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排序方式: 共有81条查询结果,搜索用时 15 毫秒
1.
T_H1ANDT_H2CELLANTIGENRECEPTORSINEXPERIMENTALLEISHMANIASISStevenL.Reiner,WangZhi'en;FarahHatam,PhillipScott,RichardM.Locksley(...  相似文献   
2.
应用了电子学最新发展成果的新型柴油发动机和柴油燃料将会颠覆你以前对柴油车的所有偏见。不仅如此,它还将为汽车维修行业提供新的赢利机会。  相似文献   
3.
在我们开始了解数据网络的结构和协议时,是躲不过总线网络的,因为下一代网络可能就是快速传递数据的时代。  相似文献   
4.
Road roughness and surface texture are known to affect tire rolling resistance; however, little emphasis has been placed on the consequent changes in total vehicle energy dissipation due to road roughness. Thus, tire rolling resistance, in isolation from vehicle contributed losses such as dissipation in the suspension, appears to be a weakness in present evaluation procedures as they relate to fuel economy and pollution level testing: Recent work by Funfsinn and Korst has shown that substantial and measurable increases in energy losses occur for vehicles traveling on rough roads. The present investigation uses vehicle axle accelerations as a means of examining various road surfaces. Correlation with computer simulations has allowed the development of a deterministic road roughness model which permits the prediction of energy dissipation in both the tire and suspension as functions of road roughness, tire pressure, and vehicle speed. Comparison to the experiments of Korst and Funfsinn results in good agreement and shows that total rolling loss increases of up to 20 percent compared to ideal smooth roads are possible. The aerodynamic drag coefficient is also found to increase while driving on rough roads.  相似文献   
5.
Abstract

In southern Rhode Island, there is growing concern that housing and recreational demands will soon overwhelm the capacity of the coastal salt ponds to absorb wastes, produce seafood, and maintain scenic qualities. As a result, coastal towns have been studying the feasibility of using land controls such as downzoning to protect these coastal amenities. The paper presents an economic analysis of the downzoning program proposed in the town of South Kingstown. Hedonic price and contingent valuation methods are used to value coastal amenities. The estimated net present value of “swimmable” water is shown to be $3.1 million.  相似文献   
6.
This paper provides an analysis of trip generation of three vulnerable groups: single-parent families, low income households, and the elderly. It compares the mobility of these groups to that of the general population in three Canadian urban areas of Hamilton, Montreal and Toronto, based on data from large-sample metropolitan transport surveys. An ordered probit model with spatially expanded coefficients is used for the analysis. Spatial expansion shows that there are spatial mobility trends for elderly populations and low-income populations even after socio-economic attributes are accounted for. Such spatial differences are not generally found for single parent families. This novel spatial analysis provides clues as to where vulnerable populations may experience greater degrees of social exclusion. It provides information to help prioritize transportation infrastructure projects or other social programs to take into account the needs of vulnerable populations with the lowest levels of mobility.  相似文献   
7.
<正>本文译自美国MOTOR杂志。当我们期待着实用化的车用动力装置取代传统的汽油内燃机之时,汽车工程师们也仍在继续努力探索提高传统汽车发动机性能的方法。菲亚特公司的多气门电子控制系统算得上是最新成果的实例。  相似文献   
8.

In urban areas where transit demand is widely spread, passengers may be served by an intermodal transit system, consisting of a rail transit line (or a bus rapid transit route) and a number of feeder routes connecting at different transfer stations. In such a system, passengers may need one or more transfers to complete their journey. Therefore, scheduling vehicles operating in the system with special attention to reduce transfer time can contribute significantly to service quality improvements. Schedule synchronization may significantly reduce transfer delays at transfer stations where various routes interconnect. Since vehicle arrivals are stochastic, slack time allowances in vehicle schedules may be desirable to reduce the probability of missed connections. An objective total cost function, including supplier and user costs, is formulated for optimizing the coordination of a general intermodal transit network. A four-stage procedure is developed for determining the optimal coordination status among routes at every transfer station. Considering stochastic feeder vehicle arrivals at transfer stations, the slack times of coordinated routes are optimized, by balancing the savings from transfer delays and additional cost from slack delays and operating costs. The model thus developed is used to optimize the coordination of an intermodal transit network, while the impact of a range of factors on coordination (e.g., demand, standard deviation of vehicle arrival times, etc) is examined.  相似文献   
9.
Monse.  D 《国外铁道车辆》2000,37(5):1-7
9 一系悬挂转向架 一系悬挂转向架也叫做轴箱弹簧转向架,通常是作为提供给特种运用服务的优质转向架。在这种型式转向架上,其主弹簧和阻尼是装在轮轴系统与转向架构架之间的,因而垂向和横向弹簧挠度和阻尼与最小的簧下重量一起就直接作用于转向架轮对运动。随之带来优良的垂向和横向运行品质,以及高速蛇行稳定性和良好的曲线通过性能。 提供的这种基本结构是在运用于欧洲的转向架系列结构基础上设计的,在最新专门设计中,还结合了摆吊式横动和迫导向功能。图18为一种迫导向径向转向架。  相似文献   
10.
In this paper the long-term impact of an eco-driving training course is evaluated by monitoring driving behavior and fuel consumption for several months before and after the course. Cars were equipped with an on-board logging device that records the position and speed of the vehicle using GPS tracking as well as real time as electronic engine data extracted from the controller area network. The data includes mileage, number of revolutions per minute, position of the accelerator pedal, and instantaneous fuel consumption. It was gathered over a period of 10 months for 10 drivers during real-life conditions thus enabling an individual drive style analysis. The average fuel consumption four months after the course fell by 5.8%. Most drivers showed an immediate improvement in fuel consumption that was stable over time, but some tended to fall back into their original driving habits.  相似文献   
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