高速公路汽车追尾预警系统的开发研究

对高速公路汽车追尾预警系统进行了总体设计,把系统划分为主控单元、雷达测距单元、信息采集单元、显示-声光报警单元4个子系统。在分析汽车动力学基础上,提出了系统安全距离模型,并对各子系统进行了软、硬件设计。通过模拟试验和实际装车实验,验证了系统所要求的各种性能,雷达测距准确,系统报警及时有效.     

城市交通与环境可持续发展指标体系评估系统研究——上海案例应用

可持续发展是一种将社会发展概念从单纯经济增长拓展到经济、社会、环境协调发展的城市发展新模式.交通环境的可持续发展在整个发展体系中占据着重要地位.本文针对目前大城市普遍面临的交通环境压力和经济、交通与环境系统的复杂性,通过构建经济-交通-环境间的压力与响应关系,建立了可用于"回顾过去、解析现状、瞻望未来"的城市交通环境可持续发展指标体系.采用隶属函数对单项指标进行标准化处理,对交通环境可持续发展综合指数的评价,采用层次分析法确定各指标的权重.采用Visual Basic 6.0及Office的Access 2000,开发了交通环境可持续发展指标体系评估系统,并以上海市为案例进行了研究.本系统的开发可为城市交通环境可持续状况评价及发展对策的制定提供技术支持.     

Investigating the effectiveness of safety countermeasures at highway-rail at-grade crossings using a competing risk model

Introduction: Highway-rail at-grade crossings (HRGCs) are critical locations where a railway and a roadway intersect with one another. Crashes at those locations often result in fatalities and economic and social damages due to the impacts on both road and rail users. The main purpose of countermeasures at HRGCs is to permit safe and efficient rail and highway operations. Method: Countermeasures at highway-rail grade crossings (HRGCs) considered in this study include all traffic control devices and other warning and barrier devices at or on approaches to crossings. In general, active devices are commonly accepted as more effective countermeasures than passive devices. However, many of the previous effectiveness studies are either at the project level or were conducted without considering the before-improvement condition. This study focuses on the network-level marginal effectiveness of countermeasures on crash rate and severity levels during the 29-year study period from 1990 to 2018 by fully considering before-improvement control levels. A competing risk model (CRM) is able to accommodate the competing nature of crash severities as multiple outcomes from the same event of interest, which is crash occurrence in this study. Subsequently, CRM is used in this study as an integrated one-step estimation approach that investigates both crash frequency and severity likelihood over time. Results: The study findings indicate that adding audible devices to crossings already equipped with gates will result in a considerable annual decline in crash occurrence likelihood (0.25%). The same device installed at crossings already controlled by gates and flashing lights results in less reduction in crash occurrence likelihood of 0.14%. Moreover, adding a stop sign to the active crossing controls of gates, standard flashing lights, and audible devices will lead to a decrease in the probability of crash occurrence and severe crashes (injury and fatal). However, adding stop signs to crossings equipped only with crossbucks will increase the crash occurrence.     

鄂尔多斯市城市道路交通噪声的现状分析及防治对策——以东胜区为例

通过分析鄂尔多斯市2007—2010年东胜区道路交通噪声污染现状,指出存在的主要问题,提出了相应的污染控制及防治措施,为有效改善城市道路交通噪声污染提供科学依据。     

江苏省声环境质量二十年演变规律及污染防治措施

综合分析1991年至2010年声环境质量二十年演变规律,得出环境噪声在污染治理方面所采取和措施     

锦州市交通污染现状与趋势分析

通过对近10年数据的统计分析,掌握锦州市交通污染现状,并对今后的污染趋势进行了分析.     

锦州市道路交通噪声污染状况及防治对策

在对锦州市道路交通噪声10多年来监测数据统计的基础上,从分析所在城市交通噪声的污染现状入手,讨论其污染成因,并提出控制与削减城市交通噪声污染的对策和建议。     

含信号控制人行横道的街道峡谷污染物扩散三维数值模拟

耦合微观交通仿真和机动车尾气排放模型,分别对含信号控制人行横道和不含信号控制人行横道的街道峡谷污染物排放进行计算,并以此为排放源,采用k-ε两方程模型与组分输运方程对风向与街道垂直时的污染扩散情况进行了三维数值模拟.结果表明,k-ε两方程模型与组分输运方程可以较好地模拟风向与街道垂直时三维街道峡谷内的污染物扩散情况.峡...     

Source attributions of heavy metals in rice plant along highway in Eastern China

Air and soil pollution from traffic has been considered as a critical issue to crop production and food safety, however, few efforts have been paid on distinguish the source origin of traffic-related contaminants in rice plant along highway. Therefore, we investigated metals (Pb, Cd, Cr, Zn and Cu) concentrations and stable Pb isotope ratios in rice plants exposed and unexposed to highway traffic pollution in Eastern China in 2008. Significant differences in metals concentrations between the exposed and unexposed plants existed in leaf for Pb, Cd and Zn, in stem only for Zn, and in grain for Pb and Cd. About 46% of Pb and 41% of Cd in the grain were attributed to the foliar uptake from atmosphere, and there were no obvious contribution of atmosphere to the accumulations of Cr, Zn and Cu in grain. Except for Zn, all of the heavy metals in stem were attributed to the root uptake from soil, although significant accumulations of Pb and Cd from atmosphere existed in leaf. This indicated that different processes existed in the subsequent translocation of foliar-absorbed heavy metals between rice organs. The distinct separation of stable Pb isotope ratios among rice grain, leaf, stem, soil and vehicle exhaust further provided evidences on the different pathways of heavy metal accumulation in rice plant. These results suggested that further more attentions should be paid to the atmospheric deposition of heavy metals from traffic emission when plan crop layout for food safety along highway.     

高架道路交通噪声动态模拟

为研究高架道路噪声的分布规律,结合微观交通仿真、车辆噪声排放和传播原理,对高架道路交通噪声进行动态模拟.该方法能得到逐秒变化的实时声压级.能反映交通噪声随时间的动态变化,且方便应用多项指标评估.研究表明:等效声级和累计声级的误差达到±2 dB;高架道路两端的防撞护栏在离道路边缘32m的垂直面上的声压衰减影响到10m左右...