运用策略路由解决网络多出口问题

为了减轻互联网经营中的流量成本压力,可以租用网通、电信的第三方通道。为了克服网通、电信之间的互联瓶颈,采用策略路由,判断数据包的源地址、目的地址,从而实现流量智能转发。     

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研究在具有过去的统计信息及实时信息条件下的交通网络上的路径生成问题 我们假定路段通行时间具有一定的概率分布，这一分布从过去的统计数据得到，而当旅行者到达某一节点时，以该节点为起点的路段的通行时间作为实时信息被告知。在以上条件下，我们给出一种自适应算法来实时地生成一条路经，使得在某一预定时刻以前到达目的地的概率最大这个概率是衡量路径的时间可靠性的尺度，因而我们称相应算法为reliable routing algorithm。与之对应，我们注意到在以往的研究中，衡量路径优劣的有平均通行时间长短等等尺度。     

带回送和时间窗的车辆路径问题的模型及算法

在分析具有回送运输和时间窗的车辆路径问题特点的基础上，建立了该问题的优化数学模型，并通过设置与发货点距离为零的虚拟集货点使问题简化．在此基础上，构造了求解问题的改进遗传算法．在算法中，结合问题的特点设计了确保个体编码有效性的OX交叉算子，并采用基于Metropolis判别准则的复制算子，确保个体多样性和避免算法过早收敛．算例表明算法有效可行．     

考虑多路径选择的定制电动公交线路优化

为提高定制电动公交系统运营效率,本文探讨了考虑多路径选择的定制电动公交线路优化问题.首先,构建描述该问题的混合整数规划模型,以实现线路与路径的双重决策优化.模型以运营总收益最大化为目标,在约束中考虑定制电动公交特性,如车容量,乘客出行时间窗,续航里程,访问站点数等.其次,为求解模型,设计新的自适应大邻域搜索算法,提出相...     

Resource Partitioning and Routing Optimization in Relay Enhanced Cellular Network

A joint routing and resource partitioning scheme were proposed to improve cell capacity and user throughput of cellular network enhanced with two-hop fixed relay nodes (FRNs). Radio resources are partitioned under a reuse partitioning based framework, which guarantees effective and efficient inter-cell interference management. At the same time, each mobile terminal was assigned a channel-dependent route by the routing controller, which tries to maximize the cell capacity under the constraint imposed by reuse partitioning. Intensive computer simulations demonstrate the performance superiority of the FRN enhanced cellular network employing this scheme in comparison with conventional network, as well as the validity of the channel-dependent routing mechanism.     

求解带软时间窗的开放式车辆路径问题的遗传算法

通过应用交叉、变异概率的自适应机制和交叉算子A等技术,构造了一个求解带软时间窗的开放式车辆路径问题的遗传算法。用标准测试算例对算法进行测试,并将运算结果与文献中相关算法的运算结果相比较。结果表明,该算法具有较好的性能。     

The time-dependent pollution-routing problem

The Time-Dependent Pollution-Routing Problem (TDPRP) consists of routing a fleet of vehicles in order to serve a set of customers and determining the speeds on each leg of the routes. The cost function includes emissions and driver costs, taking into account traffic congestion which, at peak periods, significantly restricts vehicle speeds and increases emissions. We describe an integer linear programming formulation of the TDPRP and provide illustrative examples to motivate the problem and give insights about the tradeoffs it involves. We also provide an analytical characterization of the optimal solutions for a single-arc version of the problem, identifying conditions under which it is optimal to wait idly at certain locations in order to avoid congestion and to reduce the cost of emissions. Building on these analytical results we describe a novel departure time and speed optimization algorithm for the cases when the route is fixed. Finally, using benchmark instances, we present results on the computational performance of the proposed formulation and on the speed optimization procedure.     

基于地铁-货车联运的物流配送路径优化

为应对配送车辆引起道路拥堵和环境污染问题，提出地铁与货车联合运输. 在不改变地铁运行方案的前提下，利用地铁非高峰时段开展货物配送；考虑地铁剩余运能、货车容量、最大行驶距离、客户服务时间窗等限制条件，以配送距离最短为优化目标，构建基于地铁-货车联运的物流配送路径优化模型. 通过地铁配送路径设计不规则二维矩阵编码结构，使用改进自适应遗传算法求解. 以某市地铁货物运输为例，验证模型和算法的实用性、有效性. 结果表明，地铁-货车联合配送距离短，在客户时间窗范围内送达比例高，有效提高客户满意度.     

The value of real-time traffic information in urban freight distribution

Routes optimization in urban freight distribution is usually an off-line process based on the knowledge of historical conditions on the network. Real-time data provided by Intelligent Transportation Systems (ITSs) enable online re-optimization on the basis of actual traffic conditions.

?This paper evaluates the added value generated by re-optimizing the off-line solution with real-time information. The study is carried out for a practical application to the freight distribution of perishable goods in the city of Rome (Italy). The off-line problem is formulated as a vehicle routing problem with soft time windows while in the online problem it is also allowed to skip some customers or to re-sequence the deliveries. Both versions are solved with different algorithms and with different data sets. Results can be used to evaluate the potential return on investment on the acquisition of different kinds of traffic data. At the same time, results can be of interest for information providers, to fix the price of off-line and online information and/or to estimate the associated potential market share.     

STUDY ON NEIGHBORHOOD DISCOVERY PROTOCOL IN COMMUNICATION NETWORKS

IntroductionIt is well known thatthe PNNIsystem is a de-veloping system in the private ATM networkfield[1～ 5] .According to Ref.[6],PNNI includestwo categories of protocols,one defines for dis-tributing topology information between switchesand clusters of switches- routing protocol,and theother defines the signalling- signalling protocol,which is message flows used to establish point topoint and point to multi- point connections acrossthe ATM network.Forrealizing the PNNIroutingwith m…