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浏览/检索结果: 共6条，第1-6条 帮助 限定条件 发表日期：2006     已选(0)清除 条数/页：5101520253035404550556065707580859095100   排序方式：请选择作者升序作者降序题名升序题名降序发表日期升序发表日期降序提交时间升序提交时间降序 An improved two-dimensional entropy method for star trail tracing in deep sky (EI CONFERENCE) 会议论文 ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China Yao Z.-J.; Wang Y.-J.; Han Q.-L. 收藏  |  浏览/下载：16/0  |  提交时间：2013/03/25 The trace of star trail is an important component of deep sky detection. The stars are low contrast targets  and their self-rotation will make their brightness change in cycle. Above all  the trail trace is vulnerable to the block and disturbance of other stars. Traditional one-dimensional maximum entropy thresholding algorithm is vulnerable to the noise  and the calculation of two-dimensional entropy methods is too large and takes too much time. This paper proposes an improved two-dimensional entropy threshold algorithm. We use recursion iteration method to eliminate the redundancy calculation  and reduce the size of two-dimensional histogram based on the deep sky stars characteristic  such as low contrast  fuzziness and the centralized histogram. We also combine our algorithm with the space trail trace model to forecast the star trace. Experiments results show  when the star are blocked or they turn dark  the method still can well extrapolate the star trace. Our method improves the capability of trailing the ebb and small star  and increases the precision of tracing. It is also robust to the noise  so there is a good application foreground for the method.   Research on tracking approach to low-flying weak small target near the sea (EI CONFERENCE) 会议论文 ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China Zhang S.-Y.; Liu W.-N.; Xue X.-C. 收藏  |  浏览/下载：25/0  |  提交时间：2013/03/25 Automatic target detection is very difficult in complicate background of sea and sky because of the clutter caused by waves and clouds nearby the sea-level line. In this paper  in view of the low-flying target near the sea is always above the sea-level line  we can first locate the sea-level line  and neglect the image data beneath the sea-level line. Thus the noise under the sea-level line can be suppressed  and the executive time of target segmentation is also much reduced. A new method is proposed  which first uses neighborhood averaging method to suppress background and enhance targets so as to increase SNR  and then uses the multi-point multi-layer vertical Sobel operator combined with linear least squares fitting to locate the sea-level line  lastly uses the centroid tracking algorithm to detect and track the target. In the experiment  high frame rate and high-resolution digital CCD camera and high performance DSP are applied. Experimental results show that this method can efficiently locate the sea-level line on various conditions of lower contrast  and eliminate the negative impact of the clutter caused by waves and clouds  and capture and track target real-timely and accurately.   Displacement estimation by the phase-shiftings of fourier transform in present white noise (EI CONFERENCE) 会议论文 ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China Wu Y.-H.; Yu Q.-Y. 收藏  |  浏览/下载：19/0  |  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.   Detection and tracking of low contrast targets based on integertype lifting wavelet transform (EI CONFERENCE) 会议论文 ICO20: Remote Sensing and Infrared Devices and Systems, August 21, 2005 - August 26, 2005, Changchun, China Wang L.; Shen X.; Wang Y. 收藏  |  浏览/下载：11/0  |  提交时间：2013/03/25 This paper presents a method for detecting and tracking of low contrast targets. The new method uses an integer-type lifting wavelet transform and the proposed method doesn't extract patterns similar to a template  but finds parts having the same feature in the targets. We utilize one of integer-type lifting wavelet transforms that contains rounding-off arithmetic for mapping integers to integers. The lifting term contains parameters that are learned by using standard training images of targets. We assume that the targets include many high frequency components. In order to obtain the features of the targets  the lifting parameters are determined by a condition that high frequency components are vanished in wavelet transform. But the condition cannot be determined by the parameters wholly. So  we put an additional condition of minimizing the squared sum of the lifting parameters. The advantage of using integer-type wavelet transform is simple and robust to noise. Simulation illustrated the approach can detect and track the moving targets in dim background. We would test our algorithm in the TV tracking system.   A 3.5-GHz low-noise amplifier for first-generation ultra-wideband radio 期刊论文 microwave and optical technology letters, 2006 Yang, L; Liao, HL; Zhang, GY; Huang, R; Zhang, X 收藏  |  浏览/下载：2/0  |  提交时间：2015/11/10 forward gain  low-noise amplifer (LNA)  noise figure (NF)  input matching  ultra-wideband (UWB)  SYSTEM   A novel fast lock-in phase-locked loop frequency synthesizer with direct frequency presetting circuit 期刊论文 japanese journal of applied physics part 1-regular papers brief communications & review papers, 2006, 卷号: 45, 期号: 4b, 页码: 3290-3294 Kuang XF; Wu NJ; Shou GL 收藏  |  浏览/下载：64/0  |  提交时间：2010/04/11 lock-in speed  direct frequency presetting  mixed-signal voltage-controlled oscillator (VCO)  phase-locked loop (PLL)  synthesizer  LOW-NOISE  CMOS