نتایج جستجو برای: Single-frequency section

تعداد نتایج: 1434664  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی خواجه نصیرالدین طوسی - دانشکده مهندسی برق و کامپیوتر 1391

power transformers are important equipments in power systems. thus there is a large number of researches devoted of power transformers. however, there is still a demand for future investigations, especially in the field of diagnosis of transformer failures. in order to fulfill the demand, the first part reports a study case in which four main types of failures on the active part are investigate...

Journal: :فیزیک زمین و فضا 0
احسان ذبیحی نائینی حمیدرضا سیاهکوهی

spectral decomposition is a powerful tool for analysis of seismic data. fourier transform determines the frequency contents of a signal. but for analysis of non-stationary signals, 1-d transform to frequency domain is not sufficient. in early years, transforming of seismic traces into time and frequency domain was done via windowed fourier transform, called a short time fourier transform (stft)...

ژورنال: فیزیک زمین و فضا 2018

Time-frequency filtering is an acceptable technique for attenuating noise in 2-D (time-space) and 3-D (time-space-space) reflection seismic data. The common approach for this purpose is transforming each seismic signal from 1-D time domain to a 2-D time-frequency domain and then denoising the signal by a designed filter and finally transforming back the filtered signal to original time domain. ...

Journal: :nursing practice today 0
elham shakibazadeh department of midwifery, school of nursing and midwifery, zanjan university of medical sciences, zanjan, iran. rana bayat department of midwifery, school of nursing and midwifery and student research committee, zanjan university of medical sciences, zanjan, iran. azam tahernejad department of midwifery, school of nursing and midwifery and student research committee, zanjan university of medical sciences, zanjan, iran. sonia sepehri department of midwifery, school of nursing and midwifery and student research committee, zanjan university of medical sciences, zanjan, iran.

background & aim : the causes of increased rate of cesarean section (c-section) are not completely known. the repeated c-sections are frequently reported in studies conducted in iran. this study aimed to determine the frequency of, and indications for the first time csection (fcs) in zanjan, iran in 2012-2013. methods & materials : a cross-sectional study was conducted and systematic random sam...

Journal: :فیزیک زمین و فضا 0
محمد رداد دانشجوی دکتری ژئوفیزیک، گروه فیزیک زمین، مؤسسة ژئوفیزیک دانشگاه تهران، ایران عبدالرحیم جواهریان استاد بازنشسته، گروه فیزیک زمین، مؤسسه ژئوفیزیک، دانشگاه تهران و استاد دانشکده مهندسی نفت دانشگاه صنعتی امیرکبیر، تهران، ایران

most geologic changes have a seismic response but sometimes this is expressed only in certain spectral ranges hidden within the broadband data. spectral decomposition is one of the methods which can be utilized to help interpreting such cases. there are several time-frequency methods including: short-time fourier transform (stft), continuous wavelet transform (cwt), wigner-ville distribution (w...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی اصفهان - دانشکده فیزیک 1390

in this thesis, barium ferrite nano particles were prepared by sol-gel method. their structural and magnetic properties of samples have been investigated using thermo gravimetric analysis (tg-dta), x-ray powder diffractometer (xrd), fourier transform infrared (ftir), scanning electron microscopy (sem), field emission scanning electron microscopy (fesem), ac susceptometer, vibrating sample magne...

پایان نامه :0 1374

chapter i provides an overview of structural linguistics and touches upon the saussurean dichotomies with the final goal of exploring their relevance to the stylistic studies of literature. to provide evidence for the singificance of the study, chapter ii deals with the controversial issue of linguistics and literature, and presents opposing views which, at the same time, have been central to t...

Journal: :iranian journal of health sciences 0
afshin fayyaz-movaghar department of statistics, school of mathematical sciences, university of mazandaran, babolsar, iran mohammad taghi kamel-mirmostafaee department of statistics, school of mathematical sciences, university of mazandaran, babolsar, iran tahura sadat borhani department of statistics, school of mathematical sciences, university of mazandaran, babolsar, iran

background and purpose: the identification of genetics risk factors of human diseases is very important. this study is conducted to model the allele frequencies (afs) of alzheimer’s disease. materials and methods: in this study, several candidate probability distributions are fitted on a data set of alzheimer’s disease genetic risk factor. unknown parameters of the considered distributions are ...

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