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 27 for “"acoustic transmission"”.
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Acoustic transmission in the respiratory system
Thesis (Ph. D.)--Harvard University--Massachusetts Institute of Technology MIT Division of Health Sciences and Technology, Program in Medical Engineering and Medical Physics, 1989.
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Frequency dependent acoustic transmission in nonuniform materials
… model for the frequency response of the acoustic power transmitted through nonuniform materials is developed. Using the ideal mixture model to relate acoustic velocity and impedance, this normalized model demonstrates that the power transmission characteristics are completely determined …
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Acoustic transmission through fluid-filled pipes in boreholes
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1991, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1991.
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Implementation of multi-layer active structural-acoustic transmission control
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001.
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The roles of pars flaccida in middle ear acoustic transmission
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.
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statistical analysis of acoustic transmission scintillation in the 2014 Nordic Seas Experiment
The propagation of acoustic signals through an underwater waveguide adds randomness to the received signal, called scintillation. For a fully saturated field, this scintillation features statistical properties that can be measured and estimated. Many analyses were conducted in the past for finding …
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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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Synthesis and characterization of metal-polyaniline thin films and membranes
… by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to investigate the microstructures of specimens. Auger electron spectroscopy (AES) and X- ray photoelectron spectroscopy (XPS) were employed to study the chemical bonding and interactions between deposited …
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Thermomechanical Response of Shape Memory Alloy Hybrid Composites
… post-buckling, vibration, sonic fatigue, and acoustic transmission. A thermomechanical model is presented for analyzing such shape memory alloy hybrid composite (SMAHC) structures exposed to thermal and mechanical loads. Also presented are (1) fabrication procedures for SMAHC specimens, (2) …
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A control problem for Burgers' equation
… supersonic flow about airfoils, traffic flows, acoustic transmission, etc. For high Reynolds number, the open-loop system (no control) produces steep gradients due to the nonlinear nature of the convection. The steep gradients are stabilized by feedback control laws. In this phase, sufficient …
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Scattering Matrix Analysis of Surface Acoustic Wave Reflectors and Transducers
… matrix consisting of one electrical and two acoustic ports. These scattering parameter analytical expressions are functions of material constants, electrode geometry, and frequency. The three port single electrode scattering matrices are acoustically cascaded to produce a three port device …
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Using otoacoustic emissions to measure the transmission matrix of the middle-ear
… an experimental method for measuring the acoustic transmission matrix of the middle-ear using otoacoustic emissions. The experiment builds on previous work that uses distortion product otoacoustic emissions (DPOAEs) as an intracochlear sound source to drive the middle-ear in reverse. This …
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Near-Field Pressure Distributions to Enhance Sound Transmission into Multi-Layer Materials
… significant energy transfer from incident acoustic waves across the air-material interface. Refraction also plays a role in preventing acoustic transmission, as the wave speed difference between air and solid materials results in an increase of the resulting propagation angles, creating …
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Autonomous Underwater Vehicle (AUV) path planning and adaptive on-board routing for adaptive rapid environmental assessment
In shallow water, a large part of underwater acoustic prediction uncertainties are induced by sub-meso-to-small scale oceanographic variabilities. Conventional oceanographic measurements for capturing such ocean-acoustic environmental variabilities face the classical conflict between resolution and …
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Mean, variance, and temporal coherence of the 3D acoustic field forward propagated through random inhomogeneities in continental-shelf and deep ocean waveguides
When an acoustic field propagates through a multimodal waveguide, the effect of variations in medium properties induced by 3D random inhomogeneities accumulates by multiple forward scattering over range. This causes significant random fluctuations in the received field and greatly affects …
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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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A Theoretical and Experimental Investigation into the Spectra of Selected Resonators
An acoustic transmission line system in which the echo returned from a resonator, having an arbitary spectrum of resonances has been analysed. The results show that the system, which is of practical importance because of the separation of the signal transducer and the resonator being studied, can …
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Ocean acoustic uncertainty for submarine applications
… These ocean models can be coupled with acoustic models that account for variations in the ocean environment and complex bathymetry to yield accurate acoustic field representations that are both range and time independent. Utilizing the MIT Multidisciplinary Environmental Assimilation …
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Examining transmission power in minimum capacity underwater acoustic networks
This paper explores the prospect of reducing the transmission power required to operate links within an underwater acoustic network by minimizing the total capacity of the network while maintaining certain data flow requirements. This is motivated by an approximate model for underwater acoustic …
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Nondestructive Detection of Hollow Heart in Potatoes Using Ultrasonics
… with a power level of 0.22 W for the test of acoustic transmission through whole potato tuber in a transverse direction at different locations along the longitudinal axis with a certain interval distance. It was found that the waveform analyses in time domain for a series of transmitted …
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