نتایج جستجو برای: fourier transform of time

تعداد نتایج: 21279094  

2011
Sedigheh Ghofrani

The fractional Fourier transform can be considered as a rotated standard Fourier transform in general and its benefit in signal processing is growing to be known more. Noise removing is one application that fractional Fourier transform can do well if the signal dilation is perfectly known. In this paper, we have computed the first and second order of moments of fractional Fourier transform acco...

Journal: :amirkabir international journal of modeling, identification, simulation & control 2014
s. s. nourazar a. mohammadzadeh m. nourazar

in the present work, a hybrid of fourier transform and homotopy perturbation method is developed for solving the non-homogeneous partial differential equations with variable coefficients. the fourier transform is employed with combination of homotopy perturbation method (hpm), the so called fourier transform homotopy perturbation method (fthpm) to solve the partial differential equations. the c...

Journal: :amirkabir international journal of modeling, identification, simulation & control 2015
s. s. nourazar h. tamim s. khalili a. mohammadzadeh

in this paper, we present a comparative study between the modified variational iteration method (mvim) and a hybrid of fourier transform and variational iteration method (ftvim). the study outlines the efficiencyand convergence of the two methods. the analysis is illustrated by investigating four singular partial differential equations with variable coefficients. the solution of singular partia...

2013
Yibing Li Yanhuan Wang Yun Lin

As the useful time-frequency tool, the Fractional Fourier Transform (FRFT) and the Short Time Fourier Transform (STFT) have a great development of signal recognition. And the Reduced Fractional Fourier Transform (RFRFT) was recently proposed and has been used in the recognition and estimation of chirp signals. A new method based on STFT and RFRFT is presented for radar signals modulation recogn...

2017
Benjamin Samson Michael Atlan

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau...

Journal: :journal of nanostructures 2013
h. abbasian d. ghanbari g. nabiyouni

cupric oxide nanostructures were synthesized via a simple reaction between copper nitrate and sodium hydroxide using a sonochemical-assisted method. the synthesized cuo was then characterized using x-ray diffraction, scanning electron microscopy, transmission electron microscopy, fourier transform infrared, ultraviolet-visible and photoluminescence spectroscopy. our studies show that the cuo na...

2016
Roland Badeau

In many signal processing applications, recent techniques often rely on the estimation of a probabilistic model. Many times, this model does not focus on the observed data itself, but rather on a spectral or time-frequency transform of this data, such as the discrete Fourier transform (DFT) or the short-time Fourier transform (STFT). A common statistical assumption regarding these transforms is...

Journal: :Int. J. Math. Mathematical Sciences 2006
Madan Lal Mittal B. E. Rhoades Vishnu Narayan Mishra

Mittal and Rhoades (1999–2001) andMittal et al. (2006) have initiated the studies of error estimates En( f ) through trigonometric Fourier approximations (TFA) for the situations in which the summability matrix T does not have monotone rows. In this paper, we determine the degree of approximation of a function ̃ f , conjugate to a periodic function f belonging to the weighted W(Lp,ξ(t))-class (p...

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

چکیده ندارد.

Journal: :journal of theoretical and applied vibration and acoustics 0
ali mokhtari department of mechanical engineering, isfahan university of technology, isfahan 84156-83111, iran vahid sarvestan department of mechanical engineering, isfahan university of technology, isfahan 84156-83111, iran hamid reza mirdamadi department of mechanical engineering, isfahan university of technology, isfahan 84156-83111, iran

in this article, vibration analysis of an euler-bernoulli beam resting on a pasternak-type foundation is studied. the governing equation is solved by using a spectral finite element model (sfem). the solution involves calculating wave and time responses of the beam. the fast fourier transform function is used for temporal discretization of the governing partial differential equation into a set ...

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