美国冲压发动机研制概况

本文所介绍美国冲压发动机研制情况是79年3～4月我国燃气轮机和空气喷气发动机热物理代表团在美国参现访问总结报告的一部分内容。     

A memetic algorithm for path planning of curvature-constrained UAVs performing surveillance of multiple ground targets

The problem of generating optimal paths for curvature-constrained unmanned aerial vehicles （UAVs） performing surveillance of multiple ground targets is addressed in this paper. UAVs are modeled as Dubins vehicles so that the constraints of UAVs＇ minimal turning radius can be taken into account. In view of the effective surveillance range of the sensors equipped on UAVs, the problem is formulated as a Dubins traveling salesman problem with neighborhood （DTSPN）. Considering its prohibitively high computational complexity, the Dubins paths in the sense of terminal heading relaxation are introduced to simplify the calculation of the Dubins distance, and a boundary-based encoding scheme is proposed to determine the visiting point of every target neighborhood. Then, an evolutionary algorithm is used to derive the optimal Dubins tour. To further enhance the quality of the solutions, a local search strategy based on approximate gradient is employed to improve the visiting points of target neighborhoods. Finally, by a minor modification to the individual encoding, the algorithm is easily extended to deal with other two more sophisticated DTSPN variants （multi-UAV scenario and multiple groups of targets scenario）. The performance of the algorithm is demonstrated through comparative experiments with other two state-of-the-art DTSPN algorithms identified in literature. Numerical simulations exhibit that the algorithm proposed in this paper can find high-quality solutions to the DTSPN with lower computational cost and produce significantly improved performance over the other algorithms.     

RQ-180隐身无人侦察机初露端倪

美国《航空周刊》基于近年来美国装备建设领域出现的一些蛛丝马迹,于2013年12月9日披露,诺斯罗普·格鲁门（诺格）公司正在为美国空军研制和试飞一种新型隐身无人机平台,并将其称之为RQ-180。目前,美国空军和诺格公司都对此事三缄其口,至于这种无人机何时会公之于众更是一个未知数。尽管如此,这篇报道还是引发了世界各国对于美国新型无人机的高度关注。     

SR-72无人机的研制进展

据国外媒体报道，洛克希德·马丁公司近日披露了SR-72双发隐形无人机的研制情况。其飞行马赫数可达6，是著名的SR-71“黑鸟”战略侦察机最大飞行速度的2倍，预计在2018年公开展示。     

支线客机关键技术与发展方向

支线航空作为公共运输航空的一个重要组成部分，随着市场需求的激增和国家政策的扶持，即将进入高速发展期。支线客机作为支线航空市场中的核心技术产品，不仅是打开全球支线飞机市场的钥匙，更是体现大国经济和科技实力的重要名片。基于支线客机的发展历程，深刻剖析了支线客机的任务使命，对支线客机总体气动、动力、机载系统这3方面的关键技术进行了详细阐述，并结合商用飞机的发展，讨论了支线客机的技术发展方向；最后基于未来发展需求，提出了基于自动、自主和智能化的支线客机任务系统概念。