基于Stackelberg博弈的变质物品分销网络设计模型

研究了一类短销售期的变质物品的分销网络设计问题.假定零售商的缺货成本依赖于分配给为其提供服务的分销中心的库存成本,供应商在销售期末给零售商提供第二次订货机会,供应商根据零售商的订货决策确定分销中心的最优选址和确定每个分销中心为哪些零售商提供服务,从而最小化总的运作成本(选址成本,运输成本,库存成本和变质成本),其中分销中心的运输成本和库存成本依赖于零售商确定的订货数量;而零售商则根据供应商的决策确定自身的最优订货决策,利用Stackelberg博弈分析的方法,建立了一类变质物品的分销网络设计模型,并使用拉格朗日松弛算法求解,最后通过数值算例分析了模型最优解对于参数的敏感性.     

库存共享和服务水平限制下三级分销网络侧向转运模型与算法

侧向转运是库存共享的一种方式,一方面会减少库存成本,另一方面又会因转运而增加运输成本,针对这一问题考虑不同时间窗W^k的服务水平产生的服务水平的分级,构建三级分销网络中基于库存共享与时间服务水平限制的批量订货模型,分销网络模型中包含一个制造商、一个RDC、m个DC、n个客户。其中客户的需求相互独立且服从泊松分布,DC的订货提前期服从指数分布。首先,建立了基于时间服务水平限制的分销网络系统总成本最小化模型,并将再购点、订购批量等库存参数作为同时作为决策变量,以达到三级备件分销网络的成本优化;其次,根据问题和模型的特点对所建的模型开发了基于采用贪婪增加算法的求解思想求解问题,以便给管理者提供决策参考并通过降低利润的方式增加效益和资源利用率;最后,通过中航材集团推行的“航材共享”项目作为算例分析,将三个分销区域与机场群组成的备件分销系统进行建模分析,验证了本文模型的有效性,成本优化的显著性。研究结果表明,三级分销网络中,RDC采用连续盘点的（Q,R）补货策略、DC采用（Q,R,H）的补货策略时系统总成本与普遍采用的定期盘点策略和连续盘点中的One-for-One订货策略成本相比,DC之间的库存共享策略能有效降低整个系统的成本,例如,在案例研究中发现成本降低约为30%。     

替代品竞争环境下损失厌恶报童问题研究

通过分析2个零售商之间的竞争博弈,得出他们的均衡库存,研究了损失厌恶和产品替代率对零售商库存决策的影响。研究结果表明:存在替代品竞争的情况下,当缺货损失大于过量订货损失时,损失厌恶使得零售商库存和行业总库存增大;反之,损失厌恶使得零售商的库存和行业总库存减少;数值实验说明,当市场需求的分布不同时,产品替代率对零售商最优库存决策的影响不同,零售商在进行产品定位时,应考虑市场需求的分布。     

级库存(R,Q)策略的简单应用

考查由一个中心仓库和多个零售商构成的两级供应链配送系统,研究基于泊松需求假设的级库存(R,Q)策略的优化和应用.分析中心仓库在随机的提前期内的需求分布和缺货引起的零售商订货时延,提出优化级库存订货点的迭代计算算法.最后给出了具体的算例.     

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。     

一种减少供应链牛鞭效应的资产组合管理方法

考虑一个由单个供应商和多个零售商组成的供应链系统,零售商面临无促销活动和有促销活动两种动态需求环境,采用周期性检查库存策略,基于当前市场需求信息向供应商订货.同时,市场中的零售商由于订货决策行为的相互影响而存在一定的相关性.本文探讨零售商之间具有不同相关性订货决策时,运用资产组合管理方法调整零售商之间的供应量,减少订货的总方差,实现减少订货所产生牛鞭效应.随后,通过对比分析零售商订货量调整前后库存水平、库存成本、缺货损失和利润,验证了零售商调整订货量的动机和积极性.数值算例的结果表明,运用资产组合管理方法能够减少供应商的总方差,同时能够激励具有不同相关系数的零售商调整订货量,在一定程度上减少供应链中的牛鞭效应.零售商之间的相关系数越大,供应链中牛鞭效应减少的效果就越显著;且在同一相关系数下,零售商对市场需求预测的方差越大,运用资产组合管理方法所达到的牛鞭效应减少的效果就越大.     

基于信息更新与服务水平约束的供应链订货及协调决策

研究由一个供应商和一个零售商及一组顾客组成的单周期供应链系统。供应商向零售商提供两次订 货机会,零售商根据第一阶段的订货情况及市场信号,对需求信息进行更新预测,确定第二阶段是否需要补货。首先,通过分析顾客购买与退货决策,确定产品的最优零售价格与退货价格。其次,对零售商的订 货策略进行研究,以两阶段利润之和最大化为目标函数,引入服务水平约束,确定了零售商第一阶段和第 二阶段的最优订货量,并探讨了市场信号和服务水平约束对零售商最优订货策略及期望利润的影响。结果表明,当目标服务水平设定较低时,零售商的订货策略与不设定服务水平约束时的情形相同;但是无论是高目标服务水平还是低目标服务水平,若二次订货时点上的市场信号为低值时,零售商无需二次订货,而若此时点的市场信号为高值时,零售商需要进行二次订货,目标服务水平的高低将对第二次的订货量产生影响。最后,证明了基于差别定价的回购契约能够实现上述供应链系统的协调。     

供应不确定条件下多周期库存博弈

本文研究供应不确定条件下多周期二人库存博弈问题，证明了均衡库存策略的存在性，并刻画了均衡策略的特征，探讨了供应不确定和产品替代率对零售商库存决策的影响。研究结果表明：在供应不确定条件下，多周期库存博弈问题存在多重Nash均衡库存策略。当需求分布函数满足特定条件时，博弈存在唯一纳什均衡解。此外，本文证明均衡订货策略是产品替代率的增函数，供应可靠性高的商家更具有优势且收益更大。数值实验说明，供应不确定会直接影响均衡订货量。商家的期望收益和均衡订货量是自己供应可靠性的增函数，是对手可靠性的减函数，是产品替代率的增函数。     

混合分销渠道结构下短生命周期产品供应链库存策略分析

随着竞争的加剧,产品生命周期日渐缩短。信息和网络技术的不断进步,使得网络作为一种特殊的分销渠道出现。传统分销渠道和网上直销渠道并存的混合分销渠道结构给理论研究和管理实践提出了新的挑战,本文针对混合分销渠道结构下短生命周期产品供应链,运用报童问题的框架,分析了两种不同运作模式下生产商和零售商库存策略,并通过数值实验研究了需求不确定性对生产商和零售商最优库存策略的影响。最后,根据数值实验的计算结果,总结了本研究的管理启示。     

基于现金折扣和延期支付条件下变质产品的补货策略

针对变质产品,考虑产品非瞬时补货的情况下,在允许延期支付且如果零售商提前还款,供应商给予零售商现金折扣优惠的条件下,建立了相应的零售商库存决策模型。对模型进行求解,得出零售商的最优订货周期及最优付款时间。最后,通过具体算例,结合灵敏度分析方法,分析了模型中参数变化对最优订货策略的影响。     

Coordinating a Supply Chain System with Retailers Under Both Price and Inventory Competition

We investigate a supply chain system with a common supplier selling to downstream retailers who are engaged in both price and inventory competition. We establish the existence and uniqueness of the pure‐strategy Nash equilibrium for the retailer game and study how a supplier can coordinate the system to achieve the best performance. Our main conclusions are as follows: First, a buyback contract can be used to coordinate retailers competing on both price and inventory in a sense that optimal retail prices and inventory levels arise as the Pareto‐dominant equilibrium. With symmetric retailers, the system optimum arises as the unique symmetric equilibrium. Second, the particular type of competition experienced by retailers (price versus inventory competition) affects the characteristics of the contract. Specifically, strong price competition leads to a coordination mechanism with a positive buyback rate, where the supplier subsidizes retailers for leftover inventories; however, strong inventory competition leads to a negative buyback rate, where retailers are punished for overstocking. Using a linear expected demand function, we further explore the impact of system parameters on the coordination contract and the competitive equilibrium. We also find that the performance of the supplier's optimal contract is asymptotic to the system optimal coordination contract as competition becomes fierce.     

Differences in Retail Inventory Investment Behavior During Macroeconomic Shocks: Role of Service Level

In this article, we analyze how retailers change their inventory investment behavior in response to macroeconomic shocks. We examine if service level, as measured by the ratio of stockout to inventory holding costs, can explain the differences in observed behavior across retailers. We use data on macroeconomic indicators and quarterly filings of US public retailers from 1985 to 2009 to estimate a dynamic model of short‐ and long‐term impact of macroeconomic shocks on inventory investment. Our results show that retailers with a high service level increase their inventory investment significantly more than those with a low service level during expansion shocks. Conversely, retailers with a low service level curtail their inventory investment significantly more than those with a high service level during periods of economic contractions. Thus, we show that the aggregate change in inventory investment documented in prior macroeconomics research is driven by different sets of retailers, as predicted by newsvendor logic. We draw implications of our findings to retailers as well as their suppliers.     

Why Do We Observe Stockless Operations on the Internet? Stockless Operations Under Competition

Due to the proliferation of electronic commerce and the development of Internet technologies, many firms have considered new pricing‐inventory models. In this paper, we study the role of stockless (i.e., zero‐inventory) operations in online retailing by a considering duopoly competition in which two retailers compete to maximize profit by jointly optimizing their pricing and inventory decisions. In our model, the retailers are allowed to choose either an in‐stock policy or stockless operations with a discounted price. We first present the characteristics and properties of the equilibrium. We then demonstrate that the traditional outcome of asymmetric Bertrand competition is observed under head‐to‐head competition. However, when the two firms choose different operational policies, with corresponding optimal pricing, they can share the market under certain conditions. Finally, we report interesting observations on the interaction between pricing and inventory decisions obtained from an extensive computational study.     

On the benefits of operational flexibility in a distribution network with transshipment

We consider a centralized distribution network with multiple retailers who receive replenishment inventory to satisfy customer demand of the local markets. The operational flexibility of the network is defined as the opportunity that one retailer's excess inventory can be transferred to satisfy other retailers’ unmet customer demand due to stock-outs. A general modeling framework is developed to optimize retailers’ order quantities under any possible flexibility level of a stylized two-stage distribution network. We apply the framework to formulate and solve the transshipment problem of a distribution network with three retailers. Six typical flexibility levels are investigated to make the comparison study on the firm's profit performance under three ordering quantity policies: average demand, newsvendor order quantity, and optimal order quantity. We find that the operational flexibility and system optimization are complements to the firm's performance. The ordering policy with newsvendor ordering quantity can perform fairly well with moderate flexibility level when compared with the optimized ordering policy with full flexibility.     

区分仓库与货架库存需求影响效应的零售商库存决策

既往有关库存水平影响需求条件下的库存问题研究中,通常对终端库存水平是否存在货架与零售商仓库库存水平的区别未作深入探讨。本文的研究认为,现实中许多零售商拥有仓库,其现有库存水平包括仓库库存和货架库存两部分,而影响需求的仅为与货架展示能力相关的库存,因此有必要对二者的需求影响效应进行区分。在明确这一区别的前提下,本文首先建立了供应商管理库存情况下库存水平影响需求问题的一般库存模型,给出零售商的最优订货策略;并考虑货架的容量限制,给出零售商启用仓库的判断条件。由于仓库库存仅在能够影响货架展示能力的条件下才能够影响消费需求,本文还进一步讨论了在零售商拥有仓库时,区分货架与仓库的库存水平影响需求条件下的最优库存与订货决策。这对于经营不同特征商品的零售商在进行是否需要拥有仓库,以及拥有仓库条件下的库存决策具有很好的参考价值。     

基于“搭便车”行为的双渠道供应链库存竞争和促销策略

本文建立了由一个制造商和一个零售商组成的双渠道供应链模型，研究了随机需求下"搭便车"行为和渠道间缺货替代行为对供应链库存竞争与促销决策的影响。结果表明：分散式决策下，网络渠道替代率越高，零售商的最优订购量越大，同样的零售渠道替代率越高，制造商会为网络渠道提供更多的库存；而"搭便车"行为对零售商与制造商订购量的影响则取决于渠道替代率的变化，但"搭便车"行为会降低零售商促销努力水平。数值分析发现：分散式决策下，零售商最优订购量随"搭便车"行为的增加而减少。然而制造商的最优库存量并非随着"搭便车"行为程度的增加而增加，不同的是制造商网络渠道最优库存量取决于市场需求对传统零售渠道促销努力水平的弹性系数，即制造商网络渠道最优库存量随"搭便车"行为的增加先增加后减少。通过比较发现在不同的"搭便车"行为程度、传统零售渠道替代率、网络渠道替代率下，集中式决策下供应链期望收益大于分散式决策下供应链期望总收益。     

DECENTRALIZED MULTIECHELON INVENTORY CONTROL

This paper considers a model for decentralized control of an inventory system consisting of 1 central warehouse and a number of retailers. The cost structure includes holding costs at both echelons and shortage costs proportional to the time until delivery at the retailers. We analyze a procedure for coordinated but still decentralized control of the system. The procedure is based on a simple approximation, in which the stochastic lead times perceived by the retailers are replaced by their correct averages. The approximation enables us to decompose the considered multiechelon inventory problem into a number of single echelon problems, 1 for each installation. The information about how a certain decision at the warehouse affects the retailers is conveyed through the marginal cost increase with respect to a change of the expected lead time. This information about the retailer costs is used as a shortage cost at the warehouse. We show that a coordination procedure based on this information can be used for finding near-optimal reorder points for the system and provide bounds for the approximation errors.     

多渠道供应链中物流系统的容量扩充与分配模型

考虑一个传统供应链将市场由单一的实体商店零售扩大到互联网上的在线零售,为满足新增的在线零售需求,供应商需要扩充物流系统的供应容量,并设计新增容量的分配方案。本文针对由一个中心仓库和多个地区仓库组成的二级物流系统,在保留现有配送网络结构的基础上,构建了物流系统的容量扩充与分配模型,并提出一种基于拉格朗日松弛法的求解算法。我们通过数值实验表明了算法的有效性,并通过数值算例说明了运输成本与库存汇聚效应对最优容量扩充与分配方案的影响。