Ad hoc网络中一种跨层流量分配算法——CLATA

针对ad hoc网络各协议层的功能都相互关联的特点,提出了一种在ad hoc网络中基于网络平均时延最小的跨层自适应流量分配算法（CLATA）。该算法将网络层自适应流量分配信息传递给媒体接入控制（MAC）层,以改进MAC层中的冲突退避算法,实现网络平均时延最小化,提高网络的利用率。仿真实验结果表明,该算法可以动态调整链路之间的流量,并具有快速的自适应性,优化网络资源的利用。     

基于混合拓扑的机械无线传感器网络多信道数据传输方法

针对机械振动无线传感器网络节点因信道带宽窄导致网络传输速率过低,在大量原始数据传输需求下实时性较差的问题,提出一种基于簇树星型混合拓扑的多信道数据传输方法。对各传感器网络节点进行树间通信干扰最小化信道分配,避免邻频干扰影响树间并行通信,在数据同步采集结束后,各节点以分配信道组建簇树星型混合拓扑网络进行数据传输;采用树间通信握手机制和树间通信优先级抢占机制解决簇树星型混合拓扑带来的树间互盲问题;将各采集节点短地址作为调度信息载入信标进行广播,各采集节点根据调度信息决定进行数据传输或者休眠,实现树内通信能耗最小化时序调度。将提出的多信道数据传输方法与载波侦听多路访问/冲突避免机制进行对比,实验结果表明该方法能有效提高机械振动无线传感器网络数据传输速率。     

基于边缘计算的软件定义云制造和柔性资源调度研究（英文）OA

本研究的重点是在云制造环境中实现快速重构、实现灵活的资源调度、开发资源潜力以应对各种变化。因此,本文首先提出了一种新的基于云和软件定义网络（SDN）的制造模型——软件定义云制造（SDCM）,该模型将控制逻辑从自动化硬件转移到软件上。这种转变意义重大,因为软件可以充当制造系统的“大脑”,并且可以轻松更改或更新以支持快速系统重新配置、运营和演进。随后,边缘计算被引入,以接近终端的计算和存储能力来补充云。另一个关键问题是管理由不同服务质量（QoS）要求的大量物联网（IoT）数据传输而导致的严重网络拥塞。基于SDCM的虚拟化和灵活的网络能力,本研究形式化了面向复杂制造任务集的时间敏感性数据流量控制问题,并考虑了子任务分配和数据路由路径选择。为了解决这一优化问题,提出了一种将遗传算法（GA）、Dijkstra最短路径算法和排队算法相结合的方法。实验结果表明,该方法能有效地防止网络拥塞,减少SDCM中的总通信延迟。     

ATM网络中VCC的实时动态路由调度的神经网络新方法

针对神经网络因其强并行处理能力极适用于ＡＴＭ网络实时动态路由调度,提出了一种基于Ｈｏｐｆｉｅｌｄ神经网络的新路由算法,该算法网络拓扑及链路长度参数仅仅与神经元偏置电流有关,使得其硬件实现及逻辑控制非常简单。仿真结果证明了这种新路由算法的自适应性和鲁棒性。     

A reliability-cost and Makespan driven fault-tolerant scheduling algorithm for distributed systems

为解决异构分布式环境下采用主副版本策略的可靠性调度问题,提出一种基于优先级约束的可靠性代价和Makespan(调度时长)驱动的分布式容错调度算法DRCAMD.该算法可在满足系统可调度性的前提下,以异构分布式环境的节点、通信链路的可靠性与Makespan做为可调节局部目标函数,实现具有较高可靠性及较短执行时间的容错调度策略,避免将任务分配到失效率较高的节点上执行.另外,算法的副版本采用被动和主副重叠方式执行,使得容错调度算法具有较大的灵活性.仿真实验表明,该算法性能优于现有容错算法.     

一种新型水下移动自组织网路由算法

目前针对移动自组织网提出的路由协议普遍存在路由发现和路由维护效率低的问题,在研究按需距离矢量(AODV)路由算法的基础上,提出了一种水下多路径选择按需距离向量算法(MAODV)。该算法采用多节点路由切换机制,在一条链路失效后不必重新启动路由发现过程,而选用备用节点构成新的链路,继续进行数据包的传输,大大节省了信息资源和带宽。计算机统计仿真表明,该MAODV方法的性能在端到端通信的平均时间延迟和数据包接收率上均优于(AODV)。有效地解决了路由协议中路由发现和路由维护效率低的问题。     

一种基于HLA/RTI的卫星组网仿真系统

设计了一种基于HLA/RTI的卫星组网仿真系统,在该系统中卫星节点、星间链路、卫星轨道和通信节点路由被划分为功能独立的联邦成员.这种结构具有良好的可扩展性,可适用于不同的卫星星座结构,同时可以适应不同的路由策略和各类空间通信链路模型.最后通过统计卫星组网网管报文响应时间验证了该仿真系统的可行性.卫星组网仿真系统为卫星组网的其他研究提供了仿真验证平台.     

基于列正交变换实现串行干扰消除的MIMO检测算法

针对用于多输入多输出（MIMO）通信系统检测的按序QR分解（SQRD）算法在多径瑞利慢衰落信道中检测误码率较高的不足,提出了一种基于列正交（CO）变换的串行干扰消除（SIC）算法——COSIC。该算法对信道矩阵按列正交变换,避免了求上三角矩阵的运算,并且在判决信号过程中,将先判决出的信号通过信道后的输出向量作为干扰进行消除,在略微增加系统时间复杂度的基础上,使系统检测性能得到了明显改善。在多散射物的无线通信环境下进行的仿真实验证实,与传统的SQRD算法相比,所提算法误码率显著下降．系统检测性能明显改善。     

一种用于MPLS光波长路由器的自适应路由策略

针对现有MPIS光波长路由器存在IP层和光层分别路由的不足,提出了一种使用了联合路由算法的自适应路由策略,该路由策略可以适应流量疏导端口资源的变化,合理利用波长和流量疏导端口,提高网络性能和资源利用率。同时为了支持该路由策略,还提出了一种辅助拓扑的构造方法。仿真结果显示,该自适应路由策略具有更好的性能,可以承载更多的业务。     

域间流量工程技术研究

为减少Internet域间路由协议按策略进行最优路径选择时可能引起的ISP（Internet Service Provider）域内链路拥塞,本文深入分析了不同方法的优缺点,提出基于粒子群的优化算法,为有效实施域间流量工程详细算法设计提供解决方法。     

一种通过优化链路权值来增强网络生存性的方案

提出了一种通过优化链路权值来增强网络生存性的方案.该方案在选择链路权值时考虑了所有可能的链路故障情景和网络流量的变化,通过引入费用函数对过载链路赋以高费用的方法来避免链路过载,并利用遗传算法在所有可能的链路权值组合中寻找使链路费用之和最小的组合.实验结果表明通过该方案求得的权值组合,能够使网络在出现流量变化和链路故障时有效避免链路拥塞,从而增强网络的生存性.     

An Efficient Algorithm for Global Path Optimization in MPLS Networks

This paper proposes an algorithm to solve the optimization of label switched paths (LSPs) in multiprotocol label switching (MPLS) networks. The underlying optimization problem in this task is the well-known unsplittable multicommodity flow problem equipped with practically relevant objective functions and specialized with hard technical requirements.The proposed heuristic algorithm is based on network flow theory. It incorporates iterative shortest path search and performs adaptive edge weight adjustments in order to successfully satisfy all the required traffic demands and to maximize user-defined objectives. The robust algorithm facilitates the incorporation of several strategic and optimization objectives and the fulfillment of certain hard technical requirements of the target problem domain as well. Novel features of the approach include a new adaptive path allocation/deallocation strategy based on the identification of bottleneck links, demand ordering and preprocessing phases, and a systematic path allocation control method.The efficiency of the method is empirically shown on randomly generated networks with practical sizes and topologies, and on a real-world IP (Internet Protocol) backbone network. The algorithm is able to successfully solve difficult problem instances comprising very large instances with 1000 nodes, 3500 edges and 999000 traffic demands. The computational tests demonstrate that the proposed approach can be efficiently applied to solve problem instances that embed MPLS specific hard technical requirements. Furthermore, it is shown that our algorithm offers significantly better performance than the straightforward adaptations of existing methods that were developed for related network optimization problems. Namely, our algorithm produces acceptable results quicker, it can solve problems that were not previously solvable, and it yields better results than the alternative methods. The extensive empirical tests demonstrate the combinatorial properties of the target problem and the performance aspects of the algorithm and its components as well.     

Intelligent infrastructure-based queue-end warning system for avoiding rear impacts

Accident avoidance is a very important part of enhancing road safety. The development of a queue-end warning system for highway work zones which automatically predicts queue-end location and alerts drivers so that rear-end collisions can be avoided has been described. In the absence of the widespread use of in-vehicle collision warning devices, dynamic messages about queue-end, displayed on portable variable message sign (PVMS) boards, are necessary for improving road safety. Although queues at selected locations along the road can be detected by the simple use of sensors, the changing nature of queue length would require numerous sensors to find the end of traffic queue. The reported queue-end warning system is based on a combination of sensors for detecting traffic and an artificial neural network (ANN) model-based algorithm for predicting queue-end location and issuing warning messages displayed on PVMS. Following the characterisation of work zones in terms of functional areas and geometrics, a microsimulator was calibrated and validated. Simulations were carried out next with traffic sensors and queue counter looped-in and the resulting data were used for training and validation of ANN models for queue length prediction. An automated information system was synthesised that integrates traffic sensors, ANN models, PVMS and potential links with other media. Selected results of ANN models illustrate their application in the queue-end warning system     

Load balancing in the provisioning of hose model virtual private networks with multi-path routing

Load balancing in the provisioning of virtual private network (VPN) service in the hose model is studied. Single-path routing and tree routing for the hose model tend to aggregate bandwidth reservations on a small number of links, thus leading to congestion problems in service provider networks. If the link capacity is depleted as a result of improper routing, all future non-VPN traffic will be blocked. We propose a novel multi-objective multi-path (MOMP) routing linear program with the maximum fraction of traffic on a path (MFTP) constraint to solve the problem. The MOMP routing algorithm is able to reduce the bandwidth reservation on the most loaded link by as much as 50%, thus effectively alleviating the potential congestion problems in service provider network. The MFTP constraint provides a guarantee of the availability of multiple paths for each VPN endpoint pair. Further reduction of the bandwidth reservation can be achieved depending on the MFTP value. This is highly significant.     

Turning-lane and signal optimization at intersections with multiple objectives

Traffic congestion at intersections is a serious problem in cities. In order to discharge turning vehicles efficiently at intersections to relieve traffic jams, multiple left-turn and right-turn lanes are often used. This article proposes a novel multi-objective optimization method for signal setting and multiple turning-lane assignment at intersections based on microscopic traffic simulations and a cell-mapping method. Vehicle conflicts and pedestrian interference are considered. The intersection multi-objective optimization problem (MOP) is formulated. The cell-mapping method is adopted to solve the MOP. Three measures of traffic performance are studied including transportation efficiency, energy consumption and road safety. The influence of turning-lane assignment on intersection performance is investigated in the optimization. Significant impacts of the number of turning lanes on the traffic are observed. An algorithm is proposed to assist traffic engineers to select and implement the optimal designs. In general, more turning lanes help increase turning traffic efficiency and lower fuel consumption in most cases. Remarkable improvement in traffic performance can be achieved with combined optimization of lane assignment and signal setting, which cannot be obtained with signal setting optimization alone. The studies reported in this article provide general guidance for intersection planning and operation. The proposed optimization methodology represents a promising emerging technology for traffic applications.     

基于"边折叠"的可逆累进网格生成算法的研究

在分析已有累进网格生成算法的基础上,提出一种基于“边折叠”网格化简方法的累进网格生成算法,构造了累进网格的表示新方法。算法消除了累进网格技术中的二义性,具有支持多种网格类型、保持相邻层次细节模型间的平滑过渡等特点。实验表明,算法具有有效性和可靠性。     

A distinctive approach to obtain higher page rank through search engine optimization

Search engine optimization (SEO) pertains to the activity of optimizing individual websites and webpages to get higher page rank in the search results. Websites are ordinarily optimized through back links, while individual webpages are optimized through specific keywords. In this paper, we propose a framework based on set of guidelines for keyword research analysis and back links generation. The proposed framework suggests that webpage content should be based on keywords and the site traffic should be monitored through referrals. We argue that if a website has some prevalent and pertinent keywords in its content and title along with a reasonable amount of back links that help watch the website traffic, then we can get better rank for the website in the search results. The framework also emphasizes that proper keyword selection and link building should be taken into account when developers and designers work on a software development project. The results of the study are reported here.     

An Active Queue Management Algorithm： CRED

By applying the method of average and variance, a new queue management algorithm named the Classified-Random Early Detection （CRED） algorithm is presented which can identify the media streaming, TCP traffic and other UDP traffic at the edge routers. The algorithm discriminates the slow start and the congestion control phase of the TCP traffic and combines the TCP congestion control with the IP congestion control to alleviate the congestion effectively. Simulation shows that CRED can not only make the media streaming obtain the resources needed but also protect the TCP traffic transmitted effectively and reliably.     

Accident prediction models for urban roads

This paper describes some of the main findings from two separate studies on accident prediction models for urban junctions and urban road links described in [Uheldsmodel for bygader-Del1: Modeller for 3-og 4-benede kryds. Notat 22, The Danish Road Directorate, 1995; Uheldsmodel for bygader- Del2: Modeller for straekninger. Notat 59, The Danish Road Directorate, 1998] (Greibe and Hemdorff, 1995, 1988).The main objective for the studies was to establish simple, practicable accident models that can predict the expected number of accidents at urban junctions and road links as accurately as possible. The models can be used to identify factors affecting road safety and in relation to 'black spot' identification and network safety analysis undertaken by local road authorities.The accident prediction models are based on data from 1036 junctions and 142 km road links in urban areas. Generalised linear modelling techniques were used to relate accident frequencies to explanatory variables.The estimated accident prediction models for road links were capable of describing more than 60% of the systematic variation ('percentage-explained' value) while the models for junctions had lower values. This indicates that modelling accidents for road links is less complicated than for junctions, probably due to a more uniform accident pattern and a simpler traffic flow exposure or due to lack of adequate explanatory variables for junctions.Explanatory variables describing road design and road geometry proved to be significant for road link models but less important in junction models. The most powerful variable for all models was motor vehicle traffic flow.     

A bi-objective optimization approach for exclusive bus lane selection and scheduling design

This study proposes a methodology to solve the integrated problems of selection and scheduling of the exclusive bus lane. The selection problem intends to determine which roads (links) should have a lane reserved for buses while the scheduling problem intends to find the time period of the application. It is formulated as a bi-objective optimization model that aims to minimize the total travel time of non-bus traffic and buses simultaneously. The proposed model formulation is solved by the hybrid non-dominated sorting genetic algorithm with Paramics. The results show that the proposed methodology is workable. Sets of Pareto solutions are obtained indicating that a trade-off between buses and non-bus traffic for the improvement of the bus transit system is necessary when the exclusive bus lane is applied. This allows the engineer to choose the best solutions that could balance the performance of both modes in a multimode transport system environment to achieve a sustainable transport system.