基于熵权法的灰色广义模糊神经网络的机动车保有量预测模型

针对机动车保有量作为交通系统的一部分所具有的不确定性和趋势性等特点,通过熵权法确定灰色系统理论和广义模糊神经网络的加权系数来建立组合预测模型,对机动车保有量进行预测。经过实例验证,该组合预测模型与单预测模型相比,能够更准确地预测机动车保有量,与实际值符合较好,可以为有关部门的规划提供可靠的数据依据。     

城市PM2.5治理下机动车保有量研究

在传统 Logistic基础上分析城市机动车保有量和城市PM2.5治理相互关联情况,建立了 Logistic拓展模型来预测城市合适的机动车保有量;以北京市为例,结合近几年相关数据进行模型仿真,得到在P M2.5治理下北京市未来几年机动车保有量合适值。预测结果表明,在 P M2.5治理下,北京市机动车增长速度将有所减缓,到2021年北京市机动车将达到623.9万辆。     

新开发地区机动车保有量预测研究

以现有的地区模型为基础，以规划设计的经济指标为依据对新开发地区的机动车保有量进行预测，提出各机动车分类预测，主要是小客车比较通用的预测方法。     

基于支持向量机的城市私人汽车保有量滚动预测

针对城市私人汽车保有量增长预测问题,在对支持向量机理论进行改进的基础上,进行滚动预测研究。在对已有的机动车保有量预测模型进行对比分析的基础上,建立了基于支持向量机的私人汽车保有量滚动预测模型,并利用北京市私家车保有量历史数据对滚动预测模型进行了实证分析。结果表明该预测模型具有较高的预测精度、符合实际需求、具有广泛的应用前景。     

我国未来汽车保有量情景预测研究

汽车保有量的预测具有一定程度的不确定性。对2010、2020及2030年我国的汽车保有量进行科学预测,是确定我国公路交通长短期发展规划,制定环保与能源等方面相关政策的关键。在对我国经济各个发展阶段进行情景分析的基础上,考虑经济、人口、汽车保有量增长速度以及不同地区人均GDP人群分布等因素,运用趋势外推、弹性系数、国内外情景类比及运输工作量计算等方法对我国未来的汽车保有量进行综合预测,确定到2030年我国汽车保有量将达到2.3~2.5亿辆,是2020年的1.7~1.9倍左右、是2010年的4.6倍。汽车保有量的大幅度增加势必对土地、能源资源和环境保护带来巨大压力,贯彻科学发展观、节约资源、保护环境,走可持续发展道路将是我国未来道路交通发展的客观要求。     

2011年我国摩托车保有量增加260万辆

据公安部交管局统计数据显示，近年来，我国机动车保有量迅速增加，截至2011年6月底，全国机动车总保有量为2．17亿辆，其中摩托车保有量为1．02亿辆。到2011年底，全国机动车保有量达到2．25亿辆，其中摩托车保有量在2011年增加了260万辆。     

公安部发布2008年上半年全国机动车保有量165713347辆

全国汽车、摩托车保有量(截止2008年6月底)机动车保持快速增长,汽车和摩托车是机动车的主要构成部分。全国机动车保有量为165713347辆,与2007年底相比,增加5935758辆,增长3.72%。汽车保有量为61221750辆,与2007年底相比,增加了     

2000年我国轿车市场需求预测

根据我国轿车工业发展的战略要求与现实情况，运用线性回归、弹性系数、趋势外推、市场细分等分析方法，对我国轿车保有量的未来发展趋势及市场需求进行预测。综合分析用上述４种方法预测的结果，认为２０００年我国轿车保有量为４００￣４５０万辆，年需求量达到７５￣８０万辆。通过对轿车产品成本和居民收入影响的分析发展，趋势外推法与弹性系数法，方法简便实用，数据容易取得，但考虑问题单一，易受偶然因素影响，对市场估计过     

中国清洁汽车行动的成就与展望

1中国清洁汽车行动的重要意义 近年来，我国汽车工业得到了快速发展。2004年我国汽车年产量达到507．4万辆，已成为世界第四大汽车生产国和第三大消费国。2004年我国汽车保有量已达到2742万辆，比2003年增长了13％。私人汽车保有量占总保有量的比例已从“九五”末不到40％提高到近60％。摩托车产量和保有量分别达1700万辆和7900万辆。农用运输车产量和保有量分别达200万辆和2500万辆。据有关预测，到2020年我国汽车总需求量将接近2000万辆，总保有量有可能突破1．5亿辆。随着机动车保有量的激增，我国机动车尾气污染问题更显严重，国家环保中心预测，到2010年我国汽车尾气排放量将可能占空气总污染源的64％。     

道路交通伤害与机动车保有量变化的相关性分析

重点研究了经济高速增长期道路交通伤害与机动车保有量之间的关系。通过对中国、美国、日本3个国家各自的经济高速增长期的机动车保有量和道路交通事故死亡人数的全面统计,并且采用双变量相关分析法对两者的变化进行分析,得出了机动车保有量的快速增长与道路交通伤害之间具有显著线性相关性的结论。     

Influence of repeated and delayed excitations in combined subspace identification

The application of combined subspace identification methods to land vehicles would allow the modal parameters of the vehicle to be obtained, while it is in operation, thus improving the vehicle modal characterisation. However, when a land vehicle is circulating through a straight line, the excitations applied to the different axles are identical among them but with a certain time delay. The presence of repeated excitations with different time delays implies that the past and future subspaces include common vectors that may lead to problems in the application of the method. To analyse its influence, an index called the reduction coefficient resulting from excitations (RCE) has been defined. RCE evaluates the amount of information eliminated in the oblique projection due to the effect of repeated excitations. The use of RCE enables the selection of analysis parameters, particularly the sampling frequency, the signals grouping and some specific parameters of the subspace identification methods.     

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.     

车速鉴定中轮胎-路面附着系数估算方法研究

在交通事故鉴定中,车辆行驶速度是事故处理和诉讼的重要依据。其中,路面附着系数是事故车速鉴定的重要参数。本文在大量实验数据基础上,拟合出车辆制动过程的特性曲线,并简化出相应的车速估算模型。利用此模型对不同车型、路面类型、湿滑状况和不同车速情况下的路面附着系数e进行了估算研究。经估算实例验证,文中的估算方法对不同状况下的路面附着系数具有较好的估算能力。     

模数式桥梁伸缩缝水平向动力学响应分析

运用有限元分析软件对模数式桥梁伸缩缝进行水平向动力学研究,建立了其水平向有限元动力学模型,研究了车轮对中梁的水平冲击以及车速、中梁弹性支承刚度及预压量、滑动摩擦系数和剪切弹簧刚度的变化对中梁水平位移的响应特性。研究表明,当车速高于100 km/h,中梁弹性支承刚度小于70 000 N/mm时,应考虑车轮对中梁的水平冲击,当车速低于120 km/h,中梁弹性支承刚度及预压量分别大于80 000 N/mm和0.3 mm,滑动摩擦系数大于0.03,剪切弹簧刚度大于400 N/mm时,此时中梁水平位移小于0.5 mm,且车轮对中梁的水平冲击也可不考虑。     

Estimation of Tire-Road Friction Using Observer Based Identifiers

This paper presents methods for identifying the tire-road friction coefficient. The proposed methods are: an observer-based least square method and an observer/filtered-regressor-based method. These methods were designed assuming that some of the states are not available since physical parameter identification methods developed assuming that the system states are available are not attractive from a practical point of view. The observer is used to estimate signals which are difficult or expensive to measure. Using the estimated states of the system and the filtered-regressor, the parameter estimates are obtained. The proposed methods are evaluated on an eight state nonlinear vehicle/transmission simulation model with a Bakker-Pacejka's formula tire model. Vehicle tests have been performed on dry and wet roads to verify the performance of the methods. It has been shown through simulations and vehicle tests how the RPM sensors can be used with observer based identification methods to estimate the tire-road friction from measurements of engine rpm, transmission output speed and wheel speed. The proposed methods will be useful in the implementation and adaptation of vehicle collision warning/avoidance algorithm since the tire-road friction can be estimated only using the RPM sensors which are currently being used in production vehicles.     

步行车辆运动弹性动力学分析

步行车辆在快速运动中,既有大刚体运动又有小弹性位移,且还有不连续的边界约束条件,是一个很复杂的动力学问题。本文用有限元方法建立了该系统的动力学模型,采用分段的直接积分法求解其弹性动力响应。     

Three-dimensional crush scanning methods for reconstruction of vehicle collision accidents

This paper presents efficient 3-D collision crush modelling methods utilizing photogrammetry and 3-D scanner for reconstruction analysis of vehicle collision accident. Photogrammetry for 3-D collision crush modelling was executed in two methods: Indirect photogrammetry utilizing small amount of preexisting photographic data, and direct photogrammetry utilizing large amount of photographic data collected for the purpose of 3-D modelling. With the 3-D scanner, it was possible to create a more precise 3-D crush model than the photogrammetry method. Using these 3-D crush models constructed with the mentioned methods, several applications in accident reconstruction analysis are presented, based on construction methods and characteristics of the resulting crush model. Indirect photogrammetry produced a 3-D model capable of providing approximate shape of crush with only 2 ~ 3 photos of the damaged vehicle, and made it possible to measure the crush volume for estimating the collision velocity. With direct photogrammetry or 3-D scanner, moving and rotating elaborately built 3-D vehicle deformation models makes it possible to precisely reconstruct the actual collision configuration. Additionally, by elaborately modelling the vehicle and its fragments and then putting them together, it is possible to construct a post-collision model of the whole vehicle.     

Analysis of handling performance based on simplified lateral vehicle dynamics

In this article, the analysis methods for vehicle handling performance are studied. Using simple models, dynamic characteristic parameters such as yaw, natural frequency, and the damping coefficient of a vehicle can be theoretically formulated. Here, the vehicle is simplified by a bicycle (single-track) model, and the tire is modeled by an equivalent cornering stiffness and first order lag. From the experimental road data, the tire model parameters (equivalent cornering stiffness and time lag constant) are extracted. These parameters are then inserted into the theoretically formulated equations of dynamic characteristic parameters. For the purpose of validating the efficiency of the suggested methods, experimental road tests (where the cars have different handling performances) are performed. The results show that vehicle handling performance can be sufficiently represented by the suggested dynamic characteristic parameters. So, it is concluded that the proposed method has practical use for the development of new cars or for the comparison of similar cars since the evaluations of the vehicle handling performance can be efficiently determined by the suggested dynamic characteristic parameters.     

汽车质心位置测试方法的研究

在分析国内外汽车质心位置测试方法的基础上，介绍了采用质量反应法测定汽车质心位置的试验方法，并测试中的主要影响进行了理论分析和试验研究。结果表明，采用质量反应法测定汽车质心位置是完全可行的。     

重载桥梁在混合车列作用下横向分布系数的计算方法研究

针对重载桥梁结构分析中没有"混合车列"作用下横向分布系数计算软件这一情况,对其计算方法进行了研究,并提出了编程加载法、替换法、大荷载法等3种计算方法。以天津临港工业区内的一座重载桥梁为例进行验证,成功地解决了目前主要桥梁软件无法计算混合车列横向加载的问题。详细分析了3种计算方法的特点,确定了各自的适用范围,为同类工程的计算分析提供了参考。