考虑道路扩建的区域物流网络设计优化模型

通过对区域物流网络中边、点上费用、容量、流量等的分析,结合实际问题中对道路扩建和物流设施容量设计决策的需要,构建基于物流时间需求的区域物流网络设计数学模型。模型以最小化物流网络构建成本、初期运营成本和物流时间需求惩罚成本为目标,基于网络中物流量的特征给出了约束条件,分析模型的特点开发了改进的拉格朗日松弛算法并予以求解。计算机软件对模型和算法的仿真给出了物流网络构建中各项成本之间的关系,验证了模型和算法的有效性和实用性。     

浅谈计算机网络技术对物流信息化的影响

随着科学技术的进一步发展,我国计算机网络的发展前景喜人,为物流业实现信息化奠定了坚实的基础。物流信息化建设的不断推进,为建立物流业低成本、快捷、高效的配送体系提供了广阔的空间。本文主要分析了计算机网络技术在物流信息化建设中的作用,并阐明了其对物流信息化建设的突出影响,并以此为基础,进一步保证物流业的信息安全。     

A facility location model for logistics systems including reverse flows: The case of remanufacturing activities

After a brief introduction to the basic concepts of reverse logistics, we present a two-level location problem with three types of facility to be located in a specific reverse logistics system, named a Remanufacturing Network (RMN). For this problem, we propose a 0–1 mixed integer programming model, in which we simultaneously consider “forward” and “reverse” flows and their mutual interactions. An algorithm based on Lagrangian heuristics is developed and the model is tested on data adapted from classical test problems.     

A bi-level programming for logistics network design with system-optimized flows

This paper proposes a bi-level programming for a logistics network design problem with system-optimized flows. We applied the Wardrop’s second principle to the logistics network design problem. A system-optimized logistics network design problem can be formulated as a bi-level program. For the system-optimized flows, a user equilibrium traffic assignment problem with marginal costs can be solved at the lower level problem. Due to the non-differentiability of the perturbed solutions in system-optimized flows, we present a novel solution algorithm to efficiently solve the logistics network design problem. By using the subgradients of the objective function, a new projection method is proposed with global convergence. Numerical calculations are implemented using a grid-size hypothetical network and comparisons are made with other alternatives in solving the logistics network design problem. Numerical results disclose that the proposed method has successful solved the logistics network design problem and achieved significant performance both in computational efficacy and cost reduction when compared to other alternatives.     

Integrating the logistics network design with order quantity determination under uncertain customer demands

This paper aims to design an optimal logistics network including suppliers and retailers by taking into account the order quantity of products under uncertain consumer demand pattern. This research proposes a mixed-integer bi-level programming model and employs the iterative-optimization method. In the bi-level programming, the upper model is the logistics network design (LND) problem, which is designed for suppliers and consists of the hub locations, wholesale price of the products as well as the transportation flow of the commodity. The lower model is the order quantity determination (OQD) problem for retailers. It processes a special case of inventory problem in which the customer demand is stochastic and follows a series of assumed probability distributions. By applying the proposed methodology in a computational experiment, this research shows that if there were a large number of suppliers in the logistics system, retailers could order the product with relatively low price and the largest profit belongs to the retailer who could sell the commodity at the highest price.     

废旧产品回收再制造物流网络的优化设计模型

以总运作成本最小和对环境的影响最小为目标,建立了一个包含再制造工厂、回收中心和消费区域的三层逆向物流网络优化设计模型。并确定了物流网络中各种设施的位置和数量,以及由此构成的各条物流路径上的物流量分配。通过算例验证了模型的有效性。     

A linear relaxation-based heuristic approach for logistics network design

We address the problem of designing and planning a multi-period, multi-echelon, multi-commodity logistics network with deterministic demands. This consists of making strategic and tactical decisions: opening, closing or expanding facilities, selecting suppliers and defining the product flows. We use a heuristic approach based on the linear relaxation of the original mixed integer linear problem (MILP). The main idea is to solve a sequence of linear relaxations of the original MILP, and to fix as many binary variables as possible at every iteration. This simple process is coupled with several rounding procedures for some key decision variables. The number of binary decision variables in the resulting MILP is small enough for it to be solved with a solver. The main benefit of this approach is that it provides feasible solutions of good quality within an affordable computation time.     

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。     

随机中断下第三方物流弹复性网络设计*

实际环境下第三方物流（3PL）网络会面临各种不确定的中断风险。为了使3PL系统能够安全、有效的运作,研究3PL弹复性网络设计问题模型和算法。建立带有弹复性约束的3PL网络设计优化模型,通过选择开设3PL物流中心和3PL仓库最小化总物流成本,同时使弹复性满足要求水平。根据问题模型的NP特性,设计和声搜索(HS)算法进行求解,并采用蒙特卡洛仿真方法估算网络的弹复性。最后,通过仿真实验来验证模型的合理性及HS算法的有效性,并分析弹复性对算法性能和网络设计结果的影响 。仿真实验结果表明HS算法能够对问题进行有效求解。     

制造/再制造集成物流网络的优化设计研究

考虑到闭环物流系统中不同周期内各消费区域的产品需求数量、回收产品质量的不确定性,建立了多周期、有能力限制、正逆向物流集成运作的混合整数非线性规划模型。以总运营成本最少为目标,确定了制造/再制造集成物流系统中各种设施的数量、规模、位置以及各设施间的物流量分以配。通过算例验证了模型的有效性。     

物流服务供应链复杂网络脆弱性测度研究

合理评价物流服务供应链脆弱性是实现网络高效率的重要前提。分析物流服务供应链网络节点作用规律,引入聚集系数、最大连通度及连通效率作为网络脆弱性测度指标,基于所构建攻击策略对二级物流服务供应链网络进行实例研究。研究结果表明：所构建指标可较好描述物流服务供应链网络脆弱性能变化;相较于功能型物流服务供应商与物流客户,物流服务集成商对网络脆弱性影响程度最大。最后提出了物流服务供应链网络脆弱性的有效防范对策。     

A restricted dynamic model for refuse collection network design in reverse logistics

This study considers the problem of determining the locations of collection points as well as the allocations of refuses at demand points to collection points while satisfying the capacity and the maximum allowable collection distance constraints at each collection point. To consider fluctuating demands commonly occurred in refuse collection systems, we consider a restricted dynamic version of the problem in which the locations are fixed, but the allocations are changed over a given planning horizon. The problem is formulated as an integer programming model for the objective of minimizing the sum of fixed costs to open collection points and variable costs to transport refuses between demand and collection points, and then, due to the complexity of the problem, two heuristic algorithms are suggested. The heuristics, called the multi-stage branch and bound and the modified drop heuristics in this paper, are based on the decomposition of the entire problem into the static location and the dynamic allocation sub-problems. Computational experiments were done on various test instances, and the results are reported.     

基于变分不等式的多商品物流网络优化设计

为优化设计多级多商品流的物流网络,按网络状态把物流网络划分为静态网络和动态网络,分析了静态网络的基础设施建设和动态网络的物流活动问题,构建了可描述不同网络阶段的运营成本和建设成本函数,并且考虑了运营过程带来的环境污染问题,构建了治理费用函数。基于以上函数,建立以供给能力为约束条件,以总成本最小为目标的网络设计和重新设计模型,然后将模型转换为变分不等式问题,证明了所设计模型与变分不等式等价。最后通过算例,运用修正投影算法对模型进行数值演算和验证,得到了最优成本下的设施建设方案和物流组织方案。     

再制造混合物流网络的多周期多目标优化设计

考虑到产品生产和运输过程中对环境的影响以及产品的单位生产成本和生产批量之间的关联,以多周期内的总运营成本最少和对环境的有害影响最少为设计目标,并考虑到物流设施的能力限制和正逆向物流的集成运作,构建了制造/再制造集成物流网络的多周期优化设计模型。通过求解模型,确定了制造/再制造集成物流网络中各种设施的数量、位置、规模以及各设施间的物流量分配。最后,用算例验证了模型的有效性。     

Fill-rate service level constrained distribution network design

The design of distribution networks that simultaneously consider location and inventory decisions seeks to balance costs and product availability. The most commonly observed measure of product availability in practical settings is the fill-rate service level. However, the optimal design of a distribution network that considers the fill rate to control shortages of fast-moving consumer goods (FMCG) is considered intractable and has only been addressed by heuristic methods. This paper addresses the optimal design of a distribution network for FMCG able to provide high fill-rate service level under a continuous review $(r,Q)$ policy. Considering the exact formulation for the provided fill rate, we formulated a joint location–inventory model with fill-rate service level constraints as a convex mixed integer nonlinear problem for which a novel decomposition-based outer approximation algorithm is proposed. Numerical experiments have shown that our solution approach provides good-quality solutions that are on average 0.15% and, at worst, 2.2% from the optimal solution.     

Hybrid optimization and simulation to design a logistics network for distributing perishable products

Dynamics in product quality complicate the design of logistics networks for perishable products, like flowers and other agricultural products. Complications especially arise when multiple products from different origins have to come together for processes like bundling. This paper presents a new MILP model and a hybrid optimization–simulation (HOS) approach to identify a cost-optimal network design (i.e. facility location with flow and process allocation) under product quality requirements. The MILP model includes constraints on approximated product quality. A discrete event simulation checks the feasibility of the design that results from the MILP assuming uncertainties in supply, processing and transport. Feedback on product quality from the simulation is used to iteratively update the product quality constraints in the MILP. The HOS approach combines the strengths of strategic optimization via MILP and operational product quality evaluation via simulation. Results, for various network structures and varying degrees of dynamics and uncertainty, show that if quality decay is not taken into account in the optimization, low quality products are delivered to the final customer, which results in not meeting service levels and excess waste. Furthermore, case results show the effectiveness of the HOS approach, especially when the change from one iteration to the next is in the choice of locations rather than in the number of location. It is shown that the convergence of the HOS approach depends on the gap between the product quality requirements and the quality that can be delivered according to the simulation.     

A bi-objective reverse logistics network analysis for post-sale service

Reverse logistics, induced by various forms of return, has received growing attention throughout this decade. Reverse logistics network design is a major strategic issue. This paper addresses the analysis of reverse logistic networks that deal with the returns requiring repair service. A problem involving a manufacturer outsourcing to a third-party logistics (3PLs) provider for its post-sale services is proposed. First, a bi-objective optimization model is developed. Two objectives, minimization of the overall costs and minimization of the total tardiness of cycle time, are addressed. The facility capacity option at each potential location is treated as a discrete parameter. The purpose is to find a set of non-dominated solutions to the facility capacity arrangement among the potential facility locations, as well as the associated transportation flows between customer areas and service facilities. Then, a solution approach is designed for solving this bi-objective optimization model. The solution approach consists of a combination of three algorithms: scatter search, the dual simplex method and the constraint method. Finally, computational analyses are performed on trial examples. Numerical results present the trade-off relationship between the two objectives. The numerical results also show that the optimization for the first objective function leads to a centralized network structure; the optimization for the second objective function results in a decentralized network structure.     

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.     

回收不确定下WEEE逆向物流网络鲁棒优化设计

电子电器废弃物（WEEE）存在对环境和人体健康的危害,有效对其进行回收能避免此类危害和提高资源的利用率。WEEE逆向物流回收网络的设计为实现这一目标起到了关键的作用。考虑WEEE逆向物流网络运作的不确定性,引入风险偏好系数和约束背离惩罚系数,建立了WEEE逆向物流网络的鲁棒优化模型。该模型能允许决策者对系统运作的鲁棒水平进行调节,同时能允许决策者对风险偏好进行调节。仿真结果表明建立的模型能有效抑制逆向物流系统运作的不确定性,使系统具有更低的风险。     

铁路快捷货运班列轴幅式服务网络设计优化

为了使铁路快捷货物运输更加适应物流化的需求,研究轴幅式网络下铁路物流基地站间快捷货运班列服务网络设计问题.以固定成本、变动成本和惩罚成本最小为目标,构建单目标混合整数线性规划模型,同时囊括客户送达时间和班列服务等级要求,以及铁路线路通过能力限制,并结合模型特点和问题规模,设计遗传算法求解模型.最后,通过切实案例验证了模型和算法的有效性.算例结果表明,所提出的模型和算法可有效地描述和求解实际问题,同时,基于轴幅式网络的服务网络设计思路和方法对铁路快捷货物运输组织有一定的借鉴意义.