نتایج جستجو برای: sometimes also called intrinsic attenuation

تعداد نتایج: 2737336  

Journal: :فیزیک زمین و فضا 0
محمد صادق پرکان دانشجوی کارشناسی ارشد مؤسسة ژئوفیزیک دانشگاه تهران حمیدرضا سیاه کوهی استاد، گروه فیزیک زمین، موسسه زئوفیزیک دانشگاه تهران، ایران علی غلامی دانشیر، گروه فیزیک زمین، موسسه ژئوفیزیک دانشگاه تهارن، ایران

in this paper some new applications of empirical mode decomposition (emd) and hilbert spectrum in seismic ground-roll attenuation, random noise attenuation and spectral decomposition are introduced. hilbert spectrum is a time-frequency representation for hilbert-huang transform which is obtained by combination of instantaneous frequency (if) concept and intrinsic mode function of empirical mode...

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

the main objective in sampling is to select a sample from a population in order to estimate some unknown population parameter, usually a total or a mean of some interesting variable. a simple way to take a sample of size n is to let all the possible samples have the same probability of being selected. this is called simple random sampling and then all units have the same probability of being ch...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه الزهراء - دانشکده علوم پایه 1394

for a given riemannian manifold (m,g),it is an interesting question to study the existence of a conformal diffemorphism (also called as a conformal transformation) f : m ! m such that the metric g? = fg has one of the following properties: (i)(m; g?) has constant scalar curvature. (ii)(m; g?) is an einstein manifold.

Journal: :فیزیک زمین و فضا 0
فائزه شیرمحمدی دانشجوی کارشناسی ارشد، گروه فیزیک زمین، موسسه ژئوفیزیک، دانشگاه تهران، ایران ظاهر حسین شمالی دانشیار، گروه فیزیک زمین، موسسه ژئوفیزیک، دانشگاه تهران، ایران مهرداد پاکزاد استادیار، گروه فیزیک زمین، موسسه ژئوفیزیک، دانشگاه تهران، ایران

in many seismological applications, the earth is considered as a perfectly elastic, homogeneous, and isotropic body. although this assumption is approximately valid, it is known that seismic waves pass through the real earth that is anelastic, inhomogeneous and anisotropic.  we consider four processes that can reduce wave amplitude, i.e.: geometrical spreading, scattering, multi-pathing, and an...

Stress waves contain useful information about the properties of porous materials; they can be recovered through different non-destructive testing methods such as crosswell, vertical seismic profile, borehole logging as well as sonic tests. In all these methods, it is crucial to assess the effects of frequency on wave attributes including velocity and intrinsic attenuation. The dependency of per...

Journal: :فیزیک زمین و فضا 0
مجتبی نقوی دانشجوی کارشناسی ارشد ژئوفیزیک، گروه فیزیک زمین، مؤسسة ژئوفیزیک دانشگاه تهران، ایران ظاهر حسین شمالی استادیار، گروه فیزیک زمین، مؤسسة ژئوفیزیک دانشگاه تهران، ایران مهدی زارع دانشیار، پژوهشگاه بین المللی زلزله شناسی و مهندسی زلزله، تهران، ایران

in the present study, the q factor is obtained for the central alborz in iran using the lg coda method. the energy of a seismic wave decays while passing through a ‘real’ medium such as the earth which is not completely elastic. the decay in energy is due to non-elastic phenomena and is called intrinsic attenuation and is characterized with the q parameter, the large values of which represent s...

Journal: :civil engineering infrastructures journal 0
hasan ghasemzadeh assistant professor, k.n. toosi university of technology, civil engineering faculty, tehran, iran amir ali abounouri msc graduate, k.n. toosi university of technology, civil engineering faculty, tehran, iran

stress waves contain useful information about the properties of porous materials; they can be recovered through different non-destructive testing methods such as crosswell, vertical seismic profile, borehole logging as well as sonic tests. in all these methods, it is crucial to assess the effects of frequency on wave attributes including velocity and intrinsic attenuation. the dependency of per...

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