Farm tractor models for research and development purposes

The modelling problems related to the simulation of the dynamics of farm tractors are dealt with. The aim is to develop reliable mathematical models to speed-up the research and development activities in which farm tractors and their sub-systems (driveline, steering and suspension system, etc.) are to be conceived and designed. Two models of farm tractors have been developed. The first model is based on a proprietary software, able to quickly simulate the motion of a vehicle on smooth or rough soil. The second model has been developed by the commercial software ADAMS/Car^®, which allows to model complicated transmission and suspension systems. In both of the two models, the tyres, the transmission system, the suspension system, the steering system, the engine and the body inertia are carefully described mathematically. Both of the two models are defined in a parametric way. Particular attention has been devoted to the measurements of the tyre characteristic and of the inertia parameters of the farm tractor body. For the measurement of tyre characteristics, a new instrumented wheel hub has been used. The accurate measurement of both the tyre characteristic and body inertia tensor has allowed a good agreement between measured and computed time histories referring to a number of validation manoeuvres performed either on-road or off-road. The derived farm tractor models could simulate the working conditions of a generic farm tractor while hauling a plough or while running at a relatively high speed on a rough soil or while steering on a sloped, soft surface.     

Urban Traffic Flow Prediction Using a Spatio-Temporal Random Effects Model

Traffic prediction is critical for the success of intelligent transportation systems (ITS). However, most spatio-temporal models suffer from high mathematical complexity and low tune-up flexibility. This article presents a novel spatio-temporal random effects (STRE) model that has a reduced computational complexity due to mathematical dimension reduction, with additional tune-up flexibility provided by a basis function capable of taking traffic patterns into account. Bellevue, WA, was selected as the model test site due to its widespread deployment of loop detectors. Data collected during the 2 weeks of July 2007 from 105 detectors in the downtown area were used in the modeling process and traffic volumes predicted for 14 detectors for the entire month of July 2008. The results show that the STRE model not only effectively predicts traffic volume but also outperforms three well-established volume prediction models, the enhanced versions of autoregressive moving average (ARMA) and spatiotemporal ARMA, and artificial neural network. Even without further model tuning, all the experimental links produced mean absolute percentage errors between 8% and 16% except for three atypical locations. Based on lessons learned, recommendations are provided for future applications and tune-up of the proposed STRE model.     

浮式防波堤的拖航阻力试验研究

本文对一种圆筒型的浮式防波堤进行了详细的介绍,在此基础上对拖航过程进行了概述。对于本次试验的试验概况以及工况进行了设定,根据要求对试验设备进行了安装和标定。通过模型试验的方法对圆筒型浮式防波堤的拖航过程中的拖航阻力进行了较为透彻的研究,分别分析了两种工况下圆筒型浮式防波堤随着航速增加拖航阻力的变化情况。通过比较可以得出两种工况下浮式防波堤拖航阻力的差距,为浮式防波堤实际的拖航工程提供更为可靠的依据,以此来保证拖航过程的经济、安全。     

TJ165架桥机装载加固方案的研制和试验

从主机及机动平车、倒装龙门架、机臂4个方面介绍TJ165架桥机的装载加固方案,并进行装载加固方案的计算及验算。     

新能源汽车动力总成测试系统平台

以荣威550PHEV插电式混合动力轿车为例,根据混合动力汽车动力系统的特性和不同测试阶段要求,设计开发了具备不同功能的测试平台。介绍了荣威550PHEV的动力总成架构和主要测试阶段,以及各阶段测试系统平台的功能要求、架构方案、特殊测试设备、通讯接口及注意事项等。     

液压混合动力公交车制动性能仿真与试验分析

针对城市公交车运行特点和在城市运行工况下燃油经济性差的问题,提出一种新型液压混合动力系统,并建立制动回收过程动力学模型、能量再生过程动力学模型和柴油机液压起动模型等,对其制动性能进行仿真,最后进行了样机台架、实车道路试验。试验结果表明,该液压混合动力公交车可实现汽车制动能量回收等功能,在典型城市循环工况下制动能量回收率为69.7%,制动能量再生率为32.8%,液压起动发动机时间为1.7 s。     

50%假人胸部刚度稳定性研究

针对不同坐姿及不同撞击点下50%假人胸部刚度稳定性进行了摆锤撞击试验。结果表明,50%假人胸部刚度在相同作用力撞击下具有较好的稳定性,不会因姿态轻微改变及受力位置差异而发生明显变化,但撞击速度越高则刚度越小,且碰撞点侧移则刚度增大。运用假人胸部刚度稳定特性对碰撞试验结果分析能起到较好的支持作用,可指导整车碰撞试验中前排安全气囊的设计优化。     

压燃式发动机汽车自由加速法排气烟度（滤纸烟度）检验作业指导书

自由加速排气烟度滤纸烟度法是检验压燃式发动机汽车排气污染物常用方法之一。本指导书详细阐述了滤纸式烟度计日常检查方法、自由加速滤纸烟度法检验步骤以及滤纸式烟度计校准方法,并提出使用维护方法,具有指导意义。     

微型汽车传动系统效率试验台的研制

针对某微型汽车传动系统效率偏低的问题,研制开发了一种用于测试微型汽车传动系统效率的试验台。选用直流回馈式试验台,以电动机为动力源,采用电力测功机直接转矩控制变频调速系统,软件系统采用VC＋＋作为开发工具,模块化设计。利用该试验台可以对微型汽车整车传动系统或者其部件进行效率测试,为该传动系统的优化设计提供了方向和依据。     

重型卡车总线检测技术研究

本文对比分析了几种测试仪器设备的测试效果、适用性、经济型和兼容性,讨论了适合重型汽车总线网络的测试手段。