队列车辆碰撞严重性及车队排布策略

针对自动驾驶车辆队列发生不可避免碰撞的事故场景,研究以整体碰撞严重性达到最低为目标的车队排布策略.首先根据引发事故的障碍物是否会明显影响领航车运动,将碰撞划分为队内碰撞和队外碰撞.队列几何构型一定时,针对均质化队列发生一维碰撞过程建立理论模型,计入碰撞前车辆对前车紧急制动的感应及自车进行紧急制动的过程,计算并定义时间截...     

基于扩展摩尔邻域的自由飞行冲突风险研究

为解决三维空间中,自由飞行条件下航空器间的飞行冲突风险判定问题,提出了基于扩展摩尔邻域的飞行冲突风险判定方法.首先分析平面摩尔近邻模型的特点,将其扩展至三维离散空间;然后建立水平、垂直飞行冲突风险可能性表格,提出计算三维飞行冲突风险的方法;最后分别用水平、垂直飞行冲突风险分开和同时计算的方法对同一仿真数据进行计算.结果表明:采用扩展的三维不同层摩尔邻域可以实现空域内航空器的飞行冲突风险的快速计算;水平、垂直飞行冲突风险同时计算的方式可以更快速地解决问题;同时,空间基础单元的间隔选择也会极大影响模型的运算效率.     

Traffic conflict models to evaluate the safety of signalized intersections at the cycle level

The safety of signalized intersections has often been evaluated at an aggregate level relating collisions to annual traffic volume and the geometric characteristics of the intersection. However, for many safety issues, it is essential to understand how changes in traffic parameters and signal control affect safety at the signal cycle level. This paper develops conflict-based safety performance functions (SPFs) for signalized intersections at the signal cycle level. Traffic video-data was recorded for six signalized intersections located in two cities in Canada. A video analysis procedure is proposed to collect rear-end conflicts and various traffic variables at each signal cycle from the recorded videos. The traffic variables include: traffic volume, maximum queue length, shock wave characteristics (e.g. shock wave speed and shock wave area), and the platoon ratio. The SPFs are developed using the generalized linear models (GLM) approach. The results show that all models have good fit and almost all the explanatory variables are statistically significant leading to better prediction of conflict occurrence beyond what can be expected from the traffic volume only. Furthermore, space-time conflict heat maps are developed to investigate the distribution of the traffic conflicts. The heat maps illustrate graphically the association between rear-end conflicts and various traffic parameters. The developed models can give insight about how changes in the signal cycle design affect the safety of signalized intersections. The overall goal is to use the developed models for the real-time optimization of signalized intersection safety by changing the signal design.     

Life cycle strategies of free-living copepods in fresh waters

Freshwater copepods live in habitats characterized by a high degree of instability. To survive occasional deterioration of their environment copepods have evolved adaptive mechanisms like dormancy or migration in order to avoid lethal conditions and to synchronize growth and reproduction with favourable abiotic and biotic conditions. Typical life cycles of harpacticoid, calanoid and cyclopoid copepods are presented to show strategies that have evolved to survive threatening environmental conditions.     

基于数据融合的单目标船避碰评估系统

建立了一个用于对单目标船避碰操作进行评估的系统。介绍了基于数据融合技术的系统三级处理模型,并重点讨论了基于数据关联的船舶航迹提取,基于坐标转换和几何模型的船舶运动参数计算,基于多测量周期数据融合的船舶操纵识别,和基于知识的碰撞危险、避碰阶段及会遇态势的判定等模块。同时给出了系统的工作流程图,最后通过实例说明系统运行的有效性。     

会聚追越/交叉中两船的避让

从讨论构成追越的条件和追越船的责任出发,分析了会聚追越/交叉态势下两船容易发生碰撞的原因和两船的避让关系,并提出了此种会遇态势下的避让注意事项。     

城市道路路段和交叉口阻抗函数探讨

城市道路的路阻函数是交通研究中的关键点和难点．对交通分配起着至关重要的作用。本文先对城市道路路段阻抗函数进行细致的分析，通过实际调查的数据对该函数进行了验证。对信号交叉口的路阻函数进行了比较详细的分析，提出了隐性冲突点的概念，对信号交叉口阻抗函数中添加了与流向有关的心理参数项，并进行了分析和标定。     

浅谈监理的安全责任与监理企业的安全文化建设

从理论和实践的角度,简要论述了监理的安全责任、安全监理的措施和手段、安全文化的建设以及如何应对安全监理的风险。     

路段交通冲突技术研究

对路段交通冲突进行定义和分类，着重研究严重冲突的判别标准和分级标准是对现有交通冲突技术理论的一种完善和改进，为路段交通安全分析评价提供一种新的研究途径。     

Conflict‐free time‐based trajectory planning for aircraft taxi automation with refined taxiway modeling

To mitigate airport congestion caused by increasing air traffic demand, the trajectory‐based surface operations concept has been proposed to improve surface movement efficiency while maintaining safety. It utilizes decision support tools to provide optimized time‐based trajectories for each aircraft and uses automation systems to guide surface movements and monitor their conformance with assigned trajectories. Whether the time‐based trajectories can be effectively followed so that the expected benefits can be guaranteed depends firstly on whether these trajectories are realistic. So, this paper first deals with the modeling biases of the network model typically used for taxi trajectory planning via refined taxiway modeling. Then it presents a zone control‐based dynamic routing and timing algorithm upon the refined taxiway model to find the shortest time taxi route and timings for an aircraft. Finally, the presented algorithm is integrated with a sequential planning framework to continuously decide taxi routes and timings. Experimental results demonstrate that the solution time for an aircraft can be steadily around a few milliseconds with timely cleaning of expired time windows, showing potential for real‐time decision support applications. The results also show the advantages of the proposed methodology over existing approaches. Copyright © 2015 John Wiley & Sons, Ltd.