The estimation of a time-dependent OD trip table with vehicle trajectory samples

Abstract

In this paper we discuss a dynamic origin–destination (OD) estimation problem that has been used for identifying time-dependent travel demand on a road network. Even though a dynamic OD table is an indispensable data input for executing a dynamic traffic assignment, it is difficult to construct using the conventional OD construction method such as the four-step model. For this reason, a direct estimation method based on field traffic data such as link traffic counts has been used. However, the method does not account for a logical relationship between a travel demand pattern and socioeconomic attributes. In addition, the OD estimation method cannot guarantee the reliability of estimated results since the OD estimation problem has a property named the ‘underdetermined problem.’ In order to overcome such a problem, the method developed in this paper makes use of vehicle trajectory samples with link traffic counts. The new method is applied to numerical examples and shows promising capability for identifying a temporal and spatial travel demand pattern.     

城市大型居住区交通系统设计与优化

随着城市化进程的不断发展,大城市对于人口的吸引力日渐增强,作为解决大城市中心区住房难问题的一种方式,大型居住区在各大城市的数量也逐年增加.其巨大的出行需求使大型居住区成为城市动静态交通最为繁忙的地区,由此引发的一系列交通问题尤为严重.作者以大型居住区为研究对象,主要对居住区与周边道路衔接以及居住区周边配套公共交通设施完善等问题进行研究.通过实际调查对具体交通情况以及居民满意度进行分析,并通过对现有交通系统进行优化改进,以期改善当地的交通拥堵现状.     

吊车用电动机烧毁的故障分析及解决方案

应用电力拖动系统中的电动机这一理论,对某吊车用起升电动机屡次烧毁的实际案例进行分析,列出若干可能产生故障的原因,最终找出了导致电动机烧毁的根本原因。基于此理论,提出了若干全面、详尽的解决方案,进行可行性研究后最终选出最佳的技术改造方案。     

基于数据融合的路段行程时间估计

基于检测器数据的路段行程时间估计通常具有精度不高和可靠性差的特点。论文引入了自适应式卡尔曼滤波,采用K近邻法寻找相似的交通流状态来标定状态转移系数,建立了基于固定型检测器数据和移动型检测器数据的路段行程时间估计融合模型。实际数据的验证结果是,平均相对误差为9.52%,相对误差的标准差为8.92%。研究表明,与基于移动检测器数据的估计方法相比较,该方法极大地改善了估计精度和可靠性,还具有收敛速度快、对初值不敏感、参数少等特点。     

船舶总体弯曲对沿船体纵向布置齿轮机构的影响

船体中垂及中拱弯曲变形会使沿船体纵向布置的齿轮座的中心距产生增减。研究表明,正是由于这种中心距增减而引起的齿轮倾轧,不仅会导致齿轮发热、产生噪音及振动而且还会降低齿轮、齿轮轴以及轴承的疲劳寿命和增加能耗等。文章推导了一项适用于沿船体纵向布置的齿轮座的中心距补偿公式。为了形象说明问题,文中进行有限元分析。     

A data fusion approach for real-time traffic state estimation in urban signalized links

Real-time estimation of the traffic state in urban signalized links is valuable information for modern traffic control and management. In recent years, with the development of in-vehicle and communication technologies, connected vehicle data has been increasingly used in literature and practice. In this work, a novel data fusion approach is proposed for the high-resolution (second-by-second) estimation of queue length, vehicle accumulation, and outflow in urban signalized links. Required data includes input flow from a fixed detector at the upstream end of the link as well as location and speed of the connected vehicles. A probability-based approach is derived to compensate the error associated with low penetration rates while estimating the queue tail location, which renders the proposed methodology more robust to varying penetration rates of connected vehicles. A well-defined nonlinear function based on traffic flow theory is developed to attain the number of vehicles inside the queue based on queue tail location and average speed of connected vehicles. The overall scheme is thoroughly tested and demonstrated in a realistic microscopic simulation environment for three types of links with different penetration rates of connected vehicles. In order to test the efficiency of the proposed methodology in case that data are available at higher sampling times, the estimation procedure is also demonstrated for different time resolutions. The results demonstrate the efficiency and accuracy of the approach for high-resolution estimation, even in the presence of measurement noise.     

战术数据链技术现状及发展研究

介绍了数据链的概念与特点，美军及北约战术数据链的应用现状，并对战术数据链的发展趋势进行了分析。     

新能源汽车大数据应用的投资机会前瞻研究

新能源汽车产业近年来迅速发展,随着保有量的持续上升,使用环节缺乏专属配套政策、管理标准、产品服务等问题逐步凸显。明确了新能源汽车大数据的定义,剖析了其在智慧监管、汽车金融、保险创新、二手车交易等环节的应用价值及进展,充分分析了当前应用环境并研判未来发展趋势,同时,梳理了行业相关参与者概况及投资机会。研究表明,新能源汽车大数据将在使用端服务方面,逐步形成成熟的商业模式,发挥巨大应用价值。相关投资机会主要包括国家级数据平台及创新中心、地方级数据平台及运营中心、专业类科研院所、智能网联相关科技企业四大类主体。     

微型车正装撑杆背门上移问题分析

针对微型车背门正装撑杆后产生上移的现象,对安装撑杆前、后的现有车型背门进行了理论受力分析,并进行了CAE仿真计算和台架试验。分析表明背门发生上移是由于受到向上的撑杆与锁环限位力的合力所致,且明确了上移量的数值确定方法,可为新车型在设计阶段预留上移量提供理论参考。     

桥梁加铺结构层方案研究

以耒宜高速公路需顶升30.5 cm且跨径为8 m的桥梁为工程背景,拟采用不顶升,直接加铺结构层方式,使之与路面顺接。通过理论计算验证了该方案切实可行,为类似工程提供参考。