Modeling and solving a one-supplier multi-vehicle production-inventory-distribution problem with clustered retailers

This paper considers a supply chain management problem which integrates production, inventory, and distribution decisions. The supply chain is composed of one supplier production facility and several retailers located in a given geographic region. The supplier is responsible for the production and the replenishment of the inventory of retailers, in a vendor managed inventory (VMI) context. The distance between retailers is negligible compared to the distance between the supplier and the retailers’ region. Thus, for each vehicle, there is a major fixed cost for traveling to the cluster of retailers and a minor fixed cost for visiting each individual retailer. The problem consists of determining quantities to be produced, quantities to be delivered to retailers, vehicles to be used, and retailers to be serviced by each vehicle. This problem is an extension of the one warehouse multi-retailer problem with the consideration of production planning and storage and vehicle capacity limitations in addition to fixed vehicle utilization costs and retailer servicing costs. The objective is to minimize a total cost composed of production, transportation, and inventory holding costs at the supplier and at the retailers. Two mixed integer linear programming formulations are proposed and six families of valid inequalities are added to strengthen these formulations. Two of these families are new and the others are adapted from the literature. The numerical results show that the valid inequalities considerably improve the quality of the formulations. Moreover, the parameters that influence the most computational times are analyzed.     

弹性需求下带有分摊运费的供应链协调策略

研究了弹性需求条件下,由单一零售商和单一供应商组成的两级供应链的协调订货问题.该协调运用了共同补给期和分担运输费用的双重策略,分别从订货周期及年需求量的角度协调供应链订货.在Stackelberg博弈的框架下,首先从实际出发,引入了零售商最优转让折扣率,再从供应商的角度建立了协调模型,然后讨论了求解算法,并利用数值试验方法,通过仿真研究说明了该协调策略的有效性和可行性.     

Synchronization in multi-echelon supply chain applying timing discount

Due to the increasing emphasis on the effective management of the supply chain, synchronization and cooperation issues between suppliers and retailers in decentralized multi-echelon inventory/distribution systems have gained much attention in the recent years. In this paper, we consider coordination issues of a distribution system composed of a manufacturer, a supplier (distributor), and several retailers. The supplier outsourcing a third party offers a timing discount to multiple retailers in order to synchronize the timing of their orders with the order cycle. It is also assumed that retailers are allowed to face stock outs. In this paper, a mathematical model is developed to analyze the problem. Results show that while synchronizing the supplier and the outsourcer enhances the supply chain efficiency, offering any type of timing discount by the supplier decreases the supply chain efficiency. It is also noted that having coordination between the manufacturer and the supplier has no impact on the supplier’s profit but may decrease the retailer’s costs. It is believed that our findings provide potential and significant managerial implications in the area of supply chain coordination when these systems are decentralized.     

大规模定制环境下供应链实施延迟生产的成本优化模型

为成功实施延迟生产以实现供应链成本的优化,大规模定制环境下供应链各节点企业需要紧密协作.针对一条包括制造商和供应商两个节点企业的供应链.建立了大规模定制环境下供应链实施延迟生产的成本优化模型.以最小化供应链生产成本为目标,研究了供应商对客户订单分离点决策的影响,以及大规模定制环境下供应链实施延迟生产时客户订单分离点的最佳位置,指出决策客户订单分离点时应考虑供应商成本.最后,对该生产成本优化模型进行了仿真.     

一对多供应链在传统、信息共享和供应商管理库存模式下的绩效比较

比较分析了一对多两阶段供应链在传统、信息共享和供应商管理库存三种供应链管理模式下的供应链绩效,其中绩效指标选取为平均成本.针对三种模式分别构建了供应商、零售商以及供应链整体的运作模型,给出了其成本的解析表达式,最后通过数值实验的方法,比较了三种模式下的供应链绩效.结果表明,对于零售商和整个供应链而言,信息共享模式优于传统模式,并且供应商管理库存模式优于信息共享模式;而对于供应商而言,信息共享和供应商管理库存模式均优于传统模式,但供应商管理库存模式与信息共享模式相比,在一定条件下,有可能带来供应商成本的增加.     

季节性商品两级供应链契约设计与协调模型研究综述

在季节性商品销售环境下,讨论了单节点成员两级供应链契约设计与协调模型研究状况。在此基础上,讨论了多供应商对单零售商、单供应商对多零售商、多供应商对多零售商等不同供应链结构下的契约设计与协调模型研究现状。综述了复杂决策环境对契约设计与供应链协调的影响。总结了目前的研究现状,并提出了今后的研究方向。     

Developing a two-echelon mathematical model for a vendor-managed inventory (VMI) system

Vendor-managed inventory (VMI) system is a mechanism where the supplier creates the purchase orders based on the demand information exchanged by the retailer/customer. In this paper, the performance of the traditional and VMI system is compared. Mathematical modeling is applied and total inventory cost in the supply chain is used as the performance measure. The supply chain is considered in two levels, i.e., buyer and supplier, with the assumption that the supplier faces only one buyer as the contract party. Since none of the previous works quantitatively directed the practitioners to select the traditional or VMI system, the extent point is introduced in which the difference in total cost of both systems is minimal. It is applied to investigate how increasing or reducing the related parameters changes total cost of two systems with respect to each other. A numerical example and sensitivity analysis are provided to illustrate the theory and derive the extent points and percentage of difference in total cost of the traditional and VMI system. The results show that VMI works better and delivers lower cost in all conditions including back order, and as one goes farther from the extent point, the application of VMI is more justified.     

基于共同补给期的直运型供应链库存协调模型及仿真

研究了二级直运供应链通过共同补给期协调库存的策略问题。在该供应链中,单一的供应商向面临随机需求的多个零售商提供单一产品。在提出的库存协调策略下,当零售商接受供应商提供的共同补给期时,供应商则提供给零售商一定的价格折扣。最后,通过数值仿真分析,验证了该策略可以降低供应商的成本,而零售商成本的增加则可以通过价格折扣来补偿,从而显著地降低了供应链的总成本。     

供应链协同契约研究

为了使供应链达到协同,提出了利润共享与买回契约组合而成的新型混合契约,并用该契约对单供应商一单零售商,以及单供应商一多零售商组成的两级供应链模型进行了协同分析,整个分析过程采用了Stackel-berg博弈理论,其中供应商作为领导者,零售商作为跟随者.分析结果和数值实例说明,混合契约可以使供应商与零售商协同,并使供应链渠道总利润最大化.     

Two-echelon supply chain coordination among manufacturer and duopolies retailers with recycling facility

To reduce pollution and more uses of natural resources, the concept of recycle of used products and apply to everyday life is urgent for maintaining a sustainable life. In this context, an important positive strategy is to buy products when one customer does have to throw an item away. Based on this concept, the demand function of end customers is assumed as sales prices and recycling factors sensitive. In this paper, we develop cooperative as well as non-cooperative model of a closed-loop supply chain that consists of a manufacturer and duopolies retailers and compare the model with cournot and collusion games. Under Stackelberg setting among the manufacturer and the retailers, the duopolies retailers compete with each other under cournot and collusion games. A numerical example is given to justify the proposed model.     

供应商管理库存环境下库存与发货策略研究

供应商管理库存是最先进的供应链库存管理模式,也是供应链发展的重要方向.在含有多零售商的供应商管理库存环境下,为了同时满足最小化企业运营成本和最大化顾客服务水平这两个目标,分析了原有发货策略的不足,提出了新的基于时间和数量的混合发货策略,通过理论分析和仿真实验表明,混合发货策略能较好地均衡企业运营成本和顾客服务水平,更好地支撑了企业决策.     

A cost model for determining dyeing postponement in garment supply chain

There is a complex, dynamic and highly competitive market for the textile and clothing industries in developed countries. To respond quickly to changes in the market and to insure that the response will be able to satisfy customer fashion requirements, postponement strategy is one of the most important methods. This paper constructs original and postponed garment dyeing cost models and uses practical parameter data to simulate various situations, and then analyzes the differences and relations between the two cost models. The results show that the cost of the postponement model is lower than the cost of the original model when key parameters such as total demand quantity, number of colors, inventory holding cost rate, demand standard deviation, lead-time, and safety stock factor are large. The cost evaluation model provides a strategy and the basis for feasible judgment in evaluating dyeing postponement for the textile and clothing industries in garment supply chain management.     

Enlightening supplies [supply chain information]

Speed of information flow through a supply chain directly affects its operating success. There are 2 “pipelines”, one conveying orders from the customer towards the raw materials supplier and one conveying product the other way. The authors present the case for retail sales information to be shared freely with all tiers of the supply chain     

基于超模博弈的多零售商价格竞争的均衡分析

研究了单个供应商和多个零售商组成的供应链环境下,多零售商间价格竞争的均衡行为.供应商与零售商通过收益共享契约进行交易,需求随机且价格敏感,零售商间进行价格竞争.引入了超模博弈理论,证明了零售商间的价格竞争一定存在纯策略纳什均衡,分析了均衡结果的一些特点,给出了存在唯一均衡价格的条件,并通过比较静态分析,得出了零售商定价随契约参数变化的规律.最后,通过一个算例对相关命题进行了验证.     

An integration of assembly planning by design into supply chain planning

A supply chain needs to consider the quality of a product as well as the quality of manufacturing process to satisfy customer requirements at efficient resources planning in terms of safety stock allocation and vendor–buyer coordination. The objective of this article is to use an axiomatic approach to make assembly planning by designing and integrating assembly into supply chain planning, particularly during supply chain reconfiguration. The effect of fixture layout planning, the accuracy of demand forecast, and the supplier capability of providing the required material quality are studied. An optimum supply chain network is configured by combining the product, assembly, and supply chain planning. Heuristic-based optimization is used to validate the proposed solution. The performance of the system is measured in terms of lead time variability, the number of backorders, and the level of safety stock. The results and analysis indicate that the axiomatic approach is capable of reducing the assembly variation and employing necessary fixture layout planning to deliver product intents. In addition, the reduction of assembly variation also reduces the safety stock, lead time variability, and backorders. Finally, management decision making is discussed among other concluding remarks.     

A two-level distribution inventory system with stochastic lead time at the lower echelon

We consider a two-level distribution inventory system with a number of identical retailers at the lower echelon and a single supplier at the upper echelon. The replenishment policy is continuous review policy (R, Q) at all installations. We assume independent Poisson demands with stochastic lead time for the retailers and a constant transportation time for replenishing supplier orders from an external warehouse. Unsatisfied demands are assumed to be lost in the retailers and unsatisfied retailer orders are backordered in the supplier. We develop an approximate cost function to find optimal reorder points for given batch sizes in all installations, and the related accuracy is assessed through simulation. We present numerical examples for the gamma distributed lead time for the retailers orders at the supplier.     

Mitigating the bullwhip effect by reducing demand variance in the supply chain

To coordinate an agile manufacturing system with the high-level requirements of marketing services, supply chain management (SCM) plays an important role in management activities for enterprise globalization. In SCM, a phenomenon called the “bullwhip effect” has attracted considerable attention. Beyond the previous studies, we consider multiple retailers with one supplier in the supply chain and examine ways in which the supplier can reduce the total demand variance by adjusting retailers’ order sizes. The results reveal that the total demand variance can be reduced by using portfolio theory to adjust the order sizes based on the variance of order of the retailer. Therefore, the bullwhip effect can be partially reduced by our proposed method .     

敏捷供应体系中虚拟企业增广供应特征模型的建造

在供应体系中建立虚拟企业是实现企业敏捷制造的一个有效途径。提出面向供应体系的增广供应特征模型,建立基于零部件级／工序级的零部件增广供应特征模型、供应商与制造企业增广供应特征模型及其各自的编码体系,为实现对供应商的虚拟企业动态合作性评估奠定了理论基础。     

A multi-objective supply chain model integrated with location of distribution centers and supplier selection decisions

Today, in the competitive markets, supply chain works as an interrelating network of suppliers, manufacturers, distributors, and customers, to satisfy customer demands. Coordinating all parts of the supply chain is a multi-level process and needs important decisions that affect on the performance of each part and whole supply chain and some conflicting objectives should be considered. In this paper, the supplier selection problem is integrated with production decision and distributor location problems and a new mathematical model is proposed. Delivery time, total cost, and quality are the objective functions considered and weighting method is used to solve the multi-objective problem. A modified genetic algorithm is proposed to obtain Pareto optimal solution sets. Computational experiments are included for validation of proposed algorithm. The results show that the proposed algorithm gives high-quality solutions as well as better computational times.     

Planning performance based contracts of repairable system using discrete event simulation

This paper investigates a discrete event simulation approach for managing performance based contracts of repairable systems. We focus on an integrated service delivery environment where the manufacturer develops capital-intensive systems and also provides after-sales support. We propose a simulation model to calculate system availability comprehending four performance drivers: life time distribution, repair time distribution, spare parts inventory, and repair facility. This simulation model allows the service supplier to minimize the total cost by optimizing the four performance drivers. In this simulation model, the failure time and repair time can follow arbitrary distribution. This will allow the customer to monitor the supplier’s service through comparing the actual availability and its theoretical value. The costs of three maintenance policies also can be studied under the performance based contracts framework. Two cases are considered in this paper. One is a system containing single unit, one warehouse, and one repair center. Another is a system containing two fleets with different installed units, two spare part warehouses with one for each fleet, and a central repair depot.