Results 181 to 190 of about 1,666 (211)
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Absorption of acoustic waves by sunspots
Solar Physics, 1992Observations of the scattering of acoustic waves by sunspots show a substantial deficit in scattered power relative to incident power. A number of calculations have attempted to model this process in terms of absorption at the magnetohydrodynamic Alfven resonance.
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Inhomogeneous absorption and geometric acoustics
The Journal of the Acoustical Society of America, 1998The conventional formulation of geometric acoustics in the presence of inhomogeneous (spatially varying) absorption is examined. This formulation is found to fail under conditions of multipath propagation, because interference between ray paths is not taken into account when the absorptive losses are calculated.
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Materials and DesignWe propose an acoustic-mechanical metasurface with simultaneous sound absorption and vibration reduction functionalities. This acoustic-mechanical feature results from a nonlocal coupling effect in the designed composite meta-structure.
Yifan Zhu, Haiyan Fan
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Acoustic absorption in amorphous silicate down to 1 K
Il Nuovo Cimento B Series 11, 1976The acoustic absorption in amorphous silica was measured between 1 K and 20 K and at frequencies between 15 and 65 MHz. It was shown that in the range (3÷5) K there exists an absorption peak whose position is temperature dependent, thus indicating a thermally activated relaxation process.
Ballaro' S. +4 more
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A Small Acoustical Tube for Measuring Absorption of Acoustical Materials in Auditoriums
The Journal of the Acoustical Society of America, 1946A small acoustical tube is described, which is suitable for measuring absorption coefficients of acoustical materials over a limited frequency range. This instrument is useful for checking the acoustical characteristics of materials after they have been applied to the walls of theaters, studio review rooms, and other auditoriums.
D. P. Loye, R. L. Morgan
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Nonresonant acoustic absorption of Ising magnet
Theoretical and Mathematical Physics, 1994Zubarev's nonequilibrium statistical operator method is used to construct a theory of the nonresonant acoustic absorption of the linear Ising magnet, the basic Hamiltonian of which is of the two-particle kind and is treated without approximations. The frequency dependence of the absorption is determined and found to differ analytically from the well ...
I. S. Donskaya +2 more
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Sound Absorption Coefficients and Acoustic Impedance
The Journal of the Acoustical Society of America, 1941The relation between normal acoustic impedance and the various types of absorption coefficient has been discussed and specific formulas for the coefficients in terms of acoustic impedance have been published. Contours of constant absorption coefficient plotted as a function of the real and imaginary parts of acoustic impedance plotted on a linear scale
Richard L. Brown, Philip M. Morse
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Acoustical absorption by materials in a nacelle of turbojet
The Journal of the Acoustical Society of America, 2013The paper discusses the absorption of certain materials with different acoustic properties used in a nacelle of aircraft is investigated using numerical model. A model 2-D with the configuration of axisymmetrical and the differential equations of the Continuity and Helmholtz equation is realized, it couples a finite element description with a boundary ...
Ibanez R. Carlos, Panneton Raymond
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Broadband sound absorption using multiple hybrid resonances of acoustic metasurfaces
International Journal of Mechanical Sciences, 2022Hyeonbin Ryoo, Wonju Jeon
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Ultra-broadband acoustic absorption with inhomogeneous high-order Fabry–Pérot resonances
APL Materials, 2023Xiaoli Liu, Jiu Hui Wu, Fuyin Ma
exaly