نتایج جستجو برای: acoustic wave amplification

تعداد نتایج: 345588  

The acoustic wave velocity depends on elasticity and density at most materials, but because of anisotropy and especially piezoelectric coupling effect, the acoustic wave propagation at piezoelectric based crystalloacoustic materials, is an applied and challenging problem. In this paper, using modified Christoffel's equation based on group velocity concept, the effect of anisotropy and piezoelec...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علامه طباطبایی - دانشکده روانشناسی و علوم تربیتی 1386

چکیده ندارد.

2013
G. Penelet M. Bruneau

The aim of this paper is to study the influence of the shape of the temperature distribution on the thermoacoustic amplification in an annular thermoacoustic prime mover. An analytical model is presented and the acoustic field in the whole device is computed for an arbitrary temperature distribution. The obtained results demonstrate dependence of the thermoacoustic amplification not only on the...

2000
K. Murawski

We examine the influence of a random flow that occurs in the convection zone on frequencies of the solar acoustic oscillations. Using a perturbative method the dispersion relation is derived in the case of a random flow that is parallel to the wave propagation. This relation is subsequently solved numerically for various parameters of the random field to find the frequencies of the random acous...

Massah, H.R., Momeni-Masuleh, S.H., Setvati-Zirak, A.,

Investigating waves propagation’s equation in the atmosphere is one of the important and widely used issues in various sciences, which has attracted many researchers. A type of propagating waves is an acoustic-gravity wave. These type of waves have a lot of stationarity properties and can be propagate to a high altitude in the atmosphere. The equation of acoustic-gravity wave propagation is a h...

Journal: :iranian journal of public health 0
m shayeghi dept. of medical entomology and vector control, school of public health, tehran mh dehghani dept. of environmental health engineering, school of public health, tehran university of medical sci am fadaei dept. of environmental health engineering, school of public health, tehran university of medical sci

background: organophosphorus pesticides are one of the most prevalent usages for pest control in the country. such pesti­cides enter into water sources by different routes. since drinking of contaminated water at the higher doses than the standard level, may causes undesirable effects to human health and ecosystem. the object of this research was to investigate the ef­fect of various parameters...

Journal: :international journal of environmental research 2012
a.r. noorpoor a. sadighzadeh h. habibnejad

the removal of fine particles less than 2.5 μm in diameter generated from industrial plantsrepresents a serious challenge in air pollution abatement. these particles can penetrate deeply into the lungs and are difficult to remove by cyclones, electrostatic precipitators, and other conventional separation devices. in this paper, the influence of acoustic waves on removing aerosol particles from ...

2014
Kyungjun Song Kiwon Kim Shin Hur Jun-Hyuk Kwak Jihyun Park Jong Rak Yoon Jedo Kim

The inherent attenuation of a homogeneous viscous medium limits radiation propagation, thereby restricting the use of many high-frequency acoustic devices to only short-range applications. Here, we design and experimentally demonstrate an acoustic metamaterial localization cavity which is used for sound pressure level (SPL) gain using double coiled up space like structures thereby increasing th...

The mathematical modeling of the acoustic wave propagation in seawater is the basis for realizing goals such as, underwater communication, seabed mapping, advanced fishing, oil and gas exploration, marine meteorology, positioning and explore the unknown targets within the water. However, due to the existence of various physical phenomena in the water environment and the various conditions gover...

Journal: :international journal of civil engineering 0
jafar najafizadeh no. 21, arghavan st., north dibajee, farmanieh, tehran, islamic republic of iran mohsen kamalian no. 21, arghavan st., north dibajee, farmanieh, tehran, islamic republic of iran mohammad kazem jafari no. 21, arghavan st., north dibajee, farmanieh, tehran, islamic republic of iran naser khaji faculty of civil and environmental engineering, tarbiat modares university

in this paper, an advanced formulation of the spectral finite element method (sfem) is presented and applied in order to carry out site response analysis of 2d topographic structures subjected to vertically propagating incident in-plane waves in time-domain. the accuracy, efficiency and applicability of the formulation are demonstrated by solving some wave scattering examples. a numerical param...

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