一类短生命周期产品的回购合同

在考虑短生命周期产品具有价格弹性的随机需求情况下,研究了基于供应链环境下的短生命周期产品回购合同策略,分别分析了零售商和供应商在没有协调情况下各自的最优决策以及在回购合同协调下双方的最优决策,推导出了在回购合同下零售商的最佳订货量和最优零售价,以及供应商的最优回购价格的取值范围,并通过数值分析,验证了在回购合同下双方的最优决策能使供应链的整体利润达到集中控制下的最优状态.     

Production control of hybrid manufacturing–remanufacturing systems under demand and return variations

Hybrid manufacturing systems that use both raw materials and returned products as a supply for their production process are considered. Specifically, the system under study contains two machines: one uses raw materials for manufacturing, while another utilises end-of-life products returned from the market for remanufacturing. Machines are failure-prone, demand and return rates fluctuate in time reflecting market behaviour due to economical, seasonal and environmental changes. The system performance is characterised by a long-term discounted cost that integrates several partial costs (those of manufacturing, remanufacturing, disposal, holding costs in serviceable and return inventories). Optimisation of the hybrid system behaviour requires to determine the combined manufacturing, remanufactruring and disposal policy, withstanding machine failures under dynamic market conditions. Optimality conditions in the form of Hamilton–Jacoby–Bellman equations are obtained and a novel numerical approach, based on the estimation of value function timederivative, is proposed in order to deal with demand and return variations. Extensive simulations are performed to address the numerous scenarios corresponding to evolving relationship between manufacturing capacities and varying demand and return levels. Simulation results show that the optimal policies have an important property of anticipating the future changes in the demand and return, and making the timely decisions relevant to these changes.     

Reverse Logistics: a stochastic EOQ-based inventory control model for mixed manufacturing/remanufacturing systems with return policies

This paper focuses on mixed manufacturing/remanufacturing systems, where manufacturing or purchase of new items integrates product reuse or remanufacturing, with the purpose to achieve a complete and timely demand satisfaction. We formulate a stochastic Economic Order Quantity (EOQ)-based inventory control model for a mixed manufacturing/remanufacturing system. The model is intended to identify the need of placing a manufacturing/purchasing order, to avoid the occurrence of stock-out situations. We then formulate a total cost minimisation problem, to derive the optimal return policy, this latter being a financial incentive paid to customers to increase the flow of returned items. The model developed is investigated through simulations, in order to assess the effect of stochasticity (of demand, return fraction and return delay) on the optimal return policy of the system; then, it is validated through a case study, to derive indications concerning its practical application in real cases. Our study ultimately provides a framework for practitioners to establish EOQ policies in reverse logistics contexts and to evaluate the opportunity of establishing a return policy in those contexts.     

信息不对称下多供应商与单零售商的退货策略

研究由多个提供互补组件的供应商和一个组装商组成的报童型供应链中,零售商将需求信息私有化时,供应商如何制定克服信息不对称的退货策略,使得零售商订货量和信息对称情况下供应链最优订货量相等。假设需求分高需求和低需求两种状态,供应商在需求状态未知的情况下给出针对不同需求状态的两个子契约,使得零售商按照实际需求状态而确定相应订货量。首先分析集权型供应链中整个供应链的最优订货量,再分析分权型供应链中零售商的订货决策,进一步分析信息不对称情况下供应商间的博弈及批发价和回收价契约参数的确定方法。通过算例,说明激励零售商按照真实需求状态选择子契约的合理性,供应商制定的退货策略可以克服信息不对称。     

An optimal dwell point policy for automated storage/retrieval systems with uniformly distributed,rectangular racks

This study is to develop an optimal dwell point policy for automated storage/retrieval systems with uniformly distributed racks. For non-square-in-time racks, we present the closed form solution for the optimal dwell point in terms of the probability of the next transaction demand type: storage or retrieval. We also introduce various return paths to the dwell point for the efficient operation of the storage/retrieval machine.     

考虑产品退货的制造商质量与服务决策研究

考虑由一个制造商与消费者组成的二级网购服务供应链,在产品质量、市场需求、价格等相关因素影响下,构建了网络直销的产品退货和服务水平决策模型。研究了这些相关因素的敏感系数变化对产品退货量和制造商最优决策的影响,并通过算例分析验证对比。结果表明,随着价格敏感系数的提高,制造商的最优价格、最优质量水平和最优服务水平均降低,产品退货量增多;随着服务水平敏感系数或质量水平敏感系数的提高,制造商的最优价格、最优质量水平和最优服务水平均提高,而产品退货量减少。     

考虑风险偏好的定价决策与需求信息共享价值分析

为了分析零售商的风险偏好对定价决策及信息共享价值的影响,以期望利润与条件风险估值的加权平均作为目标准则来刻画零售商的决策目标函数,构建供应链的需求信息共享决策模型,通过该模型,深入地分析和研究零售商不同风险偏好下供应链的最优定价决策以及需求信息共享的价值。研究表明,信息不共享情况下最优批发价与λ无关;当市场不确定信息显示需求增加时,最优批发价、最优零售价、零售商信息共享价值随着λ的增大而增大,而供应商和供应链的信息共享价值随着λ的增大而减小;而当市场不确定信息显示需求减少时,最优批发价、最优零售价、零售商信息共享价值随着λ的增大而减小,而供应商和供应链的信息共享价值随着λ的增大而增大。     

可回复多级库存系统的最优订货和回复策略

本文建立的可回复装配多级库存系统由两部分组成：缺陷零部件库存和产成品库存,其中产成品库存既可以通过零件维修、装配来补充,也可以直接从外部采购产成品获得。模型假设产品由两个可回复零件组成,且回收速率和外部需求是稳定的。通过建模和分析,得到了最优外部采购的经济订货批量,以及最佳装配策略和零件存储策略。     

电子商务环境下无缺陷退货政策

研究电子商务环境下包含一个制造商和一组顾客群的单周期供应链系统,建立了无质量缺陷的退货问题决策模型。分析顾客购买及退货的策略性决策的特点,确定了3种退货政策下,制造商的最优定价、最优供货量、最优退货价格及网络销售成本的临界值。比较分析3种退货政策的优劣及其对供应链绩效的影响。结果表明,当商品的采购/制造成本或残值较低时,零退货政策优于全额退货政策;而实行部分款额退货政策的供应链绩效优于全额退货政策。     

Efficient return algorithms for associated plasticity with multiple yield planes

A new return method for implicit integration of linear isotropic yield criteria is presented. The basic idea is to perform all the manipulations in the principal stress space and thereby achieve very simple formulae for calculating the plastic corrector stresses, based on the constant gradient of such criteria. The return formulae are in closed form and no iteration is required. The method accounts for three types of stress return: return to a single yield plane, to a discontinuity line at the intersection of two yield planes and to a discontinuity point at the intersection between three or more yield planes. The infinitesimal and the consistent elastoplastic constitutive matrix are calculated for each type of stress return, as are the conditions to ascertain which type of return is required. The method is exemplified with the Mohr–Coulomb yield criterion. Copyright © 2005 John Wiley & Sons, Ltd.     

Modeling returns of merchandise in an inventory system

Returns of merchandise occur commonly in the retail and rental businesses. This paper presents a new continuous review (s, S) inventory system with returns. The system is fairly complicated as its performance is a function of important factors such as demand rate, return time, return rate and replenishment frequency. Based on a Markovian approach, we derive essential operating characteristics of the system, and propose an algorithm to search for the optimal replenishment parameters. The results enable us to obtain valuable insights into the rental system, such as the impact of partial returns. Received: 12 November 1996 / Accepted: 18 December 1997     

基于不对称信息的闭环供应链激励机制

运用委托代理理论,分别对制造商能获得回收市场真实信息和无法获得真实信息两种情况,设计了提供给第三方的线性合同的,并基于报童模型给出了制造商的最优生产决策.最后用仿真试验研究了市场情况以及回收量与需求的波动对制造商利润的影响.     

Simple optimal replenishment and disposal policies for a product recovery system with leadtimes

The paper addresses a problem of product recovery management where a single product is stocked in order to fulfill a stochastic demand of customers who may return products after usage, thus generating also stochastic product returns. The material flow can be controlled by procuring new products on the one hand, and by remanufacturing or disposal of returned items on the other. A situation is considered where all costs are proportional and where remanufacturing as well as procurement needs a fixed deterministic leadtime which can be different for both activities. For periodic review control it is shown how the optimal decision rules for procurement, remanufacturing and disposal can be evaluated by exploiting the functional equations of a dynamic programming formulation. The serious impact of leadtimes on the complexity of the control rule is elaborated, and it is demonstrated for which leadtime situations simple optimal policies can be derived.     

Optimal order quantity and product modularity for a two-echelon returnable supply chain

This study considers a supply chain consisting of a manufacturer, a retailer, customers and a returnable and modular product with uncertain demand, in which customers return the unsatisfactory products to the retailer, and the retailer returns the unsold products to the manufacturer. We investigate the effects of the manufacturer’s refund for the retailer’s unsold products and the product modularity under the decentralised and the centralised strategies. We confirm that the order quantity and customer’s return probability both affect the optimal modularity level of the product, and that the optimal modularity level is related to the refund policy. Also, a strategic alliance between the supply chain members is more advantageous to product innovation based on modularity for a returnable chain. Finally, managerial insights and remarks are offered.     

Return policy in product reuse under uncertainty

One complicating factor in a reverse logistics activity is the uncertainty in the volume of the reverse product flow coupled with uncertain demand. These uncertainties are creating a problem for the reuse businesses because, in order to have a profitable business, their plants need some minimum number of used products to operate efficiently. Several researches have indicated that there is a significant quantity of used products that failed to enter the reverse channel. Therefore finding a way to ensure supply of used products is essential for the viability of the plant. In this paper, we propose the use of financial incentives (also referred to as ‘return policy’) so that adequate supply of the used products is ensured. We present a profit-maximisation model to obtain the optimal return policy. We also obtain a number of managerial guidelines for using marketing and operational strategy variables to influence the reaction parameters so as to obtain the maximum benefit from the market.     

Reliability functions for earthquake resistant design

A unified approach is presented for the establishment of design conditions and acceptance criteria for performance objectives associated with different return intervals. A life-cycle optimization analysis is adopted for this purpose. Reliability and expected damage functions are defined both for individual seismic events and for a long-term framework. System reliability functions are determined by Monte Carlo simulation for a number of multistory frames, designed for different base-shear ratios and subjected to earthquakes of different intensities. Systematic trends are identified about the variation of the reliability index with the natural logarithm of the expected ductility demand of a reference system. These trends lead to the definition of seismic reliability functions that can easily be adapted for applications to reliability-based design. The problem of transforming the results of the optimization studies into codified rules for practical design is briefly discussed.     

回购与缺货成本下的连续时间报童模型

对带回购策略与缺货成本的连续时间报童模型,研究了其最优订购策略与批发价策略,使得生产商和零售商期望收益最大化。在零售价格依赖需求过程与零售价格外生的两种情形下,讨论了带回购策略和缺货成本对连续时间报童均衡策略的共同影响。运用随机最大值原理研究了以上问题均衡策略的存在唯一性,讨论了均衡策略满足的条件,在价格外生情形下得出结论：回购策略与缺货成本的共同作用,使得零售商的最优订购量和供应商的最优批发价格均提高很多。最后,通过数值算例做了最优批发价格与最优订购策略的敏感度分析,具体例子验证了已得结论。     

Dynamic disassembly planning for remanufacturing of multiple types of products

With the increased need for remanufacturing of end-of-life products, achieving economic efficiency in remanufacturing is urgently needed. The purpose of this study was to devise a cost-minimisation plan for disassembly and remanufacturing of end-of-life products returned by consumers. A returned end-of-life product is disassembled into remanufacturable parts, which are supposed to be used for new products after being remanufactured. Each end-of-life product is disassembled into parts at variable levels and through variable sequences as needed, taking into account not only disassembly but also manufacturing, remanufacturing, and holding inventory of remanufacturable parts. This study proposes a mixed integer linear programming (MILP) model for derivation of the optimal disassembly plan for each returned product, under deterministically known demand and return flows. For the purposes of an illustrative example, the proposed model was applied to the formulation of an optimal disassembly and remanufacturing plan of ‘fuser assembly’ of laser printers. The solution reveals that variable-level disassembly of products saves a significant remanufacturing cost compared with full disassembly.     

Two-stage make-to-order remanufacturing with service-level constraints

We consider a firm that meets demand for an order with remanufactured products, new products or a mix of both. There are constraints on the service level. We use a stylized two-stage GI/G/ 1 queuing network model to study the problem. The first stage is unique to each product, whereas remanufactured and new products share the second stage. The objective was to find the optimal, long run production mix that maximizes profit subject to a service-level constraint that restricts the average order lead-time. There is yield in the remanufacturing process, where yield is the per cent of returned used products that result in a good part after remanufacturing. In the analytic model, we make the simplifying assumption that the producer always gets enough return of used products to meet its remanufacturing needs in the production mix. However, we relax this assumption in a simulation. We find that the optimal solution is generally non-trivial, i.e. the firm generally uses a mix of remanufactured and new products to meet demand. When the new product is less profitable than the remanufactured product, then it is optimal to remanufacture 100%, provided that there is enough supply of used products. When the new product is more profitable, however, the proportion of remanufacturing increases as service level increases. We use simulation to test the robustness of the analytic model by including complexities such as stochastic product returns and stochastic production yield.     

基于供应链金融的银行决策分析

根据需求模型,建立了包含银行在内的供应链决策模型,研究分散决策模型下的收益问题,分别得到供应链各个参与者的期望收益,并通过数值仿真,得到银行在供应链中产生的影响。从供应链金融的角度出发,研究零售商订购量、制造商批发价格、银行利率的关系。并利用Stackelberg博弈的理论,以银行为主导者,制造商和零售商为跟随者,求出均衡最优解。研究发现当市场需求较小时,三者收益函数趋势一致;当市场需求较大时,银行利率对零售商订购量没有影响并且银行的收益最后逐渐平稳达到一个固定值。