多孔介质流动的直接数值模拟

基于计算流体动力学软件Fluent建立了一个二维DNS模型,研究了多孔介质中的流动阻力和压降.模拟时对填充的圆柱粒子采用了2种几何排列方式,即直排和叉排.DNS直排模型的压差为53.5Pa,接近于采用原始系数A=150,B=1.75的尔格方程计算结果55.6Pa.叉排模型的压差为65.1Pa,接近于采用修正系数A=180,B=1.80的尔格方程计算结果62.1Pa.对于真实多孔介质材料的模拟来说,圆柱形粒子叉排比直排更为准确.因此DNS结果确认了修正系数组(A=180,B=1.80)比原始系数组(A=150,B=1.75)更适合尔格方程模型.应用文中推荐的DNS方法,通过采用不同的粒子几何排列方式、填充不同形状的粒子可以进一步地预测尔格方程系数或改善其他的多孔介质模型.     

《城市道路交通规划设计规范》（GB50220—95）中有关指标合理性和取值研究

《城市道路交通规划设计规范》（GB 50220—95）（以下简称GB 50220—95）是城市道路规划的主要依据,对我国城市道路的现状和未来都有重大影响。分析该规范中道路密度与道路面积指标数值的一致性、有关指标与相关规范及实践的协调性对指导实际工作具有一定的意义。     

Optimization of bus rollover strength by consideration of the energy absorption ability

Buses are an integral part of the national transportation system of each country. A rollover event is one of the most important hazards that concerns the safety of the passengers and the crew in a bus. In the past, it was observed after the accident that the deforming superstructure seriously threatens the lives of the passengers. Thus, the stiffness of the bus frame is the first thing that needs to be considered. The unfortunate side of strengthening the bus superstructure is that it usually causes the bus weight to increase. This paper presents an efficient and robust analysis method with which to design the bus superstructure for a reduction in occupant injuries from rollover accidents while the weight of the strengthened bus is maintained at the same level. First, the absorbed energy of the bus frame and its components during a rollover were investigated by using a LS-DYNA numerical study. The highest energy absorption region, which is the side section of the bus frame, was found and focused on for the investigation of a means to re-distribute the energy-absorption ability of the side frame component. Then the thickness parameters that were obtained from the re-distribution of the energy-absorption ability were used in the analysis to optimize the design. Finally, a prototype of the bus with a reasonable thickness for the window pillars and the side wall bars, which was based on the optimized parameters, was verified to ensure it satisfied ECE R66. In this paper, an effective usage of materials and an efficient and robust analysis method were presented to design the bus superstructure. Although the optimization process for increasing the stiffness is simple, this study improves the upper displacement by 39.9% and the lower displacement by 49.3% (versus the bus survivor space) while maintaining the bus weight at the existing level.     

括苍山隧道二号通风竖井正向施工导碴井、二次扩挖法施工技术

No. 2 ventilation shaft of Kuocangshan tunnel on Zhuji Yongjia expressway has complex geologic condition, many construction difficulties and short construction schedule. In order to complete the project on time, the construction technology of "muck dropping shaft sinking and secondary enlarging excavation" is selected for the sinking of the shaft from several shaft sinking methods, including conventional one time shaft sinking method, "muck dropping shaft sinking and secondary enlarging excavation" method and raise boring method. The selected construction technology is presented in this paper. This technology not only achieves good results in construction schedule, construction safety and construction quality, but also reduces the construction cost.     

Eu(DBM)3Phen/PS复合纤维的制备与发光性能

采用静电纺丝法与无皂乳液法相结合制备了稀土配合物/聚合物复合纳米纤维Eu(DBM)3Phen/PS.采用扫描电镜(SEM)、红外光谱(FT-IR)和荧光光谱(FS)等,对纤维的形貌和发光性质进行了表征.实验结果表明,随着PS浓度的增加,所制备的纤维直径逐渐增大,纤维的发光强度也逐渐递增,荧光寿命逐渐增长.     

1种基于车辆时空图的车辆异常行为检测方法

对快速路车辆异常行为的检测有助于防止或及时处理交通事故,缓解交通拥堵,保障出行的安全和效率。采用多高斯背景模型提取前景运动车辆及其中心点并利用Kalman滤波算法跟踪运动车辆。在此基础上,得到各个车道上车辆的行驶时空图,通过车辆时空图对车辆行为进行轨迹分析,根据时间序列上车辆位置的变化检测车辆逆行,通过车间距和车辆位置状态信息检测车辆碰撞。实验表明,该方法能较好地识别出车辆异常行为。     

沥青混合料阻燃性能试验研究

针对隧道沥青混凝土路面火灾的危害,采用锥形量热仪法对沥青混合料SMA13进行阻燃性能评价,其中,沥青胶结料采用了两种阻燃改性沥青和一种非阻燃改性沥青。试验结果表明,沥青混合料在热辐射作用下,短时间内即可引燃,并且释放出大量的热和浓烟(包括有毒气体)。阻燃剂的加入,可延长沥青混合料的引燃时间,对其发热发烟均有明显的抑制作用,可大大提高隧道沥青混凝土路面的安全性。     

轻轨运营事故应急处理模拟演练初探

以重庆市轻轨2号线正式运行前所开展的事故应急处理模拟演练为例,论述城市轻轨运营事故模拟演练工作。总结演练项目选择、方案编制、筹备组织等重要环节的原则、程序及工作要点,并对演练过程中涉及现场展现、公共关系处理等难点问题提出一些解决办法：