A combined use of microscopic traffic simulation and extreme value methods for traffic safety evaluation

This paper proposes a combined usage of microscopic traffic simulation and Extreme Value Theory (EVT) for safety evaluation. Ten urban intersections in Fengxian District in Shanghai were selected in the study and three calibration strategies were applied to develop simulation models for each intersection: a base strategy with fundamental data input, a semi-calibration strategy adjusting driver behavior parameters based on Measures of Effectiveness (MOE), and a full-calibration strategy altering driver behavior parameters by both MOE and Measures of Safety (MOS). SSAM was used to extract simulated conflict data from vehicle trajectory files from VISSIM and video-based data collection was introduced to assist trained observers to collect field conflict data. EVT-based methods were then employed to model both simulated/field conflict data and derive the Estimated Annual Crash Frequency (EACF), used as Surrogate Safety Measures (SSM). PET was used for EVT measurement for three conflict types: crossing, rear-end, and lane change. EACFs based on three simulation calibration strategies were compared with field-based EACF, conventional SSM based on Traffic Conflict Techniques (TCT), and actual crash frequency, in terms of direct correlation, rank correlation, and prediction accuracy. The results showed that, MOS should be considered during simulation model calibration and EACF based on the full-calibration strategy appeared to be a better choice for simulation-based safety evaluation, compared to other candidate safety measures. In general, the combined usage of microscopic traffic simulation and EVT is a promising tool for safety evaluation.     

非平衡等离子体改善柴油机排放的研究

柴油机在应用中,最大的问题是其微粒物和NOx的排放较多,寻找一种可行的技术来实现同时降低其微粒物和NOx已经成为目前柴油机排放研究中急需解决的问题。等离子体技术以其对NOx突出的净化效果成为目前国内外各研究机构的研究重点。本文在通过对等离子体理论及其反应机理进行分析的基础上,采用湿式针板电晕放电反应器结合旋转火花隙开关式高压脉冲电源的试验方案,来探讨非平衡等离子体改善柴油机排放的规律。     

陈毅军事理论研究

陈毅元帅是中国人民解放军的创建人和领导人之一,他在长期的武装革命斗争实践中,创造性地贯彻与执行毛泽东军事思想,不断地总结革命战争的的经验,形成了其丰富的军事理论,为毛泽东军事思想的丰富与发展,作出了重要的理论贡献。     

Internet学习资源在大学英语听说教学中的有效性研究

本文采用问卷调查和实证研究,以90名学生为研究对象,运用建构主义学习理论,阐述Internet学习资源有效融入听说教学中的关键,在运用网络资源和计算机辅助英语教学的过程中要全面激发学生学习英语的兴趣,并对研究结果做出了相应的探讨。     

基于目的论的好莱坞电影片名翻译策略初探

全球化趋势下,好莱坞电影作为美国大众文化代表在世界范围内流行,不仅创造了巨大的经济利益,而且传播了美国文化。能够令国人接受和理解的片名翻译对影片的成功也显得尤为重要,本文以目的论为理论依据对好莱坞电影片名翻译应考虑的要素和常见的翻译方法进行初步的探究,并对译者的要求提出若干建议。     

《道桥材料试验检测》课程“理实一体化”教学模式探究

在《道桥材料试验检测》课程的教学实践中,采用"理实一体化"的教学模式,是加强学生试验检测技能,提高教学质量,促进就业的有效途径。本文介绍了该课程的设计思路、课程标准、教学模式、教学方法与手段以及考评等相关内容与实施过程。     

用科学发展观统领铁路工作深入推进铁路跨越式发展为我国经济社会又快又好发展做出更大贡献--在全国铁路工作会议上的报告(摘要)

“十五”期间铁路工作取得了巨大成就。铁路跨越式发展取得了显著成绩:运输生产经营跃上新台阶;实施《中长期铁路网规划》取得重大进展;技术装备现代化迈出重要步伐;铁路内部改革取得了历史性的突破;铁路运输安全保持了基本稳定。“十一五”我国经济社会发展将切实转入科学发展轨道,落实科学发展观,构建社会主义和谐社会和建设资源节约型、环境友好型社会将进入新的阶段,铁路的作用将更加突出。实现“十一五”铁路跨越式发展的目标,无论是路网规模、运输能力、现代化水平,还是服务质量,都将有一个很大的提升。     

论邓小平对马克思主义教育政治学思想的继承与发展

邓小平教育政治学思想是马克思主义教育政治学思想体系中的有机组成部分．邓小平对教育在国家发展中的定位、加强党对教育的领导、教育改革与教育民主化以及教育在政治社会化中的作用等诸多方面继承与发展了马克思主义的教育政治学思想，形成其独具特色的教育政治学思想体系．     

Short-Term Traffic Flow Forecasting for Freeway Incident-Induced Delay Estimation

Freeway incidents not only threaten travelers’ safety but also cause severe congestion. Incident-induced delay (IID) refers to the extra travel delay resulting from incidents on top of the recurrent congestion. Quantifying IID would help people better understand the real cost of incidents, maximize the benefit-cost ratio of investment on incident remedy actions, and develop active traffic management and integrated corridor management strategies. By combining a modified queuing diagram and short-term traffic flow forecasting techniques, this study proposes an approach to estimate the temporal IID for a roadway section, given that the incidents occurs between two traffic flow detectors. The approach separates IID from the total travel delay, estimates IID for each individual incident, and only takes volume as input for IID quantification, avoiding using speed data that are widely involved in previous algorithms yet are less available or prone to poor data quality. Therefore, this approach can be easily deployed to broader ranges where only volume data are available. To verify its estimation accuracy, this study captures two incident videos and extracts ground-truth IID data, which is rarely done by previous studies. The verification shows that the IID estimation errors of the proposed approach are within 6% for both cases. The approach has been implemented in a Web-based system, which enables quick, convenient, and reliable freeway IID estimation in the Puget Sound region in the state of Washington.     

帽型、点焊薄壁柱壳轴向挤压性能分析

在M D White和N Jones等人的研究基础上,充分考虑柱壳被挤压变形时塑性铰吸能,将其求解过程中的离散单元的数目由18个增至19个,进而使吸能和平均压塌力控制方程更接近试验实际情况。给出柱壳被挤压时平均压塌力的理论计算算例,并用LS DYNA软件对建立的帽型、点焊薄壁柱壳轴向挤压过程力学模型进行了数值模拟。计算结果显示,该结构撞击变形过程相对稳定,与修正的吸能和平均压塌力控制方程计算结果很接近;与M D White和N Jones等人的试验结果进行对比分析,证实帽型、点焊薄壁柱壳具有良好的能量吸收性能。