某中型客车进气噪声声学优化

通过对某中型客车空气滤清系统的声场仿真计算和整车进气噪声试验分析,提取其进气噪声声源特性并进行了声学优化。首先采用四负载法提取进气噪声声源特性,建立进气系统声学边界元模型,预测进气系统进气口噪声并与试验测试数据对比,验证提取声源的准确性;然后进行整车进气系统噪声试验,分析进气噪声频谱特性,确定消声频率;最后通过仿真设计了消声元件,并提出优化方案用于实车验证。整车进气噪声试验结果表明,优化后进气系统声学特性得到明显改善。     

广珠通道内旅客出行方式选择行为研究

为了解广珠通道内广珠城轨和公路客运的竞争和合作关系,通过对广珠通道旅客进行SP和RP调查,分析广珠通道旅客出行方式选择行为特征。运用非集计二项Logit模型构建广珠通道内城轨和公路客运客流分担率预测模型,按照加法规则,从经济性、舒适性、安全性、服务质量、快捷性和方便性6个方面构建效用函数。然后,通过该模型计算2014年两种运输方式的分担率分别为50.46%和49.54%,结果显示广珠城轨的开通运营对公路客运的冲击是非常巨大的,直接抢走了公路客运50%的客流量。最后,采用敏感性分析方法探讨公路客运企业的应对措施的效果,预测2015年两种运输方式的分担率分别为47.7%和52.3%,结果显示面对广珠城轨的冲击和竞争,公路客运企业提高自身竞争力的效果是非常有限的。     

对相关规范中有关钻孔桩泥浆性能规定的分析

泥浆性能直接影响钻孔桩的承载力和桩侧摩阻力。讨论分析了建筑和公路桥涵施工规范对泥浆材料和性能指标的规定,指出了泥浆材料和性能指标是与钻孔桩的施工工艺、桩的规格、土层条件以及设计桩侧摩阻力的要求密切相关。     

铁路连续曲梁管道摩阻损失及钢束伸长值的分析计算

针对兰武二线河口南黄河特大桥连续曲梁的张拉施工,分析计算了空间钢束的摩擦损失及伸长值,解决了施工控制中的关键性问题。     

不同层间接触条件下半刚性路面结构疲劳特性分析研究

对半刚性基层沥青路面层间处于完全连续、完全滑动状态条件下的拉应力、剪应力分布进行了分析,同时分析了考虑半滑动半连续状态中不同的滑动系数对沥青层和半刚性层的最大拉应力的影响,并根据我国现行沥青路面设计规范进行了完全连续、完全滑动、半滑动半连续状态下的半刚性基层沥青路面疲劳特性分析。结合湖南省常张高速公路的工程实践,介绍了层间粘接处理的工程经验。     

设计变更条件下的桥梁施工监控及摩阻测试分析

结合义乌江大桥工程实例,论述在设计变更条件下,为实现成桥后桥面线形及结构内力状态符合设计要求,以及保证设计变更前后全桥整体性能,而采取的一系列有针对性的措施,达到了有效的对线形控制和内力监测的目的。对施工中长索单端张拉时钢束实际伸长量与理论伸长量有偏差的问题进行了分析,通过现场摩阻试验, 对分析结果进行了验证,得出了一些有价值的结论。     

损伤梁动力特性的空间有限元分析

以钢筋混凝土梁为研究对象,基于Euler-Bernoulli梁理论和结构动力学理论,考虑混凝土的非线性本构关系,通过空间动力有限元分析,得到不同裂纹状态下梁的固有频率和模态振型,研究裂纹对简支梁振动响应的影响。研究结果表明:损伤结构动力特性对损伤的敏感性并不能简单地归结为对高频一定敏感,对低频一定不敏感,应视裂缝位置与振型节点关系而论。     

Estimation of the tyre–road maximum friction coefficient and slip slope based on a novel tyre model

In this article, a new approach to estimate the vehicle tyre forces, tyre–road maximum friction coefficient, and slip slope is presented. Contrary to the majority of the previous work on this subject, a new tyre model for the estimation of the tyre–road interface characterisation is proposed. First, the tyre model is built and compared with those of Pacejka, Dugoff, and one other tyre model. Then, based on a vehicle model that uses four degrees of freedom, an extended Kalman filter (EKF) method is designed to estimate the vehicle motion and tyre forces. The shortcomings of force estimation are discussed in this article. Based on the proposed tyre model and the improved force measurements, another EKF is implemented to estimate the tyre model parameters, including the maximum friction coefficient, slip slope, etc. The tyre forces are accurately obtained simultaneously. Finally, very promising results have been achieved for pure acceleration/braking for varying road conditions, both in pure steering and combined manoeuvre simulations.     

Comparative study of vehicle tyre–road friction coefficient estimation with a novel cost-effective method

This paper qualitatively and quantitatively reviews and compares three typical tyre–road friction coefficient estimation methods, which are the slip slope method, individual tyre force estimation method and extended Kalman filter method, and then presents a new cost-effective tyre–road friction coefficient estimation method. Based on the qualitative analysis and the numerical comparisons, it is found that all of the three typical methods can successfully estimate the tyre force and friction coefficient in most of the test conditions, but the estimation performance is compromised for some of the methods during different simulation scenarios. In addition, all of these three methods need global positioning system (GPS) to measure the absolute velocity of a vehicle. To overcome the above-mentioned problem, a novel cost-effective estimation method is proposed in this paper. This method requires only the inputs of wheel angular velocity, traction/brake torque and longitudinal acceleration, which are all easy to be measured using available sensors installed in passenger vehicles. By using this method, the vehicle absolute velocity and slip ratio can be estimated by an improved nonlinear observer without using GPS, and the friction force and tyre–road friction coefficient can be obtained from the estimated vehicle velocity and slip ratio. Simulations are used to validate the effectiveness of the proposed estimation method.     

浅议商人的营业行为

从商人的营业的构成、营业的组织样态以及存在形式、营业活动的场所等角度来论证商人营业活动的特色并由此肯定其积极作用,并将这种营业行为定义成一种朴素的营利活动,从而将之上升到商法的本质层面来进行考察,并最终得出结论：商人营业行为的存在有着很深刻的理性因素,商人的营业行为在商法的制度框架内有效的运行是成就“商”这一活动的支柱,更是这个活动存续的重要根基。