制造商对供方缺陷改善投资的双源采购决策研究

研究在供需均随机的情况下,面对供应原料存在质量差异的两个供应商,制造商考虑对供方进行缺陷改善投资的双源采购决策问题． 构建了制造商将高质量( 缺陷率低) 供应商作为缺陷改善低质量( 缺陷率高) 供应商的标杆,以求两供应商质量一致的双源采购决策模型． 获得了制造商在先改善投资后订货与同时改善投资和订货两种策略下最优订货量,供应商最优生产量与他们的最优利润． 分析了改善投资成功率对制造商订货量与利润的影响． 研究发现:当改善投资成功率小于1 时,先改善投资再订货时制造商利润比同时改善投资和订货时高; 而改善投资成功率为1 时,两种订货策略没有差异．     

供应风险下双源采购批发单价拍卖最优设计

考虑多个具有供应风险和成本私有信息的潜在供应商,研究了供应商投标批发单价的最优双源采购拍卖机制设计.首先,针对一般的采购商收益函数,求出了最优的订货量分配规则和供应商投标均衡,并分别与单源采购及对称信息对比,发现双源采购拍卖增加了采购商和供应商的期望利润,不对称信息对供应商有利但对采购商和供应链不利.然后,分别针对报童及垄断环境,进一步分析了双源采购拍卖下的订货分散程度、信息价值和双源采购价值,发现,订货分散程度与供应风险及两个获胜者的利润率贡献相近程度正相关;高成本获胜者比成本较低者索取更高的单位信息租金,导致不对称信息下的订货分散程度比对称信息下低;供应风险越高或投标人数越多时,双源采购价值越大.     

需求预测信息更新的零售商三阶段最优采购策略

考虑存在顾客需求预测信息更新下零售商最优订货策略,研究了三阶段订货模型,零售商首先在第一阶段订货,然后在第一阶段和第二阶段之间实现需求预测信息更新并在第二阶段调整第一阶段的订货水平,第三阶段顾客需求实现,零售商可以从实时市场购货以满足前两阶段订货不足的部分.给出了零售商的最优订货策略,通过数例说明了本文结论.     

基于采购商投资的双源采购与供应商定价决策

随着供应链的全球化发展,供应链成员企业的合作越来越紧密。许多采购商通过直接对供应商投资提高供应的可靠性或降低采购成本。本文研究双供应商-单采购商的两级供应链中采购商投资、供应商定价以及采购商采购决策。在此供应链中,供应商和采购商之间存在先后决策的Stackelberg博弈,供应商之间存在同时决策的贝特兰德博弈。本文考虑异质供应商,即供应成本与稳定性存在差异,接受采购商投资后两者的改进效应也不同,建立了采购商投资、供应商定价、采购商采购三阶段博弈模型,基于凸优化理论和博弈分析方法对问题进行分析,并应用邻域搜索的自适应差分计划算法对问题进行求解。研究了供应链成员企业的最优均衡决策,分析供应成本、供应稳定性以及投资改进效应对最优均衡决策的影响。     

基于平滑采购策略的跨国双源采购问题研究

本文研究了一个价格低但提前期长的海外供应商和一个价格高但提前期短的本地供应商同时向一个装配企业供货的双源采购问题。假设装配企业销售市场需求满足正态分布的情况下,提出了平滑采购策略,即当期采购量与上期采购量和当期市场需求量相关,以装配企业期望平均成本最低为目标,研究了装配企业摆放空间没有限制条件下双源采购量与库存的性质。然后在装配企业初始摆放空间有限,而将库存外包给第三方物流公司管理的情况下,研究了使装配企业期望平均成本最低的平滑采购系数和最优初始摆放空间。最后采用算例分析验证和求解了以上结论。研究丰富了平滑采购策略在双源采购问题中应用的相关研究,为装配企业进行国际双源采购提供了有利的参考。     

需求信息更新条件下易逝品的批量订货策略

为了获得价格折扣或运输方便,制造商常常要求零售商采取批量订货的策略.文章研究考虑顾客需求信息更新的易逝品的批量订货策略.制造商通过为零售商提供两次订货机会,来实现制造商和零售商的共赢.通过对开始时刻和顾客需求信息更新后的系统进行建模和讨论,得到了在两次订货条件下零售商应该采取的优化的订货与调整策略.     

具有两阶段生产模式和需求信息更新的供应链契约研究

针对二级供应链,在基于Stackelberg博弈的批发价契约中,分析了折扣价格与零售商最优提前订购量的关系及对契约双方期望收益的影响;设计了价格折扣与回购联合的协调契约,分析了供应链系统的最优提前生产量、供应链协调条件及协调契约下制造商和零售商的期望收益变化,并在协调契约不满足制造商的个体理性约束时,提出采用不对称Nash谈判模型设计两阶段生产与订购的回购契约,在保证供应链系统整体绩效最优的条件下,使制造商和零售商利润都能得到满意增长。研究表明,三级供应链实行两阶段订购的必要条件是分销商与零售商的最优提前订购量相等,与二级供应链相比,价格折扣契约下三级供应链效率更低,但价格折扣与回购联合的契约同样能协调三级供应链,该协调契约满足零售商与分销商激励相容约束。     

Dual Sourcing in a Serial System

We consider a finite‐horizon, periodic‐review model for a serial system with two uncapacitated external suppliers. While one external supplier (regular supplier) ships to the most upstream stage, the other one (emergency supplier) ships directly to a downstream stage. For this system, with general lead‐times we show that the optimal cost function is multimodular with respect to inventories in transit and inventories at different stages and obtain results that show how the optimal order quantities change with respect to these inventories. Our analysis also leads to sufficient conditions under which modified echelon‐basestock‐type policies are optimal.     

Dual Sourcing Inventory Systems: On Optimal Policies and the Value of Costless Returns

We study dual sourcing inventory systems with backordering and with stationary, stochastic demands. The two supply sources differ in their unit prices and lead times. We focus on the option of making costless returns to the cheaper, longer leadtime supplier. We show that the value of this option is zero. Our analysis leading to this result includes the derivation of several structural properties of the optimal policies for dual sourcing systems with and without the return option.     

Flexible Backup Supply and the Management of Lead‐Time Uncertainty

We consider replenishment decisions for a constant rate demand environment from a supplier with uncertain lead times. We study the potential use of a flexible backup supplier as an emergency response to accurate lead‐time information arriving at (or close after) the beginning of the demand interval and well after an original order with the stochastic lead‐time supplier has been placed. The emergency response decisions involve whether to order and how much from the flexible backup supplier, with the objective of minimizing the cost of meeting demand. We derive the optimal emergency‐response policy and clearly outline its implications on the optimized safety lead time of the original order placement and on the cost of meeting demand. We examine the impact on the use of the flexible backup supplier of factors like the arrival time of accurate lead‐time information and the response lead time of the backup supplier. We further study the potential benefits of the use of the flexible backup supplier in a dual role: as one of the two suppliers in a redundant supply system assigned to originally meet the demand and as an emergency response to later‐arriving lead‐time information. Our numerical studies illustrate the benefits from the use of the flexible backup supplier as an emergency response, but for reasonable purchase premiums and short lead times of flexible backup supply options, their use in a dual (regular and emergency response) role often leads to improved performance over safety lead‐time single and uncertain lead‐time supplier‐replenishment strategies. The benefits of the backup supply options are accentuated the higher the lead‐time uncertainty of the stochastic lead‐time supplier is.     

Optimal Inventory Control with Dual‐Sourcing,Heterogeneous Ordering Costs and Order Size Constraints

We consider a dual‐sourcing inventory system, where procuring from one supplier involves a high variable cost but negligible fixed cost whereas procuring from the other supplier involves a low variable cost but high fixed cost, as well as an order size constraint. We show that the problem can be reduced to an equivalent single‐sourcing problem. However, the corresponding ordering cost is neither concave nor convex. Using the notion of quasi‐convexity, we partially characterize the structure of the optimal policy and show that it can be specified by multiple thresholds which determine when to order from each supplier and how much. In contrast to previous research, which does not consider order size constraints, we show that it is optimal to simultaneously source from both suppliers when the beginning inventory level is sufficiently low. We also show that the decision to source from the low‐cost supplier is not monotonic in the inventory level. Our results require that the variable costs satisfy a certain condition which guarantees quasi‐convexity. However, extensive numerical results suggest that our policy is almost always optimal when the condition is not satisfied. We also show how the results can be extended to systems with multiple capacitated suppliers.     

Strategic Sourcing in the Presence of Uncertain Supply and Retail Competition

This study develops an analytical model to evaluate competing retail firms' sourcing strategies in the presence of supply uncertainty. We consider a common supplier that sells its uncertain supply to two downstream retail firms engaging in price competition in a horizontally differentiated product market. The focal firm has a dual‐sourcing option, while the rival firm can only source from the common supplier. We assess the system‐wide effects of supply uncertainty on the focal firm's incentive to pursue the dual‐sourcing strategy. We find that the focal firm's dual‐sourcing strategy can create a win–win situation that leads to increased retail prices and expected profits for both firms. Furthermore, under certain conditions, we show that it is beneficial for the focal firm to strategically source from the common supplier, even if its alternative supplier offers a lower wholesale price. Overall, we identify two types of incentives for adopting the dual‐sourcing strategy: the incentive of mitigating supply risk through supplier diversification and the incentive of strategic sourcing for more effective retail competition.     

Dual Sourcing Under Random Supply Capacities: The Role of the Slow Supplier

Sourcing from multiple suppliers with different characteristics is common in practice for various reasons. This paper studies a dynamic procurement planning problem in which the firm can replenish inventory from a fast and a slow supplier, both with uncertain capacities. The optimal policy is characterized by two reorder points, one for each supplier. Whenever the pre‐order inventory level is below the reorder point, a replenishment order is issued to the corresponding supplier. Interestingly, the reorder point for the slow supplier can be higher than that of the fast even if the former has a higher cost, lower reliability, and smaller capacity than the latter, suggesting the possibility of ordering exclusively from an inferior slow supplier in the short term. Moreover, the firm may allocate a larger portion of the long‐term total order quantity to the slow supplier than to the fast, even if the former does not possess any cost or reliability advantage over the latter. Such phenomena, different from the observations made in previous studies, happen when the demand is uncertain and the supply is limited or unreliable. Our observations highlight the importance of incorporating both demand uncertainty and supplier characteristics (i.e., cost, lead time, capacity and uncertainty) in a unified framework when formulating supplier selection and order allocation strategies.     

Supply Disruptions,Heterogeneous Beliefs,and Production Efficiencies

Recent years have witnessed the pervasive supply disruptions and their impacts on supply chain performance. In this study, we investigate the optimal procurement design with supply disruptions and heterogeneous beliefs between the buyer and the supplier. We examine the impact of information asymmetry on the supplier's belief, the control right of the backup production, and the verifiability of supply disruption. The belief heterogeneity creates speculative gains and losses because the buyer and the supplier hold different estimates of the disruption probability. We demonstrate that the buyer's incentive to exploit this belief heterogeneity leads to real production inefficiencies in different scenarios. The production efficiency is not necessarily improved with more transparent information. Moreover, a very pessimistic supplier may have no incentive to invest in improving the reliability even if this is costless, and the supplier may produce more when the expected production cost becomes higher. When the buyer sees some value in using the supplier's estimate to update his own belief, we find that the main results hold unless the buyer completely abandons his belief.     

The Impact of Information Sharing and Advance Order Information on a Supply Chain with Balanced Ordering

This paper considers a supply chain with one supplier and multiple retailers that face exogenous heterogeneous end‐customer demands, where all parties utilize base‐stock policies. Each retailer is restricted to order once in every order cycle and their orders are replenished in a balanced manner within the cycle. Our study investigates the impact of information sharing and advance order information (AOI) on the supply chain. We find that the supplier benefits from the two mechanisms via two important factors, the information about observed end‐customer demands and the decision on re‐establishing the replenishment sequence. We derive the supplier's optimal sequence for stochastically comparable end‐customer demands with AOI and propose a sequencing rule for the setting with information sharing. Our numerical study examines the cost impacts of two proposed mechanisms on the entire supply chain.