中国科学院机构知识库网格系统: 检索

On hyperspectral remotely sensed image classification based on MNF and AdaBoosting (EI CONFERENCE) 会议论文 OAI收割
2012 3rd IEEE/IET International Conference on Audio, Language and Image Processing, ICALIP 2012, July 16, 2012 - July 18, 2012, Shanghai, China
作者: Yu P.; Yu P.; Gao X.

收藏 | 浏览/下载：23/0 | 提交时间：2013/03/25

As an effective statistical learning tool AdaBoosting has been widely used in the field of pattern recognition. In this paper a new method is proposed to improve the classification performance of hyperspectral images by combining the minimum noise fraction (MNF) and AdaBoosting. Because the hyperspectral imagery has many bands which have strong correlation and high redundancy the hyperspectral data are pre-processed by the minimum noise fraction to reduce the data's dimensionality whilst to remove noise bands simultaneously. Then we use an AdaBoost algorithm to conduct the classification of hyperspectral remotely sensed image. Experimental results show that the classification accuracy is improved and the time of calculation is reduced as well. 2012 IEEE.

An improved hyperspectral classification algorithm based on back-propagation neural networks (EI CONFERENCE) 会议论文 OAI收割
2012 2nd International Conference on Remote Sensing, Environment and Transportation Engineering, RSETE 2012, June 1, 2012 - June 3, 2012, Nanjing, China
作者: Yu P.; Yu P.

收藏 | 浏览/下载：31/0 | 提交时间：2013/03/25

In this paper a new method is proposed to improve the classification performance of hyperspectral images by combining the principal component analysis (PCA) genetic algorithm (GA) and artificial neural networks (ANNs). First some characteristics of the hyperspectral remotely sensed data such as high correlation high redundancy etc. are investigated. Based on the above analysis we propose to use the principal component analysis to capture the main information existing in the hyperspectral images and reduce its dimensionality consequently. Next we use neural networks to classify the reduced hyperspectral data. Since the back-propagation neural network we used is easy to suffer from the local minimum problem we adopt a genetic algorithm to optimize the BP network's weights and the threshold. Experimental results show that the classification accuracy is improved and the time of calculation is reduced as well. 2012 IEEE.

Study on spectrograph for ionosphere: A broadband imaging instrument prototype for far-ultraviolet (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Space Exploration Technologies and Applications, May 24, 2011 - May 26, 2011, Beijing, China
作者: Wang S.-R.; Lin G.-Y.; Yu L.

收藏 | 浏览/下载：35/0 | 提交时间：2013/03/25

Current research on space-based exploration for the ionosphere needs more advanced technologies. Because the spectral signals in the ionosphere distributing basically in the far-ultraviolet waveband are very weak. Usual spectrometer structures and detectors such as CCD can't receive enough information. Based on this principle of atmospheric sounding the imaging spectrometer prototype for ionosphere detection application was designed to solve the problem. This prototype consists of the telescope and the imaging spectrometer. The simple structure and small number of mirrors can help higher transmission efficiency be achieved and weak signals detection be implemented. The telescope is an off-axis parabolic mirror and the spectrometer is a modified Czerny-Turner spectral imaging system. Modified Czerny-Turner spectrometer contains a spherical mirror a fixed plane grating and a toroidal mirror. By adjusting the incident angle to the collimating mirror and using toroidal mirror coma and astigmatism were corrected well. We also optimize distances between the grating to the focusing mirror and the focusing mirror to the image plane to improve disadvantages of traditional Czerny-Turner structure. Designed results demonstrate that aberrations are substantially corrected and high image quality can be obtained in broad waveband. The photon counting Wedge-Strip-Anode detector with micro-channel planes as the receiving plane is accepted for the instrument prototype. The other photon counting 2-D detector responding well for weak light such as Cross-Delay line detector and MAMA detector can also be used for detection. The calibration and performances testing system is made of a vacuum system a deuterium lamp a monochrometer and the instrument prototype. Results obtained from the experiment show that the spectral resolution is 2.4 nm and the spatial resolution is 80 m. The other calibration experiments are running. The technology of the spectrometer prototype is important for the research and applications of ionosphere remote sensing. 2011 SPIE.

Observations and analysis of extreme ultraviolet emission between 10nm and 70nm by capillary discharge with Xe as target (EI CONFERENCE) 会议论文 OAI收割
2011 Academic International Symposium on Optoelectronics and Microelectronics Technology, AISOMT 2011, October 12, 2011 - October 16, 2011, Harbin, China
作者: Yang L.; Yang L.

收藏 | 浏览/下载：17/0 | 提交时间：2013/03/25

Spectra have been recorded from a Xe discharge capillary discharge source in the extreme ultraviolet (EUV) region between 10nm and 70nm. The origin of the spectra have been analyzed which have shown that the spectra between 10nm and 20nm come from the transitions of 4p-4d 4d-4f and 4d-5p by Xe 7+Xe12+ and the spectra between 20nm70nm mainly from the transitions of Xe6+Xe8+ as well. The results which have been integrated the experimental results with the theory have shown that the spectra from Xe6+Xe8+ formed in the time after the collapsed of the compressing of the plasma. 2011 IEEE.

High accuracy star image locating and imaging calibration for star sensor technology (EI CONFERENCE) 会议论文 OAI收割
6th International Symposium on Precision Engineering Measurements and Instrumentation, August 8, 2010 - August 11, 2010, Hangzhou, China
作者: Wang Y.; Wang Y.; Wang Y.; Wang Y.; Wang Y.

收藏 | 浏览/下载：21/0 | 提交时间：2013/03/25

Today aircraft attitude measurement technology plays an important role in an aircraft system because it can provide orientation for aircraft in action. Lately star sensor technology used in aircraft attitude measurement has become more and more popular because of its high accuracy light weight without attitude accumulation errors and other advantages. There are three main steps for star sensor to measure aircraft attitude star image locating star identification and attitude tracking. The latter two steps are based on the accuracy of star image locating. So it's critical to make efforts to advance the accuracy of star image locating. Some imaging errors such as spherical aberration or coma aberration also have negative effect on the accuracy of star image locating of which the effect is necessarily reduced as well. At the beginning of this article the structure of star sensor hardware is introduced. Secondly three methods for star image locating are described specifically which are traditional centroid method Gauss quadric fitting method and improved Gauss quadric fitting method. Subsequently an imaging calibration method is described for the purpose of reducing the effect of imaging errors. Finally the experiment shows that the accuracy of the star sensor is 2-arc-second. 2010 SPIE.

The registration of aerial infrared and visible images (EI CONFERENCE) 会议论文 OAI收割
2010 International Conference on Educational and Information Technology, ICEIT 2010, September 17, 2010 - September 19, 2010, Chongqing, China
作者: Liu J.; Wang Y.; Wang Y.; Wang Y.; Wang Y.

收藏 | 浏览/下载：23/0 | 提交时间：2013/03/25

In order to solve the registration problem of different source image existed on aerial image fusion algorithms based on Particle Swarm Optimization (PSO) are applied as search strategy in this paper and Alignment Metric (AM) is used as judgment. This study has realized the different source image registration of infrared and visible light with high speed high accuracy and high reliability. Basically with little restriction of gray level properties a new alignment measure is applied which can efficiently measure the image registration extent and tolerate noise well. Even more the intelligent optimization algorithm - Particle Swarm Optimization (PSO) is combined to improve the registration precision and rate of infrared and visible light. Experimental results indicate that the study attains the registration accuracy of pixel level and every registration time is cut down over 40 percent compared to traditional method. The match algorithm based on AM solves the registration problem that greater differences between different source images are existed on gray and characteristic. At the same time the adoption of combining the intelligent optimization algorithms significantly improves the searching efficiency and convergence speed of the algorithms and the registration result has higher accuracy and stability which builds up solid foundation for different source image fusion. The method in this paper has a magnificent effect and is easy for application and very suitable for engineering use. 2010 IEEE.

Analysis of inertia dyadic uncertainty for small agile satellite with control moment gyros (EI CONFERENCE) 会议论文 OAI收割
2010 IEEE International Conference on Mechatronics and Automation, ICMA 2010, August 4, 2010 - August 7, 2010, Xi'an, China
作者: Zhang L.; Zhang L.; Sun Z.

收藏 | 浏览/下载：19/0 | 提交时间：2013/03/25

With the increasing demands for the agility of the next earth imaging satellite control moment gyro (CMG) is considered to be the most suitable actuator because of its torque amplification capability. However a CMG system may introduce uncertainty of inertia dyadic to a satellite's attitude control system. The uncertainty is negligible for large space vehicles but it has not been tested whether it can be ignored for small agile satellites. How to model the CMG system inertia dyadic varying with gimbal angles and what influence it will put on the performance of attitude control system haven't been test accurately as well. All of them are dealt with mathematically and accurately in this paper. This paper firstly gives mathematic descriptions of the inertia dyadic of the 4-CMG pyramid configuration system varying with gimbal angles and then designs a variable structure control law for small agile satellite using CMGs. Finally numerical simulation suggests that the inertia dyadic variation of a 4-CMG pyramid configuration system is approximately centesimal of the total inertia dyadic of the satellite and that the designed variable structure control law is of good robust performance for an example of large-angle attitude maneuver despite of the variation of the inertia dyadic. 2010 IEEE.

Semi-physical simulation of an optoelectronic tracking servo system based on C MEX S functions (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
Juan C.; Junhong Z.

收藏 | 浏览/下载：26/0 | 提交时间：2013/03/25

To the design of an optoelectronic tracking servo system we test the method [1 not only the reasonability of the control algorithm should be considered 2]. The simulation results verify the theoretical analysis. Because C MEX S function has the features of fast execute speed but the cost and time as well. It is necessary to establish the simulation model for the system. Applying the C MEX S functions independently generated program we can build the every independent digital control modules in MATLAB/SIMULINK for the optoelectronic tracking servo system. In the paper directly download to the hardwires we apply the C MEX S function to the design of the practical optoelectronic tracking servo system. For the speed we can design and debug the digital control modules in MATLAB/SIMULINK and then transform and download directly to DSP processor. 2010 IEEE. position loop control and TV delay compensations

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：39/0 | 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.

Correction method for detection of the frequencies of railway fsk signals (EI CONFERENCE) 会议论文 OAI收割
2008 9th International Conference on Signal Processing, ICSP 2008, October 26, 2008 - October 29, 2008, Beijing, China
作者: Yu J.

收藏 | 浏览/下载：63/0 | 提交时间：2013/03/25

In order to acquire the information of railway binary frequency-shift keying signals which include upper/down side frequencies and base low-frequency with high-accuracy a novel frequency detection algorithm for France UM-71 system is proposed. Combining fast Fourier transform with the ratio correction method the carrier frequency and the base frequency are obtained. Furthermore the hardware consumption has been decreased. And it possesses the advantage of simple algorithm and fast operation speed. Comparing with the detection of the base frequency the upper/down side frequency of railway signal is more difficult. Based on spectrum analysis and the spectrum correction a new method which adopts the sliding window is put forward in this paper. The absolute differences between the upper side frequencies and the down side frequencies obtained are regarded as the criterion for judgment. Then the set of data in which the maximum absolute value is is to be the result of the upper/down side frequency. Because the sliding window will go through every stage when the upper/down side frequency changes therefore it is not sensitive enough to the position of data which need to be transformed. Using the method mentioned above the experiment results show that the accuracy requirement of the side frequency is satisfied well. 2008 IEEE.