中国科学院机构知识库网格系统: 检索

The characteristics and estimation of flow through a single rough-walled fracture 期刊论文 OAI收割
JOURNAL OF HYDRODYNAMICS, 2012, 卷号: 24, 期号: 3, 页码: 315-322
作者: Liu QQ(刘青泉); Fan HG(樊红光); Liu, QQ

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fracture seepage cubic law effective hydraulic aperture non-symmetric sinusoidal fracture Rock Joints Fluid-Flow Equation Model Law

Improved TOPS about direction of arrival estimation for wideband signals (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Vibration, Structural Engineering and Measurement, ICVSEM2011, October 21, 2011 - October 23, 2011, Shanghai, China
作者: He B.

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The study about the direction-of-arrival (DOA) estimation for wideband signals is a basic topic of Signal Processing. The method called test of orthogonality of projected subspaces (TOPS) does not require initial values to form focusing matrix compared with the coherent signal subspace method (CSSM) but it has poor performance for coherent wideband signals at low signal-to-noise ratio (SNR). Based on the lack of the conventional TOPS this paper reconstructs a set of new matrices with the narrowband correlated matrices coming from the DFT decomposition of the array output and modifies the method frame of the conventional TOPS. So we get a set of reconstructed matrices with full rank corresponding to each frequency bin and which have no array aperture loss. The improved TOPS can estimate the DOA for coherent wideband sources at low SNR and enhances the performance of the conventional TOPS. Simulation results show that the improved TOPS is effective and the total performance of which is similar to the rotational signal-subspace (RSS) method. (2012) Trans Tech Publications.

An Approach to Estimate the Flow Through an Irregular Fracture 会议论文 OAI收割
Proceeding of the sixth International Conference on Fluid Mechanics (New Trends in Fluid Mechanics Research), AIP Conf. Proc. Vol. 1376., Guangzhou, China, 2011-06-30~2011-07-03
作者: Liu QQ(刘青泉); Fan HG(樊红光)

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fracture seepage cubic law effective hydraulic aperture non-symmetric sinusoidal fracture

Design of reimaging F/1.0 long-wavelength infrared optical system (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: Zhang X.; Zhang X.; Zhang X.

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A reimaging F/1.0 long-wavelength infrared optical system is proposed. The design has a flexible opto-mechanical layout. The design process is as follows. Firstly the catadioptric reimaging system consists of two reflecting mirrors and a relay lenses. Two reflecting mirrors make up of the first imaging system and are therefore free of chromatic aberrations while low dispersion lenses were used in the reimaging system so the optical system do not need achromatic design for a high image quality. Then to correct high-order aberrations resulting from large relative aperture more parameters need to be used with aspheric or diffractive surfaces due to modern optic technology development. Here aspheric is selected for easily manufacture. Finally the design is completed with the help of ZEMAX software. The effective focal length of the objective is 120mm and the field of view (FOV) is 4. The simulated final design shows adequate image quality and the modulation transfer function (MTF) is close to diffraction limit. The effect of the surrounding environmental temperature is analyzed using the concept of thermal defocusing and the thermal compensation is discussed. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Surface modification of SiC mirror by IARE method (EI CONFERENCE) 会议论文 OAI收割
7th International Conference on Thin Film Physics and Applications, September 24, 2010 - September 27, 2010, Shanghai, China
作者: Gao J.

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A method to prepare high quality SiC coating at low temperature using large aperture E-beam evaporation PVD equipment with ion assistance was developed for the surface modification of SiC mirror for space projects. This method was called Ion Assisted Reactive Evaporation (IARE). The modified SiC coating was prepared using CH4 and Si with Kaufman ion source by IARE at 300C and it had met the requirements of applications. The SiC coating prepared by this method was amorphous. It was dense homogeneous and easy to be polished. The surface modification of a SiC mirror was carried out using SiC coating by this method and achieved a fine surface modification effect. The surface roughness (rms) of the SiC substrate was reduced to 0.862nm the scattering coefficient was reduced to 2.79% and the reflectance coated with Ag film was improved simultaneously after the surface modification. The effect of surface modification using SiC coating was close to that of using Si coating. It can be drawn that this technological method to preparation SiC coating for the surface modification of SiC mirror is reasonable and effective. 2011 SPIE.

Test of an off-axis asphere by subaperture stitching interferometry (EI CONFERENCE) 会议论文 OAI收割
4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, November 19, 2008 - November 21, 2008, Chengdu, China
作者: Zheng L.-G.; Zhang X.-J.; Zhang Z.-Y.; Zhang Z.-Y.; Deng W.-J.

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A new method combined subaperture stitching with interferometry(SSI) is introduced. It can test large and off-axis aspheric surfaces without the aid of other null optics. In this paper the basic principle and theory of the technique are analyzed. The synthetical optimization stitching model and effective stitching algorithm are established based on homogeneous coordinates transformation and simultaneous least-squares method. The software of SSI is devised and the prototype for testing of large aspheres by SSI is designed and developed. An off-axis asphere with the aperture of 376mm188mm is tested by this method. For comparison and validation and the difference of PV and RMS error between them is 0.047 e and 0.006 e the asphere is also tested by null compensation.The synthesized surface profile is consistent to that ofthe entire surface from null test respectively. So it provides another quantitative measurement for testing large aspheric surfaces and off-axis aspheres besides null-compensation. 2009 SPIE.

Annular sub-aperture stitching interferometry for testing of large asphreical surfaces (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging, ISPDI 2007: Optoelectronic System Design, Manufacturing, and Testings, September 9, 2007 - September 12, 2007, Beijing, China
作者: Zheng L.-G.; Zhang X.-J.; Deng W.-J.; Wang X.-K.

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Annular subaperture stitching interferometric technology can test large-aperture and the PV and RMS of residual error of the full aperture phase distribution is 0.027 and 0.0023 high numerical aperture aspheric surfaces with high resolution the relative error of PV and RMS is -0.53% and -0.31% respectively. The results conclude that this splicing model and algorithm are accurate and feasible. So it provides another quantitive measurement for test aspheric surfaces especially for large aperture aspheres besides null-compensation. low cost and high efficiency without auxiliary null optics. In this paper the basic principle and theory of the stitching method are introduced the reasonable mathematical model and effective splicing algorithm are established based on simultaneous least-squares method and Zernike polynomial fitting. The translation errors are eliminated from each subaperture through the synthetical optimization stitching mode it keeps the error from transmitting and accumulating. The numerical simulations have been carried on by this method. As results the surface map of the full aperture after stitching is consistent to the input surface map the difference of PV error and RMS error between them is -0.0074 and -0.00052 ( is 632.8nm) respectively

Vertical-cavity surface-emitting lasers with periodic gain structure (EI CONFERENCE) 会议论文 OAI收割
作者: Wang L.; Wang L.; Wang L.; Qin L.; Sun Y.

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The periodic gain structure is used as the active region of vertical-cavity surface-emitting lasers which can enhance the effective coupling between gain regions and internal optical field. The high device performance is achieved. The maximum continuous-wave output power of large aperture device with active diameter up to 400 m is as high as 1.41 W at room temperature. The low threshold current is only 0.5 A which is lower than that of the conventional device with three quantum wells. 2006 Elsevier B.V. All rights reserved.

Magnet system for HIRFL-CSR project 期刊论文 OAI收割
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, 2002, 卷号: 12, 期号: 1, 页码: 321-324
作者: Yuan, P; He, Y; Zhang, B; Ma, LZ; He, RR

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收藏 | 浏览/下载：22/0 | 提交时间：2010/10/29

Air Circle Cooling Storage Ring Effective Aperture Field Uniformity Good Field Region

Magnet system for HIRFL-CSR project 会议论文 OAI收割
GENEVA, SWITZERLAND, SEP 24-28, 2001
作者: Wang, Y; Xiong, H; Liu, WJ; Wei, BW; Han, SF

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收藏 | 浏览/下载：15/0 | 提交时间：2018/08/20

Air Circle Cooling Storage Ring Effective Aperture Field Uniformity Good Field Region