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排序方式： 共有989条查询结果，搜索用时 15 毫秒
741.
十多年前,有一项新科技的前景价值得到了世界电视厂商的一致认可,那就是PIP技术(画中画).PIP,简而言之就是能够在电视画面中含括一个小窗显示另一个画面,以此实现在同一时间收看两个不同的电视节目的一项技术.十多年过去了,在如今蓬勃发展的智能电视领域,这项技术几乎彻底销声匿迹,没有消费者愿意在电视上为它买单.可在移动智能... 相似文献
742.
Y. S. Pyoun H. T. Kim Y. C. Lee A. Gafurov H. Kim D. H. Jung 《International Journal of Automotive Technology》2008,9(1):61-70
Surface topology, cone angle and the forces acting on the cone of the clutch type limited slip differential (LSD) are major design parameters for the bias ratio and the noise condition. Therefore much research has been dedicated to these developments but the results have been used to submit patents. A new cone type limited slip differential for sport utility vehicles and recreational vehicles, which has a very simple structure and easy compliance with the vehicle performance, has been developed by the axiomatic approach and the ultrasonic nano crystal surface modification (UNSM) technology. The design criteria and optimal value of the design parameters are determined by the axiomatic approach utilizing CAE tools. Test methodologies in a test rig and in a vehicle were also developed. Test results showed good performance of bias ratio and noise level but durability is still under testing. This study is an extension of F2006P266, FISITA 2006. 相似文献
743.
The characteristics and interannual variability of the deep water masses in the North and Central Aegean Sea are being investigated through the data sets of the Hellenic Navy Hydrographic Service (HNHS) and the MEDATLAS 1997 project. In the period between 1987 and 1993, the densest deep water in the Mediterranean has been produced in the Aegean Sea (with σθ densities reaching up to 29.6 kg/m3), contributing to what has been called the Eastern Mediterranean Transient. The examination of time series of mean integrated values of θ, S and σθ below the depth of 500 dbar reveals the significant deep water density increase after 1987 in all of the deep basins in the area. Data suggest that the density increase of 1987–1988 is mainly attributed to a temperature drop, while in 1993, an even more intense density increase is observed, characterized this time by an abrupt salinity increase. We assume that the increased salinity necessary to produce deep water masses with the observed characteristics was not locally produced but rather advected from the Levantine through the South Aegean. After 1993, no new deep water formation episodes have been observed. A series of Θ–S diagrams derived from HNHS CTD casts covering the period between 1993 and 2000, depict the different characteristics of the deep water masses in the area. As 1993 marks the end of the formation period, observed differences between basins in that year must be attributed to different deep water formation sites. Thereafter, the stagnating deep water in the North and Central Aegean basins has been slowly gaining buoyancy by losing salt and gaining heat. The rate at which this phenomenon takes place varies between different deep basins. It is suggested that these variations are linked to the different volumes of each basin as well as to the general circulation features of the Aegean Sea. 相似文献
744.
Jonathan E. D. Richmond 《运输评论》2013,33(3):357-390
Abstract The role of a metaphor of centrally controlled air conditioning in governing Singaporean transport planning is examined, and its consequences evaluated. A modern transportation system has been put in place to link a hierarchy of central places. Tight government control has made change possible. A reliance on technical expertise at the expense of public involvement has, however, failed to develop public transport to effectively serve a range of dispersed‐destination travel needs. Regulatory approaches, furthermore, have discouraged service innovation. Policies making car purchase expensive have restricted car ownership. Effective change would be facilitated by involving a highly educated public more in decision‐making. 相似文献
745.
746.
Abstract A phenomenon new to the Polish situation—the deregulation of rail transport—is presented. Despite its primarily legal nature, deregulation also implies various economic, socio‐political and spatial consequences. The relatively short period over which partial deregulation of public transport in Poland has been in effect (i.e. since 2000) ensures that the issue has not been taken up by Polish geographers as a research field. However, it has been of interest to Polish economists. Deregulation is a phenomenon of primary importance, with direct implications for the character, quality, type, intensity and spatial differentiation of transport (including freight and passenger traffic) within the market economy. This paper, therefore, presents the impact of the recent changes in the legal system (as regards deregulation) on the current pattern of railway connections of the major carriers. As the majority of these originate beyond the Polskie Koleje Państwowe (Polish State Railways) Group, they can be said to be independent of the main former state carrier. 相似文献
747.
Brian O'Neill 《运输评论》2013,33(1):83-94
Smeed and Haddon were among the first to recognize that deaths and injuries from motor vehicle crashes were amenable to scientific study and systematic control. In the United States, the Insurance Institute for Highway Safety undertakes research on ways to reduce motor vehicle crash losses on the principles developed by these early pioneers. It communicates the scientific findings to a wide audience. Recent Institute research has shown that raising the licensing age and imposing night‐time driving curfews on the youngest drivers can substantially reduce crashes. Institute research has also been influential in leading to a law penalizing states that fail to enact a minimum purchase age of 21 for alcohol. Other Institute work demonstrating that a single, central, high‐mounted brake‐light can greatly reduce the frequency of rear‐end crashes has resulted in federal regulations requiring these lights on all new cars. Field tests of anti‐lacerative windshields have led to changes in federal regulations. Surveys of seat‐belt use under recently passed state laws show that use increases with the laws though to not nearly as high levels as in Great Britain. Long supported by Institute research, air bags are beginning to reappear in the market‐place. Insurance industry support for such activities follows a long tradition of support for loss reduction measures in many fields. 相似文献
748.
749.
Stringent regulations on exhaust emissions and fuel economy for vehicles have become major issues in the automotive industry. Hybrid electric vehicles (HEV) are one of the crucial alternative plans to current conventional vehicles, but they have drawbacks, which include increases in total hydrocarbon (THC) emission from the engine and deterioration of the combustion stability with frequent stopping and restarting of the engine. Intake port fuel film is evaporated up during the deceleration state due to the fuel-cut. The λ (relative A/F ratio) at engine restart is lean because part of injected fuel is used to form the fuel film in the intake port. This study revealed the behavior of a fuel film in engine stop with fuel-cut and in engine restart with a simulation model. To investigate the fuel film characteristics, a simulation model was applied and validated with a single-cylinder engine. The simulation result shows that λ of at least 1.2 is required for a stable engine restart. The minimum injection quantity of the first cycle for stable combustion is suggested to be at least 240% of the steady-state idle condition. 相似文献
750.
C. Jeong Y. Lee S. Choi D. Jung K. Lee 《International Journal of Automotive Technology》2013,14(1):123-132
Research and development involving intelligent vehicles of today is geared to safe, driver-friendly and sensitive vehicles that provide a driver with a pleasant and convenient driving environment while preventing him or her from possible risks of accident. In developing convenient and safe vehicles, research on drivers’ driving patterns, reactions and state characteristics depending on road conditions in actual field is essential in order to devise more driver-friendly intelligent vehicles. This paper describes how a driver-vehicle interaction (DVI) field database is built in order to obtain a driver’s input in normal road driving condition on highways, country roads, and city roads, and his or her state information, as well as data on the vehicle and traffic conditions. And the newly built database is compared with the RDCW FOT database established by UMTRI of the US for analysis to suggest that the driving tendencies of drivers in Korea and the road driving conditions are not the same as those in the US, reconfirming the need to establish a DVI field database, which will be used for the development of intelligent vehicles suitable for the Korean environment. The DVI data collected from actual driving in field are anticipated to be widely utilized as basic data for research on various intelligent driving safety systems, advanced driver assistance systems (ADAS) and human-vehicle interface (HVI) that are suitable for the driving environment in Korea. 相似文献