Optimal Design Of Standby Redundant Components For A System Which Has A Mission Of Random Duration

The behavior of an n-component/n-1 cold standby system is analyzed over a horizon whose duration is assumed to be random. Under certain stochastic assumptions concerning the individual components, system performance measures are computed which are applicable for a system that is observed over a random interval of time. Two measures of system performance, expected accumulated uptime and random interval reliability, are used to demonstrate the computational tractability of the modeling perspective proposed in the paper. These measures may be used to optimally choose the number of standby components in the system. Optimization examples are included to illustrate the application of the theory developed.     

考虑预防维修时间及相关性的多部件系统维护策略

针对动车组关键系统维修过程中涉及部件数量多、维修时间长、维修费用高的特点,提出了预防维修时间、故障相关性、经济相关性3重因素影响下的多部件系统机会维护策略。首先对多部件建立部件故障率模型。在此基础上,考虑预防维修时间,将部件层预防维修成本分为独立时间成本和依赖时间成本,对经济相关性进行建模,再以系统维修费用率最小为优化目标建立系统层维护模型,并应用遗传算法求解。最后通过算例表明,相较于考虑单一因素的维修策略,所提维修策略可降低系统维修成本10%及以上,验证了考虑维修时间和部件联合相关性的必要性和有效性。     

Matrix-Flowgraph Methods with Applications to the Analysis of Systems Whose Missions are of Uncertain Duration

A class of semi-Markov models, having applications in operations research and reliability engineering, is examined. The special structure of these models permits their analysis by the inspection of flowgraphs having matrix-valued gains on their branches. The use of such flowgraphs effectively reduces the size and complexity of the state space required for analysis, leading to considerable simplification in both formulation and computation. These flowgraph procedures are presented in the context of reliability and availability analysis for systems whose missions are of uncertain duration, but other areas of application are also noted.     

旧设备租赁的周期预防维护策略优化

针对具有一定年龄的旧设备租赁的特殊性,提出周期预防维护策略。该策略综合考虑设备的年龄、预防维护、小修以及惩罚机制等多种因素对成本的影响,建立以出租方维护成本最小化为目标的周期预防维护模型。经算例分析,研究表明,该方法是有效的,并且在实际维护过程中是易于操作的。     

Imperfect Preventive Maintenance Policy for Complex Systems Based on Bayesian Networks

The main challenge in maintenance planning lies in the realistic modeling of the maintenance policy. This paper is focused on the maintenance optimization of complex repairable systems using Bayesian networks. A new policy is developed for periodic imperfect preventive maintenance policy with minimal repair at failure; this policy allows us to take into consideration several types of preventive maintenance with different efficiency levels. The Bayesian networks are used for complex system modeling, allowing the evaluation of the model parameters. The Weibull parameters and the maintenance efficiency are evaluated thanks to the proposed methodology using Bayesian inference. The approach developed in this paper is applied on a real system, to determine the optimal maintenance plan for a turbo‐pump in oil industry. Copyright © 2016 John Wiley & Sons, Ltd.     

考虑缓冲区库存分配的并联系统预防维护策略研究

为提高并联系统生产过程的连续性,提出了考虑缓冲区库存分配的并联系统(3M1B)预防维护模型。首先,考虑并联系统每台设备的故障率与维护率,在并联系统中上下游设备之间建立缓冲区,构建3M1B系统。其次,考虑设备不完美生产的可能性,以缓冲区库存量与设备运行周期为决策变量,以设备最小生产成本率为目标函数建立预防维护模型,求解最佳的预防维护策略与缓冲区库存分配策略。针对此维护模型,采用离散迭代算法与遗传算法进行求解,并比较了2种算法的优劣,结果表明,对于此模型,离散迭代算法优于遗传算法。最后,通过算例验证模型的可行性和有效性。     

Control Limit Policies for Warranty, Maintenance and Upgrade of Software Systems

Software systems continuously undergo change, mostly in response to customers' needs and expectations, which themselves change from one period to the next. Although the cost of these changes may be many times the original system cost, there is no framework for their analysis and for bringing customers' views into the decision processes. In this paper, we develop a Markov decision process model for warranty, maintenance, and upgrade of software systems, using the index of customer satisfaction as the state variable. We identify optimal and near-optimal policies within the space of control-limit policies     

非线性系统随机振动响应限界极大极小控制

研究非线性系统随机振动的限界极大极小最优控制。引入调控变量放大振动峰响应,用高阶多项式作为性能指标函数,提高其中峰值占比,建立非线性随机振动峰响应的极小化最优控制问题方程;应用随机动态规划原理建立HJB方程,考虑控制作用的有界性,确定半连续与跳变型极大极小最优控制律;最后通过数值结果,说明该最优控制能够有效地抑制非线性随机振动,并调控变量、控制界限、跳变型控制等对于控制效果的影响。     

A Decomposition Method For The Approximate Evaluation Of Capacitated Transfer Lines With Unreliable Machines And Random Processing Times

This paper presents a decomposition method to evaluate the performance measures of a capacitated transfer line with unreliable machines and random processing times. The decomposition is based on approximating the k - 1-buffer system by k - 1 single-buffer systems. Numerical examples indicate that the approach is accurate as long as the probability that a machine is starved and blocked at the same time is small.     

A Bayesian Approach to the Scheduling of Preventive Maintenance

This paper presents a Bayesian model for determining minimum cost rate preventive maintenance schedules where historical data are not available. Also, a model to determine appropriate maintenance budgeting policies is presented and discussed.     

Determination of Preventive Maintenance Lead Time Using Hybrid Analysis

The time for conducting Preventive Maintenance (PM) on an asset is often determined using a predefined alarm limit based on trends of a hazard function. In this paper, the authors propose using both hazard and reliability functions to improve the accuracy of the prediction particularly when the failure characteristic of the asset whole life is modelled using different failure distributions for the different stages of the life of the asset. The proposed method is validated using simulations and case studies.     

异方差随机系数回归模型的最优设计

最优设计方法在工程技术领域和工农业生产中具有广泛的应用．随机系数模型的最优设计研究中通常假定随机误差项具有相同的方差,实际中误差的产生往往与观测点有关,从而具有异方差性质．本文研究一般闭区间设计域上异方差随机系数回归模型的最优近似设计问题．我们获得了最优设计可以在设计域的两个端点处得到的一组充分条件,并进一步证明了当误差项方差具有对称结构且设计域是对称区间时,设计域两个对称端点处的等权重设计同时具有多重最优性质,这时最优设计不依赖于模型中随机误差项的方差结构及随机系数项的方差．     

冷冻机油化验对冷水机组预防性维修的诊断意义

本文介绍了机油化验技术对中央空调预防性维修保养的意义，以及进行机油化验的常见错误，和需要注意的一些事项。     

维修管理模式对制造企业质量控制影响的实证研究

可靠的设备预防维修水平和卓越的产品质量保证能力是保障产品过程质量的关键,现有多数研究集中在质量管理模式与企业绩效的关系分析。在对过程质量控制、设备维修管理评述的基础上,探讨了设备维修管理模式与维修绩效及过程质量控制绩效间的关系。以国内制造企业的连续生产方式为研究对象,运用结构方程模型剖析了RCM、TPM、设备采购管理与和设备维修绩效、过程质量控制绩效的路径关系,发现基础维修管理活动对维修绩效有间接影响,RCM、TPM对设备维修绩效有显著影响,路径系数分别为0.346、0.717,设备维修绩效对过程质量控制绩效的影响显著,路径系数为0922。证明制造企业为提升产品质量,需要完善其设备预防维修系统。     

Determination of Time for Conducting Preventive Maintenance Using Hybrid Analysis

It becomes a common practice to determine time for conducting preventive maintenance (PM) using a hazard function and an alarm limit on a specified failure rate. In this paper, the authors argue that using both hazard and reliability functious can improve the accuracy of the result, especially when the whole-life characteristic failure is modelled using different failure distributions. The PM time predicted bused on the hazard function should be checked against reliability.     

质量管理体系建立与实施维护

运用PDCA工作原理，借鉴ISO 9000族标准的过程方法和管理的系统方法，分析了企业质量管理体系建立与实施维护的基本要求，探讨了基于ISO 9000族标准的质量管理体系建立与实施维护的基本程序，提出了质量管理体系建立与实施维护应经历的策划，实施，检查，处置4个阶段和决策，规划，分析，设计，运行，评定，改进和完善8个步骤。     

维修服务契约的最优设计和分析

本文研究了一个带服务契约的机器维修模型.为了合理优化设计机器维修服务契约,本文利用多服务器排队系统理论对具有多台机器和多个修理工的机器维修模型进行分析,得到了每台机器产生的纯收益和代理商的纯收益期望值;利用非合作博弈论对维修服务契约进行分析,得到了最优保修期、保修费和修理工数目.我们发现最优保修期和修理工数目均与保修价格函数无关.而且,对于固定寿命的机器,机器总数几乎不影响最优保修期的设定.     

随机结构系统的特征值和特征向量分析

从实际工程出发，以现代数学理论为依据，研究了随机结构系统的特征值问题。根据Kronecker代数、向量值和矩阵值函数的灵敏度、一般二 阶矩法和概率摄动技术给出了计算随机结构系统特征值和特征向量的数值方法，可以有效和可靠地得出随机结构系统的特征值和特征向量的统计量。     

基于可靠度限制的周期性预防维护模型研究

实施周期性的预防维护可以减缓设备的老化速度,进而增加设备的使用寿命.考虑设备经维护后会改善的情况.提出并构建了一个改善因子模型,以此描述设备维护改善的效果,该改善因子模型综合考虑了预防维护成本、设备年龄以及维护过程学习效应等因素影响.在改善因子模型基础上,基于无限时间域的概念,构建了包含预防维护成本、最小修复成本、置换成本等在内的成本函数.在可靠度限制下,推导出了单位时间成本函数和最佳维护时间间隔的计算模型,给出了计算最佳参数的流程.最后,进行了实例分析.     

An Analysis of Scheduling Policies In Multiechelon Production Systems

Results of a simulation study of the economics of frequency of rescheduling Material Requirements Planning (MRP) systems are presented for a single-product, two-stage system in which demand is uncertain. The results indicate that for systems with moderate demand uncertainty, frequent rescheduling to maintain customer service may be uneconomical when compared with the alternative of more stable schedules in conjunction with safety stock. This result arises primarily because the cost of “emergency” production setups which occur when rescheduling is frequent exceeds the cost of safety stock required to “protect” stable schedules.