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The objective of the present study is the assessment of the environmental impact of a bivalent (bi-fuel) vehicle, running either on gasoline or compressed natural gas (CNG). To that aim, a Euro 6 passenger car was tested under various real-world driving conditions. In order to cover the full range of conventional powertrains currently in the market, the tests were also repeated on a Euro 6 diesel passenger car. Both cars were driven in two routes, the first complying with the regulation limits and the second going beyond them. Carbon monoxide (CO), nitrogen oxides (NOx) and particle number (PN) emissions were recorded using a Portable Emissions Measurement System (PEMS). Apart from the aggregated emission levels, in g/km, the exact emission location along the route was also assessed. Natural gas proved beneficial for CO and PN emissions, the level of which always remained below the respective legislation limits. On the other hand, under the dynamic driving conditions with gasoline, the relevant limits were exceeded. Cold start, occurring at the beginning of the urban part, and motorway driving were identified as major contributors to total emissions, especially in gasoline mode. However, the application of natural gas was associated with a penalty in NOx emissions, which were significantly increased as compared to gasoline. Local peaks within the urban part were identified in CNG mode. In any case, the diesel vehicle was by far the highest NOx emitter. 相似文献
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The effect of corruption on airport productive efficiency is analyzed using an unbalanced panel data of major European airports from 2003 to 2009. We first compute the residual (or net) variable factor productivity using the multilateral index number method and then apply robust cluster random effects model in order to evaluate the importance of corruption. We find strong evidence that corruption has negative impacts on airport operating efficiency; and the effects depend on the ownership form of the airport. The results suggest that airports under mixed public–private ownership with private majority achieve lower levels of efficiency when located in more corrupt countries. They even operate less efficiently than fully and/or majority government owned airports in high corruption environment. We control for economic regulation, competition level and other airports’ characteristics. Our empirical results survive several robustness checks including different control variables, three alternative corruption measures: International Country Risk Guide (ICRG) corruption index, Corruption Perception Index (CPI) and Control of Corruption Index (CCI). The empirical findings have important policy implications for management and ownership structuring of airports operating in countries that suffer from higher levels of corruption. 相似文献
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欧洲港口海运产业集群发展模式 总被引:1,自引:0,他引:1
欧洲有着众多的港口海运业集群,典型的有以伦敦为核心的英国海运服务业集群、以鹿特丹和阿姆斯特丹为中心的荷兰港口与港口服务业集群和以奥斯陆为中心的挪威航运与航运技术集群.梳理发现,港口海运业集群发展的基本模式为:航运和港口资源的历史累积体现了路径依赖,国家政策革新和企业创新是外部动力,解除路径锁定及生产服务于全球航运市场的垄断性产品或规则是核心动力.港航企业集群发展的关键路径是营造发展环境和蓄积专业性知识,完善专项资源配置能力和功能,通过企业成群、产业成链、市场创新,形成多部门、多层次、协调合作、共同提升的国际港口和航运服务体系,提供迅捷而专业的解决方案,引领国际港航服务发展.中国沿海港口产业和港口城市迅猛发展,应科学认识港航集群,多方联动研发创新,促进中国港口海运集群发展. 相似文献
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葛晓红 《兰州交通大学学报》2013,(4)
锚杆是一种常见的边坡防护形式,要使锚杆发挥良好作用,工程安全经济,就需要对锚杆进行拉拔试验。阿尔及利亚东西高速公路 M5标段为了确定不同地层下锚杆的极限抗拔拉力、极限位移,按照欧洲标准进行了大量拉拔试验,试验所使用的仪器设备、采用的试验参数、执行的试验步骤及采取的数据处理方法均按照欧洲标准规定的方法进行。 相似文献
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为减小列车由直线进入曲线时车轮对轨道产生的横向冲击力,对曲线入口的结构性晃车问题进行了分析,进而对轮轨游间及相关技术标准进行了讨论,从机车车辆和线路2个方面提出了建议。 相似文献
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文章从设计标准、交通荷载、材料参数及设计方法四方面阐述我国现行规范中沥青路面结构设计的原理及存在的问题,并提出了需进一步完善的建议。 相似文献
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反复弯曲试验是考核电缆类或裸导线机械性能的一个重要指标,但各国对反复弯曲试验做法和理解不尽相同,接触网导线作为一种特殊的裸导线有其自身的特点和要求,结合国际标准,提出对接触网导线反复弯曲试验的一些看法。 相似文献
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欧盟铁路改革的方向与进程 总被引:3,自引:0,他引:3
铁路运输是欧共体/欧盟共同运输政策推行中遇到困难较多的行业,其一体化进程曾远远落后于其他运输方式,然而从20世纪90年代初开始,铁路在共同运输政策中的地位却日益受到重视。文章根据对欧盟有关机构出台相关政策文件的分析,解释了发生这一转变的原因并把欧盟铁路改革的过程分为3个阶段进行介绍与评价:以91/440指令系列为标志的起步阶段;以1996年欧盟委员会"复兴共同体铁路战略"白皮书为起点,第一个铁路改革一揽子方案为中心的改革深化阶段;和以2001年欧盟委员会白皮书"已到决定性时刻"为起点,第二个铁路改革一揽子方案为中心的最新进展阶段。 相似文献
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近年来,我国的企业在"一带一路"沿线国家承揽了较多水运工程桩基项目,但因对国外规范了解不够深入,给桩基完整性试验检测的开展带来很大困扰。以中国《水运工程地基基础试验检测技术规程》和美国ASTM(D5882、D4945、D6760、D7949)、欧洲标准(EN1997、EN1536、EN12699)为例,详细比较中国、美国、欧洲3套现行规范在水运工程桩基完整性试验检测中部分条款之差异,主要结果有:1)中国规范规定了完整性试验检测的比例并将桩的完整性分为4类。2)美国规范包括了热异常法,丰富了检测方法。3)美国规范只规定了如何进行试验,一般不规定如何使用试验结果。4)欧洲规范仅提及了完整性检测可采用的方法,并未进行具体规定,一般均按所在地国家标准进行。 相似文献