Lot Sizing for Optimal Collection and Use of Remanufacturable Returns over a Finite Life‐Cycle

Reverse supply chains process used product returns to recover value by re‐processing them via remanufacturing operations. When remanufacturing is feasible, the longer the return flows are delayed during the active (primary) market demand period of the product, the lower the value that can be recovered through these operations. In fact, in order to recover the highest value from remanufactured products, the collection rates, return timings, and reusability rates should be matched with the active market demand and supply. With these motivations, this paper is aimed at developing analytical models for the efficient use of returns in making production, inventory, and remanufacturing decisions during the active market. More specifically, we consider a stylistic setting where a collector collects used product returns and ships them to the manufacturer who, in turn, recovers value by remanufacturing and supplies products during the active market demand. Naturally, the manufacturer's production, inventory and remanufacturing decisions and costs are influenced by the timing and quantity of the collector's shipments of used product returns. Hence, we investigate the impact of the timing of returns on the profitability of the manufacturer‐collector pair by developing system‐wide cost optimization models. Analyzing the properties of the optimal shipment frequency, we observe that the fastest reverse supply chain may not always be the most efficient one.     

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.     

政府补贴下制造商回收的多期闭环供应链网络均衡

为刻画闭环供应链系统运作的动态性和复杂性特点,本文在综合考虑环保约束和政府补贴等因素的基础上,建立了制造商回收模式下的多期闭环供应链网络均衡模型,其中假设市场需求在不同规划期内动态变化,渠道成员通过库存和旧产品的回收连接相邻规划期。运用变分不等式理论分别刻画了制造商层、零售商层和需求市场层的最优行为和均衡条件,进而推导整个多期闭环供应链网络均衡模型。通过投影收缩算法对数值算例进行求解和灵敏度分析,研究结果表明:再制造转化率的提高有利于各渠道成员和消费者利益的改善;尽管资源再生厂向制造商收取未再利用旧产品的处理费能够迫使其提高回收力度,但却导致零售商和闭环供应链收益的损失;政府应实施补贴机制并促进渠道成员之间的协作来改善闭环供应链网络的绩效。这些结论将为现实中闭环供应链节点企业的动态决策以及政府部门制定补贴政策提供支持。     

Delayed Differentiation for Multiple Lifecycle Products

Modular design allows several generations of products to co‐exist in the installed base as product designs change to take advantage of improved performance via modular upgrades. Use of a common base platform and modular design approach allows a firm to offer updates for improved performance and flexibility via remanufacturing when products have multiple lifecycles. However, as the product evolves through multiple lifecycles, the large pool of product variants leads to the curse of product proliferation. In practice, product proliferation causes high levels of line congestion and results in longer lead times, higher inventory levels, and lower levels of customer service. To offer insights into the product proliferation problem, the authors employ a delayed differentiation model in a multiple lifecycle context. The delayed differentiation model gives flexibility to balance trade‐offs between disassembly and reassembly costs by adaptively changing the push‐pull boundary. An adaptive, evolving push‐pull boundary provides flexibility for a remanufacturing firm to meet changing customer demands. The delayed differentiation model includes both a mixed‐integer linear program and an analytical investigation of the evolutionary nature of the push‐pull boundary. Both field observations and experimental results show that the nature of product proliferation and changing demand structures play significant roles in the cost and flexibility of the evolving delayed differentiation system.     

Closed‐Loop Supply Chains: A Critical Review,and Future Research*

In this article, I present a review and tutorial of the literature on closed‐loop supply chains, which are supply chains where, in addition to typical forward flows, there are reverse flows of used products (postconsumer use) back to manufacturers. Examples include supply chains with consumer returns, leasing options, and end‐of‐use returns with remanufacturing. I classify the literature in terms of strategic, tactical, and operational issues, but I focus on strategic issues (such as when should an original equipment manufacturer (OEM) remanufacture, response to take‐back legislation, and network design, among others) and tactical issues (used product acquisition and disposition decisions). The article is written in the form of a tutorial, where for each topic I present a base model with underlying assumptions and results, comment on extensions, and conclude with my view on needed research areas.     

The Reverse Supply Chain Planning Matrix: A Classification Scheme for Planning Problems in Reverse Logistics

This paper presents a conceptual planning framework for reverse supply chain operations based on an extensive literature review and industry expertise. Such a holistic scheme for classification of planning tasks is necessary as the intensification of research on reverse logistics and closed‐loop supply chains in recent years has raised a number of planning problems that differ from those of solely forward‐oriented supply chains. Up to now, a common and comprehensive definition of relevant planning problems along the reverse chain has not existed. Thus, a thorough understanding of the interdependence between these elements is missing. This paper aims to systematically identify planning problems, which are assigned to different planning horizons and distinct process stages of product recovery. The result is a classification scheme, called a ‘Reverse Supply Chain Planning Matrix’ (RSCPM), which categorizes planning problems and shows their interrelation in recovery operations. It serves both academia and practitioners as a holistic overview for planning and decision tasks. Moreover, decision‐makers are supported in identifying the relevant variables in reverse supply chains and in revealing the consequences of one decision regarding other parameters of the system. To the best of the authors' knowledge, the RSCPM is the first attempt to comprehensively structure the field of reverse supply chain research by identifying, defining and interconnecting planning problems within an integrated framework, as is common in the forward case.     

Supply Chain Sourcing in Remanufacturing Operations: An Empirical Investigation of Remake Versus Buy

Despite recent attention to closed‐loop supply chains and remanufacturing, there is scant information about what drives the re‐make versus buy decision for original equipment manufacturers (OEMs) engaging in remanufacturing. Based on the extant remanufacturing literature and transaction cost economics, we formulated hypotheses related to the drivers of in‐house versus contracted remanufacturing operations. The hypotheses were investigated via quantitative and qualitative data, thus offering a rich test of the formulated relationships. Consistent with the theory, the quantitative results showed that intellectual property, operational assets, and remanufacturing frequency are significant drivers of the re‐make versus buy decision. However, counter to the theory, the quantitative results did not support the significance of brand reputation, technological uncertainty, condition uncertainty, product complexity, and volume uncertainty. The qualitative results were used to enrich these findings by providing theoretical extensions and pragmatic insights of the remake versus buy decision in remanufacturing.     

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.     

Design of the Reverse Channel for Remanufacturing: Must Profit‐Maximization Harm the Environment?

A key attribute of a remanufacturing strategy is the division of labor in the reverse channel, especially whether remanufacturing is performed in‐house or outsourced. We investigate this decision for a retailer who accepts returns of a remanufacturable product. Our formulation considers the cost structures of the two strategies, uncertainty in the input quality of the collected/returned used products, consumer willingness‐to‐pay for remanufactured product, the extent to which the remanufactured product cannibalizes demand for a new product, and the power structure in the channel. For the profit‐maximizing retailer, the differentials in variable remanufacturing costs drive strategy choice, and higher fixed costs of in‐house remanufacturing favors outsourcing. The variable remanufacturing costs and the balance of power in the prospective outsourced reverse channel are the key drivers of environmental impact, as measured by the retailer's propensity to remanufacture. While profitability and environmental goals often conflict, they align under certain conditions. These include (a) the third party has less bargaining power; or (b) the fixed cost for in‐house remanufacturing is relatively high. All else equal, when remanufacturing is outsourced, the environment fares better if the third party has leadership power. We generalize to the cases when remanufacturing achieves a quality level less than “good‐as‐new" and when used items have non‐zero salvage value. Analysis of these extensions illuminates how relative power in the reverse channel drives the firms’ preferences, as well as the end customers’ consumption experience.     

THE IMPACT OF PRODUCT RECOVERY ON LOGISTICS NETWORK DESIGN

Efficient implementation of closed‐loop supply chains requires setting up appropriate logistics structures for the arising flows of used and recovered products. In this paper we consider logistics network design in a reverse logistics context. We present a generic facility location model and discuss differences with traditional logistics settings. Moreover, we use our model to analyze the impact of product return flows on logistics networks. We show that the influence of product recovery is very much context dependent. While product recovery may efficiently be integrated in existing logistics structures in many cases, other examples require a more comprehensive approach redesigning a company's logistics network in an integral way.     

The Value of Quality Grading in Remanufacturing

In this paper we consider a tactical production‐planning problem for remanufacturing when returns have different quality levels. Remanufacturing cost increases as the quality level decreases, and any unused returns may be salvaged at a value that increases with their quality level. Decision variables include the amount to remanufacture each period for each return quality level and the amount of inventory to carry over for future periods for both returns (unremanufactured), and finished remanufactured products. Our model is grounded with data collected at Pitney‐Bowes from their mailing systems remanufacturing operations. We derive some analytic properties for the optimal solution in the general case, and provide a simple greedy heuristic to computing the optimal solution in the case of deterministic returns and demand. Under mild assumptions, we find that the firm always remanufactures the exact demand in each period. We also study the value of a nominal quality‐grading system in planning production. Based on common industry parameters, we analyze, via a numerical study, the increase in profits observed by the firm if it maintains separate inventories for each quality grade. The results show that a grading system increases profit by an average of 4% over a wide range of parameter values commonly found in the remanufacturing industry; this number increases as the returns volume increases. We also numerically explore the case where there are capacity constraints and find the average improvement of a grading system remains around 4%.     

A decision support system for a third-party coordinator managing supply chain with demand uncertainty

Global supply chains reduce cost but increase lead times, complexities and uncertainties. Retailers in consumer products industry are getting shorter lead time to respond to market demand. To meet this challenge, many rely on third party supply chain managers (SCMs) for economically supplying required quantities of finished products quickly. However, due to shorter ‘time to market’, the SCM has to procure raw materials and start production process based on expected demand. Since SCM absorbs financial penalties associated with under- and over-estimation of demand from retailer, finding an optimal production lot size and product customisation strategy are essential to an SCM's operation. We develop a profit maximisation model and provide a close-form solution that allows an SCM to calculate optimal production lot size. The model is used to examine profitability of postponing product customisation. Finally, the effect of demand variation on SCM's profitability is explored.     

Take‐Back Legislation: Consequences for Remanufacturing and Environment

In the last two decades, many countries have enacted product take‐back legislation that holds manufacturers responsible for the collection and environmentally sound treatment of end‐of‐use products. In an industry regulated by such legislation, we consider a manufacturer that also sells remanufactured products under its brand name. Using a stylized model, we consider three levels of legislation: no take‐back legislation, legislation with collection targets, and legislation with collection and reuse targets. We characterize the optimal solution for the manufacturer and analyze how various levels of legislation affect manufacturing, remanufacturing, and collection decisions. First, we explore whether legislation with only collection targets causes an increase in remanufacturing levels, which is argued to be an environmentally friendlier option for end‐of‐use treatment than other options such as recycling. While increased remanufacturing alone is usually perceived as a favorable environmental outcome, if one considers the overall environmental impact of new and remanufactured products, this might not be the case. To study this issue, we model the environmental impact of the product following a life cycle analysis–based approach. We characterize the conditions under which increased remanufacturing due to take‐back legislation causes an increase in total environmental impact. Finally, we model the impact of legislation on consumer surplus and manufacturer profits and identify when total welfare goes down because of legislation.     

Joint Life‐Cycle Dynamics of New and Remanufactured Products

Many products considered for remanufacturing are durables that exhibit a well‐pronounced product life cycle—they diffuse gradually through the market. The remanufactured product, which is a cheaper substitute for the new product, is often put on the market during the life cycle of the new product and affects its sales dynamics. In this paper, we study the integrated dynamic management of a portfolio of new and remanufactured products that progressively penetrate a potential market over the product life cycle. To this end, we extend the Bass diffusion model in a way that maintains the two essential features of remanufacturing settings: (a) substitution between new and remanufactured products, and (b) a constraint on the diffusion of remanufactured products due to the limited supply of used products that can be remanufactured. We identify characteristics of the diffusion paths of new and remanufactured products. Finally, we analyze the impact of levers such as remanufacturability level, capacity profile and reverse channel speed on profitability.     

Addressing Supply–Demand Imbalance: Designing Efficient Remanufacturing Strategies

The management of remanufacturing inventory system is often challenged by mismatched supply (i.e., returned units, called cores) and demand. Typically, the demand for remanufactured units is high and exceeds the supply early in a product's lifetime, and drops below the supply late in the lifetime. This supply–demand imbalance motivates us to study a switching strategy to facilitate the decision‐making process. This strategy deploys a push mode at the early stage of a product's lifetime, which remanufactures scarce cores to stock to responsively satisfy the high demand, and switches to a pull mode as the product approaches obsolescence to accurately match the low demand with supply. In addition, the strategy further simplifies the decision‐making process by ignoring the impact of leftover cores at the end of each decision period. We show that the optimal policy of the switching strategy possesses a simple, multi‐dimensional base‐stock structure, which aims to remanufacture units from the i best‐quality categories up to the ith state‐independent base‐stock level. An extensive numerical study shows that the switching strategy delivers close‐to‐optimal and robust performance: the strategy only incurs an average profit loss of 1.21% and a maximum of 2.27%, compared with the optimal one. The numerical study also shows when a pure push or pull strategy, a special case of the switching strategy, delivers good performance. The study offers the managerial insight that firms can use simple, easy‐to‐implement strategies to efficiently manage the remanufacturing inventory system.     

Optimal Dynamic Order Scheduling under Capacity Constraints Given Demand‐Forecast Evolution

We consider a manufacturer without any frozen periods in production schedules so that it can dynamically update the schedules as the demand forecast evolves over time until the realization of actual demand. The manufacturer has a fixed production capacity in each production period, which impacts the time to start production as well as the production schedules. We develop a dynamic optimization model to analyze the optimal production schedules under capacity constraint and demand‐forecast updating. To model the evolution of demand forecasts, we use both additive and multiplicative versions of the martingale model of forecast evolution. We first derive expressions for the optimal base stock levels for a single‐product model. We find that manufacturers located near their market bases can realize most of their potential profits (i.e., profit made when the capacity is unlimited) by building a very limited amount of capacity. For moderate demand uncertainty, we also show that it is almost impossible for manufacturers to compensate for the increase in supply–demand mismatches resulting from long delivery lead times by increasing capacity, making lead‐time reduction a better alternative than capacity expansion. We then extend the model to a multi‐product case and derive expressions for the optimal production quantities for each product given a shared capacity constraint. Using a two‐product model, we show that the manufacturer should utilize its capacity more in earlier periods when the demand for both products is more positively correlated.     

碳税政策下闭环供应链网络均衡分析

针对由多个制造/再制造工厂和多个需求市场构成的闭环供应链网络，考虑两种碳税政策：单一比例碳税政策和超额累进碳税政策，分别量化两种碳税政策下工厂需支付的碳税，分析两种碳税政策下闭环供应链网络各成员企业的均衡条件，建立闭环供应链网络均衡模型，提出修正投影算法求解模型，最后，通过算例，对比分析两种碳税政策对闭环供应链网络成员企业新产品产量、网络间正向/逆向产品交易量、需求、价格、减排投资、碳排放量、碳税及成员利润的影响。     

EPR下供应链网络报废产品排放内生污染税模型

利用均衡理论及变分不等式研究工具,研究了生产者责任延伸(EPR)制度下的正向和逆向相结合的包含制造商、销售商/回收中心及需求市场的闭环供应链网络.考虑网络中各层决策者之间的相互作用,并与报废产品排放环境污染税相结合,建立了竞争环境中的多层供应链网络均衡模型,描述了网络中各层决策者的竞争行为,给出了供应链网络各层均衡及整...     

基于市场划分的再制造许可费对定价策略的影响

研究了基于市场划分的再制造许可费对闭环供应链定价策略的影响。考虑到再制造商具有只针对于绿色消费者进行销售的高价策略和针对于全体消费者进行销售的低价策略，基于回收量约束构建了包含一个原制造商和一个再制造商的Stackelberg博弈模型，求解两类定价策略下的最优决策。分析表明存在再制造许可费取值区间，当再制造许可费在不同的区间时，原制造商将通过在闭环供应链中的领导者地位迫使再制造商决定不同的定价策略。最后通过数值分析验证了再制造许可费的取值区间以及不同许可费时的闭环供应链定价策略和利润。