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181.
Car use per person has historically grown year-on-year in Great Britain since the 1950s, with minor exceptions during fuel crises and times of economic recession. The ‘Peak Car’ hypothesis proposes that this historical trend no longer applies. The British National Travel Survey provides evidence of such an aggregate levelling off in car mileage per person since the mid-1990s, but further analysis shows that this is the result of counter trends netting out: in particular, a reduction in per capita male driving mileage being offset by a corresponding increase in female car driving mileage. A major contributory factor to the decline in male car use has been a sharp reduction in average company car mileage per person. This paper investigates this aspect in more detail. Use of company cars fell sharply in Britain from the 1990s up to the 2008 recession. Over the same period, taxation policy towards company cars became more onerous, with increasing levels of taxation on the benefit-in-kind value of the ownership of a company car and on the provision of free fuel for private use. The paper sets out the changes in taxation policy affecting company cars in the UK, and looks at the associated reductions in company car ownership (including free fuel) and patterns of use. It goes on to look in more detail at which groups of the population have kept company cars and in which parts of the country they have been most used, and how these patterns have changed over time. A preliminary investigation is also made of possible substitution effects between company car and personal car driving and between company car use and rail travel. Clearly, the role of the company car is only one of many factors that are contributing to aggregate changes in levels of car use in Great Britain, alongside demographic changes and a wide range of policy initiatives. But, company car use cannot fall below zero, so the effect of declining year-on-year company car mileage suppressing overall car traffic levels cannot continue indefinitely. 相似文献
182.
战略机动模型是战略机动辅助决策系统的核心,是提高军队战略机动能力的重要手段。对美军主要的战略机动模型及其支撑模型进行了概述,从功能、时间约束和整体性能三个方面对美军的主要战略机动模型进行了对比分析,并探讨了对我军开展相关研究的启示。 相似文献
183.
为促进部队摩托化机动交通保障工作机制的形成和完善,提出了加强组织领导、制定出台相应法规、抓好相关计划方案配套衔接、制定安全保密规定、搞好学习培训以及明确经费来源等对策措施,以提高部队摩托化机动交通保障能力。 相似文献
184.
文章以清华大学、北京航空航天大学和东北大学等30所大学1080位信息科学与系统科学学科教师为例,基于履历信息对技术扩散中高校教师特征、流动模式、国际流动区域进行统计分析.结果表明,柔性流动以工作经历丰富、男性和高级职称教师为主;产业间流动以委托项目、项目协作等短期模式为主,产业内流动以学术组织兼职为主,国际流动区域主要... 相似文献
185.
张鸿彦 《国防交通工程与技术》2008,6(4):12-15
在论述部队摩托化机动交通保障的定义、范围和种类的基础上,阐述了其交通保障的原则、组织领导及任务要求,指出了该交通保障应有的工作程序,并提出了搞好交通保障工作相关的对策措施,力求推动该项工作的落实。 相似文献
186.
[Objective]To meet the efficient thermal management needs of electronic devices such as ships and underwater vehicles, this study focuses on the constructal design of a tree-shaped microchannel disc heat sink with wavy walls. [Method]A design prototype of the heat sink with wavy walls is first proposed. Based on constructal theory, the amplitude and wavelength of the wavy walls are designed under the constraints of fixed heat sink volume and fixed microchannel volume by maximizing the comprehensive performance evaluation criteria (PEC) while considering both heat transfer and flow pressure drop. [Results]The results show that the wavy walls increase the heat transfer surface areas and generate vortices in their cavities, effectively reducing the maximum temperature. When the inlet Reynolds number is fixed at 700, 900 or 1100 respectively, the maximum temperature is reduced by 13.5 K by increasing the amplitude of the wavy walls, while the pressure drop increases significantly; and the maximum temperature is reduced by 4.7 K by reducing the wavelength of the wavy walls, while the pressure drop increases slightly. There are optimal amplitudes that raise the comprehensive performance evaluation criteria to extreme values for given larger wavelengths, while the comprehensive performance evaluation criteria increase monotonously as the amplitude increases for given smaller wavelengths. [Conclusion]Wavy walls can significantly improve the thermal performance of tree-shaped microchannel disc heat sinks, and the use of constructal design can realize optimal geometric constructs with optimal comprehensive performance evaluation criteria. © 2023 Authors. All rights reserved. 相似文献