Recent advances in intelligent transportation system allow traffic safety studies to extend from historic data-based analyses to real-time applications. The study presents a new method to predict crash likelihood with...Recent advances in intelligent transportation system allow traffic safety studies to extend from historic data-based analyses to real-time applications. The study presents a new method to predict crash likelihood with traffic data collected by discrete loop detectors as well as the web-crawl weather data. Matched case-control method and support vector machines （SVMs） technique were employed to identify the risk status. The adaptive synthetic over-sampling technique was applied to solve the imbalanced dataset issues. Random forest technique was applied to select the contributing factors and avoid the over-fitting issues. The results indicate that the SVMs classifier could successfully classify 76.32% of the crashes on the test dataset and 87.52% of the crashes on the overall dataset, which were relatively satisfactory compared with the results of the previous studies. Compared with the SVMs classifier without the data, the SVMs classifier with the web-crawl weather data increased the crash prediction accuracy by 1.32% and decreased the false alarm rate by 1.72%, showing the potential value of the massive web weather data. Mean impact value method was employed to evaluate the variable effects, and the results are identical with the results of most of previous studies. The emerging technique based on the discrete traffic data and web weather data proves to be more applicable on real- time safety management on freeways.展开更多
基于嵌入式实时操作系统FreeRTOS和可变速率控制器局域网(Controller Area Network with Flexible Data Rate,CAN FD),设计并实现了基于统一诊断服务(Unified Diagnostic Services,UDS)协议的车辆诊断系统,包括微控制器程序、上位机测...基于嵌入式实时操作系统FreeRTOS和可变速率控制器局域网(Controller Area Network with Flexible Data Rate,CAN FD),设计并实现了基于统一诊断服务(Unified Diagnostic Services,UDS)协议的车辆诊断系统,包括微控制器程序、上位机测试程序和连接二者的支持CAN FD功能的USB/CAN转换器。微控制器程序设计使用嵌入式操作系统FreeRTOS建立软件框架,开发了传输层任务、应用层任务和CAN中断服务程序。上位机测试程序针对数据读写和在线编程功能进行重点测试。结果表明,该文使用的设计方案能满足ISO 14229-1-2020规范中要求的响应时间要求,同时具有可靠、易于维护等优势。展开更多
文章针对通信电源系统易受多种因素影响的特点,开发了一种基于高级精简指令集计算机机器(Advanced Reduced Instruction Set Computer Machines,ARM)核心控制芯片和通用分组无线业务(General Packet Radio Service,GPRS)数据传输单元(Da...文章针对通信电源系统易受多种因素影响的特点,开发了一种基于高级精简指令集计算机机器(Advanced Reduced Instruction Set Computer Machines,ARM)核心控制芯片和通用分组无线业务(General Packet Radio Service,GPRS)数据传输单元(Data Transfer Unit,DTU)模块的实时监测系统。系统通过现场控制终端采集通信电源设备的运行状态信息,经模拟数字(Analog to Digital,AD)转换模块处理后,由ARM核心控制芯片发送至无线模块,最终传输至远程监控中心。此外,设计一套应急预案,包括应急预案设计原则、组织机构与职责、应急分级、启动条件与工作流程以及保障措施等,以应对电网大停电带来的经济损失。通过技术保障、装备保障、人员保障,实现抢修工作的快速响应,缩短断电时间,有效减少经济损失,确保生产生活不受影响。展开更多
基金supported by the National Natural Science Foundation (71301119)the Shanghai Natural Science Foundation (12ZR1434100)
文摘Recent advances in intelligent transportation system allow traffic safety studies to extend from historic data-based analyses to real-time applications. The study presents a new method to predict crash likelihood with traffic data collected by discrete loop detectors as well as the web-crawl weather data. Matched case-control method and support vector machines （SVMs） technique were employed to identify the risk status. The adaptive synthetic over-sampling technique was applied to solve the imbalanced dataset issues. Random forest technique was applied to select the contributing factors and avoid the over-fitting issues. The results indicate that the SVMs classifier could successfully classify 76.32% of the crashes on the test dataset and 87.52% of the crashes on the overall dataset, which were relatively satisfactory compared with the results of the previous studies. Compared with the SVMs classifier without the data, the SVMs classifier with the web-crawl weather data increased the crash prediction accuracy by 1.32% and decreased the false alarm rate by 1.72%, showing the potential value of the massive web weather data. Mean impact value method was employed to evaluate the variable effects, and the results are identical with the results of most of previous studies. The emerging technique based on the discrete traffic data and web weather data proves to be more applicable on real- time safety management on freeways.
文摘基于嵌入式实时操作系统FreeRTOS和可变速率控制器局域网(Controller Area Network with Flexible Data Rate,CAN FD),设计并实现了基于统一诊断服务(Unified Diagnostic Services,UDS)协议的车辆诊断系统,包括微控制器程序、上位机测试程序和连接二者的支持CAN FD功能的USB/CAN转换器。微控制器程序设计使用嵌入式操作系统FreeRTOS建立软件框架,开发了传输层任务、应用层任务和CAN中断服务程序。上位机测试程序针对数据读写和在线编程功能进行重点测试。结果表明,该文使用的设计方案能满足ISO 14229-1-2020规范中要求的响应时间要求,同时具有可靠、易于维护等优势。
文摘文章针对通信电源系统易受多种因素影响的特点,开发了一种基于高级精简指令集计算机机器(Advanced Reduced Instruction Set Computer Machines,ARM)核心控制芯片和通用分组无线业务(General Packet Radio Service,GPRS)数据传输单元(Data Transfer Unit,DTU)模块的实时监测系统。系统通过现场控制终端采集通信电源设备的运行状态信息,经模拟数字(Analog to Digital,AD)转换模块处理后,由ARM核心控制芯片发送至无线模块,最终传输至远程监控中心。此外,设计一套应急预案,包括应急预案设计原则、组织机构与职责、应急分级、启动条件与工作流程以及保障措施等,以应对电网大停电带来的经济损失。通过技术保障、装备保障、人员保障,实现抢修工作的快速响应,缩短断电时间,有效减少经济损失,确保生产生活不受影响。
