民用汽车有望超过3000万辆

据国家统计局统计，2000年我国民用汽车拥有量为1608．91万辆，其中客车为85373万辆。2004年我国民用汽车拥有量增加到269371万辆，客车增加到1735．91万辆。     

汽车有量与年产量的神经网络预测研究

采用神经网络建立汽车保有量与年产量时间序列的预测模型,并对我国未来几年的汽车保有量和年产量进行预测,其中包括民用汽车拥有量、私人汽车拥有量和汽车产量等,取得了较为满意的预测结果.对预测结果进行分析,指出了我国汽车保有量与产量今后发展的特点和趋势.     

汽车保有量与年产量的神经网络预测研究

采用神经网络建立汽车保有量与年产量时间序列的预测模型，并对我国未来几年的汽车保有量和年产量进行预测，其中包括民用汽车拥有量、私人汽车拥有量和汽车产量等，取得了较为满意的预测结果，对预测结果进行分析，指出了我国汽车保有量与产量今后发展的特点和趋势。     

我国汽车拥有量对石油消费量的计量经济模型研究

本文首先建立我国石油消费量与民用汽车拥有量的计量经济模型,利用最小二乘估计的方法得到了石油消费量与汽车拥有量之间关系的估计式,并认为汽车是石油消费主要影响因素。然后进一步利用部分调整模型,以对未来长期的石油储备量进行估计,从而认为汽车数量对石油消费量的影响在长期比近期更大,并说明发展节能汽车的重要性。     

我国民用汽车拥有量今年有望超过3000万

本刊讯 “十五”期间我国汽车产业迅猛发展，国内民用汽车保有量也大幅增加。据权威部门预计，到今年年底我国民用汽车拥有量有望首次超过3000万辆，比“九五”末的2000年净增1400多万辆。     

中国人民保险公司推出新的机动车辆保险条款

1开发背景 随着我国国民经济的快速增长,机动车辆拥有量大幅增加,据公安部统计:截止2001年末全国机动车辆保有量达到685.18万辆,其中民用汽车为184.45万辆,拖拉机191.34万台,摩托车434.21万辆.特别是从1990年到2000年的十年间,我国民用汽车私人拥有量由1990年的81.62万辆增加到2000年的625.73万辆,平均每年增长22.6%,形成了家庭自用、非营业用、营业用三大客户群体.     

上海步行交通规划凸显人性化

截至2006年底，中国私人拥有的各类汽车超过2000万辆。自20世纪80年代中国出现私人小汽车，到2003年其社会拥有量达到1219万辆，私人小汽车突破千万用了近20年，而突破2000万辆仅用了3年时间。据国家统计局统计，截至2005年底．全国民用汽车拥有量为3160万辆，其中私人小汽车达到1852万辆，占总量的58．6％。     

北京市民用汽车495．7万辆

北京市2012年末“全市机动车拥有量520万辆，比上年末增加21．7万辆。民用汽车49517万辆，增加22．5万辆：其中私人汽车407．5万辆，私人汽车中轿车2982万辆，分别增加17．8万辆和12万辆”。这是北京市统计局和国家统计局北京调查总队日前发布的《2012年北京市国民经济和社会发展统计公报》披露的信息，     

信息动态

国家信息中心预测:2009年我国将近1亿人拥有私人小汽车截至2006年底,中国私人拥有的各类汽车超过2000万辆。自20世纪80年代中国出现私人小汽车,到2003年其社会拥有量达到1219万辆,私人小汽车突破千万用了近20年,而突破2000万辆仅用了3年时间。据国家统计局统计,截至2005年底,全国民用汽车拥有     

统一编码是汽配市场发展和行业转型升级的需要

<正>据权威机构统计,截至2013年底,全国民用汽车已达1.37亿辆,每百户城镇家庭的汽车拥有量是21辆。汽车社会的来临,促进了中国汽车后市场的蓬勃发展。目前,全国有机动车维修企业48万家,截至2014年,我国汽车维修配件规模已达1.6万亿元。因此,汽车的保养与维修已成为人们生活中不可或缺的一部分。法典治乱我国汽车后市场发展不够规范,竞争规则不健全,维修技术和配件质量问题频发,因假冒伪劣配件所发生的消费者维权事件     

Evaluation of safety benefits of automatic crash information notification systems on freeways

The automatic crash information notification system (ACINS) is an effective technology to enhance the potential for saving crash victims by reducing the crash response time (CRT) of emergency medical services. Shorter CRT results in a greater potential to save the lives and to alleviate the severity of injuries for crash victims. To fully operate the ACINS, reliable assessments of the safety benefits would be needed for justifying public investment. This study proposed a methodology for quantifying the effectiveness of the ACINS and applied the methodology to the Korean freeway system. The proposed methodology consists of three steps. The first step is to develop a statistical model for predicting injury severity of crash victims using ordered logistic regression. The second step is to estimate the amount of reduced CRT by applying ACINS. The effectiveness of the ACINS, which are defined as the number of reduced fatalities and severe injuries, were evaluated with the consideration of the market penetration rate (MPR) in third step. It has been found that approximately 9.4–15.4% of fatalities can be reduced with 100% MPR when the proposed methodology is applied to 2011 freeway crash data. The outcomes of this study support decision making for public investments and for establishing relevant traffic safety policies.     

Development and validation of a wear model for the analysis of the wheel profile evolution in railway vehicles

The numerical wheel wear prediction in railway applications is of great importance for different aspects, such as the safety against vehicle instability and derailment, the planning of wheelset maintenance interventions and the design of an optimal wheel profile from the wear point of view. For these reasons, this paper presents a complete model aimed at the evaluation of the wheel wear and the wheel profile evolution by means of dynamic simulations, organised in two parts which interact with each other mutually: a vehicle's dynamic model and a model for the wear estimation. The first is a 3D multibody model of a railway vehicle implemented in SIMPACK?, a commercial software for the analysis of mechanical systems, where the wheel–rail interaction is entrusted to a C/C++user routine external to SIMPACK, in which the global contact model is implemented. In this regard, the research on the contact points between the wheel and the rail is based on an innovative algorithm developed by the authors in previous works, while normal and tangential forces in the contact patches are calculated according to Hertz's theory and Kalker's global theory, respectively. Due to the numerical efficiency of the global contact model, the multibody vehicle and the contact model interact directly online during the dynamic simulations.

The second is the wear model, written in the MATLAB® environment, mainly based on an experimental relationship between the frictional power developed at the wheel–rail interface and the amount of material removed by wear. Starting from a few outputs of the multibody simulations (position of contact points, contact forces and rigid creepages), it evaluates the local variables, such as the contact pressures and local creepages, using a local contact model (Kalker's FASTSIM algorithm). These data are then passed to another subsystem which evaluates, by means of the considered experimental relationship, both the material to be removed and its distribution along the wheel profile, obtaining the correspondent worn wheel geometry.

The wheel wear evolution is reproduced by dividing the overall chosen mileage to be simulated in discrete spatial steps: at each step, the dynamic simulations are performed by means of the 3D multibody model keeping the wheel profile constant, while the wheel geometry is updated through the wear model only at the end of the discrete step. Thus, the two parts of the whole model work alternately until the completion of the whole established mileage. Clearly, the choice of an appropriate step length is one of the most important aspects of the procedure and it directly affects the result accuracy and the required computational time to complete the analysis.

The whole model has been validated using experimental data relative to tests performed with the ALn 501 ‘Minuetto’ vehicle in service on the Aosta–Pre Saint Didier track; this work has been carried out thanks to a collaboration with Trenitalia S.p.A and Rete Ferroviaria Italiana, which have provided the necessary technical data and experimental results.     

柴油机伞喷喷嘴内部流动的数值模拟

对柴油机伞喷喷雾及喷嘴内部流动的研究现状进行了分析,利用三维计算流体动力学(CFD)程序对喷嘴内气穴多相流计算模型进行了验证,在此基础上对柴油机伞喷喷嘴内部的流动特性进行了模拟计算分析。结果表明,在伞喷喷嘴喷孔进口处形成不对称的气穴,并逐渐延伸至出口处,从而对燃油雾化产生一定影响。     

斜交板沿横坡的下滑与平面内转动的成因分析

通过建立斜交板在缓慢外爬过程中的几个典型受力模型,并根据前一阶段受力模型的变位及受力结果,给定后一阶段受力模型的边界条件,尝试找到斜交板在间歇性荷载及自重沿横桥向分力的作用下不断外爬,并在平面内转动的成因,发现利用盖梁形成的横坡造成斜板面内的下滑,由下滑导致斜交板沿桥轴向两边约束产生差异,进而诱发斜交板的面内转动。最终模型的变位结果与塘河大桥实桥出现的问题相一致,表明通过建立典型受力模型逐次迭代锁定最终受力状态的方法对于确定斜交板爬移成因是有效的。     

利用Ansys实现拱轴系数m的优化设计

拱桥模型采用板单元模拟实腹段的自重,在Ansys用Qpdl参数化建立拱桥模型。在此模型基础上,使用一阶方法对拱桥的拱轴系数进行优化。通过实例验证了优化程序的正确和高效。     

Heat loss to the combustion chamber wall with deposit in D.I. diesel engine: variation of instantaneous heat flux on piston surface with deposit

Adhesion of deposit on the combustion chamber walls affects the state of the heat loss into combustion chamber wall surfaces in the internal combustion engine. In this study, as the first step, the instantaneous surface temperature and the instantaneous heat flux were measured by thin film thermocouples on piston surfaces in the D.I. diesel engine with the adhesion of deposit in order to clarify the effects of deposit. As a result, it is found that the instantaneous surface temperature and heat flux strongly depend on the amount of deposit adhered to the combustion chamber wall surfaces.     

台阶式格栅加筋挡墙潜在破裂面计算模式研究

基于自洽理论建立了筋土复合材料力学模型,对不同台阶宽度的格栅加筋土挡墙的塑性区进行了有限元分析。研究了其塑性区的发展和贯通过程,对台阶式格栅加筋土挡墙的塑性区分布规律进行了讨论。研究表明,加筋土直墙的塑性区分布接近于0.3H破裂面的假定,但台阶墙的塑性区分布与直墙有显著差异,且随着台阶宽度的变化而变化。提出了适合于不同台阶宽度的格栅加筋土挡墙潜在破裂面的计算模式,当上阶挡墙前趾位于下阶挡墙的主动区内时,该破裂面为一连续曲面;当上阶挡墙前趾位于下阶挡墙的过渡区内时,该破裂面为分段曲面;当台阶宽度为0时,该破裂面可退化为0.3H破裂面。该计算模式具有较好的通用性,能适用于具有不同台阶宽度的加筋土挡墙。     

New nonlinear bushing model for general excitations using Bouc-Wen hysteretic model

Because the characteristics of rubber bushing significantly affect the accuracy of vehicle dynamics simulations, they should be accurately modeled in the vehicle suspension model. In this paper, a new nonlinear bushing model for automotive bushing components is developed to improve the accuracy of vehicle dynamics analysis. Bushing components were first tested to capture the nonlinear and hysteretic behavior of typical elements by using a MTS 3-axis elastomer tester. A simple Bouc-Wen hysteretic differential model was modified to generate a more precise rubber bushing model. A sine wave, step input, and random excitations are imposed on the bushing. The ADAMS program is used to calculate sensitivity and the VisualDOC program is employed to find the optimal parameters for the bushing model. An error function is designed to find optimal parameters of the model. Parameter identification is carried out to satisfy the static and dynamic characteristics due to sine and step excitation inputs. It was proved that the proposed model could predict the bushing forces under sine, step, and random inputs well. The errors are within 10% in the overall range. To show the validity of the proposed model, a numerical example was also carried out. Because the bushing forces due to random excitation input show good agreement with experiments, the proposed bushing model is available in the vehicle dynamics simulation.     

基于GM（1，1）模型的高速公路边坡变形预测

基于边坡变形监测信息具有一定的灰色特征,应用灰色系统理论的原理和方法,建立了边坡变形预测等步长与非等步长GM（1,1）预测模型。采用GM（1,1）模型对衡桂高速公路某典型边坡段测斜管监测变形监测数据进行预测,预测结果与实测结果较为一致,表明了本文建立的灰色预测模型具有较好的可行性和适用性。     

Tractor-semitrailer model for vehicles carrying liquids

This article presents a model for solving solid-fluid interactions in vehicles carrying liquids. A tractor-semitrailer model is developed by incorporating suspension systems and tire dynamics. Owing to the solid-fluid interaction, equations of motion for the vehicle system are coupled. To simplify the complicated solution procedure, the coupled equations are solved separately using two different codes. Each code is analyzed separately; but as the parameters of the two codes depend on each other, the codes must be connected at the end of each time step. To determine the dynamic behavior of the system, different braking moments are applied. As the braking moments increase, braking time decreases. However, it turns out that increasing the braking moment to more than a certain level produces no significant results. It is also shown that vehicles carrying fluids need a greater amount of braking moments in comparison to vehicles carrying solids during braking. In addition, as the level of the fluid inside the tanker increases, from one-third to two-third of the tanker's volume, the sloshing forces applied to the tanker's walls increase. It was also concluded that the strategy used in this article to solve for the solid-fluid interaction by incorporating vehicle dynamic effects represents an effective method for determining the dynamic behavior of vehicles carrying fluids in other critical maneuvers.