AN ALGORITHM FOR THE DETERMINATION OF THE ECONOMIC ORDER QUANTITY IN A TWO-LEVEL SUPPLY CHAIN WITH TRANSPORTATION COSTS： COMPARISON OF DECENTRALIZED WITH CENTRALIZED DECISION

This paper considers a two-level supply chain consisting of one warehouse and one retailer. In this model we determine the optimal ordering policy according to inventory and transportation costs. We assume that the demand rate by the retailer is known. Shortages are allowed neither at the retailer nor at the warehouse. We study this model in two cases; decentralized and centralized. In the decentralized case the retailer and the warehouse independently minimize their own costs; while in the centralized case the warehouse and the retailer are considered as a whole firm. We propose an algorithm to find economic order quantifies for both the retailer and the warehouse which minimize the total system cost in the centralized case. The total system cost contains the holding and ordering costs at the retailer and the warehouse as well as the transportation cost from the warehouse to the retailer. The application of this model into the pharmaceutical downstream supply chain of a public hospital allows obtaining significant savings. By numerical examples, the costs are computed in MATLAB to compare the costs in the centralized case with decentralized one and to propose a saving-sharing mechanism through quantity discount.     

Order decision making based on different statement strategies under stochastic market demand

Based on the stochastic market demand,this paper considers the order decision-making strategies of the supply chain by introducing statement strategies.Consequently,the time-variant variance in the demands of the market is incorporated into the model.The retailer simultaneously determines the purchase time(i.e.,lead time)and order quantity,and the manufacturer determines the statement strategy and the reserved profit rate.The results show that the no overtime statement strategy can induce the retailer to place more orders in advance by limiting the available order quantity within the available time.Finally,we also adopt numerical examples to support the conclusion of this paper.     

MANUFACTURER’S UNIFORM PRICING AND CHANNEL CHOICE WITH A RETAIL PRICE MARKUP COMMITMENT STRATEGY

The paper studies channel choice decisions in a multi-channel supply chain under a strategy where there is an ex-ante commitment made on the retail price markup. The market demand is uncertain and dependent on the price and sales efforts. The results show that in any channel structure, when making order decisions the retailer only examines the price ratio and the fluctuation size of random demand, rather than the channel cost and the retailer＇s marketing efficiency. When the retail price rises, the manufacturer is willing to increase inventory quantity for direct sales, because the manufacturer＇s profit margin is higher in direct channel. The increase in demand fluctuation only affects the degree of channel preference but doesn＇t change the manufacturer＇s channel choice. No matter in which level the price ratio is, when the sales efficiency of retail channel is not high or the demand proportion of direct channel is low, the manufacturer and the retailer will be both apt to choose a dual-channel structure. Then adding a direct channel becomes a marketing strategy, rather than a competitor of the retail channel, and helps the supply chain win more market demand.     

Outsourcing decision and order policy with forecast updating under capacity reservation contract

This paper investigates an optimal decision problem in a single-period, two-stage supply chain with capacity reservation contract. At the beginning of the planning horizon, the retailer, who faces stochastic demand, reserves future capacity according to his forecasting of the demand. The supplier then constructs capacity. At the beginning of the selling season, the retailer updates the demand forecasting and places an order. When the retailer＇s demand is greater than the supplier＇s capacity, the supplier can meet the retailer＇s demand by outsourcing. We analyze the optimal decision of each player in both centralized and decentralized systems. Furthermore, under the case in which demand follows a uniform distribution, we obtain the closed-form optimal strategies of each player for both centralized and decentralized systems and conduct numerical studies to reveal additional conclusions. The numerical studies show that the optimal reservation capacity for the retailer and the optimal constructing capacity for the supplier in the decentralized system are both less than the optimal constructing capacity in the centralized system. Furthermore, we also find that the profit loss due to decentralization always exists and increases in indeterminacy.     

Study on the Stability of Supply Chain System Under Perturbations of Dynamic Parameters

The stability of supply chain system is key to implement efficiently inventory policies and improve quality of service in the supply chain. If the supply chain system were unstable, the lead-time would be uncertain. As a result, directly affects the process of manufacture, and the service level. In this paper, we analyze the stability of the supply chain system under perturbations of dynamic parameters based on the Cobb-Douglas production function and study influences on supply chain performance. We prove that the supply chain system, with the increases of the re-production input funding, becomes unstable. Further, when the optimal combination of input parameter elements, the supply chain system becomes unstable.     

Manufacturers' Channel Competition with Retailer Demand-Enhancing Service

Manufacturers’channel competition with service is examined in this paper.Specifically,the authors consider channel competition within a supply chain comprising two manufacturers and one single retailer where each manufacturer can choose to sell its products either directly to the end market(online channel,say)or through the potential retail channel,based on the profit maximization criterion,which is influenced by exogenous market conditions,such as the degree of competition,etc.Furthermore,the retailer provides additional demand-enhancing service to promote the manufacturer’s products distributed via it.If only one of the manufacturers sells products through the retailer,its products will be promoted by the additional retail service,which poaches demand of products of the manufacturer who adopts direct online channel.Products of both manufacturers are supported by the retailer’s promotional service when both distribute their product through the common retailer.Finally,some managerial implications are derived from numerical analyses of our model,which explain the phenomena in practice and conclude the paper.     

Collaborative supply chain planning under dynamic lot sizing costs with capacity decision

Studies show that supply chain cooperation improves supply chain performance. However, it remains a challenge to develop and implement the realistic supply chain cooperation scheme. We investigate a two-echelon supply chain planning problem with capacity acquisition decision under asymmetric cost and demand information. A simple negotiation-based coordination mechanism is developed to synchronize production/order strategies of a supplier and a buyer. The coordination scheme shows how the supplier and the buyer modify their production and order policy in order to find a joint economic lot sizing plan, which saves the overall supply chain cost. The allocation of the cooperation benefit is determined by negotiation. Due to the complexity of the multiple periods, multiple level supply chain lot sizing with capacity decision, a heuristic algorithm is developed to find coordination solutions. Finally, the results of the numerical study indicate the performance of supply chain coordination scheme.     

Strategic Response to a Powerful Downstream Retailer:Difference-Setting Wholesale Pricing Contract and Partial Forward Integration

We study a supply chain consisted of a supplier and both retailers,and the supplier sells a single product through a dominant retailer and a weak retailer.The aggressive bargaining behavior of the dominant retailer brings the supplier much concern and two feasible strategies are presented to respond to that:difference-setting wholesale pricing contract and integration with the weak retailer.We investigate the decisions of supply chain members under each solution and find that,compared to the traditional form,the supplier always benefits from announcing the difference-setting wholesale pricing contract for it not only raises the marginal wholesale profits of both channels but also reduces the market share of the dominant retailer,thus potentially weakening its channel power.In addition,we show that combining with the weak retailer is not a wise choice for suppliers when the dominant retailer with relatively little bargaining power enjoys a large market share.Finally,by comparing the equilibria of these two solutions,we find that the optimal choice for suppliers depends not only on the difference in market share but also on the dominant retailer's bargaining power in the negotiation.     

Information structures and pricing decisions in competing supply chains

The paper investigates the pricing decisions of two competing supply chains under the different information structures. Each retailer has private information about the market demand and has the right to decide whether or not to share the information with the manufacturer. Three demand-information structures, i.e., information sharing in both supply chains, information sharing in only one supply chain and information sharing in neither supply chain, are considered. We investigate the value of information by comparing the information structures, and find that the information value not only works in the channel directly, but also does in the competing channel indirectly. Information sharing in a supply chain always benefits its manufacturer, but hurts its retailer; while it benefits both the manufacturer and the retailer of competing supply chain, regardless of whether this competing supply chain has information sharing. From the perspective of channel, when the competition is more intense, information sharing in a supply chain makes this supply chain better off, and when the competition is less intense, the information sharing in a supply chain makes this supply chain worse off. However, it always makes the competing supply chain better off regardless of whether the competing supply chain has information sharing.     

竞争市场中的库存共享实施策略

零售商间的竞争使市场中的库存共享和转运实施变的困难,这造成极大的资源浪费.为实现竞争厂商间的库存转运共享,本文设计了一类由生产商主导的库存转运机制,进而分析转运系统的协调策略.假设市场需求随机且存在顾客转移,考虑两销售周期,针对由单生产商、两零售商组成的供应链系统.首先建立Stackelberg-Nash均衡博弈策略模型刻画供应链分销系统;其次设计生产商主导的竞争零售商主动转运机制;运用博弈分析方法分别给出分散式无转运、分散式转运及集中式转运系统的最优生产、订货、补货及转运等均衡策略;设计了一类由调货价合同、批发价合同、加盟费合同组成的组合协调机制,以实现分散式分销系统的协调及效率改进.研究及分析表明:生产商主导的协助转运机制能实现竞争零售商间的主动库存转运和共享;合理批发价、调货价、加盟费等设置下的组合协调合同能够实现供应链转运分销系统的完美协调.研究为企业科学开展库存决策提供了依据.     

集群式供应链跨链间的库存协调模型研究

以两单链的集群式供应链为背景,考察一供应链零售商的紧急库存补充渠道来自于另一供应链零售商的跨间库存协调问题。建立了没有单链(补充链)约束和存在单链约束条件下的跨链间库存合作模型。并用系统优化理论来寻求被补充供应链的正常渠道订货量和紧急补充量,以达到降低库存水平,提高整体利润。通过实例分析发现:商品零售价格和库存费率较高,以及订货间隔期短,紧急库存补充价格较低时,有促使集群供应链跨链间库存协作的倾向。     

单周期随机需求下基于协调策略的供应链库存系统可靠性研究

供应链是典型的需要协调的系统。在需求不确定的商业环境中,由于很难对消费需求做出准确而有效的预测,从而造成库存的积压风险与缺货风险。如何在不确定需求的市场环境下采用合理的库存策略,以提高供应链库存系统的可靠性是供应链管理的一个核心问题。本文从三种不同库存策略的角度研究了在随机需求条件下供应链库存系统可靠性,并通过算例验证了其有效性。     

集群式供应链跨链库存应急互补的仿真和优化

基于系统动力学,考察一供应链应急库存补充来自于另外其他相邻供应链,也即集群式供应链.对两供应链中两零售商跨链间的库存应急互补进行建模和仿真.在此基础上,通过改变库存满足销售周期,以及将单级跨链互补扩展到两级和三级跨链互补,来优化和改善库存管理.研究发现,当同时存在三级(供应商商、生产商和零售商)跨链库存互补时,集群式供应链的两单链库存平均值和波动幅度大为减少,并且两链的顾客需求满足率均得到较大提高.最后,设计出了一种混合式契约,来实现这种集群式供应链跨链间库存应急互补的协调和合作.     

1:1的二级非一体化供应链库存运输联合优化模型

研究了非一体化供应链下单供应商-单零售商的库存运输联合优化问题,考虑了一体化的理想情况以及运输成本分别由供应商、零售商承担3种情况,并建立了数学模型.随机数据实验验证了零售商承担运输成本情形可获得较优的供应链整体利润,其值接近于理想情况下供应链的总体利润,进而采用利润分配策略,以确保供应商和零售商双方均能获得更大利润,从而促进供应链协调.数值算例和参数灵敏度分析验证了运输成本由零售商承担策略的优越性和稳定性.     

考虑利他行为偏好的动态增长环供应链微分博弈

针对一制造商和一零售商组成的动态闭环供应链系统，分别构建了制造商利他、零售商利他以及双方利他3种行为模式下的Stackelberg微分博弈模型，借助贝尔曼连续型动态规划理论得到了3种利他模式下，制造商的回收努力投入和批发价格策略、零售商的产品销售价格策略、废旧产品回收率以及成员的值函数并进行了对比分析。算例验证了先前结论，进一步分析了制造商利他系数和零售商利他系数对稳态指标的影响，并以自立情形为基准模型，对比分析了3种利他模式下的供应链绩效时间演进规律。研究表明：利他行为是一种正向的社会偏好；制造商的利他行为能够有效地减缓供应链的双重边际效应，提高消费者剩余；零售商的利他行为虽会提高制造商利润，但却以牺牲自身利润为代价，也会使消费者需求量对价格的变动更为敏感；相比之下，双方利他行为是供应链的最优行为模式，可以带来经济、环保、社会三位一体总绩效的提升。     

供应链系统中零售商横向转载的随机规划模型及算法

为了研究随机需求下供应链系统中多零售商的横向转载问题, 提出了一种基于随机规划方法的多零售商横向转载模型, 并设计了一种启发式算法用于模型求解.考察由一个外部供应商和多个零售商组成的供应链系统, 供应商和零售商均采用order-up-to方法控制库存, 零售商面临随机性需求且相互之间存在横向转载.在横向转载经典假设条件下, 构建了以供应链总成本为目标的混合0-1规划模型.考虑到该模型中存在随机变量, 将模型转化为随机期望值规划模型进行求解, 结合随机拟梯度算法及遗传算法设计了一类启发式算法来求解模型, 给出了详细的求解过程.利用数值算例的仿真结果验证了模型及算法的有效性, 还就需求相关程度的影响及转载假设条件的影响进行了详细分析.研究结果表明:模型及算法对存在横向转载的供应链系统确定最优库存水平是相当有效的.     

考虑零售商营销投入的退化品整合库存模型

在整合库存模型的基础上考虑了商品具有退化特性并且将零售商的营销投入水平作为模型的内生变量,讨论从供应链系统整体利益出发,如何制定最优的生产、订货以及营销投入决策.给出了这一问题的求解算法,并通过数值研究分析了需求对营销投入敏感性的变化以及商品退化率的变化如何影响系统的最优策略与利润.     

不确定环境下损失厌恶零售商的提前支付决策

本文考虑由一个供应商与一个零售商组成的两级供应链.供应商为风险中性,零售商具有损失厌恶风险态度.在销售期开始前,零售商面临需求不确定性和供应不确定性,需要做出订货决策.本文从零售商角度出发,研究采用提前支付策略以降低供应不确定性风险.研究表明,在给定提前支付前提下,资金成本越低零售商的提前支付比例越高;当资金成本超过临界值时,零售商不再采取提前支付策略.零售商的最优订货量随损失规避偏好系数的增大而减少.论文也探讨了需求随机变化、紧急订货选择对系统绩效的影响.