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本文通过对国道345线杂多-查旦乡-查吾拉段公路沿线多年冻土地质情况的现场踏勘,依据踏勘结果分析,初步估计了该路段沿线多年冻土分布情况及主要特征,为沿线多年冻土勘察设计提供基础依据,并为路线设计提供理论参考。 相似文献
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广东省罗阳高速公路石主隧道为双连拱隧道,其位于溶岩发育区,地质情况复杂,施工难度大。以石主隧道为工程依托,介绍双连拱隧道在溶岩发育地质段的施工技术,总结溶岩地区双连拱隧道在施工过程中的综合超前地质预报、突泥涌水处理、中导坑及主洞溶洞处理等关键技术,为溶岩地区双连拱隧道设计和施工提供参考。 相似文献
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为了解驾驶员在汽车碰撞瞬间的颈部肌肉主动反应,在汽车性能模拟器上构造了具有高度虚拟现实感的汽车正碰工况,选择10名志愿者在模拟器上分别以20、50、80和100km/h时速驾驶,记录在碰撞发生时驾驶员胸锁乳突肌、头夹肌和斜方肌的肌肉电信号及其肌肉激活程度。实验结果表明,发生碰撞时,驾驶员主要工作肌群的肌肉电信号明显升高,同时,肌电信号增幅随着车速升高呈现整体增大态势。本研究揭示了汽车碰撞时驾驶员颈部肌肉力学特性的动态变化规律,为高仿生保真度的假人模型的建造和更为准确地分析乘员碰撞损伤提供了理论支撑。 相似文献
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发动机能量利用率是一种分析和评价燃油经济性匹配水平的方法。首先计算出NEDC工况试验时为克服行驶阻力所做的功,再通过NEDC工况试验得出实际油耗,并将油耗转化为完全燃烧所释放的能量。将克服行驶阻力所做功除以完全燃烧释放的能量便是该车型NEDC工况试验时的能量利用率。能量利用率可用于判断开发车型与竞争车型经济性匹配水平的优劣,也可用于判断不同级别车型经济性匹配水平的优劣。 相似文献
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Oblique ocean wave damping by a vertical porous structure placed on a multi-step bottom topography is studied with the help of linear water wave theory. Some portion of the oblique wave, incident on the porous structure, gets reflected by the multi-step bottom and the porous structure, and the rest propagates into the water medium following the porous structure. Two cases are considered: first a solid vertical wall placed at a finite distance from the porous structure in the water medium following the porous structure and then a special case of an unbounded water medium following the porous structure. In both cases, boundary value problems are set up in three different media, the first medium being water, the second medium being the porous structure consisting of p vertical regions-one above each step and the third medium being water again. By using the matching conditions along the virtualvertical boundaries, a system of linear equations is deduced. The behavior of the reflection coefficient and the dimensionless amplitude of the transmitted progressive wave due to different relevant parameters are studied. Energy loss due to the propagation of oblique water wave through the porous structure is also carried out. The effects of various parameters, such as number of evanescent modes, porosity, friction factor, structure width, number of steps and angle of incidence, on the reflection coefficient and the dimensionless amplitude of the transmitted wave are studied graphically for both cases. Number of evanescent modes merely affects the scattering phenomenon. But higher values of porosity show relatively lower reflection than that for lower porosity. Oscillation in the reflection coefficient is observed for lower values of friction factor but it disappears with an increase in the value of friction factor. Amplitude of the transmitted progressive wave is independent of the porosity of the structure. But lower value of friction factor causes higher transmission. The investigation is then carried out for the second case, i.e., when the wall is absent. The significant difference between the two cases considered here is that the reflection due to a thin porous structure is very high when the solid wall exists as compared to the case when no wall is present. Energy loss due to different porosity, friction factor, structure width and angle of incidence is also examined. Validity of our model is ascertained by matching it with an available one. 相似文献
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This study develops a car‐following model in which heavy vehicle behaviour is predicted separately from passenger car. Heavy vehicles have different characteristics and manoeuvrability compared with passenger cars. These differences could create problems in freeway operations and safety under congested traffic conditions (level of service E and F) particularly when there is high proportion of heavy vehicles. With increasing numbers of heavy vehicles in the traffic stream, model estimates of the traffic flow could be degrades because existing car‐following models do not differentiate between these vehicles and passenger cars. This study highlighted some of the differences in car‐following behaviour of heavy vehicle and passenger drivers and developed a model considering heavy vehicles. In this model, the local linear model tree approach was used to incorporate human perceptual imperfections into a car‐following model. Three different real world data sets from a stretch of freeway in USA were used in this study. Two of them were used for the training and testing of the model, and one of them was used for evaluation purpose. The performance of the model was compared with a number of existing car‐following models. The results showed that the model, which considers the heavy vehicle type, could predict car‐following behaviour of drivers better than the existing models. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献