Car following decisions under three visibility conditions and two speeds tested with a driving simulator

The National Highway Traffic Safety Administration web site reports that rear-end collisions in the United States exceed 1.5 million per year, or approximately 23% of all vehicle crashes. Car following behavior and the decision-making habits of drivers seem fundamental to understanding how to avoid these rear-end crashes. The present research aimed to reveal factors that govern car following under conditions of reduced visibility. It employed a KQ-Vection high-fidelity driving simulator to measure the behavior of automobile drivers following a lead vehicle at 13.4 m/s (30 MPH) or 22.4 m/s (50 MPH) under three visibility conditions--clear or one of two densities of simulated fog. At the higher speed, fog conditions separated participants into a group that stayed within visible range of the lead car, even though the headway time violated the NHTSA recommendations for the speed involved, and another group that lagged beyond the visible range. Data were compared to the model of Van Winsum for car following (The human element in car following models. Transportation Research Part F 2, 1999). Contrast and image size measurements allowed comparison to a standard contrast sensitivity function and allowed estimation of the JND term in the Van Winsum model.     

盐雾条件下染污绝缘子交流污闪特性

染污绝缘子表面污秽在盐雾中吸湿受潮,雾中的盐分沉积在绝缘子表面增大了其表面电导率,使得绝缘子闪络特性降低,绝缘子可能在较低电压甚至工作电压下发生闪络,威胁电网的安全稳定运行。本文对瓷、玻璃、复合三种典型绝缘子在不同盐密(SDD)和雾水电导率(?20)下的交流闪络特性进行试验研究,提出附加盐密(ASDD)的概念,分析了附加盐密与绝缘子表面盐密和雾水电导率的关系及其对交流闪络特性的影响。结果表明:随着盐密和雾水电导率的增大绝缘子交流雾闪电压均降低,且与盐密呈负幂指数关系,与雾水电导率呈线性关系。可以用附加盐密表征雾水电导率和盐密对绝缘子雾闪电压的综合影响,即附加盐密与雾水电导率和绝缘子盐密之积成正比。同时绝缘子闪络电压与绝缘子表面盐密和附加盐密之和呈负幂指数关系,绝缘子雾闪的本质是一种特殊的污秽闪络。     

高速公路雾区道路警示系统

该项目简要介绍了针对大雾等天气情况而采取的主动应对措施,提高了道路的通行能力,保障了道路交通安全.     

Driving in fog: The effects of driving experience and visibility on speed compensation and hazard avoidance

Inexperience is one of the strongest predictors for collisions, but it remains unclear how novice drivers differ from experienced drivers in terms of safety-related behavioural adaptations such as speed reduction in the presence of reduced visibility. To investigate the influence of driving experience on behavioural compensations to fog, average speed, speed variability, steering variability, collision rate, and hazard response time were measured in a driving simulator. Experienced drivers drove faster in clear visibility than novice drivers, yet they reduced their speed more in reduced visibility so that both groups drove at the same speed in simulated fog. Compared to experienced drivers, novice drivers had higher hazard response times, greater speed and steering variability, and were the only drivers to have collisions.     

雾计算平台的任务调度算法研究

雾计算平台中的任务调度问题是无法在多项式时间复杂度内求取精确解的NP-问题。本文在根据雾计算任务调度流程,构建雾计算平台任务调度数学模型基础上,采用改进人工蜂群算法,将任务调度映射为蜂群寻找蜜源的过程,在种群初始化阶段过引入混沌思想,改善了人工蜂群算法缺陷,扩大了蜂群搜索范围,避免陷入局部最优解。实验结果表明,改进后的人工蜂群算法具有更快的算法收敛速度,算法解析所对应的任务调度策略,也具有更高的任务处理总性能,表明本文所研究的改进人工蜂群算法,达到了提高雾计算资源利用率,提高雾计算任务处理效率的目的。     

雾天条件下的多尺度Retinex图像增强算法

在雾天条件下拍摄图像时,由于受到大气散射作用的影响,图像的颜色和对比度会出现退化现象。为了提高雾天图像的质量,提出一种改进的多尺度Retine雾天图像增强算法。首先采用幂次变换压缩图像动态范围;然后采用非线性变换对图像的高光区域进行抑制;最后采用反锐化掩模滤波消除图像模糊,增强雾天图像细节信息,并采用多幅雾天图像对算法性能进行仿真测试。仿真结果表明,改进多尺度Rctinc的雾天图像增强算法较好地解决了传统Retine算法存在的不足,加快了雾天图像增强的运行速度,使得雾天图像更加清晰化,获得了更优的视觉效果。     

雾衰减对雷达探测距离影响分析

对海面和低空目标探测时,雷达电波传播过程中会受到雾体衰减和散射噪声的影响.分析平流雾和辐射雾对电磁波的衰减及雾体散射带来天线辐射噪声温度增加等特性,构建雾衰减影响下的雷达探测距离模型.仿真分析典型频率火控雷达在不同俯仰角、能见度和媒介属性条件下的雷达探测性能,结果表明较高频率雷达受雾的影响较大,雾区内含水量越多对雷达影...     

基于分形特征的云雾遥感图像分离方法

雾是一种气象灾害,将雾从卫星云图上分离出来仍非易事。分数维给予图像纹理统计意义的描述,有效地体现了纹理的复杂度和粗糙度,揭示了纹理内在的自相似性,为云雾图像纹理分析提供了新的思路。简要阐述了纹理图像的差值盒维数计算方法,计算并分析了云雾纹理图像的差值盒维数特征。针对差值盒维数在表现云雾纹理特征和云雾分离方面存在的问题,提出基于样本图像灰度均值的加权盒维数算法,以改变出现灰值差异较大的不同云类具有相同盒维数的情况,并与云雾的光谱特征结合,实现雾与云的识别与分离,在实际应用     

Aging and the detection of imminent collisions under simulated fog conditions

The present study examined age-related differences in collision detection performance when contrast of the driving scene was reduced by simulated fog. Older and younger drivers were presented with a collision detection scenario in a simulator in which an object moved at a constant speed on a linear trajectory towards the driver. Drivers were shown part of the motion path of an approaching object that would eventually either collide with or pass by the driver and were required to determine whether or not the object would collide with the driver. Driver motion was either stationary or moving along a linear path down the roadway. A no fog condition and three different levels of fog were examined. Detection performance decreased when dense fog was simulated for older but not for younger observers. An age-related decrement was also found with shorter display durations (longer time to contact). When the vehicle was moving decrements in performance were observed for both younger and older drivers. These results suggest that under inclement weather conditions with reduced visibility, such as fog, older drivers may have an increased crash risk due to a decreased ability to detect impending collision events.     

Edge robotics: are we ready? an experimental evaluation of current vision and future directions

Cloud-based robotics systems leverage a wide range of Information Technologies (IT) to offer tangible benefits like cost reduction, powerful computational capabilities, data offloading, etc. However, the centralized nature of cloud computing is not well-suited for a multitude of Operational Technologies (OT) nowadays used in robotics systems that require strict real-time guarantees and security. Edge computing and fog computing are complementary approaches that aim at mitigating some of these challenges by providing computing capabilities closer to the users. The goal of this work is hence threefold: i) to analyze the current edge computing and fog computing landscape in the context of robotics systems, ii) to experimentally evaluate an end-to-end robotics system based on solutions proposed in the literature, and iii) to experimentally identify current benefits and open challenges of edge computing and fog computing. Results show that, in the case of an exemplary delivery application comprising two mobile robots, the robot coordination and range can be improved by consuming real-time radio information available at the edge. However, our evaluation highlights that the existing software, wireless and virtualization technologies still require substantial evolution to fully support edge-based robotics systems.