Recursive estimation of average vehicle time headway using single inductive loop detector data

Vehicle time headway is an important traffic parameter. It affects roadway safety, capacity, and level of service. Single inductive loop detectors are widely deployed in road networks, supplying a wealth of information on the current status of traffic flow. In this paper, we perform Bayesian analysis to online estimate average vehicle time headway using the data collected from a single inductive loop detector. We consider three different scenarios, i.e. light, congested, and disturbed traffic conditions, and have developed a set of unified recursive estimation equations that can be applied to all three scenarios. The computational overhead of updating the estimate is kept to a minimum. The developed recursive method provides an efficient way for the online monitoring of roadway safety and level of service. The method is illustrated using a simulation study and real traffic data.     

A model for the visualization and analysis of elevator traffic

ABSTRACT

Analysis of elevator traffic in high rise buildings is critical to the performance evaluation of elevator group control systems (EGCS). Elevator dispatching methods or parking algorithms in an EGCS can be designed or modified according to analyses of traffic flow. However, interpretation of traffic flow based solely on numerical data may not be explicit and transparent for EGCS experts as well as for other non-expert building administration. In this study, we present a model for visualization and analysis of elevator traffic. First, we present an alternative approach for traffic analysis which we call route visualization. In the proposed approach, we initially decompose elevator traffic into its component parts and investigate each component independently. Then, using superposition of components we obtain a reconstructed model of overall traffic. This modeling approach provides component-based traffic analysis and representation of routes with intensities through data visualization. In the second part we introduce a multi-dimensional analysis of time parameters in ECGS. This approach provides a comparative analysis of several control algorithms such as dispatch or park algorithms for different combinations of traffic components.     

A field evaluation case study of the environmental and energy impacts of traffic calming

This study quantifies the energy and environmental impact of a selection of traffic calming measures using a combination of second-by-second floating-car global positioning system data and microscopic energy and emission models. It finds that traffic calming may result in negative impacts on vehicle fuel consumption and emission rates if drivers exert aggressive acceleration levels to speed up to their journeys. Consequently by eliminating sharp acceleration maneuvers significant savings in vehicle fuel consumption and emission rates are achievable through driver education. The study also demonstrates that high emitting vehicles produce CO emissions that are up to 25 times higher than normal vehicle emission levels while low emitting vehicles produce emissions that are 15–35% of normal vehicles. The relative increases in vehicle fuel consumption and emission levels associated with the sample traffic calming measures are consistent and similar for normal, low, and high emitting vehicles.     

马尔柯夫灰色残差模型在剐构桥控制中的应用

文章结合罗天乐特大桥的马尔柯夫灰色残差模型预测实例,介绍马尔柯夫灰色残差模型在线性控制中的原理、计算及应用过程,并根据实际监控经验提出了建议。罗天乐特大桥的具体监控应用实践表明,马尔柯夫灰色残差模型预测精度高,能较好地应用于大跨连续刚构桥的施工线形控制。     

人的可靠性分析方法及其在军事活动中的应用

回顾了人的可靠性分析发展的历史和现状,重点对现在已存在的人的可靠性分析方法进行了介绍分析,提出并简要介绍了两种在军事活动中适用的人的可靠性评估方法的基本原理：基于粗糙集的人的可靠性评估法和基于贝叶斯的人的可靠性评估法,最后分析了人的可靠性研究中存在的问题。     

一种螺旋桨参数化建模方法

对螺旋桨进行优化时,需要建立起优化计算的样本空间,即要实现初始桨的参数化建模。本文基于贝塞尔曲线拟合原理编程实现了螺旋桨的参数化建模,对螺旋桨的径向参数分布分别用一条贝塞尔曲线进行拟合,曲线的控制点通过遗传算法寻优求得。文中以4382桨为例,对其进行参数化建模,讨论了三、四、五、六阶贝塞尔曲线的拟合效果,发现三阶贝塞尔曲线拟合光顺性最好、拟合平均误差可以控制在0.3%以内,而且控制点个数较少,最适合拟合螺旋桨径向参数分布。最后通过调整三次贝塞尔曲线控制点的位置调整了原桨叶的几何形状,得到光顺性较好的新桨叶模型,表明该参数化建模方法合理。     

海员胜任力结构及其评价标准初步研究

对129名海员进行了5项6个心理指标的测试。通过专家咨询法确定海员胜任力检测指标体系的权重系数，构建了海员胜任力特征结构模型与综合评价模型。提出了40岁以下和以上年龄海员的胜任力评价标准。     

台州港临海港区规划波浪潮流泥沙数学模型研究

文章研究了台州港临海港区规划围垦后的有关潮流泥沙问题。首先对该海区的自然条件进行了分析,而后使用二维波浪潮流泥沙数学模型研究手段对台州港规划围垦后的二维潮流场、泥沙场、地形冲淤变化进行了模拟研究。研究结果表明,从周围水沙环境的影响考虑,该港区规划围垦的方案是可行的。     

基于Simulink/Stateflow的汽车ABS混合建模与仿真

汽车防抱死制动系统(ABS)是一种很关键的汽车主动安全技术。本文采用基于有限状态机的系统仿真方法,采用Simulink和Stateflow模块混合建模,对ABS模型中的连续系统和离散系统进行仿真。仿真结果表明,该混合仿真系统能比较真实地反映汽车ABS系统的实际工作过程,显著缩短制动距离,提高安全性。     

Rhinoceros软件在客车造型设计中的应用

介绍造型设计软件Rhinoceros,并以豪华大客车为例,讲述该软件在客车CAS(计算机辅助造型设计)中的应用。