Optimal Acquisition and Sorting Policies for Remanufacturing

The condition of the used items acquired by remanufacturers is often highly variable, and sorting is an important aspect of remanufacturing operations. Sorting policies—the rules specifying which used products should be remanufactured and which should be scrapped—have received limited attention in the literature. In this paper, we examine the case of a remanufacturer who acquires unsorted used products as needed from third party brokers. As more used items are acquired for a given demand, the remanufacturer can be more selective when sorting. Thus, two related decisions are made: how many used items to acquire, and how selective to be during the sorting process. We derive optimal acquisition and sorting policies in the presence of used product condition variability for a remanufacturer facing both deterministic and uncertain demand. We show the existence of a single optimal acquisition and sorting policy with a simple structure and show that this policy is independent of production amount when acquisition costs are linear.     

Managing Demand Uncertainty through Core Acquisition in Remanufacturing

We discuss the optimal raw material acquisition strategy for a third party remanufacturer (3PR). We specifically investigate whether a 3PR should acquire used products or cores in bulk with uncertain quality levels, or in sorted grades with known quality levels; and whether to acquire and remanufacture cores before the demand is realized (planned acquisition), or after the demand is realized (reactive acquisition), or on both occasions (sequential acquisition). When only sorted cores are acquired, we find that, (i) it is optimal to acquire cores in multiple grades to balance acquisition and remanufacturing costs; (ii) if reactive acquisition is possible, it reduces the assortment size (number of grades in which cores are acquired) and the total inventory acquired in the planned acquisition; and (iii) the optimal portfolio of grades to acquire and the optimal acquisition and remanufacturing quantities of these grades can be determined analytically. When bulk cores are acquired in addition to sorted cores, the property of reduction in assortment size of the planned acquisition is preserved. We also show that the 3PR should acquire only a fraction of the demand in planned acquisition, and leave the rest for reactive acquisition. This fraction changes during the lifecycle of a remanufactured product. Using a combination of empirical and realistic data from a smartphone remanufacturer we show that sequential acquisition increases expected profit by up to 8% and 27% over only planned and only reactive acquisitions respectively, and reduces the inventory acquired by up to 21% over only planned acquisition.     

考虑不同回收质量等级的再制造系统回收生产决策

废旧产品的回收再制造过程往往在回收质量、再制造成本、再制造产出率、再制造产品需求等方面存在不确定性因素,极大地增加了再制造生产管理决策的复杂性。本文在一个回收再制造系统中研究了存在多种回收质量等级时的两阶段回收—再制造联合优化决策问题,并扩展到需求与价格相关和再制造产出率随机两种情形。在最大化再制造商期望利润的决策目标下,基于每种回收质量等级的单位回收和再制造成本构造出再制造系统的有效生产前沿面,给出了不同决策情形下再制造商的最优回收数量、销售定价的解析解,并且分析了一些主要的参数对再制造商最优决策的影响。本文的研究结果表明：（1）含有多种回收质量等级的再制造系统中存在一个下凸的有效生产前沿面,不在该前沿面上的任何质量等级的回收产品都将不会被用于再制造;（2）在同等的政府补贴额度下,回收补贴方式对再制造商决策的影响程度大于再制造补贴方式;（3）当再制造品的市场需求与价格相关时,最优销售价格至少大于第一种被使用的回收质量等级的边际回收和再制造成本;（4）任意两种回收质量等级之间存在着替代或互补效应,由其成本差异决定,并且这种效应随着需求不确定性的增大而增大;（5）再制造产出率的不确定性和再制造品需求的不确定性之间存在"对冲"效应,这种效应随着再制造产出率不确定性的降低而减弱。本文的研究可为不确定性环境下再制造企业的回收、生产管理决策提供有益的管理启示。     

考虑产品可替换的再制造产品选择决策

再制造是处理回收产品的一种重要方式.本文研究了一种简单的产品可替换的再制造决策模型,再制造商生产的产品有高质量和低质量两种,高质量的再制造产品数量超过需求量时,可以作为低质量产品的替换品销售.最后通过仿真算例说明了产品可替换策略比不可替换具有优势.     

动态定价与允许需求延迟订货批量模型的联合决策

基于MRP的经典订货批量模型往往忽略了产品的售价对订货策略的影响。本文针对离散时间多周期情形,研究了允许需求延迟的动态定价和订货批量的集成问题。建立了二次规划数学模型。提出了一种基于动态规划的精确算法,可以在多项式时间内求解原问题的最优定价策略和最优订货计划。实验结果表明,算法可以有效地求解动态定价和订货批量的集成问题;与串行决策机制相比,并行决策机制可以给订货商带来更多的利润。通过固定订货费用的灵敏度分析,揭示了固定订货费用对利润和订货计划的显著影响,表明了允许需求延迟的联合决策模型优于不允许需求延迟的联合决策模型。     

Stochastic lot sizing problem with controllable processing times

In this study, we consider the stochastic capacitated lot sizing problem with controllable processing times where processing times can be reduced in return for extra compression cost. We assume that the compression cost function is a convex function as it may reflect increasing marginal costs of larger reductions and may be more appropriate when the resource life, energy consumption or carbon emission are taken into consideration. We consider this problem under static uncertainty strategy and α service level constraints. We first introduce a nonlinear mixed integer programming formulation of the problem, and use the recent advances in second order cone programming to strengthen it and then solve by a commercial solver. Our computational experiments show that taking the processing times as constant may lead to more costly production plans, and the value of controllable processing times becomes more evident for a stochastic environment with a limited capacity. Moreover, we observe that controllable processing times increase the solution flexibility and provide a better solution in most of the problem instances, although the largest improvements are obtained when setup costs are high and the system has medium sized capacities.     

Lifecycle Pricing for Installed Base Management with Constrained Capacity and Remanufacturing

Installed base management is the policy in which the manufacturer leases the product to consumers, and bundles repair and maintenance services along with the product. In this article, we investigate for the optimal leasing price and leasing duration decisions by a monopolist when the production and servicing capacity are constrained. The effect of diffusion of consumers in the installed base is considered, with the ownership of the product resting with the monopolist during the product lifecycle. The monopolist operating the installed base jointly optimizes the profits from leasing the product/service bundle along with maintenance revenues and remanufacturing savings. We formulate the manufacturer's problem as an optimal control problem and show that the optimal pricing strategy of the firm should be a skimming strategy. We also find that the effect of remanufacturing savings on the pricing decision and the length of the leasing duration changes significantly depending on the duration of the product's lifecycle. If the product lifecycle is long and remanufacturing savings are low, the firm should offer a shorter leasing duration, whereas if the remanufacturing savings are high, the firm should optimally offer a higher leasing duration. In contrast, if the time duration of the product lifecycle is low and remanufacturing savings are low, the firm prefers to offer a shorter leasing duration, whereas if the remanufacturing savings are high, the firm should optimally have a longer leasing duration. The article also shows that if the production capacity is small, the manufacturer increases the leasing duration. If the production capacity is very small, the manufacturer sets the leasing duration to be equal to the product lifecycle and does not use remanufacturing.     

不同回收法律下的再制造供应链决策与合作研究

研究制造商责任制和分销商责任制两种回收法律体系对制造商和分销商的影响.针对不同法律体系下的供应链决策建立制造商作为斯塔伯格领先者的模型,研究这些回收法律下供应链成员的决策和收益.结果表明,不同的回收法律对供应链的总绩效不会产生影响,但是会通过回收可变费用影响收益在供应链成员之间的分配.此外,针对分散决策效率的不足,设计了在分销商责任制法律下基于回收品价格的价格折扣与回收补偿相结合的合作机制,促使供应链成员合作以使供应链总收益达到集中决策时的收益.     

Strategic Grading in the Product Acquisition Process of a Reverse Supply Chain

Most recommerce providers have moved to a quality‐dependent process for the acquisition of used products. They acquire the products via websites at which product holders submit upfront quality statements and receive quality‐dependent acquisition prices for their used devices. Motivated by this development of reverse logistics practice, the aim of this study is to analyze the product assessment process of a recommerce provider in detail. To this end, we first propose a sequential bargaining model with complete information which captures the individual behavior of the recommerce provider and the product holder. We determine the optimal strategies of the product holder and the recommerce provider in this game. We find that the resulting strategies lead to an efficient allocation, although the recommerce provider can absorb most of the bargaining potential due to his last mover advantage. In a second step, we relax the assumption of complete information and include uncertainty about the product holder's valuation of the product. We show the trade‐off underlying the recommerce provider's optimal counteroffer decision and analyze the optimal strategy, using a logistic regression approach on a real‐life dataset of nearly 6,000 product submissions. The results reveal a significant improvement potential, compared to the currently applied strategy.     

MRP Planned Orders in a Multiple‐Supplier Environment with Differing Lead Times

This study examines a deterministic material requirements planning (MRP) problem where lead times at subsequent ordering moments differ. Adequate replenishment methods that can cope with lead time differences are lacking because of the order crossover phenomenon, that is, replenishment orders are not received in the sequence they are ordered. This study specifies how to handle order crossovers and recalculate planned order releases after an update of gross requirements. The optimal (s, S) policy is based on dynamic programing. The state space is kept to a minimum due to three fundamental insights. The performance of the optimal solution approach is compared with two heuristics based on relaxations and a benchmark approach in which order crossovers are ignored. A numerical analysis reveals that average cost savings up to 25% are possible if the optimal policy is used instead of the benchmark approach. The contribution of this study is threefold: (1) it generalizes theory on MRP ordering, allowing for lead time differences and order crossovers; (2) it develops new fundamental insights and an optimal solution procedure, leading to substantial cost saving; and (3) it provides good‐performing heuristics for a general and realistic replenishment problem that can replace the current replenishment methods within MRP.     

配额——交易机制下动态批量生产和减排投资策略研究

随着我国碳排放交易市场的建立和发展,在碳排放约束下逐步降低单位产出的碳排放水平成为企业生产经营管理中的中长期约束性目标。本文在一个多周期决策模型中研究了配额-交易机制下企业的最优动态批量生产、碳排放权交易和减排投资联合决策问题。生产商在整个决策周期期初决定是否进行减排投资以及投资规模,根据每个周期的生产计划决定减排设备的运行计划。根据节能减排技术的特点,本文假设生产商运行减排设备时不仅降低了产品的单位生产碳排放量,而且降低了产品的单位生产成本。本文基于广义Benders分解法对模型进行了最优性分析,得到了最优生产决策和最优减排投资决策的一些基本性质,并通过数值实验分析了碳排放配额和碳排放权价格对生产商总成本、总排放以及减排投资决策的影响。本文的数值实验分析结果发现:(1)当碳交易市场上的碳排放权充足时,减少碳排放配额或改变碳排放配额的分配方式并不能影响生产商的碳排放水平;(2)碳排放权价格是影响生产商的碳排放水平和减排投资规模的关键因素;(3)随着碳排放权价格的上升,即使拥有足够的碳排放配额,生产商仍会不断提高减排投资规模以获得减排收益。研究结果对碳排放交易体系下生产企业进行减排技术投资具有较强的管理启示。     

有限分布信息条件下MTO再制造系统提前期优化

在只知道零部件再制造时间有限分布信息（即一阶矩、二阶矩）条件下,基于MTO再制造策略研究由再制件和采购件组成的再制品的提前期问题,该问题被描述为一个矩问题。以最小化库存持有成本和缺货成本为目标建立min-max优化模型,在具有相同一阶矩、二阶矩的分布集合中寻找使最坏分布下的目标函数值最小的最优再制造提前期。最后通过算例进行了验证,求解结果与传统假设再制造时间服从正态分布、均匀分布得到的结果吻合较好,但本文的方法更符合生产实际,能保证在具有同样一阶矩和二阶矩的所有分布情况下的解的鲁棒性,对企业制定再制造计划、采购计划等具有现实的指导意义。     

Effects of Random Yield in Remanufacturing with Price‐Sensitive Supply and Demand

In this study, we investigate the effects of recovery yield rate on pricing decisions in reverse supply chains. Motivated by the automotive parts remanufacturing industry, we consider an end‐of‐life product from which a particular part can be recovered and remanufactured for reuse, and the remainder of the product can be recycled for material recovery. Both the supply of end‐of‐life products and demand for remanufactured parts are price‐sensitive. Yield of the recovery process is random and depends on the acquisition price offered for the end‐of‐life products. In this setting, we develop models to determine the optimal acquisition price for the end‐of‐life products and the selling price for remanufactured parts. We also analyze the effects of yield variation to the profitability of remanufacturing, benefits of delaying pricing decisions until after yield realization, and value of perfect yield rate information.     

电子行业再制造逆向物流模式选择决策分析

电子行业的生产商始终是其逆向物流模式选择的主体,本文定量分析了三种回收处理模式的决策模型及其最优决策的基本性质.研究表明:从收益决策出发,自建回收处理系统总可以获得最大收益并可以以最低价格参与竞争.然而,其回收努力系数却可能最小;回收产品可再制造比率越大越能激发回收处理的积极性,获得较大的回收努力系数.结论指出生产商应该结合环保和法规要求根据各模式最优决策的性质选择合适的逆向物流运作模式.     

存在绿色消费者的再制造供应链信息分享策略

研究了制造商预测信息的分享对存在普通消费者及绿色消费者的再制造供应链的影响.建立并求解了集中模式、分散合作模式和分散竞争模式下信息无分享和信息分享的期望利润模型,并用比较和数值仿真的方法对结果进行了分析.研究表明:合作模式下信息分享对原制造商和供应链不利,对再制造商有利;竞争模式下信息分享对原制造商、再制造商、供应链均有利;当普通消费者支付意愿较小时,随着绿色消费者市场份额的增大,再制品需求上升,新产品需求下降;无论哪种决策模式,原制造商、再制造商和供应链的利润随着绿色消费者份额的增大而增大;集中模式下供应链的总利润大于两种分散模式.     

订单不确定条件下的供应链协同决策研究

在产品客户化程度较高的装配生产中,制造商在获得客户的订单需求信息,但订单尚未签订的情况下,往往就要求供应商开始生产订单所需的零部件,以便客户订单签订后可以立刻开始产品的装配生产,从而实现尽快向客户交付订单的目的。但是,在客户订单不确定条件下,供应商提前生产零部件存在着一定的风险。一旦客户订单最终未能签订,由于零部件客户化程度一般也比较高,在相当长一段时间内很难被其它订单消化,从而形成呆滞库存。本文基于这样的运作环境,通过数学建模分析,研究了制造商何时向供应商下达零部件订单最优,以及供应商的最优生产决策问题,并给出了具体的决策方法。最后通过算例验证了模型的结论,并分析了生产延滞成本分担系数对供应商和制造商双方期望利润的影响。     

Stabilized‐Cycle Strategy for Capacitated Lot Sizing with Multiple Products: Fill‐Rate Constraints in Rolling Schedules

In practice, deterministic, multi‐period lot‐sizing models are implemented in rolling schedules since this allows the revision of decisions beyond the frozen horizon. Thus, rolling schedules are able to take realizations and updated forecasts of uncertain data (e.g., customer demands) into account. Furthermore, it is common to hold safety stocks to ensure given service levels (e.g., fill rate). As we will show, this approach, implemented in rolling schedules, often results in increased setup and holding costs while (over‐)accomplishing given fill rates. A well‐known alternative to deterministic planning models are stochastic, static, multi‐period planning models used in the static uncertainty strategy, which results in stable plans. However, these models have a lack of flexibility to react to the realization of uncertain data. As a result, actual costs may differ widely from planned costs, and downside deviations of actual fill rates from those given are very high. We propose a new strategy, namely the stabilized cycle. This combines and expands upon ideas from the literature for minimizing setup and holding costs in rolling schedules, while controlling actual product‐specific fill rates for a finite reporting period. A computational study with a multi‐item capacitated medium‐term production planning model has been executed in rolling schedules. On the one hand, it demonstrates that the stabilized‐cycle strategy yields a good compromise between costs and downside deviations. Furthermore, the stabilized‐cycle strategy weakly dominates the order‐based strategy for both constant and seasonal demands.     

供应链中纵向信息获取和横向信息共享策略研究

研究由一个制造商和两个零售商组成的二级供应链中,零售商之间的横向信息共享策略和制造商的信息获取以及最优定价问题。在模型中,制造商同时为两家零售商提供等价商品,零售商向消费者销售商品且进行价格竞争。以Bertrand博弈为研究手段,求解了零售商的均衡销售价格、订货量决策和信息共享策略,制造商的最大利润和最优批发价格,以及供应链利润。分析比较了在制造商不同的信息获取策略下,零售商、制造商和供应链的利润。研究表明,零售商之间完全信息共享始终为占优策略。但制造商获取下游信息时会使得自身利润增加,零售商利润减少,因此零售商不会主动把信息共享给制造商。考虑到下游的边界均衡解,供应链的利润变化还与市场的不确定性和产品的替代性有关。当产品替代性较高或产品替代率较低且市场的不确定性处于中间水平时,制造商获取信息后供应链利润增加,此时制造商可以用部分增加的利润成功购买零售商信息。该模型为上游制造商提供了最优定价和信息获取策略,也为下游零售商提供了求解自身最优销售价格、订货量和信息共享决策的方法。     

一次提前订购下生鲜农产品的最优订货

针对生鲜农产品实体损耗一直困扰着农产品经营这一难题,研究由一个零售商和一个供应商组成的农产品订货问题。在零售商一次提前订购基础上,分别建立供应商一次供货和二次供货模型。经比较得到,二次供货下的最优订购量要大于一次供货下的最优订购量;零售商、供应商在二次供货下的最大期望利润要大于一次供货下的最大期望利润。最后,通过实例分析发现:二次供货下零售商和供应商一起承担了生鲜农产品损耗给供应链带来的风险;季中批发价的合理设定,可以使二次供货下的供应链对生鲜农产品损耗的抵御力更强。研究结论对我国进一步深入"农超对接"具有一定的指导意义。     

Optimal Pricing of Two Successive‐Generation Products with Trade‐in Options under Uncertainty

To entice consumers to purchase both current and next generation products, many manufacturers and retailers offer trade‐in programs that allow buyers of the first generation product to trade‐in the product and purchase the new generation product at a lower price. By considering the interactions between “forward‐looking” consumers and a firm when a trade‐in program is offered, we analyze a two‐period dynamic game to determine the optimal prices of two successive‐generation products in equilibrium, and examine the conditions under which trade‐in programs are beneficial to the firm. Our model incorporates market heterogeneity (valuation of the first generation product varies among the consumer population), product uncertainty (the incremental value of the new product is uncertain before its introduction), and consumers' forward‐looking behavior (consumers take future product valuation and prices into consideration when making purchasing decisions). With the trade‐in option, we show that consumers are willing to pay a price that is higher than their valuations of the current product. Furthermore, trade‐in programs are more beneficial to the firm when: (i) the durability of the current product is high; (ii) the market heterogeneity is low; or (iii) the uncertainty level (or the expected incremental value) of the new product is high. Finally, when the incremental value of the new product is more uncertain, consumers are more willing to purchase the current product because of the “option” value of the trade‐in programs and thus trade‐in programs can be more beneficial to the firm in this case.