memetic algorithm for the graph partitioning problem

We consider the component testing problem of a device that is designed to perform a mission consisting of a random sequence of phases with random durations. Testing is done at the component level to attain desired levels of mission reliability at minimum cost. The components fail exponentially where the failure rate depends on the phase of the mission. The reliability structure of the device involves a series connection of nonidentical components with different failure characteristics. The optimal component testing problem is formulated as a semi-infinite linear program. We present an algorithmic procedure to compute optimal test times based on the column generation technique, and illustrate it with numerical examples.     

Component testing of repairable systems in multistage missions

We consider the component testing problem of a device that is designed to perform a mission consisting of a sequence of stages. Once a stage is over, the device is overhauled to replace all failed components before the next stage starts to improve mission reliability. The components fail exponentially where the failure rate depends on the stage of the mission. The reliability structure of the device involves a series connection of redundant subsystems. The optimal component testing problem is formulated as a semi-infinite linear programme. We present an algorithmic procedure to compute optimal test times based on the column generation technique, and illustrate it with numerical results.     

面向多阶段任务的武器系统备件优化配置建模

资源优化配置是作战单元维修保障的关键因素.当作战单元执行单阶段任务时,讨论了部件结构为串联系统和k/n系统的任务成功概率建模问题,在此基础上,建立了k/n结构动态变化的多阶段任务系统的任务成功概率模型.在满足系统任务成功概率约束条件下,给出了防空作战单元备件携行量优化模型,并运用边际分析法进行了求解,通过示例表明了模型的正确性.     

Reliability Importance and Invariant Optimal Allocation

The reliability importance of a component is a partial derivative of the system reliability with respect to this component reliability. When all components are i.i.d., the reliability importance is called the B-importance. Relationships between reliability allocation and the reliability importance for general coherent systems are explored. The invariant optimal allocation is an allocation related only to the relative ordering rather than the magnitude of the component reliabilities. A strong heuristic method (LK heuristic) is developed to search for an ideal allocation through the application of the reliability importance.The following conclusions are drawn: if there exists an invariant optimal allocation for a system, the optimal allocation is to assign component reliabilities according to the B-importance ordering. Furthermore, the allocation generated by the LK heuristic is the optimal allocation.     

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。     

基于系统可靠性的组件综合重要度变化机理分析

重要度理论是一种重要的系统薄弱环节识别和评估方法,被广泛应用于系统可靠性设计优化、维修资源分配、维修决策以及风险分析等领域。本文以组件状态转移率为纽带,分析了组件综合重要度对系统可靠性的影响机理,识别对系统可靠性变化影响最大的组件,综合重要度评估了单位时间内系统可靠性的变化。首先给出综合重要度的定义;其次讨论系统可靠性的组件重要度表示方法;最后在串联和并联系统中,分析综合重要度随着组件状态转移率的变化机理。     

Cold vs. hot standby mission operation cost minimization for 1-out-of-N systems

It is well recognized that using the hot standby redundancy provides fast restoration in the case of failures. However the redundant elements are exposed to working stresses before they are used, which reduces the overall system reliability. Moreover, the cost of maintaining the hot redundant elements in the operational state is usually much greater than the cost of keeping them in the cold standby mode. Therefore, there exists a tradeoff between the cost of losses associated with the restoration delays and the operation cost of standby elements. Such a trade-off can be obtained by designing both hot and cold redundancy types into the same system. Thus a new optimization problem arises for the standby system design. The problem, referred to in this work as optimal standby element distributing and sequencing problem (SE-DSP) is to distribute a fixed set of elements between cold and hot standby groups and select the element initiation sequence so as to minimize the expected mission operation cost of the system while providing a desired level of system reliability. This paper first formulates and solves the SE-DSP problem for 1-out-of-N: G heterogeneous non-repairable standby systems. A numerical method is proposed for evaluating the system reliability and expected mission cost simultaneously. This method is based on discrete approximation of time-to-failure distributions of the system elements. A genetic algorithm is used as an optimization tool for solving the formulated optimization problem. Examples are given to illustrate the considered problem and the proposed solution methodology.     

Spares provisioning under performance-based logistics contract: profit-centric approach

Performance-based logistics (PBL) is emerging as a preferred logistic support strategy within the public sector, especially the Department of Defence. Under a PBL strategy, the customer buys performance, such as operational availability, mission readiness and operational reliability, instead of contracting for a specified collection of resources defining the underlying support infrastructure. The literature on PBL is still in its infancy and additional research is required to optimize logistic resources such as spare parts, equipment, facilities, labour etc within a PBL context. In this paper, an optimization model is developed for spares provisioning under a multi-item, multi-echelon scenario. The objective of the optimization model is to maximize the profit to the supplier under a PBL contract.