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排序方式: 共有108条查询结果,搜索用时 31 毫秒
51.
Daniel Salmons 《天津汽车》2008,(5):26
尽管这些年来汽车照明技术取得不小的进步,但夜间行车的风险仍比白天大得多.据美国国家公路交通安全管理局(NHTSA)的统计,虽然夜间行车在整个公路交通中只占1/4,发生的死亡事故却占了一半. 相似文献
52.
Audrey de Nazelle Daniel A. Rodríguez 《Transportation Research Part D: Transport and Environment》2009,14(4):255-263
A microsimulation of individuals’ activities is used in the context of a risk analysis framework to assess the impacts of hypothesized changes to the built environment on personal energy expenditure and on inhalation of air pollutants. Uncertainty is assessed using Monte Carlo simulations and sensitivity analyzes. We find both simulated individuals that augment and others that reduce their energy expenditure and inhalation dose of pollutants, with median increases displaying larger magnitudes than the decreases. Up to 75% of the population has significant increases in energy expenditure and pollutant inhalation. We also find, however, high uncertainty associated with the estimates. Results differ considerably depending on the travel mode choice model used in the simulation. 相似文献
53.
Ye Tian Sheng Liu William J.T. Daniel Paul A. Meehan 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2015,53(5):692-709
This paper presents the locomotive traction controller performance with respect to the track wear under different operation conditions. In particular, an investigation into the dynamic response of a locomotive under changing wheel–rail friction conditions is performed with an aim to determine the effect of controller setting on track wear. Simulation using a full-scale longitudinal–vertical locomotive dynamic model shows that the appropriately designed creep threshold, controller, settings can effectively maintain a high tractive effort while avoiding excessive rail damage due to wear, especially during acceleration under low speed. 相似文献
54.
Daniel A. Rodríguez Carlos H. Mojica 《Transportation Research Part A: Policy and Practice》2009,43(5):560-571
A before and after hedonic model is used to determine the property value impacts on properties already served by the transit system caused by extensions to Bogotá’s bus rapid transit system. Asking prices of residential properties belonging to an intervention area (N = 1407 before, 1570 after) or a control area (N = 267 before, 732 after) and offered for sale between 2001 and 2006 are used to determine capitalization of the enhanced regional access provided by the extension. Properties offered during the year the extension was inaugurated and in subsequent years have asking prices that are between 13% and 14% higher than prices for properties in the control area, after adjusting for structural, neighborhood and regional accessibility characteristics of each property. Furthermore, the appreciation is similar for properties within 500 m and properties between 500 m and 1 km of the BRT. 相似文献
55.
56.
Daniel Lancien 《先进运输杂志》1993,27(1):65-77
The development of railway transportation, especially through the gradual implementation of high-speed European network, is inciting railway companies to design railway movements command and control systems to enhance technical performance in terms of throughput and control of disturbances while simultaneously minimizing operational costs. The new command-control systems must be modular, adaptable and evolutive structures from both functional and geographical viewpoints if they are to satisfy all operational needs. Concurrent research into performance enhancement and cost reduction prescribes a system in which the majority of the “real time” components are aboards the locomotives. This is particularly true for those components used by the train to indicate its own position on the network as well as those enabling it to converse with operational control centers. The initial task is to design a global architecture of the command-control system that satisfies modularity and availability criteria followed by the development of numerous technical components including radar self-location systems and cellular radio transmission networks. The French (SNCF) and German (DB) national railways have implemented a vast program of co-operation aimed at providing valid, proven answers to these problems so as to allow their trains to travel freely on either network. 相似文献
57.
The quenching of a metal component with a channel section in a water tank is numerically simulated. Computational fluid dynamics
(CFD) is used to model the multiphase flow and the heat transfer in film boiling, nucleate boiling and convective cooling
processes to calculate the difference in heat transfer rate around the component and then combining with the thermal simulation
and structure analysis of the component to study the effect of heat transfer rate on the distortion of the U-channel component.
A model is also established to calculate the residual stress produced by quenching. The coupling fluid-thermal-structural
simulation provides an insight into the deformation of the component and can be used to perform parameter analysis to reduce
the distortion of the component. 相似文献
58.
Patrick KA EDING Daniel OLARU Masahiko FUJIKUBO 《船舶力学》2005,9(3):60-76
理想化结构单元法(ISUM)已经成为评估结构系统中承受载荷能力的一个有效工具.本文给出了最新的ISUM板元公式,并考虑了双轴向推力和横向载荷对板元的加载.为了精确地模拟加筋板的性能,分别用梁-柱元和板元制作了肋材和板材的模型.与有限元分析(FEA)的比较表明该方法对解决加筋板在横向压力和推力载荷下的问题是适用的.对箱形桁材的四点弯曲试验的分析表明与试验数据吻合良好. 相似文献
59.
We estimate spatial hedonic price functions to examine local and regional accessibility benefits of commuter rail service
in Eastern Massachusetts, while controlling for proximity-related negative externalities and other confounding influences.
The data include 1,860 single-family residential properties from four municipalities with commuter rail service, and three
municipalities without commuter rail service. We find some evidence of the capitalization of accessibility to commuter rail
stations. Two model specifications suggest that properties located in municipalities with commuter rail stations exhibit values
that are between 9.6% and 10.1% higher than properties in municipalities without a commuter rail station. With a third model
we detect weak evidence of the capitalization of auto access time or walking time to the stations, suggesting that properties
located within a one-half mile buffer of a station have values that are 10.1% higher than properties located outside of this
buffer area and that an additional minute of drive time from the station is related to a decrease of 1.6% in property values.
Our results also indicate that proximity to commuter rail right-of-way has a significant negative effect on property values,
which suggests that for every 1,000 ft. in distance from the commuter rail right-of-way, property values are between $732
and $2,897 higher, all else held equal. At the mean sample values, this result translates into an elasticity of between 0.03
and 0.13, depending on the functional form of the hedonic price equation. 相似文献
60.
Alberto Doria Sergio Daniel Roa Melo 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2018,56(6):947-966
In recent years the Whipple Carvallo Bicycle Model has been extended to analyse high speed stability of bicycles. Various researchers have developed models taking into account the effects of front frame compliance and tyre properties, nonetheless, a systematic analysis has not been yet carried out. This paper aims at analysing parametrically the influence of front frame compliance and tyre properties on the open loop stability of bicycles. Some indexes based on the eigenvalues of the dynamic system are defined to evaluate quantitatively bicycle stability. The parametric analysis is carried out with a factorial design approach to determine the most influential parameters. A commuting and a racing bicycle are considered and numerical results show different effects of the various parameters on each bicycle. In the commuting bicycle, the tyre properties have greater influence than front frame compliance, and the weave mode has the main effect on stability. Conversely, in the racing bicycle, the front frame compliance parameters have greater influence than tyre properties, and the wobble mode has the main effect on stability. 相似文献