Global ETD Search
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Showing 1 to 20 of 77 for “"Acoustic propagation"”.
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Acoustic Propagation in Poroelastic Media
The propagation of acoustic waves in porous media is of interest in a variety of areas, including oil well logging, the seepage of contaminants into ground water supplies, and the flow of fluids in packed beds. The aim of this work is to solve the equations of motion for the fluid and solid domains …
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Acoustic propagation near porous and elastic boundaries
… Ground Systems (FFLAGS) is formulated to predict acoustic propagation and acoustic-seismic coupling in the model layered system due to a point source in a horizontally stratified atmosphere. This is a full wave solution. Results are compared to those of existing propagation prediction methods. …
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High frequency acoustic propagation and modeling in stratified estuaries
Acoustic propagation measurements are made in a highly variable and stratified estuary using high frequency transducers (120kHz) on tripods placed across the main channel of the river flow. The measurements are taken in the Connecticut River across several tidal cycles, when the flood tide causes a …
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High Frequency Acoustic Propagation and Modeling in Stratified Estuaries
Acoustic propagation measurements are made in a highly variable and stratified estuary using high frequency transducers (120kHz) on tripods placed across the main channel of the river flow. The measurements are taken in the Connecticut River across several tidal cycles, when the flood tide causes a …
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Electromagnetic and acoustic propagation in strip lines and porous media
Wave propagation in two physical structures is described and analyzed in this dissertation. In the first problem, the propagation of a normally incident plane acoustic wave through a three dimensional rigid slab with periodically placed holes is modeled and analyzed. The spacing of the holes A and …
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Modeling studies of acoustic propagation through the Agulhas Current region
… mesoscale eddies. This requirement can be met by acoustic thermometry.
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A modal analysis of acoustic propagation in the changing Arctic environment
This work takes an in depth look at acoustic propagation through double duct sound speed profiles in the Arctic. While the traditional Arctic sound speed profile has a single surface duct, some portions of the Arctic have a sound speed profile which includes a second, lower duct. These double duct …
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Stochastic Dynamically Orthogonal Modeling and Bayesian Learning for Underwater Acoustic Propagation
… knowledge of the ocean environment and acoustic parameters makes reliable acoustic predictions challenging. This is due to the sparse and heterogeneous data, as well as to the complex ocean physics and acoustics dynamics, multiscale interactions, and large dimensions. There are thus …
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Acoustic propagation in nonuniform circular ducts carrying near sonic mean flows
… the wave-envelope technique is used to study the propagation of axisymmetric and spinning acoustic modes in hard-walled and lined nonuniform circular ducts carrying near sonic mean flows. This method is valid for large as well as small axial variations, as long as the mean flow does not separate. …
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The effect of internal waves on long range acoustic propagation in the ocean
The acoustic-internal wave interaction in an acoustic waveguide is investigated using wave techniques. Refractive index fluctuations due to the vertical displacements of the internal waves create an inhomogeneous waveguide. The analysis uses weak scattering theory based upon the Rytov perturbation …
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Analysis of acoustic propagation in the region of the New England continental shelfbreak
During July and August of 1996, a large acoustics/physical oceanography experiment was fielded in the Mid-Atlantic Bight, south of Nantucket Island, MA. Known as the Shelfbreak Front PRIMER Experiment, the study combined acoustic data from a moored array of sources and receivers with very high …
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Large eddy simulation of acoustic propagation in turbulent flow through ducts and mufflers
This research involves study of acoustic propagation of pulse in a simple expansion muffler, which is very often used in HVAC or automotive exhausts. A hybrid pressure-based compressible solver is developed and validated for a low Mach number flow simulation of acoustic pulse. This new solver is …
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Effect of myofibril length and tissue constituents on acoustic propagation properties of muscle
… components (sarcomere length) on the ultrasonic propagation properties. The scanning laser acoustic microscope (SLAM) was used to measure the attenuation coefficient, speed and heterogeneity index of all three samples at 100 MHz. The Daedal exposimetry system (DES) was used to determine both of …
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Analysis of acoustic propagation in the region of the New England continental shelfbreak
During July and August of 1996, a large acoustics/physical oceanography experiment was fielded in the Mid-Atlantic Bight, south of Nantucket Island, MA. Known as the Shelfbreak Front PRIMER Experiment, the study combined acoustic data from a moored array of sources and receivers with very high …
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Three-dimensional acoustic propagation through shallow water internal, surface gravity and bottom sediment waves
… physics of fully three-dimensional low frequency acoustic interaction with internal waves, bottom sediment waves and surface swell waves that are often observed in shallow waters and on continental slopes. A simple idealized model of the ocean waveguide is used to analytically study the properties …
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Hybrid Galerkin boundary element-wavenumber integration method for acoustic propagation in laterally inhomogeneous media
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1991.
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Three-dimensional acoustic propagation through shallow water internal, surface gravity and bottom sediment waves
… physics of fully three-dimensional low frequency acoustic interaction with internal waves, bottom sediment waves and surface swell waves that are often observed in shallow waters and on continental slopes. A simple idealized model of the ocean waveguide is used to analytically study the properties …
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Effects of internal waves on low frequency, long range, acoustic propagation in the deep ocean
… of long-range, deep-ocean, low-frequency, sound propagation experimental results obtained from the North Pacific Ocean. The statistics of acoustic fields after propagation through internal-wave-induced sound-speed fluctuations are explored experimentally and theoretically. The thesis starts with …
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Modeling three-dimensional acoustic propagation in underwater waveguides using the longitudinally invariant finite element method
Three-dimensional acoustic propagation in shallow water waveguides is studied using the longitudinally invariant finite element method. This technique is appropriate for environments with lateral variations that occur in only one dimension. In this method, a transform is applied to the …
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Application of the nonlinear progressive wave equation to simulate nonlinear acoustic propagation near an interface
Includes bibliographical references (leaves 37-38).
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