نتایج جستجو برای: waves

تعداد نتایج: 113311  

The present investigation analysis a problem of r­­­eflection and transmission at an interface of two micropolar orthotropic piezothermoelastic media. The basic equations and constitutive relations for micropolar orthotropic piezothermoelastic media for G-L theory are derived. The expressions for amplitude ratios corresponding to reflected and transmitted waves are derived analytically. The eff...

Journal: :iranian journal of medical physics 0
seyed ali shafiei assistant professor of medical physics, school of medicine, qom university of medical sciences, qom, iran

introduction many features, emerging from mathematical techniques, have been used in the analysis of brain signals. in this study, the physical quantity of “moment of inertia” (moi) was introduced as a feature to enhance high-frequency waves (hfws) in electroencephalography (eeg). materials and methods in this research, the recorded eegs from f3, f4, and cz points in 20 males were used. a total...

Journal: :international journal of advanced biological and biomedical research 2014
sedigheh rezaeyan mahsa rafati alashti somayyeh ahmadi ghasem kheyli azadeh khonsari mahdi nasiri seyed

medical plants are adapted to different kinds of dormancy to survive in the worst situations. regarding to ecological viewpoint, this kind of adaptation is very important in respect to restriction of genetic draft and decrease of genetic resource of medicinal plants. this leads to plant survival even after prolonged drought. since some of them are endangered species and in the other hand increa...

Journal: :international journal of marine science and engineering 2011
a. a. bidokhti a. shekarbaghani

ocean waters often show layered structures especially where exchange flow between two basins occurs. these structures are often attributed to processes such as double.diffusive convection, internal waves, turbulent modulated mixing. in this paper by examining the vertical structures of temperature, salinity and density, of the middle parts of caspian sea it is shown that such layered structure ...

Journal: :iranian journal of oil & gas science and technology 2014
behnam keshavarzi mohammad javad shojaei mohammad hossein ghazanfari cyrus ghotbi

it has been proved that ultrasonic energy can considerably increase the amount of oil recovery in animmiscible displacement process. although many studies have been performed on investigating theroles of ultrasonic waves, based on the best of our knowledge, little attention has been paid to evaluatewave attenuation parameter, which is an important parameter in the determination of the energydel...

Journal: :iranian journal of astronomy and astrophysic 0
neda amjadi astrophysics department, physics faculty, university of tabriz, tabriz, iran vahid abbasvand astrophysics department, physics faculty, university of tabriz, tabriz, iran d.m jassur astrophysics department, physics faculty, university of tabriz, tabriz, iran

in the current paper, we have studied the effect of dark energy on for-mation where dark energy exists in the background. for this purpose, we used both wmap9 and planck data to study how the radius changes with redshift in these mod-els. we used different data sets to fix the cosmological parameters to obtain a solution for a spherical region under collapse. the mechanism of structure formation f...

Journal: :iranian journal of astronomy and astrophysics 2014
iraj gholami

given the sensitivity of current ground-based gravitational wave (gw) detectors, any continuous-wave signal we can realistically expect will be at a level or below the background noise. hence, any data analysis of detector data will need to rely on statistical techniques to separate the signal from the noise. while with the current sensitivity of our detectors we do not expect to detect any tru...

Journal: :iranian journal of science and technology (sciences) 2007
s. a azarmsa

a boundary integral method is used to simulate spilling breakers. the bottom is also included inthe introduced closed boundary and the problem is directly solved in the physical plane. the method has beenshown to be remarkably stable, and no numerical instability has occurred in any of the calculations. theresults reveal that both the momentum and total energy are almost constant in time during...

Journal: :journal of modern processes in manufacturing and production 2013
mehdi jahngiri

high speed wind tunnels are widely used in the study of fluid flow behavior around various objects. the air flow in the starting step of supersonic wind tunnels is transient including strong shock waves caused by the interaction of the tunnel main stream and the boundary layer at walls. to arrive in running step, the tunnel must be designed so as these waves leave immediately the test section. ...

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