【作者】 王德春；

【导师】 马祖军；

【作者基本信息】 西南交通大学 ， 管理科学与工程， 2010， 硕士

【摘要】 鉴于易腐品的特性,对其储存、运输等物流环节进行优化管理,可有效减少变质损耗,实现易腐品的及时配送,具有重要的理论和实际意义。在易腐品配送系统中,库存成本和运输成本占有很大的比重,且相互间具有密切的联系,因而有必要对两者进行集成优化研究,以便提高易腐品配送系统的整体绩效,即研究易腐品配送的库存—路径问题(Inventory-Routing Problem, IRP)。为此,本文从以下两个方面对易腐品配送系统的IRP进行了研究。首先,考虑了由配送中心和需求点组成的两级配送系统的IRP,把IRP分解为库存问题和路径问题两部分分别求解,最后采用提前配送的方法,对所求解进行迭代调整,以协调库存费、订货费、订购费用与运输费之间的关系,通过配送策略和订货策略的变换的不断迭代从而求得原问题的近似最优解。在制定库存策略时,就需求确定环境下考虑易腐品变质率建立了总成本包括订货费用、订购费用和库存费用在内的库存模型,为不同的需求点求得其最佳配送周期和配送量。算例结果表明,配送周期越短的客户越有可能通过提前配送产生成本节约,而全局调整成本的节约值是依靠尽可能地满足车辆的最大容载量来实现的。其次,针对易腐品配送中的运输问题,考虑城市路网中不同路段在不同时间段具有不同的行车速度,因此会对车辆的行驶时间造成影响,进而导致车辆在到达各个需求点时的到达时间也会因为跨时段而不同。因而在考虑具体每一天的配送策略时,需考虑时变因素。在此,论文采用了考虑时变因素的跨时段处理模型以及遗传算法,解决时间依赖条件下的VRP。更多还原

【Abstract】 In view of the characteristics of perishable items, optimizing the management of logistics links like storage and transportation would reduce deterioration effectively and distribute perishable items in time, so the optimal management has significant theoretical and practical meaning.In perishable items distribution system, inventory costs and transportation costs account for a large proportion, and there is a close relationship between inventory and transportation. In order to improve the overall performance, it is necessary to study inventory and transportation from the perspective of integration, that is to study on (Inventory-Routing Problem, IRP) in perishable items distribution system. Then, this paper study on IRP in perishable items distribution system from two aspects as follows.Firstly, this paper study on IRP in a two-level distribution system which is composed of distribution centers and demand points, and IRP is divided into two sub-problems: inventory-controlling problem and vehicle routing problem. Then a advanced distribution approach is proposed to iterate adjusting on the solution, aimed to coordinate the relationships among inventory holding cost, ordering cost, purchasing cost and shipment cost, then the approximate optimal solution can be obtained by iterating on the solution under different distribution strategy and order policy. In making inventory policy, considering the deterioration rate of perishable items under deterministic demand environment, a inventory model is established, in which the total cost is composed of ordering cost, purchasing cost and inventory holding cost. Based on the model we can get the optimal delivery cycle and quantity for each demand point. The example shows that the shorter delivery cycle, the customers are more likely to make cost saving through advanced delivery, while the cost saving by global adjustment is achieved by meetting the vehicle’s maximum load capacity as much as possible.Secondly, for transportation problem in perishable items distribution system, vehicle speed on different subsections in urban transportation network is varied according to different period of time, which will affect the travelling time and led to different arrival time. So, considering distribution strategy in each day, it is necessary to consider time-varying parameter. In this paper, a time-cross processing model incorporating time-dependent parameter is proposed and a satisfying solution is found for time dependent VRP by using genetic algorithm.更多还原