نتایج جستجو برای: quasi wavelet

تعداد نتایج: 121585  

Journal: :Journal of applied physiology 2006
Bruce J West Artur Maciejewski Miroslaw Latka Tadeusz Sebzda Zbigniew Swierczynski Sylwia Cybulska-Okolow Eugeniusz Baran

We present a novel approach to the analysis of fluctuations in human myoelectrical gastric activity measured noninvasively from the surface of the abdomen. The time intervals between successive maxima of the wavelet transformed quasi-periodic electrogastrographic waveform define the gastric rate variability (GRV) time series. By using the method of average wavelet coefficients, the statistical ...

Journal: :فیزیک زمین و فضا 0
امین روشندل کاهو دانشجوی دکتری ژئوفیزیک، گروه فیزیک زمین، مؤسسة ژئوفیزیک دانشگاه تهران، ایران حمیدرضا سیاهکوهی دانشیار، گروه فیزیک زمین، مؤسسة ژئوفیزیک، دانشگاه تهران، ایران

based on the convolutional model, a seismic trace is the convolution of seismic source wavelet and reflection coefficient series of the earth. seismic source wavelet estimation is one of the most important stages in processing and interpretation of seismic data. accurate estimation of wavelet increases the efficiency of the deconvolution and temporal resolution of seismic data. on the other han...

2014
Markus Weimar

This paper is concerned with problems in the context of the theoretical foundation of adaptive (wavelet) algorithms for the numerical treatment of operator equations. It is well-known that the analysis of such schemes naturally leads to function spaces of Besov type. But, especially when dealing with equations on non-smooth manifolds, the definition of these spaces is not straightforward. Never...

Journal: :فیزیک زمین و فضا 0
امین روشندل کاهو فرشاد سلاجقه

introduction: wavelet transform is one of the useful and suitable tools for time series and signal analysis. nowadays wavelet transform is frequently used in geophysical data processing and interpretation, especially seismic data. however, the use of this method isn’t widespread in gravity and geomagnetic. fedi and quarta (1998), martelet et al. (2001) and de oliveira lyrio (2004) used the wave...

Journal: :فیزیک زمین و فضا 0
عبدالرضا صفری دانشیار، گروه مهندسی نقشه برداری، پردیس دانشکده های فنی دانشگاه تهران، ایران محمدعلی شریفی استادیار، گروه مهندسی نقشه برداری، پردیس دانشکده های فنی دانشگاه تهران، ایران اسماعیل فروغی دانشجوی کارشناسی ارشد ژئودزی، گروه مهندسی نقشه برداری، پردیس دانشکده های فنی دانشگاه تهران، ایران هادی امین دانشجوی کارشناسی ارشد ژئودزی، گروه مهندسی نقشه برداری، پردیس دانشکده های فنی دانشگاه تهران، ایران

one of the most important problems in geodesy is the unification of height datum. generally in geodesy; there are two types of height systems, the geometrical height based on ellipsoid and the physical height based on gravity-defined surface (zhang et al, 2009).local height datum is determined according to mean sea level (msl). in regarding to mismatch of mean sea level and geoid, on the one ha...

Journal: :مرتع و آبخیزداری 0
پریوش طوفانی کارشناس ارشد مهندسی منابع آب دانشگاه علوم کشاورزی و منابع طبیعی گرگان احمد فاخری فرد استاد، گروه مهندسی آب دانشگاه تبریز ابوالفضل مساعدی استاد دانشکدة منابع طبیعی و محیط زیست دانشگاه فردوسی مشهد امیر احمد دهقانی دانشیار گروه مهندسی آب دانشگاه علوم کشاورزی و منابع طبیعی گرگان

prediction of precipitation is very important. regarding to the non- linear relationships and uncertainty of models, there is no superior and persuasive model among various proposed models to simulate precise precipitation and its amount. wavelet is one of the novel and very effective methods in time series and signals analyzing, that has been considered in the field of hydrology in recent year...

Journal: :Earth, Planets and Space 2022

Abstract The responses of two High-Intensity Long-Duration Continuous AE Activity (HILDCAA) events are investigated using solar wind observations at L1, magnetospheric measurements geosynchronous orbit, and changes in the global ionosphere. This study provides evidence existence quasi-periodic oscillations (1.5–2 h) ionospheric electric field over low latitudes, total electron content high magn...

Removing noise from images is a challenging problem in digital image processing. This paper presents an image denoising method based on a maximum a posteriori (MAP) density function estimator, which is implemented in the wavelet domain because of its energy compaction property. The performance of the MAP estimator depends on the proposed model for noise-free wavelet coefficients. Thus in the wa...

Journal: :wavelet and linear algebra 2015
a. ghaani farashahi

finite affine groups are given by groups of translations and di-lations on finite cyclic groups. for cyclic groups of prime orderwe develop a time-scale (wavelet) analysis and show that for alarge class of non-zero window signals/vectors, the generatedfull cyclic wavelet system constitutes a frame whose canonicaldual is a cyclic wavelet frame.

Baniamerian, Z.,

This paper concentrates on a new procedure which experimentally recognises gears and bearings faults of a typical gearbox system using a least square support vector machine (LSSVM). Two wavelet selection criteria Maximum Energy to Shannon Entropy ratio and Maximum Relative Wavelet Energy are used and compared to select an appropriate wavelet for feature extraction. The fault diagnosis method co...

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