Fault-tolerant control of variable speed limits for freeway work zone using likelihood estimation

Freeway work zone with lane closure can lead to disruption to local traffic and cause significant impacts on mobility, safety and environmental sustainability. To mitigate traffic congestion near work zone area, many variable speed limits (VSL) control approaches have been developed. However, VSL control system, as a critical transportation management system, is prone to the occurrence of traffic sensor faults. Faulty sensors can cause great deviations of traffic measurements and system degradation. Therefore, this study aims to develop a fault-tolerant VSL control strategy for freeway work zone with the consideration of the mainline sensor fault and ramp sensor fault. To analyze the traffic dynamics near work zone area, a traffic flow model has been built first. Then a sliding mode controller in the previous study has been utilized for VSL control. In addition to the traffic states estimated by a Kalman filter, two observers have been developed to provide analytical redundancy of traffic states estimation. By comparing the logarithm of the likelihood estimations from the Kalman filter and two observers, a fault diagnosis scheme has been designed to detect and identify the faults of mainline sensors and ramp sensors. Then the VSL controller can be reconfigured accordingly in case of sensor faults. The proposed system is implemented and evaluated under a realistic freeway work zone environment using traffic simulator SUMO. The results demonstrate that the developed system can accurately detect and identify the sensor faults in real time. Consistent improvements of mobility, safety and sustainability are also achieved under fault-free and sensor faults scenarios.     

基于SOC+FPGA的航管雷达终端综合记录系统设计

针对航管雷达终端对显示画面、雷达视频、监控视频、台位语音、航迹数据、操控数据等信息的综合记录需求,对各类数据的特征和应用场景进行了研究,采用了以集成ARM A9处理器和视频编解码引擎的SOC为主,高性能FPGA为辅的综合记录系统架构,高速、高集成度电路设计方法和模块化、并行化的软件设计方法,高效、灵活的音视频压缩算法,实现了一种基于SOC+FPGA的航管雷达终端综合记录系统。解决了现有记录系统数据记录信息不完整、记录时长短、设备量大等问题。经实际产品测试,该综合记录系统满足了航管雷达终端记录的各项功能、性能指标,具备产品推广应用的条件。     

基于物联网的高速公路主动发光诱导系统设计

近年来,交通压力与日俱增,高速公路的安全问题也日益凸显。研究表明,低能见度环境会导致交通安全事故发生机率提升。因此,提高高速公路低能见度环境下交通诱导水平从而提升交通运行的安全性愈加重要。为了解决上述问题,提出了一种基于物联网的高速公路路侧主动发光诱导系统。该系统基于智能检测技术和局域网构建技术,通过协同短距离Zigbee通信技术和长距离光纤通信技术,构建高速公路智能化监测控制网络,通过车-路协同控制路侧发光诱导装置对低能见度环境下的高速运行车辆进行有效诱导,提高高速公路的交通安全性。通过模拟实验,该系统能够大大降低设备铺设路段交通安全事故的发生率,且相比于原有LED发光设备,该系统也具有更好的节能效果。     

基于层次分析法的管制中心系统效能评估

针对管制中心系统,利用层次分析法评估其系统效能。分析影响管制中心效能的各类因素,建立适合我国军民航特点的管制中心系统效能指标体系和度量标准;利用专家提供的各个指标之间的相对重要性,构造判断矩阵确定其权重;最后利用概率乘法递归地求出各指标相对于系统效能的权重系数,管制中心系统效能值等于各指标权重与其所对应的隶属度乘积的线性加权值。仿真得出的评估值和专家的结论基本一致,表明了利用层次分析法评估管制中心系统效能的合理性。     

基于OTDR的光路监测终端设计

针对目前光纤通信网络规模的不断扩大以及人们对光通信网可靠性的需求,该文研制了一种基于OTDR的光路监测终端。该装置由数据处理模块、光路监测模块、电源模块、人机交互模块等组成。数据处理模块由STM32F407芯片及其子系统组成;光路监测模块由OPM模块以及OTDR模块组成,OPM模块对光路性能参数进行监控,包括功率、波长等,用于发现光路故障,OTDR模块可检测到故障点与监测终端的距离;电源模块由开关电源模块与降压芯片组成,能将220 V交流电转换为5 V/3.3 V直流电,为CPU以及各模块提供电源;人机交互模块采用了0.96寸OLED和GPRS模块组成。软件基于轮询的方式,将监测模块采集的数据进行故障分析,定位故障点,将位置信息以短信方式发送给维护人员,并在OLED上显示光路故障告警信息。     

1050 MW火电厂现场总线故障诊断研究

基于现场总线系统网络拓扑结构,从硬件、软件两方面系统地介绍现场总线主站、光电转换器、光缆、终端电阻等环节,结合1050 MW火电厂现场总线在基建调试和正常运行期间出现的各类故障,深入剖析故障根源,提出故障诊断方法和解决方案。以脱硫系统网段故障为案例,利用ProfiTrace诊断,解决了DP设备通信板故障、DP电缆断路等问题。     

光纤传感器与激光测距的物位传感器设计

以固体火箭发动机推进剂装药物位检测系统研究为背景,采用基于光纤传感器与激光测距原理的非接触式物位检测方案,使用光纤传导激光,使带电设备远离检测现场,可以在检测现场完全不带电的情况下实现高精度物位检测。系统通过主控单元可以控制多个传感器实现多点同时检测,从而能够在装药表面不是绝对平面的情况下得到更为可靠的检测结果。     

基于光纤传感技术的局部放电超声信号检测方法研究

电力设备局部放电易引发电气短路故障,传统的电检测方法针对单点测量,在长距离测量上受到局限.分析了局部放电的参数特征,设计了一种检测局部放电信号的光纤环结构,并构建了基于Sagnac干涉原理的光纤传感局部放电检测方案.在实验室环境下模拟电力设备局部放电,搭建了局部放电光纤检测系统,传感光纤总长度为8.398 km,进行局部放电检测试验.试验证明,在10 kV电压等级下,局部放电时域信号幅值范围为0.1 V~1.8 V,频率响应范围为可达60 kHz,研究表明该方法具有灵敏度高、频率响应范围宽等特点,为电力设备局部放电检测提供了新的思路.     

三维空管自动化系统投影技术研究

新一代空中交通管理系统的核心任务是对飞行器的四维航迹进行管理,而实现四维航迹有效显示的重要途径之一为三维透视投影技术。针对空管自动化系统的实际需求,求得三维空间透视投影的旋转矩阵及投影矩阵,给出一种新的投影算法,并结合三维地图软件对实际飞行器的标牌显示进行实验。实验结果表明所提出的方法可以实现三维空间到二维投影面的变换,是一种有效且可行的三维空间透视投影算法。     

An integrated design of a satellite-based navigation system for air traffic control

This paper focuses on the microprocessor-based computer architecture necessary to integrate the Department of Defense's Global Positioning System into the Federal Aviation Administration's (FAA) main frame computers. It incorporates what is defined as an Automated Dependent Surveillance (ADS) concept for air traffic control. The ADS system is dependent upon receiving position information from the aircraft's equipment as opposed to the independent ‘skin paint’ received from a radar.After a brief introduction and background, the authors' detailed design is presented depicting the distinctive manner in which the hardware and software were committed and modified in the main frame computer and the design approach for the avionics equipment to permit the Global Positioning System to be employed for air traffic control.