中国科学院机构知识库网格系统: 检索

Spatial reconstructed local attention Res2Net with F0 subband for fake speech detection 期刊论文 OAI收割
NEURAL NETWORKS, 2024, 卷号: 175, 页码: 11
作者: Fan, Cunhang; Xue, Jun; Tao, Jianhua; Yi, Jiangyan; Wang, Chenglong

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收藏 | 浏览/下载：30/0 | 提交时间：2024/07/04

ASVspoof Fake speech detection Fundamental frequency Res2Net

Fundamental Frequency Detection of Underwater Acoustic Target Using DEMON Spectrum and CNN Network 会议论文 OAI收割
Harbin, China, November 27-28, 2020
作者: Lu JM(卢佳敏); Song SM(宋三明); Hu ZQ(胡志强); Li S(李硕)

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收藏 | 浏览/下载：17/0 | 提交时间：2020/12/18

Fundamental frequency detection CNN DEMON comb filter hydrophone array signal

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.

Study on ultra-light secondary baffle for coaxial two-mirror telescope (EI CONFERENCE) 会议论文 OAI收割
2012 9th IEEE International Conference on Mechatronics and Automation, ICMA 2012, August 5, 2012 - August 8, 2012, Chengdu, China
作者: Zhang L.; Zhang L.

收藏 | 浏览/下载：62/0 | 提交时间：2013/03/25

The coaxial two-mirror telescope consists of two mirrors facing each other. Classical two-mirror arrangements are Gregorian and Cassegrain. These systems are usually applied to space telescopes and often have optical baffles to prevent stray light from entering the focal plane. The optical baffles consist of concentric rings suspended between the secondary and the primary mirror. The secondary baffle for a large two-mirror optical system is designed and analyzed in this paper. According to mission of a telescope the structure should have high stiffness and high reliability and light weight. Compared with invar aluminum alloy and titanium alloy carbon fiber composite is currently the best material in terms of weight-to-strength ratio. It also has advantages of high temperature tolerance and low thermal expansion. So carbon fiber composite is chosen as material to meet requirements of the coaxial telescope. In this paper optimization method based on finite element analysis (FEA) is used for design the secondary baffle. Minimum weight of the baffle is chosen as an objective function. Thicknesses of former tube and vanes are chosen as variables. Analysis results show that the designed secondary baffle has maximum diameter of 180mm total length of 120mm and weighs 142g. And its fundamental frequency reaches 651Hz. Therefore the baffle has many advantages such as ultra-light weight high stiffness and dimensional stability etc. The optimization method and the baffle design can be helpful to other coaxial telescopes such as Cassegrain Gregorian and their subdivisions. 2012 IEEE.

Design and optimization of supporting structure for scanning mirror in aviation remote sensor (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electric Information and Control Engineering, ICEICE 2011, April 15, 2011 - April 17, 2011, Wuhan, China
作者: Yang H.

收藏 | 浏览/下载：30/0 | 提交时间：2013/03/25

An optical supporting structure is studied to improve its structure stiffness and reduce the rotate error to meet the requirement of aviation remote sensor. A formula to calculate fundamental frequency is proposed using Rayleigh-Ritz method and a method of is analyzed. By means of OPTISTRUCT software the maximum fundamental frequency is converted to object function the deformation under the gravity and the mass are assigned to state variable wall thicknesses of the structure are converted to design variables. The analysis and test results indicate that the fundamental frequency of designed optical supporting structure has been improved 37.2 Hz from 96.9 Hz which guarantee the reliability of the sweep mechanism and the rotate error is 4.89 which is satisfied for the rotate accuracy in plunge angle. The method of optimization has a certain instructional significance for the design of supporting structures in aviation remote sensor. 2011 IEEE.

Compensation of moire fringe sinusoidal deviation in photoelectrical encoder based on tunable filter (EI CONFERENCE) 会议论文 OAI收割
2011 Symposium on Photonics and Optoelectronics, SOPO 2011, May 16, 2011 - May 18, 2011, Wuhan, China
作者: Wang Y.; Wang Y.; Wang Y.; Wang Y.; Wang Y.

收藏 | 浏览/下载：30/0 | 提交时间：2013/03/25

In order to improve the precision of the absolute photoelectrical encoder a compensating method is put forward which restrains the harmonics in moire fringe signal. After analyzing the relationship between the subdividing error and the sinusoidal index a low-pass digital filter which can make the moire signal satisfy the need of 1024 subdivision is designed. Considering with the fundamental frequency varies with the rotating speed of encoder the tunable filter is adopted whose cutoff frequency is calculated according to the coarse information of the encoder. The simulating results show that the proposed method can improve the sinusoidal index especially at high rotating speed. At last the compensating algorithm is implemented in the terminal of satellite optical communication which needs high resolution. The experimental results show indicate that the developed method is feasible. 2011 IEEE.

Application of particulate reinforced aluminum matrix composite in airborne photoelectric turret (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electric Information and Control Engineering, ICEICE 2011, April 15, 2011 - April 17, 2011, Wuhan, China
作者: Wang P.

收藏 | 浏览/下载：24/0 | 提交时间：2013/03/25

In order to design and manufacture more excellent airborne photoelectric stable turret modulus of elasticity of 213 GPa and thermal expansion coefficient of 7.9106/K. The frame has decreased the maximum deformation by by 60% and increased the fundamental frequency by 65% as compared with those of aluminum alloy materials a new type of aeronautical material-particulate reinforced aluminum matrix composite (SiC/Al composite) is investigated. Several crucial technologies respectively as shown by finite element analysis results. Those are confirmed by vibration test furthermore. Therefore such as pressureless infiltration technology a significant lightening effect is achieved and the thermal control load is also reduced. The test result indicates that the stable accuracy of the system achieves 19.8rad and the optical-axis parallelism of pay load is 0.1mrad. The research applies the SiC/Al composites to airborne photoelectric platforms interface reaction controls and plate's welding are systematically studied. Then which makes a effective exploration for the new aeronautical material's application. 2011 IEEE. using SiC/Al composites the airborne photoelectric stable turret frame is successfully prepared in density of 2.94 g/ cm3

Research on station mode for attitude determination of multiple targets (EI CONFERENCE) 会议论文 OAI收割
2010 International Conference on Computational and Information Sciences, ICCIS2010, December 17, 2010 - December 19, 2010, Chengdu, Sichuan, China
作者: Zhao L.; Wang J.; Li M.

收藏 | 浏览/下载：38/0 | 提交时间：2013/03/25

A key problem of attitude determination system is how to locate CMOS cameras and deal with relations among them. In this paper several kinds of multi-CMOS station mode are introduced. Fundamental principles and classification of station mode directly affect on measurement parameters of system. No matter what mode is designed the ultimate goal is to extend Effective Viewing Field (EVF) increase capture ratio of objects and increase measurement precision. Station mode introduced in this paper is made of CMOS cameras because of low cost high speed frame frequency and low power consumption CMOS cameras were putted near from object tested. So sequences of image are legible which are convenient for analysis of three dimensional(3D) attitude. 2010 IEEE.

Tunable ultraviolet laser source from a frequency doubled alexandrite laser (EI CONFERENCE) 会议论文 OAI收割
Optoelectronic Materials and Devices II, November 2, 2007 - November 5, 2007, Wuhan, China
Shuhang L.; Jingjiao L.; Lijun W.

收藏 | 浏览/下载：27/0 | 提交时间：2013/03/25

A tunable ultraviolet laser source in the spectrum range of 0.36-0.388 m was obtained as second harmonics from a frequency doubled Alexandrite laser whose output covers the wave range over 0.72-0.78 m. A LBO crystal was used as frequency doubling crystal. The phase mateching angle in the wide spectrum range of the crystal was calculated and the crystal was cut in the way that the normal incidence at the center wavelength of the fundamental wave at the crystal. The output spectrum line was measured and the highest second harmonics conversion efficiency reached 1.2% from long pulse fundamental wave at the center wavelength.

Displacement estimation by the phase-shiftings of fourier transform in present white noise (EI CONFERENCE) 会议论文 OAI收割
ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China
作者: Wu Y.-H.

收藏 | 浏览/下载：29/0 | 提交时间：2013/03/25

Displacement estimation is a fundamental problem in Real-time video image processing. It can be typically approached by theories based on features in spatial domain. This paper presents an algorithm which improves the theory for estimating the moving object's displacement in spatial domain by its Fourier transform frequency spectrum. Because of the characters of Fourier transform the result is based on all the features in the image. Utilizing shift theorem of Fourier transform and auto-registration the algorithm employs the phase spectrum difference in polar coordinate of two frame images sequence with the moving target1 2. The method needn't transform frequency spectrum to spatial domain after calculation comparing with the traditional algorithm which has to search Direc peak and it reduces processing time. Since the technique proposed uses all the image information including all the white noise in the image especially and it's hard to overcome the aliasing from noises but the technique can be an effective way to analyze the result in little white noise by the different characters between high and low frequency bands. It can give the displacement of moving target within 1 pixel of accuracy. Experimental evidence of this performance is presented and the mathematical reasons behind these characteristics are explained in depth. It is proved that the algorithm is fast and simple and can be used in image tracking and video image processing.