Integrating noncyclical preventive maintenance scheduling and production planning for a single machine

This paper deals with the problem of integrating noncyclical preventive maintenance and tactical production planning for a single machine. We are given a set of products that must be produced in lots during a specified finite planning horizon. The maintenance policy suggests possible preventive replacements at the beginning of each production planning period, and minimal repair at machine failure. The proposed model determines simultaneously the optimal production plan and the instants of preventive maintenance actions. The objective is to minimize the sum of preventive and corrective maintenance costs, setup costs, holding costs, backorder costs and production costs, while satisfying the demand for all products over the entire horizon. The problem is solved by comparing the results of several multi-product capacitated lot-sizing problems. The value of the integration and that of using noncyclical preventive maintenance when the demand varies from one period to another are illustrated through a numerical example and validated by a design of experiment. The later has shown that the integration of maintenance and production planning can reduce the total maintenance and production cost and the removal of periodicity constraint is directly affected by the demand fluctuation and can also reduce the total maintenance and production cost.     

On a general periodic preventive maintenance policy incorporating warranty contracts and system ageing losses

In this paper, a general periodic preventive maintenance (PM) policy for a repairable revenue-generating system is developed and studied. We define ‘ageing losses’ as the difference in revenues generated by an ideal system (no ageing) and a real system that ages over the same period of consideration. It is assumed that preventive maintenance slows the system deterioration process and therefore reduces ageing losses. The proposed model is general in the sense that (1) both the warranty contracts and system ageing losses are incorporated in the maintenance cost modeling and (2) the implementation of PM actions does not have to be strictly periodic. A cost model is developed for the buyer under two decision variables—the calendar time of the first PM and the degree of each PM. Numerical examples are then presented to show the effectiveness of the proposed model. Sensitivity analyses are further conducted to investigate the impact of model parameters on optimal solutions.     

Production planning of a hybrid manufacturing-remanufacturing system under uncertainty within a closed-loop supply chain

This paper deals with the production planning and control of a single product involving combined manufacturing and remanufacturing operations within a closed-loop reverse logistics network with machines subject to random failures and repairs. While consumers traditionally dispose of products at the end of their life cycle, recovery of the used products may be economically more attractive than disposal, while remanufacturing of the products also pursues sustainable development goals. Three types of inventories are involved in this network. The manufactured and remanufactured items are stored in the first and second inventories. The returned products are collected in the third inventory and then remanufactured or disposed of. The objective of this research is to propose a manufacturing/remanufacturing policy that would minimize the sum of the holding and backlog costs for manufacturing and remanufacturing products. The decision variables are the production rates of the manufacturing and the remanufacturing machines. The optimality conditions are developed using the optimal control theory based on stochastic dynamic programming. A computational algorithm, based on numerical methods, is used for solving the optimal control problem. Finally, a numerical example and a sensitivity analysis are presented to illustrate the usefulness of the proposed approach. The structure of the optimal control policy is discussed depending on the value of costs and parameters and extensions to more complex reverse logistics networks are discussed.     

Case Study: Model for Economic Lifetime of Drilling Machines in the Swedish Mining Industry

The purpose of this article is to develop a practical economic replacement decision model to identify the economic lifetime of a mining drilling machine. A data-driven optimization model was developed for operating and maintenance costs, purchase price, and machine resale value. Equivalent present value of these costs by using discount rate was considered. The proposed model shows that the absolute optimal replacement time (ORT) of a drilling machine used in one underground mine in Sweden is 115 months. Sensitivity and regression analysis show that the maintenance cost has the largest impact on the ORT of this machine. The proposed decision-making model is applicable and useful and can be implemented within the mining industry.     

Lockout/tagout and operational risks in the production control of manufacturing systems with passive redundancy

This paper addresses problems associated with production control and occupational safety in a manufacturing system prone to failure involving two machines working in passive redundancy. Machines turning out one part experience two modes of failure and repair: firstly, where failure occurs when a machine remains in fair condition; and, secondly, where such failure results in outright breakdown. Accordingly, we examine both modes of failure for their impact on a flexible manufacturing system (FMS) with respect to production control in terms of costs associated with lockout/tagout procedures and corrective maintenance. This study seeks to identify optimal costs related to backlogs, inventories and maintenance over an infinite planning horizon, along with levels of occupational risk where production control includes efficient planning of lockouts/tagouts. Our study offers numerical methods which may be employed to achieve optimal conditions in setting control policies. A numerical example and sensitivity analysis support this approach.     

基于RPN和多粒度语言集结系统的多状态退化系统故障分析

针对传统故障分析方法缺乏系统性的问题,以多状态退化系统为研究对象,引入风险优先数(RPN),借助多粒度语言评价集结系统,提出了一种新的多状态退化过程的评估方法。明晰了系统退化过程的关键环节和关键参量,更加全面地分析故障演变过程。以系统风险加权后的最低维修费用为目标,运用策略迭代算法,计算出不同故障状态下的最优维修策略。以算例说明故障分析过程,验证了所提方法的有效性和实用性。     

Production planning and inventory allocation of a single-product assemble-to-order system with failure-prone machines

We consider the optimal production and inventory allocation of a single-product assemble-to-order system with multiple demand classes and lost sales. Each component is replenished by a dedicated machine that is subjected to unpredictable breakdowns. We find that the machine state not only influences the production and allocation decisions on its own component but also influences the decisions on the other components. Specifically, the optimal component production policy is a base-stock policy with the base-stock level non-decreasing in the inventory levels of the other components and the states of the other machines. The optimal component allocation policy is a rationing policy with the rationing level non-increasing in the inventory levels of the other components, the states of the other machines, and its own machine state. We use an exponential distribution to approximate the distribution of the total processing times and propose two heuristic policies to address the production and allocation decisions. The importance of taking machine failures into consideration is revealed through computational experiments.     

Integrated product specifications and productivity decision making in unreliable manufacturing systems

This paper considers joint production control and product specifications decision making in a failure prone manufacturing system. This is with the knowledge that tight process specifications, while leading to a product of more reliable quality and higher market value, are at the same time associated with higher levels of non-conforming parts, a higher rate of parts rejection and thus a lowering of overall plant productivity. The decision making is further complicated by the lack of reliability of the production process, which imposes that an adequate, also to be designed, level of inventory of finished parts be maintained. The overall optimal decision policy is defined here as one that maximizes the long term average per unit time profit of a combined measure of quality and quantity dependent sales revenue, minus inventory and backlog costs, in the presence of random plant failures and random repair durations. Policy optimization is achieved via a revisited model of the Bielecki–Kumar theory for Markovian machines and a simulation and experimental design based methodology for the more general cases.     

A production rate control policy for stochastic repair and remanufacturing systems

We consider the control of a manufacturing system responding to planned demand at the end of the expected life of each individual piece of equipment and unplanned demand triggered by a major equipment failure. The difficulty of controlling this type of production system resides in the variable nature of the remanufacturing process. In practice, remanufacturing operations for planned demand can be executed at different rates, referring to different component replacement and repair strategies. We formulate this problem as a multi-level control problem and propose a suboptimal control policy. The proposed control policy is described by inventory thresholds triggering the use of different execution modes. Determination of the control policy parameters is based on parameter optimization of analytical cost expressions. A numerical example based on a real case is presented. Our analysis demonstrates that the use of the proposed control approach can lead to a significant reduction in the total average cost, as compared to current practices.     

The effects of a free-repair warranty on the discrete-time periodic replacement policy

This paper presents the effects of a free-repair warranty on a periodic replacement policy with a discrete time process. Considering a repairable product that should be operational at the time over an indefinitely long operation cycle n (n=1, 2, …), under the discrete-time periodic replacement policy, a product is preventively replaced at pre-specified operation cycles N, 2N, 3N, … (N=1, 2, …). When the product fails, a minimal repair is performed at the time of failure, and the failure rate is not disturbed by each repair. The cost models from the customers' perspectives are developed for both warranted and non-warranted products. The corresponding optimal replacement period N? is derived such that the long-run expected cost rate is minimized. Under the assumption of the discrete time increasing failure rate, the existence and uniqueness of the optimal replacement period are shown, and the impact of a free-repair warranty on the optimal periodic replacement policies is investigated analytically. The optimal N* for a warranted product should be adjusted toward the end of the warranty period. Finally, numerical examples are demonstrated for the optimal policy illustration and verification. The observations from the numerical results provide valuable information for a buyer (user) to adjust the optimal periodic replacement policy if a product is operating in discrete time under a free-repair warranty.     

基于失效风险的建筑物预防维修成本模型优化

建筑物预防性维修成本的最优控制问题,是企业现代化经营管理的一个重要组成部分,直接影响到企业的经济效益。针对承受重复荷载作用的建筑构件,失效概率随服役时间增加而增大的实际情况,提出了失效风险的概念。采用役龄回退因子描述了维修后失效概率降低的程度,在此基础上推算出满足可靠度约束条件,适用于特定时间段非等间隔检测期序列,计算出单位维修周期内的检测次数。通过对维修成本函数的分析,建立了基于等失效风险状态的维修成本优化模型。为房屋物业管理部门进行建筑物的维修和更换决策提供参考依据。     

Modelling quality in replacement and inspection maintenance

Heterogeneity in component and maintenance quality is considered in the context of age-based inspection and replacement for a single component system. A three-state component failure model is assumed, with a defective state preceding the failed state. Heterogeneity in maintenance intervention is modelled by supposing that inspections may induce the defective state. Component heterogeneity is modelled by supposing that the population of components comprises a mixture of the weak and strong, and that the mixing proportion and cost of components vary between suppliers. Within this framework, the impact, on system reliability and cost, of switching component or maintenance supplier is determined. Broadly, our finding is that one is much more inclined to switch supplier in order to obtain higher quality maintenance than to obtain higher quality components. A gas pressure control valve is used to illustrate our ideas.     

Optimizing capital investments under technological change and deterioration: A case study on MRI machine replacement

ABSTRACT

We study the multiple style and type parallel asset replacement problem (MST-PRES), which determines an optimal policy for keeping or replacing a group of assets that operate in parallel under a limited budget. Operating assets generally suffer from deterioration, which results in high operation and maintenance (O&M) cost and decreased salvage value, and technological improvements make it possible for new assets to operate more efficiently at a lower cost. In order to address these issues, we formulate a multi-objective mixed-integer programming (MIP) model that minimizes fixed and variable costs of purchasing new assets, O&M cost, inventory cost, and penalty cost for unmet demand minus salvage values, while considering technological advances and deterioration as a gain and loss in capacity, respectively. We apply our model to a case study involving two different styles of assets: a full-body magnetic resonance imaging (MRI) machine and a smaller extremity magnetic resonance imaging (eMRI) machine. Each has two types: high-field and low-field. We perform computational experiments and analyses using key model parameters and illustrate optimal replacement strategies considering the impact of technological advances and deterioration. Results show that the proposed MIP model provides valuable insights and strategies for companies, decision makers, and government entities on the capital asset management.     

Establishing Maintenance Resource Levels Using Selective Maintenance

We address the performance of a repairable system that is required to perform a sequence of equally spaced, identical missions with breaks between missions. The system is series-parallel in structure, and component repair can only be performed during breaks between missions. Due to limitations on maintenance resources, it may be impossible to make all necessary repairs before the next mission. Such situations require the use of selective maintenance, the process of identifying the subset of maintenance actions to perform from a set of desirable maintenance actions. We build upon previous research in selective maintenance by addressing decisions related to establishing capacities for the limited maintenance resources. We model mission-to-mission changes in maintenance resource capacity, and we develop a methodology for establishing constant resource capacities for a sequence of missions. Finally, we develop a methodology for integrating redundancy allocation and maintenance resource allocation decisions.     

Application of fuzzy decision making in part-machine grouping

In this study, fuzzy set theory (FST) is used to set out the cell layout. A new algorithm which will consider both design and manufacturing attributes and operation sequences as factors, is proposed to formulate the problem. The structure of the algorithm is based on fuzzy decision making system (FDMS). Hence three factors mentioned above are determined as input variables and fuzzified using membership function concept. Then the pairwise comparison of the analytical hierarchy process (AHP), which ensures the consistency of the designer`s decisions when assigning the importance of one factor over another, is used to find the weights of these factors. Applying IF–THEN decision rules, parts relationship chart (PRC) is generated. After these steps, the traditional cell formation procedure is applied. Finally the proposed method is scored by performance measures such as machine investment, the amount of work load deviations within cell and between cells and the number of skippings. Also the comparison with Aktürk's study (International Journal of Production Research 34 (8) (1996) 2299–2315) in respect to these performance measures is presented.     

Restraints of trade by durable good producers

Whether they face competition or not, durable good producers may have an incentive to impose vertical restraints on their customers in order to protect quasi-rents in the aftermarkets for maintenance and repair. In this paper, we show that these vertical restraints have little to do with the usual antitrust concerns regarding tying arrangements. Nonetheless, imposing such restraints involves antitrust risks. We examine these risks and the associated antitrust policy questions in light of the Supreme Court's recent Kodak decision. We also offer some suggestions for the appropriate antitrust policy.     

机械“医生”彭兴礼的“另类”生意

彭兴礼年轻时走过一段隧道,一条几公里长的铁路隧道：刚进隧道时,还能看到身后的光亮,渐渐地,身后的光亮成了一个点,然后是无边的黑暗。那时候他喜欢武术,包里有副二节棍,为了不撞到墙,他把棍拿出来,划着墙壁往前走。没有人,什么都没有。他就这样一直走着,走出隧道时,棍已经被磨平了半面。     

The Impact of Collective Bargaining Legislation on Strike Activity and Wage Settlements

We examine the effects of collective bargaining legislation, such as (among others) bans on replacement workers and reinstatement rights, on private sector strike activity and wage settlements using Canadian data from 1978 to 2008. Our estimates indicate that this legislation does not have a statistically significant effect on the incidence of strikes. However, we do find that some of the policy variables have a statistically significant effect on strike duration and wage settlements.     

失效模式相关时石油钻采机械的可靠性计算

介绍了任意失效模式相关时石油钻采机械系统或零、部件可靠度计算模型。并利用极限状态方程给出了在变量相关、失效模式相关时可靠度计算的一般公式,以及对于非正态变量的转换处理方法,并结合实例进行了计算。     

Short term financial success in large business organizations: The environment-strategy connection

This study examines the interrelationships of environmental changes and strategic action variables with each other and with short term success, for 358 large business firms over a 45 year period. Success (Fortune ratings and ROA) is found to be related to two strategic decision segments. Several strategy-environment relationships are also found. Some methodological problems are noted in the attempt to move policy research from case analysis to statistical explanation.