Digital Commons Network^™

Investigation Of Vorticity Confinement As A High Reynolds Number Turbulence Model, Nicholas F. Lynn

Doctoral Dissertations

Vorticity Confinement (VC) is a computational technique used to compute fluid flows with thin vortical regions in an accurate and efficient manner. Recent results have shown that it accurately computes the turbulent wake behind blunt bodies at large Reynolds numbers. Physically, these flows are dominated by thin vortices that convect downstream with the flow, which accounts for the important higher-order velocity statistics. These thin vortices are artificially dissipated with traditional methods, whereas VC can accurately compute them.

VC consists of a set of discrete equations with the confinement appearing as a source term in the discretized momentum equations. The term …

Novel Numerical Approaches For The Resolution Of Direct And Inverse Heat Transfer Problems, Gregory Evan Osborne

Doctoral Dissertations

This dissertation describes an innovative and robust global time approach which has been developed for the resolution of direct and inverse problems, specifically in the disciplines of radiation and conduction heat transfer.

Direct problems are generally well-posed and readily lend themselves to standard and well-defined mathematical solution techniques. Inverse problems differ in the fact that they tend to be ill-posed in the sense of Hadamard, i.e., small perturbations in the input data can produce large variations and instabilities in the output. The stability problem is exacerbated by the use of discrete experimental data which may be subject to substantial measurement …

Development Of An Integrated Opto-Electric Biosensor To Dynamically Examine Cytometric Proliferation And Cytotoxicity, Chang Kyoung Choi

Doctoral Dissertations

My doctoral research has focused on the development of microscale optical techniques for examining micro/bio fluidics. Preliminary work measured the velocity field in a microchannel, by optical slicing, using Confocal Laser Scanning Microscopy (CLSM). Next, Optical Serial Sectioning Microscopy (OSSM) was applied to examine thermometry by detecting the free Brownian motion of nano-particles suspended in mediums at different temperatures. An extension of this work used objective-based Total Internal Reflection Fluorescence Microscopy (TIRFM) to examine the hindered Brownian motion of nano-particles that were very close to a solid surface (within 1 mm).

An optically transparent and electrically conductive Indium Tin Oxide …

Analysis And Optimization Of Partial Length, Constrained Damping Layers, Shing-Jia Tang

Doctoral Dissertations

A laminated beam with constrained damping layers is analyzed. The normal strain in the longitudinal direction and shear strain in the viscoelastic layer is considered. Hamilton’s principle is used to derive equations of motion and boundary conditions. A 6th order equation is used to describe the portion of the beam covered with a constrained damping layer and a 4th order equation is used to describe the remainder of the beam. The characteristic equations are solved numerically with a gradient-based optimization method in order to determine normalized loss factor values. The loss parameter (normalized loss factor) is shown to be a …

Modeling Coordinate Measuring Machine Scanning Operations, Pamela Murray Moor

Doctoral Dissertations

International standards require that dimensional inspection operations include an assessment of measurement uncertainty. Scanning coordinate measuring machines (CMMs) are frequently used to measure part surfaces and features, and there is a continuing need to improve their performance for high precision measurement applications. This research provides a mechanism for minimizing the uncertainty of measurements made with a CMM in scanning mode by developing a model of CMM scanning that allows selection of optimum scanning parameters.

The method for selecting scanning parameters is based on models developed from measurements of a ring with a constant five micrometer amplitude swept sine wave machined …