中国科学院机构知识库网格系统: 检索

Electron mobility in the linear region of an AlGaN/AlN/GaN heterostructure field-effect transistor 期刊论文 OAI收割
CHINESE PHYSICS B, 2013, 卷号: 22, 期号: 6
Yu, YX; Lin, ZJ; Luan, CB; Wang, YT; Chen, H; Wang, ZG

收藏 | 浏览/下载：42/0 | 提交时间：2014/01/16

AlGaN/AlN/GaN heterostructure field-effect transistors quasi-two-dimensional model the polarization Coulomb field scattering the two-dimensional electron gas mobility

Characteristic point match algorithm based on the SURF in binocular stereo vision (EI CONFERENCE) 会议论文 OAI收割
5th International Conference on Intelligent Networks and Intelligent Systems, ICINIS 2012, November 1, 2012 - November 3, 2012, Tianjin, China
作者: Wang L.; Wang L.; Wang L.; Yang L.; Yang L.

收藏 | 浏览/下载：33/0 | 提交时间：2013/03/25

One of the main components of the computer vision is 3D reconstruction. Extracts and the match based on two-dimensional picture characteristic point is the 3D reconstruction technology core. Taking binocular stereoscopic vision theory as a foundation through extracts the characteristics of SURF based on the multi-scale analysis this feature has specific scale reproducibility put the epipolar constraints and disparity constraints as conditions judgement to specific screening it is greatly reduced the search range. The experiment use the matching method for three different actual scenes the results shows that the method can enhance the image matching speed and precision and can get more precise dense parallax used for reconstruction complete scene. 2012 IEEE.

Modelling of the electric field assisted capillarity effect used for the fabrication of hollow polymer microstructures (EI CONFERENCE) 会议论文 OAI收割
2012 13th International Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2012, April 16, 2012 - April 18, 2012, Cascais, Portugal
Tonry C.; Patel M.; Bailey C.; Desmuliez M. P. Y.; Cargill S.; Yu W.

收藏 | 浏览/下载：101/0 | 提交时间：2013/03/25

Electric Field Assisted Capillarity (EFAC) is a novel process which has the potential for the single step fabrication of hollow polymer microstructures. The process has been shown to work experimentally on a microscale level using Polydimethylsiloxane (PDMS). The process makes use of both the electrohydrodynamics of polymer at a microscale and the voltage enhanced capillary force exerted on the polymer. This paper discusses the results of a two-dimensional numerical simulation of this process. The results presented use a patterned master electrode producing encapsulated microchannels in the polymer. The simulations demonstrate how the differing contact angles between the polymer and the walls of the master electrode affect the thickness of the top surface of the formed microstructures. It also specifies the conditions necessary for the successful fabrication of such microstructures. 2012 IEEE.

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：74/0 | 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.

The investigation of point defect modes of phononic crystal for high Q resonance (EI CONFERENCE) 会议论文 OAI收割
2011 16th International Solid-State Sensors, Actuators and Microsystems Conference, TRANSDUCERS'11, June 5, 2011 - June 9, 2011, Beijing, China
作者: Liu J.; Liu J.; Liu J.; Li F.

收藏 | 浏览/下载：23/0 | 提交时间：2013/03/25

Point defect cavity was constructed in a two-dimensional phononic crystal plate. It was excited by a small piezo chip in the cavity and the vibration of each point defect modes were detected by an optical interferometer. Point defect modes on 2D PC plate in vacuum air and loaded with water were investigated theoretically and experimentally to make clear of Q factors which are affected by inner attenuation band gap effects and medium. The way to get high Q resonance has been found. It helps to design a new kind of resonator or sensor. 2011 IEEE.

The angular velocity estimation principal of -- filter based on high sampling rate (EI CONFERENCE) 会议论文 OAI收割
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011, July 15, 2011 - July 17, 2011, Inner Mongolia, China
作者: Zhang Y.

收藏 | 浏览/下载：36/0 | 提交时间：2013/03/25

In order to get angular velocity of stabilization servo mechanism from angular position sensors -- filter and its angular velocity transfer function were predigested. Combing with optimum parameters -- filter based on high sampling rate was established the effect of and sample rate on filter nature frequency were evaluated. According to the requirements of stabilization platform the principle of steady and transient tracking filter differential were proved. With the hypothesis of constant acceleration the frequency characteristics of angular velocity transfer function were analyzed three-dimensional Kalman filter was simplified and the filter parameters were designed. The results show that when the spectrum of input signal was lower than 6rad/s parameters was 0.02 and sampling period were 0.08ms and 0.1ms respectively the filter can realize differential exactly when the spectrum was 9rad/s the precision was no less than 1.1% the phase leading of angular position was no less than 70 the natural frequency should be higher than the cut-off frequency of stabilization platform was two or three times. In the engineering of electro-optical stabilization servo mechanism -- filter has properties of tracking differential and reached the requirement of platform angular velocity estimation. Also it is one of the effective methods to get angular velocity from angular position sensors. 2011 IEEE.

Roughness analysis of optical surfaces by X-ray scattering (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electronics and Optoelectronics, ICEOE 2011, July 29, 2011 - July 31, 2011, Dalian, China
作者: Chen B.; Chen B.

收藏 | 浏览/下载：34/0 | 提交时间：2013/03/25

A grazing incidence x-ray scattering (XRS) method Order perturbation theory (FOPT) is stated briefly and an experimental facility based on an improved X-ray diffraction has been introduced which can work with high performance. The x-ray scattering distributions of two super smooth silicon samples measured at the incidence angle 0.2 degree as the x-ray wavelength is 0.154 nm have been given and analyzed by the FOPT to give information about the surface profiles. As a comparison the root mean square (RMS) surface roughness grey-scale maps and one-dimensional power spectral density (1D PSD) have been derived from the atomic-force microscope (AFM) data. The results evaluated by FOPT are in good agreement with that of AFM which indicates that x-ray scattering method is a practical characterization for the investigation of super smooth surfaces. 2011 IEEE.

Image compression based on contourlet and no lists SPIHT (EI CONFERENCE) 会议论文 OAI收割
2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering, CMCE 2010, August 24, 2010 - August 26, 2010, Changchun, China
作者: Zhang S.

收藏 | 浏览/下载：56/0 | 提交时间：2013/03/25

The volume of raw image data captured by the high resolution camera is extremely huge. Thus the efficient image compression method should be used to decrease the bit rate. The image compression method based on wavelet is used more widely nowadays. However two dimensional wavelet is only the tensor product of the one dimensional wavelet whose support region of basis function is extended from interval to square. Contourlet is an image multiscale geometric analysis tool which could represent image sparsely and has strong capability of nonlinear approximation. The basis function of contourlet is multidirectional and anisotropic. Nevertheless contourlet is redundant. So the non-redundant Wavelet Based Contourlet Transform (WBCT) is used in this paper. The SPIHT algorithm is very efficient way to coding the significant coefficients. And the improved no lists SPIHT is more easy to implemented by hardware. Image compression method based on the combination of both wavelet based contourlet transform and no lists SPIHT coding is proposed in the paper. Experiment shows that compared to wavelet based scheme the contourlet scheme can reserve the texture of the image. For barbara test image when coding at low bit rate the PSNR can improve about 0.2dB. 2010 IEEE.

Parallel estimation of translation for video stabilization (EI CONFERENCE) 会议论文 OAI收割
2010 6th International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2010, September 23, 2010 - September 25, 2010, Chengdu, China
作者: Wang H.; Liu G.; Wang H.; Wang H.; Wang H.

收藏 | 浏览/下载：103/0 | 提交时间：2013/03/25

Translation motion estimation is the major aspect of video motion compensation especially in two-dimensional turntable. This paper presents a robust parallel estimation algorithm of translation in video stabilization system. The equivalent model of translation that derived is accorded with small rotation angle comparatively. A parallel algorithm based on grey mapping is used in local motion estimation to shorten the estimation time and improve the computation efficiency. After local motion vectors are calculated a fast filter can detect the spurious vectors avoiding possible jerks. The suggested translation estimation algorithm has been implemented on NVIDIA GTX 260 the experimental results show that the average time of the estimation and compensation finished in 16 ms/frame and stabilize 1k1k pixels sequence gray video up to 60 frames/s. 2010 IEEE.

Motion mechanism analysis of a two-degree-of-freedom spherical motor (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Information Engineering and Computer Science, ICIECS 2010, December 25, 2010 - December 26, 2010, Wuhan, China
作者: Guo K.

收藏 | 浏览/下载：24/0 | 提交时间：2013/03/25

The working principle of a two-degree-of-freedom piezoelectric spherical motor using only one piezoelectric element was analyzed. The resonance frequencies of the motor's plate type piezoelectric vibrator were calculated by finite element method. The computer simulation was executed to analyze the motion trajectory of the four contact points between the stator and the sphere. Simulation results verified that the four contact points can form timing reasonable elliptical trajectories which re designed to drive the sphere to form two rotation degrees of freedom. The conclusion indicated the formation of two-dimensional movement mechanism of the spherical motor. 2010 IEEE.