oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
A Comparative Study of Audio Compression Based on Compressed Sensing and Sparse Fast Fourier Transform (SFFT): Performance and Challenges  [PDF]
Hossam M. Kasem,Maha El-Sabrouty
Mathematics , 2014,
Abstract: Audio compression has become one of the basic multimedia technologies. Choosing an efficient compression scheme that is capable of preserving the signal quality while providing a high compression ratio is desirable in the different standards worldwide. In this paper we study the application of two highly acclaimed sparse signal processing algorithms, namely, Compressed Sensing (CS) and Sparse Fart Fourier transform, to audio compression. In addition, we present a Sparse Fast Fourier transform (SFFT)-based framework to compress audio signal. This scheme embeds the K-largest frequencies indices as part of the transmitted signal and thus saves in the bandwidth required for transmission
The Study on Particle Image Velocimetry Based on SOM Network
自组织映射神经网络在粒子图像匹配中的研究

LI Mu-guo,DU Hai,
李木国
,杜海

中国图象图形学报 , 2008,
Abstract: In order to reduce matching error,in this paper,a new matching method for particle images is proposed based on the SOM neural network,which combines the nearest-neighbor matching algorithm with the cross-correlation algorithm.Firstly,the cross-correlation approach is used to evaluate the initial matching position.Secondly,the processing results of the correlation are used to build the neural network.Thirdly,nearest-neighbor matching algorithm is adopted to select the best matching points.The modified method can reduce the number of false vectors and improve the practical value.At last,the synthetic particle images and real particle images are tested and the errors are analyzed.The experimental results show that the proposed method is a robust algorithm for measuring the movement of particles and the vector fields can be obtained with high precision.
Study on reconstruction of seismic data based on nonuniform Fourier transform
基于非均匀Fourier变换的地震数据重建方法研究

GAO Jian-jun,CHEN Xiao-hong,LI Jing-ye,LIU Zhi-peng,ZHANG Nan-nan,
高建军
,陈小宏,李景叶,刘志鹏,张南南

地球物理学进展 , 2009,
Abstract: The uneven seismic data impose serious impact on multi-trace processing algorithms, leading to suboptimal processing and imaging results. Reconstruction of uneven seismic data can be considered as a geophysical inverse problem. In this paper, a new reconstruction method based on non-uniform Fourier transform and Bayesian parameter estimation theory is proposed. The main idea of the method is calculating the band width depending on the minimum apparent velocity for each temporal frequency and estimating the Fourier spectrum from the uneven seismic data. Regarding to this inverse problem, it is solved by the conjugate gradient method for the stable solution and quick convergence. Examples on synthetic as well as on field data show that the proposed method is efficient and applicable.
Study on the inside source hologram reconstruction algorithm based on discrete Fourier transform
基于离散Fourier变换的内源全息图重构计算方法

Wang Jun-Yue,Zhu Pei-Ping,Zheng Xin,Yuan Qing-Xi,Tian Yu-Lian,Huang Wan-Xia,Wu Zi-Yu,
王寯越
,朱佩平,郑 欣,袁清习,田玉莲,黄万霞,吴自玉

物理学报 , 2005,
Abstract: The inside source hologram reconstruction algorithm based on discrete Fourier transform was investigated in detail, and how to calculate the contribution of whole spherical hologram to the reconstructed image of atoms was demonstrated in this algorithm, which was previously regarded to be capable of calculating only half of the spherical hologram. Using the sampling theorem in this issue, we are able to examine such essential factors as the sampling rate of the hologram, domain and resolution of reconstructed image.
Study on the Fourier Transform Demodulation Theory of the Spectropolarimeter Based on Intensity Modulation
强度调制偏振光谱仪傅里叶变换解调原理研究

SONG Zhi-ping,HONG Jin,QIAO Yan-li,QIU Zhen-wei,YE Song,CHENG Li-gang,WANG Yuan-jun,
宋志平
,洪津,乔延利,裘桢炜,叶松,陈立刚,汪元钧

光子学报 , 2008,
Abstract: The feasibility study is accomplished using the Fourier Transform (FT) method to demodulate the spectropolarimetric information for the new spectropolarimeter based on intensity modulation. The whole progress of mathematics derivation about it is proposed by analysing the modulation principle in the new spectropolarimeter. The simulation experiment on the demodulation progress is also achieved. The experimental results show that the high fidelity spectropolarimetric information from the targets can be demodulated when the FT method is used and it is an ideal and feasible method.
Optical Velocimetry  [PDF]
W. T. Buttler,S. K. Lamoreaux,F. G. Omenetto,J. R. Torgerson
Physics , 2004,
Abstract: This work considers current potential uses of laser Doppler velocimetry. A discussion of other optical velocimetry techniques is presented and compared with their practical application to modern shock physics diagnostics, such as VISAR.
Comparison of the Hemodynamic Effects of the Induction Agents Ketamine, Etomidate and Sevoflurane Using the Model of Electrical Velocimetry Based Cardiac Output Monitoring in Pediatric Cardiac Surgical Patients  [PDF]
Suruchi Hasija, Sandeep Chauhan, Neeti Makhija, Sarvesh Pal Singh, Sanjay Kumar, Arin Choudhury, Sachin Talwar, Usha Kiran
World Journal of Cardiovascular Surgery (WJCS) , 2014, DOI: 10.4236/wjcs.2014.410024
Abstract: Objective: To compare the haemodynamic effects of the induction agents ketamine, etomidate and sevoflurane using the model of electrical velocimetry based cardiac output monitoring in paediatric cardiac surgical patients. Design: Prospective randomized study. Setting: Tertiary care hospital. Participants: 60 children < 2 years age undergoing cardiac surgery. Interventions: The patients were randomized into 3 equal groups to receive 1.5-2.5 mg/kg iv ketamine (group K), 0.2-0.3 mg/kg iv etomidate (group E) or upto 8% sevoflurane (group S) as the induction agent. Hemodynamic parameters were noted before and after induction of anaesthesia utilizing a noninvasive cardiac monitor based on the model of electrical velocimetry. Measurements and Main Results: The demographic characteristics of the patients were similar in the three groups. The HR decreased in all groups, least in group E (P ≤ 0.01) but the MAP decreased only in group S (P ≤ 0.001). In group S, the stroke volume improved from 9 ± 3.2 ml to 10 ± 3.2 ml (P ≤ 0.05) and the stroke volume variation decreased from 25% ± 6.4% to 13% ± 6.2% (P ≤ 0.001). The stroke index and systemic arterial saturation improved in all groups (P ≤ 0.01). The cardiac index and index of contractility were unchanged. The transthoracic fluid content reduced in groups E and S, but did not change in group K (P ≤ 0.05). Conclusions: Etomidate appeared to provide the most stable conditions for induction of anesthesia in children undergoing cardiac surgery, followed by ketamine and sevoflurane.
Improving Raman velocimetry of laser-cooled cesium atoms by spin-polarization  [PDF]
Julien Chabé,Hans Lignier,Pascal Szriftgiser,Jean Claude Garreau
Physics , 2006, DOI: 10.1016/j.optcom.2007.02.008
Abstract: We study the peformances of Raman velocimetry applied to laser-cooled, spin-polarized, cesium atoms. Atoms are optically pumped into the F=4, m=0 ground-state Zeeman sublevel, which is insensitive to magnetic perturbations. High resolution Raman stimulated spectroscopy is shown to produce Fourier-limited lines, allowing, in realistic experimental conditions, atomic velocity selection to one-fiftieth of a recoil velocity.
Response of Retinal Blood Flow to Systemic Hyperoxia as Measured with Dual-Beam Bidirectional Doppler Fourier-Domain Optical Coherence Tomography  [PDF]
René M. Werkmeister, Stefan Palkovits, Reinhard Told, Martin Gr?schl, Rainer A. Leitgeb, Gerhard Garh?fer, Leopold Schmetterer
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045876
Abstract: Purpose There is a long-standing interest in the study of retinal blood flow in humans. In the recent years techniques have been established to measure retinal perfusion based on optical coherence tomography (OCT). In the present study we used a technique called dual-beam bidirectional Doppler Fourier-domain optical coherence tomography (FD-OCT) to characterize the effects of 100% oxygen breathing on retinal blood flow. These data were compared to data obtained with a laser Doppler velocimeter (LDV). Methods 10 healthy subjects were studied on 2 study days. On one study day the effect of 100% oxygen breathing on retinal blood velocities was studied using dual-beam bidirectional Doppler FD-OCT. On the second study day the effect of 100% oxygen breathing on retinal blood velocities was assessed by laser Doppler velocimetry (LDV). Retinal vessel diameters were measured on both study days using a commercially available Dynamic Vessel Analyzer. Retinal blood flow was calculated based on retinal vessel diameters and red blood cell velocity. Results As expected, breathing of pure oxygen induced a pronounced reduction in retinal vessel diameters, retinal blood velocities and retinal blood flow on both study days (p<0.001). Blood velocity data correlated well between the two methods applied under both baseline as well as under hyperoxic conditions (r = 0.98 and r = 0.75, respectively). Data as obtained with OCT were, however, slightly higher. Conclusion A good correlation was found between red blood cell velocity as measured with dual-beam bidirectional Doppler FD-OCT and red blood cell velocity assessed by the laser Doppler method. Dual-beam bidirectional Doppler FD-OCT is a promising approach for studying retinal blood velocities in vivo.
Laser Doppler Velocimetry for Joint Measurements of Acoustic and Mean Flow Velocities : LMS-based Algorithm and CRB Calculation  [PDF]
Laurent Simon,Olivier Richoux,Anne Degroot,Louis Lionet
Physics , 2009, DOI: 10.1109/TIM.2008.917670
Abstract: This paper presents a least mean square (LMS) algorithm for the joint estimation of acoustic and mean flow velocities from laser doppler velocimetry (LDV) measurements. The usual algorithms used for measuring with LDV purely acoustic velocity or mean flow velocity may not be used when the acoustic field is disturbed by a mean flow component. The LMS-based algorithm allows accurate estimations of both acoustic and mean flow velocities. The Cram\'er-Rao bound (CRB) of the associated problem is determined. The variance of the estimators of both acoustic and mean flow velocities is also given. Simulation results of this algorithm are compared with the CRB and the comparison leads to validate this estimator.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.