Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 10 of 10 for “"Acoustic surface waves"”.
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Excitation of Acoustic Surface Waves by Turbulence
Acoustic metamaterials have been shown to support acoustic surface waves when excited by a broadband signal in a quiescent environment and these waves could be manipulated by varying the geometry of the structure making up the metamaterial. The study presented here demonstrates the generation of …
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Turbulent Boundary Layers over Rough Surfaces: Large Structure Velocity Scaling and Driver Implications for Acoustic Metamaterials
… to initiate the viability of controlling acoustic waves driven by pressure fluctuations from flow. A turbulent boundary layer scaling analysis was performed on zero-pressure-gradient turbulent boundary layers over rough surfaces, for 30,000≤〖Re〗_θ≤100,000. Relationships between fluctuating …
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Directionally Sensitive Sensor Based on Acoustic Metamaterials
… microphone arrays are valuable tools for aeroacoustic measurements that can measure the directivity of multiple acoustic sources. However, when deployed in closed test-section wind tunnels, the acoustics suffer due to intense pressure fluctuations contained in the wall-bound turbulent boundary …
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Acoustic propagation near porous and elastic boundaries
… on an elastic halfspace, to incident plane waves, is developed to include further porous elastic layers within the ground. The dynamic properties of the porous elastic layers are modelled using a modified Biot formulation. Using the same boundary conditions a Fast Field algorithm for Layered …
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Analysis of acoustic communication channel characterization data in the surf zone
… characterization experiment for the underwater acoustic communication channel was carried out at Scripps Pier in May 1999. The experiment investigated acoustic transmission in very shallow water and breaking waves. In analyzing the data, several questions arose. The majority of the acoustic …
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An experimental study of air entrainment by breaking waves
Breaking waves charge the surface layer of the ocean with small air bubbles which play an important role in air-sea gas transfer and in underwater acoustics near the ocean surface. This work reports on a series of laboratory and field experiments on the measurement on air entrainment by breaking …
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Acoustic travel time perturbations due to an internal tide and internal wave field in the Barents Sea
… mooring of the array. Modal perturbations in acoustic pulse travel time and the travel time covariance are calculated and compared for consistency to a simple ray model. These perturbations are small for the modal arrivals that the vertical acoustic array which was deployed is expected to …
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Wavelet transform analysis of seismic data
Not available
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Amplitude fluctuation effects in shallow water acoustic scattering by internal waves
… the amplitude fluctuation effects in acoustic scattering due to shallow water internal waves. Theoretically, it uses the adiabatic approximation and perturbation methods to statistically evaluate acoustic transmission fluctuations caused by internal waves in the ocean; it also …
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Shipboard and satellite observations of upper ocean velocity and transport variability in the Gulf Stream
Acoustic doppler velocities are combined with velocity profiles generated from XBT measurements to produce estimates of the flow field between Bermuda and the eastern coast of the United States. Repeated shipboard measurements along an ascending GEOSAT subtrack between Bermuda and Cape Cod allow …