Earliness/Tardiness Production Scheduling and Planning,and solutions

Earliness/Tardiness Production Planning (ETPSP) has attracted much attention in recent years. In practice, it provides an efficient way to integrate Manufacturing Resource Planning (MRP-II) Scheduling and with Just-In Time (JIT). Conventional research mainly focused on the condition of single-machine and parallel multi-machine. Capacity balance has not been considered. Some investigations of existing research on ETPSP are given in this paper. An extensive model of ETPSP with consideration of multi-process capacity balance for manufacturing systems is proposed. Two alternative solutions, key-process method and relaxation method, are both developed to solve ETPSP. Computational results identify that both methods are powerful to solve ETPSP which minimizes total earliness and tardiness penalties. Furthermore, some comparisons between these two methods and other conventional methods indicate the efficiency of the former.     

The sensitivity of job mix and load capacity bottlenecks on inventory and due date performance in a manufacturing system

Based on a benchmark job-lot manufacturing system a simulation study was carried out to compare the performance of just-in-time (JIT) shop control system Kanban with conventional job-shop control procedures. The shop control policies were tested under a good manufacturing environment and the effects of job mix and load capacity bottlenecks on various shop control policies were tested. From the simulation results, it is inferred that there are shop control procedures that perform better than the Kanban in a job shop. It has been observed that even with adequate capacity, bottleneck areas surface due to fluctuations in the shop load. Kanban is not appropriate in such a situation because capacity bottlenecks can significantly reduce the ell'ectiveness of a pull system. The disparateness in the processing requirements for jobs can seriously undermine the performance of the shop. This is the type of shop environment where the shop control procedures will be most effective. Although Kanban came out best when the load capacity bottlenecks and the disparateness of the job mix were removed, the selected shop control variable combinations closely approximated the Kanban result. Although many features of JIT can be implemented in any system, companies trying to adopt JIT should remember that Kanban requires a rigid system intolerant of any deviation.     

A heterarchical generic discrete manufacturing simulation model and its application in a world class manufacturing environment

Current factory design and evaluation is very primitive. Factory components are designed in many cases independently. Product and process design are not well integrated. An encompassing framework is needed for iterating through a series of total factory designs, searching for optimal performance. In addition, a vehicle is needed for predicting the performance of a proposed advanced manufacturing system, so that engineers may have a sound means for evaluating such proposals. A heterarchical discrete manufacturing SIMNET II simulation model (SIMCELLS) was developed as a comprehensive methodology for designing and evaluating discrete manufacturing systems. SIMCELLS allows manufacturing systems engineers to experiment with alternative system structures and control strategies while seeking that combination of design features that will produce the desired overall system performance. The model in combination with a modernization programme is enabling a firm to successfully manufacture and sell trucks meeting international standards. The SIMNET II model     

A structured methodology to implement judiciously the right JIT tactics

In order to enhance the competitiveness and efficiency of manufacturing operations, many companies arc looking at implementing key strategic technologies. Two of the most predominant programs are ‘just-in-time’ and ‘synchronous organizations’. However, their impacts on improving quality and reducing time-to-market have been mixed. It is not very clear why, in some cases, results are poor, when in a similar situation, programmes have proved to work well. There are conflicting reasons reported for such a discrepancy. Some have argued that during J IT implementation either a right mix of tactics was not selected at the outset or the process was not carefully monitored to see whether a mid-course correction or change in tactics was necessary. In order to (a) protect the manufacturing and strategic teams from making the same/similar mistakes and (b) sustain a series of successful activity throughout during the strategic implementation cycle, this paper outlines a structured methodology. The method utilizes a matrix-based procedure to dynamically (over time) measure the effectiveness of a line of JIT tactics against the organization's principles and objectives. The operating procedure suggests first (a) using a method for monitoring the changing conditions of market and business and then (b) using the metrics to guide the management with a new line of tactics that might have better impact on the newly aligned company goals. In an effort to help managers and engineers decide on a proper line of tactics to implement JIT, a line of JIT quality matrices (JQM) is developed. JQM provides a framework to guide group managers to ‘plan, pick and choose’ a set of effective JIT techniques. An approach similar to quality function deployment (QFD) is used to generate the JIT house and their corresponding JQM matrices. With the JQM-based structured methodology, managers can design the best line of JIT strategy blended with JIT theory and adapted to the manufacturing environments in which it is expected to operate.     

Inventory Control when the Lead‐time Changes

A single‐echelon inventory system with continuous review and Poisson demand is considered. There are standard linear holding and backorder costs but no ordering or set‐up costs. We study a change in the lead‐time, which is rather typical in connection with application of a Just‐In‐Time philosophy. Our main focus is a lead‐time decrease but we also consider a lead‐time increase. Due to the lead‐time change, the optimal steady state solution will also, in general, change. We consider the transient problem of minimizing the costs when bringing the system from its original steady state to the new steady state.     

基于Supply-hub的2个供应商单制造商批量协调问题研究

考虑一个由2个供应商和单制造商组成的装配型供应链,分析并建立了制造商、Supply-hub和2个供应商的平均成本函数,提出了分别由制造商和2个供应商负责Supply-hub营运及成本时的生产与订货批量模型。研究结果表明:当由制造商负责时,供应商距离Supply-hub越远,制造商的生产批量越大,且Supply-hub中的零部件补货批量相比供应商负责时更大;当由供应商负责时,制造商的生产批量不随供应商的远近而变化,供应商的零部件生产批量也不变。此外,在适用Supply-hub的条件下,相比由制造商负责,由2个供应商负责Supply-hub的运营并分担其成本时,整个供应链的总成本更低,2个供应商与制造商之间可以通过合理分配使2个供应商与制造商的营运成本均有所降低,从而实现整个供应链系统的Pareto优化。     

考虑顾客缺货反应的多产品两阶段JIT联合订货

为了解决多产品两阶段联合订货决策问题,综合考虑顾客缺货反应及资源限制对订货决策的影响,提出资源限制条件下考虑CRS的多产品两阶段JIT联合订货策略。在此基础上,以零售商收益最大化为目标,建立了多产品两阶段JIT联合订货决策模型,并从初始解生成和殖民地国家革命方式两方面设计了改进的帝国主义竞争算法。从Gruen调查报告中选取三种不同规模的算例验证了模型和算法的适用性和有效性。研究表明：本文提出的考虑顾客缺货反应的多产品两阶段JIT联合订货方法既可以提高零售商的总收益,也能提高顾客的服务水平;当单位库存资源机会收益相近时,同组产品间不会发生替代情况,而当同组产品间的单位库存资源机会收益差距较大,且高于其他产品组的单位库存资源机会收益时,则该产品组便会出现缺货和替代情况,且若该组缺货产品的剩余资源单位机会收益小于其他组产品的单位资源机会收益,则该产品的剩余资源便会转移给其他缺货产品。研究结论可为零售商多产品两阶段JIT联合订货决策提供有益的参考。     

MRPII与JIT集成及其信息化研究

本文先讨论MRPII与JIT各自的原理和它们之间的比较,在这基础上再结合Jade ERP系统探讨MRPII与JIT的集成与信息化,将MRPII作为企业的计划系统,而用JIT作为计划的执行系统.提出了结合MRPII规划功能与JIT执行功能的混合式生产与配送系统,以及探讨了在两者集成中实施的问题.     

准时生产方式下混流装配线的调度问题

混流装配线的调度问题是 JIT生产方式中的一个重要问题 .本文建立了多级混流装配线的调度模型 ,其目标是使不同生产级上各零部件的消耗量尽可能保持均匀 ,并用遗传算法和模拟退火进行求解 .试验表明 :遗传算法和模拟退火算法的求解质量比“目标追随法”有所提高     

The impact of critical success factors of JIT implementation on organizational performance

Much has been written and publicized about the virtues of JIT philosophies during the past decade. However, relatively limited empirical research has been reported con-cerningJIT implementation on organizational performance. This study presents the results of an empirical study which utilized both concrete financial accounting data and a broad cross-sectional survey as measures of organizational performance to determine the impact of each JIT implementation requirement factor to organizational performance. Communication between production and marketing departments was identified as a critical factor for increased inventory turnover and work-in-process inventory turnover, while employees' participation and the bottom-up management approach were determined as significant factors for improving quality and flexibility. The results of this study imply that in JTT environment personnel management practices, such as bottom-up management encouraging employees participation, and organization management such as a communications linking the production and marketing departments, are more important than JIT practices themselves.