全文获取类型
收费全文 | 118篇 |
免费 | 0篇 |
专业分类
公路运输 | 49篇 |
综合类 | 15篇 |
水路运输 | 20篇 |
铁路运输 | 7篇 |
综合运输 | 27篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 7篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 1篇 |
2012年 | 2篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 7篇 |
2008年 | 6篇 |
2007年 | 4篇 |
2006年 | 10篇 |
2005年 | 6篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有118条查询结果,搜索用时 31 毫秒
81.
机舱通风系统是自升式风电平台重要的动力辅助系统。本文研究了具有自升式风电平台特色的机舱通风系统,对机械进风自然排风与机械进排风两种通风方式进行分析比较,并提出了先进的变频控制机舱通风系统设计理念。通过正在建造中的项目实例,详细介绍了基于变频控制的机舱通风系统的核心设计思路,展现了该系统智能、节能和安全可靠等诸多优势,对今后自升式风电平台机舱通风系统设计具有重要的指导意义。 相似文献
82.
83.
Subasish Das Bradford K. Brimley Tomás E. Lindheimer Michelle Zupancich 《国际交通安全学会研究报告》2018,42(3):143-151
Most of the information necessary for driving a vehicle is regarded as visual information. In spite of its importance, visibility conditions at the time of a crash are often not documented at a high level of detail. Past studies have not examined the quantified values of visibility and its association with crashes. The current study merged data collected from the National Oceanic and Atmospheric Administration (NOAA) with 2010–2012 Florida crash data. From the thousands of logged weather events compiled by the NOAA, the researchers isolated periods of normal visibility and comparable periods of reduced visibility in a matched-pairs study. The NOAA data provided real visibility score based on the spatiotemporal data of the crashes. Additionally, the crash data, obtained from Roadway Information Database (RID), contains several geometric and traffic variables that allow for effects of factors and visibility. The study aims to associate crash occurrence under different levels of visibility with factors included in the crash database by developing ordinal logistic regression. The intent is to observe how different visibility conditions contribute to a crash occurrence. The findings indicate that the likelihood of a crash increase during periods of low visibility, despite the tendency for less traffic and for lower speeds to prevail during these times. The findings of this study will add valuable knowledge to the realm of the impact of visibility in the way of using and designing appropriate countermeasures. 相似文献
84.
Active Traffic Management (ATM) systems have been emerging in recent years in the US and Europe. They provide control strategies to improve traffic flow and reduce congestion on freeways. This study investigates the feasibility of utilizing a Variable Speed Limits (VSL) system, one key part of ATM, to improve traffic safety on freeways. A proactive traffic safety improvement VSL control algorithm is proposed. First, an extension of the METANET (METANET: A macroscopic simulation program for motorway networks) traffic flow model is employed to analyze VSL’s impact on traffic flow. Then, a real-time crash risk evaluation model is estimated for the purpose of quantifying crash risk. Finally, optimal VSL control strategies are achieved by employing an optimization technique to minimize the total crash risk along the VSL implementation corridor. Constraints are setup to limit the increase of average travel time and the differences of the posted speed limits temporarily and spatially. This novel VSL control algorithm can proactively reduce crash risk and therefore improve traffic safety. The proposed VSL control algorithm is implemented and tested for a mountainous freeway bottleneck area through the micro-simulation software VISSIM. Safety impacts of the VSL system are quantified as crash risk improvements and speed homogeneity improvements. Moreover, three different driver compliance levels are modeled in VISSIM to monitor the sensitivity of VSL effects on driver compliance. Conclusions demonstrated that the proposed VSL system could improve traffic safety by decreasing crash risk and enhancing speed homogeneity under both the high and moderate compliance levels; while the VSL system fails to significantly enhance traffic safety under the low compliance scenario. Finally, future implementation suggestions of the VSL control strategies and related research topics are also discussed. 相似文献
85.
针对变刚度半主动悬架这种时变的、非线性复杂系统,提出将神经网络自适应控制策略用于该悬架的控制,研究中主要用车身垂直加速度作为主要控制目标,以提高车辆行驶的平顺性,同时在仿真控制研究中兼顾悬架动挠度和车轮动载荷的变化,以提高车辆行驶安全性和操纵稳定性,通过仿真计算和结果分析验证了其可行性和有效性。 相似文献
86.
高速公路可变限速系统的社会经济影响评价 总被引:1,自引:0,他引:1
运用计算机对高速公路典型路段可变限速系统进行模拟,模拟结果表明在交通量等于或大于2800veh h出现明显的效益。根据行程时间和实际服务流量确定不同交通量情况下可变限速的最佳值,并基于行程时间的节省测度出各交通量条件下实施可变限速货币化的增量效益,进行了成本效益分析。采用DEA方法进行多目标综合评价,评价结果显示,在DEA的各方案中3200、3400、3600、3800veh h所对应的DMU是DEA有效的。本文还证明了DEA对ITS项目评价是很有适用价值的,它能够描述用货币单位难以测度,但可用某种定量指标表述的重要影响。 相似文献
87.
88.
89.
90.
汽车变截面板簧轧机伺服控制系统分析及应用 总被引:1,自引:0,他引:1
分析了近年研制的BKD系列程控汽车变截面板簧轧机的伺服系统,该系统与一般轧钢机的电液伺服系统不同,其特点是行程大,要求反应快及液压流量大,结合变截面轧机实际运行情况进行分析,汽车变截面板簧轧机的特点是在轧制过程中能使轧件的断面按照板簧设计曲线要求变化。 相似文献