具有常规原因和人为错误的两个不同部件平行系统解的性质

讨论了一个由于常规原因和人为错误引起故障的两不同部件并行系统的模型,修复后的故障系统恢复正常.在假设修复率非常数的前提下,运用纯分析的方法给出了两不同部件并行系统解的性质,绕过了该系统解是否存在的问题.     

由常规故障和临界人为错误引起系统故障的可修复系统的稳定性分析

讨论了一个由两个部件和一个储备部件并且具有临界人为错误和常规故障的随机模型,故障系统修复时间是任意分布的.运用泛函分析的方法,通过分析系统主算子谱特征,给出了系统稳定性的证明.     

在常规故障和临界人为错误条件下具有易损坏储备部件复杂系统的可靠性分析

讨论了一个由两个部件和一个储备部件并且具有临界人为错误和常规故障的随机模型,研究了易损坏部件对系统的影响,故障系统的修复时间是任意分布的.运用泛函分析的方法,通过分析系统主算子的谱特征,给出了系统的可靠性分析的证明.     

故障时间任意分布的两部件可修复系统解的适定性分析

讨论了一个由两个部件并联组成的可修复冗余系统模型,修复后的故障系统恢复如新.在假设修复函数有界的条件下,给出了C_0-半群的生成元(系统算子)对应的柯西问题的解的适定性分析.     

具有备用部件的并联可修复系统稳态解的最优控制问题

针对一种具有两个运行部件和一个储备部件,考虑系统通常故障的发生,且系统故障服从一般分布的人—机系统模型.在Banach空间中,用泛数指标函数作为衡量系统可控的标准,给出了可修复系统最优控制的判别条件.     

具有N个故障模型和一个储备部件的可修复系统的稳定性分析

讨论了一个储备部件和N个故障模型的可修复系统的稳定性.证明系统算子的谱点在复平面的左半平面,虚轴上的点除0点外都无谱,且0是系统算子的一个简单本征值.并由此得出系统模型非负时间依赖解趋于稳定解.     

具有可修储备部件的人-机系统解的特征值分析

针对一种具有两个运行部件和一个储备部件,考虑系统通常故障的发生,且系统故障修复时间服从一般分布的人-机系统模型,对系统的本征值做了进一步分析,并通过具体实例论证了系统非零本征值的存在性,证明了系统本征值与本征向量的一一对应关系.     

由常规故障和临界人为错误引起系统故障的可修复系统动态解的最优控制

研究了由两个运行部件和一个储备部件并且具有常规故障和临界人为错误的随机模型,故障系统的修复时间是任意分布的.先把系统方程的解转化为Volterra 积分方程的形式,证明了系统方程中正解的存在唯一性,再以泛数指标泛函作为衡量系统可控性的标准,研究该系统的最优控制问题.     

可修复人机储备系统最优控制

讨论了一个运行部件和一个储备部件组成的可修复系统的最优控制问题.     

一个备用部件的可修复人机系统的最优控制

讨论了两个运行部件并联和一个储备部件组成的可修复系统的非负解以及系统在某一时刻T的最优控制问题.     

具有热储备的可修复平行系统解的半离散化

针对具有热储备的可修复平行系统模型中修复率U(X)用初等阶梯函数进行逼近,给出了系统的半离散化模型,进一步为数值计算打下了理论基础.     

机器人与其连带的安全装置构成的系统解的半离散化

对机器人与其连带的安全装置构成的系统模型中的修复率μi,i=2,3,4,5用初等阶级函数进行逼近,给出了系统的半离散化模型,进一步为数值计算打下了理论基础.     

具有内部构造安全保障体系的冗余机器系统的解的半离散化分析

对具有内部构造安全保障体系的冗余机器系统中的修复率μ(x)用初等阶梯函数方法进行逼近,并给出了系统的半离散化模型,为进一步数值计算打下基础.     

两不同部件并联可修系统解的半离散化

对两不同部件并联可修系统中的修复率μi(x)进行初等阶梯函数逼近给出了系统半离散化模型,为进一步数值计算打下理论基础.     

具有易损坏储备部件复杂可修系统解的半离散化

讨论了易损坏部件对系统的影响,且故障系统的修复时间是任意分布的.并对修复率μi(x)用初等阶梯函数进行逼近,给出了系统的半离散化模型,为进一步的数值计算打下基础.     

Exact formulation of stochastic EMQ model for an unreliable production system

The purpose of this paper is to present an exact formulation of stochastic EMQ model for an unreliable production system under a general framework in which the time to machine failure, corrective (emergency) and preventive (regular) repair times are assumed to be random variables. For exact financial implications of the lot-sizing decisions, the EMQ model is formulated based on the net present value (NPV) approach. Then, by taking limitation on the discount rate, the traditional long-run average cost model is obtained. The criteria for the existence and uniqueness of the optimal production time in both the models are derived under general failure and specific repair time distributions. Numerical examples are devoted to find the optimal production policies of the developed models and examine the sensitivity of the parameters involved. Computational results show that the optimal decision based on the NPV approach is superior to that based on the long-run average cost approach, though the performance level strongly depends on the pertinent failure and repair time distributions.     

Setting expediting repair policy in a multi-echelon repairable-item inventory system with limited repair capacity

Inventory systems with limited repair capacity are affected by congestion externalities, caused by use of a shared service. There is incompatibility between individual and system optimisation in considering congestion externalities. Three models are described that investigate the congestion effect in a multi-echelon inventory system which has two modes of repair, each with a limited repair capacity. An expanding repair policy employed by the bases in order to choose which repair mode to use is described and compared with different expediting policies related to congestion externalities. The expanding repair policy that considers congestion externalities was found to lead to better system performance measurement than an expanding policy with no congestion. The results of the numerical experiment indicate that the model that ignores congestion externalities—that is, the model that measures each base as an individual—leads to poorer performance measurement for every expediting repair policy, and particularly for the optimal expediting repair policy.     

An optimal replacement policy for a multistate degenerative simple system

In this paper, a degenerative simple system (i.e. a degenerative one-component system with one repairman) with k + 1 states, including k failure states and one working state, is studied. Assume that the system after repair is not “as good as new”, and the degeneration of the system is stochastic. Under these assumptions, we consider a new replacement policy T based on the system age. Our problem is to determine an optimal replacement policy T^∗ such that the average cost rate (i.e. the long-run average cost per unit time) of the system is minimized. The explicit expression of the average cost rate is derived, the corresponding optimal replacement policy can be determined, the explicit expression of the minimum of the average cost rate can be found and under some mild conditions the existence and uniqueness of the optimal policy T^∗ can be proved, too. Further, we can show that the repair model for the multistate system in this paper forms a general monotone process repair model which includes the geometric process repair model as a special case. We can also show that the repair model in the paper is equivalent to a geometric process repair model for a two-state degenerative simple system in the sense that they have the same average cost rate and the same optimal policy. Finally, a numerical example is given to illustrate the theoretical results of this model.     

Optimal system design considering warranty,periodic preventive maintenance,and minimal repair

This paper presents a cost minimisation model for an optimal design of a mixed series-parallel system with deteriorating components. The model incorporates warranty, periodic preventive maintenance, and minimal repair in the design of system configuration. Imperfect repair is adopted to model the effect of preventive maintenance. Both free and pro-rata warranty policies are considered. A numerical example is given to demonstrate the application of this model.     

Optimal age-replacement model with age-dependent type of failure and random lead time based on a cumulative repair-cost limit policy

In this paper, we consider an age-replacement model with minimal repair based on a cumulative repair cost limit and random lead time for replacement delivery. A cumulative repair cost limit policy uses information about a system’s entire repair cost history to decide whether the system is repaired or replaced; a random lead time models delay in delivery of a replacement once it is ordered. A general cost model is developed for the average cost per unit time based on the stochastic behavior of the assumed system, reflecting the costs of both storing a spare and of system downtime. The optimal age for preventive replacement minimizing that cost rate is derived, its existence and uniqueness is shown, and structural properties are presented. Various special cases are included, and a numerical example is given for illustration. Because the framework and analysis are general, the proposed model extends several existing results.