Results 131 to 140 of about 558 (180)
A sparse equivalent source method for near-field acoustic holography [PDF]
The Journal of the Acoustical Society of America, 2017 This 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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Near field acoustic holography with microphones on a rigid sphere (L) [PDF]
The Journal of the Acoustical Society of America, 2011 Spherical 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
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Interior near-field acoustical holography in flight
The Journal of the Acoustical Society of America, 2000In this paper boundary element methods (BEM) are mated with near-field acoustical holography (NAH) in order to determine the normal velocity over a large area of a fuselage of a turboprop airplane from a measurement of the pressure (hologram) on a concentric surface in the interior of the aircraft.
E G, Williams +4 more
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Surface decomposition method for near-field acoustic holography
The Journal of the Acoustical Society of America, 2012Near-field acoustic holography reconstruction of the acoustic field at the surface of an arbitrarily shaped radiating structure from pressure measurements at a nearby conformal surface is obtained from the solution of a boundary integral equation. This integral equation is discretized using the equivalent source method and transformed into a matrix ...
Nicolas P, Valdivia +3 more
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ACOUSTO-OPTIC SENSING FOR NEAR-FIELD ACOUSTIC HOLOGRAPHY
Inter-Noise 2022, 2023Near-field acoustic holography (NAH) is a very powerful and widely used technique for the study of complex acoustic radiators. NAH enables to quickly understand how a complex source radiates into the medium. The technique is particularly suitable at low frequencies.
SA VERBURG +2 more
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Measurement of confined acoustic sources using near-field acoustic holography
The Journal of the Acoustical Society of America, 2009Due to excessive reverberation or to the presence of secondary noise sources, characterization of sound sources in enclosed space is rather difficult to perform. In this paper a process layer is used to recover the pressure field that the studied source would have radiated in free space.
Langrenne, Christophe +2 more
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On the applicability of the spherical wave expansion with a single origin for near-field acoustical holography [PDF]
Journal of the Acoustical Society of America, 2009 The spherical wave expansion with a single origin is sometimes used in connection with near-field acoustical holography to determine the sound field on the surface of a source.
Peter Juhl +2 more
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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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Hybrid near-field acoustic holography
The Journal of the Acoustical Society of America, 2003Hybrid near-field acoustical holography (NAH) is developed for reconstructing acoustic radiation from an arbitrary object in a cost-effective manner. This hybrid NAH is derived from a modified Helmholtz equation least squares (HELS) formula that expands the acoustic pressure in terms of outgoing and incoming waves.
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Research on Patch Near-Field Acoustic Holography
Applied Mechanics and Materials, 2011Support vector regression is used to establish a kind of patch near-field acoustic holography. The regression functions are constructed by treating the measured data on the patch holography as training samples, and then the data outside the measurement aperture are extrapolated. The experimental results show that the extrapolation of the sound pressure
Hai Chao Zhu +3 more
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