电力电子装置在混合电动汽车中的应用

混合电动汽车由于其性能和经济上的优势,比纯电动汽车得到更多的用户认可.现在全球两大汽车公司在世界上大多数地区销售的混合电动汽车累计超过12万辆.尽管纯电动汽车在道路运输和短途交通中可得到适当应用,但与非混合的汽车相比,混合电动汽车非常实用,燃料可节省5%～50%,甚至更多.现在由于交流传动使用寿命长,易于采用电力电子控制,它普遍用于混合动力系.但是,因为汽车推进系统独特的应用要求,目前的交流传动还难以满足整个驱动系统性能要求,且达不装置的体积目标.所以,目前混合动力系仍然使用容量过大的电机或电力电子装置的交流传动.本文基于这样的前提:解决混合电动汽车交流传动的宽恒功速比(CPSR)和整体性能最经济的办法是建立在电力电子装置基础上的.文章主要介绍变速装置方面的现状,以及为了提供与客运汽车更好匹配的交流传动装置正在作哪些努力.     

Suitability of Decision-Theoretic Models to Public Policy Issues Concerning the Provision of Shoreline Stabilization and Hazard Management

This article examines the suitability and potential advances of decision-theoretic models from finance regarding investment decisions in shoreline stabilization projects. A set of scenarios represents the dynamics of the decision-state facing the planner and identifies factors that should be incorporated into the decision-making process. It is shown that decision models from finance can account for the risk and uncertainty inherent in shoreline stabilization projects, potentially suggest improvements and refinements to presently used cost-benefit analysis procedures, and offer new tools that can aid in decisions concerning provision of shoreline stabilization. The outcomes of these scenarios justify better planning and control of existing and future building, and that of poststorm policies. Lastly, these models allow us to explore the range of our understanding of coastal processes and interactions with shoreline stabilization projects and can identify new and useful data needed in coastal management and hazard management decisions.     

仍然梦着

是我爸教我认识加利福尼亚。小时候家里买了一台冰箱,品牌就是California,我爸说,这冰箱是美国产,叫加利福尼亚,美国一个州的名字。     

Short trips: An opportunity for reducing mobile-source emissions?

This paper examines how conversion of automobile trips of less than 3 miles to other transportation modes reduces emissions. Short trips contribute disproportionately to emissions because of cold starts. An analysis is conducted of short-trip behavior across the US using the 1995 Nationwide Personal Transportation Survey. The data is used to develop likely scenarios of mode conversions for short trips, which are then applied to estimate emission savings using MOBILE6 cold start and running emission factors for volatile organic compounds, nitrogen oxides, carbon monoxide, and carbon dioxide. The results suggest that reducing short auto trips would modestly reduce mobile source air pollution, but emission reductions are high compared to most federally-funded surface transportation interventions aimed at improving air quality. Enhanced the community pedestrian environment to encourage short trip mode conversion also produces co-benefits such as increased physical activity and subsequent reductions in chronic diseases.     

默默的竞争者

既没有一级城市，也没有超级大港，山东省很少能像广东或江苏那样受到众人瞩目。但是人们却远远低估了山东省的重要性，Tom Miller在青岛为您报道。[编按]     

Linking an activity-based travel demand model with traffic emission and dispersion models: Transport’s contribution to air pollution in Toronto

This paper describes the development of an integrated approach for assessing ambient air quality and population exposure as a result of road passenger transportation in large urban areas. A microsimulation activity-based travel demand model for the Greater Toronto Area – the Travel Activity Scheduler for Household Agents – is extended with capabilities for modelling and mapping of traffic emissions and atmospheric dispersion. Hourly link-based emissions and zone-based soak emissions were estimated. In addition, hourly roadway emissions were dispersed at a high spatial resolution and the resulting ambient air concentrations were linked with individual time-activity patterns derived from the model to assess person-level daily exposure. The method results in an explicit representation of the temporal and spatial variation in emissions, ambient air quality, and population exposure.     

Control of traffic in residential neighborhoods: Some considerations for implementation

The effect of motor vehicles upon older neighborhoods has received increasing attention as residents of these areas seek to preserve the quality of life in their neighborhoods. In order to reduce through traffic in residential neighborhoods, numerous techniques have been developed, ranging from turn prohibitions to physical barriers. Since these measures have negative impacts on previous users of the streets, there has been substantial opposition to them. This paper reviews the major areas of conflict as revealed through court challenges.Nine court cases were identified by the researchers. In four, the court decision supported the control measures; in five, the courts decided against the actions. Six of the nine cases are reviewed in this paper. Major legal issues which are identified include the appropriate use of municipal police power, reasonableness in the exercise of police power, the integration of control measures into an overall transportation plan, appropriate consideration of emergency vehicle needs and the rights of access to property, and public participation in the decision. The authors conclude that properly planned and executed diversion strategies can be implemented and can withstand challenges by negatively affected parties.The opinions, findings, and conclusions expressed or implied in this paper are those of the authors only. They are not necessarily those of the Federal Highway Administration.     

Locating and sizing park-ride lots with interactive computer graphs

Two alternative methods for conducting a preliminary analysis of the problem of locating and sizing park-ride lots for an urban bus transit system are examined. These alternative methods are tested using a large and complex street network representing the northern half of the City of Seattle, Washington. Four design criteria are identified and an overall measure of system performance is devised. The problem is to determine the size and location of three park-ride lots that will maximize the performance of the system. The first method utilizes a computing system called LOCATOR II in an interactive graphic mode. In an experimental setting, five students use LOCATOR II to locate three park-ride lots and their solutions are found to exhibit a very high average level of performance. The second method does not involve a direct interaction with the computing system but does use LOCATOR II in a batch mode. Several students participate in three rounds of the batch mode experiment and the performance of their designs is somewhat poorer than the designs found in the interactive graphics experiment. Overall, the experimental results show that relatively inexperienced persons can find a high performance design for a reasonably complex problem quickly and inexpensively. These designs can provide a good starting point for the detailed consideration of many of the other aspects of the problem of providing a high performance bus transit service in an urban area.     

Are we there yet? Assessing smartphone apps as full-fledged tools for activity-travel surveys

Transportation - Given the limitations of traditional methods of data collection and the increased use of smartphones, there is growing attention given to using smartphone apps for activity-travel...     

Safe harbours

Steamship companies, among other commercial enterprises, have sought shelter abroad from high costs, heavy taxes and restrictive regulation. The main focus of this paper is on the ties between these 'safe harbours' and the control centres of international commerce.