Theses and Dissertations

This thesis consists of two parts. In the first part a small-scale high-speed monohull boat was fitted with a suspended flap under the bottom. The author tested shock absorbers for this boat, and worked on data analysis from a few initial test runs. The boat tests were performed during a few hours in a single day and the data are far too scarce to draw any conclusions. The second part of the thesis concerns multi-body numerical analysis of a suspension boat that consists of an airborne centerhull and four suspended sponsons. No simulations of boat dynamics in waves were performed.

The electromagnetic properties of a live biological system are extremely important to many medical applications. While information about electromagnetic properties of tissues are available in the literature, little or no data are available for a single cell or subcellular structures. Microwave biological/cell detection has been demonstrated to be useful and promising in many medical applications due to its internal properties such as non-invasive, fast and label-free.

In this study, Stress Intensity Factors are calculated for cracks located at the toe of a fillet weld subjected to residual stresses due to the welding. The welding model used in this study is based on Longitudinal stiffener test specimens. The meshes generated for these models were obtained from the commercial code HYPERMESH. The welding heat transfer simulation and calculation of the welding residual stresses used the explicit FE commercial code SYSWELD.

The objective of this study is to predict the magnitude and spatial variation of the residual stresses in an autogenously welded flat plate. Autogenous welding is a fusion welding process using heat without the addition of filler metal to join two pieces of the same metal. The residual stresses in a flat plate, close to the weld pool, are closely examined in this study. Using the welding simulation program SYSWELD, a 2-D geometric model was constructed using ANSYS 15.0, then meshed with quadratic 2-D elements in Visual-Mesh 10.0.

The Orbital friction welding process utilizes high heat generated at the interface from friction to form a high strength weld. A full transient thermal 3D analysis combined with axial displacement was conducted using ANSYS to simulate this welding process. The goal was to model the process of orbital friction welding by incorporating industry-relevant parameters under realistic boundary conditions. The work illustrates the dependency of the temperature profile on various processing parameters at any point in time in the welding process.

For the first time, the impedance spectrum of live Jurkat T-lymphocytes human cells was characterized in a single sweep spanning six decades of frequency from 9 kHz to 9 GHz. The ultrawide bandwidth bridged the traditional impedance spectroscopy at kilohertz to megahertz frequencies with the recently developed microwave dielectric spectroscopy, which can probe the cell interior without being hindered by the cell membrane.

Residual stresses are generated from the non-linear thermal loading and unloading cycles that occur during a typical multi-pass ARC welding process. Large residual stresses and plastic strains will in turn cause reliability problems closely associated with cracking and distortion in welded structures, which will ultimately reduce the structure's fatigue life. In this study, the particular structure of interest is an outlet manifold fabricated with large circumferential welds.

MEMS (a Microelecticalmechanical device) has an important role in electronic industry. It allows to incorporate the electronic with mechanical system totally within a single chip.

This thesis investigates the fatigue characterization of modern head-hardened rails, with a specific focus on detail (i.e. transverse) fracture. This study provides necessary information to determine a safe and economically viable rail inspection interval.Safe inspection interval has previously been established for legacy, i.e. non-head-hardened rails. The head hardening process, which evolved over the past several decades, has been designed to improve rail wear resistance by increasing hardness.

A closed-loop capacitance sensing and control mix-mode circuit with a dedicated sensor electrode and a proportional-integral controller was designed for MEMS varactors. The control was based on tuning the bias magnitude of the MEMS varactor according to t

Railroads are an essential mode of transportation for people and goods worldwide, and steel rails are a critical component of this infrastructure. However, steel rails are subjected to various forms of loading during their service life, which can lead to the formation and propagation of fatigue cracks, compromising their structural integrity. The presence of subsurface cracks can compromise the structural integrity of the rail and increase the risk of catastrophic failure, such as "detail fracture", which is related to high tensile residual stresses induced during rail manufacturing.