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811.
Philippe Lepert Franois Brillet 《Transportation Research Part D: Transport and Environment》2009,14(8):576-584
Road characteristics influence the amount of pollution generated by traffic. They govern the rolling resistance, which includes: the viscoelastic behaviour of the pavement structure, surface texture, and profile unevenness. Road works are performed on a periodic basis to maintain these characteristics at proper levels of service (e.g. safety, comfort, and noise). While such works produce additional pollution (due to congestion around worksites or extra fuel consumption along the detour route), they still result in less pollution over the long term. This article assesses the balance between an increase in gas emissions during road works and the reduction in emissions from traffic once the works are completed. It is demonstrated that when road works are introduced to correct longitudinal profiles, rather than texture, the emissions benefit is substantial. 相似文献
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《运输规划与技术》2012,35(8):825-847
ABSTRACTIn recent years, public transport has been developing rapidly and producing large amounts of traffic data. Emerging big data-mining techniques enable the application of these data in a variety of ways. This study uses bus intelligent card (IC card) data and global positioning system (GPS) data to estimate passenger boarding and alighting stations. First, an estimation model for boarding stations is introduced to determine passenger boarding stations. Then, the authors propose an innovative uplink and downlink information identification model (UDI) to generate information for estimating alighting stations. Subsequently, the estimation model for the alighting stations is introduced. In addition, a transfer station identification model is also developed to determine transfer stations. These models are applied to Yinchuan, China to analyze passenger flow characteristics and bus operations. The authors obtain passenger flows based on stations (stops), bus lines, and traffic analysis zones (TAZ) during weekdays and weekends. Moreover, average bus operational speeds are obtained. These findings can be used in bus network planning and optimization as well as bus operation scheduling. 相似文献
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Paulus Teguh Aditjandra Xinyu CaoCorinne Mulley 《Transportation Research Part A: Policy and Practice》2012,46(1):22-32
The objective of this study is to explore whether changes in neighbourhood characteristics bring about changes in travel choice. Residential self-selection is a concern in the connections between land-use and travel behaviour. The recent literature suggests that a longitudinal structural equations modelling (SEM) approach can be a powerful tool to assess the importance of neighbourhood characteristics on travel behaviour as opposed to the attitude-induced residential self-selection. However, the evidence to date is limited to particular geographical areas and evidence from one country might not be transferrable to another because of differences in land-use patterns and land-use policies. The paper is to address the gap by extending the evidence using British data. The case study is based on the metropolitan area of Tyne and Wear, North East of England, UK. A SEM is applied to 219 respondents who reported residential relocation. The results identify that neighbourhood characteristics do influence travel behaviour after controlling for self-selection. For instance, the more people are exposed to public transport access, the more likely they drive less. Neighbourhood characteristics also impact through their influence on car ownership. A social environment with vitality also reduces the amount of private car travel. These findings suggest that land-use policies at neighbourhood level can play an important role in reducing driving. 相似文献
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大跨径钢桁架拱桥的简单动力特性分析 总被引:1,自引:1,他引:1
自振特性是反映桥梁动力特性的主要模态参数,它包括自振频率、振型反映了桥梁的刚度指标,是评价桥梁动力性能的主要依据。采用SAP2000程序,建立了大宁河钢桁架拱桥的三维空间有限元模型,对全桥开展了动力特性分析。分析结果为该类型结构桥提供参考。 相似文献
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针对减摇陀螺装置内部的热特性问题,考虑陀螺内部真空状态的影响和环槽齿片式散热器的散热作用,基于内部稀薄空气状态的雷诺应力模型,根据具体工况条件建立整个陀螺系统的热态特性分析模型,进而研究陀螺内部的温度场和热通量等热状态性能。结果表明:在一定的真空气压和环槽齿片式散热器的几何条件下,散热器内部的稀薄空气适用于连续性假设,利于热量的散发;装置内部支承轴承高速生热以及内装驱动电机发热的叠加效应使得靠近电机部位的下轴承温度较高,需要改进下端散热器的几何参数等,以加强散热效果、改善工况条件。 相似文献
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为研究舱壁布置形式对圆柱壳结构声学性能的影规律,文章应用有限元方法对等间距与不等间距分舱圆柱壳模型的振动响应进行了计算,以此为输入可计算获得壳体的均方法向速度级声学传递函数,并在典型频率处应用波数谱分析方法将壳体空间域振动场转换到波数域上,对壳体的振动进行波形分离与量化,分析获得了舱壁等间距布置与不等间距布置圆柱壳在典型激励下的结构声学性能,并解释其机理.研究表明:对垂向激励,圆柱壳不等间距分舱相比等间距分舱具有较好的结构声学性能,但对轴向激励,两者区别不明显.若将不等间距分舱与局部结构补强措施相结合,则可使得圆柱壳在两典型工况下均能获得更优的结构声学性能. 相似文献