ACTIVE CANCELLATION OF ACOUSTIC PRESSURE AND PARTICLE VELOCITY IN THE NEAR FIELD OF A SOURCE

1999 ◽  
Vol 221 (1) ◽  
pp. 85-116 ◽  
Author(s):  
J. García-Bonito ◽  
S.J. Elliott
Keyword(s):  
Particle Velocity ◽  
Acoustic Pressure ◽  
Near Field ◽  
Active Cancellation

scholarly journals Patch near field acoustic holography based on particle velocity measurements

2009 ◽  
Vol 126 (2) ◽  
pp. 721-727 ◽  
Author(s):  
Yong-Bin Zhang ◽  
Finn Jacobsen ◽  
Chuan-Xing Bi ◽  
Xin-Zhao Chen
Keyword(s):  
Particle Velocity ◽  
Near Field ◽  
Velocity Measurements ◽  
Acoustic Holography

scholarly journals Geoacoustic inversion based on both acoustic pressure and particle velocity

2006 ◽  
Vol 120 (5) ◽  
pp. 3355-3356
Author(s):  
A. Vincent van Leijen ◽  
Jean‐Pierre Hermand ◽  
Kevin B. Smith
Keyword(s):  
Particle Velocity ◽  
Acoustic Pressure ◽  
Geoacoustic Inversion

Modal Analysis of a Loudspeaker and Its Associated Acoustic Pressure Field

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Derek Kuo ◽  
Y. C. Shiah ◽  
Jin H. Huang
Keyword(s):  
Modal Analysis ◽  
Sound Pressure ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
Near Field ◽  
Numerical Convergence ◽  
Supported Membrane ◽  
Near Field Sound ◽  
Elastically Supported ◽  
Field Sound

This paper presents a modal analysis and the sound pressure field for the vibrator membrane of an actual portable loudspeaker. Unlike the conventional way to model the membrane’s edge under a simply supported condition, the present approach takes the glued edge to be elastically supported. With theoretical derivations for such treatment, this paper also presents the associated near-field and far-field sound pressures that have not been reported in the open literature. Fundamentally, calculation of the near-field sound pressure solution for the elastically supported membrane has difficulty with numerical convergence. In this paper, integral regularization is employed to enforce the convergence. From the viewpoint of acoustic engineers, the analysis may effectively help to tailor the design of a loudspeaker that caters to consumers’ preference.

scholarly journals On Sparse Reconstructions in Near-Field Acoustic Holography Using the Method of Superposition

2016 ◽  
Vol 24 (03) ◽  
pp. 1650009 ◽  
Author(s):  
Nadia M. Abusag ◽  
David J. Chappell
Keyword(s):  
Acoustic Pressure ◽  
Numerical Study ◽  
Near Field ◽  
Source Surface ◽  
Data Sets ◽  
Internal Source ◽  
General Will ◽  
Numerical Solution Methods ◽  
Solution Methods ◽  
Data Points

The method of superposition is proposed in combination with a sparse [Formula: see text] optimization algorithm with the aim of finding a sparse basis to accurately reconstruct the structural vibrations of a radiating object from a set of acoustic pressure values on a conformal surface in the near-field. The nature of the reconstructions generated by the method differs fundamentally from those generated via standard Tikhonov regularization in terms of the level of sparsity in the distribution of charge strengths specifying the basis. In many cases, the [Formula: see text] optimization leads to a solution basis whose size is only a small fraction of the total number of measured data points. The effects of changing the wavenumber, the internal source surface and the (noisy) acoustic pressure data in general will all be studied with reference to a numerical study on a cuboid of similar dimensions to a typical loudspeaker cabinet. The development of sparse and accurate reconstructions has a number of advantageous consequences including improved reconstructions from reduced data sets, the enhancement of numerical solution methods and wider applications in source identification problems.

scholarly journals Acoustic Pressure and Particle Velocity for Spatial Filtering of Bottom Arrivals

2019 ◽  
Vol 44 (1) ◽  
pp. 179-192 ◽  
Author(s):  
Paulo Felisberto ◽  
Paulo Santos ◽  
Sergio M. Jesus
Keyword(s):  
Particle Velocity ◽  
Acoustic Pressure ◽  
Spatial Filtering

Flow-Excited Acoustic Resonance of Isolated Cylinders in Cross-Flow

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Nadim Arafa ◽  
Atef Mohany
Keyword(s):  
Particle Velocity ◽  
Acoustic Pressure ◽  
Excited Level ◽  
Cross Flow ◽  
Acoustic Resonance ◽  
Excitation Level ◽  
Linear Superposition ◽  
The Cross ◽  
Particle Velocities ◽  
Mode A

The flow-excited acoustic resonance of isolated cylinders in cross-flow is investigated experimentally where the effect of the cylinder(s) proximity to the acoustic particle velocity nodes of the cross-modes is presented in this paper. For the case of a single cylinder, the cylinder's location does not significantly affect the vortex shedding process; however, it affects the excitation level of each acoustic cross-mode. When the cylinder is moved away from the acoustic particle velocity antinode of a specific acoustic cross-mode, a combination of the cross-modes is excited with intensities that seem to be proportional to the ratio of the acoustic particle velocities of these modes at the cylinder's location. For the cases of two and three hydrodynamically uncoupled cylinders positioned simultaneously side-by-side in the duct, it is observed that the first three acoustic cross-modes are excited. When one cylinder is positioned at the acoustic particle velocity antinode of a specific cross-mode and another cylinder is positioned at its acoustic particle velocity node, i.e., a cylinder that should excite the resonance and another one that should not excite it, respectively; the excitation always takes over and the resonance occurs at a further elevated levels. It is also observed that the acoustic pressure levels in the cases of multiple cylinders are not resulting from a linear superposition of the excited level obtained from each individual cylinder which indicates that the removal of cylinders at certain locations may not be a viable technique to eliminate the acoustic resonance in the case of tube bundles.

Elastodynamic near-field of a finite, propagating tensile fault

1972 ◽  
Vol 62 (3) ◽  
pp. 675-697 ◽  
Author(s):  
N. A. Haskell ◽  
K. C. Thomson
Keyword(s):  
Numerical Integration ◽  
Particle Velocity ◽  
Fault Plane ◽  
Near Field ◽  
Infinite Medium ◽  
Displacement Discontinuity ◽  
Wave Form ◽  
Acceleration Wave ◽  
Ramp Function ◽  
Wave Forms

Abstract Displacement, particle velocity, and acceleration wave forms in the near-field of a finite, propagating tensile fault have been computed by numerical integration of the Green's function integrals for an infinite medium. The displacement discontinuity (dislocation) on the fault plane is assumed to have the form of a unilaterally propagating, finite ramp function in time. Computer generated wave-form plots are presented for a variety of close-in locations with respect to the fault plane and for two different fault lengths.

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