Are we successful in reducing vehicle miles traveled in air quality nonattainment areas?

An important planning and policy question in the transportation, energy, and environment areas is whether or not air quality control and the associated funding preference and mitigation efforts to attain air quality conformity have indeed led to traveler behavior changes such as reduction in vehicle miles traveled (VMT) or VMT growth rates. In this research, we develop statistical models to analyze the relationship between air quality nonattainment designation and VMT between 1966 and 2004 based on observed data. These models employ different statistical methods, including hypothesis testing and simultaneous equations. Findings from these statistical models and datasets are consistent, and suggest there is a statistically significant negative correlation between nonattainment designation and VMT/VMT growth. For instance, the simultaneous equation model in this research, suggests that if a nonattainment area and an attainment area that are similar in all other aspects (population composition, socio-economics, urbanization, fuel price, vehicle stock, etc.) are compared, the VMT in the nonattainment area will be 1.80% less than that in the attainment area in the short run, and 7.61% less in the long run. While these results show strong statistical evidence that efforts in reducing VMT in nonattainment areas have been successful, future research should be conducted to attribute the VMT reduction effects to specific policy instruments for decision-making (e.g. the Congestion Management and Air Quality Improvement program, the conformity regulation in the transportation planning process, etc.).     

铁路桥梁摇轴支座铰轴窜出病害机理

针对京广铁路特大桥部分区段出现的支座病害，分析归纳了桥梁支座病害的几种主要形式，探讨铁路桥梁支座横窜成因的理论和解决方案．采用车桥耦合数值模拟方法进行动力分析，对支座的局部受力性能采用有限元模拟分析，找出诱发铰轴横向窜出的主要因素及其对列车运行的不利影响，为减轻铰轴横向窜移病害及支座的改进设计提供依据．     

油船结构强度设计和审图要点

以32万t超大型油船为例,参照国际船级社协会油船共同结构规范的要求,对油船的结构强度设计作了详辟研究,并提出了油船结构审图中规范校核以及有限元分析时,包括屈服、屈曲、疲劳等方面应注意的问题。     

江海通航散货船波浪载荷研究

采用ISSC二参数波浪谱和E1海区的波浪散布图对江海通航散货船的波浪载荷进行了长期预报,并与CCS海船规范和IACS散货船共同规范(CSR)中的设计波浪载荷进行了比较分析,拟合出了应用于江海通航船舶有限元分析的等效设计波高公式.研究表明:江海通航散货船的波浪载荷中垂向弯矩较无限航区海船规范值可降低20%～25%,波浪垂向剪力比《内河航行海船建造海规》规范值增大4%～8%,非常接近CSR规范值,水平波浪转矩比CSR规范值小18%～30%,波浪转矩比CSR规范值则要降低27%～33%.     

薄膜型液化天然气船结构规范计算的比较和研究

基于某22万m3薄膜型液化天然气船,比较了ABS、DNV和LR船级社对薄膜型液化天然气船的结构规范异同点,着重讨论了液货舱周界的腐蚀厚度、规范计算等技术问题,并探讨了薄膜型液化天然气船在局部支撑构件尺寸统一要求方面的可行性。     

新疆宽浅变迁性河流特性初探

基于现场观测和实地调研,分析了新疆宽浅变迁性河流的水流泥沙特性,阐述了宽浅变迁河流的变迁特点.结果表明新疆宽浅变迁河流具有流量小、坡陡流急、床沙粒径较粗、含沙量大、冲淤变化快、变迁明显等特点,与内地河流相比存在显著的差异,这对新疆桥涵设计及河流整治具有一定的理论和实践指导意义.     

宽浅变迁性河段桥长计算公式比较分析

文章以新疆宽浅变迁性河段现行桥长计算公式为基础,通过建立桥长模型公式与实桥的比较分析,选出适用于新疆宽浅变迁河段水流泥沙运动特性的桥长计算公式。     

交通安全、交通效率与交通行为选择

从现存城市道路交通安全隐患的社会背景出发,指出出行者现代交通意识和交通行为选择的特别重要性,给出了现代交通意识与交通安全内涵的科学概括,分析了认识城市道路交通属性与现代交通意识的关系,举例说明了交通行为选择中的若干心理学问题,简要论述了交通伦理、交通法治在建立和谐社会、和谐交通中的重要意义。     

广西高等级公路交通噪声预测值的衰减规律的研究

文章根据广西高速公路目前车流量、车型比以及车速情况,结合交通环境噪声的实测数据,对高速公路交通噪声的变化规律进行分析研究。     

三轴压缩条件下裂隙性黄土的变形特征

通过对裂隙性黄土样的侧壁标记网格,量测、描述了不同含水量、不同裂隙空间形态的土样在不同试验围压下经过三轴压缩后的变形及其特征,总结了其变形规律。试验结果显示,裂隙性黄土的整体变形分为轴向变形、弯曲变形、旋转变形和扭转变形4种方式,其变形方式与土样的含水量、原裂隙的空间形态及性质、试验围压等因素密切相关,土样的变形方式决定了土样的破坏方式。