合同订购与现货市场混合交易下的双渠道供应链优化决策

为了更好地匹配需求与供应, 提高企业收益和服务水平, 本文研究了合同订购与现货市场交易结合下的双渠道供应链优化决策问题。首先分析了单纯批发价合同订购模式下的决策, 进一步考虑现货市场单向交易及双向交易的情形, 将供应链回购合同与数量柔性合同引入单向现货市场, 建立了这两类合同订购分别与现货市场补货、现货市场卖货相结合的订购模型, 以及批发价合同订购与现货市场买卖双向交易联合的决策模型。分析了不同模式下回购价格、缺货成本、补货成本、现货价格、现货价格波动及风险偏好对订购决策的影响, 并通过算例仿真, 分析了各类现货市场的使用对销售商收益的影响。结果表明, 合同订购与双向现货市场结合可以充分利用现货市场即时交易的优势, 提高供应链效益;而合同订购与单向现货市场结合, 虽然可以通过合同提高供货水平, 降低库存积压风险, 但该情形需要考虑供应商的回购或补货价格, 销售商仍有一定风险。不论单向或双向现货市场与合同订购的联合, 均可使供应链的利润优于单纯合同订购的情形。     

Optimal procurement of long-term contracts in the presence of imperfect spot market

B2B spot market has grown rapidly and become an effective trading channel for commodity products. Besides long-term contract procurement from conventional suppliers (forward and option), a buyer can procure or sell commodities at any time in B2B spot market to adjust her inventory level. However, spot prices are generally volatile and the market is imperfect in the sense that spot trading may be realized with uncertainty in a given period of time and often comes with extra transaction cost. This paper considers a commodity buyer who can order forward and option contracts in advance and trade in a B2B spot market when spot price and demand are observed stochastically. Based on a single-period newsvendor model, we discuss three optimal order strategies and derive respective expected profits when the buyer is risk-neutral. The sensitivity of purchase costs, market liquidity and transaction cost is investigated. We also compare the optimal expected profits for different strategies to illustrate the effects of the two long-term contracts in the presence of the B2B spot market. We then extend our model to a multi-period setting and derive the optimal strategy. Finally, we numerically compute the optimal order strategy for a risk-averse buyer and analyze the impact of spot market, risk aversion, as well as the correlation between customer demand and spot price.     

A Supply Chain with a Service Requirement for Each Market Signal

We study a single‐period two‐stage service‐constrained supply chain with an information update. The buyer has two procurement opportunities with the second one after observing a market signal, which updates the demand forecast. He also commits to a service level after observing the market signal. We derive his optimal ordering decisions and show that the critical market signal, the optimal first‐stage order quantity, and the optimal expected profit are monotone with respect to the target service level. We also discuss the impact of the forecast quality on the optimal decisions. We show that the optimal first‐stage order quantity may not be monotone with respect to information accuracy, as is in the case without the service constraint. In addition, we extend our analysis to the situation when an order cancellation is allowed upon the observation of the market signal. We also compare the results obtained for the problems with and without an order cancelation. Finally, we discuss the supply chain coordination issue and find that a buyback contract can also coordinate the supply chain in the presence of the service constraint.     

供应链单向及双向期权柔性契约比较分析

在随机市场需求环境下,对于易逝品供应链合作契约的数量柔性问题,建立了两种不同期权模式的柔性契约模型。通过对模型的求解与分析,得出了不同契约下销售商的订货策略,而且销售商在双向期权契约下比在单向看涨期权契约时的期权购买量要小,初始订货量要大,但总的预期订货量要小。销售商在两种期权契约模式下的总的最优订货量均大于传统订货方式下总的最优订货量。两种期权契约均可以提高销售商总的订货量,但在具体契约参数下,两者在接近供应链最优订货量上存在差异。     

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.     

基于双向期权的供应链柔性契约模型

对需求不确定性大、生产提前期长、销售季节短的产品的供应链合作问题,建立了基于双向期权的单期两级供应链数量柔性契约模型,研究得出了销售商最优初始订货量和期权购买量,而且与单向看涨期权契约相比,销售商的期权购买量减小,初始订货量增加,但总的预期订货量减小.供应商的最优产量需综合考虑产品的正常生产模式和快速生产模式的成本,以及销售商执行期权的预期.供应商的生产不确定受销售商执行期权的相关性影响,降低相关性可以降低生产风险.双向期权契约能够提高销售商的采购柔性、降低市场风险,但也减少了部分收益.供应商增加了部分风险,同时也获得收益补偿.最后.通过数值算例分析了论文中的研究结论.     

买方市场时效性产品的供应链弹性契约优化模型

在买方市场环境下,产品越来越具有时效性,寿命周期越来越短,为了规避风险,经销商往往不以实际预测量来订货。针对该问题,本文在已有的数量弹性契约研究的基础上,以激励相容理论和供应链理论为理念,引入回购契约的方法,提出了一个可以激励经销商的弹性契约优化模型,弥补了弹性契约的不足。用一个算例分析检验了该模型,结果表明,通过调节批发价格和返利比例来引导经销商的订货量趋势,当经销商期望利润最大的订货量与市场平均需求相等时,经销商会客观地估测未来需求量并报给制造商,同时制造商还在此基础上确定具体批发价格和返利比例以使自己利润最大化,从而使经销商与制造商共担供应链环节中的市场风险,并共同为优化整体供应链做出努力。     

Quantity Flexibility Contract in the Presence of Discount Incentive

We design a new contract, which we refer to as the QFi contract, that combines the quantity flexibility (QF) mechanism and the price‐only discount incentive. Under the QF contract, the buyer does not assume full responsibility for the forecast, yet the supplier guarantees the availability of the forecasted quantity and extra buffer inventory. In contrast, the price‐only discount contract places full inventory burden on the buyer. We show that the proposed QFi contract effectively balances the inventory risk for both the buyer and the supplier considering both the QF and discount mechanisms. We also show that the QFi contract is able to achieve supply chain coordination. More importantly, the QFi contract's coordinating price scheme does not require knowledge of demand distribution. We identify areas where the buyer and supplier may both benefit from implementing the QFi contract as opposed to the extant QF or price‐only (wholesale) discount contractual decisions in a decentralized supply chain. We also specify the conditions under which supply chain coordination can be achieved in a win‐win manner. We conclude with managerial implications and provide directions for future research.     

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.     

Optimizing Customer Forecasts for Forecast‐Commitment Contracts

We study a “Forecast‐Commitment” contract motivated by a manufacturer's desire to provide good service in the form of delivery commitments in exchange for reasonable forecasts and a purchase commitment from the customer. The customer provides a forecast for a future order and a guarantee to purchase a portion of it. In return, the supplier commits to satisfy some or all of the forecast. The supplier pays penalties for shortfalls of the commitment quantity from the forecast, and for shortfalls of the delivered quantity from the customer's final order (not exceeding the commitment quantity). These penalties allow differential service among customers. In Durango‐Cohen and Yano (2006), we analyzed the supplier's problem for a given customer forecast. In this paper, we analyze the customer's problem under symmetric information, both when the customer is honest and when he strategically orders more than his demand when doing so is advantageous. We show that the customer gains little from lying, so the supplier can use his control over the contract parameters to encourage honesty. When the customer is honest, the contract achieves (near‐)coordination of the supply chain in a great majority of instances, and thus provides both excellent performance and flexibility in structuring contracts.     

现货价格和需求关联时期权组合合约模式下采购风险管理策略

在现货价格和客户端需求关联的情形下,本文引用期权组合合约建立现货市场供应量有限时的两阶段采购风险管理模型,以期最大化零售商的期望收益。文中先用逆向归纳法列出零售商第二阶段的最优策略,采用标准扰动定理得出有效合约应满足的最优性条件,并将原模型转化为单调的最短路径问题,应用动态规划求解最优的采购策略。最后用算例分析了现货价格与需求的相关系数及现货市场的供应量对最优策略的影响,发现当供应量一定时,各有效合约的最优预订量及有效合约的总预订量都随着相关系数的增大而提高,并且有效合约受相关系数的影响大小取决于合约的灵活性;并且,当相关系数一定时,有效合约的总预订量及执行价格最低的有效合约的最优预订量都随着供应量的增加而单调减少。     

Asymmetric Forecast Information and the Value of Demand Observation in Repeated Procurement

In many supply chain relationships that continue over multiple periods, information about the hidden properties of the supply chain partners can be revealed throughout the course of the relationship. This article examines how the availability of such information affects the contracting scheme between a supplier and his manufacturer in a relationship that persists over several selling seasons. At the beginning of the first selling season, the manufacturer observes private information about the demand distribution, whereas the supplier who is less familiar with the market is endowed only with a prior belief about the market condition. When the supplier cannot observe the demand realization during the first selling period, she offers a contract that induces the manufacturer to reveal the market condition in the first selling season. However, the opportunity for the supplier to observe demand realization can result in the supplier offering the manufacturer a simple contract that does not induce the manufacturer to reveal his private information during the first selling season. In the latter case, the supplier observes the demand realization and designs the second period contract based on this information. We show that when the supplier chooses to offer such a contract, the manufacturer becomes worse‐off, and it has an ambiguous effect on the performance of the supply chain.     

多因素扰动情景下应急数量弹性契约的供应链协调

研究突发事件发生导致多种因素干扰的情景下,数量弹性契约是否能实现二级供应链协调,并寻找供应链协调时最优订货与定价策略。针对市场价格稳定和随机两种情况,设定契约弹性系数为常量,分别建立市场价格稳定不变与随机波动两种情况下的应急数量弹性契约模型,寻找它们实现协调的内在约束条件,并与基准模型下的结论进行比较。然后将契约弹性系数由常量拓展为变量,判断是否同时存在最优的弹性系数和订货量,分析弹性系数的变化对于生产、订货决策及供应链整体收益的影响。研究结果证明：当弹性系数为常量时,只要对基准契约的批发价进行适当调整,供应链就能协调应对两种情景下的突发事件,此时,可以找到唯一的最优订货决策。当弹性系数为变量时,两种情景下的供应链均不存在唯一的最优订货决策,但存在唯一的最优供货决策,并且契约弹性系数的改变不会影响供应链期望收益。最后通过算例验证了上述结论的正确性。     

Demand Forecast Sharing in Supply Chains

This paper examines the incentives of a manufacturer and a retailer to share their demand forecasts. The demand at the retailer is a linearly decreasing function of price. The manufacturer sets the wholesale price first, and the retailer sets the retail price after observing the wholesale price. Both players set their prices based on their forecasts of demand. In the make‐to‐order scenario, the manufacturer sets the production quantity after observing the actual demand; in the make‐to‐stock scenario, the manufacturer sets the production quantity before the demand is realized. In the make‐to‐order scenario, we show that sharing the forecast unconditionally by the retailer with the manufacturer benefits the manufacturer but hurts the retailer. We also demonstrate that a side payment contract cannot induce Pareto‐optimal information sharing equilibrium, but a discount based wholesale price contract can. The social welfare as well as consumer surplus is higher under the discount contract, compared with under no information sharing. In the make‐to‐stock scenario, the manufacturer realizes additional benefits in the form of savings in inventory holding and shortage costs when forecasts are shared. If the savings from inventory holding and shortage costs because of information sharing are sufficiently high, then a side payment contract that induces Pareto‐optimal information sharing is feasible in the make‐to‐stock scenario. We also provide additional managerial insights with the help of a computational study.     

产品召回供应链中线性保险合约与订货决策

考虑一个由单供应商和单制造商组成的二级供应链,在不确定市场需求情形下考虑产品召回,站在制造商角度研究供应链线性保险合约下的最优订货决策以及最优线性保险合约决策。研究表明,最优的订货决策与产品召回概率以及线性保险系数相关,存在唯一的最优订货量来最大化制造商的利润。对于密度函数倒数的导数较大的一般需求分布函数,最优的线性保险系数与线性保险合约的固定费用以及产品召回概率有关。当产品召回概率和线性保险合约的固定费用均较小时或者产品召回概率较大但线性保险合约的固定费用适中时,制造商通过选择线性保险合约可以改善自己的利润。     

Fresh-product supply chain management with logistics outsourcing

We consider a supply chain in which a producer supplies a fresh product, through a third-party logistics (3PL) provider, to a distant market where a distributor purchases and sells it to end customers. The product is perishable, both the quantity and quality of which may deteriorate during the process of transportation. The market demand is random, sensitive to the selling price as well as the freshness of the product. We derive the optimal decisions for the three supply chain members, including the 3PL provider's transportation fee, the producer's shipping quantity and wholesale price, and the distributor's purchasing quantity and retail price. We find that the presence of the 3PL provider in the supply chain has a significant impact on its performance. We propose an incentive scheme to coordinate the supply chain. The scheme consists of two contracts, including a wholesale-market clearance (WMC) contract between the producer and the distributor, and a wholesale-price-discount sharing (WDS) contract between the producer and the 3PL provider. We show that the proposed contracts can eliminate the two sources of “double marginalization” that exist in the three-tier supply chain, and induce the three parties to act in a coordinated way.     

不确定性环境下不同补货策略的供应链契约协调研究

针对产出和需求不确定性导致的残值或补货问题,考虑单个制造商和零售商所组成的双边随机供应链,双方采取事前订单形式,构建两种不同现货市场补货策略模型,研究随机环境下最优原材料投入量-成品订货量决策行为及供应链协调。研究表明：零售商自行补货时,收益共享合同不能分担上游产出不确定性风险,制造商为避免产出过剩会减小投入量导致合同失效,但融合了缺货惩罚-余货补偿双向机制的收益共享契约能够进行有效协调。当由制造商补货时,现货市场降低了产出不确定性风险且提高了系统产出投入比,并能重新使收益共享契约生效。此外,有效契约协调后的各方收益均为系统最优收益的仿射函数,并由协商后的收益共享比例控制着分配系数。理论分析和数值仿真说明了合同协调的有效性。算例分析还发现,设计的收益共享风险共担契约相比单一的收益共享契约能够更好地降低不确定性对收益的影响。     

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。     

A delay-in-payment contract for Pareto improvement of a supply chain with stochastic demand

We consider a supply chain consisting of a single supplier and a single retailer with stochastic customer demand, which is operated over an infinite horizon. We propose a delay-in-payment contract to coordinate the supply chain. With this contract, the supplier allows the retailer to pay partial order cost at the ordering epoch, and to pay the remaining portion after a permissible number of periods. The system is formulated as a stochastic dynamic programming problem. It is shown that there exists a base-stock policy to be optimal. Compared with the traditional wholesale-price contract, the delay-in-payment contract with appropriate parameters can achieve a Pareto improvement (i.e., the performances of both the supplier and the retailer using the delay-in-payment contract are better than those using the wholesale-price contract). Numerical studies are performed to investigate both the effectiveness of the Pareto improvement, and the impact of the major parameters of the delay-in-payment contract on the system performance.     

Channel Coordination for a Supply Chain with a Risk‐Neutral Manufacturer and a Loss‐Averse Retailer*

This articles considers a decentralized supply chain in which a single manufacturer is selling a perishable product to a single retailer facing uncertain demand. It differs from traditional supply chain contract models in two ways. First, while traditional supply chain models are based on risk neutrality, this article takes the viewpoint of behavioral principal–agency theory and assumes the manufacturer is risk neutral and the retailer is loss averse. Second, while gain/loss (GL) sharing is common in practice, there is a lack of analysis of GL‐sharing contracts in the supply chain contract literature. This article investigates the role of a GL‐sharing provision for mitigating the loss‐aversion effect, which drives down the retailer order quantity and total supply chain profit. We analyze contracts that include GL‐sharing‐and‐buyback (GLB) credit provisions as well as the special cases of GL contracts and buyback contracts. Our analytical and numerical results lend insight into how a manufacturer can design a contract to improve total supply chain, manufacturer, and retailer performance. In particular, we show that there exists a special class of distribution‐free GLB contracts that can coordinate the supply chain and arbitrarily allocate the expected supply chain profit between the manufacturer and retailer; in contrast with other contracts, the parameter values for contracts in this class do not depend on the probability distribution of market demand. This feature is meaningful in practice because (i) the probability distribution of demand faced by a retailer is typically unknown by the manufacturer and (ii) a manufacturer can offer the same contract to multiple noncompeting retailers that differ by demand distribution and still coordinate the supply chains.