نتایج جستجو برای: wavelet transform and s

تعداد نتایج: 16932503  

Rahman Kabiri Seyed Vahab Shojaedini,

Introduction In recent years methods based on radio frequency waves have been used for detecting breast cancer. Using theses waves leads to better results in early detection of breast cancer comparing with conventional mammography which has been used during several years. Materials and Methods In this paper, a new method is introduced for detection of backscattered signals which are received by...

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...

2009
Yanwei Wang Jeff Orchard

In this paper, we investigate the use of the Stockwell Transform for image compression. The proposed technique uses the Discrete Orthogonal Stockwell Transform (DOST), an orthogonal version of the Discrete Stockwell Transform (DST). These mathematical transforms provide a multiresolution spatial-frequency representation of a signal or image. First, we give a brief introduction for the Stockwell...

Journal: :ژورنال بین المللی پژوهش عملیاتی 0
n. mousazadeh abbasi m. a. aghaei m. moradzadeh fard

the goal of this research is to predict total stock market index of tehran stock exchange, using the compound method of arima and neural network in order for the active participations of finance market as well as macro decision makers to be able to predict trend of the market. first, the series of price index was decomposed by wavelet transform, then the smooth's series  predicted by using...

Journal: :فیزیک زمین و فضا 0
naeim mousavi ph.d. candidate, institute of geophysics, university of tehran, tehran, iran vahid ebrahimzadeh ardestani professor, institute of geophysics, university of tehran, tehran, iran

the s-transform has widely been used in the analysis of non-stationary time series. a simple method to obtain depth estimates of gravity field sources is introduced in this study. we have developed a new method based on the spectral characteristics of downward continuation to estimate depth of structures. this calculation procedure is based on replacement of the fourier transform with the s-tra...

Journal: :IEEE Trans. Signal Processing 1996
Robert Glenn Stockwell Lalu Mansinha R. P. Lowe

The S transform, which is introduced in this correspondence, is an extension of the ideas of the continuous wavelet transform (CWT), and is based on a moving and scalable localizing Gaussian window. It is shown here to have some desirable characteristics that are absent in the continuous wavelet transform. The S transform is unique in that it provides frequency-dependent resolution while mainta...

A. Ahmadian A. Mostafa M. Gitie M. J. Abolhasani

Introduction: A major problem facing the patients with chronic liver diseases is the diagnostic procedure.  The conventional diagnostic method depends mainly on needle biopsy which is an invasive method. There  are  some  approaches  to  develop  a  reliable  noninvasive  method  of  evaluating  histological  changes  in  sonograms. The main characteristic used to distinguish between the normal...

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...

N. Aghazadeh Y. Gholizade Atani

In this paper, we present an edge detection method based on wavelet transform and Hessian matrix of image at each pixel. Many methods which based on wavelet transform, use wavelet transform to approximate the gradient of image and detect edges by searching the modulus maximum of gradient vectors. In our scheme, we use wavelet transform to approximate Hessian matrix of image at each pixel, too. ...

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