全文获取类型
收费全文 | 826篇 |
免费 | 45篇 |
专业分类
公路运输 | 326篇 |
综合类 | 138篇 |
水路运输 | 303篇 |
铁路运输 | 94篇 |
综合运输 | 10篇 |
出版年
2024年 | 3篇 |
2023年 | 5篇 |
2022年 | 20篇 |
2021年 | 32篇 |
2020年 | 28篇 |
2019年 | 18篇 |
2018年 | 17篇 |
2017年 | 26篇 |
2016年 | 21篇 |
2015年 | 39篇 |
2014年 | 87篇 |
2013年 | 56篇 |
2012年 | 102篇 |
2011年 | 74篇 |
2010年 | 65篇 |
2009年 | 58篇 |
2008年 | 44篇 |
2007年 | 53篇 |
2006年 | 36篇 |
2005年 | 27篇 |
2004年 | 11篇 |
2003年 | 9篇 |
2002年 | 5篇 |
2001年 | 9篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1985年 | 2篇 |
排序方式: 共有871条查询结果,搜索用时 15 毫秒
871.
The assembly and installation costs account for a large share in the overall expenditures of an offshore wind farm project. Single blade installation is suitable for large scale wind turbines due to the lower crane capability requirement and lower transportation time. By introducing active tension control on the tugger lines, an automatic single blade installation approach can accomplish operations in higher sea states, reduce the waiting-on-weather time, and improve the operational efficiency. Compared to early research, a more complicated control objective is achieved in this paper, i.e., a two-tugger-line configuration is applied to stabilize the suspended blade in three degrees of freedom during crane rotation and blade root-hub mating processes. The pulleys on the crane boom, i.e., the ends of the tugger lines, are assumed to be fixedly placed, resulting in tugger line time-varying inclinations. A novel backstepping-like controller is designed and proved. It is able to stabilize the blade around its equilibrium and make it track the desired path. Sensitivity studies are conducted to evaluate the influence of the tugger line inclinations. In addition, the influence of the installed blades on a three-blade horizontal wind turbine with a monopile foundation is discussed. The proposed active control setup improves the installation success rate and reduces the risks for blade impacts that may occur during mating. 相似文献