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浏览/检索结果: 共5条，第1-5条 帮助 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 PQR signal quality indexes: A method for real-time photoplethysmogram signal quality estimation based on noise interferences 期刊论文 BIOMEDICAL SIGNAL PROCESSING AND CONTROL, 2019, 卷号: 47, 页码: 88-95 作者:  Song, Jiajia[1];  Li, Dan[2];  Ma, Xiaoyuan[3];  Teng, Guowei[4];  Wei, Jianming[5] 收藏  |  浏览/下载：10/0  |  提交时间：2019/04/22 Photoplethysmograph  Signal quality estimation  High-frequency noises  Baseline wandering  Motion artifacts   A quasi-maximum likelihood approach for integrated covariance matrix estimation with high frequency data 期刊论文 JOURNAL OF ECONOMETRICS, 2014, 卷号: 180, 期号: 2 作者:  Liu, Cheng;  Tang, Cheng Yong 收藏  |  浏览/下载：1/0  |  提交时间：2019/12/05 High frequency data  Integrated covariance matrix  Microstructure noises  Quasi-maximum likelihood   Design and image restoration research of a cubic-phase-plate system (EI CONFERENCE) 会议论文 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies, April 26, 2010 - April 29, 2010, Dalian, China Zhang X.; Zhang X.; Shi G.; Zhang J.; He F. 收藏  |  浏览/下载：18/0  |  提交时间：2013/03/25 Wave-front coding technology is a novel jointly optical and digital imaging technology which can greatly extend the depth of focus of optical systems. The image restoration process is an important part of wave-front coding technology. Using wave-front coding makes the modulation transfer function(MTF) values of the optical systems change little over a range of several times the depth of focus  which means the system MTF is quite insensitive to defocus  and there is no zero in the passband. So we can design a single filter for the restoration of images in different defocus positions. However  it's hard to avoid noise during image acquisition and transmission processes. These noises will be amplified in the image restoration  especially in the high frequency part when the MTF drop is relatively low. The restoration process significantly reduces the system signal to noise ratio this way. Aimed at the problem of noise amplification  a new algorithm was proposed which incorporated wavelet denoising into the iterative steps of Lucy-Richardson algorithm. Better restoration results were obtained through the new algorithm  effectively solving the noise amplification problem of original LR algorithm. Two sets of identical triplet imaging systems were designed  in one of which the cubic-phase-plate was added. Imaging experiments of the manufactured systems were carried  and the images of a traditional system and a wave-front coded system before and after decoding were compared. The results show that the designed wave-front coded system can extend the depth of focus by 40 times compared with the traditional system while maintaining the light flux and the image plane resolution. 2010 Copyright SPIE - The International Society for Optical Engineering.   Chip design of linear CCD drive pulse generator and control interface (EI CONFERENCE) 会议论文 2nd International Symposium on Advanced Optical Manufacturing and Testing Technologies - Advanced Optical Manufacturing and Testing Technologies, November 2, 2005 - November 5, 2005, Xian, China Cai R.; Sun H.; Wang Y. 收藏  |  浏览/下载：18/0  |  提交时间：2013/03/25 CCD noises and their causes are analyzed. Methods to control these noises  such as Correlated Double Sampling (CDS)  filtering  cooling  clamping  and calibration are proposed. To improve CCD sensor's performances  the IC  called Analog Front End (AFE)  integration of CDS  clamping  Programmable Gain Amplifier (PGA)  offset  and ADC  which can fulfill the CDS and analog-to-digital conversion  is employed to process the output signal of CCD. Based on the noise control approaches  the idea of chip design of linear CCD drive pulse generator and control interface is introduced. The chip designed is playing the role of (1) drive pulse generator  for both CCD and AFE  and (2) interface  helping to analysis and transfer control command and status information between MCU controller and drive pulse generator  or between global control unit in the chip and CCD/AFE. There are 6 function blocks in the chip designed  such as clock generator for CCD and AFE  MCU interface  AFE serial interface  output interface  CCD antiblooming parameter register and global control logic unit. These functions are implemented in a CPLD chip  Xilinx XC2C256-6-VQ100  with 20MHz pixel frequency  and 16-bit high resolution. This chip with the AFE can eliminate CCD noise largely and improve the SNR of CCD camera. At last  the design result is presented.   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：17/0  |  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.