两类供应风险下装配商的最优订购策略

针对两类供应风险(不确定产能与随机产出率)下装配制造商的零部件订购决策这一难题,运用随机非线性规划方法,以装配商期望利润最大化为目标,建立零部件订购决策的多维优化模型,刻画了确定需求下的最优订购量,并对其进行了灵敏性分析。最后,通过数值算例验证了模型结论并进一步探讨不同类供应风险的影响,为装配商的零部件订购决策和风险管理提供有益的管理启示。     

Coordination of stocking decisions in an assemble-to-order environment

This paper examines an assemble-to-order environment involving a short-life-cycle product that is sold in two different configurations, each requiring a unique component that must be stocked in advance. Both configurations of the product are assembled on the same equipment which has limited capacity. The focus of the analysis is on the determination of the appropriate stocking quantities for each of the configuration specific components. Because the same assembly capacity is often reused for different instances of the component stocking problem, we treat assembly capacity as exogenous. This represents the fact that capacity decisions are often made less frequently than are procurement/production quantity decisions. We first solve for the first-best stocking policy when the components are produced internally. We then consider the case when the components are procured from external suppliers, and investigate how different forms of contract between the assembler and the component suppliers affect coordination of the supply chain as well as each party’s profit. One particularly interesting finding is that it is possible to coordinate the supply chain with a single-price contract between each supplier and the assembler while awarding all parties positive profit.     

供应商风险规避情形下基于期权契约的组装供应链协调

基于产品分工的发展及供应链成员风险偏好不同的特性,构建了由多个风险规避的零部件供应商和一个组装商构成的两阶段组装供应链模型.首先,发现在各供应商均采用批发价格契约向组装商提供零部件情况下,各供应商的最优产量均小于集中决策下的最优产量;其次,引入期权契约机制对组装供应链进行了协调;最后,通过数值算例验证了期权契约协调机制的有效性.     

Impact of equity and equality on stability and collusion in a decentralized network

We consider a firm that procures a product from a regular supplier whose production is subject to both supply disruption and random yield risks and a backup supplier whose production capacity requires reservation in advance. Under both deterministic and stochastic demand, we study the impact of the two types of supply risks on the firm’s optimal procurement decisions and the importance of correctly identifying the source of supply risks. We find that if the overall supply risk is unchanged but its main source shifts from random yield to supply disruption, the firm should order more from the regular supplier and reserve less capacity from the backup supplier. Ignoring the existence of supply disruption leads to under-utilization of the regular supplier and over-utilization of the backup supplier. Moreover, we examine the option value of the reserved capacity that is affected by the uncertainty of customer demand. We find that the option value increases/decreases in demand uncertainty if the reservation capacity is exercised after/before demand is realized.     

Integrated inventory management and supplier base reduction in a supply chain with multiple uncertainties

This paper considers a manufacturing supply chain with multiple suppliers in the presence of multiple uncertainties such as uncertain material supplies, stochastic production times, and random customer demands. The system is subject to supply and production capacity constraints. We formulate the integrated inventory management policy for raw material procurement and production control using the stochastic dynamic programming approach. We then investigate the supplier base reduction strategies and the supplier differentiation issue under the integrated inventory management policy. The qualitative relationships between the supplier base size, the supplier capabilities and the total expected cost are established. Insights into differentiating the procurement decisions to different suppliers are provided. The model further enables us to quantitatively achieve the trade-off between the supplier base reduction and the supplier capability improvement, and quantify the supplier differentiation in terms of procurement decisions. Numerical examples are given to illustrate the results.     

Random yield supply chain with a yield dependent secondary market

This paper considers a simple supply chain with one supplier and one retailer where the supplier’s production is subject to random yield and the retailer faces uncertain demand. There exists a secondary market for acquiring or disposing products by the supplier. We study both the centralized and decentralized systems. In the decentralized system, a no risk sharing contract and a risk sharing minimum commitment contract are analyzed. The supply chain with the risk sharing contract is further analyzed with a constant secondary market price and a yield dependent secondary market price. We present both the supplier’s and the retailer’s optimal strategies and provide insights for managers when making decisions under random yield risk and demand uncertainty. We find that the secondary market generally has a positive impact on supply chain performance and the actual effect of random yield risk on the supply chain performance depends on cost parameters and supply chain contract settings. Under certain conditions, reducing yield randomness may weaken the double marginalization effect and improve the chain performance. From the numerical study, we also show that there exists an optimal commitment level for the supply chain.     

装配系统中的供应商融资:银行贷款vs买方预付款

由多个供应商和一个装配商组成的装配系统中,装配商组装的最终产品需要由供应商提供零部件,不同供应商提供的零部件是互补的。供应商与装配商之间采用批发价格合同,由供应商决定批发价格而装配商决定订货量。供应商的资金是有限的,可能影响其供货能力以及装配系统的效率。供应商可以向银行借款或者由下游装配商提供预付款以缓解其资金约束的不利影响。针对银行贷款的情形,分析了装配系统的均衡订货量与批发价格,并通过图示直观地描述了资金约束对均衡订货量的影响。在装配商提供预付款时,若预付比例为外生变量,则供应商之间的博弈存在存策略纳什均衡,装配系统的绩效与预付比例以及供应商的资金有关;若预付比例是供应商的决策变量,则预付款可有效解决供应商的资金约束,相比于银行贷款,预付款的融资模式可使装配商和装配系统取得更高的利润。     

Price markdown scheme in a multi-echelon supply chain in a high-tech industry

This paper studies the price markdown scheme in a supply chain that consists of a supplier, a contract manufacturer (CM), and a buyer (retailer). The buyer subcontracts the production of the final product to the CM. The CM buys the components from the supplier and charges the buyer a service fee for the final product produced. The price markdown is made possible by the supplier with the development of new manufacturing technologies that reduce the production cost for the sourced component. Consequently, the buyer adjusts the retail price in order to possibly stimulate stronger demand that may benefit both the supplier and the buyer. Under this scenario, we identify the optimal discount pricing strategies, capacity reservation, and the stocking policies for the supplier and the buyer. We also investigate the optimal inventory decision for the CM to cope with the price discount by considering both demand and delivery uncertainties. Our results suggest that higher production cost accelerates the effects of higher price sensitivity on lowering the optimal capacity and stocking policies in the supply chain. The effect of mean demand error on the optimal prices is relatively marginal compared with that from price sensitivity. We also found that increasing the standard deviation of the random demand does not necessarily increase the stocking level as one would predict. The results show that delivery uncertainty plays an important role in the inventory carried beyond the price break. We discuss potential extensions for future research.     

Coordination in decentralized assembly systems with uncertain component yields

The literature on assembly systems with random component yields has focused on centralized systems, where a single decision maker chooses all components’ production quantities and incurs all the costs. We consider a decentralized setting where the component suppliers choose their production quantities based solely on their own cost/reward structure, and the assembly firm makes ordering decisions based on its own cost/reward structure. When the suppliers control their inputs but the outputs exhibit random yields, coordination in such systems becomes quite complex. In such situations, incentive alignment control mechanisms are needed so that the suppliers will choose production quantities as in the centralized system case. One such mechanism is to penalize the supplier with the worse delivery performance. We analyze the conditions under which system coordination is achieved while respecting participation constraints. Further, we determine the optimal component ordering policy for the assembly firm and derive the optimal coordinating penalties.     

Exploiting timely demand information to reduce inventories

Electronic Data Interchange (EDI) and related technologies are making it less expensive to frequently transmit demand information up the supply chain from the point of sale. However, little is known about how the various participants in the supply chain might exploit more timely demand information. This research is intended to be an opening contribution to the analytical study of timely demand information. We study a simple two-level system composed of a supplier (or component plant) and a single customer (or final assembly plant). The two factories use a standard periodic base-stock policy for one particular item, but the equal-length production cycles of the two factories do not necessarily coincide. Both participants hold inventories to buffer the effects of uncertain orders and uncertain deliveries. The supplier is in turn supplied by a source with infinite capacity. Final demand occurs only at the final assembly plant, which communicates demand over its order cycle to the component plant. If the component plant begins a production cycle between orders from the final assembly plant, it is uninformed about some number of days' demand which has been observed at the customer but not yet communicated. Any technology, such as EDI, that makes it cheaper for the customer to communicate demand as it occurs allows the supplier to base its decisions on more accurate information. With more accurate demand information the supplier could reduce inventories, or improve the reliability of its deliveries to its customer, or both. The customer, in turn, could reduce its inventories if its supplier were more reliable. We examine the changes brought about by the exchange of timely demand information in inventories and service levels at both the supplier and customer. Our results show that inventory-related benefits are particularly sensitive to demand variability, the service level provided by the supplier, and the degree to which the order and production cycles are out of phase.     

随机需求下基于供应中断的备份供应商决策分析

假定需求服从随机分布,研究由零售商主导的供应链中,采用一个战略供应商和一个备份供应商模式,零售商与备份供应商通过能力期权建立订货契约:首先,零售商向备份供应商预订能力,支付预订成本;接着,向战略供应商订货,如果没有发生突发事件则其供货量等于订货量,否则供货量变为零;然后,零售商基于战略供应商的供货量和备份供应商的能力预订确定向备份供应商的订货量,支付执行成本;最后,零售商用战略供应商和备份供应商的总供货量满足顾客需求。备份供应商在考虑自己的能力维持成本和制造成本后决定是否接受零售商提供的能力期权契约。针对零售商可选择的四种不同策略,求得采取不用策略所满足的条件,并给出相应的最优订货量、能力预订量和能力执行量和最优利润等的解析解。     

The impact of decision timing on the suppliers’ interactions: simultaneous moves <Emphasis Type="Italic">versus</Emphasis> sequential moves

The last few decades have witnessed a huge growth of outsourcing in industry where the downstream firm assigns its production tasks to different upstream suppliers. This makes the supply chain structure more complicated and gives rise to some relevant operational questions. This paper focuses on a supply chain structure that consists of one assembler and two suppliers, and both suppliers’ production yields are stochastic. The assembler delegates the quantity decisions to the suppliers, and the two suppliers choose their production quantities either simultaneously or sequentially. We compare the suppliers’ equilibrium production strategies under these two scenarios. Our results show that the decision sequence can exert significant influences on the firm’s and channel’s equilibrium payoffs. At any given wholesale price, both suppliers produce more components under sequential moves than under simultaneous moves, and this results in higher payoffs for the suppliers, the assembler and the entire supply chain. The supplier’s profit increases if he can make the decision later under sequential moves. From the channel’s perspective, it is more beneficial for the supplier with a higher production cost to make the decision first. The assembler is able to extract more surplus by endogenously setting the wholesale price. However, this may make the suppliers worse off under sequential moves than under simultaneous moves.     

随机产出下考虑小微供应商成本利润率的供应链决策研究

小微型供应商由于产能、资金等限制,其目标可能是实现成本利润率最优,从而提高企业生存能力。基于该观察,区别于多数文献采用利润最优决策准则,本文研究由小微供应商和零售商组成的单周期供应链决策问题。小微供应商面临产出随机风险,以成本利润率最大为目标进行产能决策,零售商以利润最大为目标确定最优订购量。研究发现小微供应商的成本利润率受到自身成本偏重系数以及零售商盈利能力的共同影响,将出现亏损、合理盈利、超额盈利三种情况。并且,零售商采取不同订货策略也会对小微供应商盈利情况产生差异影响。保守(积极)订货策略下,零售商是否盈利取决于自身单位净利润能否弥补单位缺货损失(自身可盈利空间)。本文研究融合现实普遍存在的产出随机问题,为小微供应商和其他供应链成员的产能/订购决策问题提供有益的管理启示。     

产能限制下单向替代产品供应链生产、订货与定价研究

考虑一个产能受限的制造商和一个零售商组成的二级供应链上供需双方信息不完全对称的情景,研究具有单向替代的两种产品生产、订货及响应性定价的供应链决策问题,把问题建立成一个三阶段博弈模型。理论分析得出不同条件下制造商的最优产量及零售商的最优订货和定价决策。通过算例验证了供应链上的最优决策及其条件,灵敏度分析表明制造商产能、潜在市场需求及其方差、替代品的价格敏感系数在一定范围内增大有利于供应链系统及各成员利润增加,被替代产品的价格敏感系数增大可能会导致供应链及制造商利润下降。     

Coordinated decisions for substitutable products in a common retailer supply chain

This paper studies coordination mechanisms in a supply chain which consists of two suppliers with capacity uncertainties selling differential yet substitutable products through a common retailer who faces price-sensitive random demand of these two products. We develop in a noncompetitive setting three coordination models – revenue sharing, return policy, and combination of revenue sharing and return policy – and contrast them with a basic and uncoordinated model. We are able to establish the ordinal relationship among the retailer’s ordering and pricing decisions and analytically compare the performances between certain models when two suppliers are identical. We find that the retailer’s ordering and pricing decisions in the model with return policy in the case of identical suppliers are independent of demand or supply uncertainty. Our numerical results reveal that the performances of coordination models in the case of nonidentical suppliers resemble those in the case of identical suppliers. We find that the retailer will place a larger order quantity in models where her average cost per unit sold is smaller. We also find that product substitutability and uncertainties have different effects on chain performances.     

A note on coordination in decentralized assembly systems with uncertain component yields

Gurnani and Gerchak [H. Gurnani, Y. Gerchak, Coordination in decentralized assembly systems with uncertain component yields, European Journal of Operational Research 176 (2007) 1559–1576] study coordination of a decentralized assembly system in which the demand of the assembler is deterministic and the component yields are random. They present incentive alignment control mechanisms under which system coordination is achieved. In this note, we extend Gurnani and Gerchak’s model to the case of positive salvage value and n asymmetric suppliers, and show that the shortage penalty contract which can coordinate Gurnani and Gerchak’s model no longer coordinates the extended model. Furthermore, we present a new kind of contract, surplus subsidy contract, to coordinate the extended model and prove that the profit of the supply chain under coordination can be arbitrarily divided between the component suppliers and the assembler.     

基于供应方生产能力的应急物资生产模型

利用期权契约所建立的政企合作储备应急物资模式能够有效解决政府单独储备模式所造成的物资储备量过少或过多而引起的困境。然而由于应急物资的需求特性,若应急物资供应企业采用按单生产方式安排生产储备计划,势必会造成库存水平升高,引发资金周转困难等问题,对政企之间的长期合作造成不利影响。基于此,本文设计了基于供应方生产能力的应急物资生产模型。该模型在政府利用批发价格契约与期权契约采购应急物资的基础上,研究了供应方根据自身生产能力进行柔性生产时的生产与储备问题。通过推导政企双方最优决策后,重点分析了期权权利金,执行价格,加急生产成本等参数对供应方生产决策的影响,并证明与按单生产模式相比,柔性生产模式可有效降低供应方的库存量与生产成本,提高其利润,继而提高整体供应链的利润水平,有助于促进政企之间长期稳定的合作。     

考虑即时采购价格的物流服务供应链优化

物流服务市场的不确定性会影响物流服务供应链的服务水平和收益。在考虑随机即时采购价格以及基础物流提供商在正常情况和应急情况下具有不同物流能力投资成本的情形下,引入期权机制研究不确定市场环境下物流服务供应链的优化决策,以提高物流服务供应链柔性和降低市场不确定性带来的风险。构建物流服务供应链的期权契约模型,采用Stackelberg博弈理论和优化算法分析和求得物流服务集成商的最优期权采购和即时采购策略,以及基础物流提供商的最优物流能力投资策略。结果表明即时采购价格将影响基础物流提供商和物流服务集成商的决策。最后通过数值分析研究即时采购价格的不确定程度对物流服务集成商和提供商的优化策略和利润的影响。     

供应链中的生产能力投资风险分配

在供应链中,每个管理者都会面临各种各样的供应和需求不确定性.这些不确定性会造成生产能力的过剩或不足,从而导致很大的利益损失,但是未必每个公司都会面临生产能力投资风险.针对一个单生产商单零售商系统,本文分析了三种不同的合同设计（推进式批发价合同,拉动式批发价合同和期权合同）对生产商和零售商的利润和生产能力投资风险的影响,推进式批发价合同和拉动式批发价均不能协调供应链,故我们找到其帕累托集;而对于期权合同,它能够协调整个供应链并且整合推进式和拉动式两种批发价合同使得生产商和零售商共同承担生产能力投资风险.在分析的过程中,我们将结果与已有的结果进行了比较,指出了其异同之处.     

Single versus multiple supplier sourcing strategies

Successful supply chain management necessitates an effective sourcing strategy to combat uncertainties in both supply and demand. In particular, supply disruption results in excessive downtime of production resources, upstream and downstream supply chain repercussions, and eventually a loss in the market value of the firm. In this paper we analyze single period, single product sourcing decisions under demand uncertainty. Our approach integrates product prices, supplier costs, supplier capacities, historical supplier reliabilities and firm specific inventory costs. A unique feature of our approach is the integration of a firm specific supplier diversification function. We also extend our analysis to examine the impact of minimum supplier order quantities. Our results indicate that single sourcing is a dominant strategy only when supplier capacities are large relative to the product demand and when the firm does not obtain diversification benefits. In other cases, we find that multiple sourcing is an optimal sourcing strategy. We also characterize a non-intuitive trade-off between supplier minimum order quantities, costs, and supplier reliabilities. Finally, we examine the robustness of our results through an extensive numerical analysis of the key parameters of our model.