中国科学院机构知识库网格系统: 检索

Reentry guidance based on parametric optimization (EI CONFERENCE) 会议论文 OAI收割
2012 International Conference on Mechatronics and Control Engineering, ICMCE 2012, November 29, 2012 - November 30, 2012, Guangzhou, China
作者: Li D.

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This paper presents a parametric optimization approach to solve reentry guidance. Due to the various constraints imposed on the trajectory original guidance problem can be converted into an optimal control problem with a merit function to be minimized. Direct implementation of method of variation and is too complex to get a reasonable result while a numerical parametric optimization approach is feasible and efficient if we choose appropriate control variables as the optimization parameters and effective optimization algorithm. A simulation of the approach is performed to show its validity on reentry guidance problem: as the value of merit function converges to acceptable threshold all constraints are hold. (2013) Trans Tech Publications Switzerland.

Evaluation of the operating range for ground-based infrared imaging tracking 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 Z.-D.

收藏 | 浏览/下载：48/0 | 提交时间：2013/03/25

Ground-based infrared imaging tracking system (GIITS) is of great importance for aerial target warning and guard. The operating range is one of the key performance specifications on the other which should be calculated calculate the radiation power received on the detector in order to analysis whether the output signal meets the detection requirements or not analyzed and studied during the whole GIITS design process. The operating range is mostly influenced by a few factors without considering the effect of the background radiation. By improving of the traditional method including atmospheric attenuation a new operating range calculation model of the GIITS was established based on two requirements. One is that the image size of observed target should meet the requirement of the processor signal extraction. The number of the pixel occupied by target image should be more than 9. The other is that the signal noise ratio (SNR) of the GIITS should not be less than 5 to meet the requirements of the target detection probability and spatial frequency. The SNR calculation equation in form of energy is deduced and the radiation characteristic of the observed target and background are analyzed. When evaluate the operating range of the GIITS using the new method the performance of GIITS and feature of target and background. This paper firstly makes analysis and summarization on the definite localizations of the traditional operating range equation of the GIITS. The localizations are mainly in two aspects. On one hand we should successively calculate two operating range values according to two requirements mentioned above and choose the minimum value as the analytic result. In the end the dispersion of the image and the effect of image dispersion are not considered in the traditional method an evaluation of operating range for fighter aircraft is accomplished as an example. The influence factors in every aspect on operating range were explored by the calculated result. The new operating range calculation model provides the theoretical basis for the design and applications as well as the comprehensive evaluation of a GIITS. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Distribution of gyroscope accuracy parameters for E-O stabilization platform (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: Zhang X.; Zhang X.; Zhang X.; Jiang H.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

E-O stabilization platform performance is partly decided by gyroscope precision so it is important to choose a gyroscope with proper accuracy for an E-O stabilization platform. Based on the method of using a gyroscope in practice gyroscope error model is established. With the gyroscope error model gyroscope accuracy parameters that is bias repeatability bias stability scale factor scale factor nonlinearity output noise and bandwidth are separately analyzed. According to the concretely required performance indices for an E-O platform means of distribution of gyroscope accuracy parameters is proposed. A MEMS gyroscope is tested to get the parameters. Bias stability of the gyroscope is 0.08 /s while the bandwidth is 60 Hz. Output noise both at zero input and at nonzero input is analyzed by means of PSD to get the result that nonzero output noise is higher than zero output noise. Frequency response result of the gyroscope is dealt by means of correlation analysis. With all the tested result and the method of distribution of gyroscope accuracy parameters it is clear that how the gyroscope errors works in an E-O servo system. The principle of distribution of gyroscope accuracy parameters is helpful for choosing appropriate gyroscope for an E-O platform. 2011 IEEE.

Brazing RB-SiC used in large aperture space optical system (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Materials and Products Manufacturing Technology, ICMPMT 2011, October 28, 2011 - October 30, 2011, Chengdu, China
Zhang B.; Zhang Z.

收藏 | 浏览/下载：24/0 | 提交时间：2013/03/25

Because of the sic material's superior optical characteristic machine characteristic and hot characteristic it becomes currently the space big aperture reflector choose firstly1. For larger aperture sic mirror it is not economical and safe to make the monolithic body directly 2 3. The SiC mirror brazed assembly with several segments can solve these problems. In this paper one 600 mm sic plane mirror as demonstration welded with 3 radial segments is roughly grinded to the required figure at first then the mirror is finely grinded and polished by the technology of CCOS the mirror figure error is less than 1/20 ( = 632.8nm) in RMS finally. The problems of the preferential removal near braze joint are solved. The methods of reducing the residual stress of mirror are discussed. At last some measurements and experiments are carried on and the results conclude that the brazed SiC mirror can meet the requirement of large aperture optical systems. (2011) Trans Tech Publications.

The application of TMS320c64x DSP assembly language in correlation tracking algorithms (EI CONFERENCE) 会议论文 OAI收割
2010 3rd International Congress on Image and Signal Processing, CISP 2010, October 16, 2010 - October 18, 2010, Yantai, China
Huang D.; Wu Z.; Liang M.; Dong Y.; Peng T.

收藏 | 浏览/下载：20/0 | 提交时间：2013/03/25

In order to improve the real-time performance of the conventional correlation tracking algorithm based on full search method for its huge computation amount and vast correlation matching times in the process of searching an optimal matching position a method of combining the TMS320C64x DSP assembly language and software pipelining is proposed to realize template matching which costs the most time of the algorithm. Choose high performance DSP chip TMS320DM642 as the core processor of the hardware platform and schedule each one of the instruction in the algorithm to maximize performance using the instruction-level parallelism of the DSP. The experimental results indicate the time of template image matching implemented in assembly language has decreased from 49.36ms to 0.62ms. It is concluded that the correlation tracking adopting proposed method can meet the real-time and stability requirement of the target tracking. 2010 IEEE.

A new image fusion algorithm based on wavelet transform (EI CONFERENCE) 会议论文 OAI收割
2010 3rd International Conference on Advanced Computer Theory and Engineering, ICACTE 2010, August 20, 2010 - August 22, 2010, Chengdu, China
作者: He X.; Zhang Y.; Zhang L.-G.; Zhang L.-G.

收藏 | 浏览/下载：13/0 | 提交时间：2013/03/25

A new image fusion algorithm based on lifting wavelet transform is presented in this paper. The source images are decomposed using lifting wavelet transform respectively. Aiming at the coefficients of low frequency and high frequency this algorithm choose a different rule to fuse the image. To the low frequency the spatial frequency based on the neighborhood add consistency check is elected as the fusion guide. And the absolute maximum based on detail coefficients is selected as the guide to the high frequency. After that the fused image is obtained by using inverse lifting wavelet transform. Taking the ratio space frequency error and the mean gradient as criterions experimental results demonstrate that the algorithm is very effective. 2010 IEEE.

Real-time motive vehicle detection with adaptive background updating model and HSV colour space (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
Rong-Hui Z.; Bai Y.; Hong-guang J.; Chen T.

收藏 | 浏览/下载：68/0 | 提交时间：2013/03/25

In the transportation monitor system we set up the area of interest (AOI) of the vehicle model and adjust the size of AOI dynamically in order to track vehicle accurately. The results of experiment show that motive vehicle detection by adopting digital image is one of key technologies. To detect motive vehicle accurately the arithmetic proposed in the paper can suppress shadow availably we establish an adaptive background updating model firstly. Noise is suppressed by using modality filter detect motive vehicle accurately and satisfy real-time motive vehicle tracking. 2009 SPIE. and we obtain binary image by using maximum entropy to choose dynamic adaptive threshold. Based on positive information of shadow and aspect feature of motive vehicle we adopt HSV colour space and double threshold to solve the problem of vehicle shadow. According to prediction result of Kalman filtering

An object recognition method based on fuzzy theory and BP networks (EI CONFERENCE) 会议论文 OAI收割
ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China
Chuan W.; Ming Z.; Dong Y.

收藏 | 浏览/下载：20/0 | 提交时间：2013/03/25

It is difficult to choose eigenvectors when neural network recognizes object. It is possible that the different object eigenvectors is similar or the same object eigenvectors is different under scaling shifting rotation if eigenvectors can not be chosen appropriately. In order to solve this problem the image is edged the membership function is reconstructed and a new threshold segmentation method based on fuzzy theory is proposed to get the binary image. Moment invariant of binary image is extracted and normalized. Some time moment invariant is too small to calculate effectively so logarithm of moment invariant is taken as input eigenvectors of BP network. The experimental results demonstrate that the proposed approach could recognize the object effectively correctly and quickly.

High-accuracy real-time automatic thresholding for centroid tracker (EI CONFERENCE) 会议论文 OAI收割
ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China
作者: Wang Y.; Wang Y.; Wang Y.; Wang Y.; Zhang Y.

收藏 | 浏览/下载：37/0 | 提交时间：2013/03/25

Many of the video image trackers today use the centroid as the tracking point. In engineering we can get several key pairs of peaks which can include the target and the background around it and use the method of Otsu to get intensity thresholds from them. According to the thresholds it give a great help for us to get a glancing size a target's centroid is computed from a binary image to reduce the processing time. Hence thresholding of gray level image to binary image is a decisive step in centroid tracking. How to choose the feat thresholds in clutter is still an intractability problem unsolved today. This paper introduces a high-accuracy real-time automatic thresholding method for centroid tracker. It works well for variety types of target tracking in clutter. The core of this method is to get the entire information contained in the histogram we can gain the binary image and get the centroid from it. To track the target so that we can compare the size of the object in the current frame with the former. If the change is little such as the number of the peaks the paper also suggests subjoining an eyeshot-window we consider the object has been tracked well. Otherwise their height just like our eyes focus on a target if the change is bigger than usual position and other properties in the histogram. Combine with this histogram analysis we will not miss it unless it is out of our eyeshot we should analyze the inflection in the histogram to find out what happened to the object. In general the impression will help us to extract the target in clutter and track it and we will wait its emergence since it has been covered. To obtain the impression what we have to do is turning the analysis into codes for the tracker to determine a feat threshold. The paper will show the steps in detail. The paper also discusses the hardware architecture which can meet the speed requirement. the paper offers a idea comes from the method of Snakes

Adaptive Image Segmentation based on Fast Thresholding and Image Merging (EI CONFERENCE) 会议论文 OAI收割
16th International Conference on Artificial Reality and Telexistence - Workshops, ICAT 2006, November 29, 2006 - December 1, 2006, Hangzhou, China
作者: Zhang Y.; Wang Y.; Wang Y.; Wang Y.; Wang Y.

收藏 | 浏览/下载：14/0 | 提交时间：2013/03/25

Image segmentation is the first essential and important step of low level vision. This paper proposes a novel algorithm for adaptive image segmentation it can be applied in many conditions based on thresholding technique and segments merging according to their characteristics combine with spatial position. Our earlier work of getting the entire information of the histogram could help choose the multiple thresholds. However including complex target segmented. We describe the algorithm in detail and perform simulation experiments. The computation based on pixels can fully parallel processing to save time. 2006 IEEE. not all the peaks of the histogram correspond to obvious structural unit in the image. Spatial information must be involved. This paper also suggests subjoining segments matching for video image tracking. They will give great help to image segmentation. The proposed algorithm can meet the real-time requirement and lead to higher segmentation accuracy some types of texture can also be segmented well