数据仓库在航空维修信息分析中的应用研究

在空军航空维修管理信息系统的基础上,提出了一个航空维修信息分析系统研究模型,应用此模型可以对航空维修信息进行联机分析处理,并用决策树算法及关联规则算法进行数据挖掘,以实现对航空维修信息的智能分析。     

多部件串联系统的定期预防性维修策略初探绎

针对多部件串联系统,提出了一种定期预防性维修策略.首先,介绍了多部件串联系统的一般模型和3种维修策略;其次,分析了定期预防维修的成本,并构建了优化模型;然后,利用遗传算法实现了成本最小化;最后,通过案例,将3种维修策略的成本进行了比较,结果表明,文中提出的定期预防维修策略的维修成本最低,具有一定的推广使用价值.     

可维修闭环系统G0法等效代换思路

在交通物流,航空航天,国防工业等工程系统中,大多数是可维修的闭环系统.因此,研究闭环可维修系统可靠性分析中的G0法,并进行改进,很有价值.文中提出了闭环可维修系统可靠性基本模型和算法改进,并推导了计算过程,得到该基本模型下系统可靠性的计算公式,同时提出一种等效思想,将复杂系统等效成基本模型,只需找出两者之间的等效代换关系一一等效失效率和等效修复率,将代换式带入基本计算公式中,直接得到复杂系统可靠性分析,该算法和思路为闭环系统的可靠性设计,维护,分析提供了理论依据和新的方法.     

维修员工数量配置的优化模型

为解决由于维修员工的数量设置不当,造成人力资源利用率低、成本高的问题,基于排队论原理,采用数学建模方法对维修部门在单位时间内到达的顾客数和安排的维修员工数进行了分析.维修部门的工作情况为:多服务台对多个顾客进行服务,服务时间为随机型,输入过程为平稳型.通过分析,建立数学模型,排队模型采用M/M/c/∞/∞模型.首先对维修部门进行初步调查,了解顾客对排队的感想及维修员工设置的基本数据,然后利用模型分析计算出员工数量分配的最佳方案.通过数学建模,更好地利用了维修人力资源,也可应用于其他维修部门的员工数量配置.     

基于Gamma过程的单部件系统预防维修与更换策略

针对一类伽马（Gamma）劣化失效的单部件系统,提出了一种预防维修和预防更换策略。用伽马分布描述了系统的劣化过程,部件为不完全维修,系统维修效果假定服从正态分布。所建立的模型以部件生命周期单位时间内期望费用作为优化目标,通过求解模型可以确定预防性维修的次数、预防维修和预防更换的阈值。最后通过对一个伽马退化部件进行案例分析,验证了模型的可操作性。     

虚拟维修训练系统过程建模研究

寻求一种简洁的模型描述维修训练过程,进而对虚拟维修训练中各个训练要素之间的交互和相互作用进行控制,以实现维修过程施训者和受训者的训练意图,达到预期的训练效果。提出了基于活动的过程模型,更加注重训练自身的自主性与交互性。利用UML活动图描述维修过程,描述虚拟维修过程主体的行为,并分析其与系统中维修对象与维修信息的关系,有效地支持虚拟维修训练系统的开发。     

大型相控阵雷达天线阵面视情维修优化模型

针对大型相控阵雷达天线阵面维修保障特点,提出了一种视情维修策略。当天线阵面中故障部件总数达到一定数量后,装备停机并开始换件维修。以天线阵面使用可用度为约束条件,以期望维修费用率最低为优化目标,建立了大型相控阵雷达天线阵面视情维修优化模型,并提出了一种求解最佳视情维修阈值和最佳换件维修人数的数值迭代算法。最后,通过具体实例验证了模型与算法的可行性。该模型可为大型相控阵雷达预防性维修决策提供理论依据。     

基于定期维修的k/N系统维修渠道优化模型

针对定期维修策略下的k/N系统维修渠道的配置问题,建立了多类故障单元批量定期送修的维修渠道优化模型。首先,给出了定期维修策略下的k/N系统工作流程和故障单元维修流程;然后,根据故障单元批量定期送修的特点,提出了Dξ/M/c排队模型,并对关键输入参数进行了修正与计算,对排队系统的稳态概率进行了求解;接着,建立了多类故障单元同时送修的维修渠道优化模型,通过将多类顾客源多服务台排队系统转化为单类顾客源多服务台排队系统,对优化模型进行了求解;最后,通过算例仿真与分析,对模型进行了验证。结果表明,该模型能够为k/N系统维修渠道数量的确定提供理论依据,对部队维修资源的合理配置具有一定的指导意义。     

大型相控阵雷达天线阵面备件优化配置研究

针对大型相控阵雷达天线阵面视情维修与定期维修在维修时机上存在交叉的现象,将视情维修与定期维修相结合,提出了一种基于m/T维修策略大型相控阵雷达天线阵面备件优化配置模型。首先,在对m/T维修策略分析的基础上,建立了系统的使用可用度模型,并利用0-1分布对使用可用度进行了求解计算;然后,以使用可用度为约束条件,以LRU备件配置费用最小为优化目标,对大型相控阵雷达天线阵面备件配置进行了优化研究;最后,通过实例验证了该优化模型的有效性。     

维修保障信息系统互操作性等级评估研究

互操作性是信息化条件下联合作战维修保障信息系统形成整体维修保障能力的基础,对于提高维修保障效能具有重要作用.本文论述了维修保障信息系统的互操作性,总结归纳了现有的互操作性等级评估模型,并针对维修保障任务的特点,从技术维、功能维、语义维构建了维修保障信息系统互操作性等级评估模型,对今后维修保障信息系统建设具有指导意义.     

A failure-repair model with minimal and major maintenance

A Markov model for a continuously operating service device whose condition deteriorates with time in service is proposed. The model incorporates deterioration and Poisson failures, minimal repair, periodic minimal maintenance, and major maintenance after a given number of minimal maintenances. An exact recursive algorithm computes the steady-state probabilities of the device. A cost function is defined using different cost rates for the different types of outages. Based on minimal unavailability or minimal costs, optimal solutions of the model are derived. Major maintenance is seldom beneficial if optimal maintenance intervals are used. If a maintenance policy is based on nonoptical intervals between maintenances, periodic major maintenance can reduce costs     

Replicated Object Management with Periodic Maintenance in Mobile Wireless Systems

In this paper we analyze periodic maintenance strategies for managing replicated objectsin mobile wireless environments. Under periodical maintenancestrategies, the system periodically checks local cells to determineif a replicated object should be allocated or deallocated in a cell to reduce the access cost.We develop a performance model based on Petri netsthat considers the missing-read cost, write-propagationcost and the periodic maintenance cost with the objective to identify optimal periodic maintenance intervals to minimize theoverall cost. The analysis results show that the overall cost is highwhen the user arrival-departure ratio andthe read-write ratio work against each other and is low otherwise. In all cases, there exists an optimal periodic maintenance interval that would yield the minimum cost.Further, the optimal periodic maintenance interval increases as the arrival-departure ratio andthe read-write ratio work in harmony.     

An Application of Optimal Control Theory to Repairman Problem with Machine Interference

Optimal preventive maintenance policy for a system of machines subject to random breakdowns and repairs is derived using optimal control theory. The optimal policy is shown to be `bang-bang'. The model accounts for the waiting line at the repair facility and establishes a link between machine maintenance and classical repairman problem involving machine interference. An example illustrates the procedure to obtain the optimal preventive maintenance policy. An important feature of this work is that the usual assumption of the steady-state behaviour of the queue is relaxed (by directly considering the Kolmogorov differential equations as state equations of the system) and its transient behaviour is explicitly taken into account.     

A Technique for Optimal Sequential Maintenance Scheduling

This paper presents the mathematical development of, and a simple solution technique for, an optimal sequential maintenance scheduling problem. The model is shown to satisfy the Kuhn-Tucker conditions, the necessary and sufficient conditions for the existence of an optimal solution. Real-world systems consisting of mixtures of constant and increasing failure rate devices are considered in the model. Sequential preventive maintenance schedules are developed for groups of identical items with increasing failure rates. Provision is made for the corrective maintenance of these groups if failures occur in between the preventive maintenance schedules. Also, constant failure rate devices are accorded corrective maintenance when failures occur. Optimality is achieved by minimizing the total annual maintenance cost, subject to constraints on the system availability, number of maintenance personnel and intervals of preventive maintenance. The model is applied to a coal mine power system example.     

An inspection model with minimal and major maintenance for a systemwith deterioration and Poisson failures

A new condition-based maintenance model for a system, subject to deterioration-failures and to Poisson-failures, is presented. After an inspection, based on the degree of deterioration, a minimal maintenance or a major maintenance is performed, or no action is taken. Deterioration failures are restored by major repair; Poisson failures are restored by minimal repair. Major maintenance or major repair restores the system to “good as new” while minimal maintenance restores the system one stage. Generalized stochastic Petri Nets are used to represent and analyze the model, which represents a condition-based maintenance strategy. Based on maximization of the system throughput, an optimal inspection policy within this strategy and optimal inter-inspection time are obtained. The effects of inspection, maintenance and repair parameters are investigated. For a given inspection parameter, a 3-region diagram identifies the effectiveness of an inspection policy based on minimal maintenance, major maintenance, and major repair parameters     

集束型半导体制造设备的预防维修计划优化

研究了生产200mm以上晶圆的半导体制造企业中的主要设备--集束型设备(cluster tools)的预防维修计划优化问题.基于半导体集成电路生产线的复杂性及集束型设备的特点,建立了基于系统观的集束型设备预防维修计划实时优化模型,设计了用遗传算法求解模型的方法,最后以一个实例及运行结果说明了研究的实用性.     

Optimal Availability of Maintainable Systems

Operating a system for optimum availability is a key aspect in many a complex system. Failure of the system can have serious consequences both in monetary terms as well as in loss of production or disruption of service. Optimal control theory provides a convenient tool to obtain the optimal maintenance policies of maintainable systems. These optimal policies are obtained by applying the generalized maximum principle of Gamkrelidze. The prescribed objective function is represented in terms of the cost of repair as well as the downtime cost. The models considered are Markov in that their present state provides sufficient information about the system. Constant as well as time-varying optimal maintenance policies during the planning or operating period can be considered by the proposed method. The optimal maintenance policy very much depends on the failure rates of the individual system components.     

Selective Maintenance Decision-Making Over Extended Planning Horizons

ldquoSelective maintenancerdquo models determine the optimal subset of desirable maintenance actions to perform when maintenance resources are constrained. We analyse a corrective selective maintenance model that identifies which components to replace in the finitely long periods of time between missions performed by a series-parallel system. We formulate this multi-mission problem as a stochastic dynamic program, and compare the resulting optimal infinite-horizon policy to both the optimal single-mission, and two-mission policies by executing a large numerical experiment. Our results indicate that these policies rarely differ, and that when they do, the difference in long-run mission reliability is minimal, which suggests that future work should concentrate on extending results for the single-mission problem.     

Optimal maintenance schedules of systems subject to stochastic failure

Almost all operational and standby systems need maintenance, yet this is often overlooked in the stages of design and development. Lately, maintenance has been emphasized by several factors such as rising costs of labor and material, increased complexity of systems and increased quality requirements. The aim of this paper is to develop new algorithms and analysis techniques that can be used in a general way to handle optimization of various types of inspection and maintenance schedules of systems subject to stochastic failure. Physical problems of systems in active operation with increasing failure rate are treated. Examples of such systems are: airborne electronic equipment, radio receivers, aircraft engines, etc. The optimal maintenance schedule incorporates the effects of inspection, maintenance, delayed detection, uptime and downtime costs. The techniques of classical differential calculus and dynamic programming are applied for the development of the optimal maintenance schedule.