Distributed stochastic multi-vehicle routing in the Euclidean plane with no communications

This paper presents an algorithm for the multi-vehicle routing problem with no communications among the vehicles. The scenario consists in a convex Euclidean mission space, where targets are generated according to a Poisson distribution in time and to a generic continuous spatial distribution. The targets must be visited by the vehicles, which, therefore, must act in coordination. Even if no communications are required, the proposed routing strategy succeeds in effectively partitioning the mission space among the vehicles: at low target generation rates, the algorithm leads to the well-known centroidal Voronoi tessellation, whereas at high target generation rates, simulation results show that it has better performances with respect to a reference algorithm with no communications among vehicles.     

Dynamic routing strategies for JIT production in hybrid flow shops

In production processes, just-in-time (JIT) completion of jobs helps reduce both the inventory and late delivery of finished products. Previous research which aims to achieve JIT job completion mainly worked on static scheduling problems, in which all jobs are available from time zero or the available time of each job is known beforehand. In contrast, dynamic scheduling problems which involve continual arrival of new jobs are not much researched and dispatching rules remain the most frequently used method for such problems. However, dispatching rules are not high-performing for the JIT objective. This study proposes several routing strategies which can help dispatching rules realize JIT completion for jobs arriving dynamically in hybrid flow shops. The routing strategies are based on distributed computing which makes realtime forecast of completion times of unfinished jobs. The advantages include short computing time, quick response and robustness against disturbance. Computer simulations show that the performance of dispatching rules combined with the proposed routing strategies is significantly higher than that of dispatching rules only and that of dispatching rules combined with the previous routing methods.     

Applying intelligent agents technology in a collaborative work environment

The current state of the art in computer–mediated collaborative work is mainly limited by the fairly primitive discourse structures that most asynchronous conference systems implemented so far provide and because they lack consensus seeking and problem solving abilities. To address these issues, we first propose a refined model of the discourse acts met in a collaborative work environment. In the sequel, using this model in the context of an already implemented system, we apply intelligent agents technology in order to enhance and facilitate collaborative work. The overall approach combines concepts from the AI and CSCW disciplines, while aims at giving a highly active role to the participants involved in such environments.     

仿真技术在电话网路由选择中的应用

路由策略对电话网的服务质量有重要的影响,应用电话网真实服务过程模型,分析了电话网路由选择方法,定量评估了不同的路由策略对网络服务质量的影响,为电话网路由策略的选择提供了依据。     

On reactive routing protocols in ZigBee wireless sensor networks

ZigBee is the primary standard solution for wireless sensor networks, implementing the Ad hoc On‐Demand Distance Vector (AODV) protocol in the network layer and supported by the standard IEEE 802.15.4. This study is focused on mesh topologies and the critical problems encountered when AODV is executed in conjunction with the Carrier Sense Multiple Access with Collision Avoidance protocol. These problems are mainly related to the packet overhead required to carry out route creation. To perform preliminary experiments to be able to implement AODV in a real network, a new metric is proposed herein. This metric uses fuzzy logic to help in the decision‐making process. The objective of the fuzzy routine is to determine, during the route‐discovery process, the best node to forward request/reply packets, with the aim of reducing packet overhead and energy consumption. Moreover, minor changes are also added to the discovery procedure of AODV to improve the performance of the route‐creation process. This intelligent version of AODV has provided promising experimental results, greatly reducing the number of packets required, with the consequent energy saving while selecting the best nodes to be part of the routes.     

基于改进ACO与分布式社区检测的WSN路由协议

在无线传感器网络（WSN）的研究中,兼顾能量消耗和数据传输的可靠性是个非常棘手的问题。基于此,将改进蚁群优化的元启发式算法与复杂度低的分布式社群检测的标签传播技术相结合,提出了一种基于改进蚁群优化算法与分布式社区检测的WSN路由协议,新的路由协议在WSN中创建社群,并通过群集智能在社区内传送数据,从而实现能量消耗的平衡,它在构建和维护路由路径时具有较低的内存开销。此外,新的路由协议通过基于数据转发策略中社群之间的确认机制实现数据传输的高可靠性。仿真结果表明,路由协议在实际吞吐量、能量消耗等方面具有明显的优势。     

无线Mesh网络中一种分布式路由方案

在多射频多信道无线Mesh网络中,链路负载和节点位置的变化将导致网络性能的下降。针对此问题,在混合无线网状路由协议反应式路由基础上,设计了一种新的混合信道分配的分布式路由算法。该算法在路由建立的同时可实现以数据流为单位的最优信道分配,且能避免因单节点失效导致整个网络崩溃的危险。仿真结果表明,提出的RHCA算法较传统算法在网络吞吐量和端到端平均时延方面均有显著优势。另外,在节点移动场景下,所提出的分布式路由算法较其他方法能获得更高的吞吐量和更好的稳健性。     

On the formulation of competitive negotiations in Web applications: The Latin-American market case

Work on electronic negotiation has motivated the development of systems with strategies specifically designed to establish protocols for buying and selling goods on the Web. On the one hand, there are systems where agents interact with users through dialogues and animations, helping them to find products while learning from their preferences to plan future transactions. On the other hand, there are systems that employ knowledge-bases to determine the context of the interactions and to define the boundaries inherently established by the e-Commerce. This paper introduces the idea of developing an agent with both capabilities: negotiation and interaction in an e-Commerce application via virtual reality (with a view to apply it in the Latin-American market, where both the technological gap and an inappropriate approach to motivate electronic transactions are important factors). We address these issues by presenting a negotiation strategy that allows the interaction between an intelligent agent and a human consumer with Latin-American idiosyncrasy and by including a graphical agent to assist the user on a virtual basis. We think this may reduce the impact of the gap created by this new technology.     

一种无线自组网均匀分布簇结构路由

在低能量自适应簇结构层次(lowenergy adaptive clustering hierarchy,LEACH)路由协议的基础上,提出了一种均匀的分布式簇结构层次路由协议。该协议将路由过程分为三个步骤,按照能量均衡的原则选取簇头节点,各节点能够分布式地自主决定该节点的状态。仿真结果显示,该协议拥有比LEACH更低的能量消耗和更长的网络生命周期。     

Study on the algorithm for smart community sensor network routing with adaptive optimization via cluster head election

To reduce the uneven energy consumption for the data transmission and extend network life of intelligent community sensor network, an adaptive routing optimized algorithm for intelligent community sensor networks with cluster head election is proposed. In this algorithm, a three-dimensional clustering method adapted to the structure of intelligent community sensor network is proposed. The three-dimensional clustering method uses the cluster head election mechanism based on minimizing the total transmission loss to optimize the energy of the intelligent community sensor network. Second, an adaptive ant colony propagation method is proposed to solve the problem of intercluster data propagation after clustering. With the best path finding algorithm of ant colony algorithm, energy balance routing with lower energy loss and lower packet error rate is proposed. Finally, the simulation results show that the algorithm has better performance in reducing energy consumption and delay, improving transmission efficiency and node survival time.     

农村公交协同车辆路径问题的研究

针对考虑农村人口出行频次的季节偏好性、早晚高峰期班次多、乘客乘车的最长忍受时间、司机连续驾驶时间限制、车辆可以停在其他车场、车场与车场之间的车辆可以共享等因素的农村公交的协同车辆路径问题,建立车辆租赁模式的单车型开放式协同车辆路径问题的数学模型.结合节约算法、扫描算法和遗传算法,构造混合蚁群算法对实例进行仿真.首先通过扫描算法对站点进行分组,然后应用节约算法对单个旅行商问题(traveling salesman problem,TSP)求解得到可行解,最后应用混合蚁群算法对可行解进一步优化.结果表明该算法在收敛速度和寻优能力两方面都优于遗传算法.     

Coordinated circumnavigation by multiple agents under directed topology

ABSTRACT

This paper focuses on the coordinated circumnavigation problem for multiple agents with directed communication topology. All agents are required to be evenly spaced around a moving target, and orbit around it with prescribed radii and circular velocity. We divide the coordinated circumnavigation system into a cascaded system consisting of a standoff tracking subsystem and a spacing distribution subsystem. A tracking controller and an additional controller for the two subsystems are developed, respectively. The global uniform stability of the coordinated circumnavigation system is analysed using the cascaded control theory. The presented controllers render each individual agent circumnavigating the target with the desired requirements. More importantly, we show that the derived tracking controller is a general extension of existing controllers for single agent circumnavigation problem. Another feature of the proposed controllers is that the directed topology considered only needs to have a directed spanning tree. Furthermore, the proposed controllers take the velocity constraints into consideration, that is more rational for practical applications. Numerical simulations are provided to verify the effectiveness of the proposed methods.     

Simulation of congestion avoidance and routing in packet switching networks

The development of a flexible computer simulation package for packet switching computer networks that enables the evaluation of different congestion avoidance methods and routing strategies is discussed. The package is presented in terms of the factors involved, the operations required, and the simulation execution considerations. Use of the package for the evaluation of congestion avoidance methods and routing strategies is described. The congestion avoidance methods considered include isarithmic methods with static and dynamic control. In addition, static and dynamic routing strategies are taken into account. The relative differences between the various methods and strategies considered are presented. It has been found that the results obtained agree with previous results, and this confirms the suitability of the package for future investigation. The package would be useful to students and researchers in the field, especially since it uses the widely known computer language Pascal, and is run on an IBM PC(AT).     

光网络环境中最先开始路径优先的自适应路由算法

为了优化光网络环境下分布式计算系统的资源调度性能,提出了一种最先开始路径优先的自适应路由算法。该算法基于Dijkstra最短路径优先算法,通过引入一个时间标记变量来估计从源节点到当前目标节点的最先可用时间,绕过调度过程中产生拥堵的链路,选择能够最先开始通信的路由,从而减小通信竞争冲突,缩短了调度长度。仿真结果表明,该算法能够使用较少的网络链路资源来获得最短的调度长度。     

发布订阅系统在移动Ad Hoc网络中的三种路由算法

介绍了分布式发布/订阅系统的原型，为Ad Hoc网络中的发布/订阅系统设计了三种基于内容的路由算法，分别说明了它们的运行方式，并进行了仿真与比较。结果表明：基于内容的可靠容错路由算法能够100%保证信息的传输，有容错机制，可靠性较强，但出现了传输延迟；基于内容的路由算法的可靠性不强，适合有线网络中分布式发布订阅系统的信息传输，传输延迟小；基于内容的容错路由算法有容错机制，传输延迟小     

自动信任协商中一种最小信任披露策略

自动信任协商是通过逐渐请求和披露数字证书在两个陌生实体间建立相互信任的方法。当前对自动信任协商协商策略的研究,往往存在很多问题。文章提出了一种基于期望因子的自动信任协商模型,该模型采用MCD策略,通过分析各信任证书的期望因子,当可能的协商存在时,它能披露和请求最小的信任证找到一条成功的协商路径,当协商不可能成功时,尽快的发现并终止它。它能保证在协商的过程中没有不相关的信任证被披露并且不需要暴露双方的访问控制策略,同时通过实验证了明MCD策略是完备的。     

WSNs中一种基于EIETX的自适应功率控制的机会路由

为了延长无线传感器网络(WSNs)的生存时间,提出了一种基于EIETX的自适应功率控制的机会路由协议APExOR。考虑节点剩余能量,改进了IETX,给出基于EIETX的转发候选集选择策略;分析节点间链路状况,建立起相关的转发能效模型,提出了一种自适应优化转发候选集和发射功率的算法;利用以上策略和算法改进ExOR协议,提出了适合WSNs的APExOR协议。仿真实验表明:与固定功率下的ExOR协议相比,APExOR协议提高了网络吞吐量,降低了网络的能量消耗。     

现场总线系统分布式智能预测控制的实现

对于采用现场总线系统控制的复杂对象，应用智能预测控制的方式对其进行分布式控制，将现场总线的特点与智能预测控制方法相结合，使各子系统之间的参数以及控制动作协调一致，以实现对整个系统的优化控制．提出了在现场总线系统中构建该方法的步骤，并给出了一个采用该控制方法获得较好控制效果的具体实例。     

Artificial intelligence heuristics in solving vehicle routing problems with time window constraints

This paper describes the authors’ research on various heuristics in solving vehicle routing problem with time window constraints (VRPTW) to near optimal solutions. VRPTW is NP-hard problem and best solved to near optimum by heuristics. In the vehicle routing problem, a set of geographically dispersed customers with known demands and predefined time windows are to be served by a fleet of vehicles with limited capacity. The optimized routines for each vehicle are scheduled as to achieve the minimal total cost without violating the capacity and time window constraints. In this paper, we explore different hybridizations of artificial intelligence based techniques including simulated annealing, tabu search and genetic algorithm for better performance in VRPTW. All the implemented hybrid heuristics are applied to solve the Solomon's 56 VRPTW with 100-customer instances, and yield 23 solutions competitive to the best solutions published in literature according to the authors’ best knowledge.     

认知无线Mesh网络信道接入与路由协议研究*

针对认知用户可用频谱动态变化,数据链路由于无可用的授权信道而无法建立,导致路径中断的问题,引入了具有拥塞感知能力的多径路由协议。认知用户可通过在多条路径中选择具有SOP交集的下一跳节点进行通信,降低主用户在授权信道上出现对认知用户数据传输带来的干扰;并在路由协议中采用了拥塞控制技术,通过对节点的拥塞情况进行感知,可有效避免瓶颈节点的出现。仿真结果表明,该协议在认知无线Mesh网络中,能较好地减小端到端延迟,提高数据包的成功投递率,增加网络的整体吞吐量。