Development of analytical procedure for selection of control measures to reduce congestions at various freeway bottlenecks

Variable speed limit (VSL) and ramp metering (RM) affect freeway traffic operations in different ways and, accordingly, result in different effects on system travel time. The primary objective of this study is to propose an analytical procedure to help determine which control measure should be selected given different freeway bottlenecks and traffic conditions. The bottlenecks considered included an isolated merge bottleneck, a merge bottleneck with a closely spaced upstream off-ramp, and a diverge bottleneck with a closely spaced upstream on-ramp. Two RM and a VSL control strategies were considered, including the ALINEA, ALINEA/Q and feedback based VSL. The maximum achievable improvements in system efficiency by various control measures were calculated and the results were tested using modified cell transmission models. A coordinated control strategy that combined ALINEA/Q and VSL control was also proposed. The effects of VSL and RM control on system travel time at different freeway bottleneck areas were compared to identify the applicable conditions of different control measures. The analytical procedure was proposed for the selection of control measures at different bottlenecks and the ex-ante estimation of control effects were also discussed.     

Numerical Analysis of the Mixture Formation in a Two-Stroke Wall-Guided LPG DI Engine for Extended-Range Electric Vehicle

The use of automotive LPG characteristics which are easy to evaporate vaporization and carry. The paper presents a design of extended-range electric vehicle for wall-guided two stroke LPG engine with direct injection combustion system. Based on the modified vehicle LPG spray model, a database describing the characteristics of vehicle LPG fuel was built and imported into the CFD software. And the accuracy of the model is verified by the Schlieren experimental results. The concentration and velocity field of the mixture in the cylinder under different load conditions are numerically analyzed. The analyzed result indicated that the start injection time θ = 60°–70°CA BTDC under part load condition, the plug electrode near the gathering of a richer mixture is easy to be fired at spark ignition time, the obvious formation of mixture in cylinder is formed and the overall air-fuel ratio is above 40: 1. The start-transition working condition and large load conditions in the piston moves upward before closing the exhaust port to start injection LPG. The optimized LPG injection start time θ ensures that the fresh gas is locked in the cylinder when the exhaust port is closed (63°CA ABDC). In the ignition time of the spark plug, an ideal homogeneous mixture in the cylinder is realized.     

评价重型车用柴油机排放的13工况测试循环和欧洲稳态测试循环的对比

基于同一组增压中冷重型车用柴油机排放试验数据，采用拟合插值的方法得到了13工况循环和欧洲稳态循环两种不同测试循环的比排放数据。利用分担率和加权比排放数据分析了上述两种测试循环的不同点。指出了在实行欧Ⅲ排放法规后对车用柴油机进行排放优化的策略。     

智能车辆机器视觉发展近况

简要回顾了机器视觉的早期发展，从简单的特定场合应用到模拟人眼的复杂系统设计，介绍了机器视觉产品在智能汽车上的应用情况，分析了世界各国在车用机器视觉技术领域研究开发情况以及未来发展趋势。     

单边索斜塔钢-混凝土结合梁斜拉桥塔梁根部应力分析

采用板 (壳 )、梁及三维实体单元相结合 ,对长沙市浏阳河洪山庙大桥塔梁根部区域进行空间有限元分析。分析表明 :主梁根部过渡段钢箱梁及混凝土的应力满足规范的限值要求 ,行车道板的剪力滞效应明显 ,徐变对主梁应力的分布影响显著 ;塔根部混凝土在施工过程及运营阶段均处于全截面受压状态 ,与试验结果相比较 ,吻合良好     

柴油、乳化油和甲醇喷雾燃烧光强波的研究

探讨了柴油机燃烧光强波的性质。在不同压力、氧浓度的条件下，对柴油、乳化油、甲酵喷雾的燃烧光强波进行了测量分析。结果表明，柴油机的燃烧光强波所反应的是火焰内碳粒的氧化历程。对于不同的燃料，燃烧光强波的强弱并不仅仅取决于火焰中碳粒的数量，同时还取决于火焰中的氧浓度。     

振冲碎石桩在软土地基处理中的应用

结合工程实例 ,对振冲碎石桩加固软土地基的机理加以分析。     

喷锚支护的时间效应与空间效应

喷锚支护是新奥法构筑隧道的主要支护手段，为使喷锚支护与围岩形成共同承载结构，必须在适宜的时机及根据适当的围岩变位量来确定恰当的喷锚支护结构。     

基于决策偏好的ETC系统评价指标体系及评价方法

为更好地反映不同决策者对电子收费系统（ETC）评价的偏好,从政府、运营者和付费者三个主要利益主体的角度对ETC系统的评价指标及评价方法进行了研究。根据评价指标体系筛选原则,确定了基于决策偏好的ETC系统评价指标体系;通过综合分析成本-效益法（CBA）和数据包络分析法（DEA）的各自特点,依据基于决策偏好所确定的评价指标,同时引入当前一些比较好的算法来优化CBA,DEA和AHP法,建立数学模型,从而确立了基于决策偏好的综合评价方法。该方法较为全面地对ETC系统社会经济影响进行评价,所建立的指标体系和方法能更直观、更可靠地反映出决策者的决策偏好。     

农村公路建设中低造价路面结构的尝试

主要针对农村公路建设中降低路面结构造价,解决地方资金筹措的问题所做的一些尝试。