中国科学院机构知识库网格系统: 检索

Engineering perspective on bird flight: Scaling, geometry, kinematics and aerodynamics 期刊论文 OAI收割
PROGRESS IN AEROSPACE SCIENCES, 2023, 卷号: 142, 页码: 47
作者: Liu, Tianshu; Wang, Shizhao; Liu, Hao; He, Guowei; He GW(何国威)

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收藏 | 浏览/下载：31/0 | 提交时间：2024/01/22

Bird Flight Scaling Flapping wing Airfoil Wing geometry Wing kinematics Aerodynamics Vortex Lift Drag Thrust Thin-airfoil theory Lifting-line theory Wake models Kutta-Joukowski theorem Actuator disk model Vortex ring model CFD Multiple joint arm system

Affine Spinor Decomposition in Three-Dimensional Affine Geometry 期刊论文 OAI收割
ACTA MATHEMATICA SCIENTIA, 2022, 页码: 35
作者: Wu, Chengran; Li, Hongbo

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收藏 | 浏览/下载：24/0 | 提交时间：2023/02/07

spin group spinor decomposition affine transformation line geometry affine line reflection

Minimal Case Relative Pose Computation Using Ray-Point-Ray Features 期刊论文 OAI收割
IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE, 2020, 卷号: 42, 期号: 5, 页码: 1176-1190
作者: Zhao, Ji; Kneip, Laurent; He, Yijia; Ma, Jiayi

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收藏 | 浏览/下载：43/0 | 提交时间：2020/06/02

Three-dimensional displays Transmission line matrix methods Cameras Pose estimation Feature extraction Geometry Computer vision Structure-from-motion visual odometry minimal relative pose automatic solver generation Grobner bases ray-point-ray structures

Closed form of the inverse Plucker correspondence in line geometry 期刊论文 OAI收割
SCIENCE CHINA-MATHEMATICS, 2019, 卷号: 62, 期号: 12, 页码: 2617-2630
作者: Dong, Lei; Li, Hongbo; Huang, Lei; Shao, Changpeng

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收藏 | 浏览/下载：26/0 | 提交时间：2020/05/24

Plucker correspondence inverse Plucker correspondence line geometry SL(4) SO(3,3)

Matrices of SL that are the Product of Two Skew-Symmetric Matrices 期刊论文 OAI收割
ADVANCES IN APPLIED CLIFFORD ALGEBRAS, 2017, 卷号: 27, 期号: 1, 页码: 475-489
作者: Dong, Lei; Huang, Lei; Shao, Changpeng; Wen, Yong

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收藏 | 浏览/下载：22/0 | 提交时间：2018/07/30

Oriented projective geometry Line geometry SL(4, R) Product of two skew-symmetric matrices SL(4, R)-Jordan form

A method of plane geometry primitive presentation 会议论文 OAI收割
International Symposium on Optoelectronic Technology and Application 2014, Beijing, China, May 13-15, 2014
作者: Jiao AB(焦安波); Luo HB(罗海波); Chang Z(常铮); Hui B(惠斌)

收藏 | 浏览/下载：30/0 | 提交时间：2014/12/29

Plane geometry primitive presentation Intersecting line primitive Blob primitive Line feature Target description

Robust determination of mass attenuation coefficients of materials with unknown thickness and density 期刊论文 OAI收割
RADIATION PHYSICS AND CHEMISTRY, 2014, 卷号: 100, 页码: 65-69
作者: Kurudirek, M; Medhat, ME

收藏 | 浏览/下载：14/0 | 提交时间：2016/04/08

Mass attenuation coefficient X-ray line Beer-Lambert law Transmission geometry

Research on infrared dim-point target detection and tracking under sea-sky-line complex background (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Infrared Imaging and Applications, May 24, 2011 - May 24, 2011, Beijing, China
作者: Dong Y.-X.; Zhang H.-B.; Li Y.; Li Y.; Li Y.

收藏 | 浏览/下载：109/0 | 提交时间：2013/03/25

Target detection and tracking technology in infrared image is an important part of modern military defense system. Infrared dim-point targets detection and recognition under complex background is a difficulty and important strategic value and challenging research topic. The main objects that carrier-borne infrared vigilance system detected are sea-skimming aircrafts and missiles. Due to the characteristics of wide field of view of vigilance system the target is usually under the sea clutter. Detection and recognition of the target will be taken great difficulties.There are some traditional point target detection algorithms such as adaptive background prediction detecting method. When background has dispersion-decreasing structure the traditional target detection algorithms would be more useful. But when the background has large gray gradient such as sea-sky-line sea waves etc.The bigger false-alarm rate will be taken in these local area.It could not obtain satisfactory results. Because dim-point target itself does not have obvious geometry or texture feature in our opinion from the perspective of mathematics the detection of dim-point targets in image is about singular function analysis.And from the perspective image processing analysis the judgment of isolated singularity in the image is key problem. The foregoing points for dim-point targets detection its essence is a separation of target and background of different singularity characteristics.The image from infrared sensor usually accompanied by different kinds of noise. These external noises could be caused by the complicated background or from the sensor itself. The noise might affect target detection and tracking. Therefore the purpose of the image preprocessing is to reduce the effects from noise also to raise the SNR of image and to increase the contrast of target and background. According to the low sea-skimming infrared flying small target characteristics the median filter is used to eliminate noise improve signal-to-noise ratio then the multi-point multi-storey vertical Sobel algorithm will be used to detect the sea-sky-line so that we can segment sea and sky in the image. Finally using centroid tracking method to capture and trace target. This method has been successfully used to trace target under the sea-sky complex background. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Global view of dayside magnetic reconnection with the dusk-dawn IMF orientation: A statistical study for Double Star and Cluster data 期刊论文 OAI收割
Geophysical Research Letters, 2007, 卷号: 34, 期号: 20, 页码: L20101
Pu, Z. Y.; Zhang, X. G.Wang, X. G.; Wang, J.; Zhou, X. Z.; Dunlop, M. W.; Xie, L.; Xiao, C. J.; Zong, Q. G.; Fu, S. Y.; Liu, Z. X.; Carr, C.; Ma, Z. W.; Shen, C.; Lucek, E.; Reme, H.; Escoubet, P.

收藏 | 浏览/下载：30/0 | 提交时间：2014/04/30

earths magnetopause field magnetosphere performance instrument location geometry motion model line

Raman spectra and phonon modes of MgxZn1-xO alloy films (EI CONFERENCE) 会议论文 OAI收割
12th International Conference on II-VI Compounds, September 12, 2005 - September 16, 2005, Warsaw, Poland
Wei Z. P.; Lu Y. M.; Shen D. Z.; Zhang Z. Z.; Wu C. X.; Zhang J. Y.; Yao B.; Fan X. W.

收藏 | 浏览/下载：22/0 | 提交时间：2013/03/25

Hexagonal MgxZn1-xO alloy layers with 0 &le 0.3 have been grown by plasma-assisted molecular beam epitaxy on sapphire (006) and Si (111) substrates. Their crystal structures are characterized by x-ray diffraction spectroscopy. The nonresonant and resonant Raman spectra were measured using 488 nm line from Ar+ laser and 325 nm line from He-Cd laser by backscattering geometry. Four Raman modes (E2 high LO TO multiphonon processes) were observed in the nonresonant Raman spectra of hexagonal MgxZn1-xO with different Mg contents. The optical phonon frequencies were found to display one-mode behaviour for all the samples since no separate ZnO- and MgO-like modes were observed. The long-wavelength frequencies of ZnO-like optical phonons measured in the resonant Raman spectra can be expressed as linear functions of x. These behaviours can be explained within a modified random-element-isodisplacement model (MREI). 2006 WILEY-VCH Verlag GmbH Co. KGaA.