基于WebGIS的车辆监控系统的性能优化研究

发布时间：2018-01-04 05:33

本文关键词：基于WebGIS的车辆监控系统的性能优化研究　出处：《南京邮电大学》2015年硕士论文　论文类型：学位论文

【摘要】：近些年我国车辆数量的迅速增长给交通带来了严重的问题,智能交通成了解决这些问题的关键。基于万维网地理信息系统(World Wide Web Geographic Information System, WebGIS)的车辆监控系统通过融合先进的通信技术、电子技术、地理信息技术,对传统的交通运输系统进行了改造,使得交通信息的获取、传输更加智能、快速、准确。然而在实际应用中,海量的轨迹数据、多客户端的高并发访问引发了许多系统性能问题。为了解决这些问题,本文从两个方面提出了系统性能优化策略。首先,针对轨迹查询、存储过程中由于轨迹数据量庞大所带来的查询效率低、存储空间不足、用户响应时间慢等问题,提出了基于综合时空特性的混合式轨迹压缩算法。该算法一方面采用了新的综合时空特性的在线轨迹压缩策略,利用GPS数据的位置信息、时间信息、方向角、速度信息进行轨迹特征点的综合判断,以更准确地选取特征点；另一方面,采用了在线与批处理相结合的混合式轨迹压缩策略,定时采用道格拉斯批量压缩算法对在线压缩的轨迹集进行二次压缩,以提高轨迹的压缩效率。实验结果表明,较现有的时空特性压缩算法,新的综合时空特性在线轨迹压缩策略虽然在压缩率上略有下降,但压缩误差有显著减少。进一步采用混合式压缩策略后,通过选取适当的批处理时间周期,所提算法在压缩率和压缩误差上较现有的时空特性算法均有所改进。接着,针对多台车载终端并发访问通信平台时集群服务器之间负载分配不平衡的问题,提出了一种基于动态反馈的负载性能比调度算法。该算法在加权最小连接调度算法和动态反馈调度算法的基础上,引入负载性能比、负载容余量用于负载分配的判断条件。测试结果表明,较加权最小连接调度算法和动态反馈调度算法,所提的算法在平均响应时间和吞吐率上均有所改进,负载能更均衡的分布于集群的节点上。最后,本文实现了基于WebGIS的车辆监控原型系统。该系统由车载终端、通信平台、应用平台组成,融合了全球定位系统(Global Positioning System, GPS)、WEB、地理信息系统(Geographic Information System, GIS)技术,并实现了本文所提出的轨迹压缩和负载均衡算法。实验结果表明通过性能优化不仅大幅度的提高了整个系统的处理速度,减小了用户请求响应时间,而且提高了整个系统的稳定性,有效的解决系统的性能问题。
[Abstract]:In recent years, the rapid growth of the number of vehicles in China has brought serious problems to the traffic. Intelligent transportation has become the key to solve these problems. Based on the World wide Web Geographic Information system (. World Wide Web Geographic Information System. WebGIS-based vehicle monitoring system integrates advanced communication technology, electronic technology, geographical information technology, the transformation of the traditional transportation system, so as to obtain traffic information. Transmission is more intelligent, faster and more accurate. However, in practical applications, massive track data, multi-client high concurrent access has caused a lot of system performance problems, in order to solve these problems. In this paper, the system performance optimization strategy is proposed from two aspects. Firstly, for trajectory query, the query efficiency caused by the large amount of track data is low, and the storage space is insufficient. Based on the slow response time, a hybrid trajectory compression algorithm based on integrated space-time characteristics is proposed. On the one hand, a new on-line trajectory compression strategy is proposed. The location information, time information, direction angle and velocity information of GPS data are used to judge the locus feature points in order to select the feature points more accurately. On the other hand, the hybrid trajectory compression strategy combined with online and batch processing is adopted, and Douglass batch compression algorithm is used to compress the trajectory set twice. The experimental results show that compared with the existing space-time characteristic compression algorithm, the new on-line trajectory compression strategy with integrated space-time characteristics has a slight decrease in compression ratio. However, the compression error is significantly reduced. After adopting the hybrid compression strategy, the appropriate batch processing time period is selected. The proposed algorithm improves the compression ratio and compression error compared with the existing space-time characteristic algorithm. Secondly, the load distribution between cluster servers is unbalanced when multiple vehicle terminals access the communication platform concurrently. A load performance ratio scheduling algorithm based on dynamic feedback is proposed, which introduces load performance ratio on the basis of weighted minimum connection scheduling algorithm and dynamic feedback scheduling algorithm. The test results show that the proposed algorithm improves the average response time and throughput compared with the weighted minimum connection scheduling algorithm and the dynamic feedback scheduling algorithm. The load can be distributed more evenly on the nodes of the cluster. Finally, this paper implements the prototype system of vehicle monitoring based on WebGIS. The system is composed of vehicle terminal, communication platform and application platform. Integrated Global Positioning system (GPS) Global Positioning system, GPS / Web. Geographic Information system (GIS) technology. The proposed trajectory compression and load balancing algorithms are implemented. The experimental results show that the performance optimization not only improves the processing speed of the whole system, but also reduces the response time of the user request. Moreover, the stability of the whole system is improved and the performance problem of the system is effectively solved.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U495

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