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Energy Localization And Heat Generation In Composite Energetic Systems Under High-Frequency Mechanical Excitation, Jesus O. Mares

Open Access Dissertations

In this work, the ability to use high frequency mechanical excitation to generate significant heating within plastic bonded explosives, as well as single energetic particles embedded within a viscoelastic binder, is studied. In this work, the fundamental mechanisms associated with the conversion of high-frequency mechanical excitation to heat as applied to these composite energetic systems are thoroughly investigated.

High-frequency contact excitation has been used to generate a significant amount of heat within samples of PBX 9501 and representative inert mock materials. Surface temperature rises on the order of 10 °C were observed at certain frequencies over a range from 50 …

Experimental Investigation Of A Reacting Transverse Jet In A High Pressure Oscillating Vitiated Crossflow, Christopher Allen Fugger

Open Access Dissertations

Staged combustion is one design approach in a gas turbine engine to reduce pollutant emission levels. In axially staged combustion, portions of the air and fuel are injected downstream of a lean premixed low NOx primary combustion zone. The gas residence time at elevated temperatures is decreased resulting in lower thermal NOx, and the reduced oxygen and high temperature vitiated primary zone flow further help to reduce pollutant emissions and quickly complete combustion.

The Effects Of Random Bottom Bathymetry On Coherence In Shallow Water Acoustic Propagation, Jennifer Leigh Wylie

Open Access Dissertations

In an ideal shallow water propagation channel the sound field is accurately described by normal modes and the mode structure is predictable with clean separated modes. However the real ocean environment is rarely ideal, and variations in bottom bathymetry and water column sound speed are usually present. Random fluctuations of the sound speed in time, space, and/or the boundaries can distort modes such that phase coherence is reduced and under some conditions completely lost. The basic research community seeks to understand the effects of internal waves on temporal coherence. Here the study method of choice is to use fixed system …

Recording And Analysis Of Transient Otoacoustic Emissions During Outer Ear Canal Pressure Compensation, Moises Perez

Open Access Dissertations

Otoacoustic Emissions (OAEs) are sounds generated by an active process in the auditory system’s cochlea. It has been widely accepted that the generation of OAEs is a precursor for healthy hearing. The measurement of evoked OAEs can be used to determine the general health of the cochlea and basilar membrane's response and sound transmission forward and backwards through the inner ear. OAEs are commonly used for newborn infant hearing screening where many middle ear pathologies are first detected. In most cases, secondary screening tests such as tympanometry are not conducted unless the patient has failed the OAE screening first. Increases …

Effects Of Nasalance On The Acoustics Of The Tenor Passaggio And Head Voice, Nicholas Kevin Perna

Open Access Dissertations

PERNA, NICHOLAS (D.M.A., Vocal Pedagogy and Performance) Effects of Nasalance on the Acoustical Properties of the (May 2008) Tenor Passaggio and Head Voice Abstract of a doctoral essay at the University of Miami. Doctoral essay supervised by Professor David Alt and Professor Rachel L. Lebon. No. of pages in text. (73) This study aims to measure the effect that nasality has on the acoustical properties of the tenor passaggio and head voice. Not to be confused with forward resonance, nasality here will be defined as nasalance, the reading of a Nasometer, or the percentage of nasal and oral airflow during …