Results 261 to 270 of about 33,703 (304)

Interlaboratory comparisons of acoustic emission spectra

NDT International, 1980
Abstract A procedure has been developed whereby acoustic emission frequency spectra can be corrected for the variable effects of specimen geometry, couplant, and transducer characteristics. The results of several experiments on 7039 Al show that quantitative agreement can be obtained between laboratories for the spectral shapes and amplitudes of ...
S.J. Acquaviva, D. Birchon, J.M. Carlyle, J.G. Faller, L.J. Graham, S.D. Hart, S.L. McBride, I.G. Scott, D.E.W. Stone, H.H. Vanderveldt   +9 more
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Amplitude spectra of acoustic pulses in the ocean

The Journal of the Acoustical Society of America, 1973
An acoustic pulse propagating the ocean encounters weak thermal patches that scatter energy. If these patches are moving with a mean current perpendicular to the direction of propagation, a temporal fluctuation in the pulse-averaged amplitude occurs. This study calculates the temporal frequency spectrum of the pulse-to-pulse amplitude fluctuations and ...
Edmund H. Brown, Steven F. Clifford
openaire   +1 more source

Electromagnetic and Acoustic Emission Fine Spectra

Advanced Materials Research, 2006
A new measuring method for the detection of fine spectra of electromagnetic and acoustic emission (EME and AE) signals from small cracks is described. It requires wide band ultra-low noise amplifiers, analogue filters, the optimization of signal to noise ratio of sensors and the application of noise elimination methods.
Josef Sikula, J. Majzner, P. Sedlak, Yasuhiko Mori   +3 more
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On acoustic turbulence spectra in a “dusty” plasma

Physics Letters A, 1994
Abstract In a collisionless “dusty” plasma, where both ion-sound and dust-sound waves exist, the local spectra of isotropic sound turbulence are obtained. They are determined by decays of ion-sound waves into ion-sound and dust-sound waves and by scattering of dust-sound waves on dust particles.
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Acoustical determinations of bubble-size spectra

The Journal of the Acoustical Society of America, 1977
The exact integration of the equations for acoustical cross sections of bubbles is considered to show when the dependence of the bubble number on radius can be determined by scatter and attenuation experiments in a liquid containing a broad spectrum of bubble radii.
openaire   +1 more source

Identification of acoustic spectra for fault detection in induction motors

2013 Africon, 2013
In this paper, we study fault detection problem for induction motors by using a recently developed cross-power spectral density estimation algorithm from sound measurements. In a test rig, from multiple experiments the sound data were collected by an array of five-microphones placed hemispherically around motors in a reverberant and noisy room.
Hüseyin Akçay, Emin Germen
openaire   +2 more sources

Information Content of Acoustic Attenuation Spectra

Particle & Particle Systems Characterization, 2002
In recent years ultrasonic attenuation spectroscopy has gained much attention as a method for the characterisation of concentrated dispersions. Several publications have shown, that this method allows the accurate determination of particle size. In particular for submicron dispersions there is, however, some uncertainty to which degree the details of a
Frank Babick, Siegfried Ripperger
openaire   +1 more source

Acoustic Spectra from Turbulent Jets

The Journal of the Acoustical Society of America, 1971
One of the interesting and important problems involving turbulent jets is that of determining the spectrum of the radiated sound. This has proved to be a difficult theoretical problem because the space-time correlation of the velocity is central in the prediction of such sound characteristics.
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Method of invariant manifolds and regularization of acoustic spectra

Transport Theory and Statistical Physics, 1994
Abstract A new approach to the problem of reduced description for Boltzmann-type systems is developed. It involves a direct solution of two main problems: thermodynamicity and dynamic invariance of reduced description. A universal construction is introduced, which gives a thermodynamic parameterization of an almost arbitrary approximation.
A. N. Gorban, I. V. Karlin
openaire   +1 more source

Spectra of ion acoustic plasma instability

The Physics of Fluids, 1977
An experimental study of ion acoustic plasma turbulence in a collision-dominated positive column is presented. Linear theory predictions, which include ion Landau damping and the effects of a dc electric field, are shown to agree with measured values of convective growth rates.
openaire   +1 more source