库存影响需求下基于两层延期支付策略的供应链库存模型

研究一类货架和仓库商品共同影响需求的库存问题,采用二层延期支付策略,即供应商向零售商提供延期支付期,同时零售商也向顾客提供延期支付期;建立了相应的库存模型,得到零售商最优订购策略存在的条件及算法,最后给出数值例子和灵敏度分析.     

库存展示量影响需求的促销易腐品最优订货策略

零售商经常会选择多种商品进行促销以提高收益,促销商品与人民群众的日常生活密切相关。本文建立库存影响需求的促销易腐品的订货决策模型,允许缺货发生,且短缺拖后率与已经发生的缺货量和等待时间相关。证明了最优解的存在性和唯一性,提出了求解最优订购策略的搜索算法。通过仿真实验验证模型和算法,得到主要参数的灵敏度分析结果。     

考虑变质量可折价回购与库存水平影响需求的易变质品库存模型

考虑到易变质商品在一个销售周期内会有一定数量的商品发生变质,构建了一个考虑在一个销售周期内所产生的变质数量可折价回购以及库存水平影响需求的易变质品的库存模型,而且针对销售周期内的缺货数量,模型假定采取部分延迟订购的策略。针对这一模型,给出了平均利润函数并证明了其存在最优解,然后通过算例完成了不同销售价格、不同折价回购比例和不同库存影响因子条件下的最优订货策略的确定以及其余相关参数的灵敏度分析,分析结果可对零售商的订货策略有一定的参考价值.     

基于Backroom Effect的生鲜品零售库存决策优化

本文基于传统的Backroom Effect,考虑生鲜品零售中普遍存在的现象——仓库较之货架具有更为优越的腐损控制和保鲜能力,重新定义了仓库在保管生鲜品过程中存在的数量与保鲜方面的双重Backroom Effect。基于此,面向生鲜品零售商,研究包括仓库-货架补给决策以及订货补给的库存决策优化问题,并利用数值算例剖析了Backroom Effect下,货架与仓库存在的腐损率差异对零售商库存决策和相应利润的影响。文章的主要结论包括:生鲜零售商应在零售库存决策中充分考虑Backroom Effect的影响,借助其提高生鲜品的最优订货量,从而带来单位时间平均利润的提升;随着Backroom Effect效果的提升,零售商的最优订货量和对应的平均利润也随之增加;不同品类的生鲜品对Backroom Effect的敏感程度不同,零售商在进行仓库保鲜投资时应优先投资更易腐损且具有更高边际利润的生鲜品品种。     

在中心仓库有损失销售的二级分布库存管理模型的研究

通过对一个中心仓库和N个零售商的二级分布库存系统进行分析,采用基本(S-1,S)库存策略,综合运用了排队法和M ETR IC近似法,提出了一种在中心仓库有损失销售的二级库存管理模型,该模型描述在中心仓库缺货情况下,多数零售商不等待延期付货,而直接与供应商订货,导致中心仓库就会因损失销售而产生机会成本.该模型可达到二级分布库存系统的总成本最小.     

两层次延期支付且具有随机缺陷率产品的订购策略

传统的经济订货批量模型通常假设产品质量完好无损,但由于自然灾害、运输破损等不确定因素,因而实际情况非常少见,另外考虑了两层次延期支付,其中供货商提供给批发商延期支付期策略,同样批发商提供给零售商延期支付策略,建立了在商业信用条件下具有随机缺陷率产品的库存决策模型,然后得出批发商在不同情况下的最优订货周期、订购数量的简单判定方法.最后,通过算例说明了所得结论,并分析了参数变化对模型最优解的影响.     

存货影响销售率的无形变质物品库存控制模型

为解决存储过程中价值易发生贬值的一类无形变质物品最优订货问题,建立了一种存货影响销售率的无形变质物品库存控制模型.针对零售商期初订货批量的不同水平,以库存总成本最小为优化目标,分别求得了无形变质物品库存总成本函数.鉴于这些函数中的主要部分属于超越函数,函数性质不易探明,最优解难以直接求得.为此,从严格的数学证明出发,深入探讨了函数最优解的存在性和惟一性,为进一步研究提供了理论基础.最后,通过数值算例,系统分析了模型参数对库存总成本、期初订货批量和库存更新周期的影响,并结合实际对其结果的合理性进行了解释说明.     

数量折扣契约下制造商与零售商库存合作联盟的稳定性

针对实际中存在的不同形式合作联盟,研究了零售商库存合作联盟,以及制造商与零售商库存合作联盟所形成混合合作联盟的稳定性。在随机需求情况下,制造商通过自身中心仓库向多个零售商提供数量折扣契约,首先证明了两个合作联盟的最优运作决策都存在且唯一,并给出了制造商向零售商库存合作联盟提供数量折扣契约的形式,然后分析了两种合作联盟的稳定性,并得出混合合作联盟的总期望利润要高于零售商库存合作联盟的结论。     

快速补货模式下的动态定价与库存联合策略

在供应有限的情况下,研究常规补货和快速补货下商品动态定价问题.首先,建立了动态规划模型,理论证明了最优库存策略是基于(s,S)策略下改进的基本库存策略.其次,提出了一种启发式策略求复杂系统的最优策略,启发式算法能够求出最优价格和最优库存水平.最后,数值算例研究表明,库存管理中采用快速补货提高了零售商的利润;初始库存水平越高零售商的利润越高.     

基于信用支付和现金折扣的变质物品库存模型

本文在供应商提供给零售商定期信用支付和现金折扣情况下,研究了零售商的变质物品最优库存问题。基于信用支付和现金折扣的两种支付条件下,分四种情况建立库存模型,并给出了寻求变质物品最优订购周期和最优付款时间的有效算法。最后,给出算例以及最优解,以说明本模型及求解过程。     

Optimal ordering and transfer policy for an inventory with stock dependent demand

This paper deals with an ordering-transfer inventory model to determine the retailer’s optimal order quantity and the number of transfers per order from the warehouse to the display area. It is assumed that the amount of display space is limited and the demand rate depends on the display stock level. The objective is to maximize the average profit per unit time yielded by the retailer. The proposed models and algorithms are developed to find the optimal strategy by retailer. Numerical examples are presented to illustrate the models developed and the sensitivity analysis is also reported.     

Consignment contracting: Who should control inventory in the supply chain?

Consignment is a popular form of business arrangement where supplier retains ownership of the inventory and gets paid from the retailer based on actual units sold. The popularity of such an arrangement has come with some continued debates on who should control the supply chain inventory, the supplier or retailer. This paper aims at shedding light on these debated issues. We consider a single period supply chain model where a supplier contracts with a retailer. Market demand for the product is price-sensitive and uncertain. The supplier decides his consignment price charged to the retailer for each unit sold, and the retailer then chooses her retail price for selling the product. We study and compare two different consignment arrangements: The first allows the retailer to choose the supply chain inventory, together with her retail price, and is labeled as a Retailer Managed Consignment Inventory (RMCI) program; and the second calls for the supplier to decide the inventory, together with his consignment price, and is labeled as a Vendor Managed Consignment Inventory (VMCI) program. We show that with an RMCI program, the supply chain loses at least 26.4% of its first-best (expected) profit, while with VMCI, it loses just or no more than 26.4% of the first-best profit. Second, we demonstrate that both programs lead to an equal split of the corresponding channel profit between the supplier and the retailer. These results indicate that it is beneficial both to the supplier and to the retailer when delegating the inventory decision to the supplier rather than to the retailer in the channel.     

A two-echelon inventory model with lost sales

This paper considers a single-item, two-echelon, continuous-review inventory model. A number of retailers have their stock replenished from a central warehouse. The warehouse in turn replenishes stock from an external supplier. The demand processes on the retailers are independent Poisson. Demand not met at a retailer is lost. The order quantity from each retailer on the warehouse and from the warehouse on the supplier takes the same fixed value Q, an exogenous variable determined by packaging and handling constraints. Retailer i follows a (Q, R_i) control policy. The warehouse operates an (SQ, (S − 1)Q) policy, with non-negative integer S. If the warehouse is in stock then the lead time for retailer i is the fixed transportation time L_i from the warehouse to that retailer. Otherwise retailer orders are met, after a delay, on a first-come first-served basis. The lead time on a warehouse order is fixed. Two further assumptions are made: that each retailer may only have one order outstanding at any time and that the transportation time from the warehouse to a retailer is not less than the warehouse lead time. The performance measures of interest are the average total stock in the system and the fraction of demand met in the retailers. Procedures for determining these performance measures and optimising the behaviour of the system are developed.     

存货质押融资模式下的供应链协调

针对供应商、零售商和银行组成的供应链金融系统,研究了存货质押融资模式下的供应链协调。零售商作为中小企业,资金有限,需要向银行申请贷款,然而零售商信用较低难以获得融资。供应商作为供应链的核心企业,采用含有回购价格和回购比例的回购契约为零售商提供担保,使得零售商融资得以实现。分析了不确定需求下供应链金融系统,供应链以及零售商的最优决策,给出了融资情况下供应链协调的条件,指出了在供应链协调情况下批发价格和回购策略对供应链收益分配的影响,说明了回购的作用:一方面使零售商易于获得银行融资,另一方面使供应链协调得以实现,指出了质押率、贷款利率和零售商自有资金等参数对最优决策的影响。数值算例验证了理论分析结果。     

A periodic-review inventory control policy for a two-level supply chain with multiple retailers and stochastic demand

We consider a time-based inventory control policy for a two-level supply chain with one warehouse and multiple retailers in this paper. Let the warehouse order in a fixed base replenishment interval. The retailers are required to order in intervals that are integer-ratio multiples of the base replenishment interval at the warehouse. The warehouse and the retailers each adopt an order-up-to policy, i.e. order the needed stock at a review point to raise the inventory position to a fixed order-up-to level. It is assumed that the retailers face independent Poisson demand processes and no transshipments between them are allowed. The contribution of the study is threefold. First, we assume that when facing a shortage the warehouse allocates the remaining stock to the retailers optimally to minimize system cost in the last minute before delivery and provide an approach to evaluate the exact system cost. Second, we characterize the structural properties and develop an exact optimal solution for the inventory control system. Finally, we demonstrate that the last minute optimal warehouse stock allocation rule we adopt dominates the virtual allocation rule in which warehouse stock is allocated to meet retailer demand on a first-come first-served basis with significant cost benefits. Moreover, the proposed time-based inventory control policy can perform equally well or better than the commonly used stock-based batch-ordering policy for distribution systems with multiple retailers.     

部分延期付款下易腐品联合经济订货批量模型

针对易腐品供应链的联合库存决策问题展开研究.假设供应链内存在唯一的供应商和零售商,供应商提供商业信用期给零售商,但零售商需要在收到订货后,立即交付部分货款,且零售阶段由于条件限制,产品存在常数腐败率,而联合决策模型的目标是确定供应商的订货量乘数n和零售商的订货周期使得供应链的总成本最低.通过建立该问题的数学模型,证明了目标函数的性质,说明当给定n时,目标函数在每种情况下都存在唯一最优解.以此为基础,给出了相应的求解算法对该联合批量决策模型进行了求解.最后,结合运作管理实践,并通过数值算例说明了模型的有效性.     

Stock Rationing in a Continuous Review Two-Echelon Inventory Model

In this paper we consider a 1-warehouse, N-retailer inventory system where demand occurs at all locations. We introduce an inventory model which allows us to set different service levels for retailers and direct customer demand at the warehouse. For each retailer a critical level is defined, such that a retailer replenishment order is delivered from warehouse stock if and only if the stock level exceeds this critical level. It is assumed that retailer replenishment orders, which are not satisfied from warehouse stock, are delivered directly from the outside supplier, instead of being backlogged. We present an analytical upper bound on the total cost of the system, and develop a heuristic method to optimize the policy parameters. Numerical experiments indicate that our technique provides a very close approximation of the exact cost. Also, we show that differentiating among the retailers and direct customer demand can yield significant cost reductions.     

顾客部分延期付款下两级商业信用易腐品订货策略

针对易腐品的经济订货批量问题展开研究。在供应商给零售商提供延迟还款的同时,零售商也给顾客提供部分延期还款条件。分五种情况分别讨论零售商的成本构成,并由此建立数学模型以求解最优订货周期使得零售商单位时间总成本最小化。通过数学证明得到了目标函数的解析性质,结果显示每种情况下在可行域范围内至多存在一个极小值点。以此为基础给出了相应的命题以有效地确定零售商的最优决策。最后通过数值算例说明了模型的有效性。     

基于二层信用策略的两货栈库存模型

假设供应商向零售商提供信用支付期的同时,零售商也向顾客提供信用支付期,研究了两货栈的变质物品库存模型,并讨论了模型最优解的唯一性,最后给出了最优订购策略的算法步骤与数值例子.     

A stochastic periodic review integrated inventory model involving defective items, backorder price discount, and variable lead time

The purpose of this article is to investigate a stochastic integrated supplier-retailer inventory problem. The model analyzed in this article explores the problem of the protection interval, the backorder price discount, the lead time, and the numbers of shipments from the supplier to the retailer in one production run as control variables to widen applications for an integrated periodic review inventory model. We consider the situation in which the supplier and the retailer establish a long-term strategic partnership and contract to jointly determine the best strategy. We assume that the protection interval demand follows a normal distribution. Our objective is to determine the optimal review period, the optimal backorder price discount, the optimal lead time, and the optimal number of shipments from the supplier to the retailer in one production run, so that the joint expected annual total cost incurred has the minimum value. Furthermore, an algorithm of finding the optimal solution is developed. Also, the sensitivity analysis included and a numerical example is given to illustrate the results of the proposed model.