Optimal Routing in a Small-World Network

Substantial research has been devoted to the modelling of the small-world phenomenon that arises in nature as well as human society. Earlier work has focused on the static properties of various small-world models. To examine the routing aspects, Kleinberg proposes a model based on a d-dimensional toroidal lattice with long-range links chosen at random according to the d-harmonic distribution. Kleinberg shows that, by using only local information, the greedy routing algorithm performs in O（lg^2 n） expected number of hops. We extend Kleinberg＇s small-world model by allowing each node x to have two more random links to nodes chosen uniformly and randomly within （lg n）2/d Manhattan distance from x. Based on this extended model, we then propose an oblivious algorithm that can route messages between any two nodes in O（lg n） expected number of hops. Our routing algorithm keeps only O（（lgn）β＋1） bits of information on each node, where 1 〈 β 〈 2, thus being scalable w.r.t, the network size. To our knowledge, our result is the first to achieve the optimal routing complexity while still keeping a poly-logarithmic number of bits of information stored on each node in the small-world networks.     

一种基于负载均衡的Ad Hoc网络接入Internet路由机制

在移动自组网(MANET)与Internet互联的网络结构中,由于移动节点的能量是影响网络性能的重要因素,因此必须考虑节点的负载及能量问题.本文针对这些问题提出一种基于负载均衡和不对称多径传输的路由机制LBAMR(Load-Balanced and Asymmetrical Multipath Routing),并用NS2软件对其进行了仿真.仿真结果表明,该路由机制能够有效地均衡网络负载并保护网络中的低能量节点,尽可能地延长网络寿命.     

改进遗传算法在多约束QoS动态组播路由选择中的实现

具有多约束QoS动态组播路由选择问题,实质上是一个NP完全问题.在参见文献[1-2]的基础上,提出了一种改进的遗传算法.在初始化群体阶段采用改进的深度优先搜索机制,克服了局部搜索能力差的缺点,在交叉、变异阶段采用类似罚值函数的方法,加快了收敛速度,同时用C 编程语言实现了遗传算法在多约束QoS动态组播路由选择问题.     

网络边布局技术研究综述

网络边布局技术是网络可视化研究的重要内容,良好的边布局能够有效地展示网络的整体结构并从中揭示出某些隐含的信息模式.为了全面地总结和分析现有网络边布局技术,首先归纳了网络边布局的主要任务,回顾了指导网络边布局的美学标准.然后将网络边布局技术归纳为3类:边路由技术、边融合技术和边集束技术,分别阐述了各类技术中典型布局方法的主要原理和特征,并重点对边集束技术进行了分类分析.最后总结了目前研究中还存在的一些问题,展望了网络边布局技术的发展前景和面临的挑战,以期为相关领域的研究者提供有益参考.     

A robust optimization approach for pollution routing problem with pickup and delivery under uncertainty

Organizations have recently become interested in applying new approaches to reduce fuel consumptions, aiming at decreasing green house gases emission due to their harmful effects on environment and human health; however, the large difference between practical and theoretical experiments grows the concern about significant changes in the transportation environment, including fuel consumptions, carbon dioxide (CO₂) emissions cost and vehicles velocity, that it encourages researchers to design a near-reality and robust pollution routing problem. This paper addresses a new time window pickup-delivery pollution routing problem (TWPDPRP) to deal with uncertain input data for the first time in the literature. For this purpose, a new mixed integer linear programming (MILP) approach is presented under uncertainty by taking green house emissions into consideration. The objective of the model is to minimize not only the travel distance and number of available vehicles along with the capacity and aggregated route duration restrictions but also the amount of fuel consumptions and green house emissions along with their total costs. Moreover, a robust counterpart of the MILP is introduced by applying the recent robust optimization theory. Computational results for several test problems indicate the capability and suitability of the presented MILP model in saving costs and reducing green house gases concurrently for the TWPDPRP problem. Finally, both deterministic and robust mathematical programming are compared and contrasted by a number of nominal and realizations under these test problems to judge the robustness of the solution achieved by the presented robust optimization model.     

基于惩罚因子的多约束剪枝QoS路由算法

为满足新一代互联网上各业务的服务质量( QoS)要求,设计一种多约束剪枝QoS路由算法PF-MCP,采用剪枝算法思想,综合考虑带宽、时延和抖动多重QoS约束,引入惩罚因子进行综合评价找出多条有效路径并从中选取最优路径。采用固定和随机网络层拓扑进行仿真实验,结果表明,与合成优先权值路由算法相比,PF-MCP算法在QoS满意度、服务节点计算能力及时间复杂度方面性能较优,具有路由运算量小、网络恢复能力强及选取的最优路径可信性高的特点,并且在覆盖网QoS路由方面适用范围广。     

可重构阵列自主容错方法研究

设计了一种具有故障自诊断和自修复能力的可重构阵列单元结构。在功能细胞单元内部实现分布式的故障自诊断,在测试到故障后,可以自主地将距故障单元最近的空闲单元进行替换,接着自动取消受故障影响的线网,并在新的布线端点间对这些线网重新布线。以4位并行乘法器为例,实验结果证明了可重构单元阵列的故障自修复能力,并验证其重构时间较短且可靠性较高。     

基于平均海明距离的WSN安全路由算法

提出一种基于平均海明距离的无线传感器网络安全路由算法。该算法利用节点的实时包传递率短序列和正常运行短序列之间的平均海明距离,检测节点是否正常。在节点中引入邻近节点表,对恶意节点进行隔离,在重新组簇的过程中节省节点能量,在路由选择时综合考虑能量、跳数和路径可靠性等因素。仿真实验结果表明,该算法能耗较低,具有较高的检测率。     

基于虫洞路由的无HoL阻塞环形架构

提出一种基于虫洞路由的无HoL阻塞环形片上互联网络架构,实现了在不消耗太多资源的前提下,用一级流水线以类虚拟输出队列的方式完全消除队头阻塞和死锁。评估不同参数下该环形架构的性能,与CELL EIB等环形实现相比,该架构以单数据包仅11周期最小延时的性能明显优于其他环形架构,同时最大吞吐率达到25.6 Gb/s。     

面向最小碳排放量的接送机场服务的车辆路径与调度

车辆路径与调度问题 (Vehicle routing and scheduling problem, VRSP)是制造系统自动化和商业服务系统优化调度要解决的重要问题, 常常以路径最短或成本(时间)最小为 优化目标. 在强制性碳排放政策的影响下, 如何通过路径优化与调度实现系统的节能减排, 已经成为管理者一个优化控制的目标. 本文 建立了针对接送机场服务中以最小碳排放量为目标的车次分配与调度问 题的0-1混合整数规划模型, 采用了改进的基于时间和地域划分的极线扫描算法. 重点通过不同类型、规模测试实例, 分别从测试实例的 顾客点位置分布、顾客规模以及车辆容量大小、满意度水平分析了对人均 碳排放的影响程度, 对现实接送机场服务运作中车辆配置和设置服务水平提供了有价值的建议.