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   281篇
  免费   14篇
  国内免费   69篇
航空   236篇
航天技术   45篇
综合类   70篇
航天   13篇
  2024年   1篇
  2023年   2篇
  2022年   5篇
  2021年   15篇
  2020年   8篇
  2019年   8篇
  2018年   11篇
  2017年   19篇
  2016年   15篇
  2015年   24篇
  2014年   26篇
  2013年   16篇
  2012年   22篇
  2011年   34篇
  2010年   13篇
  2009年   17篇
  2008年   13篇
  2007年   16篇
  2006年   11篇
  2005年   12篇
  2004年   13篇
  2003年   11篇
  2002年   10篇
  2001年   7篇
  2000年   13篇
  1999年   6篇
  1998年   5篇
  1997年   3篇
  1995年   3篇
  1994年   2篇
  1993年   1篇
  1989年   1篇
  1987年   1篇
排序方式: 共有364条查询结果,搜索用时 31 毫秒
361.
This paper proposes a new method for dynamic airspace configuration based on a weighted graph model. The method begins with the construction of an undirected graph for the given airspace, where the vertices represent those key points such as airports, waypoints, and the edges represent those air routes. Those vertices are used as the sites of Voronoi diagram, which divides the airspace into units called as cells. Then, aircraft counts of both each cell and of each air-route are computed. Thus, by assigning both the vertices and the edges with those aircraft counts, a weighted graph model comes into being. Accordingly the airspace configuration problem is described as a weighted graph partitioning problem. Then, the problem is solved by a graph partitioning algorithm, which is a mixture of general weighted graph cuts algorithm, an optimal dynamic load balancing algorithm and a heuristic algorithm. After the cuts algorithm partitions the model into sub-graphs, the load balancing algorithm together with the heuristic algorithm transfers aircraft counts to balance workload among sub-graphs. Lastly, airspace configuration is completed by determining the sector boundaries. The simulation result shows that the designed sectors satisfy not only workload balancing condition, but also the constraints such as convexity, connectivity, as well as minimum distance constraint.  相似文献   
362.
    
城市交通出行选择多模式条件下多种出行方式之间的出行需求关系密切,为了探讨城市居民对地铁、公交车、私家车3种出行方式出行需求之间的耦合关系及时变特征,采用时变参数向量自回归(TVP-VAR)模型,使用道路拥堵指数近似代表私家车出行量,对2个小区一个月内工作日时间地铁出行量、公交车出行量和道路拥堵指数三者的平均值进行分析。研究结果表明:地铁出行量、公交车出行量、私家车出行量三者相互作用关系针对不同的用地类型,整体影响趋势不会变化太大,影响大小在时间上存在差异;城市交通小区内居民对地铁、公交车、私家车3种出行方式的出行需求之间全天存在相互作用关系,地铁出行需求的增加会减少公交车出行需求,公交车出行需求的增加会增加地铁出行需求,而私家车出行需求的增加会增加地铁出行需求并减少公交车出行需求。研究结果有助于深入认识现阶段中国城市多模式交通出行方式之间的耦合关系,以更好地应对城市交通拥堵问题。  相似文献   
363.
《中国航空学报》2023,36(4):338-353
Reinforcement Learning (RL) techniques are being studied to solve the Demand and Capacity Balancing (DCB) problems to fully exploit their computational performance. A locally generalised Multi-Agent Reinforcement Learning (MARL) for real-world DCB problems is proposed. The proposed method can deploy trained agents directly to unseen scenarios in a specific Air Traffic Flow Management (ATFM) region to quickly obtain a satisfactory solution. In this method, agents of all flights in a scenario form a multi-agent decision-making system based on partial observation. The trained agent with the customised neural network can be deployed directly on the corresponding flight, allowing it to solve the DCB problem jointly. A cooperation coefficient is introduced in the reward function, which is used to adjust the agent’s cooperation preference in a multi-agent system, thereby controlling the distribution of flight delay time allocation. A multi-iteration mechanism is designed for the DCB decision-making framework to deal with problems arising from non-stationarity in MARL and to ensure that all hotspots are eliminated. Experiments based on large-scale high-complexity real-world scenarios are conducted to verify the effectiveness and efficiency of the method. From a statistical point of view, it is proven that the proposed method is generalised within the scope of the flights and sectors of interest, and its optimisation performance outperforms the standard computer-assisted slot allocation and state-of-the-art RL-based DCB methods. The sensitivity analysis preliminarily reveals the effect of the cooperation coefficient on delay time allocation.  相似文献   
364.
空中交通复杂性是空中交通态势的本质属性,是空中交通管制工作负荷的主要驱动因素。空中交通复杂性的科学评价是实现空中交通精细化管理的关键,也是当前空管领域研究热点。本文介绍了国内外空中交通复杂性的研究团队,梳理了空中交通复杂性与工作负荷、安全水平等相互之间的区别和联系,并详细分析了现有研究的具体研究路线。在分析新一代空中交通管理系统特征的基础上,对空中交通复杂性的未来研究趋势和方向进行了展望。  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