论文总字数：22192字

摘 要

关键词：串并联系统；缓冲库存；蒙特卡洛仿真；维修决策

Optimal maintenance of a series production system with several intermediate buffers

Abstract: Maintenance policies are of great importance in a production system because of their contribution to safety and economics of plants operation. Intermediate buffers often exist in practical series production systems. They can reduce the influence of the breakdown and maintenance of subsystems on the system production rate. At the same time, the effects of intermediate buffers also make it more difficult to modelling the degradation process of the system When the condition of a system, such as its degradation level, can be continuously monitored, a Condition-Based Maintenance (CBM) policy can be implemented, according to which the decision of maintaining the system is taken dynamically on the basis of the observed condition of the system. In this paper, we consider a continuously monitored system with three multi-component subsystems and two intermediate buffers and a CBM policy is adopted in this system. The problem is framed as a single objective search aiming at the average total cost during unit time, determine the optimal degradation level beyond which preventive maintenance has to be performed. For a closer adherence to reality, the predictive model describing the evolution of the degrading system is based on the use of Monte Carlo (MC) simulation. After the optimization of maintenance strategy, this paper researches the effect of the cost parameters on objective function. The buffer capacity can reduce the total cost in a way. At last by setting different maintenance degradation threshold level for different buffer levels, this paper verifies if buffer levels impact the determination of maintenance strategy. With genetic algorithm, the optimal maintenance policy is found. It is found that buffer level doesn’t have an obvious effect because the objection function of the new maintenance policy doesn’t seem better than that of previous maintenance policy.

Key words: Series-parallel system；Intermediate buffer；Monte Carlo simulation；Maintenance policy

目 录

1.绪论 1

1.1研究背景与意义 1

1.2研究现状 1

1.2.1相关文献 2

1.2.2蒙特卡洛仿真 2

1.2.3遗传算法 3

1.3论文研究内容及结构安排 4

1.3.1研究内容 4

1.3.2结构安排 4

2.问题描述 5

2.1基本问题描述 5

2.1.1生产系统 5

2.1.2控制变量 5

2.1.3目标函数 5

2.2基本假设 6

3.系统建模 7

3.1模型建立 7

3.1.1整体模型 7

3.1.2维修模型 7

3.1.3劣化模型 7

3.2蒙特卡洛模型 8

3.3在遗传算法中嵌入蒙特卡洛模型 8

3.4参数设置 9

4.仿真过程 11

4.1仿真总体流程图 11

4.2获得下一时刻系统状态 12

4.2.1获取维修状态向量 12

4.2.2获取下一时刻各元件劣化状态 13

4.2.3计算库存水平变化 13

5.仿真实验 16

5.1视情维修仿真实验 16

5.1.1穷举法寻优 16

5.1.2以最优解为中心分析各项成本 17

5.1.3库存容量对实验结果影响 17

5.1.4敏感性分析 19

5.2结合实时库存水平的视情维修仿真实验 20

6.结论和展望 22

6.1结论 22

6.2展望 22

致谢 22

参考文献： 23

包含多个缓冲库存的串并联系统维修决策优化研究

1.绪论

1.1研究背景与意义

维修是一个被学术界、工程界和企业界广泛关注的领域。在学术界，国际上每年仅维修运筹学方面就有数以百篇计的学术论文发表。维修对于各类工业生产设备、军事装备以及交通运输工具等系统的正常工作或安全运行具有重要作用。维修费用也是各类企业的主要支出之一。在工程界，随着各类工程系统安全性、可靠性和经济性要求的不断提高，维修已与设计、制造互补，是全寿命期正常使用的基本保障。产生了以可靠性为中心的维修，维修指导小组的维修指导思想，全员生产维修，以商业为中心的维修等重要的工程化的维修理论。在企业界，维修不但是企业经济地、安全可持续地进行生产活动的基本保障，也是提高生产效率和生产质量、降低企业成本的主要途径之一。

包含多个缓冲库存的串并联系统在实际生产中广泛存在。一般，一条生产线会由多种不同分工的生产环节构成，而为了保证各个子系统的生产效率，通常这些子系统会由一些相同的部件并联。在这些生产环节之间，会设置一些缓冲库存。当上游子系统由于维修而停止生产的时候，这些缓冲库存可以减少其对下游生产的影响。不过，缓冲库存的存在也使得生产系统的建模变的更加复杂。

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