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 37 for “"Physics, Acoustics"”.
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Design of interactive maps for ocean dynamics data
… and predicting diverse ocean dynamics, including physics, acoustics, and biology on varied scales, thereby developing new methods for multi-resolution ocean prediction and analysis, including data generation and assimilation. The group has primarily used non-interactive ocean plots to visualize …
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Statistical Properties of Transmission Spectra of Ergodic Wave Billiards: Random Hamiltonian Approach
Finally, we considered the experimental realization of the RMT system. We examined the dissipation of diffuse ultrasonic energy in a reverberant body coupled to a waveguide, i.e. in an open ergodic system. A simple model predicts a Porter-Thomas-like distribution of level widths and corresponding …
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Evaluating the Benefit of Recorded Early Reflections From a *Classroom for Speech Intelligibility
Recent standards for classrooms acoustics recommend achieving low levels of reverberation to provide suitable conditions for speech communication (ANSI, 2002; ASHA, 1995). Another viewpoint recommends optimizing classroom acoustics to emphasize early reflections and reduce later arriving …
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Mechanoluminescence and Sonoluminescence From Acoustic Cavitation
The effect of single-bubble sonoluminescence (SBSL) intensity and spectral profile from the addition of low concentrations of organics to sulfuric acid has been investigated. It was found that the addition of small quantities of organics to sulfuric acid greatly reduced the total SBSL intensity. …
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The Reassigned Bandwidth-Enhanced Method of Additive Synthesis
We introduce a highly manipulable, high fidelity additive sound model capable of representing transient sounds and sounds having significant nonsinusoidal energy. We represent sounds as a collection of bandwidth-enhanced partials having sinusoidal and noise-like characteristics. Partials are …
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Acoustic Coherence Imaging Through the Atmosphere
"The imaging of acoustic ""scenes"" through the atmosphere is a subject with little treatment in the literature. This thesis strives to set the state of the art in this field by presenting imaging methods and their performance in the turbulent atmosphere. Both narrowband interferometry and wideband …
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Plane -Wave Time -Domain Algorithms for Efficient Analysis of Three-Dimensional Transient Wave Phenomena
… of paramount importance in such disciplines as acoustics, electromagnetics, and geophysics. Numerical techniques to perform such simulations call for the evaluation of retarded-time boundary integrals (RTBIs) as these boundary integrals play a fundamental role in formulation of the integral …
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Articulatory Speech Synthesis and Speech Production Modelling
Based on our dissertation work, we carefully argue that the articulatory speech production model has the potential to flexibly synthesize natural-quality speech sounds and to provide a compact computational model for speech production that can be beneficial to a wide range of areas in speech signal …
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Measurement of the Nonlinearity Parameter B/a in Biological Materials Using the Finite Amplitude and Thermodynamic Method
It is well-known that materials exhibit a decrease in compressibility when subjected to high compression. This decrease in compressibility may be described by the nonlinearity parameter B/A. Organic liquids have been shown to possess a wide variation of the parameter, ranging from 5 to 12. This …
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Investigation of the Acoustics of Plucked String Tones Based on the Analysis of Their Time-Varying Spectra
This research investigates two aspects of the time-varying vibration patterns of plucked string tones of classical guitar, Chinese pipa and Chinese ch'in. First, the assumption that horizontal and vertical frequencies and decay rates may be different is used as a basis for classifying the partial …
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Numerical and Laboratory Studies of Ultrasonic Anderson Localization
A numerical study of Anderson localization in two dimensions and a laboratory study of weak localization in three dimensions are presented. The two-dimensional study was performed by mathematically modelling a system of masses connected to a rigid base by springs of random stiffness. The masses …
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An Investigation of the Multiple Scattering of Waves in Two-Dimensional Random Media
Numerical studies of the ensemble average, or coherent, wave in a two-dimensional random medium have been undertaken for the steady-state and transient cases. The medium consisted of a tensioned mesh with a uniform distribution of point masses attached at the intersection points of the mesh. For …
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The Absorption of Ultrasound in Aqueous Solutions of Bovine Serum Albuminand Polyethylene Glycol
Made available in DSpace on 2014-12-08T22:24:31Z (GMT). No. of bitstreams: 1 6910746.pdf: 4622657 bytes, checksum: 87dd37a615b14489403204202a3686d6 (MD5) Previous issue date: 1968
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Scattering from imperfect interfaces
Scattering from an imperfect planar interface between two different elastic media was studied to examine how the signals induced at the transducers by reflected, transmitted and scattered waves are related to the interface properties. Also, the effect of anisotropy on scattering was assessed by …
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Asymptotic description of the acoustic microscopy of a surface-breaking crack
An asymptotic description of the acoustic signature of a crack, breaking the surface of an otherwise homogeneous, isotropic elastic material, determined using either a line focus or a point focus scanning acoustic microscope is constructed. The incident focused beam is constructed as a Fourier …
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Stochastic Dynamically Orthogonal Modeling and Bayesian Learning for Underwater Acoustic Propagation
… data, as well as to the complex ocean physics and acoustics dynamics, multiscale interactions, and large dimensions. There are thus several sources of uncertainty in acoustic predictions. They include the ocean current, temperature, salinity, pressure, density, and sound speed fields, …
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Development and applications of hypersingular boundary integral equations for three-dimensional acoustics and elastodynamics
The boundary integral equation/boundary element method (BIE/BEM) has emerged as a powerful alternative tool to other numerical methods for many problems in engineering. The hypersingular BIE's, which are derivatives of conventional BIE's, are indispensable for the analyses of many problems in …
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Analyses and predictions of ultrasound interactions with model biomembrane systems via two-state transition model
Low intensity ultrasound (approximately 10$\sp{-6}$ W/cm$\sp2$) in the frequency range of 0.5 MHz to 5.0 MHz was employed to investigate biomembrane structural relaxation kinetics via absorption and velocity dispersion spectroscopy. The multilamellar vesicles utilized in this investigation were …
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Aspiration in Chinese
This dissertation studies aspiration in Chinese in these four areas: the temporal relationships between aspiration and the vowel of the syllable, the perception of aspiration, the correlation between pitch and aspiration, and the role of aspiration in a historical change in Chinese. Data based on …
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A finite difference numerical model for the propagation of finite amplitude acoustical blast waves outdoors over hard and porous surfaces
This study has concerned the propagation of finite amplitude, i.e. weakly non-linear, acoustical blast waves from explosions over hard and porous media models of outdoor ground surfaces. The nonlinear acoustic propagation effects require a numerical solution in the time domain. To model a porous …
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