A SIMULATION OF INTERACTIVE MAINTENANCE DECISIONS

In this day of automation, effective maintenance decisions are a legitimate concern. This paper broadens the traditional concept of maintenance to include any policies which tend to reduce the frequency or severity of failures. A simulation model is used to demonstrate the inter-relatedness of multiple maintenance policies for a truck depot. It is demonstrated that the proper selection of a maintenance policy set should consider the variability of the system outputs due to the daily dynamics, as well as the transient behavior of the system. It is also shown that the choice of an appropriate maintenance policy should recognize the distribution of total annual costs and should not base the analysis solely upon average total annual costs.     

具有隐藏故障的多状态竞争失效系统检测策略研究

复杂工业系统的故障中有40%属于隐藏故障,若隐藏故障得不到及时消除,则可能导致巨大的经济损失。本文针对具有隐藏故障的多状态竞争失效系统,在考虑不完全检测的基础上,对其进行了维修建模。首先,基于制定的视情维修策略,分析了系统的更新情形;然后,基于所推导出的各种系统更新情形的发生概率,建立了以期望成本率为目标函数,以检测间隔时间为决策变量的维修模型。最后,以电容器组为例对所构建维修模型的适用性和有效性进行了验证,研究结果表明,检测质量对检测策略的制定有重要影响,因此研究具有隐藏故障的多状态竞争失效系统的检测策略时,有必要考虑检测误差。本文提出的维修建模方法不仅能在一定程度上丰富多状态竞争失效系统的维修策略理论与方法,还能为工程实际中复杂工业系统的维修工作提供理论基础与决策依据。     

Joint modified block replacement and production/inventory control policy for a failure-prone manufacturing cell

This paper considers a joint preventive maintenance (PM) and production/inventory control policy of an unreliable single machine, mono-product manufacturing cell with stochastic non-negligible corrective and preventive delays. The production/inventory control policy, which is based on the hedging point policy (HPP), consists in building and maintaining a safety stock of finished products in order to respond to demand and to avoid shortages during maintenance actions. Without considering the impact of preventive and corrective actions on the overall performance of the production system, most authors working in the reliability and maintainability domains confirm that the age-based preventive maintenance policy (ARP) outperforms the classical block-replacement policy (BRP). In order to reduce wastage incurred by the classical BRP, we consider a modified block replacement policy (MBRP), which consists in canceling a preventive maintenance action if the time elapsed since the last maintenance action exceeds a specified time threshold. The main objective of this paper is to determine the joint optimal policy that minimizes the overall cost, which is composed of corrective and preventive maintenance costs as well as inventory holding and backlog costs. A simulation model mimicking the dynamic and stochastic behavior of the manufacturing cell, based on more realistic considerations of the real behavior of industrial manufacturing cells, is proposed. Based on simulation results, the joint optimal MBRP/HPP parameters are obtained through a numerical approach that combines design of experiment, analysis of variance and response surface methodologies. The joint optimal MBRP/HPP policy is compared to classical joint ARP/HPP and BRP/HPP optimal policies, and the results show that the proposed MBRP/HPP outperforms the latter. Sensitivity analyses are also carried out in order to confirm the superiority of the proposed MBRP/HPP, and it is observed that for practitioners, the proposed joint MBRP/HPP offers not only cost savings, but is also easy to manage, as compared to the ARP/HPP policy.     

Milton keynes: A model for regenerating our cities?

Milton Keynes is one of the most succesful of Britain's new towns. With new towns such as Peterborough and Telford, this can be seen as the latest stage of the New Town Movement which started at the end of World War II. Of these new towns, Milton Keynes is the largest and the most ambitious in its objectives. The problems facing the United Kingdom today are very much greater than when Milton Keynes was first started but, because of a flexible planning approach, the Development Corporation has responded to these changes and has established policies to assist in solving these problems. The key to this success is a more flexible and effective manufacturing base. Today we face unprecedented changes, unique in our history. Although manufacturing and services will provide the wealth to solve these problems, we will only succeed through co-operation between the private sector and local and national government. A study of Milton Keynes, its growth, objectives, successes and failures could provide a useful model for our future planning.     

考虑故障停机的生产控制与维修计划联合决策模型

通过生产控制与维修计划协同决策,降低生产成本。首先描述生产过程,分析各项费用。其次,建立了考虑生产过程失控、故障率和故障停时间的生产过程控制、生产计划优化和维修管理联合优化决策的模型。通过模型求解,联合制定出生产过程检查策略、生产计划（经济生产批量、生产批次）以及维修计划（PM间隔期）,实现单位时间内总费用最低的目标。再次,案例研究,分析生产过程失控、故障率和故障停机时间对于经济生产批量、生产过程检查策略和生产系统维修计划的影响。该模型从理论上解决了生产过程控制、生产计划优化和维修管理联合优化决策难题,对于指导企业制定生产计划和生产系统的检修计划,进而提高产品质量、降低生产成本、确保准时交货都具有指导意义和实用价值。     

GUIDELINES FOR IMPLEMENTING PREDICTIVE MAINTENANCE*

Recent advances in predictive maintenance technologies have led many manufacturers to abandon traditional periodic maintenance policies and replace them with predictive maintenance policies. The models in this paper explicitly evaluate the decision to utilize both predictive and periodic maintenance when the objective is to minimize expected maintenance costs per unit time. Renewal theory is used to obtain optimal policies as unique solutions of integral equations that depend on the failure distribution and prediction capabilities. Based on this research, we recommend that practitioners do not abandon the traditional maintenance methods but follow our guidelines for utilizing periodic maintenance in conjunction with the new technologies.     

基于时间延迟理论的预防维修模型及案例研究

本文旨在解决设备维修决策过程中预防维修检查数据缺乏情况下如何确定出合理的维修间隔期问题。首先,通过预防维修技术经济分析,提出了有关维修间隔期和总的停机时间之间关系的预防维修模型。其次,根据时间延迟维修理论,利用故障记录数据和预防维修检查数据的估计值,建立了统计模型并用来计算维修间隔期内故障次数的期望值。计算机仿真检验证明统计模型正确后,采用最大拟然法估计有关参数,这些参数包括缺陷发生率、时间延迟分布、检查出缺陷的概率等。最后是案例分析,应用估计参数和预防维修模型,计算出最佳的维修间隔期。     

基于期望效益的随机检修系统决策模型研究

本文研究了一类带检修退化可修系统的维修策略问题,为提高系统的安全性和可靠性,在系统故障前增加了随机检修,并在此种情况下对维修模型进行了研究。在假定系统检修"修复如旧"、系统逐次故障后的维修时间构成随机递增的几何过程和系统逐次故障后的工作时间构成随机递增的几何过程的情况下,选择系统的故障次数N为更换策略,利用单调的几何过程,求出了系统经长期运行单位时间内的期望效益的表达式.最后通过数值例子对所得结果进行了分析。     

碳税政策下闭环供应链网络均衡分析

针对由多个制造/再制造工厂和多个需求市场构成的闭环供应链网络，考虑两种碳税政策：单一比例碳税政策和超额累进碳税政策，分别量化两种碳税政策下工厂需支付的碳税，分析两种碳税政策下闭环供应链网络各成员企业的均衡条件，建立闭环供应链网络均衡模型，提出修正投影算法求解模型，最后，通过算例，对比分析两种碳税政策对闭环供应链网络成员企业新产品产量、网络间正向/逆向产品交易量、需求、价格、减排投资、碳排放量、碳税及成员利润的影响。     

Measuring dynamic efficiency of highway maintenance operations

In this paper we discuss a dynamic efficiency measurement model for evaluating the performance of highway maintenance policies where the inter-temporal dependencies between consumption of inputs (i.e., maintenance budget) and realization of outputs (i.e., improvement in road condition) are explicitly captured. We build on a micro representation of pavement deterioration and renewal processes and study the impact of the allocation of scarce maintenance budgets over time. We provide a measure of efficiency that contrasts the optimized budget allocations to the actual ones. The developed model is then applied to an empirical dataset of pavement condition and maintenance expenditures over the years 2002 to 2008 corresponding to seventeen miles of interstate highway that lay in one of the counties in the state of Virginia, USA. The policies that were found through optimization showed that road authorities should give higher priorities to preventive maintenance than corrective maintenance. In essence, by applying preventive maintenance, the road authorities can effectively decrease the need for future corrective maintenance while spending less overall.     

ROBUSTNESS OF VARIOUS PRODUCTION CONTROL POLICIES IN SEMICONDUCTOR MANUFACTURING

This paper compares several different production control policies in terms of their robustness to random disturbances such as machine failures, demand fluctuations, and system parameter changes. Simulation models based on VLSI wafer fabrication facilities are utilized to test the performance of the policies. Three different criteria, namely, the average total WIP, the average backlog, and a cost function combining these measures, are used to evaluate performance. Among the policies tested, the Two‐Boundary Control policy outperforms the others.     

Managing AMI in a Just-In-Time Environment in the UK and Japan

In recent years many commentators have addressed the ‘crisis’ in manufacturing industry (Gerwin, 1982; Drucker, 1988, 1990; Hayes and Jaikumar, 1988). Some have offered cross-national comparisons on Japanese and Western management methods and techniques (Kharbanda and Stallworthy, 1991; Oliver and Wilkinson, 1987; Pascale and Athos, 1981) whilst others have concentrated on improving performance in specific fields such as management accounting (Kaplan, 1984; Cooper, 1991) or manufacturing management (Schonberger, 1982; Halt, 1983). Empirical research into managing AMT in Japan and the UK (Currie 1991a) considers some of the broader managerial issues in manufacturing. Cultural differences are common in the areas of investment appraisal, post-auditing of AMT and preventive maintenance policy. For example, in Japan JIT is perceived ‘holistically’ incorporating production management, total quality assurance (TQA) and total preventive maintenance (TPM). This is contrary to the UK in that many large manufacturing companies fail to include TPM in their manufacturing strategies (Currie and Seddon, 1991). There are few management information systems (MIS) which provide an understanding of machine performance using both non-financial and financial information. Focusing on maintenance as a central theme, the paper discusses the development of the Failure And Scheduled Maintenance Analysis (FASMA) system, which offers a practical solution to the problem of collecting and manipulating manufacturing data on the shopfloor (Seddon, 1991a). Essentially, FASMA attempts to interface both the manufacturing and management accounting functions by translating machine performance data into valuable information from which preventive maintenance policy may be improved. Using FASMA to measure machine performance at a major UK automotive manufacturer, machine down-time has averaged 61% each month over a 3-year period. By manipulating this data, performance measurement information may be utilized by management accountants. FASMA thus develops a link between manufacturing and management accounting by providing data on machine performance which can be used for cost analysis within a manufacturing environment. The paper concludes by arguing that manufacturing strategies can only be developed using appropriate management information systems (MIS) designed to enhance functional integration. This will enable a better understanding of how the ‘manufacturing jigsaw’ fits together.     

基于I-O与SVAR模型的制造业完全能耗强度影响因素研究

改革开放以来,制造业完全能耗强度尽管总体呈下降趋势,但与发达国家相比,仍处于高位。本文考虑了制造业隐含能源消耗,基于投入产出法构建了制造业完全能耗强度测度公式,并基于WSR方法论构建了制造业完全能耗强度影响因素体系,运用SVAR模型探究1980-2016年各因素对制造业完全能耗强度的影响规律。结果表明,在短期内,企业规模、产业结构、能源价格、技术进步、FDI等对制造业完全能耗强度影响程度相对较大。企业平均规模与重工业占比、技术进步率上升,制造业完全能耗强度下降;而能源价格、FDI上升,制造业完全能耗强度上升。中长期内,企业规模、产权结构、能源价格、产业结构、技术进步等对制造业完全能耗强度影响程度相对较大。能源价格、国有企业占比、技术进步率上升,制造业完全能耗强度先降后升;企业平均规模、重工业占比上升,制造业完全能耗强度先升后降。适度扩大企业规模,合理调控能源价格,推进产权结构多元化等对降低制造业完全能耗强度贡献相对突出。     

Adoption and Termination of Employee Involvement Programs

Using an interview survey of manufacturing establishments that provide 10 years of retrospective data on labor practices, we investigate factors associated with the adoption and termination of employee involvement programs and the relation between these and other human resource policies. In the period studied, more firms introduced than terminated such programs but a sufficiently large number chose to eliminate such programs to indicate that employee involvement does not fit in all business settings. Our results show that business strategy and the use of other complementary human resource policies affect the dynamics of employee involvement use in US manufacturing establishments.     

A Study of Labor Allocation Strategies in Cellular Manufacturing

Current research studies in cellular manufacturing have considered environments constrained only by the machine resource, when in fact the flexibility of manufacturing cells is derived mainly from its allocation of the labor resource. This research specifically examines the labor resource in cellular manufacturing, also known as group technology (GT), through a series of simulation experiments on a hypothetical GT shop and recommends conditions under which different labor allocation strategies may be appropriate. The effects of various product routings and scheduling policies on labor allocation are also examined.     

Burn-in Time and Estimation of Change-Point with Weibull-Exponential Mixture Distribution*

Many industrial products have three phases in their product lives: infant-mortality, normal, and wear-out phases. In the infant-mortality phase, the failure rate is high, but decreasing; in the normal phase, the failure rate remains constant; and in the wear-out phase, the failure rate is increasing. A burn-in procedure may be used to reduce early failures before shipping a product to consumers. A cost model is formulated to find the optimal burn-in time, which minimizes the expected sum of manufacturing cost, burn-in cost, and warranty cost incurred by failed items found during the warranty period. A mixture of Weibull hyperexponential distribution with shape parameter less than one and exponential distribution is used to describe the infant-mortality and the normal phases of the product life. The product under consideration can be either repairable or non-repairable. When the change-point of the product life distribution is unknown, it is estimated by using the maximum-likelihood estimation method. The effects of sample size on estimation error and the performance of the model are studied, and a sensitivity analysis is performed to study the effects of several parameters of the W-E distribution and costs on the optimal burn-in time.     

Shopfloor control practices in three Pacific basin countries: a comparative view of small machine tool industry

The strategic importance of manufacturing decisions to the competitive position of a firm is well known. As the sphere of competition has expanded from regional to national to international, successful manufacturing decisions have become ever more complex. The success of manufacturing strategics ultimately rests on proper tactical implementation at the shopfloor level. In order to explore various operating policies and procedures at a basic level, and to contrast them with some commonly held beliefs, this paper examines and compares the shopfloor practices of companies in the small machines too! industry in selected countries in the Pacific rim, namely; Japan,

China and South Korea. While many popular views on manufacturing practices in these countries are supported by the study, the results challenge other commonly held views.     

Enterprise Ownership, Market Competition and Manufacturing Priorities in a Sub-Saharan African Emerging Economy: Evidence from Ghana

The economic liberalization policies being implemented by many African economies have led to significant efficiency and performance improvements in the activities of privately owned enterprises. This study examines the effect of the economic liberalization policies on the entrepreneurial development of domestic-owned enterprises. This is done by examining how the type of enterprise ownership (wholly domestic-owned enterprises vs. foreign–domestic joint ventures enterprises), and the increase in competition affect the manufacturing priorities of privately owned enterprises in Ghana. The results show that the enhancement in manufacturing efficiency and quality improvement in privately owned enterprises could be traced to the activities of foreign–domestic joint venture enterprises. However, as market competition increases, wholly domestic-owned enterprises emphasize manufacturing efficiency and quality improvement more that foreign–domestic joint venture enterprises. Implications for policy are discussed.     

Examining the Impact of Speed of Quality Improvement on Quality-Related Costs

The Fine (1986) quality-based learning curve model is extended to include the consideration of speed of quality improvement. The model demonstrates that under different circumstances rapid quality improvement effects are either beneficial or detrimental to improvement in quality-related costs. Hypotheses are developed from the analysis of this speed of quality improvement model. The hypotheses are tested in an automotive parts manufacturing company with five similar plants. Results show that with an increase in the speed of quality improvement, the rate of growth in prevention and appraisal costs decrease and the rate of growth in failure costs are unaffected. Rapid speed of quality improvement does yield lesser decreases in failure costs than slower, steadier improvement. However, rapid speed of quality improvement does not yield the predicted lesser decrease in prevention and appraisal costs than slower, steadier improvement. Rapid speed of quality improvement might or might not benefit the organization, perhaps an explanation for some Total Quality Management (TQM) failures. A more deliberate, learning organization is suggested from this research.     

OPTIMAL AND NEAR OPTIMAL CONTROL OF A TWO-PART-TYPE STOCHASTIC MANUFACTURING SYSTEM WITH DYNAMIC SETUPS

This paper deals with a manufacturing system consisting of a single machine subject to random failures and repairs. The machine can produce two types of parts. When the production is switched from one part type to the other, a random setup time is incurred at a constant cost rate. The objective is to track the demand, while keeping the work-in-process as close as possible to zero for both products. The problem is formulated as an optimal stochastic control problem. The optimal policy is obtained numerically by discretizing the continuous time continuous state opti-mality conditions using a Markov chain approximation technique. The discretized optimality conditions are shown to correspond to an infinite horizon, discrete time, discrete state dynamic programming problem. The optimal setup policy is shown to have two different structures depending on the parameters of the system. A heuristic policy is proposed to approximate the optimal setup policy. Simulation results show that the heuristic policy is a very good approximation for sufficiently reliable systems.