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 20 of 86 for “"Sound propagation"”.
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Sound propagation in woodland
A review of past research into sound propagation in woodland is presented. The attenuation of sound in woodland is small between about 800 and 2000Hz and greater at low and high frequencies. Attenuation measurements made in three contrasting woodlands are presented and compared with theoretical …
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Sound propagation in streets.
Massachusetts Institute of Technology. Dept. of Mechanical Engineering. Thesis. 1974. M.S.
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Sound propagation around underwater seamounts
… and methods which improve the understanding of sound propagation around underwater seamounts. The depth-dependent sound velocity profile of typical ocean waveguides force sound to travel in convergence zones about a minimum sound speed depth. This ducted nature of the ocean makes modeling the …
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Sound Propagation in Inhomogeneous Media
Outdoor sound propagation is of interest in community noise problems, for example noise prediction. The interaction of sound with the ground is also of interest in remote surveillance by acoustic and seismic sensors. In this thesis, previous work concerned with sound propagating in a layered …
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Sound propagation in urban spaces
Thesis. 1976. Sc.D.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering.
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Sound propagation around underwater seamounts
… field of a seamount at many locations at sound path ranges of order 500 km, utilizing a rich bathymetry and sound velocity database. Convergence zones in the forward-scattered field of seamounts at long-range are observed, created by higher order mode coupling and blockage. Acoustic ray …
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Sound propagation around underwater seamounts
… and methods which improve the understanding of sound propagation around underwater seamounts. The depth-dependent sound velocity profile of typical ocean waveguides force sound to travel in convergence zones about a minimum sound speed depth. This ducted nature of the ocean makes modeling the …
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Fast Sound Propagation in Binary Fluid Mixtures
… hydrodynamic regime. One can call this mode fast sound, because, like ordinary sound, it propagates, but it is faster. The most important point is that the fast sound is associated with the dynamics of the light component only. In the thesis I explain how this phenomenon could be observed in light …
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Sound Propagation via Narrow Beam Audio Projection
… ago. It consists in the generation of secondary sound waves by the propagation of two collimated primary ultrasonic waves at a close frequency. The sound wave generated corresponds to the difference of the frequencies propagated and its existence is independent from the ultrasonic waves, but it …
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A low frequency underwater sound propagation model
All wave-theoretic underwater sound propagation models attempt to derive the acoustic field originating from a sound source in a specific environment by either solving the wave equation directly or by solving an approximation there-of. This dissertation describes a normal mode direct solution with …
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Models for sound propagation in suspensions and emulsions
Theoretical and experimental work on sound propagation in suspensions and emulsions is reviewed. Three theoretical approaches are identified: scattering theory, coupled phase theory and porous media theory. Coupled phase theory is extended and compared analytically and numerically to scattering and …
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A computer model for sound propagation around conical seamounts
… a technique for computing the long-range sound pressure field around a penetrable conical seamount. The pressure field is generated by a harmonic point source. The seamount is positioned in a vertically stratified ocean. It is modeled as an outgrowth of the sediment layer covering the …
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Time-Domain Simulation of Sound Propagation in Frequency-Dependent Materials
This dissertation investigates sound propagation in frequency-dependent materials. The study provides an improved understanding of how to numerically model the porous impedance materials more accurately under the conditions of complicated geometries. The finite difference time-domain (FDTD) method …
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Quantifying the effect of dispersion in Continental Shelf sound propagation
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2002.
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Acoustic optimisation and prediction of sound propagation in turbofan engine ducts
… in this thesis explores the prediction of noise propagation and<br/>radiation in turbofan engine intakes and bypass ducts, and the optimisation of noise attenuation<br/>by using acoustic liners. A commercial FE/IE code ACTRAN/TM is used<br/>within two shell programs; B-induct for bypass ducts and …
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Prediction and control of sound propagation in turbofan engine bypass ducts
This thesis contains original research into the propagation of sound in acoustically lined ducts<br/>with flow. The motivation for this work is the requirement to predict the sound attenuation of<br/>acoustic liners in the bypass duct of modern turbofan aeroengines. The liners provide the …
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Underwater sound propagation and acoustic communication in a time-varying shallow estuarine environment
… which can significantly influence the underwater sound propagation and moreover, underwater acoustic communications. In order to perform reliably and effectively in such complex time-varying shallow-water ocean environments, next-generation underwater acoustic communication systems need an all new …
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A Comprehensive Hamiltonian Atmospheric Sound Propagation Model for Prediction of Wind Turbine Noise
… farms. However, modelling and simulating WTN propagation over large distances is challenging due to the complexity of atmospheric conditions. Real temperature, wind velocity and relative humidity measurements typically show a characteristic nonlinear behavior. A comprehensive propagation model …
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A numerical hybrid method for modeling outdoor sound propagation in complex urban environments
Prediction of the sound field in large urban environments has been limited thus far by the heavy computational requirements of conventional numerical methods such as boundary element (BE), finite-difference time-domain (FDTD), or ray-tracing methods. Recently, a considerable amount of work has been …
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