中国科学院机构知识库网格系统: 检索

Improved Capon Estimator for High-Resolution DOA Estimation and Its Statistical Analysis 期刊论文 OAI收割
IEEE/CAA Journal of Automatica Sinica, 2023, 卷号: 10, 期号: 8, 页码: 1716-1729
作者: Weiliang Zuo; Jingmin Xin; Changnong Liu; Nanning Zheng; Akira Sano

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收藏 | 浏览/下载：23/0 | 提交时间：2023/07/20

Capon beamformer direction-of-arrival (DOA) estimation large-sample mean-squared-error (MSE) subspace-based methods uniform linear array

A Family of Nonconforming Rectangular Elements for Strain Gradient Elasticity 期刊论文 OAI收割
ADVANCES IN APPLIED MATHEMATICS AND MECHANICS, 2019, 卷号: 11, 期号: 6, 页码: 1263-1286
作者: Liao, Yulei; Ming, Pingbing

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收藏 | 浏览/下载：58/0 | 提交时间：2020/01/10

Nonconforming finite elements strain gradient elasticity uniform error estimate

Characteristics of GPS positioning error with non-uniform pseudorange error 期刊论文 OAI收割
GPS SOLUTIONS, 2014, 卷号: 18, 期号: 4, 页码: 615-623
作者: Fan, Jiangtao; Ma, Guanyi

收藏 | 浏览/下载：20/0 | 提交时间：2016/11/28

Non-uniform pseudorange error GPS random positioning error Singular value decomposition Eigenvalue

Structural design of large aperture rectangular mirror for space telescope (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Civil Engineering and Transportation, ICCET 2012, October 27, 2012 - October 28, 2012, Guilin, China
作者: Li Z.; Li Z.

收藏 | 浏览/下载：43/0 | 提交时间：2013/03/25

Structural design of large aperture mirror is one of the key technologies for space telescope development. To meet the requirements of high stiffness strength and thermal dimensional stability some factors such as support scheme materials selection lightweight design and flexible support design were taken into account. The three supports location of the mirror was determined according to the modal analytical solution. By adjusting the parameters of flexure hinge influences of gravity assembly stress and thermal stress on the mirror were reduced obviously. Finite element analysis (FEA) results indicate that the surface accuracy reach to rms10.2nm and 10.8nm under the gravity along optical axis direction and 5C uniform temperature rise respectively the fundamental frequency of the mirror component is 268Hz. Dynamics test shows that the first order natural frequency is 256Hz which shows an error less than 5% compared to FEA results. (2013) Trans Tech Publications Switzerland.

Surface shape optimization for the space membrane reflector (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electronic and Mechanical Engineering and Information Technology, EMEIT 2011, August 12, 2011 - August 14, 2011, Harbin, China
作者:

收藏 | 浏览/下载：23/0 | 提交时间：2013/03/25

Space membrane reflector is very promised for optical quality application with the merits of ultra-lightweight and flexible. In order to improve the surface precision of membrane reflectors the formation and surface shape error of a membrane at uniform load are studied based on the henky-cambell equations of circular membrane. The ANSYS software is used to build an optimization model of membrane reflector surface shape in which the yield strength is the state variable the surface load on ten concentric annular regions of the mirror is the design variable and the minimum RMS between ideal surface and mirror surface is the target function. and the theoretical and experimental result show that RMS and PV of the optimized surfaces are reduced respectively than those before optimization. In a word this paper offers the theoretical and experimental basis of the polyimide membrane reflector. 2011 IEEE.

The Research of real time auto-recognition of the moire fringe (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Imaging Detectors and Applications, May 24, 2011 - May 26, 2011, Beijing, China
Wang M.-J.; Wu Z.-G.

收藏 | 浏览/下载：19/0 | 提交时间：2013/03/25

Measuring the movement of raster by the method of moire fringe has the advantage of high sensitivity high resolution and non-contacted measurement. The characteristic of moire fringe is that the image is white alternate with black the angle of the stripes is uniform the width of the stripes is uniform the terminators of the stripes aren't clear. A fast method that can figure out the width and angle of the moire fringe precisely is put forward in this paper. It calculates the angle the stripes firstly. According to the principle of the minimum mean squared error (MMSE) the closer a series of data is the smaller the value of the MMSE will be. The method is described as follows: It takes the image's center as the origin 180 beelines pass through the origin with the same angle interval. it calculates the value of the minimum mean squared error of the 180 beelines and find out the least one among those then the angle of the moire fringe comes out primarily. In order to improving the calculating precision of moire fringe 60 equal angles are divided in the neighborhood of the angle then a precise angle of moire fringe is calculated according to the principle of the MMSE. After getting out the angle of the moire fringe we begin to calculate the width of moire fringe. A line vertical with the moire fringe is drawn and we can get the width of the moire fringe by the vertical line. In order to get over the influence of the noise an effective area with the shape of diamond is selected in the image. The data of area is accumulated and projected according to the direction of moire fringe and a sine curve come out. The width of moire fringe can be obtained by getting the position of the first wave crest the position of the last wave crest and the number of wave crest. Experiments prove that the precision of the method put forward in this paper is enhanced in comparison with the traditional frequency method the precision of width calculation achieves to 99.6% according to the evaluation indicators of width detection error. The computing speed is boosted largely compared with traditional method and it can achieve with 15 ms that satisfying the demand of real time. 2011 SPIE.

Error Bounds for Uniform Asymptotic Expansions-Modified Bessel Function of Purely Imaginary Order 期刊论文 OAI收割
CHINESE ANNALS OF MATHEMATICS SERIES B, 2010, 卷号: 31, 期号: 5, 页码: 759-780
作者: Shi, Wei; Wong, Roderick

收藏 | 浏览/下载：23/0 | 提交时间：2015/06/25

Modified Bessel function of purely imaginary order Airy function Uniform asymptotic expansion Error bound

Novel method for optimizing polishing tool-path in CCOS based on weighted-iterative algorithm (EI CONFERENCE) 会议论文 OAI收割
4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies, November 19, 2008 - November 21, 2008, Chengdu, China
作者: Zhang X.-J.; Wang X.; Wang X.; Wang X.; Wang X.-K.

收藏 | 浏览/下载：41/0 | 提交时间：2013/03/25

In Computer Controlled Optical Surfacing (CCOS) polishing tool-path is the base of solving other control parameters such as dwell time. In order to improve the fabrication results of polishing off-axis aspheric a novel method to optimize the tool-path is discussed in this paper. The optimizing method named weighted-iterative algorithm is according to the balance principle of the particle system. The power factor of each dwell point represents the requirement of dwell density. Considering the factors which influence the polishing result the power factors cosist of three elements include constant error distribution and dwell distance of workpiece edge. The tool-path is solved by numerical iterative method. In the end an error data is simulated with actual parameters using the matrix-based algorithm with two different tool-paths. The one is X-Y uniform spacing model and the other one is to optimize it based on the first. The comparison shows that the results of the optimized one are much better than traditional one especially the rms convergence rate. Theory of the algorithm is simple and exercisable and it satisfies practical requirement as well. 2009 SPIE.

The automatic photoresist coating machine on the spherical surface (EI CONFERENCE) 会议论文 OAI收割
2009 IEEE International Conference on Mechatronics and Automation, ICMA 2009, August 9, 2009 - August 12, 2009, Changchun, China
作者: Li Y.

收藏 | 浏览/下载：21/0 | 提交时间：2013/03/25

The photoresist coating is an important micro machining process widely applied in engineering. The formed film should be uniform and enough thin to assure the quality of final pattern whose line width is micrometer or nanometer. It is more difficult to process it on the spherical surface than on the flat. In this work mathematic model of film thickness on the spherical surface is proposed by using hydromechanics. The key factors that influence the film thickness are obtained from the analysis of coating process. Then the rational parameters which be controlled by the automatic photoresist coating machine can be final set up according to the result of the coating experiments. And the accuracy analysis of the key part which is used for the main process is performed by the error analytics. This machine not only makes the whole coating process automation but also monitors the film quality in real time. It is adequate for aspheric surface also. 2009 IEEE.

Automatic spin coater for concave spherical substrate (EI CONFERENCE) 会议论文 OAI收割
3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies, AOMATT 2007: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems, July 8, 2007 - July 12, 2007, Chengdu, China
Fengchao L.; Jingsong G.; Xiaoguo F.; Jingli Z.; Zhijun X.; Jun H.; Fenglin X.; Huiqing W.; Xiaohan L.

收藏 | 浏览/下载：23/0 | 提交时间：2013/03/25

Coating photoresist film with uniform thickness on concave spherical substrate (CSS) is very important for microfabrication of concave spherical optical elements by lithography technique via a laser direct writer for the uneven photoresist film will result in ununiformity of line width so as to influence the characters of optical elements. For improving the uniformity of photoresist film coating on CSS an automatic spin coater was designed. The process and the mathematical model of spin coating for CSS were analyzed. Difficulties for realizing the spin coater consist of the control of multi-axis motion precisely and collaboratively valves on/ff properly and real-timely. A flexible and well-behaved spinning motion system was achieved by tmeans of principal and subordinate CPUs control. The motion program for spin coating could be created and implemented automatically while the pressure and the valves were was watched and controlled in real time. Film coating and laser direct writing experiments on a CSS with aperture equals to 100 mm and radius equals to 370 mm were performed. Photoresist film with uniform thickness on CSS was obtained by selecting proper spin coating parameters such as rotational speed acceleration and viscosity of the photoresist. After development the section analysis by the atomic force microscope showed that photoresist film thickness was about 517 nm in the center and about 520 nm in the edge of substrate the film thickness error was within 1% and the line width was about 6.0 m with steep sides parallel each other. Experimental results indicate that uniform thickness of thin photoresist film has been coated on CSS by the spin coater which contributes to quality improvement of laser direct writing lines on CSS.