大规模高速网络流量工程研究

主要讨论互联网主干上的流量工程。由于现在路由协议使网络的低效率和新的应用的出现，迫切要求发展新的技术、引进流量工程的观点来处理这些问题。介绍了MPLS等的新的IP交换技术及其相关的路由算法；讨论了在IP主干上电话传输技术。     

高速公路宏观动态交通流模型的FPGA仿真实现

高速公路宏观动态模型研究对高速公路交通流的控制具有重要意义。以工控机为处理核心的系统存在的体积大、功耗大,不适宜长期在实际路口工作的缺陷,本文旨在研究一种基于FPGA的仿真实现高速公路宏观动态模型,以克服工控机的不足之处。设计了16位自定义浮点数,与Quartus II软件中公开浮点数运算IP核相比,能够在保证计算精度的前提下节省FPGA的逻辑资源。基于上述浮点数运算模块,本文对高速公路宏观动态交通流模型进行了FPGA的仿真实现,并将其结果与MATLAB运算结果进行对比。结果表明基于FPGA的仿真不仅能够满足仿真精度的指标,还可以获得更快的运算速度。     

交通事故警示装置

为了解决汽车连环追尾的恶性交通事故,给人们的生命财产造成重大损失的问题.本文设计实现了一种利用ATmega128单片机与Zigbee无线传输模块组成的交通事故警示装置.该装置采用ZigBee无线通信技术,通过星形网络实现主从节点的数据采集和传输,并详细阐述了ZIgBee中心节点和终端节点的软硬件设计.实际应用表明,该系统具有操作简便、安全可靠等特点,达到了设计要求.     

A new model for network traffic forecast based on user's mobility in cellular networks with highway stretches

Wireless communications have always faced the scarceness of bandwidth and until today the cellular division has solved this problem by making radio cells always smaller. However, as cell size is reduced, more users will probably require handoffs, and signaling can overload the system. Further, the decrease in cell dimension cannot ensure the best utilization of system resources, because user density in the cell is not constant over the time. Dynamic allocation might be the solution, but it is a complex task, basically due to complexity of the models for the mobility prediction, especially in those environments where users move very fast (e.g. highways). This last one is a typical environment where high mobility of vehicles does not allow small cell sizes and thus system capacity is intrinsically bounded. In this paper, we deploy an analytical model for a cellular network operating in a high mobility environment. Such a model is capable of representing and forecasting wireless system evolution in terms of channel occupancy, starting from the current state of the mobile network and road traffic. This model has been defined by integrating a vehicular traffic model with a wireless cellular communication one. With such approach the dynamic behaviour of the most critical mobile terminals, those associated with vehicles, are described in a very precise and specific way with respect to mobility. Many results obtained with specific simulation tools and herein reported show the good behaviour of our proposal. Copyright © 2004 John Wiley & Sons, Ltd.     

基于单目视觉的行车环境安全预警系统设计

文中设计了基于机器视觉的行车环境安全预警系统,采用包含视频图像采集、行车环境检测以及行车环境安全预警3个功能模块的系统结构,重点研究并提出了新的行车环境识别方法,包含车道线提取和前方车辆检测方法,并对系统硬件架构及软件流程和算法进行说明,实现高速公路行车环境的识别并进行危险警示。实验结果显示,系统能够准确地对前方车道线和车辆进行检测,实现设计效果。     

GeoVisual analytics for understanding the distribution of speeding patterns on arterial roads: assessing the traffic safety of vulnerable road users

ABSTRACT

Arterial roads have operational significance and play a substantial role in the mobility of modern society. They make up the majority of road network in urban and rural areas and allow high-speed movement despite traffic-controlling elements. In densely populated areas where the presence of Vulnerable Road Users (VRUs) is high, high-speed movement is problematic, and speed calming measures are needed to improve traffic safety, since many VRUs do crossroads, regardless of the road network regulations. These aspects have been researched in the traffic domain in a small scale, and not much has been investigated from a visualisation perspective. To provide comprehensive insights on the movement characteristics of arterial roads, we propose a GeoVisual Analytics (GVA) approach. GVA techniques are suitable solutions to display and extract knowledge from large amounts of Floating Car Data (FCD) collected through on-board devices of vehicles. By cross-sector collaboration between cartographic and traffic experts, five arterial road segments in Aalborg City were selected to answer where and when in particular VRUs do cross streets by ignoring traffic rules. Based on clusters of large unexplainable deviations from driving speed in FCD, the results uncovered meaningful patterns from complex traffic movements. They also allowed for the provision of some recommendations that are critical for traffic safety in urban areas.     

Research of the traffic characteristics for the real time online traffic classification

Aiming at the hysteretic characteristics of classification problem existed in current internet traffic identification field,this paper investigates the traffic characteristic suitable for the on-line traffic classification,such as quality of service (QoS).By the theoretical analysis and the experimental observation,two characteristics (the ACK-Len ab and ACK-Len ba) were obtained.They are the data volume which first be sent by the communication parties continuously.For these two characteristics only depend on data’s total length of the first few packets on the flow,network traffic can be classified in the early time when the flow arrived.The experiment based on decision tree C4.5 algorithm,with above 97% accuracy.The result indicated that the characteristics proposed can commendably reflect behavior patterns of the network application,although they are simple.     

WMN-based city traffic information acquisition system

Traffic information acquisition system is an essential part of the intelligent transportation system (ITS). This paper presents a novel traffic information acquisition system, i.e., a dynamic traffic information acquisition system based on wireless mesh networks (WMN). The system comprises of probe vehicles and wireless mesh networks. Compared to the conventional systems, it is independent of other network infrastructures and easy to implement. It can acquire the real-time traffic information correctly with lower cost.     

复杂行车环境下的前方车辆检测算法研究

针对复杂行车环境下的智能车辆行车安全问题,提出了一种基于特征的多目标前方车辆检测算法。算法首先利用车辆底部阴影特征、车辆轮廓特征的先验知识,探测前方感兴趣区域,然后利用车辆边界特征、对称性特征对感兴趣区域进行判别。该算法针对复杂路况下的车辆分布特征进行了适应性设计。能够快速、准确的检测到具有潜在安全威胁的前方行驶车辆。     

Toward a deep CNN and RS-GOA framework for vehicle detection,traffic flow estimation,and optimal path selection from surveillance videos

Several autonomous traffic monitoring systems have been created as a result of the growing number of vehicles in urban areas. Traffic surveillance systems that use roadside cameras, in particular, are becoming widely used for traffic management. For an efficient traffic control and vehicle navigation system, accurate traffic flow information must be obtained based on the vehicles detected in surveillance videos. However, vehicles of various scales are difficult to spot in traffic surveillance videos due to the presence of barricades, other vehicles, and the impact of poor lighting. Also, adverse weather conditions like snow, fog, and heavy rain diminish the visual quality of the surveillance footage. This paper proposes multi-scale dense nested deep CNN (MSDN-DCNN) and regional search grasshopper optimization algorithm (RS-GOA) framework to accurately detect the vehicles, estimate the traffic flow, and find the optimal path with less travel time. First, the surveillance videos are pre-processed, which includes frame conversion, redundancy removal, and image enhancement. The pre-processed frames are given as input to the MSDN-DCNN for multi-scale vehicle detection. The detected results are used for vehicle counting and estimating the traffic flow. Finally, the optimal path is chosen based on the traffic flow information by using the RS-GOA algorithm. The performance of the proposed method is compared with the existing vehicle detection and path selection techniques. The results illustrate that the proposed Deep CNN-RS-GOA framework has improved performance with high detection accuracy (91.03%), high speed (53.9 fps), less running time (1,000 ms), less travel time, and faster convergence.     

智能交通控制系统在城市交通指挥中的应用

针对近年来城市交通的拥挤现象，特别是驾驶员违章严重、交通事故频发、车辆尾气污染超标等问题，介绍丁集计算机、信息、电子及通讯等众多高新科技手段于一体的智能交通指挥中心控制系统。该系统的安装及使用，大大缓解了城市道路堵塞现象、提高了道路的通行能力，减少了驾驶员违章的次数，抑制了交通事故的发生，同时对减轻车辆尾气排放，从而降低环境污染都起到了不可低估的作用。     

基于分形点过程自相似流的队列性能分析

通过对交换机排队系统进行仿真,分析了以分形点过程( FPP )自相似业务流为输入的排队系统的性能.仿真结果显示,自相似业务流量模型下队列的性能与传统指数流量模型下的队列性能大不相同.文中所获得的仿真结果可用于网络流量模型、网络设计、网络拥塞控制和流量工程等.     

MPLS流量工程及基于约束路由计算的研究

论述了 MPLS 网络的架构及其对流量工程的支持,研究了基于 MPLS 流量工程要解决的几个主要问题：如何把数据包映射为转发等价类等,并对其中最重要的一个——通过 LSP 把流量中继映射到实际网络拓扑,提出了一种约束最短路径优先算法的实现方法。     

车载实时路况自动播报系统的研究

为了解决交通拥堵带来的出行不便问题,研究提出一种实时路况语音播报系统,其特点在于不通过现有导航显示仪而仅以语音方式来实时播报交通路况信息,由此可在不影响车辆驾驶情况下,将车辆行驶前方交通路况信息实时告知驾驶员,使驾驶员能够提前预知前方交通路况,并据此规避拥挤路段,免受堵车烦恼,并快捷省时地到达目的地。     

The distributed robust traffic controller for ATM networks

We propose an approach to design a distributed rate‐based traffic controller to flow‐regulate the best‐effort service (e.g. ABR) traffic and guaranteed service traffic through an ATM switch. The controller is distributed among the source nodes and has a very simple structure. Its local controller at each source node is open‐loop stable and only requires the knowledge of the buffer occupancy at the bottleneck switch. We show that this controller is fair and is not sensitive to the change of VCs over time. It does not have oscillation and can achieve a high utilization. Copyright © 2001 John Wiley & Sons, Ltd.     

带有业务感知分类的低开销保护策略

为将IP业务准确分类,并根据所分优先级类别进 行高效合理的区分保护,提出一种带有业务感知分 类的网络保护策略(PSTAC)。定义信息重要度(IS)感知业务特征 ,结合贝叶斯理论建立业务优先级分类模型,并考虑不 同级别业务的QoS参数进行针对性保护。仿真结果表明,所提PSTAC实现了高精度的业务分类 ,且比传统的区分保护策略有更高的资源利用率和更低的网络阻塞率。     

用Java编程模拟实现城市交通控制系统

本系统实现车流量数据采集、交通灯的设计与控制、车辆实时分流、交通应急管制四个功能。车流量数据采集可以给交通信号灯时间显示和车辆分流提供依据。交通信号灯的设计采用多线程技术,实现东西方向和南北方向交通灯交替显示。车辆分流作用是在某条路的车流量超出它的最大承载量时给司机提出最佳换行路线。     

基于IP/MPLS网络的动态业务流量矩阵测量模型

IP网络动态业务流量矩阵的测量是业务量工程研究中的一个难点,本文提出了一种面向IP/MPLS骨干网络的基于LSP级的动态业务流量矩阵测量模型。该模型能够获取网络边界处对应于每一条LSP的路径转发信息,并根据每一条LSP上的测量结果,计算得知全网的业务流量矩阵。文中证明该测量模型是可行的,并给出了相关的算法及其性能分析。模型的优点是测量只在网络边界处进行而不涉及网络核心,故引起的网络开销较小。另外模型所需的算法复杂度低,仿真结果显示测量模型是有效的。     

A bandwidth assignment algorithm on a satellite channel for VBR traffic

Variable bit rate (VBR) video is currently by far the most interesting and challenging real-time application. A VBR encoder attempts to keep the quality of video output constant and at the same time reduces bandwidth requirements, since only a minimum amount of information has to be transferred. On the other hand, as VBR video traffic is both highly variable and delay-sensitive, high-speed networks (e.g. ATM) are generally implemented by assigning peak rate bandwidths to VBR video applications. This approach may, however, be inefficient in a satellite network based on a TDMA scheme. To overcome this problem, we have designed a demand assignment satellite bandwidth allocation algorithm in TDMA, named V2L-DA (VBR 2-Level Demand Assignment), which manages the VBR video traffic according to a dynamic bandwidth allocation algorithm. In this paper we discuss how to tune the proposed algorithm in order to optimize network utilization when MPEG-1 VBR video traffic is being transmitted. Our results indicate that most of the time only 40% of the peak rate bandwidth is needed to satisfy the VBR source, so the remaining 60% of the peak rate bandwidth can be used to transmit the datagram traffic queued in the network stations. © 1997 John Wiley & Sons, Ltd.     

一种基于频繁序列匹配的交通状态趋势预测方法

海量的交通流数据中一定隐藏着某些潜在的交通状态演变规律,然而少有研究能以实验的方法支持这种观点。本文提出一种基于频繁序列匹配的交通状态趋势预测方法：首先,介绍交通状态序列模型及序列切分处理,其次,提出投影压缩序列相似度计算方法及序列匹配算法,第三,讨论基于频繁序列匹配的交通序列预测算法。通过真实采集数据验证本文提出的方法可行有效。