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排序方式: 共有925条查询结果,搜索用时 265 毫秒
711.
ABSTRACTWhile automotive original equipment manufacturers and IT companies are developing and demonstrating self-driving cars, true autonomy will not be realised in the near future due in part to the technology readiness level of the existing systems as well as issues of ethics, security, governance and standards surrounding the implementation of autonomy for road transport. However, advances in cellular phones and networks, satellite-based positioning and communications, cloud computing, combined with a rise in the volumes of available data, allied with a reduction in their costs, offer the very real possibility of connecting vehicles, one to another and to smart city infrastructure as part of the Internet of Things (IoT). Data from connected vehicles, when combined with other information, may provide valuable intelligence to traffic managers and other stakeholders via cooperative intelligent transport system (C-ITS) platforms. Nevertheless, many issues face the implementation of a truly connected IoT in general and C-ITS in particular. 相似文献
712.
Sze‐Wei Chang 《先进运输杂志》2015,49(1):1-9
The runway orientation must satisfy the operational requirements of aircraft for landing and takeoff. Actually, the runway orientation is the result of compromises between the airport usability (wind coverage) and additional factors, such as available land, existing obstructions, topographic difficulties, flight path interference among runways and airports, noise pollution, and other environmental impacts. Therefore, the solution of a combination of acceptable runway orientations, which avoids excessive crosswinds at least 95% of the time, as well as the optimal orientation solution, is essential to conduct those compromises in the runway orientation analysis. The objective of this paper is to develop a computer model, named the optimization of multiple runway orientations model, which is capable of simultaneously providing a combination of acceptable runway orientations, changing the allowable crosswind limit flexibly, and determining the optimal orientations of multiple runway configurations. Instead of visual estimation or geometric computation, this paper presents an analytical method for wind coverage analysis. The model is mainly running in spreadsheet and Visual Basic for Applications (VBA). The numerical example and comparison show that the optimization of multiple runway orientations model is competitively accurate and convenient in comparison with previous ones. This paper presents an up‐to‐date model for the optimization of multiple runway orientations. By combining it with the geographic information system obstructions model, it can become an essential element of a future model for airport development cost minimization that combines airfield land use, earthwork volume, and cost estimation modules. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
713.
利用中短期验潮资料调和分析获得11个主要分潮的调和常数实现水位推算的方法,已在海洋测绘、疏浚工程测量等领域得到推广。但不进行全部站点的同步验潮测量,仅收集不同期历史验潮数据进行分析,获得的潮汐调和常数难以满足水深测量水位改正的精度要求。提出2种调和常数优化方法,通过增强不同期验潮数据调和常数的相关性,提高水位推算的精度,并以实例验证不同期验潮数据用于余水位差分水位推算的可行性。 相似文献
714.
715.
以智能车辆的MIRA简化模型作为研究对象,在自动控制的前提下,采用移动地面边界条件,对单车和队列行驶状态下的汽车外流场进行了数值模拟研究.分别获得了单车和各种行驶工况下的三辆汽车对称面的压力分布,队列行驶三辆汽车的压力分布与单车的压力分布相似,但是后两车前部的正压区明显减弱.对于等间距和不等间距2种行驶情况,改变车辆之间的距离来模拟多种状态.气动阻力的对比分析说明:队列行驶的三辆汽车,后两车的气动阻力都低于前车的气动阻力,而且平均气动阻力与单车相比均有了一定程度的降低.通过间距的改变分别进行数值模拟,获得了间距对前后行驶三辆汽车气动阻力影响的规律,为以后队列行驶的深入研究奠定了基础. 相似文献
716.
为解决隧道内衬钢管运输和拼装施工工艺难度大、效率低、对接拼装精度差和预铺设轨道等问题,同时为适应快速发展中长距离输水管线铺设问题,结合现有内衬钢管运输方法、拼装施工工艺和河西支线工程特点,设计出内衬钢管运调一体机。设计的内衬钢管运调一体机可以免除铺设轨道,具有拆装方便、施工效率高、完全自动化和拼装施工工艺简单等优点。设计中对内衬钢管运调一体机的整体结构进行有限元分析,对关键部件和走行机构的动力系统进行系统分析,优化其内部结构和设计方案,确保内衬钢管运调一体机整体结构合理,运行安全稳定,将内衬钢管运调一体机应用到河西支线工程中,钢管运输平稳可靠,对接精度高,大大提高了施工效率和质量,为内衬钢管运调一体机的生产过程安全控制、质量控制、方案可行性、成本控制和运转控制稳定提供一种新方案。 相似文献
717.
Justin S. Chang Soo Yon Cho Beom Shin Lee Yonghwan Kim Suk Kang Yun 《Transportation》2012,39(1):33-54
The total economic value for a transportation service consists of use, option, and non-use value. The use benefit is based
on a traveler’s willingness to pay for usual consumption of the service. The optional value, on the other hand, is related
to the possible use of the service for trips not yet anticipated or currently accommodated by other travel modes. The non-use
value, however, is derived from the intrinsic merit of the service, even though a trip-maker never actually or potentially
depends on the mode. A closed-ended contingent valuation method is considered for the quantification of the option and non-use
values. A survey of single- and double-bounded dichotomous choices is conducted with a case study of South Korean bus operations.
A logistic regression model and a survival analysis for the single- and double-bounded approaches, respectively, are applied.
The estimation result is examined according to the statistical property required and the behavioral validity expected. In
particular, three issues from the output are discussed. First, the results help to show the preferable framework between single-
and double-bounded surveys for addressing an individual’s option and non-use values. Second, the differences in the absolute
values of option and non-use values are compared. Thirdly, the relationship between trip-makers’ willingness to pay and the
level of service of their primary travel modes are investigated. In conclusion, the summary of research and the possibilities
for future studies are given. 相似文献
718.
Hwa-Joong KimYoung-Tae Chang Kwang-Tae KimHyo-Jeong Kim 《Transportation Research Part D: Transport and Environment》2012,17(2):97-103
This paper provides an algorithm to minimize the fixed ordering, purchase, and inventory-carrying costs associated with bunker fuel together with ship time costs; and environmental costs associated with greenhouse gas emissions. It determines the optimum ship speed, bunkering ports, and amounts of bunker fuel for a given ship’s route. To solve the problem, we use an epsilon-optimal algorithm by deriving a property. The algorithm is illustrated by applying it to typical sample data obtained and the effects of bunker prices, carbon taxes, and ship time costs on the ship speed are analyzed. The results indicate that the ship speed and CO2 emissions are highly sensitive to the factors considered. 相似文献
719.
文章介绍了黄土的主要类型及判别湿陷性黄土的方法,分析了引起路基出现不均匀沉陷现象的主要原因,提出了防止路基出现不均匀沉陷现象的措施,为公路建设者解决湿陷性黄土路基不均匀沉陷问题提供参考。 相似文献
720.