基于多级库存的电网运维物资安全库存优化配置研究

针对电力公司运维物资多级库存体系与安全库存配置现状,结合安全库存聚集效应,文章提出了周转库安全库存差异聚集策略。在综合考虑库存持有成本与普通、紧急配送成本的基础上,构建了安全库存优化配置模型。通过两类电网运维物资实际数据的分析,验证了差异聚集策略下成本低于全部聚集以及全部分散策略,可以为电力公司物资集约化、差异化、精益化管理以及仓库定额配置提供依据。     

A multi-echelon supply chain model for reworkable items in multiple-markets with supply disruption

The objective of this paper is to develop a multi-echelon supply chain model for multiple-markets with different selling seasons. Here, two suppliers are involved to supply the raw materials to the manufacturer where the main supplier may face supply disruption after a random time and the secondary supplier is perfectly reliable but more expensive than the main supplier. In this article, the manufacturer produces a random proportion of defective items which are reworked after regular production and are sold in a lot to another market just after completion of rework. The retailer sells the finished products in different markets according to seasons. Finally, an integrated expected cost per unit product of the chain is minimized analytically by considering the lot-size ordered as a decision variable. An appropriate numerical example is also provided to justify the proposed model.     

A two-echelon inventory allocation and distribution center location analysis

The optimization of locations for distribution centers is influenced by the demand for individual products. Lower demand products are often more effectively held in more centralized locations than higher demand products. This paper presents a model for optimizing the location of inventory for individual products in a multi-product two-echelon inventory system and the integration of those decisions into the location analysis for distribution centers. A realistic application of the analysis process is discussed.     

Near-optimal (r,Q) policies for a two-stage serial inventory system with Poisson demand

We consider a two-stage serial inventory system whose cost structure exhibits economies of scale in both stages. In the system, stage 1 faces Poisson demand and replenishes its inventory from stage 2, and the latter stage in turn orders from an outside supplier with unlimited stock. Each shipment, either to stage 2 or to stage 1, incurs a fixed setup cost. We derive important properties for a given echelon-stock (r, Q) policy for an approximation of the problem where all states are continuous. Based on these properties, we design a simple heuristic algorithm that can be used to find a near-optimal (r, Q) policy for the original problem. Numerical examples are given to demonstrate the effectiveness of the algorithm.     

基于商品性质的多级分销模式选择及网络库存定位模型的研究

本文以典型的多级分销网络为研究对象,从商品的需求量、需求波动及商品价值等特性对分销网络的服务能力和成本水平的影响出发,对如何根据不同商品特性选择科学的分销模式及如何在多级网络中进行合理的库存定位问题进行了研究,并基于此提出了一个可行的定性分析模型,借助此模型,可帮助企业在设计分销网络和现有网络的优化过程中,根据所经营商品的不同特性进行合理的网络设计和运营,大大提高网络运营效率。     

Strategic safety stock placement in supply chain design with due-date based demand

We present a strategic safety stock placement model in supply chain design for assembly-type product with due-date based demand, where demand data are based on dates when company has to ship to customers rather than order receiving dates. We formulate multi-echelon stock placement by guaranteed-service model with demand propagation equations through backward explosion, where demand can be either stationary or nonstationary. The stock placement model is incorporated into network design problem and its optimization procedure is provided. We show effectiveness of the optimization procedure and other significant features of the model through numerical examples of a machinery product supply chain.     

基于Extendsim的多级库存系统仿真

针对多级库存难以控制的问题,利用Extendsim软件对需求和提前期均随机的多级库存系统进行建模和仿真,以供应链的利润最大化为目标,结合该软件的Optimizer模块,对多级库存各节点的订货点、订货量进行遗传算法计算。从而有效地解决了多级库存难以管理的问题。     

Investigating the value of information sharing in multi-echelon supply chains

Under the structure of multiple business entities, supply chain management (SCM) offers the external and internal integration of business processes in enterprises. The most important objective of SCM is to enhance the supply chain performance such as reinforcing the service level and increasing profit as well as reducing order cycle time and inventory. In recent years, due to the advancement of information technology, enterprises can manage the product flow and the information flow via economical and efficient mechanisms. The well-organized information sharing can enhance the supply chain performance and allow enterprises to refine their strategies of supply chain in order to maximize their profits. The previous studies pointed out the positive effect of information sharing on the efficiency of supply chain. However, relatively little literature focuses on the performance analysis for multi-echelon supply chain with various information sharing scenarios. By using the simulation technique, this paper models different scenarios of information sharing, and further analyzes the impacts of information quality on multi-echelon supply chain performance. In addition, this paper employs Data Envelopment Analysis (DEA) to integrate multiple performance measures to ensure the information sharing scenarios with enhanced performance.     

Common inventory modeling assumptions that fall short: Arborescent networks, Poisson demand, and single-echelon approximations

Traditional multi-echelon inventory theory focuses on arborescent supply chains that use a central warehouse which replenishes remote warehouses. The remote warehouses serve customers in their respective regions. Common assumptions in the academic literature include use of the Poisson demand process and instantaneous unit-by-unit replenishment. In the practitioner literature, single-echelon approximations are advised for setting safety stock to deal with lead time, demand, and supply variations in these settings. Using data from a U.S. supplier of home improvement products, we find that neither the assumptions from the academic literature nor the approximations from the practitioner literature necessarily work well in practice.In a variation of the strictly arborescent supply chain, the central warehouse at our real company not only replenishes other warehouses but also meets demand from customers in the region near the central warehouse. In this paper, we study this dual-role central warehouse structure, which we believe is common in practice. Using high and low volume product demand data from this company, we use Monte Carlo simulations to study the impact of (1) the use of a dual-role centralized warehouse, (2) common demand assumptions made in multi-echelon research, and (3) single-echelon approximations for managing a multi-echelon supply chain. We explore each of these under both centralized and decentralized control logic. We find that the common assumptions of theoretical models impede their usefulness and that heuristics that ignore the actual supply chain structure fail to account for additional opportunities to utilize safety stock more effectively. Researchers should be aware of the gap between standard assumptions in traditional literature and actual practice, and critically evaluate their assumptions to find a reasonable balance between tractability and relevance.     

需求确定型多级库存优化模型研究

多级库存管理对于企业来说具有重要的意义,在需求确定的情形下对库存模型进行了分析,建立了基于确定需求的多级库存数学模型,包括一个单目标模型和一个多目标模型,使供应链的效率得到了有效提高。