نتایج جستجو برای: wavelet

تعداد نتایج: 38198  

Power transformers are the most important components of a power system, so their protection is a critical issue. This paper proposes a novel and efficient algorithm based on the high-frequency components of the differential current signal to discriminate between the magnetizing inrush currents and the internal faults. After detecting the over-current in the differential current signals, samples...

Journal: :iranian journal of medical physics 0
ali rastjoo ardakani msc in medical engineering, medical physics and medical engineering dept., faculty of medicine, tehran university of medical sciences, tehran, iran hossein arabalibeik assistant professor, medical physics and medical engineering dept., faculty of medicine, tehran university of medical sciences, tehran, iran

introduction: evoked potentials arisen by stimulating the brain can be utilized as a communication tool  between humans and machines. most brain-computer interface (bci) systems use the p300 component,  which is an evoked potential. in this paper, we evaluate the use of the hidden markov model (hmm) for  detection of p300.  materials and methods: the wavelet transforms, wavelet-enhanced indepen...

Journal: :فیزیک زمین و فضا 0
علی غلامی مؤسسه ژئوفیزیک دانشگاه تهران، دانشجوی دکتری حمیدرضا سیاهکوهی مؤسسه ژئوفیزیک دانشگاه تهران- استادیار

generally, the presence of noise in geophysical measurements is inevitable and depending on the type and the level it affects the results of geophysical studies. so, denoising is an important part of the processing of geophysical data. on the other hand, geophysicists make inferences about the physical properties of the earth interior based on the indirect measurements (data) collected at or ne...

Abazar Solgi, Behdad Falamarzi Heidar Zarei

Precipitation forecasting due to its random nature in space and time always faced with many problems and this uncertainty reduces the validity of the forecasting model. Nowadays nonlinear networks as intelligent systems to predict such complex phenomena are widely used. One of the methods that have been considered in recent years in the fields of hydrology is use of wavelet transform as a moder...

Journal: :wavelet and linear algebra 2014
k. nouri n. bahrami siavashani

fractional calculus has been used to model physical and engineering processes that are found to be best described by fractional differential equations. therefore, a reliable and efficient technique as a solution is regarded.this paper develops approximate solutions for boundary value problems ofdifferential equations with non-integer order by using the shannon waveletbases. wavelet bases have d...

E. Hajizade H. Ghiasi H. Rajabi S.R. Zakavi Sh. Olumi

Introduction: One of the major problems in the development of nuclear medicine images is the presence of noise. The noise level in nuclear medicine images is usually reduced by the analysis of imaging data in a Fourier transform environment. The main drawback of this environment belongs to low signal to noise ratio in high frequencies because removing noise frequencies may remove data and times...

A Javanbakht A.H Ghorbanpour Arani M Karimi, N Haghshenas

In this investigation a suitable algorithm for the detection of cracks in the pressure vessels is presented. The equations of motion for the vessel are obtained and transferred into the wavelet space in a simplified form resulted from time and position approximations. The locations of cracks are randomly distributed in different regions of the structure to cover the whole geometry of the pressu...

Can we characterize the wavelets through linear transformation? the answer for this question is certainly YES. In this paper we have characterized the Haar wavelet matrix by their linear transformation and proved some theorems on properties of Haar wavelet matrix such as Trace, eigenvalue and eigenvector and diagonalization of a matrix.

A. Salimi Shamloo, B. Parsa Moghaddam N. khorrami,

In this paper, interval Legendre wavelet method is investigated to approximated the solution of the interval Volterra-Fredholm-Hammerstein integral equation. The shifted interval Legendre polynomials are introduced and based on interval Legendre wavelet method is defined. The existence and uniqueness theorem for the interval Volterra-Fredholm-Hammerstein integral equations is proved. Some examp...

Journal: :iranian journal of medical physics 0
sh. olumi m.sc. in medical physics, tarbiat modarres university, tehran, iran h. rajabi assistant professor, medical physics dept., tarbiat modarres university, tehran, iran s.r. zakavi associate professor, nuclear medicine dept., imam reza hospital, mashhad university of medical sciences, mashhad, iran e. hajizade associate professor, biostatistics dept., tarbiat modarres university, tehran, iran h. ghiasi m.sc. in medical physics, torfe hospital, tarbiat modarres university, tehran, iran

introduction: one of the major problems in the development of nuclear medicine images is the presence of noise. the noise level in nuclear medicine images is usually reduced by the analysis of imaging data in a fourier transform environment. the main drawback of this environment belongs to low signal to noise ratio in high frequencies because removing noise frequencies may remove data and times...

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