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Study on an improved five-interferogram phase-shifting algorithm 被引量:2
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作者 罗志勇 代佳林 《Chinese Optics Letters》 SCIE EI CAS CSCD 2008年第5期342-345,共4页
Using traditional five-interferogram algorithm to unwrap phase for length measurement, the phase steps must be equal to π/2 exactly, but it is almost impossible to achieve in nanometer positioning technique. Aiming t... Using traditional five-interferogram algorithm to unwrap phase for length measurement, the phase steps must be equal to π/2 exactly, but it is almost impossible to achieve in nanometer positioning technique. Aiming to overcome this defect of traditional five-interferogram algorithm, an improved five-interferogram algorithm is presented. This improved algorithm not only keeps the high accuracy of traditional fiveinterferogram algorithm, but also does not need absolute equal step to unwrap phase. Instead, this algorithm only needs measuring phase-shifting. With the numerical simulation, the improved five-interferogram algorithm shows high accuracy, high reliability, and feasibility in practice. It is very valuable for accurate length measurement with Fizeau interferometer and Fabry-Perot interferometer. 展开更多
关键词 study on an improved five-interferogram phase-shifting algorithm than length Figure
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Study on a synthetic-aperture acoustic imagingfocusing algorithm in time-domain 被引量:2
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作者 SUN Baoshen ZHANG Fan and SHEN Jianzhong(Institute of Acoustics, Academia Sinica Beijing 100080) 《Chinese Journal of Acoustics》 1997年第4期322-331,共10页
A focusing algorithm in the time-domain is reported in this paper fbr synthetic-aperture acoustic imaging of wide band-width, and also is given the simulated imaging of a group of separated scattering point with PC co... A focusing algorithm in the time-domain is reported in this paper fbr synthetic-aperture acoustic imaging of wide band-width, and also is given the simulated imaging of a group of separated scattering point with PC computer. The parameters chosen in the computation are in accordance with our experimental system setup. 展开更多
关键词 time II MHz study on a synthetic-aperture acoustic imagingfocusing algorithm in time-domain
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Study of low bit rate speech codec algorithm in underwater acoustic communication 被引量:4
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作者 XIAO Dong MO Fuyuan +2 位作者 CHEN Geng GUO Shengming MA Li 《Chinese Journal of Acoustics》 2013年第4期411-424,共14页
At medium or long distance (〉 10 kin) underwater acoustic speech communication, information transfer rate is constrained by the complicated, time varying channel and limited bandwidth. The bit rate of speech coding... At medium or long distance (〉 10 kin) underwater acoustic speech communication, information transfer rate is constrained by the complicated, time varying channel and limited bandwidth. The bit rate of speech coding is required to be as low as possible. The time delay of underwater acoustic wave propagation can be used for low bit rate speech coding. After investigating the Mixed Excitation Linear Prediction (MELP) standard and taking account of the auditory perceptual features, a variable and adjustable bit rate speech codec algorithm has been proposed, whose average bit rate is about 600 bps. The average Perceptual Evaluation of Speech Quality Mean Opinion Score (PESQ MOS) of synthesized speeches is about 2.8. It has been proved by the computer simulation and sea trial that the performance of the proposed algorithm is well and robust when bit error rate is no more than 10-3. The synthesized speech is vivid and intelligible, and keeps main individual characteristics of speaker. 展开更多
关键词 MELP study of low bit rate speech codec algorithm in underwater acoustic communication RATE
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Sample size re-estimation without un-blinding for time-to-event outcomes in oncology clinical trials 被引量:1
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作者 Lihong Huang Jianling Bai +1 位作者 Hao Yu Feng Chen 《The Journal of Biomedical Research》 CAS CSCD 2018年第1期23-29,共7页
Sample size re-estimation is essential in oncology studies. However, the use of blinded sample size reassessment for survival data has been rarely reported. Based on the density function of the exponential distributio... Sample size re-estimation is essential in oncology studies. However, the use of blinded sample size reassessment for survival data has been rarely reported. Based on the density function of the exponential distribution, an expectation-maximization(EM) algorithm of the hazard ratio was derived, and several simulation studies were used to verify its applications. The method had obvious variation in the hazard ratio estimates and overestimation for the relatively small hazard ratios. Our studies showed that the stability of the EM estimation results directly correlated with the sample size, the convergence of the EM algorithm was impacted by the initial values, and a balanced design produced the best estimates. No reliable blinded sample size re-estimation inference can be made in our studies, but the results provide useful information to steer the practitioners in this field from repeating the same endeavor. 展开更多
关键词 oncology study clinical trial sample size re-estimation expectation-maximization algorithm
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AN OVERALL STUDY OF CONVERGENCE CONDITIONS FOR ALGORITHMS IN NONLINEAR PROGRAMMING
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作者 胡晓东 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 1993年第2期97-103,共7页
Since the point-to-set maps were introduced by Zangwill in the study of conceptual algorithms, various sufficient conditions for the algorithms to be of global convergence have been established.In this paper, the rela... Since the point-to-set maps were introduced by Zangwill in the study of conceptual algorithms, various sufficient conditions for the algorithms to be of global convergence have been established.In this paper, the relations among all these conditions are illustrated by a unified approach;still more, unlike the sufficient conditions previously given in the literature,a new necessary condition is put forward at the end of the paper, so that it implies more applications. 展开更多
关键词 AN OVERALL study OF CONVERGENCE CONDITIONS FOR algorithmS IN NONLINEAR PROGRAMMING
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