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1.
Yongliao Zou Yan Zhu Yunfei Bai Lianguo Wang Yingzhuo Jia Weihua Shen Yu Fan Yang Liu Chi Wang Aibing Zhang Guobin Yu Jihong Dong Rong Shu Zhiping He Tielong Zhang Aimin Du Mingyi Fan Jianfeng Yang Yongqing Peng 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(2):812-823
This paper describes the scientific objectives and payloads of Tianwen-1, China’s first exploration mission to Mars. An orbiter, carrying a lander and a rover, lifted-off in July 2020 for a journey to Mars where it should arrive in February 2021. A suite of 13 scientific payloads, for in-situ and remote sensing, autonomously commanded by integrated payload controllers and mounted on the orbiter and the rover will study the magnetosphere and ionosphere of Mars and the relation with the solar wind, the atmosphere, surface and subsurface of the planet, looking at the topography, composition and structure and in particular for subsurface ice. The mission will also investigate Mars climate history. It is expected that Tianwen-1 will contribute significantly to advance our scientific knowledge of Mars. 相似文献
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Chunhui Wang Yu Tian Shanguang Chen Zhiqiang Tian Ting Jiang Feng Du 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Manually controlled rendezvous and docking (manual RVD) is a challenging space task for astronauts. This study aims to identify spatial abilities that are critical for accomplishing manual RVD. Based on task analysis, spatial abilities were deduced to be critical for accomplishing manual RVD. 15 Male participants performed manual RVD task simulations and spatial ability tests (the object-manipulation spatial ability and spatial orientation ability). Participants’ performance in the test of visualization of viewpoints (which measures the spatial orientation ability) was found to be significantly correlated with their manual RVD performance, indicating that the spatial orientation ability in the sense of perspective taking is particularly important for accomplishing manual RVD. 相似文献
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Twin support vector machine(TWSVM)is a new development of support vector machine(SVM)algorithm.It has the smaller computation scale and the stronger ability to cope with unbalanced problems.In this paper,TWSVM is introduced into aircraft engine gas path fault diagnosis.The generalization capacity of Gauss kernel function usually used in TWSVM is relatively weak.So a mixed kernel function is used to improve performance to ensure that the TWSVM algorithm can better balance a strong generalization ability and a good learning ability.Experimental results prove that the cross validation training accuracy of TWSVM using the mixed kernel function averagely increases 2%.Grid search is usually applied in parameter optimization of TWSVM,but it heavily depends on experience.Therefore,the hybrid particle swarm algorithm is introduced.It can intelligently and rapidly find the global optimum.Experiments prove that its training accuracy is better than that of the classical particle swarm algorithm by 5%. 相似文献
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针对跨域空间飞行器气动参数非线性严重和具有大不确定性等特点,提出一种基于BP神经网络的飞行器离线参数辨识与在线自适应控制的方法.首先,临近空间飞行器进行风洞试验吹风得到的气动参数是典型的输入输出非线性系统,运用BP神经网络算法进行离线训练建立气动数据的辨识模型;其次,根据气动数据的辨识模型计算实时舵效变化参数,飞行器控制的增益根据舵效变化完成在线自适应调节,实现飞行器的自适应姿态控制;最后,进行数学仿真验证,结果表明,将BP神经网络应用于飞行器姿态控制中,能够实现控制参数的自适应调整,说明BP神经网络具有优良的逼近性能,最终提升了飞行器姿态控制系统的性能,提高了智能化设计水平. 相似文献
7.
Ke Du Shijie Li Ingo Leya Thomas Smith Dongliang Zhang Peng Wang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(12):4089-4098
The Kumtag meteorite strewn field was found in the Kumtag desert, 132 km south of Hami city in the Xinjiang province, China. It is an ellipse of 2.5 × 7.9 km, with a long axis extending along the northeast-southwest direction. The largest individual meteorite of the strewn field weighs about 10 kg; the smallest individual has a mass of only 27 g. In total, more than 100 individuals with a total mass of more than 180 kg were collected. The location and the distribution of the fragments suggest that the Kumtag meteoroid entered the atmosphere in the direction Northeast-Southwest. All meteorites collected in this strewn field are samples from the same unique meteorite shower. The Kumtag meteorite is an H5 ordinary chondrite with a shock stage S2, and a weathering grade W2. The cosmic ray exposure age of Kumtag is 6.7 ± 0.8 Ma, which is rather typical for H chondrites and which indicates that Kumtag was derived from the massive impact event on its parent body ~7 Ma ago. A significant amount of He has been lost during certain unknown processe(s) before the Kumtag meteorite was ejected from its parent body. 相似文献
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针对汽车驾驶室在常用高速(65~80 km/h)时,驾驶室左右晃动的振动问题,分别建立了车体、车体与板簧的系统模型,通过试验和仿真计算得到了其自由与约束状态下的振动模态分布,找到了驾驶室产生晃动的主要原因.以板簧刚度、车体刚度为变量,将约束模态分析与遗传算法相结合,对板簧和车体组成的系统进行了优化,并通过改进使常用车速下的驾驶室响应达到了舒适性要求. 相似文献