Theses

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  • 2-D Kasai velocity estimation for Doppler optical coherence tomography / by Darren Morofke.
    2-D Kasai velocity estimation for Doppler optical coherence tomography / by Darren Morofke.
    Optical Coherence Tomography (OCT) is a high-resolution, non-invasive technique to image subsurface tissue and tissue functions. A broadband light source illuminates an object and the reflected photons are processed using an interferometer, demodulated into inphase and quadrature components and then digitized. The captured data contains information about the velocity of the moving scatterers but current Doppler estimation algorithms have a limited velocity detection range. Here we demonstrate Doppler OCT (DOCT) detection of in vivo of blood flow in a rat aorta with over 1 m/s peak velocity through an esophageal DOCT probe using a new processing technique. Previous methods have used a transverse Kasai (TK) autocorrelation estimation to estimate the velocity. By calculating the Kasai autocorrelation with a lag in the depth or axial direction, backscattered frequency information is obtained. Through subtraction with stationary backscattered information, the Doppler shift is obtained by the axial Kasai (AK) technique. Maximum non-aliased Doppler frequency estimation using a time domain DOCT system increased from +/-4 kHz to =+/-1.6 MHz. The TK has better velocity resolution in the low flow rate range and when combined with the AK we demonstrate a dynamic frequency range over 100 dB with a velocity detection range from 10 [micro]m/s to over 1 m/s. This velocity range spans from microcirculation to cardiac blood flow velocities.
    2D electromagnetic actuated quasi-static FPCB based micromirror for laser marking/engraving system
    2D electromagnetic actuated quasi-static FPCB based micromirror for laser marking/engraving system
    This thesis presents the design and development of quasi-static 2-dimensional Flexible Printed Circuit Board (FPCB) based micromirror for portable laser marking/ engraving system. It focuses on the modelling and prototyping of the novel 2-dimensional electromagnetic actuated micromirror which can be used in place of two 1-dimensional micromirrors having the benefits of lower footprint in size of the scanner and efficient alignment with the incident laser beam. This 2-dimensional micromirror can be used in portable low power laser marking/ engraving system ideally designed for consumer applications like printing name cards, engraving jewellery etc. The problem of drifting/ creep associated with quasi-static mode of FPCB based micromirror actuators is analyzed and Zero method is proposed to minimize the drifting issue which is proven experimentally in the thesis. From this thesis work, it is evident that the developed 2-dimensional, low-cost, quasi-static FPCB based micromirror would be a suitable candidate for replacement of the expensive conventional MEMS bonded mirrors in the market.
    3 Minutes to Midnight:  speculative game design for nuclear disarmament
    3 Minutes to Midnight: speculative game design for nuclear disarmament
    This paper proposes a digital game concept designed to increase the millennial generation’s level of engagement with the campaign for nuclear disarmament. It discusses four key research findings that support the need for the development of this game, and provides helpful information to enable better understanding of the relatively specialized inspiring concepts. The paper argues that activist campaigns should design nuanced communication plans that consider the complexities of the issue and leverage the digital media tools whose affordances best match the goals of the campaign. In the case of nuclear disarmament, I propose a campaign communication strategy in the form of a pervasive social impact game, called 3 Minutes to Midnight, as an effective way to ignite widespread public support in the 21st century.
    3-D Fibrous Network of TiO2 Nanoparticles: Raman Sensor Development
    3-D Fibrous Network of TiO2 Nanoparticles: Raman Sensor Development
    A 3-D nano-fiber particle network of TiO2 nanoparticles is synthesized by pulsed femtosecond laser irradiation of a pure Ti substrate. This study investigated the properties of the resulting nanostructure for chemical and biomolecular detection by Raman spectroscopy. Controlled tuning of surface roughness, porosity and depth of the 3-D network were found to directly influence Raman detection. The presented findings support a previously unrealized detection capacity by TiO2. Crystal violet was used to test the Surface-Enhanced Raman Spectroscopy (SERS) performance of the developed TiO2 sensor pads. The corresponding Raman enhancement factor was determined to be 1.3x106 which is directly comparable to commercial Ag and Au based Raman substrates. Bisphenol-A and diclofenac sodium salt were introduced into drinking water and tested with various sensor pads to develop a Raman detection map. The results suggest an affinity towards uniform TiO2 3-D nanofibrous networks.
    3-D finite element analysis of laterally loaded short shafts in soil
    3-D finite element analysis of laterally loaded short shafts in soil
    The objective of this research is to conduct an optimized design of drilled shaft foundation for noise barrier walls. A non-linear three-dimensional (3D) finite element method (FEM) program, Plaxis 3D, is used to investigate the behaviour of laterally loaded shafts. Two published cases are used to calibrate the modelling method and validate the numerical results. In the case of a field test performed by Helmers (1997), FEM results agree very well with field tests in terms of ultimate load and deflection curves. In the laboratory test conducted by Uncuoglu & Laman (2011) case, numerical results agree well with their results except the soil-shaft interface modelling part. The Plaxis 3D embedded pile model tends to overestimate the lateral load capacity of a smooth pile. Though it is satisfactory in modelling a pile with a “rough” surface. Two theoretical formulas in estimating lateral capacity of piles are also compared with the FEM results. It is found that Broms’s (1964b) theory for cohesionless soils has underestimated the lateral load capacities and Brinch-Hansen’s (1961) theory provides a more accurate estimation. In summary, 3-D FEM is able to accurately simulate the behaviour of laterally loaded drilled shafts in soil.
    3-D modeling and simulation of crystal growth of GE₀.₉₈ Si₀.₀₂ under the influence of various gravity levels, G-jitter and rotating magnetic field using traveling solvent method
    3-D modeling and simulation of crystal growth of GE₀.₉₈ Si₀.₀₂ under the influence of various gravity levels, G-jitter and rotating magnetic field using traveling solvent method
    A three-dimensional numerical simulation was conducted to study the effect of a rotating magnetic (RMF) field on the fluid flow, heat transfer and mass transfer in the presence of various gravity levels by utilizing the traveling solvent method (TSM). The presence of the RMF suppressed the buoyancy convection in the GE₀.₉₈ Si₀.₀₂ solution zone in order to get homogeneity with a flat growth interface. It was found that the intensity of the flow at the centre of the crucible decreased at a faster rate compared to the flow near the walls when increasing magnetic field intensity is combined with a certain rotational speed. This behavior created a stable and uniform silicon distribution in the horizontal plane near the growth interface in the terrestrial condition. Different magnetic field intensities for different rotational speeds were examined in both terrestrial and micro-gravity conditions. The effects of residual acceleration, known as G-jitter, on board the International Space Station and European Space Orbiter were also investigated.
    3-DOF Longitudinal Flight Simulation Modeling And Design Using MATLAB/SIMULINK
    3-DOF Longitudinal Flight Simulation Modeling And Design Using MATLAB/SIMULINK
    Flight simulators are widely used in aerospace industry for multiple purposes. This paper highlights the importance of engineering flight simulators and presents a 3 degrees-of-freedom longitudinal flight simulation model that can be adopted to simulate aircraft behaviour for engineering analysis. A brief overview of aircraft design process is presented with reference to flight simulation procedure. A special emphasis is placed on Massachusetts Institute of Technology's Athena Vortex Lattice program that can be used to calculate aerodynamic characteristics for a given geometric configuration. The paper explains modeling of aerodynamics and thrust blocks and shows how they can be linked with equations of motion block to build a comprehensive flight simulation model. Matlab script that linearizes and trims equations of motion is also discussed and key stability results are explained in detail. Simulation test cases are also presented. Several recommendations are made at the end of the paper on the potential use of simulators and also on ways of improving the simulation model.
    3.3V Transmitter Using 1.8V Transistors In A Cascode Configuration
    3.3V Transmitter Using 1.8V Transistors In A Cascode Configuration
    A voltage-mode transmitter using a 1.8V-to-3.3V levelshifter and cascoded output buffer is proposed. 1.8V TSMC 65nm transistors are used. The design is targeted to meet JEDEC Interface Standard for Nominal 3 V/3.3 V Supply Digital Integrated Circuits DC Specifications as well as an AC transmission rate of 200 MHz on a 30 cm 50Ω board trace terminated with a 4 pF capacitive load. Overstress voltages will not be exceeded in order to avoid device failure due to breaching Gate Oxide Integrity, Hot Carrier Injection, or Negative Bias Temperature Instability.
    35% Carbon Dioxide Reactivity In A Bulimia Nervosa Sample
    35% Carbon Dioxide Reactivity In A Bulimia Nervosa Sample
    This study extended research on the specificity of the effects of the carbon dioxide (CO₂) challenge by examining panic reactivity in participants with bulimia nervosa (BN) (n=15) compared to those without bulimia nervosa (n=31). All participants completed self-report measures assessing state and trait anxiety, depression, anxiety sensitivity (AS), distress tolerance (DT), discomfort intolerance (DI), and eating disorder features. They subsequently breathed two vital capacity inhalations; room air and 35% CO₂-enriched air. Reactivity to room air was not different between groups. However, participants with BN displayed greater reactivity to CO₂ compared to the participants with BN. AS, DI, and DT could not be tested as potential mediators in the association between diagnostic group and reactivity because these constructs were not associated with reactivity. Eating disorder features and frequency of binges and purges were also not associated with reactivity. Detailed implications and suggestions for further research are discussed.
    360-­Degree Video Journalism: an analysis of the different angles of modern technology and news reporting
    360-­Degree Video Journalism: an analysis of the different angles of modern technology and news reporting
    This paper will analyse and consider 360-­degree videos in the context of previous new technologies and how they changed processes for journalism. Referencing previous research literature, news articles, case studies and my personal experience using 360-­degree videos as a videojournalist, this paper will serve as a conceptual review in order to better understand new considerations that might have to be taken when considering 360-­degree videos for daily news production. Moreover, this paper will review the introduction of liveblogs and Facebook Live, and how each has fundamentally changed journalism. By doing so, this conceptual review will hope to identify unique challenges and successes that 360-­degree video journalism might have for the reporter from a technical, ethical and storytelling point of view.
    3D Reconstruction of Exposed Underground Utilities Using Photogrammetric Methods
    3D Reconstruction of Exposed Underground Utilities Using Photogrammetric Methods
    This thesis addresses the topic of three-dimensional (3D) reconstruction of exposed underground utilities using photogrammetric methods. Research on this topic is mainly motivated by the need for improved information on the location of underground utilities and, thus, to provide reliable information for the management of buried assets. In this thesis, a system of photogrammetric software programs is developed for 3D reconstruction of underground utilities. Camera calibration programs are used for computing interior elements and lens distortion coefficients of digital cameras and saving them in a lookup table (LUT). The accuracy of calibrated image coordinates satisfies the photogrammetric processing demand. An automatic image point detection method is proposed and achieved in these programs. External orientation programs are used for calculating exterior elements of the digital images. Based on geographic information system (GIS) and global positioning system (GPS) techniques, a new ground control points (GCPs) collection method is proposed and implemented in these programs. A 3D reconstruction program provides corresponding functions to obtain and edit 3D information of underground utilities. Epipolar lines are employed as an assisting tool that helps operators easily find homologous points from different digital images. The study results indicate that photogrammetric methods for reconstructing 3D information of underground utilities are effective and low cost.