需求替代情形下反应能力的价值分析

本文通过对竞争报童模型加以拓展以研究需求替代情形下企业运用反应能力产生的价值。文中考虑了两种不同的需求结构:第一种中企业总需求是竞争双方库存量的分段线性函数,第二种中企业总需求的均值是双方库存水平任意形式的函数。根据需求结构的不同,建立了不同的库存竞争模型并提出了相应的均衡库存策略。基于这些均衡结论,进一步探讨了反应能力的价值。分析表明运用反应能力能在降低企业库存水平的同时提高顾客服务水平。此外,在不同的需求结构下,运用反应能力产生的价值均随可用反应能力以及缺货惩罚成本递增,而随单位反应能力的使用成本递减。     

具有多元马氏需求的多产品多阶段库存优化模型

本文研究一类新的多产品库存控制策略,即具有多元马氏需求特征的多产品多阶段的订货点订货量(Q, R, SS)策略,该策略考虑市场需求在不同产品之间具有多元马氏转移特征,并考虑缺货因素设置安全库存。论文首先建立了多产品多阶段的多元马氏需求预测模型,并通过该模型确定了各种产品需求之间的关系。同时,在该模型的理论基础上,提出了多产品多阶段的总期望成本模型及其最优(Q, R, SS)策略,进而结合算例给出模型的最优策略的数值解。     

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.     

Combined Pricing and Portfolio Option Procurement

In this paper, we study a single‐product periodic‐review inventory system that faces random and price‐dependent demand. The firm can purchase the product either from option contracts or from the spot market. Different option contracts are offered by a set of suppliers with a two‐part fee structure: a unit reservation cost and a unit exercising cost. The spot market price is random and its realization may affect the subsequent option contract prices. The firm decides the reservation quantity from each supplier and the product selling price at the beginning of each period and the number of options to exercise (inventory replenishment) at the end of the period to maximize the total expected profit over its planning horizon. We show that the optimal inventory replenishment policy is order‐up‐to type with a sequence of decreasing thresholds. We also investigate the optimal option‐reservation policy and the optimal pricing strategy. The optimal reservation quantities and selling price are shown to be both decreasing in the starting inventory level when demand function is additive. Building upon the analytical results, we conduct a numerical study to unveil additional managerial insights. Among other things, we quantify the values of the option contracts and dynamic pricing to the firm and show that they are more significant when the market demand becomes more volatile.     

Updating Inventories of Substitutable Resources in Response to Forecast Updates

We show simple yet optimal results to update the inventory/capacity levels, expected profit, fill rates, and service levels of substitutable resources in response to an updating of the mean demand forecasts for the resources. We find that a change in the mean demand of one resource does not affect the optimal inventory level of any other resource. The results are obtained for demands with location‐scale distribution, and for a revenue structure satisfying a triangle property such that the manager will always use the inventory of a resource to meet her own demand first before using it for substitution. The results for updating the performance measures also extend to managers who maintain non‐optimal inventory/capacity levels. Implications for procurement, sales and operational planning, and multi‐store operations are discussed.     

考虑交易安全风险控制投入的在线旅游供应链网络均衡模型

基于包括供应商、平台和消费市场的三层供应链网络结构，利用变分不等式刻画均衡态时在线旅游供应链网络各成员的最优经济行为，以及平台交易安全风险控制投入对供应链平台企业、供应链整体的风险水平和期望收益的影响。研究发现，在平台企业风险控制投入相同情况下，平台和消费市场的产品交易数量和价格大致相同，验证了模型的合理性和有效性。其次，随着交易安全风险控制投入的增加，平台自身交易安全风险下降，供应链网络整体的交易安全水平和交易数量上升，但平台自身的期望收益下降。最后，随着更多的平台加入，平台的期望收益下降，市场需求价格下降，消费者获利。但部分平台企业的搭便车行为，会导致供应链整体的交易安全风险水平上升。     

Optimal Planning Quantities for Product Transition

The replacement of an existing product with a new one presents many challenges. In particular, uncertainties in a new product introduction often lead to extreme cases of demand and supply mismatches. This paper addresses inventory planning decisions for product upgrades when there is no replenishment opportunity during the transition period. We allow product substitution: when a company runs out of the old product, a customer may be offered the new product as a substitute. We show that the optimal substitution decision is a time‐varying threshold policy and establish the optimal planning policy. Further, we determine the optimal delay in a new product introduction, given the initial inventory of the old product.     

考虑策略性消费者的生鲜农产品定价和库存决策

消费者的策略性行为使零售商的生鲜农产品的定价和库存决策面临更大挑战。本文基于报童模型,综合考虑消费者的策略性行为,对生鲜农产品价值下降进行离散化处理。刻画策略性消费者的决策行为,构建零售商的单阶段和两阶段定价及库存决策模型,分析了产品价值剩余率对消费者行为、零售商最优定价、最优库存水平以及零售商利润的影响机理。研究发现,在单阶段模型中零售商最优价格和最优库存水平均随产品价值剩余率的递增而递增;而在两阶段模型中,第二阶段最优价格随价值剩余率的变化趋势可能存在阈值。     

应对突发事件的库存共享策略

以包含两个销售商的库存系统为例,构建了一个描述库存共享应对突发事件的非合作博弈模型,证明了其纳什均衡解是唯一存在的。研究结果显示库存共享策略总有可能使得销售商的期望利润得以改进。另外,比较静态分析反映了转载价格和转载成本显著影响库存共享销售商的最优订货量和最优期望利润。最后,提出了一个简单的求解模型纳什均衡解的启发式算法。     

Dynamic Pricing and Inventory Management with Regular and Expedited Supplies

We consider a periodic‐review inventory system with regular and expedited supply modes. The expedited supply is faster than the regular supply but incurs a higher cost. Demand for the product in each period is random and sensitive to its selling price. The firm determines its order quantity from each supply in each period as well as its selling price to maximize the expected total discounted profit over a finite or an infinite planning horizon. We show that, in each period if it is optimal to order from both supplies, the optimal inventory policy is determined by two state‐independent thresholds, one for each supply mode, and a list price is set for the product; if only the regular supply is used, the optimal policy is a state‐dependent base‐stock policy, that is, the optimal base‐stock level depends on the starting inventory level, and the optimal selling price is a markdown price that decreases with the starting inventory level. We further study the operational impact of such supply diversification and show that it increases the firm's expected profit, reduces the optimal safety‐stock levels, and lowers the optimal selling price. Thus that diversification is beneficial to both the firm and its customers. Building upon these results, we conduct a numerical study to assess and compare the respective benefit of dynamic pricing and supply diversification.     

Late season low inventory assortment effects in the newsvendor problem

The assumption of the newsvendor being able to satisfy demand as long as on-hand inventory is positive does not hold for a non-homogenous product. Consumers who do not find a unit of the product which satisfies their secondary features preferences may not purchase the product even though the newsvendor has positive on-hand inventory. This is likely to occur late in the season as inventory level declines. We solve a newsvendor problem in which the probability of purchase by consumers is increasing in on-hand inventory for any inventory level below that which is needed to have a complete assortment. We identify the sufficient optimality condition for the order quantity. We show that, unlike the case of inventory-dependent demand models in the literature, the optimal order quantity may decrease due to the assortment effect. We investigate two types of pre-end of season discounts, immediate all-units and delayed, as ways to mitigate the late season assortment effect and show that in some cases, they can increase the newsvendor׳s profit and free up the shelf space for other products.     

VMI环境下库存竞争性产品的补货策略及最优货架空间的确定

本文在文献[1]的研究基础上,通过深入剖析FKO模型,运用动态规划方法,探讨了呈现特殊需求性质的库存竞争性产品在VMI环境下的多期动态补货策略,以及传统库存管理中不加考虑的库存空间优化问题。本文一方面是对FKO模型的补充与扩展,同时也证实了对于在特定的VMI补货环境下采用多期库存盘查模式的供应商来说,封顶式的补货策略是最优的,并且其关于最优补货水平的多期决策都是无远见的。因此收益分享合同下的单期最优库存水平可以作为设定最优货架展示空间的依据。     

A hybrid inventory management system responding to regular demand and surge demand

This paper proposes a hybrid policy for a stochastic inventory system facing regular demand and surge demand. The combination of two different demand patterns can be observed in many areas, such as healthcare inventory and humanitarian supply chain management. The surge demand has a lower arrival rate but higher demand volume per arrival. The solution approach proposed in this paper incorporates the level crossing method and mixed integer programming technique to optimize the hybrid inventory policy with both regular orders and emergency orders. The level crossing method is applied to obtain the equilibrium distributions of inventory levels under a given policy. The model is further transformed into a mixed integer program to identify an optimal hybrid policy. A sensitivity analysis is conducted to investigate the impact of parameters on the optimal inventory policy and minimum cost. Numerical results clearly show the benefit of using the proposed hybrid inventory model. The model and solution approach could help healthcare providers or humanitarian logistics providers in managing their emergency supplies in responding to surge demands.     

How Inventory Cost Influences Introduction Timing of Product Line Extensions

In the industry with radical technology push or rapidly changing customer preference, it is firms' common wisdom to introduce high‐end product first, and follow by low‐end product‐line extensions. A key decision in this “down‐market stretch” strategy is the introduction time. High inventory cost is pervasive in such industries, but its impact has long been ignored during the presale planning stage. This study takes a first step toward filling this gap. We propose an integrated inventory (supply) and diffusion (demand) framework and analyze how inventory cost influences the introduction timing of product‐line extensions, considering substitution effect among successive generations. We show that under low inventory cost or frequent replenishment ordering policy, the optimal introduction time indeed follows the well‐known “now or never” rule. However, sequential introduction becomes optimal as the inventory holding gets more substantial or the product life cycle gets shorter. The optimal introduction timing can increase or decrease with the inventory cost depending on the marketplace setting, requiring a careful analysis.     

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。     

基于似然估计的零售商库存鲁棒均值-风险模型

针对具有风险厌恶的零售商,建立了权衡期望利润和条件风险值（CVaR）的均值-风险库存优化模型,给出了离散需求分布不确定条件下能实现帕累托最优但具有较高保守性和非帕累托最优但具有较低保守性的两种鲁棒对应。针对不确定需求分布,在仅知历史需求样本数据情况下,应用统计推断理论构建了满足一定置信水平的基于似然估计的需求概率分布不确定集。在此基础上,运用拉格朗日对偶理论,将上述两种鲁棒对应模型转化为易于求解的凹优化问题,并证明了其与原问题的等价性。最后,针对实际案例进行了数值计算,分析了不同系统参数和样本规模对零售商最优库存决策及其运作绩效的影响,并给出了零售商期望利润和条件风险值两个目标权衡的帕累托有效前沿。结果表明,采用基于似然估计的鲁棒优化方法得到的零售商库存策略具有良好鲁棒性,能够有效抑制需求分布不确定性对零售商库存绩效的影响。而且,历史需求样本规模越大,鲁棒库存策略下的零售商运作绩效越接近最优情况。进一步,通过对比发现,两种鲁棒对应模型虽然保守性不同,但在最终库存策略上保持一致。     

Pricing Decisions During Inter‐Generational Product Transition

How should companies price products during an inter‐generational transition? High uncertainty in a new product introduction often leads to extreme cases of demand and supply mismatches. Pricing is an effective tool to either prevent or alleviate these problems. We study the optimal pricing decisions in the context of a product transition in which a new‐generation product replaces an old one. We formulate the dynamic pricing problem and derive the optimal prices for both the old and new products. Our analysis sheds light on the pattern of the optimal prices for the two products during the transition and on how product replacement, along with several other dynamics including substitution, external competition, scarcity, and inventory, affect the optimal prices. We also determine the optimal initial inventory for each product and discuss a heuristic method.     

物流联合外包下库存管理模式对供应链运作的影响

针对由供应商、第三方物流服务商和零售商组成的供应链,考虑供需双方将物流服务联合外包给第三方物流服务商、共同承担运费的情形,探究供应商管理库存和寄售库存两类库存管理模式的引入对供应链运作及合同设计的影响。分别在传统的零售商管理库存、仅引入寄售库存的零售商管理寄售库存以及同时引入供应商管理库存和寄售库存的供应商管理寄售库存三种模式下,构建了第三方物流服务商主导、供应商和零售商跟随的序贯非合作博弈模型,证明了所有模式下均衡的订购量/寄售量均存在且唯一,并探讨了均衡结果随零售商运费分摊比例、转移支付价格两个关键参数的变化。横向对比三种模式下的均衡结果和集中决策下的最优结果,发现：零售商管理库存模式下的均衡订购量总是低于零售商管理寄售库存模式以及集中决策下的结果,而其他库存管理模式下的订购量并非一定低于集中决策下的结果;不同库存管理模式下,均衡状态下的订购量/寄售量及供应链总的期望收益大小关系取决于供应商和零售商的类边际(毛利)贡献率,从而表明,供应链环境下,上下游成员企业的收益结构、盈利水平等对于库存决策及库存模式的选取有重要影响。此外,在绝大多数情形下,不同库存管理模式下的均衡订购量与集中决...     

基于产品安全责任的供应链激励与竞争策略

从产品安全责任入手,基于批发价格合同,运用博弈论的基本思想,对四种情景中供应链的均衡进行分析："非竞争与非激励协调"、"非竞争与激励协调"、"竞争与非激励协调"和"竞争与激励协调"。结果显示：适度的批发价格合同激励协调措施能够提升制造商履行产品安全责任水平、市场需求量、供应链及其各成员的期望收益,但过度激励会降低市场需求量与分销商的期望收益,进而阻滞供应链总期望收益的增加;竞争将降低市场需求量、供应链及其各成员的期望收益;低度激励时竞争将降低制造商履行产品安全责任水平,高度激励时竞争将提升制造商履行产品安全责任水平;供应链采用批发价格合同激励协调机制能够增强其对外部的竞争能力,但过度竞争将降低制造商履行产品安全责任水平,进而对供应链及其各成员的利益造成损害。研究成果对供应链的产品安全责任管理实践有重要的指导意义。     

Risk-averse and risk-taking newsvendors: a conditional expected value approach

Introduction  We consider a company sourcing a product with short life cycle to stock using the framework of the newsvendor model. Traditionally, risk-neutral inventory managers are considered optimizing the expected cost or profit. But experimental findings state that the actual quantity ordered deviates from the optimal quantity derived from the classical newsvendor model. Model  Recently, the newsvendor model with objectives different from maximizing expected profit has been an active field of research. Here, we propose a newsvendor model where the inventory manager can control internal and customer-oriented performance measures. The objective function is a convex combination of conditional expected values of low and high profits, respectively. Results   We give a qualitative characterization of the optimal order quantity and the resulting performance measures in dependence of the model parameters. A risk-averse inventory manager cannot Pareto-dominate a risk-neutral or risk-taking inventory manager with respect to the expected profit and the level of product availability. Finally, the risk preferences of the inventory manager are expressed as a function of the profit value of the product with respect to the level of product availability and the probability of loss, respectively.