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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
291

Acoustic Resonance in a Cavity under a Subsonic Flow

Alvarez, Jose Oliverio January 2005 (has links)
Acoustic resonances leading to high unsteady pressure levels may occur in flow past cavities. The resonance involves a coupling between the downstream-propagating instability wave on the shear layer spanning the open face of the cavity, and acoustic waves propagating within and external to the cavity. These elements of the disturbance field are coupled by the scattering processes that occur at the upstream and downstream ends of the cavity. We develop a theoretical prediction method that combines propagation models in the central region of the cavity with scattering models for the end regions. In our analyses of the scattering processes at the cavity ends, the square-corner geometry is treated exactly, by a method employing the Wiener--Hopf technique. The shear layer is approximated as a vortex sheet in the edge scattering analyses, but finite shear-layer thickness is accounted for in analyzing the propagation of the waves along the length of the cavity. The global analysis leads to a prediction for the resonant frequencies which has a form similar to the Rossiter formula, but contains no empirical constants. In addition to prediction of the frequency, our theory determines the temporal growth or decay rate of each mode. Finally, our theory also predicts the influence of secondary feedback loops involving other components of the unsteady field. Comparisons of the predictions with existing experimental data are made.
292

Implementation of adaptive noise cancellation in the diving environment

Al-Kindi, Manal Jamil January 1988 (has links)
No description available.
293

Enhanced signal processing of pulsed doppler ultrasound

Keenan, Desmond Barry January 1998 (has links)
No description available.
294

On the psychoacoustic design of pitch detection algorithms

Barnes, Christopher Michael January 1995 (has links)
No description available.
295

Vibrations of orthotropic spherical shells

De Souza, V. C. M. January 1980 (has links)
No description available.
296

Sound propagation over rigid porous layers

Howarth, Craig January 1991 (has links)
No description available.
297

Adaptive system modelling for active attenuation of sound

Wong, Lawrence Yik-Lung January 1992 (has links)
No description available.
298

Sound propagation over mixed impedances

Heap, N. W. January 1982 (has links)
No description available.
299

The effect of geometry on acoustic emission

El-Dardiry, S. M. A. January 1980 (has links)
No description available.
300

The propagation and reception of wide-band ultrasonic pulses

Weight, J. P. January 1982 (has links)
No description available.

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