全文获取类型
收费全文 | 417篇 |
免费 | 5篇 |
专业分类
公路运输 | 116篇 |
综合类 | 62篇 |
水路运输 | 70篇 |
铁路运输 | 17篇 |
综合运输 | 157篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 9篇 |
2020年 | 19篇 |
2019年 | 9篇 |
2018年 | 24篇 |
2017年 | 20篇 |
2016年 | 26篇 |
2015年 | 24篇 |
2014年 | 22篇 |
2013年 | 27篇 |
2012年 | 56篇 |
2011年 | 17篇 |
2010年 | 11篇 |
2009年 | 6篇 |
2008年 | 15篇 |
2007年 | 27篇 |
2006年 | 16篇 |
2005年 | 16篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 14篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
排序方式: 共有422条查询结果,搜索用时 828 毫秒
141.
A. J. Tremlett D. J. N. Limebeer 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(10):1448-1473
Variations in track temperature, surface conditions and layout have led tyre manufacturers to produce a range of rubber compounds for race events. Each compound has unique friction and durability characteristics. Efficient tyre management over a full race distance is a crucial component of a competitive race strategy. A minimum lap time optimal control calculation and a thermodynamic tyre wear model are used to establish optimal tyre warming and tyre usage strategies. Lap time sensitivities demonstrate that relatively small changes in control strategy can lead to significant reductions in the associated wear metrics. The illustrated methodology shows how vehicle setup parameters can be optimised for minimum tyre usage. 相似文献
142.
Quantification of motorway capacity variation: influence of day type specific variation and capacity drop
下载免费PDF全文
![点击此处可从《先进运输杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Many road authorities work with static values for road capacities, while it has been proven that capacity is not a fixed quantity. At the same time, there is an increasing need for accurate stochastic input for traffic models, such as the variation in road capacity. In this paper, a methodological framework with a conceptual model for practical stochastic capacity estimation is presented, and a quantification of motorway capacity variation is given for the influence of day‐type specific variations in capacity values. The results of the analysis show that there is a reduction in motorway breakdown capacity of 4% on weekend days in comparison with workdays. Furthermore, a capacity decrease of 8% was found for the discharge capacity in comparison with workdays. The analysis further shows that the breakdown capacity on holidays is not significantly lower than on workdays. Discharge capacity and capacity drops are also derived in each case. The results show that the capacity is significantly different depending on the type of day. A quantification of these differences is given in the form of a Weibull capacity estimation fit for each type‐of‐day scenario. Further consideration of the implications and applications of the framework is also given. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
143.
144.
145.
近年来,随着中国城市化进程的不断加快,城市高架的数量也与日俱增,但高架桥在缓解交通拥堵的同时也给城市道路空气污染扩散分布带来了新的影响。为了探讨这一新问题,采用实地监测和数值模拟相结合的方法,基于计算流体力学原理(CFD)建立RNG k-ε模型及离散相(DPM)模型,分析对称型街道峡谷内高架桥沿线交通颗粒物的扩散机制。研究结果表明:高架桥的存在会影响街道峡谷内的空气流场,导致桥面颗粒物向桥下地面沉积,造成地面颗粒物浓度增大;高架引桥沿线的交通状态对街谷内湍流动能的分布也有较大影响,进而改变了颗粒物的分布状态,通过模拟发现,车辆湍动能VIT的存在使颗粒物平均浓度相比于未考虑VIT时降低了3.77%,并且加重了高架桥的“盖子效应”,使高架桥面高度以下的颗粒物的平均浓度发生变化,迎风侧浓度增长11.46%~16.52%,而背风侧浓度下降2.82%~8.65%,高架桥源颗粒物在垂直方向上更加容易扩散;同时发现,高架引桥各位置处对应的街谷内颗粒物浓度要高于高架桥面高度处的颗粒物浓度。研究成果可为制定城市高架地区的交通污染控制对策提供理论参考。 相似文献
146.
This research aims to estimate potential inter-regional passenger flows for air transport in the Middle East under open skies polices, once deregulation agreements are reached between neighboring countries. To arrive at reasonable demand estimates, Western and Eastern European demand data was analyzed as a first step, since it is assumed that current Middle Eastern demand is distorted as a direct result of regional political instability. The major factors affecting demand, based on the European dataset, included population size, gross domestic product (GDP) per capita, absolute difference in GDP per capita between two countries, great circle distance and membership of the European Union and World Trade Organization. Subsequently, a 21 country database was estimated for passenger flow in the Middle East region on an average peak season day. The demand estimations became input for a hub location model (p-hub median formulation) in order to achieve the second major aim of this research, objective identification of potential regional gateways. The results proved robust to both single and multiple allocation model assumptions, with Cairo and Tehran consistently achieving hub status, along with Istanbul and Riyadh, as the number of potential hubs increased. Finally, this research shows that under conditions of peace, given existing socio-economic indicators, inter-regional passenger demand flow could increase by upwards of 51% and regulatory authorities ought to consider the necessary infrastructure and demand management policies to enable the conservative regional demand growth estimated. 相似文献
147.
The Instrumented City (iC) database is a multi-purpose, transport-related database facility for use by the entire academic transport research community. Data from the UK Leicester City Council and Nottinghamshire County Council Traffic Management Computers is logged and archived on a continuous basis, by the Leeds University’s Institute for Transport Studies. Since its inception in 1992, the iC database has been used for various real-time applications such as air quality and noise monitoring, modelling and forecasting. This paper describes the framework that demonstrates the feasibility of using multi-agents as information analysts to process and manage the iC database. The agents are adaptive, interactive and personal. They can be trained via the interactions with the users to be personalised for individual preferences. These agents are designed to be responsible for (1) data clean-up to remove outliers; (2) missing data substitutions; (3) statistical data analysis; (4) data mining to enhance the understanding of the relationships between traffic and air quality, noise and health; and (5) knowledge discovery by identifying unknown but potentially important patterns. 相似文献
148.
Abstract As the Liquefied Natural Gas (LNG) market is supply-driven and subject to long-term contracts, both liquefaction companies and shipowners need to make strategic decisions on fleet chartering requirements. These planning decisions become ever more difficult in light of the transformations permeating the LNG market, propelling into a more competitive market with more flexible trades and expanding spot markets. The overcapacity of LNG ships during 2008–2009 triggered by massive overcontracting is a good case in point where the use of decision support models would have been beneficial, especially considering the fortunes and risks at stake. In this paper we present an LNG shipping model that effectively supports decision-making in practice. To demonstrate the value added of the model, we study the implications of LNG project delays and increased decommissioning of ships with respect to market balance and fleet requirements. 相似文献
149.
针对目前长江内贸船舶压港、滞港现象,运用灰色系统预测GM(1,1)模型对长江内贸船舶进出港艘次进行预测,进而求得未来几年内贸驾引力量需求数量。结果表明,未来几年长江内贸驾引力量需求数量巨大,驾引力量短缺严重。 相似文献
150.
This contribution presents theoretical considerations concerning the connections between life situation, lifestyle, choice
of residential location and travel behaviour, as well as empirical results of structural equation models. The analyses are
based on data resulting from a survey in seven study areas in the region of Cologne. The results indicate that lifestyles
influence mode choice, although slightly, even when life situation is controlled for. The influence of life situation on mode
choice exceeds the influence of lifestyle. The influence that lifestyle, and in part also life situation, has on mode choice
is primarily mediated by specific location attitudes and location decisions that influence mode choice, respectively. Here
objective spatial conditions as well as subjective location attitudes are important.
相似文献
Joachim ScheinerEmail: |