Quasi steady-state aerodynamic model development for race vehicle simulations

Presented in this paper is a procedure to develop a high fidelity quasi steady-state aerodynamic model for use in race car vehicle dynamic simulations. Developed to fit quasi steady-state wind tunnel data, the aerodynamic model is regressed against three independent variables: front ground clearance, rear ride height, and yaw angle. An initial dual range model is presented and then further refined to reduce the model complexity while maintaining a high level of predictive accuracy. The model complexity reduction decreases the required amount of wind tunnel data thereby reducing wind tunnel testing time and cost. The quasi steady-state aerodynamic model for the pitch moment degree of freedom is systematically developed in this paper. This same procedure can be extended to the other five aerodynamic degrees of freedom to develop a complete six degree of freedom quasi steady-state aerodynamic model for any vehicle.     

Design and validation of a slender guideway for Maglev vehicle by simulation and experiment

Normally, Maglev (magnetic levitation) vehicles run on elevated guideways. The elevated guideway must satisfy various load conditions of the vehicle, and has to be designed to ensure ride quality, while ensuring that the levitation stability of the vehicle is not affected by the deflection of the guideway. However, because the elevated guideways of Maglev vehicles in South Korea and other countries fabricated so far have been based on over-conservative design criteria, the size of the structures has increased. Further, from the cost perspective, they are unfavourable when compared with other light rail transits such as monorail, rubber wheel, and steel wheel automatic guided transit. Therefore, a slender guideway that does have an adverse effect on the levitation stability of the vehicle is required through optimisation of design criteria. In this study, to predict the effect of various design parameters of the guideway on the dynamic behaviour of the vehicle, simulations were carried out using a dynamics model similar to the actual vehicle and guideway, and a limiting value of deflection ratio of the slender guideway to ensure levitation control is proposed. A guideway that meets the requirement as per the proposed limit for deflection ratio was designed and fabricated, and through a driving test of the vehicle, the validity of the slender guideway was verified. From the results, it was confirmed that although some increase in airgap and cabin acceleration was observed with the proposed slender guideway when compared with the conventional guideway, there was no notable adverse effect on the levitation stability and ride quality of the vehicle. Therefore, it can be inferred that the results of this study will become the basis for establishing design criteria for slender guideways of Maglev vehicles in future.     

A new shared control for lane keeping and road departure prevention

In recent years, the driver's active assistances have become important features in commercialised vehicles. In this paper, we present one of these features which consists of an advanced driver assistance system for lane keeping. A thorough analysis of its performance and stability with respect to variations in driver behaviour will be given. Firstly, the lateral control model based on visual preview is established and the kinematics model based on visual preview, including speed and other factors, is used to calculate the lateral error and direction error. Secondly, and according to the characteristics of the lateral control, an efficient strategy of intelligent electric vehicle lateral mode is proposed. The integration of the vehicle current lateral error and direction error is chosen as the parameter of the sliding mode switching function to design the sliding surface. The control variables are adjusted according to the fuzzy control rules to ensure that they meet the existence and reaching condition. A new fuzzy logic-based switching strategy with an efficient control law is also proposed to ensure a level of continuous and variable sharing according to the state of the driver and the vehicle positioning on the roadway. The proposed control law acts either at the centre of the lane, as a lane keeping assistance system to reduce the driver's workload for long trips, or as a lane departure avoidance system that intervenes for unintended lane departures. Simulation results are included in this paper to explain this concept.     

运用弹性系数法预测北京机动车保有量

综述了机动车保有量的预测方法,包括时间序列回归法、神经网络法、弹性系数法等,分析了不同方法的特点,给出了相关启示。结合北京经济发展趋势,运用弹性系数法对机动车保有量进行了预测。     

浅析电动汽车中的再生制动

电动汽车可以实现再生制动。本文对变频器再生制动的原理、应用进行详细的阐述,并通过仿真加以证明。     

冷补材料在内蒙古道路养护工程中的应用

沥青路面冷补材料与技术的应用对于解决不良环境条件下的路面修补具有极大的现实意义。针对在沥青路面养护工程当中的应用推广实例,介绍了冷补材料的配制、技术要求、生产工艺以及经济效益分析。     

农村公路养护与管理的现状分析及对策研究

针对内蒙古自治区农村公路发展现状,分析了目前农村牧区公路在养护与管理方面存在的问题,并对如何完善农村牧区公路管理与养护机制提出了建设性的意见。     

缓速器的分类及其在商用汽车上的应用

探讨缓速器在商用汽车上应用的必要性以及目前使用的各种缓速器的分类及其特点。     

车辆运动方程定位原理的研究及其应用

利用车辆运动方程获取车辆行驶距离,车辆当前位置点处的道路方向作为方向角,根据航位推算原理实时推算车辆位置。通过实地跑车试验分别分析了该定位技术在车载导航系统和监控中心的应用。试验结果显示,在车辆导航系统中该技术能实现GPS盲区内的车辆连续定位功能;在监控中心中,该技术从理论上可以大大减少单个车辆和监控中心之间的信息流量,其实际应用还有待智能交通系统的进一步完善。