An optimization model for reverse logistics network under stochastic environment by using genetic algorithm

Recovery of used products has become increasingly important recently due to economic reasons and growing environmental or legislative concern. Product recovery, which comprises reuse, remanufacturing and materials recycling, requires an efficient reverse logistic network. One of the main characteristics of reverse logistics network problem is uncertainty that further amplifies the complexity of the problem. The degree of uncertainty in terms of the capacities, demands and quantity of products exists in reverse logistics parameters. With consideration of the factors noted above, this paper proposes a probabilistic mixed integer linear programming model for the design of a reverse logistics network. This probabilistic model is first converted into an equivalent deterministic model. In this paper we proposed multi-product, multi-stage reverse logistics network problem for the return products to determine not only the subsets of disassembly centers and processing centers to be opened, but also the transportation strategy that will satisfy demand imposed by manufacturing centers and recycling centers with minimum fixed opening cost and total shipping cost. Then, we propose priority based genetic algorithm to find reverse logistics network to satisfy the demand imposed by manufacturing centers and recycling centers with minimum total cost under uncertainty condition. Finally, we apply the proposed model to a numerical example.     

A stochastic model for forward–reverse logistics network design under risk

Attention with reverse logistics networks has increased during the last decade since their economic impact has been increasingly important and as environmental legislation has been becoming stricter. In this paper, A multi-period multi-echelon forward–reverse logistics network design under risk model is developed. The proposed network structure consists of three echelons in the forward direction, (suppliers, facilities and distribution centers) and two echelons, in the reverse direction (disassembly, and redistribution centers), first customer zones in which the demands are stochastic and second customer zones in which the demand is assumed to be deterministic, but it may also assumed to be stochastic. The problem is formulated in a stochastic mixed integer linear programming (SMILP) decision making form as a multi-stage stochastic program. The objective is to maximize the total expected profit.     

基于第三方回收再制造逆向物流网络设计

针对再制造逆向物流网络设计问题, 在考虑产品回收量和消费市场需求量不确定的条件下, 以第三方物流企业收益最大化和制造商收益最大化为目标建立了基于第三方回收多周期再制造逆向物流网络模型. 利用该模型可以确定每个周期制造商购买第三方物流企业产品的最优价格, 可以确定网络中回收中心和检测/拆卸中心的开设数量以及各设施间的物流量分配. 将不确定参数用三角模糊数表示, 借助模糊机会约束规划方法将该模型转化为确定性等价模型. 利用算例验证了模型的有效性, 并用目标规划法分析了两个目标之间的关系.     

需求与物流网络不确定下的应急救援选址问题

针对应急物流中需求与物流网络的不确定性特征,对应急救援中应急需求和物流网络均不确定条件下的应急配送中心选址问题进行研究,以成本最小化为目标,建立基于集合覆盖的应急救援设施选址的随机规划模型,采用期望值法和随机模拟两种方法处理数学模型中的不确定性。通过算例与仿真研究,获得应急救援下的配送中心选址最优方案。结果表明,相对于传统的期望值方法处理随机参数,随机模拟方法具有较明显优势。     

An improved differential evolution algorithm for vehicle routing problem with simultaneous pickups and deliveries and time windows

The vehicle routing problem with simultaneous pickups and deliveries and time windows (VRP-SPDTW) is the problem of optimally integrating forward (good distribution) and reverse logistics (returning materials) for cost saving and environmental protection. We constructed a general mixed integer programming model of VRP-SPDTW. The model contained some classical vehicle routing problems as special cases. We proposed an improved differential evolution algorithm (IDE) for solving this problem. In the algorithm, we firstly adopted the novel decimal coding to construct an initial population, then used some improved differential evolution operators unlike the existing algorithm, and in mutation operation, we used an integer order criterion based on natural number coding method. We introduced a penalty technical to publish the infeasible solution. In addition, in the crossover operation, we designed a self-adapting crossover probability that varied with iteration. We did some numerical experiments, and the results showed that the proposed method is effective for solving VRP-SPDTW.     

Hybrid simulation-analytical modeling approaches for the reverse logistics network design of a third-party logistics provider

In this study, we consider a manufacturer that has strategically decided to outsource the company specific reverse logistics (RL) activities to a third-party logistics (3PL) service provider. Given the locations of the collection centers and reprocessing facilities, the RL network design of the 3PL involves finding the number and places of the test centers under supply uncertainty associated with the quantity of the returns. Hybrid simulation-analytical modeling, which iteratively uses mixed integer programming models and simulation, is a suitable framework for handling the uncertainties in the stochastic RL network design problem. We present two hybrid simulation-analytical modeling approaches for the RL network design of the 3PL. The first one is an adaptation of a problem-specific approach proposed in the literature for the design of a distribution network design of a 3PL. The second one involves the development of a generic approach based on a recently proposed novel solution methodology. In the generic approach instead of exchanging problem-specific parameters between the analytical and simulation model, the interaction is governed by reflecting the impact of uncertainty obtained via simulation to the objective function of the analytical model. The results obtained from the two approaches under different scenario and parameter settings are discussed.     

基于集成定位-运输路线安排问题的废旧家电逆向回收物流网络优化

针对废旧家电逆向回收物流成本高、效益差而导致其回收率低的问题,提出一种应用离散微粒群智能算法优化废旧家电逆向回收物流网络模型的方法。在系统分析废旧家电逆向回收物流网络结构与要素基础上,构建基于集成定位-运输路线安排问题的废旧家电逆向回收物流网络优化模型,引入随机交换序与部分映射交叉(PMX)算子使离散微粒群优化(DPSO)算法具备良好的全局及局部搜索能力,来对该模型进行智能优化与求解。实例仿真结果表明,通过该优化模型及算法得到的全局最优解具有良好的收敛性和有效性;同时,能有效降低废旧家电逆向回收物流运作总成本。     

再制造/制造系统集成物流网络扩展模型研究

研究了再制造／制造系统集成的物流网络扩展模型，给出了其选址一分配模型．该模型特点是：网络结构为闭环网络；正向物流中统筹考虑再生品和新产品的物流分配，再生品和新产品不能相互替代；解决了新建装配厂、存储批发商及拆解中心的选址问题．     

Network site optimization of reverse logistics for E-commerce based on genetic algorithm

Product returns have been viewed as an unavoidable cost for online sales, forfeiting any chance of cost savings. As competition pressure continues to mount in E-commerce, B2B or B2C, E-commerce corporations have begun to explore the possibility of managing product returns in a more cost-efficient manner by rescheduling the locations of recycling centers. However, few studies have addressed the problem of optimization of the numbers and location of collecting points, recycling centers and remanufacturing centers for E-commerce based on genetic algorithm. To fill the void in such a line of research, this paper proposes a genetic algorithm-based model that can solve the location-allocation optimization of reverse logistics for E-commerce. The usefulness of the proposed model and algorithm was validated by its application to an illustrative example dealing with logistics sites allocation from online sales.     

Analyzing alternatives in reverse logistics for end-of-life computers: ANP and balanced scorecard approach

Activities in reverse logistics activities are extensively practiced by computer hardware industries. One of the important problems faced by the top management in the computer hardware industries is the evaluation of various alternatives for end-of-life (EOL) computers. Analytic network process (ANP) based decision model presented in this paper structures the problem related to options in reverse logistics for EOL computers in a hierarchical form and links the determinants, dimensions, and enablers of the reverse logistics with alternatives available to the decision maker. In the proposed model, the dimensions of reverse logistics for the EOL computers have been taken from four perspectives derived from balanced scorecard approach, viz. customer, internal business, innovation and learning, and finance. The proposed approach, therefore, links the financial and non-financial, tangible and intangible, internal and external factors, thus providing a holistic framework for the selection of an alternative for the reverse logistics operations for EOL computers. Many criteria, sub-criteria, determinants, etc. for the selection of reverse logistics options are interrelated. The ability of ANP to consider interdependencies among and between levels of decision attributes makes it an attractive multi-criteria decision-making tool. Thus, a combination of balanced scorecard and ANP-based approach proposed in this paper provides a more realistic and accurate representation of the problem for conducting reverse logistics operations for EOL computers.     

An integrated model for closed-loop supply chain configuration and supplier selection: Multi-objective approach

Reverse logistics consists of all operations related to the reuse of products. External suppliers are one of the important members of reverse logistics and closed loop supply chain (CLSC) networks. However in CLSC network configuration models, suppliers are assessed based on purchasing cost and other factors such as on-time delivery are ignored. In this research, a general closed loop supply chain network is examined that includes manufacturer, disassembly, refurbishing, and disposal sites. Meanwhile, it is managed by the manufacturer. We propose an integrated model which has two phases. In the first phase, a framework for supplier selection criteria in RL is proposed. Besides, a fuzzy method is designed to evaluate suppliers based on qualitative criteria. The output of this stage is the weight of each supplier according to each part. In the second phase, we propose a multi objective mixed-integer linear programming model to determine which suppliers and refurbishing sites should be selected (strategic decisions), and find out the optimal number of parts and products in CLSC network (tactical decisions). The objective functions maximize profit and weights of suppliers, and one of them minimizes defect rates. To our knowledge, this model is the first effort to consider supplier selection, order allocation, and CLSC network configuration, simultaneously. The mathematical programming model is validated through numerical analysis.     

Reverse logistics network design with stochastic lead times

This work is concerned with the efficient design of a reverse logistics network using an extended version of models currently found in the literature. Those traditional, basic models are formulated as mixed integer linear programs (MILP-model) and determine which facilities to open that minimize the investment, processing, transportation, disposal and penalty costs while supply, demand and capacity constraints are satisfied. However, we show that they can be improved when they are combined with a queueing model because it enables to account for (1) some dynamic aspects like lead time and inventory positions, and (2) the higher degree of uncertainty inherent to reverse logistics. Since this extension introduces nonlinear relationships, the problem is defined as a mixed integer nonlinear program (MINLP-model). Due to this additional complexity, the MINLP-model is presented for a single product-single-level network. Several examples are solved with a genetic algorithm based on the technique of differential evolution.     

基于遗传模拟退火算法的多层设施选址方法

逆向物流网络是逆向物流系统高效运作的基础和前提,而设施的选址定位是逆向物流网络设计的核心问题.为此,提出一个多层设施选址模型,旨在构建由回收点、回收中心和生产点相结合的最佳逆向物流回收网络.根据模型特点,提出基于遗传模拟退火算法的求解方法,个体采用二进制十进制混合编码;提出基于Metropolis准则的特定遗传进化操作;设计顾客对回收点、回收点对回收中心的两个子分配算法保证所有约束的满足性.最后通过仿真实验,得到满意的设施选址方案.可见,选址模型和算法是一种有效的设施选址方法,具有一定的应用前景.     

Multiperiod and stochastic formulations for a closed loop supply chain with incentives

Reverse logistics network design problem we focus on is about locating distribution centers, inspection centers and remanufacturing facilities, and determining the acquisition price as well as the amount of returned goods to be collected depending on the unit cost savings and competitor’s acquisition price. We introduce the multiple periods setting and stochastic demand formulated by scenarios. We develop two mathematical programming models to determine the pricing strategy of the recovered products together with the optimal network that must be designed to be the most profitable closed cycle. Our methodology is based on a Golden Section Search with some flexibility that enables us to fix the used product acquisition price and then solve the model as an integer linear programming. Moreover, we establish dependent size fixed costs of opening a distribution, an inspection, and a remanufacturing centers, and show that they have a strong impact on the Golden Section search behavior.     

Developing a bi-objective model of the closed-loop supply chain network with green supplier selection and disassembly of products: The impact of parts reliability and product greenness on the recovery network

Closed-loop supply chain network (CLSCN) design aims to incorporate environmental considerations into the traditional supply chain design by including recycling, disassembly and reuse activities. A CLSCN incorporates the use and reuse of environmentally friendly products and materials supported by the design of an appropriate recovery, disassembly, and refurbishing network. In the design process, a trade-off must often be made between the need to maximize profit and maximize greenness. The latter is considered for several reasons including regulatory requirements, corporate responsibility and corporate image. In this paper, a bi-objective mixed integer programming model is developed and solved for a forward/reverse logistic network including three echelons in the forward direction (suppliers, assembly centers and customer zones) and two echelons in the reverse direction (disassembly and recycling center). A set of Pareto optimal solutions is obtained to show the trade-off between the profit and the greenness objectives. Some useful managerial insights are developed through various computational experiments.     

一种混合人工蜂群算法求解顺序相依拆卸线平衡问题

拆卸线平衡问题直接影响回收再制造成本.为此,构建了最小工作站开启数量、最短总拆卸时间、均衡工作站空闲时间、尽早拆卸有危害和高需求零部件的多目标顺序相依拆卸线平衡问题优化模型,提出一种混合人工蜂群算法.所提出算法在观察蜂跟随阶段采用分阶段选择评价法,以便更好地区分蜜源;在侦查蜂开采阶段构建基于全局学习的搜索机制,以提高开采能力.蜜蜂寻优过程中设计了简化变邻域搜索策略,提高了寻优效率.对比实验结果验证了模型的有效性和算法的优越性.     

A supply chain network with product remanufacturing and carbon emission considerations: a two-phase design

Growing awareness of environmental issues is prompting the development of sustainable supply chain management. Closed-loop supply chains in which used products can be returned for remanufacture are becoming increasingly popular. This paper introduces a two-phase approach to the design of supply chain networks taking into account carbon emission and remanufacturing. In the first phase, a continuous approximation model is used to design the forward supply chain network. The objective is to minimize the total forward network cost by simultaneously determining the number and the service areas of distribution centers (DCs) and the replenishment cycle time for DCs. A nonlinear optimization technique is used to solve the forward supply chain network design problem. In the second phase, a reverse supply chain network is formulated based on the results of the first phase to determine the optimal number and service areas of remanufacturing centers (RCs) and the replenishment cycle time for RCs. Finally, numerical analyses are conducted to show the solution approach and provide some managerial insights.     

A stochastic optimization model for integrated forward/reverse logistics network design

In this paper, we develop a stochastic programming model for an integrated forward/reverse logistics network design under uncertainty. First, an efficient deterministic mixed integer linear programming model is developed for integrated logistics network design to avoid the sub-optimality caused by the separate design of the forward and reverse networks. Then the stochastic counterpart of the proposed MILP model is developed by using scenario-based stochastic approach. Numerical results show the power of the proposed stochastic model in handling data uncertainty.     

Integrated multistage logistics network design by using hybrid evolutionary algorithm

Design and optimization of logistics is very important issue, which plans, implements and controls the efficient, effective forward and reverse flow and storage of goods, services and related information between the point of origin and the point of consumption in order to meet customers’ requirements. In this paper, we formulate an integrated multistage logistics network model with considering the direct shipment and direct delivery of logistics and inventory. In addition, we propose an effective hybrid evolutionary algorithm (hEA) to solve this problem: (1) we employ an extended priority-based encoding method, (2) combine a local search (LS) technique and (3) proposed a new fuzzy logic control (FLC) to enhance the search ability of EA. Finally, numerical analysis of case study is carried out to show the effectiveness of the proposed approach.     

New mixed integer approach to solve a multi-level capacitated disassembly lot-sizing problem with defective items and backlogging

The disassembly process has attracted mounting interest due to growing green concerns. This paper addresses the capacitated dynamic lot-sizing problem with external procurement, defective and backordered items, setup times, and extra capacity. The problem is to determine how many end-of-life products to disassemble during each period. We propose a new mixed-integer programming (MIP) approach to formulate the problem under study in order to maximize the disassembly-process gain, which is obtained as the difference between the revenue achieved by resale of the items recovered after disassembly and the costs tied to operating the disassembly tasks. Several numerical tests using the well-known CPLEX solver proved that this new model can find the optimal disassembly schedule for most test instances within an acceptable computational time. Furthermore, we led sensitivity studies on disassembly capacity, setup time and procurement cost. Test results validate the power of the suggested model and provide helpful insights for industry practitioners.