面向k-out-of-n:f系统的两阶段周期维护策略研究

以k-out-of-n:f系统为研究对象,针对系统故障率和维护成本随年龄增加而增加的现象,提出了两阶段维护策略.在第一阶段,对发生的一切故障采用最小维护处理.在第二阶段,对第一类故障不做处理,当发生第二类故障时即通过替换使系统恢复正常,若到达预防维护周期时仍无第二类故障发生,则对系统进行预防性维护.在模型基础上,运用有...     

不完备生产与条件维护策略下的生产批量决策研究

构建了不完备生产与条件维护下的生产批量模型,采用威布尔分布的曲线分布宽度描述可靠性的退化性,考虑了曲线分布宽度为等比数列和等差数列2种模型,利用报酬更新理论求解了期望平均总成本的最小值。结果表明,第1种模型的期望平均总成本要高于设备不具有退化性的期望平均总成本,前者的条件维护的阈值、最优生产批量和维护次数都比后者的少;第2种模型的期望平均总成本总体要低于设备不具有退化性的期望平均总成本,前者的条件维护的阈值比后者的少,而前者的维护次数和最优生产批量都比后者的多。研究还发现,公比和公差是影响期望平均总成本的最重要因素,需求是影响条件维护的可靠性阈值的最重要因素。本文的相关启示可为管理者提供决策参考依据。     

Optimal preventive maintenance strategy using two repair crews having different efficiencies: a quasi renewal process based modelling approach

This paper considers randomly failing, single-unit equipment subject to a periodic preventive maintenance (PM) policy. In case of failure between successive perfect PM actions (renewals), imperfect repairs are performed following a decreasing quasi-renewal process. One of two different maintenance crews can perform the repairs. One team is more experienced, and consequently more efficient than the other, but more costly. A mathematical model is developed in order to determine the PM period, T, and the kth repair, during a PM period, after which the repair team should be changed, minimising the average total cost per time unit over an infinite time span. It is also proved that an optimal solution in terms of the PM period always exists for any given system lifetime distribution and any set of maintenance costs. Numerical examples are presented and the obtained results are discussed.     

Effects of maintenance policy on an imperfect production system under trade credit

The traditional production model development assumed that all products are perfect quality and did not consider maintenance, which is far from reality. In practice, the production process may shift randomly from an in-control state to an out-of-control state during a production run, i.e. process deterioration. This paper considers both preventive maintenance and corrective maintenance which are used to increase the system reliability. The objective of this paper is to determine the optimal production run time and maintenance frequency while minimising the total cost under process deterioration and trade credit. This paper develops a theorem and an algorithm to solve the problem described, provides numerical analysis to illustrate the proposed solution procedure, and discusses the impact of various system parameters. A real case of hi-tech manufacturer is used to verify the model. It predicts a 10.36% decrease in total cost if the preventive maintenance decision is considered.     

Assigning licenced technicians to maintenance tasks at aircraft maintenance base: a bi-objective approach and a Chinese airline application

Assigning technicians to maintenance tasks at an aircraft maintenance base is challenging and needs to consider technician licences, fairness and such operational constraints as hangar capacity and work shifts. We formulate the problem as a bi-objective optimisation model, which minimises total cost while simultaneously achieving fairness in workload allocation among different technicians. A tabu-based heuristic algorithm is developed to obtain Pareto efficient solutions. The algorithm is shown to be effective through comparison with CPLEX. A case study from a major Chinese airline demonstrates that our optimisation-based approach is applicable and beneficial to the practice. Managerial issues on maintenance workforce management are examined as well. The results show that training technicians and upgrading their licences may not be better off, and increasing the number of technicians has both favourable and unfavourable effects.     

Optimum Maintenance and Availability of Series Systems Subject to Imperfect Repair

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不完整结构系统同时考虑强度和刚度的可靠性分析

基于结构强度可靠性分析理论的基础之上,提出了不完整结构(结构系统中有部分元件已失效,但结构未变成机构仍具有一定的承载能力)强度、刚度可靠性的分析方法.该方法考虑了元件因强度失效对不完整结构系统强度、刚度可靠性的影响,同时导出了等效安全余量的形式,进而计算结构系统在失效各阶段的总体失效概率.并结合算例对结构系统在失效各阶段进行了强度、刚度的可靠性分析.算例表明,这样分析符合结构在使用各阶段可靠性的真实情况,从而为结构的合理利用起指导性作用.     

Fatigue issues in aircraft maintenance and repairs

Many design considerations are involved in ensuring structural integrity of Boeing jet transports, which have common design features validated by extensive analyses, tests, and service performance. Designing for continued structural integrity in the presence of damage such as fatigue or corrosion is an evolutionary process. Performance demands, increasing structural complexity, and aging fleet reassessments have required development of standards suitable for application by large teams of engineers. This presentation is focused on such methods with special emphasis on practical fatigue reliability considerations. Durability evaluations are based on quantitative structural fatigue ratings which incorporate reliability considerations for test data reduction and fleet performance predictions. Fatigue damage detection assessments are based on detection reliability estimates coupled to damage growth and residual strength evaluations. Data are presented to airline operators on detection check forms which permit efficient maintenance planning to achieve required fatigue damage detection reliability levels.     

静态多路径分配法在公路网规划中的应用

介绍了静态多路径交通分配方法的模型建立和程序设计。并从有效出行路线的确定，最短路权的计算，有效路段的边权及节点点权计算，各路段交通量(简称OD)分配率及分配交通量的计算等方面给出了该模型的算法与程序框图。同时，对该方法在广珠高速公路规划中交通量分配预测的实际应用、软件实现，进行了分析探讨。根据所得结果，表明该方法优于最短路径法，为广珠高速公路的规划建设提供了科学的数据依据。