全文获取类型
收费全文 | 134篇 |
免费 | 2篇 |
专业分类
公路运输 | 24篇 |
综合类 | 47篇 |
水路运输 | 23篇 |
铁路运输 | 25篇 |
综合运输 | 17篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 10篇 |
2013年 | 12篇 |
2012年 | 10篇 |
2011年 | 8篇 |
2010年 | 6篇 |
2009年 | 10篇 |
2008年 | 9篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 6篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
排序方式: 共有136条查询结果,搜索用时 15 毫秒
61.
北京市地铁网络拓扑结构复杂性研究 总被引:1,自引:0,他引:1
针对北京市地铁实际网络及运营关系,分别构建了SpaceL和SpaceP拓扑结构模型.基于复杂网络理论,应用现有和新的特征统计指标对两种不同的拓扑结构模型复杂性进行了分析.对SpaceL模型的研究显示,其节点度符合指数为4.1的幂律分布,满足无标度特性;其网络平均距离为15.26,连通度为0.36,代表容错性的补图效率为96.7%,说明其具备小世界网络短距离、高容错性的特点,但不同节点的补图效率显示,少量hub节点的故障会对网络造成较大损失,需重点防护.对SpaceP模型的研究显示,其网络度分布同样具有“幂律结尾”的无标度特性,幂指数为4.2;其平均距离为2.68,小于网络规模的对数(5.2),聚类系数达到0.94,具有明显的小世界特征.研究表明无论是实际网络还是运营层面上,地铁线网都具有复杂网络特征,这对进一步研究地铁线网的结构特性具有启示作用. 相似文献
62.
AbstractWaiting time influences the overall perception of service quality. The passenger-perceived waiting time can determine their waiting experience. The concept of waiting time refers to the comparison between the passengers' inherent tolerance of waiting and the possible improvement scenarios. This study investigates the passengers' tolerance of waiting under various scenarios of train delays in order to improve their perceived waiting time. We propose the adoption of a modern psychometric method utilizing the Rasch model to measure a subjective latent construct known as ‘wait tolerance'. The Rasch measurement provides mathematical procedures for transforming scores from an ordinal to an interval scale to observe which scenarios can reduce certain passengers' perceived waiting time in the case of a delay. Empirical results show that ‘uncontrollable circumstances', ‘friendly staff attitudes', and ‘providing appropriate messages of apology' can improve the passenger-perceived waiting time during train delays. Likewise, distinct differences are found in the passengers' tolerance of waiting in terms of various personal characteristics, such as gender, age, and train riding frequency. The findings propose the implementation of strategies for improvement by rail system operators, as well as for regulators to define a reasonable service level in the case of train delays. The reviews show possible future innovative research orientations as well. 相似文献
63.
64.
周松 《辽宁省交通高等专科学校学报》2008,10(2):64-65
阅读是语言运用中最频繁的一种活动.影响阅读理解的一个重要因素是词汇量,让学生苦恼的是他们的词汇量小.本文从提高学生的歧义客忍度,改善学生的注意力分配问题和讲授猜词技巧这三方面,帮助学生提高阅读速度和理解能力. 相似文献
65.
在动力学试验中发现同一类型的变阻尼转向架具有不同的动力学性能.通过建立动力学模型,应用统计分析的方法,得出转向架尺寸制造误差导致减振力变化是造成转向架动力学性能存在差异的主要原因,并给出了相应的建议. 相似文献
66.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(4):597-618
The paper investigates the use of a direct virtual sensor (DVS) to replace a physical sensor in a vehicle stability control system. A yaw control system is considered and the proposed solution can be particularly useful when a fault of the yaw rate physical sensor occurs. A DVS is a stable linear filter derived directly from input–output data, collected in a preliminary experiment. In this work, it is shown that, by using data collected in a closed-loop fashion, better DVS accuracy can be obtained with a reduced number of measured variables. Moreover, the robust stability of the closed-loop system employing a DVS is studied. The effectiveness of the presented results is shown through numerical simulations of harsh manoeuvres, performed using a detailed model of a vehicle equipped with an active front steering device. 相似文献
67.
68.
为了解决多相永磁同步电机推进系统中由于逆变器功率开关元件的短路或断路所引起的故障,根据综合矢量方法,提出了一种有效的容错控制方法;根据多相PMSM电力推进系统缺相故障后绕组的非对称分布的特点,提出了故障状态下形成圆形磁场的各相定子电流的幅值和相位条件;以12相永磁同步电动机电力推进系统为例,对最经常发生的一相及二相绕组开路故障进行容错控制仿真。仿真结果表明,容错后,转矩的原理性波动从根本上得到消除,交、直轴电流和转矩过渡过程较为平稳,过渡过程时间很短。依据仿真结果还给出了为使系统保持原有的转矩输出,容错后的各相电流幅值需增加的补偿量。 相似文献
69.
本文介绍了汽车性能分析理论,应用AVL-Cruise对单后桥驱、双后桥承载的整车动力传动系统进行建模,并模拟实际使用工况进行了动力性及经济性仿真计算,对比分析六种初选配置下整车的动力性和经济性,优选出最佳配置方案,并进行了试验验证。新建整车模型可有效地对模拟整车性能,节省设计时间。 相似文献
70.
This paper makes two contributions. It firstly proposes the use of a fault tolerance approach for railway operations and secondly it develops a minimum time gap matrix model for capacity computation and the study of perturbation effects through the generation of a compressed timetable. A fault tolerance approach is proposed to improve the operational efficiency of the railway network in terms of the network capacity and the robustness of train timetables. The term fault tolerance is used in a broad sense, to represent any abnormalities or unexpected events in operations or equipment. Enhanced fault tolerance capability provides safety assurance so that, in normal operating conditions, trains can adopt much faster speed profiles when approaching a ‘to-be-cleared’ signal block at stations and junctions than those currently permitted, effectively turning the status of ‘be ready to stop’ to that of ‘proceed with caution’. In the rare event of a ‘fault’ in the system, e.g. if a conflicting train fails to move out of a signalling block as expected or a switch fails to operate as required, the train would be re-routed to take an alternative path. In this study, the new approach is developed on three scenarios i.e., a standard classic right turn junction, a terminus station, and a small network combining both of these elements to demonstrate the performance gains, but the concept can be readily extended for other types of junctions/stations. Results so far show great potential in the proposed fault tolerance approach to increase the capacity and enhance operational robustness to perturbations at such locations. A novel method for capacity computation called minimum time gap matrix model is also introduced that has capability to produce compressed timetables directly from a given train sequence. 相似文献