全文获取类型
收费全文 | 309篇 |
免费 | 16篇 |
专业分类
公路运输 | 81篇 |
综合类 | 156篇 |
水路运输 | 51篇 |
铁路运输 | 18篇 |
综合运输 | 19篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 9篇 |
2015年 | 13篇 |
2014年 | 18篇 |
2013年 | 18篇 |
2012年 | 32篇 |
2011年 | 34篇 |
2010年 | 20篇 |
2009年 | 12篇 |
2008年 | 21篇 |
2007年 | 27篇 |
2006年 | 25篇 |
2005年 | 17篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 3篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1998年 | 1篇 |
1993年 | 2篇 |
1989年 | 1篇 |
排序方式: 共有325条查询结果,搜索用时 203 毫秒
61.
传统自动驾驶车辆以假设通行权为前提设计冲突消解算法,但在无信号交叉口存在道路通行权不明确情况,给自动驾驶车辆决策带来困扰.本文提出基于多车协作优化的无信号交叉口冲突消解方法,将多个自动驾驶车辆看成一个整体,利用多目标优化控制理论,计算分配给相互冲突车辆的期望速度规划,达到协作行驶的目的.设置协作与非协作式冲突消解仿真实验.结果表明:多车协作的冲突消解方法通过优化车辆联合行动,使交叉口车辆整体收益最大,各利益体间的收益更为均衡;与非协作行驶决策相比,冲突消解时间缩短,减少交叉口单车平均延误1~2 s,平均减少量约为5%.本文可为无信号交叉口自动驾驶车辆冲突时自主协同行驶提供参考. 相似文献
62.
63.
以使用维修为切入点,阐述帕萨特领驭轿车定速巡航控制系统的组成、控制原理、对系统进行电路分析,基于电路分析给出维修思路和故障案例。 相似文献
64.
Traffic conflict under congested conditions is one of the main safety issues of motorcycle traffic in developing countries. Unlike cars, motorcycles often display non-lane-based movements such as swerving or oblique following of a lead vehicle when traffic becomes congested. Very few studies have quantitatively evaluated the effects of such non-lane-based movements on traffic conflict. Therefore, in this study we aim to develop an integrated model to assess the traffic conflict of motorcycles under congested conditions. The proposed model includes a concept of safety space to describe the non-lane-based movements unique to motorcycles, new features developed for traffic conflict assessment such as parameters of acceleration and deceleration, and the conditions for choosing a lead vehicle. Calibration data were extracted from video clips taken at two road segments in Ho Chi Minh City. A simulation based on the model was developed to verify the dynamic non-lane-based movements of motorcycles. Subsequently, the assessment of traffic conflict was validated by calculating the probability of sudden braking at each time interval according to the change in the density of motorcycle flow. Our findings underscore the fact that higher flow density may lead to conflicts associated with a greater probability of sudden breaking. Three types of motorcycle traffic conflicts were confirmed, and the proportions of each type were calculated and discussed. 相似文献
65.
66.
67.
68.
Most existing media access control (MAC) protocols in power line communication (PLC) networks just discard the colliding data
packets when collision occurs. The collision deteriorates throughput and delay performance of system under high traffic conditions.
This article presents a novel media access scheme with fast collision resolution for in-home power line networks. It works
by first recognizing the colliding stations through detecting the inserted unique ID sequence ahead of data packets, then
the source nodes retransmitting their packets immediately after the collision slot. The proposed protocol maintains the benefits
of ALOHA systems. It needs no scheduling overhead and is suitable for bursty sources, such as multimedia data packets. Computer
simulations have demonstrated that this approach can achieve high throughput due to its ability of resolving collisions. 相似文献
69.
在理解域名解析系统(DNS)的基础上,阐明了在当前网络应用中DNS系统所存在的一些缺陷,如不支持数据的移动和复制,负载不均衡等.本文设计了全新的名字解析映射系统来克服这些缺陷,并把它应用在一体化网络中.该名字解析映射系统采用三层重叠网络结构:中继层、实现层和维护层,中继层控制用户接入,实现层和维护层协同工作,实现名字的解析映射.理论分析和试验结果表明,该设计克服了域名解析系统存在的缺陷,将在一体化网络的设计中起到重要作用. 相似文献
70.
介绍了Multi—Agent系统在飞行冲突探测与解脱中的具体应用,将航空器看作具有各自目标如目的地、到达时间和服务标准等的智能体,提出采用协作式多智体协商技术来有效解决冲突问题,并建立了基于Multi—Agent系统的飞行冲突探测与解脱模型。航空器Agent之间可通过航空器数据链通信,采用单调让步协议(MCP)协商,自动就冲突解脱方案达成一致,在保证安全间隔的同时实现空域容量的有效利用。 相似文献