外部市场存在替代产品的VMI系统研究

供应商管理用户库存(VMI)作为一种有效的补货机制,能对购买渠道的需求信息做出积极正确的反应.现在对VMI的研究往往集中于单个零售商和单个供应商组成的系统,不考虑VMI系统受市场上其他零售商或供应商的影响.假设市场上多个零售商出售相互之间可替代的产品,某个零售商与其供应商之间应用VMI系统.我们的研究主要有两方面:1)VMI系统是否有助于零售商和供应商组成的供应链在差异产品市场上获得更大的收益;2)供应商和零售商如何决策是否应用VMI系统。     

基于ROI,VMI和CS三种库存方式长短期绩效的对比研究

ROI、VMI和Cs是基于供应链的三种库存管理方式.本文以两层供应链的ROI、VMI和CS方式为例,通过数学模型和具体算例,比较分析了三种库存方式下买方和卖方成本和利润构成的不同之处.本文研究发现:在长期内相对于ROI方式而言,VMI方式下供应链的效率更高;如果卖方的单位存储成本大于买方,CS方式下供应链的长短期效率可能高于VMI更高于ROI方式.     

VMI策略下的综合生产计划研究

本重点研究了在供应链环境下，基于供应商管理客户库存(VMI)策略的供应商综合生产计划问题。模型综合考虑了供应链的存储费用、缺货损失和生产费用，提出供应链总成本最小目标模型，并采用搜索法结合线性规划给出了算例求解和分析结论。     

随机需求下供应商管理库存的供应链模型

以一个供应商和一个零售商的两阶段供应链为背景,利用报童模型给出了供应商管理库存(VMI)的供应链模型,在需求服从均匀分布的条件下得出解析解,并与传统的零售商管理库存(RMI)系统作了比较,分析了这两种情况下批发价和订货量的变化.数值结果表明VMI导致了批发价的缩减,但提高了订货量,VMI减轻了双重边际效应,系统利润多于传统的RMI系统.     

考虑横向整合战略的库存路径动态区域定价

库存路径和定价是供货商管理库存(Vendor Management Inventory, VMI)中三个互相制约和影响的决策问题,是降低供货商成本,提高其利润的关键。针对VMI拉式供应链中多供货商、多商品和多区域的库存路径定价问题,提出了对不同区域客户、在不同时段进行商品差异化定价策略,并设计一种共同配送车辆司机成本和燃油成本分摊方案,据此构建基于横向整合战略的库存路径动态区域定价模型。算例结果显示,在横向整合战略下,供货商商品定价会有所降低,配送车辆行驶距离显著缩短,各时段配货量更为均衡,期末库存数量显著降低。研究表明,无论供货商之间供货规模比例差异多大,开展库存路径动态区域定价,供货商联盟成员的利润均能得到显著提高,实现合作共赢的目标。     

一种考虑广告费对需求影响的供应商管理库存集成模型

降低供应链中处于不同阶段的物料(原材料、在制品以及成品)的库存水平已经成为供应链管理的研究焦点之一。其中供应商管理的库存VMI(vendor-managed-inventory)策略不论在理论上还是在不同企业的实践中都到了广泛的关注。本文首先给出了一个考虑一个供应商和多个不同的订货商,订货商有共同的订货补充期,并且考虑广告费对需求影响的VMI集成模型;其次,给出了模型的相应算法;最后,给出了算例加以说明。     

不同情形下供应链优化决策模型的比较分析

本文提出三种不同情形（制造商与零售商追求各自利润最大化，并且没有价格折扣策略；制造商与零售商共同追求总利润最大化，不实施价格折扣策略；制造商与零售商共同追求总利润最大化，并实施价格折扣策略）下供应链价格和库存补充策略的优化决策模型，并通过具体数例进行比较分析，结果表明，供应链合作并实施价格折扣策略时的供应链总利润最高，而供应链双方利润分配系数的变化对基于供应链总利润最大化的供应链优化决策没有影响．     

在允许缺货情况下的易变质产品供应商管理库存

本首先通过解析推导给出了一个考虑一个供应商和多个不同的订货商，并且允许订货商缺货的易腐商品供应商管理库存VMI(Vendor Managed Inventory)模型；其次通过mathematica4．2软件计算。给出了算例及其最优解，并通过灵敏度分析讨论了单位缺货成本和变质率对库存决策的影响；最后给出了总结，说明了研究的意义。     

需求率基于库存的变质物品的两货栈模型

针对需求受库存水平影响的变质品的两货栈系统,本文首先考虑了允许缺货但缺货要补情形下,分别给出了L₁系统(库存系统只用自己的货栈存放物品)和L₂系统(库存系统使用自己货栈和租用货栈存放物品)时,销售商的库存和运输策略模型。其次给出了允许缺货但缺货不补L₁系统和L₂系统时,销售商的库存和运输策略,并对模型最优解作了相关分析,最后给出算例,给销售商实际的库存管理提供了理论依据。     

2级VMI集成的Shapley指数收益分配方案

本文在回顾了VMI集成相关文献基础之上,将解决多人合作博弈问题的Shapley值方法用于解决两级VMI联盟的收益分配问题,从而提出了一种各方均可接受且稳定的收益分配方案.在此收益分配方案下,供应链各方均会从VMI集成中得到利润水平上的提升,而且兼顾到了各方公平.     

考虑需求率变化与延期支付的临时订货模型

供应商给予临时价格折扣、并针对采购商的临时订货给予优惠的延期支付条件;同时考虑到采购商的自身需求即为终端需求并对价格敏感,由于考虑需求量变化的同时考虑到时间因素,因此需求率实际上发生了改变。在这样的背景下,采购商在价格变化时刻面临两种选择:以低价购进大量货物或者放弃这个机会。本文以EOQ模型单位产品成本为参考,从成本节约最大的角度出发,分析了采购商临时订货量的确定过程,并用数例分析了参数变化对最优订货以及成本节约情况的影响。     

随机需求下有产能约束的技术创新策略研究

在随机需求和技术变革的环境下,基于有产能约束的单供应商-单零售商的供应链结构,研究供应商分销价格决策和技术创新策略以及零售商订货决策。建立了三阶段Stackelberg博弈模型,通过逆推方法求得了供应商最优分销价格和技术创新策略以及零售商最优订货量,深入探讨了供应商产能、新技术出现概率以及市场需求期望与波动分别对供应商、零售商和供应链整体利润的影响。结果表明当供应商产能不足时进行技术创新会提高供应商和供应链的利润,但零售商因间接承担供应商技术创新的投资成本而利润下降;当供应商产能过剩时进行技术创新则会降低供应商及供应链的利润,而零售商的利润增加。新技术出现概率增加会提高供应链各成员的利润;提高市场需求期望并减小市场波动对供应商及供应链有利,但可能会降低零售商的利润。     

Minimizing the Total Cost in an Integrated Vendor—Managed Inventory System

In this paper we consider a complex production-distribution system, where a facility produces (or orders from an external supplier) several items which are distributed to a set of retailers by a fleet of vehicles. We consider Vendor-Managed Inventory (VMI) policies, in which the facility knows the inventory levels of the retailers and takes care of their replenishment policies. The production (or ordering) policy, the retailers replenishment policies and the transportation policy have to be determined so as to minimize the total system cost. The cost includes the fixed and variable production costs at the facility, the inventory costs at the facility and at the retailers and the transportation costs, that is the fixed costs of the vehicles and the traveling costs. We study two different types of VMI policies: The order-up-to level policy, in which the order-up-to level quantity is shipped to each retailer whenever served (i.e. the quantity delivered to each retailer is such that the maximum level of the inventory at the retailer is reached) and the fill-fill-dump policy, in which the order-up-to level quantity is shipped to all but the last retailer on each delivery route, while the quantity delivered to the last retailer is the minimum between the order-up-to level quantity and the residual transportation capacity of the vehicle. We propose two different decompositions of the problem and optimal or heuristic procedures for the solution of the subproblems. We show that, for reasonable initial values of the variables, the order in which the subproblems are solved does not influence the final solution. We will first solve the distribution subproblem and then the production subproblem. The computational results show that the fill-fill-dump policy reduces the average cost with respect to the order-up-to level policy and that one of the decompositions is more effective. Moreover, we compare the VMI policies with the more traditional Retailer-Managed Inventory (RMI) policy and show that the VMI policies significantly reduce the average cost with respect to the RMI policy.     

需求依赖于服务水平的易变质品库存策略研究

本文研究需求依赖于上一周期服务水平、缺货时订单部分损失的两周期易变质品库存问题。分别考虑一次订货和多次订货两种情况,以平均利润最大化为目标构建库存模型,证明了模型解的存在性和唯一性,得到了最优库存服务水平和最优补货策略。最后,通过算例给出两个模型的应用,对重要参数进行了灵敏度分析,并且将两种模型的结果进行了对比分析。结果表明:订单损失率的增加会提高服务水平,但会使得利润降低;顾客期望服务水平的提高会降低第一阶段的服务水平,同时使利润减少;单位库存持有成本或变质率的增加会降低服务水平和平均利润。通常情况,企业通过多次订货能获得更大的利润,而只有当库存持有成本极小时,一次订购才能够获得更大的利润。同时,结果也表明:服务水平对库存策略有较大的影响,因此在进行库存决策时考虑服务水平具有重要的作用。     

Joint pricing and inventory replenishment decisions with returns and expediting

We study a single-item periodic-review model for the joint pricing and inventory replenishment problem with returns and expediting. Demand in consecutive periods are independent random variables and their distributions are price sensitive. At the end of each period, after the demand is realized, a buyer can return excess stocks to a supplier. Or, if there are stockouts, the buyer can place an expediting order at the supplier to reduce the amount of shortage. Unfilled demands are fully backlogged. We characterize the optimal dynamic policy that determines the pricing, inventory replenishment, and adjustment decisions in each period so that the total expected discounted profit is maximized. For a very general stochastic demand function, we can show that the optimal replenishment policy is a modified base-stock policy, the optimal pricing policy is a modified base-stock-list-price policy, and the optimal policy for inventory adjustment follows a dual-threshold policy. We further study the operational effect of returns and expediting. Analytical and numerical results demonstrate that returns and expediting lead to a significant profit increase in a number of situations, including limited supply capacity, sufficient flexibility of the expediting order, high demand uncertainty, and a price-sensitive market.     

需求随价格变化的具有折扣的易变质物品的库存模型

本文研究了在需求随价格变化及物品易变质的条件下，当供应商给予数量折扣时的库存问题。证明了当供应商给予数量折扣时，零售商的需求量是增大的，并给出了供应商给予数量折扣时零售商的订货量和订货周期的计算方法。对物品变质率和需求价格敏感系数对零售商的订货量、订货周期、出售价格和单位时间利润的影响进行了数值分析，并给出了数值算例。     

Mitigating supply risk: an approach with quantity flexibility procurement

This paper considers a buyer that procures from its major supplier whose production is subject to random yield risk. To mitigate supply risk, the buyer can procure from another reliable supplier who provides quantity flexibility (QF) contract. Under both deterministic and stochastic demand, we study the buyer’s optimal procurement decisions. We analyze the structural properties of optimal solutions and identify the conditions under which the quantity flexibility procurement policy should be used. We also examine the effect of supply risk, flexibility, wholesale price and demand risk on the procurement decisions. We find that the higher supply risk and demand risk reduce the buyer’s profit but have different impact on the buyer’s order policy. For the QF supplier, it may not obtain more orders by providing larger flexibility to the buyer, on the contrary, doing this may benefit the risky supplier. For the QF supplier or risky supplier, given its competitor’s wholesale price, it can increase its order share by lower wholesale price.     

Analysis of supply contracts with minimum total order quantity commitments and non-stationary demands

In this paper we address a buyer–supplier arrangement of particular importance: total order quantity commitment (TOQC). Under the TOQC contract that has been negotiated between the buyer and the supplier, the former agrees to an obligation to procure a certain quantity of an item from the latter over the predetermined period of time (additional quantity can be obtained maybe at a different price). The optimal inventory replenishment policy is shown to be dual order-up-to levels under a given TOQC, and the optimal TOQC is also demonstrated to be mathematically straightforward to obtain.