第3方冷链物流配送路径优化研究

根据冷链物流配送具有的特殊性,进一步探索冷链物流配送优化研究的方案.在保证货物不超载的情况下,建立以一个冷链配送中心、多个顾客的冷链物流的配送数学模型,用改进遗传算法加以分析求解,并采用Matlab软件对算法进行编程,最后通过算例进行验证.得到如下结论:利用改进遗传算法得到的最优配送路线优于标准遗传算法求解结果.     

震后应急物流设施不确定失效情景下的LRP研究

针对震后应急物流设施不确定失效情景下的定位-路径问题,综合考虑灾区路网存在部分损毁、应急物资多方式配送与运达时间限制等因素,以应急物流设施最坏失效情景下的需求点覆盖期望最大、应急物资总配送时间最短为目标,采用情景建模方法构建多目标定位-路径问题的数学模型,并根据模型特点设计基于分层序列法的两阶段混合启发式求解算法,第一阶段设计改进贪婪算法进行应急物流设施定位分配,第二阶段采用蚁群算法优化应急物资配送路线。最后,通过算例验证了本文模型和算法的可行性与有效性。     

多阶响应下军事物流配送中心可靠选址模型

为了提高战时物资配送的敏捷性和可靠性,结合军事物资配送的多阶响应过程,以部队用户对配送响应的时间约束为限制条件,以设施固定成本与期望配送成本之和为目标函数,并考虑设施未来失效的可能,建立了混合整数规划形式的军事物流配送中心可靠选址模型.结合模型的特点,采用基于时间约束的启发式算法将模型转化为可行子问题进行求解,使用仿真算例说明模型的优越性和算法的有效性.与不考虑设施失效的选址模型相比,考虑设施失效的选址方案在出现设施失效时,其应急配送成本平均增加量基本不超过设施固定成本的20％,平均最大增加量不超过25％;同一种失效情景下,考虑设施失效的选址方案的应急配送总成本也明显小于不考虑设施失效的选址方案的总成本.     

突发事件情景下串联式需求系统应急物资协同调度研究

针对突发事件情景下串联式需求系统遭受破坏问题,分析了突发事件情景下串联式需求系统应急物资协同调度的特征。在对系统提供应急物资进行修复的基础上,以串联式需求系统修复的时间最短及成本最小为目标,分别构建了纵向配送的应急物资调度模型和纵向配送与横向转运相结合的应急物资协同调度模型,并设计一种遗传算法对两种模型进行求解。最后通过算例分析,求解得到两种模式下串联式需求系统应急物资调度的最优配送方案,比较解的结果,得出纵向配送与横向转运相结合的应急物资协同调度模式优于一般的应急物资纵向配送模式的结论,验证了该应急物资协同调度模式的有效性和可行性。     

考虑道路可靠性的突发事件资源配送路线优化模型与算法

针对突发事件后道路网络的不确定性,定义了物资配送路线的风险度量值,然后建立考虑道路风险性的物资配送的优化模型以给出最优的路线安排方案,设计了基于禁忌搜索的模型求解算法,以某城市地震灾难后应急资源配送案例进行模型仿真.模型与算法的研究对于突发事件不确定道路网络下应急资源的配送决策具有很好的指导意义和实际意义.     

多储备点多品种应急物资配送的多目标优化模型

应急救援的社会化、应急物资需求的多样性、应急物资需求和补给的时变性,对应急物流的配送调度提出了挑战.应急物流的紧急性要求最大程度保障受灾点的物资供应;在经济上则要求应急物流的成本最小化.通过将时间离散化为阶段序列,在应急物资需求和补给是可预测的情况下,建立一个多储备点、多物资品种、单受灾点的应急物资配送的多目标优化模型,来最小化应急物资短缺次数和运输成本.仿真实例表明,该模型可以通过优化引擎快速求解,能够发现导致短缺的应急物资品种和加强供应补给的时间区间.     

基于HGA空间物资存储任务规划方法

针对物流领域物资存储任务规划问题进行研究。本文通过遗传算法（GA）结合启发式规则的思想,得到了在物资存储方面实用性较强的混合遗传算法（HGA）。该算法具备GA的优越性,并基于启发式规则对染色体信息及其组合进行优化和限定,依靠遗传算法的精英保留策略,避免了传统遗传算法常见的早熟收敛。仿真结果表明,该算法所得到的规划方法将不断逼近最优解,这就为三维空间物资存储任务规划提供合理方案,能显著提高效率。     

物流末端配送资源共享中政府作用演化博弈分析

资源共享是解决物流末端配送问题的有效途径,在企业各自为政无法进行配送资源共享的情况下,政府如何发挥作用才能激发各企业进行资源共享.构建物流企业与第三方服务平台关于共享物流配送资源的演化博弈模型,考察双方在物流配送末端的资源共享行为及其影响因素,分析政府在促进末端配送资源共享中的决策机理.得出政府不参与管理时,双方超额收益都高于所投入的额外成本才能促进资源共享;政府参与管理时,在双方资源共享成本接受范围内,政府的政策补贴行为能促进资源共享的发展.从机制设计角度分析未来政府参与管理对物流资源共享的促进作用,进一步提出相应的措施建议,从而为政府的机制设计提供一些思路.     

冷链物流同时送取货车辆路径优化

针对冷链物流同时送取货车辆路径优化问题,分析冷链物流配送中的车辆固定成本、行驶成本、制冷成本和货损成本等成本构成,以总成本最小化为目标,将冷链物流配送的送货和取货业务综合到每一个客户节点,建立单个配送中心和多个客户节点的冷链物流配送车辆路径优化模型,并采用遗传算法进行求解,算例分析验证了所建模型和设计算法的适用性和可行性,结果表明优化后的同时送取货车辆配送方案能够降低配送成本,提高配送效率,研究结论对冷链物流配送决策具有重要的参考价值.     

基于预判发货的网络零售商双模式批量配送研究

基于预判发货的背景,考虑订单处理中心和配送站之间存在第三方物流和自营物流两种配送模式,研究了B2C网络零售商的动态批量配送问题。首先利用混合整数规划构建了一个三级供应链系统下的动态批量配送模型,接着采用网络流规划的技术重新建模,并在其基础上对最优解的性质进行了分析,进而设计了计算时间复杂度为O(T²)的精确动态规划求解算法。最后用算例实验验证了该算法的有效性和适用性。     

盐业配送优化方案设计

本文讨论某盐业公司食用盐的最优配送方案.虽然该盐业公司沿用的配送方案,从人均劳动生产率来讲,居于行业之首,但还是比较原始的.我们建立了配送的运输模型,用计算机算出最优配送方案.它对该公司进一步改进组织构造,加强市场终端控制,整合供应链资源,有效实施计算机信息化,切实推进流通现代化有一定帮助.     

Optimal Solutions in the Multi-location Inventory System with Transshipments

We consider a single-period multi-location inventory system where inventory choices at each location are centrally coordinated. Transshipments are allowed as recourse actions in order to reduce the cost of shortage or surplus inventory after demands are realized. This problem has not been solved to optimality before for more than two locations with general cost parameters. In this paper we present a simple and intuitive model that enables us to characterize optimal inventory and transshipment policies for three and four locations as well. The insight gained from these analytical results leads us to examine the optimality conditions of a greedy transshipment policy. We show that this policy will be optimal for two and three locations. For the n location model we characterize the necessary and sufficient conditions on the cost structure for which the greedy transshipment policy will be optimal.      

“运价”为负的运输模型计算机求解问题的处理

为解决一些计算机软件求解"运价"既有正值又有负值运输模型时"不可求解"的问题,本文采用"运价同额增减法"决策模型转换的方法,将原模型的"运价"全部转换为正值后再用计算机软件求解,并分别编写了EXCEL求解模板和求解程序对该方法的计算加以印证。结果表明,采用该方法求解得出的最优解(最优决策方案)与原模型求得的最优解完全一样,而最优值(最优决策效果)减去虚增(或加上虚减)的部分就是原模型的最优值。采用这种方法能成功地解决一些计算机软件"不可求解"的问题。     

A Semi-Markov decision problem for proactive and reactive transshipments between multiple warehouses

Lateral transshipments are an effective strategy to pool inventories. We present a Semi-Markov decision problem formulation for proactive and reactive transshipments in a multi-location continuous review distribution inventory system with Poisson demand and one-for-one replenishment policy. For a two-location model we state the monotonicity of an optimal policy. In a numerical study, we compare the benefits of proactive and different reactive transshipment rules. The benefits of proactive transshipments are the largest for networks with intermediate opportunities of demand pooling and the difference between alternative reactive transshipment rules is negligible.     

基于批发价契约的多零售商横向转载的供应链协调

研究了多零售商横向转载的供应链批发价契约协调问题。以包含一个制造商和多个零售商的供应链系统为研究对象,基于批发价契约研究了零售商转载下的供应链协调问题,获取了批发价契约可以协调零售商存在横向转载的供应链的理论证据,并给出了相应的产生供应链协调的条件,详细分析了协调情形下供应链系统最优订货量与多零售商无转载及单报童等情形下的最优订货量之间的关系。进一步研究了制造商与零售商在Stackelberg博弈下,零售商横向转载对制造商收益的影响,并提出了在Stackelberg博弈模型中,批发价契约也有可能促使制造商选择供应链系统最优订货量所对应的批发价格,使得供应链协调,且给出了此种协调产生的具体条件。数值算例则对两种供应链协调情形下的订货量、批发价格及期望收益进行了计算与仿真。研究表明,批发价契约可能会使得多零售商存在转载的供应链实现协调,传统的双重边际化效应将会由于制造商和零售商的理性而被弱化。     

具有单向转载的Newsboy型产品订货决策的博弈模型

研究了允许单向横向转载的Newsboy型产品的订货决策问题。以两个Newsboy型零售商为研究对象,在允许单向横向转载存在的前提下,构建了以二者期望利润最大化为目标的非合作博弈模型,讨论了模型存在纳什均衡解的条件并证明了解的存在性与唯一性,给出了均衡解的解析表达形式,进一步分析了转载价格对均衡的影响。最后的算例分析则从期望利润、均衡订货和转载价格三个方面验证了横向转载策略的优势。研究表明:(1)与传统报童模型相比,横向转载策略提高了零售商的期望利润;(2)转载价格显著影响横向转载策略下零售商的订货决策。     

Optimal lateral transshipment policies for a two location inventory problem with multiple demand classes

We consider an inventory model for spare parts with two stockpoints, providing repairable parts for a critical component of advanced technical systems. As downtime costs for these systems are expensive, ready–for–use spare parts are kept in stock to be able to quickly respond to a breakdown of a system. We allow for lateral transshipments of parts between the stockpoints upon a demand arrival. Each stockpoint faces demands from multiple demand classes. We are interested in the optimal lateral transshipment policy. There are three ways in which a demand can by satisfied: from own stock, via a lateral transshipment, or via an emergency procedure. Using stochastic dynamic programming, we characterize and prove the structure of the optimal policy, that is, the policy for satisfying the demands which minimizes the average operating costs of the system. This optimal policy is a threshold type policy, with state-dependent thresholds at each stockpoint for every demand class. We show a partial ordering in these thresholds in the demand classes. In addition, we derive conditions under which the so-called hold back and complete pooling policies are optimal, two policies that are often assumed in the literature. Furthermore, we study several model extensions which fit in the same modeling framework.     

Managing transshipments in a multi-retailer system with approximate policies

Using the right transshipment policy is important when transshipments are exercised under demand uncertainty. Optimal transshipment policy can be quite complex in a multi-firm system as optimal actions depend on all system variables. Moreover, both how to select requested retailer and how to respond to requests are in question. We introduce simple, close-to-optimal heuristic transshipment policies for multiple retailers. We first show that heuristic policies may perform even better than self-optimal policy, which is explained by Braess’s paradox. Then we test the performances of various heuristics with respect to centrally optimal policy. When retailers can observe others’ inventory levels, more effective transshipments can be made. Otherwise, a random selection performs quite well. We also observe that although always-accept respond policy is quite close to centrally optimal in small systems, the performance of pairwise-optimal holdback levels to respond requests is more clear and consistent for larger systems.     

Asymptotic behavior of optimal quantities in symmetric transshipment coalitions

This paper addresses the asymptotic behavior of optimal quantities in symmetric transshipment coalitions. First, we provide bounds for optimal quantities under general demand structure. Second, we show that if the variance of average demand diminishes as the number of newsvendor grows, the optimal quantities move toward the distribution mean after coalitions became sufficiently large. However, the limits depend on the type of newsvendors in the coalition and the magnitude of transshipment cost above a certain threshold. We also discuss the pooling anomaly in large coalitions in these settings and show that the optimal quantities always decrease (increase) to their limit if the single newsvendor’s optimal quantity is above (below) mean.     

An index heuristic for transshipment decisions in multi-location inventory systems based on a pairwise decomposition

In multi-location inventory systems, transshipments are often used to improve customer service and reduce cost. Determining optimal transshipment policies for such systems involves a complex optimisation problem that is only tractable for systems with few locations. Consequently simple heuristic transshipment policies are often applied in practice. This paper develops an approximate solution method which applies decomposition to reduce a Markov decision process model of a multi-location inventory system into a number of models involving only two locations. The value functions from the subproblems are used to estimate the fair charge for the inventory provided in a transshipment. This estimate of the fair charge is used as the decision criterion in a heuristic transshipment policy for the multi-location system. A numerical study shows that the proposed heuristic can deliver considerable cost savings compared to the simple heuristics often used in practice.