首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   216篇
  免费   4篇
公路运输   77篇
综合类   12篇
水路运输   63篇
铁路运输   2篇
综合运输   66篇
  2021年   5篇
  2020年   4篇
  2019年   3篇
  2018年   5篇
  2017年   3篇
  2016年   8篇
  2015年   3篇
  2014年   8篇
  2013年   32篇
  2012年   13篇
  2011年   16篇
  2010年   12篇
  2009年   13篇
  2008年   16篇
  2007年   2篇
  2006年   4篇
  2005年   6篇
  2004年   2篇
  2003年   3篇
  2002年   3篇
  2001年   3篇
  2000年   3篇
  1999年   6篇
  1998年   8篇
  1997年   4篇
  1996年   5篇
  1995年   3篇
  1994年   6篇
  1992年   2篇
  1990年   1篇
  1989年   2篇
  1986年   2篇
  1984年   1篇
  1983年   2篇
  1981年   1篇
  1980年   3篇
  1979年   1篇
  1978年   2篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
排序方式: 共有220条查询结果,搜索用时 0 毫秒
1.
This paper examines the impact of personal and environmental characteristics on severity of injuries sustained in pedestrian–vehicle crashes using a generalized ordered probit model. The data covers 2000–2004 of pedestrian–vehicle crashes taken from police incident reports for Baltimore City and supplemented with local land use, urban form and transportation information specific to the individual crash locations. The results on personal and behavioral variables confirm previous findings. Women pedestrians involved in crashes tend to be injured less frequently than their male counterparts; children have an increased likelihood of sustaining injuries and older persons are more likely to be fatally injured. Pedestrians who cross against the traffic signal, are not in a crosswalk and are involved in a crash after dark are associated with greater injury risk. Of the built environment policy variables of interest, transit access and greater pedestrian connectivity, such as central city areas, are significant and negatively associated with injury severity. These results suggest that the environmental conditions should be given more scrutiny and be an important consideration when evaluating and planning for pedestrian safety.  相似文献   
2.
This paper discusses mathematical modeling of a ship equipped with energy-saving wing devices. Therewith, the ship is mathematically represented by an elongated...  相似文献   
3.
Transportation - Predicting how changes to the urban environment layout will affect the spatial distribution of pedestrian flows is important for environmental, social and economic sustainability....  相似文献   
4.
This article considers the optimisation of the sequence for clearing snow from stretches of the manoeuvring area of an airport. This issue involves the optimisation of limited resources to remove snow from taxiways and runways thereby leaving them in an acceptable condition for operating aircraft. The airfield is divided into subsets of significant stretches for the purpose of operations and target times are established during which these are open to aircraft traffic. The document contains several mathematical models each with different functions, such as the end time of the process, the sum of the end times of each stretch and gap between the estimated and the real end times. During this process, we introduce different operating restrictions on partial fulfilment of the operational targets as applied to zones of special interest, or relating to the operation of the snow‐clearing machines. The problem is solved by optimisation based on linear programming. The article gives the results of the computational tests carried out on five distinct models of the manoeuvring area, which cover increasingly complex situations and larger areas. The mathematical model is particularised for the case of the manoeuvring area of Adolfo Suarez Madrid—Barajas Airport. Copyright © 2016 John Wiley & Sons, Ltd.
    Highlights
  • Optimal sequence for clearing snow from the manoeuvring area of an airport.
  • Contains optimising algorithms solved using CPLEX LP‐based tree search.
  • Restrictions on partial fulfilment of operational targets applied to subsets of significant stretches, used for planning the operation of snow‐clearing machines.
  • Model applied to the case of the manoeuvring area of Adolfo Suárez Madrid Barajas Airport.
  • Conclusions are given on the results of the computational tests carried out. There are five models of the manoeuvring area which cover increasingly complex situations and larger areas.
  相似文献   
5.
Abstract

Over the past few years an unusually intense struggle over the future of the Lake Michigan fishery has occurred in the coastal communities of Racine and Kenosha. This struggle has engaged participants on the local, state, and national levels in the debate over the fishery as it is potentially impacted by the presence of environmental toxins, the rising cost of fish stocking and management, and conflicting user group demands. We describe three cases where urban sports anglers, with the assistance of university based social scientists, participated in state and city public policy decisions. After discussing this research and its policy implications, we propose a general public participation paradigm termed the Reciprocal Development Model.  相似文献   
6.
In the presence of biofilms, stainless steels (SS) exhibits an increase in corrosion potential, called ennoblement. In the present study, the corrosion potential (Eco,) behavior of the duplex SS UNS S32760 was recorded simultaneously with the in situ marine biofilm formation in two areas at Arraial do Cabo, Southeastern Brazil. The biofilm at Forno Harbor (an anthropogenically disturbed area) was characterized by higher relative abundances of Bacteria at day 2, followed by diatoms (especially Navicula sp.) on day 10 and dinoflagellates on day 18, whereas no clear trend was recorded at Cabo Frio Island (an undisturbed area). The ennoblement of Ecor values was site-dependent. In a complementary laboratory assay, biofilms were removed and the Eco values registered in sterile conditions for the subsequent 10 days and corroborated in situ results. Understanding biofilms and SS interactions has important implications for materials science and engineering decisions as well as helping to fill in imnortant gaps in this knowledge.  相似文献   
7.
Dual extended Kalman filter for vehicle state and parameter estimation   总被引:2,自引:0,他引:2  
The article demonstrates the implementation of a model-based vehicle estimator, which can be used for combined estimation of vehicle states and parameters. The estimator is realised using the dual extended Kalman filter (DEKF) technique, which makes use of two Kalman filters running in parallel, thus 'splitting' the state and parameter estimation problems. Note that the two problems cannot be entirely separated due to their inherent interdependencies. This technique provides several advantages, such as the possibility to switch off the parameter estimator, once a sufficiently good set of estimates has been obtained. The estimator is based on a four-wheel vehicle model with four degrees of freedom, which accommodates the dominant modes only, and is designed to make use of several interchangeable tyre models. The paper demonstrates the appropriateness of the DEKF. Results to date indicate that this is an effective approach, which is considered to be of potential benefit to the automotive industry.  相似文献   
8.
9.
The objective is to find slamming-induced local stresses in the steel or aluminum wetdeck of a multihull vessel. This is studied theoretically by representing the wetdeck as a beam model and accounting for dynamic hydroelastic effects. Two numerical methods are used, one being a simplified asymptotic solution. Satisfactory agreement between the two methods is reported. Experimental drop tests of horizontal elastic plates of steel and aluminum are also reported, and the results from the experiments agree well with the numerical computations. This study reveals, both numerically and experimentally, that slamming-induced local stresses are strongly influenced by dynamic hydroelastic effects. The maximum bending stresses are insensitive to where waves hit, the curvature of the waves, and maximum pressures. Measured maximum pressures are very sensitive to external conditions, and cannot be used as a measure of maximum local bending stresses. A simple procedure for local design stresses due to wetdeck slamming is outlined.  相似文献   
10.
Most transit agencies require government support for the replacement of their aging fleet. A procedure for equitable resource allocation among competing transit agencies for the purpose of transit fleet management is presented in this study. The proposed procedure is a 3-dimensional model that includes the choice of a fleet improvement program, agencies that may receive them, and the timing of investments. Earlier efforts to solve this problem involved the application of 1- or 2-dimensional models for each year of the planning period. These may have resulted in suboptimal solution as the models are blind to the impact of the fleet management program of the subsequent years. Therefore, a new model to address a long-term planning horizon is proposed. The model is formulated as a non-linear optimization problem of maximizing the total weighted average remaining life of the fleet subjected to improvement program and budgetary constraints. Two variants of the problem, one with an annual budget constraint and the other with a single budget constraint for the entire planning period, are formulated. Two independent approaches, namely, branch and bound algorithm and genetic algorithm are used to obtain the solution. An example problem is solved and results are discussed in details. Finally, the model is applied to a large scale real-world problem and a detailed analysis of the results is presented.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号