نتایج جستجو برای: fourier transform spectrum

تعداد نتایج: 354752  

2010
Ori Katz Jonathan M. Levitt Yaron Silberberg

We describe an approach based on compressive-sampling which allows for a considerable reduction in the acquisition time in Fourier-transform spectroscopy. In this approach, an N-point Fourier spectrum is resolved from much less than N time-domain measurements using a compressive-sensing reconstruction algorithm. We demonstrate the technique by resolving sparse vibrational spectra using <25% of ...

2004
Shigeki Sagayama Keigo Takahashi Hirokazu Kameoka Takuya Nishimoto

In this paper, we propose a new signal processing technique, “specmurt anasylis,” that provides piano-rolllike visual display of multi-tone signals (e.g., polyphonic music). Specmurt is defined as inverse Fourier transform of linear spectrum with logarithmic frequency, unlike familiar cepstrum defined as inverse Fourier transform of logarithmic spectrum with linear frequency. We apply this tech...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه ولی عصر (عج) - رفسنجان - دانشکده علوم 1387

چکیده ندارد.

2003
G. BOFFETTA

The cubic nonlinear Schroedinger equation (NLS) describes the space-time evolution of narrow-banded wave trains in one space and one time (1 + 1) dimensions. The richness of nonlinear wave motions described by NLS is exemplified by the fully nonlinear envelope soliton and “breather” solutions, which are fully understood only in terms of the general solution of the equation as described by the i...

2004
Shigeki Sagayama Keigo Takahashi Hirokazu Kameoka Takuya Nishimoto

In this paper, we propose a new signal processing technique, “specmurt anasylis,” that provides piano-rolllike visual display of multi-tone signals (e.g., polyphonic music). Specmurt is defined as inverse Fourier transform of linear spectrum with logarithmic frequency, unlike familiar cepstrum defined as inverse Fourier transform of logarithmic spectrum with linear frequency. We apply to music ...

2003
Z. Leonowicz T. Lobos J. Rezmer

Time-varying spectra of non-stationary time-series commonly used are spectrograms from the Short-Time Fourier Transform (STFT). The most prominent limitation of the Fourier Transform is that of frequency resolution. To overcome the limitation the Wavelet Transform, Wigner-Ville Distribution and the Min-Norm subspace method have been applied for spectrum estimation of non-stationary signals caus...

Journal: :Stroke 1994
L Bunegin D Wahl M S Albin

BACKGROUND AND PURPOSE Cerebral embolism has been implicated in the development of cognitive and neurological deficits following bypass surgery. This study proposes methodology for estimating cerebral air embolus volume using transcranial Doppler sonography. METHODS Transcranial Doppler audio signals of air bubbles in the middle cerebral artery obtained from in vivo experiments were subjected...

Journal: :international journal of robotics 0
hamid d. taghirad k.n. toosi university of technology hamid d. taghirad k.n. toosi university of technology fateme bakhshande k.n. toosi university of technology

visual servoing is generally contained of control and feature tracking. study of previous methods shows that no attempt has been made to optimize these two parts together. in kernel based visual servoing method, the main objective is to combine and optimize these two parts together and to make an entire control loop. this main target is accomplished by using lyapanov theory. a lyapanov candidat...

Journal: :iranian journal of medical physics 0
bahareh shalchian ph.d. student, medical physics dept., faculty of medical sciences, tarbiat modares university, tehran, iran hossein rajabi associate professor, medical physics dept., faculty of medical sciences, tarbiat modares university, tehran, iran hamid soltanian-zadeh professor, control and intelligent processing center of excellence, electrical and computer engineering dept., university of tehran, tehran, iran

introduction: an efficient method of tomographic imaging in nuclear medicine is positron emission tomography (pet). compared to spect, pet has the advantages of higher levels of sensitivity, spatial resolution and more accurate quantification. however, high noise levels in the image limit its diagnostic utility. noise removal in nuclear medicine is traditionally based on fourier decomposition o...

Journal: :journal of mining and environment 2012
mostafa javid behzad tokhmechi

there are two methods for identifying formation interface in oil wells: core analysis, which is a precise approach but costly and time consuming, and well logs analysis, which petrophysists perform, which is subjective and not completely reliable. in this paper, a novel coupled method was proposed to detect the formation interfaces using gr logs. second approximation level (a2) of gr log gained...

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