面临零部件过期的产品销售与售后服务供应链合同分析北大核心CSCDCSSCI

备件库存管理对产品售后服务至关重要,而零部件过期会影响备件库存的正常补货,进而延长故障修复时间,降低产品可用率.终身购买作为应对零部件过期的重要策略,被广泛运用在实践中.然而,学术论文中关于零件过期对供应链管理影响的研究并不多见.本文建立了同时考虑产品销售和售后服务情况下的供应链动态博弈模型,分析了客户的产品订购批量、供应商的定价决策以及备件终身购买批量之间的相互作用,探讨了保修期和零部件过期采购成本对合同均衡策略和供应链利润的影响•结果表明,当零部件过期采购成本较低时,供应商可以在延长保修期的同时降低备件库存数量,并允许一定程度的备件缺货水平,从而最大化提升产品可用率所带来的收益.同时,应当适当降低对备件数量的技术标准要求.而当零部件过期采购成本较高时,供应商应当避免提供较长的保修期,并增加备件终身购买批量以减小零部件过期带来的负面影响.此时,备件数量的技术标准则可以适当提高.     

基于绩效的产品维修服务合同最优设计与比较分析——考虑零部件过期的影响

基于绩效的合同 (Performance-based Contracts-PBC) 是近年来在产品售后维修服务领域出现的全新商业模式。PBC 改变了传统上供应商通过提供维修活动和销售零件获取收益的方式，将供应商最终实现的产品可用率作为客户付款的标准。在 PBC 模式下，供应商以提高产品可用率为目标，其运营管理决策需要重新审视。备件库存对维修服务十分重要，直接影响故障修复时间。而零部件过期会影响备件库存的正常补货，降低产品可用率。本文基于 Stackelberg 博弈框架，建立了两种不同惩罚机制PBC合同的供应链动态博弈模型，得出了供应商的最优合同设计方案和用户的最优产品订购批量，分析了博弈均衡策略之间的相互作用，探讨了备件过期应对策略对供应链成员最优利润的影响。结果表明，不同的惩罚机制会对供应链成员的决策产生不同的影响。相对于基于备件缺货数量的惩罚机制，基于用户停机损失的惩罚机制对供应商提高产品可用率具有更加强烈的激励效应。然而，这种惩罚机制会导致供应商对备件库存过度投资，并减少用户的产品购买数量，进而会降低供应链成员的最优利润。同时，一个有意思的结果是在基于备件缺货数量的惩罚机制下，供应链均衡状态中惩罚金额与批发价格有联动特征，使得罚金的大小不会对产品订单数量和备件库存数量产生单独的影响。     

基于Supply-hub的2个供应商单制造商批量协调问题研究

考虑一个由2个供应商和单制造商组成的装配型供应链,分析并建立了制造商、Supply-hub和2个供应商的平均成本函数,提出了分别由制造商和2个供应商负责Supply-hub营运及成本时的生产与订货批量模型。研究结果表明:当由制造商负责时,供应商距离Supply-hub越远,制造商的生产批量越大,且Supply-hub中的零部件补货批量相比供应商负责时更大;当由供应商负责时,制造商的生产批量不随供应商的远近而变化,供应商的零部件生产批量也不变。此外,在适用Supply-hub的条件下,相比由制造商负责,由2个供应商负责Supply-hub的运营并分担其成本时,整个供应链的总成本更低,2个供应商与制造商之间可以通过合理分配使2个供应商与制造商的营运成本均有所降低,从而实现整个供应链系统的Pareto优化。     

合作竞争下的供应商数量优化问题研究

从买主单一零部件采购总成本角度出发,建立了一个在合作竞争环境下确定零部件最优 供应商数量的模型. 该模型描述了影响零部件总采购成本的各种因素,包括市场环境、产品特 征、价格稳定程度、边际利润率、买主与供应商的相对讨价还价能力、合作竞争程度与合作成本 等. 通过对模型的求解与仿真分析,研究了这些因素对买主应选择的最优供应商数量的影响.     

基于供应链的汽车零部件采购管理分析

汽车供应链是最复杂、最典型的供应链体系,采购是这个供应链体系中非常重要的一个环节。本文基于国内汽车零部件产业发展现状的基础上,重点分析了如何通过企业内部之间以及与外部的协同采购作业,以达到降低整个供应链的成本。并提出了汽车零部件采购中供应商关系管理的维护和优化措施,这些将对汽车供应商关系管理有着重要的现实意义。     

供求不确定下零部件供应商横向协同研究

考虑了由2个供应商与1个制造商组成的按订单装配的供应链模型。在供应商的零部件供应不确定、制造商的客户需求不确定的环境下,从多供应商的视角来研究如何通过供应商之间形成零部件横向协同,向制造商齐套供应零部件,从而降低制造商的期望总库存成本。首先,建立了单周期和多周期的理论模型,并对形成协同前后的期望总库存成本进行了比较;然后,通过模拟仿真的方法,对模型进行验证和比较,并分析了不同的缺货成本对最优订单量、最优订至点和最小期望总库存成本的影响。结果表明,多供应商之间的零部件横向协同降低了制造商的期望总库存成本,提高了对客户需求的响应。     

供应链管理视野下制造企业采购管理的优化策略

供应链管理环境下,制造企业的采购管理有利于降低其采购成本、库存成本以及提高产品质量。尽管我国制造企业采购管理方面进行了积极探索,但是仍然存在着采购信息共享程度较低、采购质量控制力度不到位、供应商管理水平较为低下等问题。为此,就需要制造企业从加快采购信息化建设、实施供应链联合采购以及加强供应商管理等方面来加以优化。     

感知的创业激情、 信任与员工创新行为关系研究

实践中, 制造商可通过商业保险策略降低因零部件质量问题造成的经济损失.然而, 商业保险购买成本较高且可能导致供应商轻视质量问题, 放弃质量改进.为此, 本文基于完全信息下单周期两级供应链的采购合约决策模型, 研究制造商如何利用商业保险管理供应链质量风险的问题.通过比较研究, 找出商业保险策略的实施条件, 并给出最优采购合约及商业保险策略.研究结果表明: (1) 当供应商的企业规模较小、抗风险能力较低时, 商业保险策略可完全消除风险承受能力对双方交易的制约, 促进双方达成交易; (2) 当供应商的企业规模较大、抗风险能力较高时, 制造商可利用商业保险策略降低零部件采购价格, 提高期望利润; (3) 在商业保险策略下, 制造商的最优商业保险策略是全额投保; (4) 商业保险的实施不一定造成零部件质量水平的下降.当质量成本或供应商的风险承受能力较低时, 商业保险策略与质量改进之间具有互补效应.当风险承受能力和质量成本均比较高时, 商业保险策略与质量改进之间具有替代效应.     

不确定环境下的Supply-hub协同补货决策

个性化需求与零部件创新使得产品需求和补货提前期不确定,对供应链补货决策和运行成本产生重要影响。将提前期不确定因素引入Supply-hub协同补货研究中,探讨提前期随机和需求不确定情况下,考虑零部件配套性的三供应商单制造商生产两定制产品的Supply-hub协同补货决策问题;提出了三种补货策略,以供应链运行成本最小化为目标,建立不同策略下的供应链补货模型并求解最优补货批量和供应链最小运行成本;发现三种补货策略均存在唯一最优补货批量,基于Supply-hub的两种协同补货策略和基于分散决策的供应商独立补货策略各有优势,但基于Supply-hub的批量及时间协同的补货策略恒优于基于Supply-hub的集中补货策略。最后,通过MATLAB进行算例分析验证结论,发现基于Supply-hub的批量及时间协同的补货策略能有效降低需求不确定性带来的成本增加风险;通用件的提前期波动对于供应链期望运行成本的影响要高于定制件提前期波动的影响,因此在进行供应链补货策略选择时更加关注通用件提前期。     

供应链上考虑质量风险的经济批量分析

本文研究在一个供应商和一个制造商的供应链上,在考虑质量风险损失的情形下,供应商和制造商的订货批量策略.文章建立了一种综合考虑订货-库存成本和质量风险的供应链经济订货批量模型.首先,本文应用博弈理论对模型进行了分析,给出了非合作情况下最优批量解及其变化趋势;其次,应用优化理论分析了一体化情况下的最优批量解及其变化趋势.     

End‐of‐Life Inventory Decisions for Consumer Electronics Service Parts

We consider a consumer electronics manufacturer's problem of controlling the inventory of spare parts in the final phase of the service life cycle. The final phase starts when the part production is terminated and continues until the last service contract or warranty period expires. Placing final orders for service parts is considered to be a popular tactic to satisfy demand during this period and to mitigate the effect of part obsolescence at the end of the service life cycle. Previous research focuses on repairing defective products by replacing the defective parts with properly functioning spare ones. However, for consumer electronic products there typically is considerable price erosion while repair costs stay steady over time. As a consequence, there might be a point in time at which the unit price of the product drops below the repair costs. If so, it is more cost effective to adopt an alternative policy to meet service demands toward the end of the final phase, such as offering customers a new product of the similar type or a discount on a next generation product. This study examines the cost trade‐offs of implementing alternative policies for the repair policy and develops an exact expression for the expected total cost function. Using this expression, the optimal final order quantity and switching time from repair to an alternative policy can be determined simultaneously. Numerical analysis of a real world case sheds light on the cost benefits of these policies and also yields insights into the quantitative importance of the various cost parameters.     

Modellgestützte Flexibilitätsanalyse von Strategien zur Ersatzteilversorgung in der Nachserienphase

An important task in after sales service is the provision of spare parts for durables. Due to its nature and dependence on earlier sales, the demand for spare parts is inherently dynamic and uncertain requiring for high procurement flexibility. During the product life cycle, inventory management of spare parts is performed efficiently under use of flexibility provided by existing production facilities. This situation completely changes once the OEM ceases production of the parent product. A prime option of procuring spare parts for the End-of-production period is to place a final order for parts when regular production ends. Besides low unit production costs, this option does not contain any flexibility, yielding a high risk of obsolescence of stored parts, and at the same time a high risk of not being able to satisfy all demand during the service period. In order to increase flexibility further options like extra production at higher unit cost or remanufacturing of components taken from used products could be used. After introducing the problem and a basic quantitative model, we evaluate flexibility properties of strategies using different combinations of the above options. In doing so we distinguish between quantity, time, and stock related flexibility. In a comprehensive numerical study it is investigated to which extent flexibility properties of the different strategies can contribute to their economic profitability.     

Assessing End‐Of‐Supply Risk of Spare Parts Using the Proportional Hazard Model

Operators of long field‐life systems like airplanes are faced with hazards in the supply of spare parts. If the original manufacturers or suppliers of parts end their supply, this may have large impacts on operating costs of firms needing these parts. Existing end‐of‐supply evaluation methods are focused mostly on the downstream supply chain, which is of interest mainly to spare part manufacturers. Firms that purchase spare parts have limited information on parts sales, and indicators of end‐of‐supply risk can also be found in the upstream supply chain. This article proposes a methodology for firms purchasing spare parts to manage end‐of‐supply risk by utilizing proportional hazard models in terms of supply chain conditions of the parts. The considered risk indicators fall into four main categories, of which two are related to supply (price and lead time) and two others are related to demand (cycle time and throughput). The methodology is demonstrated using data on about 2,000 spare parts collected from a maintenance repair organization in the aviation industry. Cross‐validation results and out‐of‐sample risk assessments show good performance of the method to identify spare parts with high end‐of‐supply risk. Further validation is provided by survey results obtained from the maintenance repair organization, which show strong agreement between the firm's and the model's identification of high‐risk spare parts.     

Lifetime Buy Decisions with Multiple Obsolete Parts

Life‐cycle mismatch occurs when the life cycles of parts end before the life cycles of the products in which those parts are used. Lifetime buys are one tactic for mitigating the effect of part obsolescence, where a quantity of parts is purchased for the remaining life of a product. We extend prior work that determines optimal lifetime buy quantities for one product with one obsolete part by providing an analytic solution and two simple heuristic policies for the optimal lifetime buy quantities when many parts become obsolete over a product's life cycle. We determine which of our two heuristics is most accurate for different product life cycles, which yields a metaheuristic with increased accuracy. That analysis also reveals critical perspectives in making lifetime buy decisions with nonstationary life‐cycle demand patterns.     

End‐of‐Life Inventory Problem with Phaseout Returns

We consider the service parts end‐of‐life inventory problem of a capital goods manufacturer in the final phase of its life cycle. The final phase starts as soon as the production of parts terminates and continues until the last service contract expires. Final order quantities are considered a popular tactic to sustain service fulfillment obligations and to mitigate the effect of obsolescence. In addition to the final order quantity, other sources to obtain serviceable parts are repairing returned defective items and retrieving parts from phaseout returns. Phaseout returns happen when a customer replaces an old system platform with a next‐generation one and returns the old product to the original equipment manufacturer (OEM). These returns can well serve the demand for service parts of other customers still using the old generation of the product. In this study, we study the decision‐making complications as well as cost‐saving opportunities stemming from phaseout occurrence. We use a finite‐horizon Markov decision process to characterize the structure of the optimal inventory control policy. We show that the optimal policy consists of a time‐varying threshold level for item repair. Furthermore, we study the value of phaseout information by extending the results to cases with an uncertain phaseout quantity or an uncertain schedule. Numerical analysis sheds light on the advantages of the optimal policy compared to some heuristic policies.     

A PROFIT-MAXIMIZATION MODEL FOR A RETAILER'S STOCKING DECISIONS ON PRODUCTS SUBJECT TO SUDDEN OBSOLESCENCE

A product has been formally denned as being subject to sudden obsolescence if its lifetime is negative exponentially distributed. Using an approximate model, Masters suggested that the traditional method of incorporating obsolescence cost as a component of inventory holding costs in the economic order quantity (EOQ) model was appropriate-for products subject to sudden obsolescence, provided that the obsolescence cost component was computed properly. Unfortunately, current practice of the EOQ model seriously underestimates the costs of sudden obsolescence. An exact model demonstrating that Masters' model also underestimated true lifetime costs and overestimated the optimal order quantity has been presented. Neither of these models addressed quantity discounts. Furthermore, with their cost-minimization focus, these models fail to identify situations when minimized costs exceed expected revenues. We extend Joglekar and Lee's model to focus on maximizing profits, rather than minimizing costs. This model answers such questions as whether to stock the product at all, whether to accept a quantity discount offer, and what order quantity to use. Numerical examples and sensitivity analyses suggest that Masters' model provides a significant improvement over the traditional model in moving toward true optimality. However, they also illustrate situations where both the traditional and the Masters' model accept a quantity discount that deserves to be rejected and stock a product that should not be stocked. In such situations, it seems important that a retailer uses the profit-maximization model presented here.     

An Advanced Heuristic for Multiple‐Option Spare Parts Procurement after End‐of‐Production

After‐sales service is a major source of profit for many original equipment manufacturers in industries with durable products. Successful engagement in after‐sales service improves customer loyalty and allows for competitive differentiation through superior service like an extended service period during which customers are guaranteed to be provided with service parts. Inventory management during this period is challenging due to the substantial uncertainty concerning demand over a long time horizon. The traditional mechanism of spare parts acquisition is to place a large final order at the end of regular production of the parent product, causing major holding costs and a high level of obsolescence risk. With an increasing length of the service period, more flexibility is needed and can be provided by adding options like extra production and remanufacturing. However, coordinating all three options yields a complicated stochastic dynamic decision problem. For that problem type, we show that a quite simple decision rule with order‐up‐to levels for extra production and remanufacturing is very effective. We propose a heuristic procedure for parameter determination which accounts for the main stochastic and dynamic interactions in decision making, but still consists of relatively simple calculations that can be applied to practical problem sizes. A numerical study reveals that the heuristic performs extremely well under a wide range of conditions, and therefore can be strongly recommended as a decision support tool for the multi‐option spare parts procurement problem. A comparison with decision rules adapted from practice demonstrates that our approach offers an opportunity for major cost reductions.     

Product Design for Life‐Cycle Mismatch

Life‐cycle mismatch occurs when the life cycle of a product does not coincide with the life cycles of the parts used in that product. This is particularly a problem with products that contain electronic components that sometimes have life spans of only two years. The cost of mitigating component obsolescence, which may require redesigning the product, is often considerable. Thus, prudent product design necessitates the selection of electronic components and product architecture, considering the cost of mitigating an obsolete design and other costs related to the design and manufacture of a product. Accordingly, we develop and analyze a model that shows how a product design can be effectively tailored to a particular product's life cycle.     

考虑服务流的产品服务供应链网络均衡模型

产品服务供应链在向客户制造高质量产品的同时，也提供了产品全生命周期的专业服务，服务的嵌入增加了供应链协调的复杂性。考虑产品服务的双重需求，在分析各主体的运作行为的基础上，构建了包括多个制造商和多个销售商的多主体供应链网络；运用变分不等式刻画了制造商层、销售服务集成商层和需求市场的最优运作行为及其达成均衡的条件；最后，通过修正投影算法对数值算例进行了仿真。研究结果表明：产品服务供应链网络中的产品与服务均衡流相互影响，其中，服务水平直接影响到了产品需求；降低产品的售价将有利于服务价格和效益的提升。研究结论进一步印证了在产品服务供应链网络中承载于产品的服务将逐渐成为价值创造的主体。