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81.
Maria Daniela Graziano Marco D’Errico Elena Razzano 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
A future system integrating data from remote sensing and upcoming AIS satellites is analyzed through the development of a novel design method for global, discontinuous coverage constellations. It is shown that 8 AIS satellites suffice to guarantee global coverage and a ship location update of 50 min if the spaceborne AIS receiver has a swath of 2800 nm. Furthermore, synergic utilization of COSMO/SkyMed and Radarsat-C data would provide a mean revisit time of 7 h, with AIS information available within 25 min from SAR data acquisition. 相似文献
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As multi-discipline coupling and components interference often affect the aircraft configuration decision-making and analysis during conceptual design process, this article presents an approach of multidimensional game theory based on aircraft components to deal with this problem. The idea is that the configuration decision-making process is regarded as the game for different disciplines and technologies, and the aircraft components are players. The payoff function with highest total gain means that according to the game protocols and multidimensional theory, the optimal aircraft configuration within the strategy set will be chosen. The decision-making model is applied to conceptual design process of the high altitude long endurance (HALE) unmanned aerial vehicle (UAV) based on the assessment of technological risk. The obtained optimum configuration is quite consistent with the current HALE UAV development trends. Thus, taking into account the coupling and interference factors, the multidimensional gaming model based on aircraft components will be an effective analysis method in the decision-making process of aircraft optimum configuration. 相似文献
83.
提高飞行器升力的若干方法研究 总被引:1,自引:0,他引:1
本研究用数值模拟方法研究了四种增升方法。数据模拟的出发方程是可压流的N-S方程,格式为Beam-Warming格式的改进型。通过上述方法分别研究了:(1)动界效应对提高升力的作用;(2)涡的有利干扰对主升力面的影响;(3)吸气的驻涡增效应;(4)升力面下表面向下喷气的增升作用。研究结果表明,采用上述四种方法可有效地提高飞行器的升力,对改善飞行器的性能有着十分重要的意义。 相似文献
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轮舱火警、机翼及后下部机身的过热探测系统是飞机防火系统的重要组成部分,且故障发生频繁。本文介绍了波音737系列飞机的轮舱火警、机翼及后下部机身的过热探测系统的基本原理及常见故障,并结合外场维修经验介绍了排除该系统故障的一些技巧。 相似文献
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天基合成孔径雷达(SAR)是一种重要的主动遥感设备,在测绘、目标警戒、资源探测等方面具有独特的全天时、全天候优势。但由于低波段电磁频谱异常拥挤复杂,也容易受到其他无线电设备的非蓄意射频干扰(RFI)。本文针对工作于P、L波段的天基SAR系统,分析其常见的地面射频干扰源及其干扰机理,并构建典型的窄带与宽带干扰模型,比较分析了频域陷波、最小均方(LMS)算法、自适应线谱增强(ALE)、特征子空间分解与时频滤波等多种干扰抑制算法,并在卫星实测数据的基础上进行仿真验证抑制宽带干扰的有效性。仿真结果表明:时频滤波算法抑制宽带干扰效果最好,造成的信号损失最小,能够为后续天基合成孔径雷达的抗干扰算法设计提供决策依据。 相似文献
88.
S.P. Teng Y.K. Chen K.S. Cheng H.C. Lo 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(11):1744-1754
Remote sensing images and technologies have been widely applied to environmental monitoring, in particular landuse/landcover classification and change detection. However, the uncertainties involved in such applications have not been fully addressed. In this paper two hypothesis-test-based change detection methods, namely the bivariate joint distribution method and the conditional distribution method, are proposed to tackle the uncertainties in change detection by making decisions based on the desired level of significance. Both methods require a data set of class-dependent no-change pixels to form the basis for class-dependent hypothesis test. Using an exemplar study area in central Taiwan, performance of the proposed methods are shown to be significantly superior to two other commonly applied methods (the post-classification comparison and the image differencing methods) in terms of the overall change detection accuracies. The conditional distribution method takes into consideration the correlation between digital numbers of the pre- and post-images and the effect of the known pre-image digital number on the range of the post-image digital number, and therefore yields the highest change detection accuracy. It is also demonstrated that the class-dependent change detection is crucial for accurate landuse/landcover change detection. 相似文献
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