质量约束下闭环供应链差异决策研究

针对由一原始设备制造商和一独立再制商所组成的闭环供应链系统,考虑到新品质量水平对独立再制商可回收量的质量约束效应,以及新品与再制品的价格及质量竞争,分别构建了原始设备制造商领导、独立再制商领导、无领导三种不同市场结构下闭环供应链决策模型,探讨了质量约束效应对闭环供应链运营的影响。研究表明:(1)三种市场结构下,新品和再制品两者在“质量水平-价格”两维度均有所差异,且市场地位的不对等有利于产品质量水平的共同提升;(2)质量约束效应的存在会对产品的价格和质量同时产生影响;(3)再制品具有质量劣势,且质量约束效应的增强,再制品质量劣势越大;(4)市场结构的变化及质量约束效应的强弱并不会影响市场总需求量,仅仅会影响成员企业的市场份额;在大多数情况下,消费者对新品需求更为活跃。但当原始设备制造商为市场领导者时,质量约束效应低于一阈值水平时,再制品销量反而高于新品销量;(5)无论从成员个体,还是从供应链整体,原始设备制造商为领导者的市场结构最有效,且新品质量约束效应并不会影响供应链总利润,仅影响成员企业在总利润中的分成;新品质量约束效应的增强更有利于原始设备制造商利润的改善,但同时会损害独立再制商利润。     

Two substitutable perishable product disaster inventory systems

A disaster inventory system is considered in which two substitutable items are stored for disaster management. In the event of disaster management, a particular product may become stock-out and the situation warrants that a demand for the particular product during its stock-out period may be substituted with another available similar product in the inventory. From the utility point of view, continuous review inventory models are quite appropriate in disaster inventory management. In this paper, a continuous review two substitutable perishable product disaster inventory model is proposed and analyzed. Since the inventory is maintained for disaster management, an adjustable joint reordering policy for replenishment is adopted. There is no lead time and the replenishment is instantaneous. For this model, some measures of system performance are obtained. The stationary behavior of the model is also considered. Numerical examples are also provided to illustrate the results obtained.     

Product availability in competitive and cooperative dual-channel distribution with stock-out based substitution

This paper investigates the impact of customers’ stock-out based substitution on the product availability and the channel efficiency of a dual-channel supply chain, which consists of a supplier distributing a single product to customers through both its wholly owned direct channel and an independent retailer. The supplier and its retailer, with the objective of optimizing their own profit, simultaneously choose their own base-stock level to satisfy the stochastic demand from the customers whose channel preferences are heterogeneous and may be affected by each channel’s product availability. The customers dynamically substitute between the two channels in the event of a stock-out. The result shows that the effect of the stock-out based substitution may increase or decrease the efficiency of a decentralized supply chain. It is found that while the integrated supplier–retailer may consolidate the base-stock levels to benefit from stock-out based substitution, the independent supplier and retailer are more inattentive to customers’ stock-out based substitution. Thus, the competitive base-stock levels of the decentralized dual-channel supply chain rarely agree with the system optimal levels. Various contracts are examined to shed light on channel coordination mechanisms. In addition, it is shown that the channel efficiency of the dual-channel distribution can be improved by the emergence of Stackelberg leadership from either the supplier or the retailer.     

基于经销商再制造的闭环供应链政府补贴策略及效果分析

针对制造商负责再制造设计,经销商负责再制造的闭环供应链系统,建立政府无补贴、补贴经销商再制造和补贴制造商再制造设计3种策略下的Stackelberg博弈模型,分析不同补贴策略对供应链成员企业决策的影响。同时,应用数值仿真方法研究相同补贴支出下两种补贴策略的优劣。结果表明:相对于无补贴策略,两种补贴策略均会降低再制品和新产品的销售价格,提高再制品销售量,提升再制造设计水平,并且在再制品需求量小于新产品需求量时均会降低新产品销售量,在再制品和新产品的需求量相等时均会提高新产品销售量;另外,在相同的补贴支出下,当新产品需求量大于再制品需求量时,补贴经销商更能降低两种产品的销售价格和新产品的销售量,提高再制品销售量和制造商与经销商的利润,补贴制造商则更能提升再制造设计水平。     

竞争型“以旧换再”闭环供应链策略选择及生产决策研究

针对两阶段闭环供应链系统,研究了古诺竞争型闭环供应链中的“以旧换再”策略选择问题。研究发现:(1)企业如何及何时实施“以旧换再”策略取决于自身及竞争企业的再制造水平。再制造水平不仅影响了企业的“以旧换再”数量,同时还会影响产品市场份额及利润。(2)“以旧换再”策略可以提高企业竞争力,增加企业产品市场份额和提高收益;(3)提高 “以旧换再”补贴及再制造产品接受度, 降低“二手市场”价格,均可以降低企业实施“以旧换再”策略和提高企业的“以旧换再”数量。     

网络效应影响下品牌商与模仿者的竞争策略

近年来,品牌商与模仿者的竞争问题引起了社会的广泛关注。本文构建了包含一个品牌商和一个潜在模仿者的两周期动态博弈模型,且消费者具有策略性行为。品牌商在第一周期是市场的垄断者,若模仿者在第二周期进入市场,那么第二周期会变成双寡头市场。模仿者入侵市场除了会引起竞争效应外,与品牌产品的相似性也会引起网络效应,从而增加品牌产品的市场接受度。因此,面对模仿者入侵,品牌商需要同时权衡竞争效应与网络效应两方面的影响。研究结果表明:(1)网络效应并不总是对品牌商和模仿者的价格和需求等产生积极影响。(2)模仿产品质量不可提升过高,当模仿产品质量和品牌产品质量过分接近时,两个企业的利润都会降低。(3)当网络效应较小或者模仿产品质量过高时,品牌商在双寡头市场的需求可能会高于垄断市场的需求。     

Coordination strategies in a three-echelon reverse supply chain for economic and social benefit

In addition to seeking profit maximization, reverse supply chains should further seek to maximize social benefit. Consequently, this paper investigates the coordination strategies among different parties in a three-echelon reverse supply chain consisting of a single collector, a single remanufacturer, and two retailers with complete information sharing. Additionally, this paper discusses four coordination strategies and performs a detailed comparative analysis on the optimal decisions of different models. Three numerical analyses are performed to show how the potential market demand of remanufactured products and the utilization ratio of used products affect the optimal total channel profit, recycle quantity and retail prices among four models in a reverse supply chain. The results indicate that optimal total channel profit and recycle quantity in a reverse supply chain are maximized in a centralized model. With the same potential market demand of remanufactured products and utilization ratio of used products, a centralized model maximizes the economic and social benefit compared to the other three models.     

基于回收风险的闭环供应链差异定价决策研究

随着资源的匮乏和环境污染的加剧,越来越多的企业和消费者开始关注废旧产品的回收再制造。针对制造商唯一寡头垄断市场竞争结构,引入回收风险,分别对制造商(OEM)自行回收废旧产品的闭环供应链、第三方回收商回收废旧产品的闭环供应链建立数学模型,分析给出各企业的最优差异定价规则,并从经济学意义上得到相关管理启示;数值实验的结果则进一步验证回购价格、回收风险、价格竞争强度对最优解的影响。研究结果表明:(1)闭环供应链结构会影响再制品价格及废旧产品的回收价格,但对OEM新品定价无影响。(2)回收风险的变化对价格决策的影响取决于闭环供应链的结构特征。当回收风险较低时,在激发消费者对再制品需求、促使消费者返回废旧产品、提升闭环供应链整体效率等方面,OEM自行回收模式优于第三方回收商回收模式;而当回收风险较高时,则第三方回收商回收模式优于OEM自行回收模式。(3)回收风险的降低使得闭环供应链总利润呈现出增长的趋势,进而进一步体现到再制造的经济价值。(4)OEM自行回收废旧产品需考虑到新品与再制品间的价格竞争强度,当价格竞争强度较弱时,OEM自行回收废旧产品可为OEM带来更多的利润;新品与再制品间的价格竞争也有利于再制品需求的提升。     

Profit maximization in an inventory system with time-varying demand,partial backordering and discrete inventory cycle

In this paper, an inventory problem where the inventory cycle must be an integer multiple of a known basic period is considered. Furthermore, the demand rate in each basic period is a power time-dependent function. Shortages are allowed but, taking necessities or interests of the customers into account, only a fixed proportion of the demand during the stock-out period is satisfied with the arrival of the next replenishment. The costs related to the management of the inventory system are the ordering cost, the purchasing cost, the holding cost, the backordering cost and the lost sale cost. The problem is to determine the best inventory policy that maximizes the profit per unit time, which is the difference between the income obtained from the sales of the product and the sum of the previous costs. The modeling of the inventory problem leads to an integer nonlinear mathematical programming problem. To solve this problem, a new and efficient algorithm to calculate the optimal inventory cycle and the economic order quantity is proposed. Numerical examples are presented to illustrate how the algorithm works to determine the best inventory policies. A sensitivity analysis of the optimal policy with respect to some parameters of the inventory system is developed. Finally, conclusions and suggestions for future research lines are given.

     

Capacitated dynamic lot sizing problems in closed-loop supply chain

In this paper, we address the capacitated dynamic lot sizing problem arising in closed-loop supply chain where returned products are collected from customers. These returned products can either be disposed or be remanufactured to be sold as new ones again; hence the market demands can be satisfied by either newly produced products or remanufactured ones. The capacities of production, disposal and remanufacturing are limited, and backlogging is not allowed. A general model of this problem is formulated, and several useful properties of the problem are characterized when cost functions are concave. Moreover, this problem is analyzed and solved to optimality using dynamic programming algorithms under different scenarios. It is shown that the problem with only disposal or remanufacturing can be converted into a traditional capacitated lot sizing problem and be solved by a polynomial algorithm if the capacities are constant. A pseudo-polynomial algorithm is proposed for the problem with both capacitated disposal and remanufacturing. The problem with capacitated production and remanufacturing and the problem with uncapacitated production and capacitated remanufacturing are also analyzed and solved. Through numerical experiments we show that the proposed algorithms perform well when solving problems of practical sizes. From the experimental results also indicates that it is worthwhile to expand the remanufacturing capacity only when returned products exist in a relatively long planning horizon, and production capacities have little effect on the remanufacturing plan when the demand is mainly satisfied by the production.     

Lot sizing with random yield and different qualities

This paper considers a production/inventory system where items produced/purchased are of different qualities: Types A and B. Type A items are of perfect quality, and Type B items are of imperfect quality; but not necessarily defective; and have a lower selling price. The percentage of Type A (the yield rate) is assumed to be a random variable with known probability distribution. The electronics industry gives good examples of such situations. We extend the classical single period (newsvendor) and the economic order quantity (EOQ) models by accounting for random supply and for imperfect quality (Type B) items which are assumed to have their own demand and cost structure. We develop mathematical models and prove concavity of the expected profit function for both situations. We also present detailed analysis and numerical results. We focus on comparing the profitability of the novel proposed models with models from the literature (and derivatives of these models) that develop the optimal order quantity based on the properties of Type A items only (and ignore Type B items). We find that accounting for Type B items can significantly improve profitability.     

Batch scheduling of deteriorating reworkables

The problem of scheduling the production of new and recoverable defective items of the same product manufactured on the same facility is studied. Items are processed in batches. Each batch comprises two sub-batches processed consecutively. In the first sub-batch, all the items are newly manufactured. Some of them are of the required good quality and some are defective. The defective items are remanufactured in the second sub-batch. They deteriorate while waiting for rework. This results in increased time and cost for their remanufacturing. All the items in the same sub-batch complete at the same time, which is the completion time of the last item in the sub-batch. Each remanufactured defective item is of the required good quality. It is assumed that the percentage of defective items in each batch is the same. A setup time is required to start batch processing and to switch from manufacturing to remanufacturing. The demands for good quality items over time are given. The objective is to find batch sizes such that the total setup and inventory holding cost is minimized and all the demands are satisfied. Dynamic programming algorithms are presented for the general problem and some important special cases.     

Waiting time in a multi-server cutoff-priority gueue, and its application to an urban ambulance service

We consider a priority queue in steady state with N servers, two classes of customers, and a cutoff service discipline. Low priority arrivals are "cut off" (refused immediate service) and placed in a queue whenever N1 or more servers are busy, in order to keep N-N1 servers free for high priority arrivals. A Poisson arrival process for each class, and a common exponential service rate, are assumed. Two models are considered: one where high priority customers queue for service and one where they are lost if all servers are busy at an arrival epoch. Results are obtained for the probability of n servers busy, the expected low priority waiting time, and (in the case where high priority customers do not queue) the complete low priority waiting time distribution. The results are applied to determine the number of ambulances required in an urban fleet which serves both emergency calls and low priority patients transfers.     

On a Profit Maximizing Location Model

In this paper we discuss a locational model with a profit-maximizing objective. The model can be illustrated by the following situation. There is a set of potential customers in a given region. A firm enters the market and wants to sell a certain product to this set of customers. The location and demand of each potential customer are assumed to be known. In order to maximize its total profit, the firm has to decide: (1) where to locate its distribution warehouse to serve the customers; (2) the price for its product. Due to existence of competition, each customer holds a reservation price for the product. This reservation price is a decreasing function in the distance to the warehouse. If the actual price is higher than the reservation price, then the customer will turn to some other supplier and hence is lost from the firm's market. The problem of the firm is to find the best location for its warehouse and the best price for its product at the same time in order to maximize the total profit. We show that under certain assumptions on the complexity counts, a special case of this problem can be solved in polynomial time.     

考虑外包的单产品再制造批量决策

在已有动态批量决策问题的基础上,考虑了再制造与外包这两个因素建立了单产品的再制造批量决策模型。对考虑外包的单产品再制造批量决策问题最优解的性质进行了讨论,在此基础上利用动态规划的思想给出了时间复杂性为O(T4)的算法,并用C++实现了本算法,实验表明本算法是有效的。     

Environmentally friendly facility location with market competition

Many traditional facility location models assume spatial monopoly where market competition is ignored. Since facility locations affect the firm’s market exposure and subsequently its profit, accounting for the impact of the location decisions on customers while anticipating the reaction of competitor firms is essential. In this paper, we introduce a competitive facility location problem where market prices and production costs are determined through the economic equilibrium while explicitly considering competition from other firms. In order to accommodate for the growing efforts on limiting carbon emissions, the presented model includes constraints on the amount of carbon emissions that are due to transportation, while allowing carbon trading. The problem is formulated as a mixed integer non-linear model. Through numerical examples, we illustrate the effect of market competition on the location decisions and discuss the impact of emission limits and carbon trading on customers.     

An optimal replenishment policy for deteriorating items with stock-dependent demand and relaxed terminal conditions under limited storage space

This paper deals with the problem of determining the optimal replenishment policy for deteriorating items with stock-dependent demand in which the terminal condition of zero-ending inventory is relaxed. In the model, shortages are allowed and partial backlogging/lost sales. That is, the zero/non-zero ending inventory models are considered simultaneously. The items in stock are displayed to the customers in shelves with limited storage capacity. In theoretical analysis, the necessary and sufficient conditions of the existence and uniqueness of the optimal solutions under various cases are shown. We then also provide a simple algorithm to find the optimal solutions for various situations. Further, a couple of numerical examples are presented to demonstrate the developed model and solution procedure, and several management insights are obtained from the numerical examples. Finally, sensitivity analysis of the optimal solution with respect to major parameters is also carried out.     

Competitive capacity expansion under demand uncertainty

We analyze the capacity expansion behavior of firms in a duopoly faced with an uncertain new market. The market demand may be high or low with a given probability mass function. Firms obtain private information about the market size and build their capacity before the market demand is known. Once the demand is revealed, firms enter a capacity constrained price competition phase which determines their revenues. Two scenarios are considered: first, when firms choose their capacities simultaneously in the investment phase, and second, when they do so sequentially. For each case, we determine the unique symmetric Nash equilibrium. Excess capacity can occur in equilibrium in the industry. It is seen that preempting the competitor in the capacity expansion phase offers first mover benefits. We argue that the sequential moves game is more prone to equilibrium excess capacity compared to the simultaneous case. We show that preemption is a good strategy if the investing environment is either highly optimistic or highly pessimistic. If the industry outlook is only moderately optimistic, a capacity planner is still better off preempting his competitor, however, the industry may encounter overcapacity as a consequence.     

A duopoly model with heterogeneous congestion-sensitive customers

This paper analyzes a model with two firms (providers), and two classes of customers. These customers classes are characterized by their attitude towards ‘congestion’ (caused by other customers using the same resources); a firm is selected on the basis of both the prices charged by the firms, and the ‘congestion levels’. The model can be represented by a two-stage game: in the first providers set their prices, whereas in the second the customers choose the provider (or to not use any service at all) for given prices. We explicitly allow the providers to split their resources, in order to serve more than just one market segment. This enables us to further analyze the Paris metro pricing (Pmp) proposal for service differentiation in the Internet.     

A multi-objective wholesaler–retailers inventory-distribution model with controllable lead-time based on probabilistic fuzzy set and triangular fuzzy number

This paper develops a single wholesaler and multi retailers mixture inventory distribution model for a single item involving controllable lead-time with backorder and lost sales. The retailers purchase their items from the wholesaler in lots at some intervals throughout the year to meet the customers’ demand. Not to loose the demands, the retailers offer a price discount to the customers on the stock-out items. Here, it is assumed that the lead-time demands of retailers are uncertain in both stochastic and fuzzy sense, i.e., these are simultaneously random and imprecise. To implement this behavior of the lead-time demands, at first, these demands are assumed to be random, say following a normal distribution. With these random demands, the expected total cost for each retailer is obtained. Now, the mean lead-time demands (which are crisp ones) of the retailers are fuzzified. This fuzzy nature of the lead-time demands implies that the annual average demands of the retailers must be fuzzy numbers, suppose these are triangular fuzzy numbers. Using signed distance technique for defuzzification, the estimate of total costs for each retailer is derived. Therefore, the problem is reduced to optimize the crisp annual costs of wholesaler and retailers separately. The multi-objective model is solved using Global Criteria method. Numerical illustrations have been made with the help of an example taking two retailers into consideration. Mathematical analyses have been made for global pareto-optimal solutions of the multi-objective optimization problem. Sensitivity analyses have been made on backorder ratio and pareto-optimal solutions for wholesaler and different retailers are compared graphically.