نتایج جستجو برای: acoustic coefficient

تعداد نتایج: 253198  

2010
R. Abbasi S. W. Barwick M. L. Benabderrahmane P. A. Evenson A. R. Fazely T. K. Gaisser H. Kolanoski D. J. Koskinen

Using the South Pole Acoustic Test Setup (SPATS) and a retrievable transmitter deployed in holes drilled for the IceCube experiment, we have measured the attenuation of acoustic signals by South Pole ice at depths between 190 m and 500 m. Three data sets, using different acoustic sources, have been analyzed and give consistent results. The method with the smallest systematic uncertainties yield...

Journal: :journal of computational applied mechanics 0
masoud ghasemian department of mechanical engineering, university of tehran, tehran, iran amir nejat department of mechanical engineering, university of tehran, tehran, iran

the current study presents the results of the aerodynamic noise prediction of the flow field around a naca 0012 airfoil at a chord-based reynolds number of 100,000 and at 8.4 degree angle of attack. an incompressible large eddy simulation (les) turbulence model is applied to obtain the instantaneous turbulent flow field. the noise prediction is performed by the ffowcs williams and hawkings (fw-...

2016
Lingjing Zhu Yixing Liu Zhenbo Liu

The crystallinity and acoustic-vibration parameters of Picea jezoensis, including specific Young’s modulus (E/ρ),coefficient of sound-radiation resistance (R), sound resistance (ω), and the ratio of Young’s modulus to the dynamic stiffness modulus (E/G), before and after heat treatment were measured and characterized. Conditions for the heat treatment included N2 as the protection gas and tempe...

Journal: :The Journal of the Acoustical Society of America 2015
Mika Kuroda Motoki Sasaki Kazutaka Yamada Nobuhiro Miki Takashi Matsuishi

The process by which sound is propagated in the head of a toothed whale is still a subject of discussion. Investigating the distribution of acoustic impedance calculated by density and Young's modulus is effective for quantitative comprehension because acoustic impedance determines the reflection coefficient of a sound wave. However, the sound propagation process of the toothed whale has been m...

1996
D. V. Khveshchenko M. Reizer

We study the principal aspects of the interaction between acoustic phonons and two-dimensional electrons in quantizing magnetic fields corresponding to even denominator fractions. Using the composite fermion approach we derive the vertex of the electron-phonon coupling mediated by the Chern-Simons gauge field. We estimate acoustic phonon contribution to electronic mobility, phonon-drag thermopo...

2011
Zeynab Raeesy Ladan Baghai-Ravary John S. Coleman

A new approach is proposed for quantifying the degree of articulator movement within a phoneme as a single scalar value, using vocal tract images captured using dynamic MRI. This indicates the degree of physical movement of the articulators involved in speech production, rather than the acoustic consequences of that movement. We go on to show that this is a valid method for characterising the o...

In this study, the change at rubbing surfaces has been investigated experimentally using an acoustic emission signal monitoring system. A steel ring is slipped on the surface of  a metallic sheet to simulate frictional conditions. The mechanical disturbances caused by the movement of the ring produce stress waves propagating along the sheet surface. The out of plane displacement of the sheet su...

ژورنال: ارگونومی 2013

Introduction: Noise pollution cause mental fatigue, concentration disturbance and learning loss in students during the training activities. This study aims to evaluate Noise pollution and the level of acoustical comfort in typical classrooms, and present treatment methods for improving acoustic comfort. Method: In cross sectional study, twenty classrooms in the seven faculty of Hamadan Univers...

2015
J. Piechowicz

Airborne sound insulation index of the noise barrier panel and the sound absorption coefficient of the barrier surface are the acoustic parameters that are usually determined in specialized laboratories, however they can be also determined in situ. Acoustic characteristics of a barrier include also the diffraction index difference determined from comparison of barriers with plain top edges and ...

2012
Dejan Markovic Christian Hofmann Fabio Antonacci Konrad Kowalczyk Augusto Sarti Walter Kellermann

This paper presents a novel model-based method for in-situ estimation of sound reflection coefficients in acoustic enclosures. The method uses a modeling engine for simulation of acoustic propagation and generation of the spatial pseudospectrum using a beamforming technique. The simulated pseudospectrum is matched with the measured pseudospectrum acquired by a real beamforming microphone array ...

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