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Physical Sciences and Mathematics Commons

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Full-Text Articles in Physical Sciences and Mathematics

Nondestructive Evaluation Of Aircraft Composites Using Terahertz Time Domain Spectroscopy, Christopher D. Stoik Dec 2008

Nondestructive Evaluation Of Aircraft Composites Using Terahertz Time Domain Spectroscopy, Christopher D. Stoik

Theses and Dissertations

Terahertz (THz) time domain spectroscopy (TDS) was assessed as a nondestructive evaluation technique for aircraft composites. Material properties of glass fiber composite were measured using both transmission and reflection configuration. The interaction of THz with a glass fiber composite was then analyzed, including the effects of scattering, absorption, and the index of refraction, as well as effective medium approximations. THz TDS, in both transmission and reflection configuration, was used to study composite damage, including voids, delaminations, mechanical damage, and heat damage. Measurement of the material properties on samples with localized heat damage showed that burning did not change the refractive …


Comparative Kinetics And Distribution To Target Tissues Of Organophosphates Using Physiologically-Based Pharmacokinetic Modeling, Rick E. Vermillion Mar 2008

Comparative Kinetics And Distribution To Target Tissues Of Organophosphates Using Physiologically-Based Pharmacokinetic Modeling, Rick E. Vermillion

Theses and Dissertations

A physiologically-based pharmacokinetic model has been developed to examine the effects of organophosphates on the levels of acetylcholine in different tissues throughout the mammalian body. Many organophosphate-like chemical and kinetic characteristics are tested without reference to a specific chemical. Characteristics include partition coefficients, metabolic constants, the inhibition coefficient, the aging rate, and the regeneration rate. Two separate exposure scenarios are tested and compared against a baseline. The baseline consists of a direct inhalation exposure. The first exposure scenario examines the effects of bronchial scrubbing (via inhalation) and the second scenario is a study of dermal exposures and compares the levels …


Oxygenation Of The Root Zone And Tce Remediation: A Plant Model Of Rhizosphere Dynamics, Ian F. Thompson Mar 2008

Oxygenation Of The Root Zone And Tce Remediation: A Plant Model Of Rhizosphere Dynamics, Ian F. Thompson

Theses and Dissertations

This study analyzes rhizosphere conditions that enhance the effective aerobic degradation of TCE in wetland bioremediation systems. A plant model was built using Stella 9.0 modeling software and uses numerical integration evaluation; it addresses movement of oxygen through plant vascular and aerenchymal systems, and into the rhizosphere where oxygen and other substrates influence bacteria. Methanotrophs and heterotrophs are assumed to be influential bacteria groups. Variations of humidity-induced-convection, methane, soil carbon, and copper concentrations are evaluated. Varying concentrations and hydraulic loadings of TCE are assessed with respect to TCE consumption rate and TCE treatment efficiency. Soil conditions most directly affected TCE …