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排序方式: 共有153条查询结果,搜索用时 15 毫秒
101.
Mark Danby Charlie Xu 《汽车杂志》2008,(7)
赛季之前的时候大家都有一个疑问,没有牵引力控制系统的比赛会是怎么样的?来到摩纳哥的时候阴云密布,我当时就在想答案就要在这个周末揭晓了。在街道赛进行雨战,不能不说是老天的良好创意。而周日的雨战很好地回答了这个问题,而且比赛场面的精彩和不可预知性使得比赛充满悬念,非常吸引人。 相似文献
102.
This paper addresses the impacts of different scheduling alternatives for a branching transit route. It examines different schedule alternatives that might be used to optimize the route performance in terms of the passenger traveling time distributed among branch passengers and trunk‐line passengers. The schedule alternatives considered include transit vehicle allocation to different branches, offset shifting across vehicles on different branches, and vehicle holding (slack time) in the transit vehicle schedule. With these variables, several vehicle schedules are devised and examined based on a wide variety of possible passenger boarding scenarios using deterministic service models. Test outcomes provide general conclusions about the performance of the strategies. Vehicle assignment leading to even headways among branches is generally preferred for the case of low passenger demand. However, when passenger demand is high, or the differences between the passenger demands on branches are significant, unequal vehicle assignment will be helpful to improve the overall route performance. Holding, as a proactive strategy in scheduling, has the potential to be embedded into the schedule as a type of slack time, but needs further evidence and study to determine the full set of conditions where it may be beneficial. Offset shifting does not show sufficient evidence to be an efficient strategy to improve route performance in the case of low or high passenger demand. 相似文献
103.
Roxanne Warren 《先进运输杂志》1999,33(1):101-120
Ecological impacts of urban sprawl on the land, as well as forces that engender sprawl are outlined. Long-range land use priorities for more compact, transit-oriented development (TOD) are seen as ecological imperatives. While Personal Rapid Transit (PRT) could solve some congestion, it does not address these priorities. Several assumptions that underlie the PRT concept, particularly the premise that denser land use is per se socially undesirable, are challenged in terms of historical precedent. Rather, the explosive scale of ubiquitous motoring is seen as the key component of today's resistance to dense development. With peripheral parking and medium-capacity AGT links to regional transportation networks, new TOD could be redefined as pedestrian-zoned and richly landscaped urban neighborhoods; this would help resolve essential traffic and environmental barriers to its realization. The simpler automated shuttle and loop technologies are seen as more compact and potentially affordable for this purpose. Steps that could help open the way toward realization of such development are discussed. 相似文献
104.
The potential for carbon export and the role of siliceous plankton in the cycling of C and N was assessed in natural plankton assemblages in the Santa Barbara Basin, California, by examining uptake rates of inorganic carbon, nitrate and silicic acid. In April–August 1997, the concentrations of chlorophyll a, particulate organic carbon, particulate organic nitrogen and biogenic silica were measured twice monthly, and results revealed the occurrence of at least three blooms, the largest in June. Particulate elemental ratios of C, N and Si were similar to ratios of nutrient-replete diatoms, suggesting that they dominated this bloom. Mean integrated rates of carbon, nitrate and silicon uptake during the 4-month study period are similar to other productive coastal and upwelling regions (103, 8.3 and 13 mmol m−2 day−1, respectively). New production rates were twice as high as previously reported in this region and indicate that high rates of new production along eastern boundary currents are not confined to the major coastal upwelling regions. C/NO3−, Si/NO3− and Si/C uptake ratios varied widely, and mean integrated ratios were 14±5.4, 1.6±1.0 and 0.12±0.07 (S.D.), respectively. That mean C/NO3− uptake ratio corresponds to an f-ratio of about 0.5 indicating a large potential for particulate export. Based on the average Si/NO3− and Si/C uptake ratios, diatoms could perform all of the primary production and nitrate uptake that occurred during the study; these rates also suggest that export is controlled by diatoms in this system. The mean Si/C biomass ratio was lower than the mean Si/C uptake ratio, consistent with the preferential export of Si relative to C observed in sediment traps in the basin. The study took place during a period of surface-water warming, with nitrate and silicic acid concentrations decreasing throughout the onset of the 1997–1998 El Niño conditions. Although diatoms contributed less to particulate biomass during the low nutrient conditions, high f-ratios (0.33–0.66) were maintained. 相似文献
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107.
Martin Hiensch Nico Burgelman Wouter Hoeding Mark Linders Michaël Steenbergen Arjen Zoeteman 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2018,56(10):1532-1551
The extensive usage of railway infrastructure demands a high level of robustness, which can be achieved partly by considering (and managing) the track and rolling stock as one integral system with due attention to their interface. A growing number of infra managers consider, in this framework, the track-friendliness of vehicles that have access to their tracks as a key control parameter. The aim of this study is to provide further insight into potential contributions to track-friendliness, assessed in relation to track deterioration mechanisms and cost, understanding how potential benefits are best to be utilised. Six proposed freight bogie design measures are evaluated with respect to the improvement in curving behaviour, switch negotiation and related track degradation mechanisms. To this purpose a sensitivity analysis has been carried out by means of track–train simulations in the VAMPIRE® multi body simulation software. Additionally, the impact on track deterioration costs has been calculated for those track-friendly design modifications identified as most promising. Conclusions show that the standard Y25L freight bogie design displays rather a track-friendly behaviour. Tuning the primary yaw stiffness shows a high potential to further improve track-friendliness, significantly reducing track deterioration cost at narrow radius curves and switches (by, respectively, 30% and 60%). When calculating the overall deterioration cost for the travelled route, the calculation model should include a well-balanced representation of switches and narrow radius curves. 相似文献
108.
Mark T. Lusk Young-Kook Lee Herng-Jeng Jou William H. Elliott Gerard M Ludtka . Materials Science Program Division of Engineering Colorado School of Mines Golden CO. U.S. . Questek Innovations LCC Maple Avenue Evanston IL U.S. 《上海交通大学学报(英文版)》2000,(1)
QuanitativelyaccuratePredictionsofquenchinduceddistOnionandresidualstressrelyontheabilitytopredictthemicrosthectUralevolUtionthroughOutthequenchProcess.InlowaIloysteels,cUrrenresearchMshavefOcusedontheformationldneticsoffetrite,pearlite,bainiteandmartensite.However,temPeringcanhavealargeinfluenceondistOnionandresidualstrCss,andeffortstoaccountforthislagbehindthemodelingofthePrimnyphasetransihons.AsafirststeptowardsaccountingfortemPerillg,wehavedevelOpedanintemalstatevariablemodelthatuses… 相似文献
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110.
Mark E. Tompkins 《Coastal management》2013,41(2):135-155
Abstract South Carolina has a significant stock of diked coastal wetlands, dating from the days of rice culture before the Civil War. A survey of those controlling these sites along the entire South Carolina coast reveals that many continue to be used for waterfowl hunting, with management practices becoming more intensive than they were when partial data were gathered a decade ago. It also suggests that most of the acreage involved is located in large fields, where management is more difficult and mosquito control problems are more likely. This survey also indicates that public access is limited, but that there is evidence of continuing conflict over ownership. This situation creates a persisting dilemma for coastal zone management, shaping conflicts between alternative strategies for the use of natural systems. 相似文献