基于复杂供应链库存管理策略的系统动力学研究

在分析了具有不同提前期和加工时间的复杂供应链特点基础上，研究了混合CONWIP／Kanban库存管理思想与同步CONWIP库存管理思想在复杂供应链上的应用。同时借助Vensim建模平台。针对这两种管理思想建立了基于复杂供应链系统的动态仿真模型，并对模拟结果进行了分析。     

大型联合企业备件库存控制策略研究

建立了零备件库存两级多点存储模式的最佳备件库存模型,给出了总库存成本（库存成本与转运成本之和）最小时的各库存点与仓库的最优订货策略的求解算法,提出了以服务水平为约束,以库存成本和转运成本最小为目标的规划模型．给出了已知订货批量,求最优订货点的算法,并通过实际应用验证了该算法的有效性。     

动力煤供应链多级库存控制模型与算法研究

为了降低动力煤供应链库存总成本,并保障动力煤资源供需系统持续稳定运行,引入多级库存控制理论,建立了基于成本最小化的动力煤供应链多级库存控制概念模型与数学模型,设计了遗传算法求解储配煤基地和区域性配送中心的最佳订货点、订货批量及调拨批量。最后,通过算例证明了该模型与算法的有效性和实用性。基于上述研究结论,为我国动力煤供应链库存控制提供了决策支持和对策建议。     

批量处置下逆向物流运作中销售商库存优化控制数学模型的构建

以销售商对逆向物流退回产品进行批量处置为基础,研究了其库存优化控制问题,将该问题转化为销售商总订货成本最小化时的最优订货周期和最优订货数量求解问题,基于相关假设和参数设定,构建了库存优化控制模型并对该模型进行了算例检验。研究结果表明,随着客户退货强度的增加,销售商的最优订货周期将会相应地延长,而订货成本会相应地降低,在供应链逆向物流实际运作中,销售商可以以批量处置规模效益为目标,根据实际情况对模型的参数进行灵活的掌握,从而有效地实现库存的优化控制。     

考虑处置和延迟交货影响的制造与再制造批量决策

对一个制造与再制造业务并存的生产系统进行研究。在此系统中,旧产品从顾客返回,因再制造能力的不足,仅有部分用于再制造,其余的被处置。恒定的需求由服务性产品来满足,允许缺货但需完全拖后补足。服务性产品库存由制造新品与再制造品组成,可翻新品库存由用于再制造的旧产品组成。在(1,R)策略下构建了库存决策模型,给出了确定最优制造与再制造批量等决策变量的求解方法,得到了相应的求解公式。     

生鲜食品的二级补货系统优化研究

针对连锁超市的配送网络。建立一个两级的库存系统模型，其中包括一个中心仓库和若干门店，每个门店面对的是随机的相互独立的需求，该需求服从正态分布。该库存系统是采用基于连续检测的再订货点方法管理。本文针对超市的生鲜食品补货的特征，增加对于过剩成本的考虑，采用分散库存控制权的方法，按照从门店到配送中心的思路。优化总库存成本，从而得出最佳的订购批量，同时也得出最佳的产品供给水平、再订货点等。     

考虑处置和延迟交货影响的制造与再制造批量决策

对一个制造与再制造业务并存的生产系统进行研究.在此系统中,旧产品从顾客返回,因再制造能力的不足,仅有部分用于再制造,其余的被处置.恒定的需求由服务性产品来满足,允许缺货但需完全拖后补足.服务性产品库存由制造新品与再制造品组成,可翻新品库存由用于再制造的旧产品组成.在(1,R)策略下构建了库存决策模型,给出了确定最优制造与再制造批量等决策变量的求解方法,得到了相应的求解公式.     

基于定期检查处理的逆向物流库存控制研究

针对再制造逆向物流系统,研究整个供应链的逆向物流库存控制问题,考虑多种产品和原材料,建立一种具有周期相关的再制造逆向物流多级库存控制模型,该模型可以确定新产品的制造批量和回收产品的再制造批量,达到优化供应链库存、减少库存总成本的目的。     

考虑多种产品的随机库存系统仿真及优化研究

结合现实库存状况,利用可视化通用交互集成仿真软件Arena建立包含多个产品的库存控制系统模型,得到给定(s,S)的平均库存成本。最后利用模型参数优化器Optquest辅助求解最优结果及对应的(s,S),达到平均库存成本的最小化。另外,客户对于缺货状况的不同态度直接影响到缺货成本的计算,因此建模时也将此因素考虑在内。     

供需交互情境下提前期可控的Stackelberg博弈研究

文章针对制造商为领导方、零售商为从方的两级供应链,将传统模型中的生产准备时间、提前期等已知参数推广为决策变量。在供应链提前期是由制造商与零售商的决策共同控制的条件下,建立了制造商先确定生产率和生产准备时间,零售商随后确定订货批量和安全库存因子的stackelberg博弈模型,并基于二层规划的思想设计了有效的迭代算法,给出了数值算例。分析的结果表明：与传统模型相比,通过对可控变量的优化,可以有效地降低提前期,从而减少了供需双方和供应链整体的总成本。     

A generalized lot sizing model for the process cycling problem

Most scheduling/lot sizing models for the single-machine problem assume that aggregate demand equals aggregate production; and that backorders are to be avoided. Where working inventories are low, the scheduler may wish to avoid short production runs and willingly incur some backorder penalties so as to increase the length of production runs and reduce setup costs per unit of time. The model proposed here identifies optimal lot sizes with respect to the backorder/setup cost relationships. Use of the model will result in an optimally balanced inventory even when aggregate inventory levels are changing.     

基于JIT思想对汽车玻璃生产线WIP的控制策略

本文分析了汽车玻璃加工生产线的生产流程,生产车间不同种类的在制品(WIP)数量很庞大,为此研究生产线的瓶颈工序,得到瓶颈工序生产线的切换时间对WIP库存的影响,研究生产线的切换时间、工序之间的生产节拍比和WIP库存数三者之间的关系,结合JIT和WIP库存控制策略来保证生产线的流畅生产,归纳出关键的工序节拍比下所需的WIP库存数的动态变化情况,从而动态地控制WIP库存的变化并最大程度地降低车间的WIP库存。     

基于提前期的CONWIP/Pull供应链库存模式研究

在分析目前汽车行业供应链库存管理存在问题的基础上,结合生产控制系统的CONWIP生产控制模式的特点提出了汽车行业的基于提前期的CONWIP/Pull供应链库存管理模式,并建立了相关的数学模型。     

The effect of lot-sizing on workload variability

Lot-sizing models which group demand requirements for one or more consecutive time periods into a single production run have received considerable attention in recent years. Material Requirements Planning (MRP) systems must, for instance, make a lot-size decision for each planned order release. Existing decision models attempt to minimize the sum of setup plus inventory holding costs. However, lot-sizing tends to increase the work center load variability, and, consequently, the costs associated with changing production levels from period to period should be incorporated into the economic analysis. This study is concerned, first of all, with analytically describing the relationship between dynamic lot-sizing models and workload variability. Secondly, in order to account for production level change costs we propose a simple modification to existing heuristic models. Lastly, we employ a simulation model to empirically extend these results to a typical MRP multiechelon production environment. An example is included to show clearly that with cost premiums for overtime and severance or guaranteed minimum costs for undertime the traditional lot-sizing techniques significantly underestimate actual costs and can lead to very costly policies.Mean, variance and coefficient of variation of period work time requirements are derived as a function of several algorithm characteristics. Average cycle time (number of periods covered by a single batch) is found to be the most influential factor in determining workload variability. Variance grows approximately in proportion to this cycle time with the proportionality constant being the square of average period workload. Cycle time and demand variability also contribute to workload variability. Results indicate that for a given average cycle time, the EOQ method will minimize workload variability. When N products utilize the same work center, the coefficient of load variation will be reduced by a factor of N^{?$\text{1}\text{2}$} unless requirements are positively correlated. Positive correlation would result when products have similar seasons or parent items. In this case grouping such products cannot help reduce variability.In order to incorporate production level change costs into existing heuristics we may simply introduce a term consisting of a penalty factor times average cycle time. The penalty factor represents the costs of period by period production level changes. Several popular heuristics are extended in this fashion, and it is found that solutions are still readily obtainable, requiring only modifications to setup or holding cost parameters.The effects of level change costs are examined via simulation for a specific yet typical environment. It is found that when setup costs are significant, traditional lot-sizing heuristics can provide cost savings and service level improvements as compared to lot-for-lot production. However, whereas for our model the obtainable profit improvement from lot-sizing was 25% in the case of freely variable capacity, actual improvements were only one half as large when reasonable hiring and firing practices and overtime and undertime costs were considered. Consequently, management needs to consider carefully labor costs and work center product relationships when determining a production scheduling method.     

生产物流平衡的持续优化在硬盘磁头制造业的应用

以广东某硬盘磁头代工企业生产线为研究对象，运用装配线平整技术，以生产物流平衡为目标分析了设备能力、任务分配、工装改善以及生产计划排配等方面存在的问题：提出并实施了改善方棠。保证了生产线的物流负荷平衡。优化方案的实施使企业生产能力提高并有效地降低了生产线在制堆积的问题，在制品周转从3．2天缩短到2．5天，生产现场的环境也得到了改善。     

A lot sizing and sequencing algorithm for dynamic demands upon a single facility

A heuristic algorithm is developed and applied to determine lot sizes and production sequence on a single facility. The various product demands are treated as deterministic and time varying (dynamic) over a finite planning horizon, such as that generated from a material requirements planning (MRP) system.In contrast to other approaches available, the algorithm considers the sequencing decision in each period by realistically assuming inventory holding cost occurrence in the period of production, and in addition, it is capable of considering set-up times where such set-up times consume available productive capacity. The ability to handle numerous products, and the capability of being able to specify maintenance time and holidays is an integral aspect of the algorithm.The results of an application of the algorithm in a medium size bearing company have shown very significant reduction in the controllable inventory holding cost while eliminating late deliveries. In an effort to cope with potential realistic schedule alterations, different solutions were developed for managerial evaluation providing greater flexibility but at a higher cost.     

电子产品的回收物流库存控制研究

研究了价值随时间迅速衰减的电子类产品的回收物流库存控制系统。回收物流系统中既包含一般制造的新产品,也包含回收再制造的产品,而且该类产品的更新换代很快,产品生命周期很短。运用最优库存理论,推导出了在不同控制方式下的EOQ模型,以确定最优生产批量和最优再造批量。     

随机需求下销售周期对零售商绩效影响的仿真分析

运用系统动力学方法构建了包含市场需求、企业生产、劳动力和库存管理的一级供应链运作模型。通过灵敏度和优化分析仿真技术研究了随机需求下产品销售周期对零售商成本、利润和供应链牛鞭效应的影响。结论显示,与生产成本和劳动力成本相比,库存成本对产品销售周期的变化更敏感;在不考虑生产启动成本情况下,随着销售周期增大,总利润呈线性递减;连续库存补充计划比传统的经济订货批量模式能够为企业带来更多的利润,更有利于减弱牛鞭效应的影响。     

逆向物流确定型库存控制策略研究

研究了逆向物流中的需求确定的库存控制策略,并给出了在几种不同处理方式下的EOQ模型。由此确定了最优的订购批量和修复批量,并对求得的批量进行修正,使得循环周期中的订货次数为整数。该模型的形式、结构简单,易于在实践中应用。     

A comparison of MRP lot sizing methods considering capacity change costs

Capacity management is the planning and leveling of resources required (load) against the resources available (capacity). In this study, the lot size models used by Material Requirements Planning (MRP) had a major effect on the work center load profiles generated by Capacity Requirements Planning (CRP). Therefore, the selection of lot size models for MRP systems is an important decision for capacity management as well as materials management.The results of this study highlight the operating characteristics of specific lot size models considering setup, inventory carrying, and capacity associated costs. For example, the Economic Order Quantity model and the Lot-For-Lot model in certain situations can help level load. The Periodic Order Quantity and Least Total Cost models especially for high cost structure ratios tend to result in erratic and lumpy work center load profiles. The reasons for such operating behavior are examined. Other concepts and relationships important to capacity management are discussed.