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Near-field acoustical holography in an enclosed space
The Journal of the Acoustical Society of America, 1990In wind and water tunnels, the interaction of flow with rotating and nonrotating structures is a source of radiated noise. To characterize both the source and noise field radiated by sources operating in wind or water tunnels, near-field acoustical holography algorithms for the nonintrusive reconstruction of the velocity of the source and the complete ...
Charles J. Konzelman +1 more
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Near-field acoustic holography of acoustic radiation from structures
The Journal of the Acoustical Society of America, 2012There are some difficulties for conventional Near-field Acoustic Holography (NAH) to analyze acoustic radiation from a large scale structure. To solve the problem, a method for NAH of large scale structures was presented. In the method, the normal velocities or sound pressure at a few points on the surface of the structure are measured by transducers ...
Rongfu Mao, Zhimin Chen, Haichao Zhu
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Interior near-field acoustic holography based on finite elements
The Journal of the Acoustical Society of America, 2019This paper deals with the mathematical framework of near-field acoustic holography based on finite elements in application to the acoustic response of a fluid within a closed cavity to the enclosure boundary conditions. The finite element method is an effective implementation of the modal approach for arbitrary geometries and provides advantages for ...
Steffen, Ungnad, Delf, Sachau
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Near field acoustic holography with microphones on a rigid sphere (L)
The Journal of the Acoustical Society of America, 2011Spherical near field acoustic holography (spherical NAH) is a technique that makes it possible to reconstruct the sound field inside and just outside a spherical surface on which the sound pressure is measured with an array of microphones. This is potentially very useful for source identification. The sphere can be acoustically transparent or it can be
Finn, Jacobsen +3 more
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A sparse equivalent source method for near-field acoustic holography
The Journal of the Acoustical Society of America, 2017This study examines a near-field acoustic holography method consisting of a sparse formulation of the equivalent source method, based on the compressive sensing (CS) framework. The method, denoted Compressive–Equivalent Source Method (C-ESM), encourages spatially sparse solutions (based on the superposition of few waves) that are accurate when the ...
Efren, Fernandez-Grande +2 more
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THEORY AND BOUNDARY ELEMENT METHODS FOR NEAR-FIELD ACOUSTIC HOLOGRAPHY
Journal of Computational Acoustics, 2005We consider the problem of recovering surface vibrations from acoustic pressure measurements taken in the interior or the exterior of a region. We give two formulations of the problem. One is based on a representation of the pressure as layer potentials and the other is based on approximation by a class of specific solutions to the Helmholtz equation.
Delillo, Thomas +2 more
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Near-field acoustical holography—interior problems
The Journal of the Acoustical Society of America, 1997Near-field acoustical holography (NAH) provides a practical solution to a challenging inverse problem: Calculation of the normal velocity on the surface of a vibrator from the pressure field measured in the acoustic near field of the vibrating surface.
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A comparison of SONAH and IBEM for near-field acoustic holography
The Journal of the Acoustical Society of America, 2008Among the popular techniques for acoustic source identification in complex environments are the Statistically Optimal Near Acoustic Holography (SONAH) and the Inverse Boundary Element Method (IBEM). These two methods are quite different regarding the underlying assumptions and the practical implementations: Whereas SONAH performs the back-propagation ...
Peter Juhl, Jesper Gomes
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Near-field acoustical holography in enclosed spaces
The Journal of the Acoustical Society of America, 2003In enclosed spaces, the locations of surfaces from which most of the noise radiation occurs can be difficult to determine in the presence of reverberation and contributions from other sources. By using microphones configured in an array that confirms to the surface of interest, it should be possible to map the acoustic field inside the enclosed space ...
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Applications of Near-field Acoustic Holography on Small Apertures
The Journal of the Acoustical Society of America, 2008Small, finite measurement apertures are a major impediment for accurate and fast application of near-field acoustic holography (NAH). In theory, FFT-based NAH methods are very powerful and acquire extremely fast inverse calculations of the sound field.
Rick Scholte +3 more
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