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1.
Exhaust emissions and fuel consumption of Heavy Duty Vehicles (HDVs) in urban and port areas were evaluated through a dedicated investigation. The HDV fleet composition and traffic driving from highways to the maritime port of Genoa and crossing the city were analysed. Typical urban trips linking highway exits to port gates and HDV mission profiles within the port area were defined. A validation was performed through on-board instrumentation to record HDV instantaneous speeds in urban and port zones. A statistical procedure enabled the building-up of representative speed patterns. High contrasts and specific driving conditions were observed in the port area. Representative speed profiles were then used to simulate fuel consumption and emissions for HDVs, using the Passenger car and Heavy duty Emission Model (PHEM). Complementary estimations were derived from Copert and HBEFA methodologies, allowing the comparison of different calculation approaches and scales. Finally, PHEM was implemented to assess the performances of EGR or SCR systems for NOX reduction in urban driving and at very low speeds.The method and results of the investigation are presented. Fuel consumption and pollutant emission estimation through different methodologies are discussed, as well as the necessity of characterizing very local driving conditions for appropriate assessment. 相似文献
2.
现阶段我国科学技术发展水平的提升,对社会的不断进步及生产力的提高提供了重要的技术支持.实践中为了更好地应对新时期的形势变化,加强电气工程建设,促进电工电子发展,则需要考虑这些方面的技术应用,落实好具体的研究工作,确保电气工程及电工电子应用、发展状况良好性,更好地体现出技术合理选用的重要性,满足相关生产活动高效开展要求,... 相似文献
3.
Over the past decade, activity scheduling processes have gained increasing attention in the field of transportation research. However, still little is known about the scheduling of social activities even though these activities account for a large and growing portion of trips. This paper contributes to this knowledge. We analyze how the duration of social activities is influenced by social activity characteristics and characteristics of the relationship between the respondent and the contacted person(s). To that end, a latent class accelerated hazard model is estimated, based on social interaction diary data that was collected in the Netherlands in 2008. Chi-square tests and analyses of variance are used to test for significant relations between the latent classes and personal and household characteristics. Findings suggest that the social activity characteristics and the characteristics of the relationship between the socializing persons are highly significant in explaining social activity duration. This shows that social activities should not be considered as a homogenous set of activities and it underlines the importance of including the social context in travel-behavior models. Moreover, the results indicate that there is a substantial amount of latent heterogeneity across the population. Four latent classes are identified, showing different social activity durations, and different effects for both categories of explanatory variables. Latent class membership can be explained by household composition, socio-economic status (education, income and work hours), car ownership and the number of interactions in 2 days. 相似文献
4.
回顾了人的可靠性分析发展的历史和现状,重点对现在已存在的人的可靠性分析方法进行了介绍分析,提出并简要介绍了两种在军事活动中适用的人的可靠性评估方法的基本原理:基于粗糙集的人的可靠性评估法和基于贝叶斯的人的可靠性评估法,最后分析了人的可靠性研究中存在的问题。 相似文献
5.
雷云 《武汉船舶职业技术学院学报》2012,11(3):149-151
随着教学改革的不断深入,英语教师越来越重视活动在课堂中的运用。本文首先分析了大学英语课堂活动中存在的问题,再从五个方面提出了策划课堂活动时提高活动有效性的原则及改进方法,这五个方面分别是:明确活动的目标性、加强活动实用性、确保活动的可行性、把握活动的可控性、提高活动的参与性。 相似文献
6.
This paper presents a multiple discrete-continuous econometric structure to model the daily time-investment decisions of couples
in solo- and joint-discretionary activities incorporating intra-personal and inter-personal inter-dependencies. The empirical
model was estimated using data from the 2000 Bay Area Travel Survey. The results indicate evidence of the positive impact
of vehicle availability on independent activity participation and the negative impacts of the presence of children and mandatory
time investments on the joint discretionary-activity engagement of the spouses. In addition, we also find the mandatory- and
maintenance-activity-participation characteristics of the spouse to influence the discretionary activity choices of individuals.
Finally, the analysis also indicates a strong impact of common unobserved factors on the decisions of couples. From a policy
analysis perspective, these results imply that demand-management actions directly impacting one adult could also result in
changes to the activity patterns of his/her spouse and to changes in joint activity participation characteristics.
Dr. Sivaramakrishnan Srinivasan is an Assistant Professor in the Department of Civil and Coastal Engineering at the University of Florida. His research interests
include travel-behavior analysis, activity-based travel-demand modeling, and the application of advanced econometric methods
for transportation problems.
Dr. Chandra R. Bhat has contributed toward the development of advanced econometric techniques for travel behavior analysis, in recognition of
which he received the 2004 Walter L. Huber Award and the 2005 James Laurie Prize from the American Society of Civil Engineers
(ASCE). 相似文献
7.
文章论述了海事行政执法自由裁量权的定义、种类和目前行使海事行政执法自由裁量权存在的问题及造成这种问题的原因,提出了正确行使规范海事行政执法自由裁量权的建议。 相似文献
8.
叶琳琳 《广东交通职业技术学院学报》2008,7(4):87-89
质的研究方法是一种通过在自然情境下的双向互动,对研究现象进行整体性探究、继而形成解释性理解的方法。在高职院校,基层教学单位借助该种方法开展教研活动,能够提升教学实践的效果,有助于锻炼教师的教研能力、推进院本教研模式的创新。 相似文献
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10.
Xin ZHAO Hongzhi GUAN Liyuan GONG 《Journal of Transportation Systems Engineering and Information Technology》2011,11(4):85-90
Previous researches in activities-decision have more in-depth study in context of individuals, while less work has been done within household activity decisions. The structural equation model is applied to analyze the relationship of three household activity categories on holiday using data from 2009 Jinan travel survey. Six attributes were first chosen as exogenous variables for the structural equation model. Meanwhile, six activity characteristic indexes were selected as endogenous variables including activity duration time and activity times in three kinds of activity, hereby Subsistence activity, maintenance activity and discretionary activity. respectively. Then, the paper attempted to discuss the correlation of all types of activities behavior through analyzing not only the influence of household economics and family members factors on activity but the correlation of holiday activities. The research shows that complex relationships among composition of the family, economic status, and activities-decision can be captured by the structural equation model structure. Specifically, the results show that flexibility of three categories activities will affect the activities of decision-making. 相似文献