基于不同节点移动模式的无线自组网路由协议性能分析

本文采用NS2网络仿真软件,随机建立包含100个节点的网络拓扑,在节点静止、缓慢移动和快速移动条件下,分别对AODV、DSR和DSDV三种路由协议的数据包端到端时延、抖动和吞吐量的变化趋势进行比较分析。仿真结果表明,在网络规模较大且网络拓扑变化不频繁的情况下,DSDV具有一定的优势;在网络规模较大且网络拓扑多变的情况下,AODV和DSR性能明显优于DSDV。     

电子商务环境下基于B2C的物流配送路径优化

电子商务环境下的物流配送具有客户位置分散、订单多、批量小和重复线路多的特点,传统的线路优化方法都在不同程度上遇到各种问题。文中针对电子商务环境下的配送特殊性,采用改进两阶段算法混合进行求解。第一阶段用K-means聚类法将客户群分成若干区域,在每个区域又用扫描算法分解成若干符合约束条件的小规模子集;第二个阶段对各个分组内的客户点,就是一个个单独的TSP模型的线路优化问题,采用改进遗传算法进行优化求解。最后,结合具体实例,实验证明了该改进算法的有效性。     

有时间窗的车辆路径问题改进蚁群算法研究

针对目前蚁群算法在求解有时间窗的车辆路径问题上较少对蚁群算法本身进行优化的问题,提出了一种改进蚁群算法,通过改进状态转移概率和信息素更新规则,以及使用改进的精英蚂蚁策略,改善蚁群算法搜索能力。通过对Solomon标准数据集的实验,结果表明改进的蚁群算法在求解有时间窗车辆路径问题上是有效的。     

一类VRP问题的改进PSO算法求解

VRP问题是物流领域的热点研究问题。在对一类典型的VRP问题建立了数学模型,提出了一种改进粒子群优化算法以求解该模型。算法针对问题设计了顺序编码方案,并引入了局部搜索以提高算法的局部搜索能力。仿真结果表明了所提离散粒子群优化算法求解此类VRP问题的有效性。     

基于节约里程法的阳原县果蔬市场配送路线优化

高效率的物流配送是企业顺利运营和提高效益的重要条件,正确合理的设计公司的运输线路,可以有效节约人力、物力、财力、提高经济效益。文章在对蔬菜市场物流配送进行调查的基础上,建立配送优化路径模型并且进行了有效求解,提出了具体的物流配送线路优化方案,并结合运输中的实际情况,计算每次配送中的柴油的消耗费用和使用司机的成本,进行了总成本的节约优化。     

Inductive research in last-mile delivery routing: Introducing the Re-Gifting heuristic

The last-mile problem presents a daunting challenge for many logistics service providers, especially some 7000 small, localized operations for whom the cost of complex software solutions is often prohibitive. As a result, last-mile dispatchers rely on simple heuristics to ensure adequate customer service at an acceptable cost. This research effort extends prior qualitative work by developing and testing a simple vehicle routing heuristic, based on behaviors observed in practice, that prioritizes customer service over cost against other simple vehicle routing heuristics across a variety of environments using simulation. The results support the inclusion of a customer service focus in vehicle routing and the addition of such heuristics to existing algorithm portfolios, specifically in urban areas with well-developed highway systems.     

一种能耗均衡的无线传感器网络路由算法

为了延长采用电池供电的无线传感器网络的生命周期，提出了一种综合考虑单个节点能耗和节点传输信息至汇集节点所需总能耗的路由算法。该算法首先根据网络中节点到汇集节点从小到大的距离顺序选择待规划节点，然后计算各对应候选节点的评价参数，该参数由单节点能耗和节点传输信息至汇集节点所需总能耗加权得到，最后选择评价参数最小的候选节点作为待规划节点的中继节点。仿真结果表明，该算法的生命周期明显长于LEACH(Low Energy Adaptive Clustering Hierarchy)算法。     

Managing returnable transport items in a vendor managed inventory system

This paper addresses a closed-loop inventory routing problem with demand uncertainty, which manages the delivery operations to customers and pick-up operations of empty returnable transport items (RTIs) from customers. The problem involves decisions regarding forward and backward vehicle routes, the delivery and collection quantities, the amount of production in terms of the number of filled RTIs, and the number of RTIs produced/ bought by the vendor during the defined planning horizon. The problem considers the holding costs, fixed cost of operating vehicles, fuel consumption cost, producing/buying costs, cleaning costs of RTIs, and loading and unloading costs. We formulate the problem as a mixed integer linear programming model and propose a Relax and Fix based solution approach to solve large instances. We conduct extensive analyses on a case study derived from a fruit and vegetable distribution network and several hypothetical instances. Our analyses investigate the effects of several problem parameter changes (i.e., average collection rate, customer service level, cost of buying crate and handling cost) on the total logistics cost. Additional numerical analyses are performed to demonstrate the usage of the model for evaluating the cost of being more green and environmental-friendly. Moreover, experiments on relatively large-scaled problems allow us to demonstrate the potential benefits of the proposed heuristic     

一种最小误码率约束的动态地理协作路由算法

为了提高无线多跳通信的可靠性，提出一种联合物理层和网络层设计的动态地理协作路由(DGCR)算法，推导计算了单个协作单元协作中继节点的选择区域，在该区域内选择的协作中继节点可以满足误码率要求。最佳中继节点的位置会根据实际协作中继节点的位置和目的节点的位置动态选取。仿真计算表明，该算法相比非协作路由算法和传统地理协作路由算法具有更好的误码率性能，更适用于多径条件下的应用。     

无线传感器网络UDHR协议的设计与实现

针对无线传感器网络(WSN)数据流的特点,提出一种WSN上下行路由异构的协议(UDHR),上下行路由可采用不同的算法,适合于时间驱动、事件驱动以及查询的数据收集模式.利用OMNeT++平台对UDHR协议进行建模仿真,结果表明该协议开销小、扩展性好、健壮稳定.并且在自主开发的Testbed平台上实现了该路由协议,利用该平台可实时观察整个WSN网络拓扑变化、网络开销、监测每个节点能量消耗以及数据收集等情况.