Spatial-temporal traffic flow pattern identification and anomaly detection with dictionary-based compression theory in a large-scale urban network

Traffic flow pattern identification, as well as anomaly detection, is an important component for traffic operations and control. To reveal the characteristics of regional traffic flow patterns in large road networks, this paper employs dictionary-based compression theory to identify the features of both spatial and temporal patterns by analyzing the multi-dimensional traffic-related data. An anomaly index is derived to quantify the network traffic in both spatial and temporal perspectives. Both pattern identifications are conducted in three different geographic levels: detector, intersection, and sub-region. From different geographic levels, this study finds several important features of traffic flow patterns, including the geographic distribution of traffic flow patterns, pattern shifts at different times-of-day, pattern fluctuations over different days, etc. Both spatial and temporal traffic flow patterns defined in this study can jointly characterize pattern changes and provide a good performance measure of traffic operations and management. The proposed method is further implemented in a case study for the impact of a newly constructed subway line. The before-and-after study identifies the major changes of surrounding road traffic near the subway stations. It is found that new metro stations attract more commute traffic in weekdays as well as entertaining traffic during weekends.     

轨道交通声屏障声学设计思路探讨

随着轨道交通建设的发展,交通噪声的污染越来越严重。声屏障作为一种降低交通噪声有效的方法,越来越受到人们的重视。声屏障设计是一个综合复杂的问题,需要考虑多项因素,包括声学特性、景观效果、结构安全、防火性能以及维护保养等,但最主要的还是声学设计。     

Use of magnetic monitoring of vehicles for proactive strategy development

The proactive operational strategy in the transport system which is a parallel concept associated with the Intelligent Transportation System (ITS) seems to be modern and right direction of development. However, the basis for its operation is the “information” in the broad sense of the term, on the functioning of the transport system itself. As new technologies develop, there emerge new opportunities of putting to use a wide array of sensors which can deliver more complete traffic data but using complex matrix of sensors is often unjustified economically and confusing. The paper proposes use of magnetometers as an interesting alternative to pass the requirements of simplicity of application, minimum costs and maximum of acquired information. The process of obtaining the information requires analysis of the quantitative and qualitative changes of the magnetic field. The conducted analyses demonstrate the possibility of using the passive magnetic methods for the purpose of monitoring of vehicles. Placement of the magnetic sensor bear out an important issue and was also discussed. During the experimental research it has been proven that passive magnetic methods enable obtaining the information on the movement of a vehicle as well as on the vehicle itself. Estimations of such values as: vehicle’s moving direction, velocity, dimensions, clearance or mass having ferromagnetic properties and even the state of strain in a vehicle’s structure were confirmed in practice. In addition thanks to magneto-mechanical effects the theoretical possibility of assessing the stress occurring in the components of vehicles, which could be indicative of the volume of cargo carried. Moreover, the crash experiment showed the possibility of a collision detection using magnetic signal. The need for obtaining information increases from year to year, with information becoming the biggest asset which enables both development and effective use of the transport system. Included researches, proofs emerging opportunity of more extensive use of magnetic sensors and the passive magnetic methods which could be applied in the modern transportation system.     

相干信号源的空间平滑法处理及其效果分析

介绍了相干信号DOA空间平滑技术处理的方法及其效果分析，并给出了处理非相干和相干信号源的仿真结果，实验结果证明了空间平滑技术能够去相干性，达到了对相干信号源的方向进行识别的目的。     

铁路GSM-R干扰模型及快速干扰识别与判定方法

针对铁路GSM-R通信系统所需的高可靠性和高传输质量的特性,通过对GSM-R受干扰情况的建模与分析,归纳并得出了3种常见GSM-R干扰的干扰模型,并基于此提出了一种基于通信信号与底部噪声两个层次的快速干扰识别方法及对应的判定方法。相对以往的识别与判定流程,该方法具有较低的计算复杂度,使得快速地发现干扰、识别干扰更加容易实现,且更有益于进一步的定位干扰与消除干扰。     

桥梁施工中的风险识别和风险评价

分析桥梁工程施工中常见风险的特点和风险事故,提出了风险识别依据和识别方法,并探讨了风险评价准则和风险评价法,以期为保障桥梁工程的施工质量提供参考.     

基于高频注入的永磁同步电机参数辨识策略

永磁同步电机高性能控制依赖电机参数和磁极初始位置的准确性,辨识磁极初始位置可以保证无位置传感器矢量控制启动过程的平稳性。传统的参数辨识方法辨识过程较为复杂或者精度不高,本文提出了一种易于实现的高频注入控制算法,通过注入高频电压,提取高频电流,就可以直接快速辨识出永磁同步电机电感,再通过注入两个脉冲电压矢量,就可以辨识磁极初始位置。这种方式辨识精度高,快速性好,工程实现方便,而且不需要转动电机,具有广泛的实用性。     

次级通道在线辨识的双层隔振系统振动主动控制

次级通道离线辨识限制了自适应控制的适用性,次级通道发生突变后,离线辨识的控制效果很差。本文在Eriksson在线辨识模型的基础上,通过变步长和调整滤波器阶数,对在线辨识模型进行优化,并将其运用到双层隔振系统。将白噪声引入控制输出端,在保证系统稳定的前提下调整滤波器阶数,以变步长LMS算法调整FIR滤波器权值系数,为次级通道进行实时在线参数辨识。仿真结果表明,优化后的次级通道在线辨识算法能有效抑制单频振动和多频振动,次级通道发生突变时,在线辨识控制效果优于离线辨识。     

闸楼房无人值守系统的设计与实现

主要介绍闸楼房无人值守系统的设计、实现及运用效果.该系统主要利用射频识别和计算机技术,通过在机车上安装射频IC卡,在车务部门与机务段分界点的闸楼房安装扫描读卡装置,实现机车出入信息的自动识别、采集与处理,并利用现有网络通道,实现铁路局、车务部门和机务段3级网络的信息共享,使各级运输管理人员都能够实时掌握机车出入及运用情况.     

水源热泵及其应用前景

主要介绍水源热泵这一利用浅层低温地热“绿色技术”的概念和主要特点,预言该技术的应用前景将十分广阔.