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81.
Battery Electric vehicles (BEVs) are generally considered as potentially contributing to the reduction of CO2 emissions. Consequently, many countries have promoted (or are in the process of promoting) policies aimed at directly or indirectly subsidizing BEVs to accelerate their market uptake. The aim of this paper is to assess whether BEVs’ subsidies are justified (and by what amount) with reference to the carbon component, distinguishing by car segments and countries. To address these research questions, a simulation model is developed, based on the most recent and reliable data available. The model estimates and monetizes the Well-to-Wheel CO2 emissions of six car segments in 28 European countries. The monetary value of the difference of the CO2 emissions between the non-BEVs and the BEVs ranges from −€1133 (tax) to +€3192 (subsidy), depending on the car segment and on the nation considered. These results are then compared to the policies about alternative fuels adopted by the single EU countries, suggesting in some cases the necessity to rethink such incentives.  相似文献   
82.
Level 3 of the ERTMS/ETCS improves the capacity of railways by replacing fixed-block signalling, which prevents a train to enter a block occupied by another train, with moving block signalling, which allows a train to proceed as long as it receives radio messages ensuring that the track ahead is clear of other trains. If messages are lost, a train must stop for safety reasons within a given deadline, even though the track ahead is clear, making the availability of the communication link crucial for successful operation.We combine analytic evaluation of failures due to burst noise and connection losses with numerical solution of a non-Markovian model representing also failures due to handovers between radio stations. In so doing, we show that handovers experienced by a pair of chasing trains periodically affect the availability of the radio link, making behavior of the overall communication system recurrent over the hyper-period of periodic message releases and periodic arrivals at cell borders. As a notable aspect, non-Markovian transient analysis within two hyper-periods is sufficient to derive an upper bound on the first-passage time distribution to an emergency brake, permitting to achieve a trade-off between railway throughput and stop probability. A sensitivity analysis is performed with respect to train speed and headway distance, permitting to gain insight into the consequences of system-level design choices.  相似文献   
83.
    
Using a primary dataset from an experimental survey in eight European cities, this study identified the key determinants of satisfaction with individual trip stages as well as overall journey experience for different travel modes and traveler groups. Multivariate statistical analyses were used to examine the relationships between overall satisfaction and travel experience variables, trip complexity, subjective well-being indices, travel-related attitudes as well as individual- and trip-specific attributes. The results indicate that for certain traveler groups, such as women, young and low-income or unemployed travelers, there are distinctive determinants of satisfaction with trip stages for various travel modes. The results also indicate that satisfaction with the primary trip stage is strongly linked to overall trip satisfaction, while satisfaction levels with access and egress trip stages are strongly related to satisfaction with the primary trip stage. Past experience, traveler expectations and attitudes, and the emotional state of travelers are also significant explanatory variables for travel satisfaction. The results indicate that when an individual consciously chooses a particular travel mode, they will report a higher level of satisfaction with that chosen mode. Notwithstanding, while past experience highly influences an individual’s current travel satisfaction, the more they travel with the current mode, the less satisfied they are with their choice. The results of this study highlight the importance of gaining a better understanding of the interaction between instrumental variables and non-instrumental variables at different trip stages and the influence on user preferences, satisfaction and decision-making processes.  相似文献   
84.
行人安全技术应用在汽车上可以降低汽车一行人碰撞中行人的伤害,因此,我国应该实施行人保护法规,促使汽车生产企业加速行人保护方面的研究。文章通过对道路交通事故中行人伤害所占的比例分析,说明了在我国开展行人保护研究的重要意义。阐述了在汽车与行人的碰撞过程中,汽车可能对行人造成伤害的主要部分,从而对改进汽车相关结构提出重要依据。力图从根本上提高汽车的被动安全性能,使我国的汽车工业向更加完善的方向发展,从而使我国的汽车技术和世界汽车技术接轨。  相似文献   
85.
全球卫星导航系统的构成及其比较   总被引:4,自引:0,他引:4  
介绍了全球卫星定位系统、格洛纳斯卫星定位系统、伽利略卫星定位系统和北斗卫星定位系统的构成、优势等基础上,论述了各系统在技术上的比较。  相似文献   
86.
美国与欧盟的交通政策对比分析   总被引:1,自引:1,他引:0  
结合美国与欧盟交通政策的制定背景,分别针对交通政策的目标、重点和内容,对美国与欧盟的交通政策进行比较,发现二者的政策在凸显自身特点的同时,在以人为本、可持续发展、全球化运输等方面又均体现出共性,符合交通运输发展的要求.其对我国交通政策的制定具有一定的借鉴意义。  相似文献   
87.
This paper considered the problem of hedging a European call (put) option for a diffusion model where the asset price is influenced by n uncertain factors. The market is thus incomplete implying that perfect hedging is not possible. To derive a hedging strategy, it follows the approach based on the idea of hedging under a mean-vari-ance criterion suggested by Schweizer. A very simple solution of this hedging problem by using the numeraire method was presented and some examples with explicit solutions were given.  相似文献   
88.
欧盟可持续交通系统研究综述   总被引:1,自引:0,他引:1  
对过去15年欧盟进行的交通系统可持续性研究进行了回顾,明确了不足之处并详细阐述了未来的发展方向。介绍了可持续发展和可持续交通系统的概念,指出研究重点要实现影响因素指标的量化,使可持续交通系统评估具有可操作性。探讨了评估可持续交通系统的绝对尺度和相对尺度,利用实例对二者的评估作用进行了对比。通过回顾欧盟在可持续交通方面进行的第4次、第5次和第6次框架计划研究,指出未来的研究方向是以绩效指标为基础,改进现有评估系统或发展创新性的评估系统,以检测欧盟交通系统的可持续性。  相似文献   
89.
作为一个特殊的国际组织,欧洲联盟的性质问题一直被广泛讨论。随着欧盟一体化程度的不断加深以及欧盟宪法条约草案的出台,欧盟究竟是一个什么样的组织就更值得研究了。文章通过对欧盟宪法条约草案内容的分析,认为欧洲联盟是一个联邦与邦联的混合体,但更倾向于向联邦发展。  相似文献   
90.
在中国古代,天文学一直是由皇家垄断的。这种垄断局面直到明代后期才开始被打破,而进入清代之后,随着西方天文学在清代取得官方地位,局面发生了剧烈的、彻底的改变。这一改变对清代中国的政治、哲学、科学、文化等方面的影响,值得深入探讨。清代在最重要的政治象征———历法和皇家天学———上改用欧洲天文学,为此还发生了激烈的争论。天文学又成为清代上层社会的一种时髦,民间的天文学研究也受到官方鼓励。中国一度非常接近欧洲的天文学前沿,但中国天文学最终未能继续前进,则主要是内部的原因。  相似文献   
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