客车图案设计方法与应用

简述图形设计、色彩设计理论以及在客车图案、色彩设计中的应用     

Meta-analysis of UK values of travel time: An update

Numerous travel demand studies have been carried out over the past five decades, many of which produce estimates of the value of travel time. This includes a rich body of largely unpublished evidence, which can provide valuable insights into the impact of variables such as GDP, travel distance, purpose and mode on this critical parameter for transport modelling and appraisal. The work reported in this paper updates and extends our previous meta-analyses of UK values of time ( [Wardman, 1998], [Wardman, 2001a] and [Wardman, 2004]) by adding recent studies and widening the range of explanatory variables included. Our current research covers 226 studies carried out between 1960 and 2008, yielding a total of 1749 valuations (a 50% increase relative to our previous work) and making this the largest data set of its kind to the best of our knowledge. This is also the most comprehensive study to date of parameters other than in-vehicle time and includes valuations of walk, wait, headway, congested, free flow, late, departure time shift and search time. Exploratory analysis of the data set provides interesting insights into methodological trends in travel demand modelling.For each valuation, over thirty quantitative and categorical variables were recorded and then included in a multivariate regression model to explain variations in the value of time. A large number of statistically significant effects were obtained from this meta-analysis, some of which are in marked contrast with, or not present in, our previous work. One finding that stands out is that the estimated elasticity of the value of time with respect to GDP per capita is 0.9 and highly significant, a much closer correspondence to the widely used convention of a unit income elasticity over time than we have previously obtained. The ratio between walk and wait time and in-vehicle time was found to be substantially lower than the commonly used value of two. We also found large and significant differences between the results from studies based on different types of Stated Preference survey presentation. Other important effects include variations by mode used, mode valued, travel purpose, attribute type and distance. It is envisaged that the results are of direct relevance in the British context, as inputs to appraisal or for benchmarking, whilst the methodological implications are of broader interest and the results, in terms of time equivalents and variations in values of time, can be transferred to other contexts.     

Non-linear modelling and control of semi-active suspensions with variable damping

Electro-hydraulic dampers can provide variable damping force that is modulated by varying the command current; furthermore, they offer advantages such as lower power, rapid response, lower cost, and simple hardware. However, accurate characterisation of non-linear f–v properties in pre-yield and force saturation in post-yield is still required. Meanwhile, traditional linear or quarter vehicle models contain various non-linearities. The development of a multi-body dynamics model is very complex, and therefore, SIMPACK was used with suitable improvements for model development and numerical simulations. A semi-active suspension was built based on a belief–desire–intention (BDI)-agent model framework. Vehicle handling dynamics were analysed, and a co-simulation analysis was conducted in SIMPACK and MATLAB to evaluate the BDI-agent controller. The design effectively improved ride comfort, handling stability, and driving safety. A rapid control prototype was built based on dSPACE to conduct a real vehicle test. The test and simulation results were consistent, which verified the simulation.     

并行工程在汽车车身开发上的应用

本文分析了常规车身ＣＡＤ／ＣＡＭ技术所存在的弊病，提出了采用并行工程的原理进行车身设计，工装设计与制造的方法，重点论述了实施车身并行工程的一些要点，如建立集成化的产品数据模型，实施ＣＡＤ／ＣＡＰＰ／ＣＡＭ集成技术及建立多功能小组等。     

震后交通需求预测的修正四阶段法

将城市震后交通系统运行划分为两个阶段:震后应急阶段及震后恢复阶段,并根据地震环境下不同恢复阶段的社会经济活动及交通系统特性对传统交通预测四阶段法———出行产生、出行分布、方式划分、交通分配的宏观模型进行修正,讨论不同模型参数的变化趋势,建议参数的调整原则及方法,进而以修正四阶段法为基础进行震后交通需求预测。该方法简便易行,预测结果可对城市交通系统防灾规划提供决策依据。     

The perspectives of research for enhancing active safety based on advanced control technology

This paper considers the scope and the methodologies for enhancing active safety of road vehicles by sensing and control technologies. The first part of this paper introduces statistical data of traffic accidents in Japan, and describes the development of the drive recorder for accident/incident survey and analysis. Based on vehicle dynamics data, the algorithm of the drive recorder for capturing near-miss incident data is introduced. The second part of this paper reviews control problems of vehicle dynamics on micro-scale electric vehicles for enhancing vehicle dynamics and driving assistance function. In particular, the direct yaw moment control using in-wheel-motors and the active front steering control algorithm are described. The third part of the paper introduces the advanced driver assistance system adapted to driver characteristics and traffic situations. This part mainly describes an adaptive system, which adjusts the assisting manoeuvre depending on individual driver behaviour and situation, and some experimental investigations using the active interface vehicle and driving simulator. Finally, some perspectives and new challenges for future research on vehicle control technology are mentioned.     

Heavy-duty vehicle modelling and longitudinal control

This paper addresses modelling, longitudinal control design and implementation for heavy-duty vehicles (HDVs). The challenging problems here are: (a) an HDV is mass dominant with low power to mass ratio; (b) They possess large actuator delay and actuator saturation. To reduce model mismatch, it is necessary to obtain a nonlinear model which is as simple as the control design method can handle and as complicated as necessary to capture the intrinsic vehicle dynamics. A second order nonlinear vehicle body dynamical model is adopted, which is feedback linearizable. Beside the vehicle dynamics, other main dynamical components along the power-train and drive-train are also modelled, which include turbocharged diesel engine, torque converter, transmission, transmission retarder, pneumatic brake and tyre. The braking system is the most challenging part for control design, which contains three parts: Jake (engine compression) brake, air brake and transmission retarder. The modelling for each is provided. The use of engine braking effect is new complementary to Jake (compression) brake for longitudinal control, which is united with Jake brake in modelling. The control structure can be divided into upper level and lower level. Upper level control uses sliding mode control to generate the desired torque from the desired vehicle acceleration. Lower level control is divided into two branches: (a) engine control: from positive desired torque to desired fuel rate (engine control) using a static engine mapping which basically captures the intrinsic dynamic performance of the turbo-charged diesel engine; (b) brake control: from desired negative torque to generate Jake brake cylinder number to be activated and ON/OFF time periods, applied pneumatic brake pressure and applied voltage of transmission retarder. Test results are also reported.     

A comparative study of equivalent modelling for multi-axle vehicle

In this paper, equivalent modelling methods of a multi-axle vehicle are presented and compared. Firstly, for the sake of comparison, a single-track model of a three-axle and a two-axle vehicle is developed, and then existing equivalent modelling derivations are presented and discussed. Next, the proposed model-based dynamic equivalence of force/moment at the centre of gravity (CG) is introduced and optimised. It represents the approximately equivalent steady-state and transient response of the yaw rate and side slip angle, which allows different cornering stiffness on the central and rear axle. Finally, to demonstrate how the proposed method is advantageous to the other equivalent models available in the literature, different simulation cases are compared in the dimension of time-domain, eigenvalues characteristics and frequency-domain. Furthermore, the proposed method is extended to any multi-axle vehicle configurations and a general expression is formulated.     

如何建立多商业中心模式解决城市交通问题

文章对城市交通拥堵及其解决措施进行了探讨,为优化单商业中心城市交通资源使用,缓解城市交通拥堵,提出建立多个次级商业中心的设想和实现方式。并建立简单模型对单商业中心模式与多商业中心模式进行比较分析,证明从解决交通问题的角度考虑,城市采取多商业中心模式优于单商业中心模式。     

微观仿真模型的建立及数据分析

在评价由道路系统以及交通量的改变而引起的交通行为特征变化时,交通微观仿真模型正迅速地成为首选的工具。交通微观仿真模型与传统分配模型在建立、产生结果和报告等方面存在某些共性,但也有很多不同之处。从对数据要求的讨论到模型的建立,介绍了应用微观仿真模型的全过程,并探讨了如何使用微观仿真模型对不同设计方案进行评价,进而分析各方案所产生的效果。