Active travel as a pro-environmental behaviour: An integrated framework

A travel mode may be chosen due to its emotional appeal (affective motive) or to express social status (symbolic motive). Previous studies have overlooked the role of such motives in active mode use as pro-environmental behaviour. This study aims to examine the role of symbolic and affective motives, together with other significant theoretical perspectives, to explain the share of active modes of transport in trips to the university. It adds to the previous literature by considering the share of active modes of transport in different seasons. We collected a total of 316 completely filled questionnaires (response rate = 75.4 percent) from a cross-sectional self-administered survey in February 2019 in Trondheim, Norway. Among the psychological variables related to active mode use, only affective motives were found significant in both summer and winter. Environmental self-identity predicted both types of motives. No evidence suggested that personal environmental norms and attitudes towards transportation significantly explained active mode share, although car-related subjective norms reached significance. Furthermore, there was no evidence that environmental attitudes towards transportation had a mediating effect between motives and active mode use. Cycling journey time between place of residence and campus was found significant in the share of active modes of transport in both seasons. The results have important ramifications for the provision of relevant regulations and raising positive support from society to enhance the share of active modes of travel to the university.     

Multi-criteria analysis of optimal signal plans using microscopic traffic models

Increasing concerns on environment and natural resources, coupled with increasing demand for transport, put lots of pressure for improved efficiency and performance on transport systems worldwide. New technology nowadays enables fast innovation in transport, but it is the policy for deployment and operation with a systems perspective that often determines success. Smart traffic management has played important roles for continuous development of traffic systems especially in urban areas. There is, however, still lack of effort in current traffic management and planning practice prioritizing policy goals in environment and energy. This paper presents an application of a model-based framework to quantify environmental impacts and fuel efficiency of road traffic, and to evaluate optimal signal plans with respect not only to traffic mobility performance but also other important measures for sustainability. Microscopic traffic simulator is integrated with micro-scale emission model for estimation of emissions and fuel consumption at high resolution. A stochastic optimization engine is implemented to facilitate optimal signal planning for different policy goals, including delay, stop-and-goes, fuel economy etc. In order to enhance the validity of the modeling framework, both traffic and emission models are fine-tuned using data collected in a Chinese city. In addition, two microscopic traffic models are applied, and lead to consistent results for signal optimization. Two control schemes, fixed time and vehicle actuated, are optimized while multiple performance indexes are analyzed and compared for corresponding objectives. Solutions, representing compromise between different policies, are also obtained in the case study by optimizing an integrated performance index.     

深圳市道路交通噪声污染现状及防治对策

文章在分析深圳市道路交通噪声污染现状的基础上,讨论了其污染成因,并提出控制与削减城市交通噪声污染的对策和建议,为有效改善城市道路交通噪声污染提供科学依据。     

基于动刚度和模态应变能的某车NVH性能改善研究

本文通过创建某车的白车身模型和带内饰车身模型,进行车身噪声传递函数分析,并结合车身的模态应变能分布情况和动刚度分析结果,查找并确定导致车内噪音较大的原因,并提出了几种优化方案,采用CAE方法选择最佳方案,经试验验证,最终改善车身的NVH性能。     

压路机实时压实信号的降噪研究

为了得到更加真实有用的压路机信号,针对振动压路机钢轮的振动加速度信号采集中所存在的噪声,在4种不同阀值原则下对振动加速度信号进行小波降噪处理,采用IIR低通滤波器对同一信号进行滤波去噪。结果表明,小波降噪方法在对压路机钢轮振动信号的处理中能够更好地降噪并保留有用信号。     

某车型风噪问题分析及改善

风噪是影响汽车高速行驶时乘坐舒适性的重要因素。本文主要阐述了利用声音听诊器、超声波泄漏检测仪和封堵排除法对某车型风噪问题的分析和改善过程。     

前副车架安装动力吸振器对加速车内噪声的改善

通过整车状态下副车架约束模态和油门全开道路行驶工况下的噪声振动测试和分析,确定了车内"嗡嗡"声的根源(发动机二阶激励引起副车架共振传递至车内)及其频段。在此基础上,采用在前副车架的悬置安装点附近安装一个动力吸振器的方案,在此之前为了确定吸振器的质量,讨论了等效质量的两种理论计算方法及阻尼比的设定,试验表明,吸振器的应用有效地衰减了副车架在该频段的振动,从而减小了对副车架垂向弯曲模态的激励,基本上消除了车内的噪声峰值,显著改善了加速工况下的车内噪声。     

“通过噪声”新法规对NVH的挑战

为解读新版《汽车加速行驶车外噪声限值及测量方法》征求意见稿提出的各项要求及方法,从试验条件、试验方法及结果处理等方面,阐述了新旧法规测试方法的差异。在按照新法规方法对某款汽车进行试验后,通过排除法对影响其通过噪声的各项因素进行了定性分析,总结出各系统影响所占的百分比。对于汽车企业未来开发车型如何满足新法规各项要求具有一定的指导意义。     

某轻型客车双质量飞轮应用

本文首先阐述了多质量飞轮产生的背景,对双质量飞轮式扭振减振器的结构和性能作了简要的说明,其在传动系共振噪声优化改善方面有着很好的作用和效果。针对某轻型客车存在传动系存在共振噪声的问题,分别对装单质量飞和双质量飞轮的噪声和振动进行对比测试,通过对比测试数据结果,共振噪声得到了很好的改善和解决。     

基于Fluent与Virtual Lab发动机风扇气动噪声的联合仿真

以某款发动机风扇为研究对象,采用数值模拟方法,应用Fluent和LMS Virtual Lab分别模拟发动机风扇流场和声场分布。将计算结果与半消音室内的风扇测试噪声进行对比,验证了联合仿真计算风扇噪声方法的准确性。在工程实际中可用于对风扇性能的初步检测,可以为下一步风扇的优化提供技术依据。