An efficient variable neighborhood search heuristic for very large scale vehicle routing problems

In this paper, we present an efficient variable neighborhood search heuristic for the capacitated vehicle routing problem. The objective is to design least cost routes for a fleet of identically capacitated vehicles to service geographically scattered customers with known demands. The variable neighborhood search procedure is used to guide a set of standard improvement heuristics. In addition, a strategy reminiscent of the guided local search metaheuristic is used to help escape local minima. The developed solution method is specifically aimed at solving very large scale real-life vehicle routing problems. To speed up the method and cut down memory usage, new implementation concepts are used. Computational experiments on 32 existing large scale benchmarks, as well as on 20 new very large scale problem instances, demonstrate that the proposed method is fast, competitive and able to find high-quality solutions for problem instances with up to 20,000 customers within reasonable CPU times.     

无线传感器网络安全技术综述

详细阐述了传感器网络安全现状、面临的安全挑战及其需要解决的安全问题。从密钥管理、安全路由、认证、入侵检测、DoS攻击、访问控制方面讨论传感器网络的各种安全技术，并进行综合对比。希望通过这些说明和对比，能够帮助研究者为特定传感器网络应用环境选择和设计安全解决方案。最后总结和讨论传感器网络安全技术的研究方向。     

Ad Hoc网络跨层仿真技术研究

Ad Hoc网络是一种特殊、新型且应用前景广阔的移动无线网络,其发展非常迅速,这也为其网络验证和分析带来了挑战。网络仿真是目前研究Ad Hoc网络协议和算法的一种非常有效的手段。介绍了Ad Hoc网络的体系结构,并对网络仿真建模技术进行了探讨,在此基础上,提出了Ad Hoc网络的跨层仿真方案,以及网络仿真过程及如何进行仿真性能分析。     

物流车辆路径问题的混合快速蚂蚁算法

通过分析快速蚂蚁算法的原理和易陷入局部最优的缺点,提出了将贪婪算法和快速蚂蚁算法相结合的混合算法求解物流车辆路径问题.混合算法在最优值未改进次数超过限定次数时,自动调用贪婪算法来寻找一个局部最优解,并调整相应路径上信息素的量.为保证解的多样性,对贪婪算法本身使用随机选择第一个客户的方法进行了调整.用计算实例比较并分析了快速蚂蚁算法、混合算法及其他算法应用到车辆路径问题上的结果,说明了贪婪算法使混合算法跳出局部最优的过程以及混合算法的不足之处.     

基于人工免疫-蚁群算法的平面QoS路由模型

人工免疫算法具有快速随机的全局搜索能力,但系统中的反馈信息利用不足且有大量无为的冗余迭代。蚁群算法具有分布式并行全局搜索能力,但初期信息素匮乏。本文提出一种基于人工免疫-蚁群算法的混合算法,采用人工免疫算法生成信息素分布,利用蚁群算法求优化解。将该算法用于求解包含带宽、时延和最小代价约束条件在内的平面QoS路由模型问题,进行计算机仿真。结果表明,该算法是一种收敛速度和寻优能力都比较好的优化方法。     

无线传感器网络SPINS安全协议分析与改进

针对传感器网络不仅有更多的攻击方式,而且可以采用的防御手段也极为有限的问题,文章从安全协议的设计角度出发阐述了无线传感器网络存在的安全问题并有针对性地提出了解决方法。在详细分析SPINS[1]协议安全特性的基础上指出了该协议尚存的安全问题,并对协议进行了有效的改进。     

Non-interactive key establishment in mobile ad hoc networks

We present a new non-interactive key agreement and progression (NIKAP) scheme for mobile ad hoc networks (MANETs), which does not require an on-line centralized authority, can non-interactively establish and update pairwise keys between nodes, is configurable to operate synchronously or asynchronously, and supports differentiated security services w.r.t. the given security policies. NIKAP is valuable to scenarios where pairwise keys are desired to be established without explicit negotiation over insecure channels, and also need to be updated frequently.     

A resource-efficient and scalable wireless mesh routing protocol

By binding logic addresses to the network topology, routing can be carried out without going through route discovery. This eliminates the initial route discovery latency, saves storage space otherwise needed for routing table, and reduces the communication overhead and energy consumption. In this paper, an adaptive block addressing (ABA) scheme is first introduced for logic address assignment as well as network auto-configuration purpose. The scheme takes into account the actual network topology and thus is fully topology-adaptive. Then a distributed link state (DLS) scheme is further proposed and put on top of the block addressing scheme to improve the quality of routes, in terms of hop count or other routing cost metrics used, robustness, and load balancing. The network topology reflected in logic addresses is used as a guideline to tell towards which direction (rather than next hop) a packet should be relayed. The next hop is derived from each relaying node’s local link state table. The routing scheme, named as topology-guided DLS (TDLS) as a whole, scales well with regard to various performance metrics. The ability of TDLS to provide multiple paths also precludes the need for explicit route repair, which is the most complicated part in many wireless routing protocols. While this paper targets low rate wireless mesh personal area networks (LR-WMPANs), including wireless mesh sensor networks (WMSNs), the TDLS itself is a general scheme and can be applied to other non-mobile wireless mesh networks.     

中国AS级互联网网络拓扑现状分析

本文介绍了中美两个AS级路由导出观察系统Route Views 和 BGPView.特别对中国互联网网络拓扑现状通过采集大量自治系统(AS)间的BGP(Border Gateway Protocol)路由信息,进行统计分析,提出发展建议.并对改进数据观察和分析系统进行了探讨.     

On-Demand Utility-Based Power Control Routing for Energy-Aware Optimization in Mobile Ad Hoc Networks

In this paper, we propose a novel on-demand energy-aware routing protocol, UBPCR [utility-based power control routing], which reduces the trade-offs that arise in the other energy-aware route selection mechanisms that have recently been proposed for mobile ad hoc networks. Our approach is based on an economic framework that represents the degree of link's satisfaction (utility). With UBPCR, the utility function for any transmitter-receiver pair is defined as a measure of the link's preference regarding the signal-to-interference-and-noise ratio (SINR), the transmit power, and the transmitter's residual battery capacity. During a route-searching process, each intermediate node between the source and the destination is executed via two consecutive phases: the scheduling phase and the transmit power control phase. The scheduling algorithm finds the proper qualified data slot for the receiving channel so that the transmissions of independent transmitters can be coordinated. The transmit power control determines the optimal power, if one exists, that maximizes the corresponding link's utility. Extensive simulations show that the UBPCR protocol can achieve incompatible goals simultaneously and fairly. Chan-Ho Min received the B.S. degree in Industrial Management and the M.S. degree in Industrial Engineering from Korea Advanced Institute of Science and Technology (KAIST) in 2000 and 2002, respectively, where he is currently pursuing the doctoral degree in Industrial Engineering (Telecommunication Engineering Interdisciplinary Program) at KAIST. His research interests include the optimization problems of radio resource management for broadband wireless/cellular/ad hoc/satellite communication networks. In particular, he focuses on mobile ad hoc networking. Sehun Kim received the B.S. degree in Physics from Seoul National University, Seoul, Korea, and the M.S .and Ph.D. degrees in Operations Research from Stanford University. In 1982, he joined the faculty of the Korea Advanced Institute of Science and Technology (KAIST), where he is currently a Professor of Industrial Engineering. His research has been in the areas of combinatorial and nonlinear optimization. Recently, he is working on the application of optimization techniques to the design and analysis of computer and communication systems. He has published a number of papers in Mathematical Programming, Operations Research Letters, Journal of Optimization Theory and Applications, IEEE Trans. on Vehicular Technology, and International Journal of Satellite Communications.