不确定需求下考虑供应商参与机制的应急资源配置鲁棒优化研究

突发事件应急资源优化配置是突发事件发生后救援工作有效开展的前提和基本保障。本文在调研国内外相关研究的基础上，以应对地震灾难为背景研究考虑供应商参与机制的应急资源保障策略，在灾前选择供应商建立政府与供应商的合作机制完成政府储备仓库的选址与资源配置，突发事件发生后依托政府储备仓库和供应商生产能力共同满足应急救援对应急资源的分时段需求，以期协调供应商与政府储备、灾前实物采购与灾后生产能力采购的比例，在保障救援效率的同时降低应急资源保障体系的成本。同时由于地震灾难发生具有需求不确定性的特点，本文引入L1范数描述需求的不确定性，建立了备灾与灾害救援两阶段决策的鲁棒优化模型，并给出了鲁棒模型对应问题的转化方法。最后通过算例仿真验证了模型和对应问题转换方法的有效性，为地震的应对提供理论指导和决策支持。     

考虑供应风险的多源应急物资采购双层规划模型

自然灾害频繁发生,事故灾难不断涌现,公共卫生事件猝不及防,社会安全风险交织叠加,给人们的生产和生活带来了巨大的风险和不确定性。在突发事件背景下,考虑应急物资供应中的各类风险,激励多源应急物资的稳定供给,受到党和政府高度重视。应急物资供应有哪些风险,如何规避这些风险,针对多种渠道的采购,如何优化采购结构。这些问题是本论文关注的重点。本文以政府、制造型企业、受灾地区民众为决策主体的三级供应链为基础,构建了上层以整个供应链系统收益最大化为目标函数、下层以供应风险最小化为目标函数的双层规划模型,对不同情景下物资采购订单的分配进行研究。在此基础上,本文以某市洪涝灾害为例进行分析,证明了模型的可行性,并探究了供应风险变化对物资采购订单分配、以及整个供应链系统收益的影响,以期为政府应急物资采购决策提供参考性建议。     

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.     

Push or Pull? Auctioning Supply Contracts

Consider a buyer, facing uncertain demand, who sources from multiple suppliers via online procurement auctions (open descending price‐only auctions). The suppliers have heterogeneous production costs, which are private information, and the winning supplier has to invest in production capacity before the demand uncertainty is resolved. The buyer chooses to offer a push or pull contract, for which the single price and winning supplier are determined via the auction. We show that, with a pull contract, the buyer does not necessarily benefit from a larger number of suppliers participating in the auction, due to the negative effect of supplier competition on the incentive of supplier capacity investment. We thus propose an enhanced pull mechanism that mitigates this effect with a floor price. We then analyze and compare the outcomes of auctions for push and (enhanced) pull contracts, establishing when one form is preferred over the other based on the buyer's profits. We also compare our simple, price‐only push and pull contract auctions to the optimal mechanisms, benchmarking the performance of the simple mechanisms as well as establishing the relative importance of auction design and contract design in procurement auctions.     

SHORT‐TERM E‐PROCUREMENT STRATEGIES VERSUS LONG‐TERM CONTRACTS

In this paper we compare the following procurement strategies based on their expected costs: strategic partnership, which is based on a long‐term relationship with a single supplier; online search, which is a short‐term strategy; and a combined strategy, which is some combination of the first two strategies. In addition, we determine for the online search and combined strategy the optimal number of suppliers to contact for a price quote, and analyze how it depends on the various cost and demand parameters. The main contribution of this paper is that it does not assume a single procurement strategy, but rather compares three alternatives.     

基于期权契约的政企联合储备应急物资模型与利润分配机制研究

突发灾害发生后，应急物资需求量呈现爆发式增长。在实际情况下，为了保障应急物资的及时性与可用性，政府可能与不止一家供应商联合储备应急物资。目前众多研究均假设在应急物资供应链中，只存在一个应急物资供应商，鲜有关于政府与多个供应商联合储备应急物资的研究，也缺少对竞争型供应商利润分配机制的探讨。当然，与政府达成储备合作协议的企业也不宜过多，否则会增加政府对供应商利润分配的难度及潜在的管理成本。因此，本研究以政府与两个竞争型供应商联合储备应急物资的情形为例，构建了基于期权契约的政府与两个供应商联合储备应急物资模型，推导出政企最优决策策略。当供应链达到协调时，与政府单独储备模型相比，政企联合储备应急物资模型降低了政府常规物资储备水平，提高了应急物资储备总量。在此基础上，本文还给出了政府成本与两个供应商利润都得到改善的条件，确定了合理分配供应商利润的期权执行价格取值范围。本研究更加贴近我国国情与应急物资储备的实际情况及现实条件，对强化政企合作储备应急物资具有重要的意义，为政府更好地应对突发灾情提供了操作策略与指导原则。     

On E‐Auctions for Procurement Operations

Electronic auctions have revolutionized procurement in the last decade. In many situations, they have replaced negotiations for supplier selection and price setting. While they have often greatly reduced transaction costs and increased competition, they have also encountered problems and resistance from suppliers resenting their intrusion on cooperative supplier/buyer relationships. In response to these issues, procurement auctions have evolved in radical new directions. Buyers use business rules to limit adverse changes. Some procurement auctions allow bidders to offer variants in the specifications of products to be supplied. Most important, some suppliers are allowing bidders to bid on packages of items, not just individual items. This tends to change procurement auctions from zero‐sum fights over supplier profit margins to win‐win searches for synergies. These changes have opened up many new research areas. Researchers are trying to improve how to deal with the computational issues involved in package auctions and to analyze the new auctions forms that are evolving. In general, equilibrium incentives are not known, and dealing with ties in package auctions is an issue. Computer scientists are analyzing the use of computerized bidding agents. Mechanisms that combine auctions with fixed buy prices or with negotiations need to be analyzed.     

The supplier selection problem with quantity discounts and truckload shipping

To minimize procurement expenditures both purchasing and transportation costs need to be considered. We study a procurement setting in which a company needs to purchase a number of products from a set of suppliers to satisfy customer demand. The suppliers offer total quantity discounts and transportation costs are based on truckload shipping rates. The goal is to select a set of suppliers so as to satisfy product demand at minimal total costs. The resulting optimization problem is strongly NP-hard. We develop integer programming based heuristics to solve the problem. Extensive computational experiments demonstrate the efficacy of the proposed heuristics and provide insight into the impact of instance characteristics on effective procurement strategies.     

Failure Risk and Quality Cost Management in Single versus Multiple Sourcing Decision

The advantage of multiple sourcing to protect against supplier failures arising from undependable products due to latent defects is examined using a model with nonlinear external failure costs. Prior research has focused only on supplier failures arising from unreliable supply, such as late, insufficient, or no delivery. I derive a closed‐form characterization of the optimal production quota allocation for the LUX (Latent defect‐Undependable product‐eXternal failure) setting. The allocation determines the optimal supply base, with intuitive properties that hold under a mild requirement. The requirement includes the special case of equal procurement costs charged by suppliers but also allows unequal costs without any particular order. The key result of the article is a necessary and sufficient condition determining whether single or multiple sourcing is optimal. Another condition is obtained to determine the exact size of the optimal supply base, provided the mild requirement holds. With minor modifications, the results also hold when a buyer‐initiated procurement contract can be used to elicit private information on the suppliers’ unit variable production costs.     

基于数量柔性契约的双源应急物资采购定价模型

针对灾害事件发生的不确定性以及灾害发生后应急物资需求量的爆发式增长，本文设计了一个政府主导的基于数量柔性契约的双源应急物资采购模型。在存在一个现货市场的情况下，政府除了常规采购外，还会与供应方签订一份数量柔性契约，用以建立政企联合储备应急物资的合作关系。通过数理推导，本文发现灾害事件发生概率，政府自身储备量，现货市场采购价格会对双方决策产生重要影响，并给出三个影响因素在满足不同条件时政企双方的最优决策，同时进一步分析了这三个因素对政府采购成本与供应方利润的影响。最后，通过数值模拟的方式对所得结论进行了验证。本文的研究为政府与企业构建联合储备应急物资的合作关系提供了指导与依据。     

Optimal Descending Mechanisms for Constrained Procurement

Descending mechanisms for procurement (or, ascending mechanisms for selling) have been well‐recognized for their simplicity from the viewpoint of bidders—they require less bidder sophistication as compared to sealed‐bid mechanisms. In this study, we consider procurement under each of two types of constraints: (1) Individual/Group Capacities: limitations on the amounts that can be sourced from individual and/or subsets of suppliers, and (2) Business Rules: lower and upper bounds on the number of suppliers to source from, and on the amount that can be sourced from any single supplier. We analyze two procurement problems, one that incorporates individual/group capacities and another that incorporates business rules. In each problem, we consider a buyer who wants to procure a fixed quantity of a product from a set of suppliers, where each supplier is endowed with a privately known constant marginal cost. The buyer's objective is to minimize her total expected procurement cost. For both problems, we present descending auction mechanisms that are optimal mechanisms. We then show that these two problems belong to a larger class of mechanism design problems with constraints specified by polymatroids, for which we prove that optimal mechanisms can be implemented as descending mechanisms.     

An integrated supplier selection and inventory problem with multi-sourcing and lateral transshipments

In this research, we consider the supplier selection problem of a firm offering a single product via multiple warehouses. The warehouses face stationary, stochastic demand and replenish their inventory via multiple suppliers, to be determined from a set of candidates, with varying price, capacity, quality, and disruption characteristics. Additionally, the warehouses may simultaneously replenish their inventory from other warehouses proactively. With these characteristics, the problem is a multi-sourcing, supplier selection, and inventory problem with lateral transshipments. Even though the benefits of multi-sourcing and lateral transshipments have been presented in the literature individually to mitigate risks associated with uncertain demand and disrupted supply, the intertwined sourcing and inventory decisions under these settings have not been investigated from a quantitative perspective. We develop a decomposition based heuristic algorithm, powered with simulation. While the decomposition based heuristic determines a solution with supplier selection and inventory decisions, the simulation model evaluates the objective function value corresponding to each generated solution. Experimental results show, contrary to the existing literature, inferior decisions may result when considering the selection of suppliers solely on unit and/or contractual costs. We also evaluate the impact of multi-sourcing with rare but long disruptions compared to frequent but short ones.     

Carrots or Sticks? Improving Social and Environmental Compliance at Suppliers Through Incentives and Penalties

Firms are increasingly looking to eradicate social and environmental non‐compliances at their suppliers in response to increasing regulations, consumer demand, potential for supply chain disruptions, and to improve their social, environmental, and economic supply chain performance. This study develops a model of the relationship between the buyer's supplier incentives and penalties for the supplier's social and environmental compliance, and the outcomes in terms of reduction in supplier social and environmental violations as well as the buyer's own operating costs. This model is tested empirically through analysis of a dataset of opinion‐based survey responses from practitioners at 334 companies across 17 industries. The analysis finds specific penalties and incentives that are positively associated with reduced supplier violations and reduced buyer operating costs. In particular, offering suppliers incentives of increased business and training for improving social and environmental performance is strongly associated with a reduction in both violations and operating costs.     

“Do as I Do and Not as I Say”: Exploring Price‐Oriented Maverick Buying During Supplier Selection

This article empirically examines the occurrence of price‐oriented maverick buying (MB) during supplier selection, in a direct purchasing process context. Drawing on agency theory, maverick buying, and total cost of ownership (TCO) literature, the statistically significant existence of price‐oriented MB is investigated and the purchasing manager (PM)‐related factors that influence such noncompliant behavior are determined. A discrete choice experiment is designed to simulate a TCO‐based supplier selection process in which an established purchasing framework agreement stipulates PMs not necessarily be price‐oriented (i.e., select suppliers primarily based on lowest price), and then models PM choice behavior in the supplier selection process (SSP), utilizing a conditional logit model (CLM) to determine PM compliance to the established purchasing framework agreement and identify if price‐oriented MB exists. Statistical tests utilizing comprehensive primary and secondary data are then conducted to determine if correlational relationships exist between PM‐related factors and PM price‐orientation. Results indicate that three PM‐related factors bear a significant correlational relationship to PM price‐orientation.     

多部件采购外包的两阶段均衡投标策略

本文考虑一个由单个制造商和多个供应商群体组成的供应链——该制造商需要采购多个部件,对于每个部件在市场上均存在多个供应商。不同于传统的从各供应商群体分别采购各个部件,制造商考虑将所有部件的采购整体外包给某个供应商。在第一阶段,制造商使用一级价格密封投标的逆向拍卖来确定赢得整体采购合约的供应商。接下来,第一阶段投标的获胜者生产其所能供应的部件,并使用逆向拍卖向第一阶段中未获胜的其他竞标者采购其余部件。我们分析了供应商在两个阶段的均衡竞价策略,并比较了制造商在亲自逐件采购和外包整体采购两种情况下的期望采购成本。我们证明了在两种机制下制造商的总的期望采购成本相等。     

Managing Disruptions in Decentralized Supply Chains with Endogenous Supply Process Reliability

Supply disruptions are all too common in supply chains. To mitigate delivery risk, buyers may either source from multiple suppliers or offer incentives to their preferred supplier to improve its process reliability. These incentives can be either direct (investment subsidy) or indirect (inflated order quantity). In this study, we present a series of models to highlight buyers’ and suppliers’ optimal parameter choices. Our base‐case model has deterministic buyer demand and two possibilities for the supplier yield outcomes: all‐or‐nothing supply or partial disruption. For the all‐or‐nothing model, we show that the buyer prefers to only use the subsidy option, which obviates the need to inflate order quantity. However, in the partial disruption model, both incentives—subsidy and order inflation—may be used at the same time. Although single sourcing provides greater indirect incentive to the selected supplier because that avoids order splitting, we show that the buyer may prefer the diversification strategy under certain circumstances. We also quantify the amount by which the wholesale price needs to be discounted (if at all) to ensure that dual sourcing strategy dominates sole sourcing. Finally, we extend the model to the case of stochastic demand. Structural properties of ordering/subsidy decisions are derived for the all‐or‐nothing model, and in contrast to the deterministic demand case, we establish that the buyer may increase use of subsidy and order quantity at the same time.     

供应商产出随机与供应中断下的双源采购决策

研究在需求与供应不确定条件下，一个制造商向两个存在产出随机和供应中断可能性的供应商采购零部件时的最优决策问题。论文分别针对两种情况：（1）只考虑供应商产出随机，（2）同时考虑供应商产出随机与供应中断可能性，建立了两种情况下制造商与两个供应商之间的博弈模型，证明了在两种情况下，制造商均存在最优订货量、供应商存在最优生产量使自身利润最优。研究发现，供应商产出稳定性的改善（即产出随机性降低）不仅可以使自身获得更大的利润，也使制造商获得更大的利润。供应商最优生产量随着自身产出随机性降低先增后减。同时，供应商供应中断可能性的降低会为自身带来更大的收益，也为制造商带来更大的收益。     

Organizing the Global Value Chain

We develop a property‐rights model of the firm in which production entails a continuum of uniquely sequenced stages. In each stage, a final‐good producer contracts with a distinct supplier for the procurement of a customized stage‐specific component. Our model yields a sharp characterization for the optimal allocation of ownership rights along the value chain. We show that the incentive to integrate suppliers varies systematically with the relative position (upstream versus downstream) at which the supplier enters the production line. Furthermore, the nature of the relationship between integration and “downstreamness” depends crucially on the elasticity of demand faced by the final‐good producer. Our model readily accommodates various sources of asymmetry across final‐good producers and across suppliers within a production line, and we show how it can be taken to the data with international trade statistics. Combining data from the U.S. Census Bureau's Related Party Trade database and estimates of U.S. import demand elasticities from Broda and Weinstein (2006), we find empirical evidence broadly supportive of our key predictions. In the process, we develop two novel measures of the average position of an industry in the value chain, which we construct using U.S. Input–Output Tables.     

Capacity Allocation among Multiple Suppliers in an Electronic Market

An electronic marketplace typically provides industrial suppliers an alternative option for selling their capacity in addition to the traditional open market. However, suppliers face different sets of costs and risks in open market and in electronic market. Consequently, suppliers participating in an electronic market are likely to offer their capacity at a different price compared with traditional open market. We analyze this problem and derive the price‐capacity function for the supplier. We also derive a basis for allocating buyer's requirements among multiple suppliers so as to minimize his cost. Our model shows that suppliers with large capacities would quote a lower price in the electronic market. It also predicts that the unit bid price increases with bid quantity in the electronic market. Based on the price‐capacity curve, we model a scenario where the buyer announces, a priori, the number of suppliers to be selected for award of a contract that will minimize its costs.     

Flexibility or Cost Saving? Sourcing Decisions with Two Suppliers

This article studies a decentralized supply chain in which there are two suppliers and a single buyer. One supplier offers the quantity flexibility (QF) contract to the buyer, while the other offers the cheaper price. Under the QF contract, the buyer does not assume full responsibility for the forecast, yet the supplier guarantees the availability of the forecasted quantity with additional buffer inventory. On the other hand, the price‐only contract places full inventory burden on the buyer, but with a cheaper price. We study this problem from the buyer's perspective and solve for the buyer's optimal procurement and forecasting decisions. We identify areas where flexibility and cheaper price have an advantage, one over the other. Our results indicate that the buyer significantly benefits from having multiple sources of supply. We also find that, from the system's standpoint, a multisupplier system may outperform a single‐supplier supply chain under certain conditions. Interestingly, we observe that providing too much flexibility may benefit the low‐price supplier rather than benefiting the QF supplier. We discuss the managerial implications and provide directions for future research opportunities.