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 19 of 19 for “"propagation of sound"”.
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Propagation of sound in attenuating ducts containing absorptive strips
Thesis (Ph.D.) Massachusetts Institute of Technology. Dept. of Physics, 1953.
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Propagation Of Sound In The Vicinity Of Rigid Porous Interfaces
<p>Propagation of sound in the vicinity of rigid porous interfaces is investigated systematically to facilitate the acoustical characterization of sound absorption materials for noise reduction applications. Various rigid porous interfaces are considered: (1) a semi-infinite porous layer; (2) a …
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Model study of the propagation of sound from V/STOL aircraft into urban environs.
Massachusetts Institute of Technology. Dept. of Mechanical Engineering. Thesis. 1973. M.S.
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Application of ray acoustics to the propagation of sound in ducts containing sheared flows
Ray acoustics has been applied to the propagation of sound waves in a homogeneous moving medium with sheared flow bounded by the hard walls of a duct. Differential equations describing the ray trajectories and spreading losses along each ray were developed and solved numerically for a range of …
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The problem of the stethoscope: an enquiry, experimental and philosophical, into the properties of this instrument and the physics of auscultation
… back to the time when I first entered the class of Clinical Medicine. I had previously, while on war service, been interested in the propagation of sound in sea water, and finding that acoustics played so important a part in the diagnosis of pulmonary and cardiac conditions, I naturally sought to …
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A source-extraction based coupling method for computational aeroacoustics
This thesis involves the computation of aerodynamically generated sound using a source-extraction based coupling approach. In the present coupling method, the unsteady aerodynamic calculation and the calculation of sound propagation are separated artificially. A set of acoustic perturbation …
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Acoustic sounding of snow water equivalent
… conducted by investigators who have examined the propagation of sound in snow, digital signal processing was used to determine acoustic pressure wave reflection coefficients at the interfaces between 'layers' indicative of changes in acoustic impedance. Using an iterative approach involving …
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Quantum transport in strongly interacting, ultracold fermi gases in box potentials
Transport of strongly interacting fermions is crucial for systems as varied as high-𝑇 subscript 𝑐 superconductors, twisted bi-layer graphene, nuclear fission, and neutron stars. In this thesis, I will describe the experiments we performed to measure the transport properties of a …
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Space, time and acoustics
This thesis describes the development of new concepts in acoustical analysis from their inception to implementation as a computer design tool. Research is focused on a computer program which aids the designer to visually conceive the interactions of acoustics within a geometrical~y defined …
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Sound Waves and Turbulence in Two-dimensional Bose Gases
… first one we focus on the equilibrium properties of the gas close to the Berezinskii-Kosterlitz-Thouless (BKT) phase transition, while in the second one we study the out-of-equilibrium dynamics of the system. Our experiments are performed using a gas of $^{39}$K atoms confined in a 2D box trap, …
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An inverse method for obtaining the attenuation profile and small variations in the sound speed and density profiles of the ocean bottom
The acoustic properties of marine sediments have a direct effect on the propagation of sound in the ocean. In the frequency range of interest (50 - 500 Hz) the sediment can be modelled as a fluid. Assuming horizontal stratification of the ocean bottom, the acoustic parameters of interest are the …
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The effect of wind turbulence on noise barrier performance
… has been carried out into the effect of wind turbulence on the propagation of sound over open grassland both with, and without, a 2.4m high barrier present. Sound bursts, derived from a variety of original signals, were generated using a horn loudspeaker and the resulting levels were …
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Propagation of zero sound in liquid He3
The propagation of sound in liquid He3 was observed at a pressure of 0.32 atm and at fre~quencies of 15.4 and 45.5 MHz down to a temperao 0 -3 0 . ture T* of 2m K (1m K = 10 K) on the temperature scale va11d for the Curie-law magnetic susceptibility of powdered cerium magnesium nitrate in the form …
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Audioptimization : global-based acoustic design
… difficult problem, because the human perception of sound depends on such things as decibel level, direction of propagation, and attenuation over time, none of which are tangible or visible. The advent of computer simulation and visualization techniques for acoustic design and analysis has yielded …
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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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An Energy Diffusion Model for Interior Acoustics with Structural Coupling Using the Laplace Transform Boundary Element Solution
Knowledge of the indoor propagation of sound has many important applications including acoustic prediction in homes, office buildings, stores, and schools, and the design of concert halls, auditoriums, classrooms, and factories. At low frequencies, interior acoustics are analyzed with the wave …
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A hybrid method for impulse response measurements with synthesized musical tones and Masked-MLS Stimuli
… responses or transfer functions are descriptions of acoustic and audio transmission channels, which completely characterise point-to-point propagation of sound in room acoustics or input-output relationships of linear systems in electroacoustics. Measurements of impulse responses or transfer …
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Tranquillity by design - Architectural and landscape interventions to improve the soundscape quality in urban areas exposed to aircraft noise
… from aircraft negatively impact the quality of life for those in areas around airports. Excess noise levels can cause stress-related complaints, leading to adverse health effects. Although newer aircraft are significantly quieter than older models, aircraft noise pollution remains a problem. …
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Ultrahigh resolution surface phononics
Phonons are one of the most important quasiparticles in condensed matter physics; they influence a wide range of physical properties ranging from thermal and electrical conductivity to the propagation of sound. Phonons are also crucial to emerging research fields such as quantum information and …