Theses

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  • 10-GHz wide tuning-range linear voltage-controlled oscillator
    10-GHz wide tuning-range linear voltage-controlled oscillator
    The current high-growth nature of digital communications demands higher speed serial communication circuits. Present day technologies barely manage to keep up with this demand, and new techniques are required to ensure that serial communication can continnue to expand and grow. The goal of this work is to optimize the performance of an essential building block of serial communication circuits, namely, the phase-locked loop (PLL), so that it can cope with today's high-speed communication. Due to its popularity, the optimization has targeted the charge-pump-based implementqation of the phase-locked loop. This goal is achieved by researching, designing, and evaluating high speed serial communication circuits. Research has involved an in-depth study of the state of the art in high-speed serial communication circuits ; high-speed, controlled oscillators, and CMOS technology. An LC, voltage-controlled oscillator (VCO) is designed in 0.18-micron, mixed-signal, 6-metal-2-poly, CMOS process. A novel tuning technique is employed to tune its output frequency. Simulation results shows that it provides quadrature and differential outputs, operates with 10 GHz center frequency, 600-MHz tuning range centered around its center frequency, and phase noise of -95 dBc/Hz at 1-MHz offset from the fundamental harmonic of its output, and draws 10 ,A of DC current from a single 1.8-V power supply. Also, it exhibits a good linearity throughout its tuning range. The new tuning technique increases the tuning range of the VCO to 6% of its center frequency compared to the 1-to-2% typical value. As its locking performance depends on the characteristic of the employed VCO and to demonstrate the effect of optimizing the tuning range of the VCO, a charge-pump PLL is designed. Simulation results shows that the PLL acquisition range is 300 MHz compared to a maximum value of 100 MHz when a conventional LC VCO is employed. Also, as a measure of its tracking range, the maximum frequency slew rate of its input has improved by 40%.
    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.
    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.
    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.
    3D modelling of industrial piping systems using digital photogrammetry and laser scanning
    3D modelling of industrial piping systems using digital photogrammetry and laser scanning
    Industrial metrology is one of the fastest growing areas in advanced technologies, such as electronics and optics, computation speed, and it has been increased in recent years. There are several tools used in industrial metrology, such as total stations, digital photogrammetry, and laser scanning. Close range digital photogrammetry has been implemented for an industrial piping system in terms of installation, inspection, and replacement. Laser scanning is also used for industrial measurements to generate 3D coordinates points. In order to develop a 3D modelling strategy, this thesis focuses on the development, selection and design of photogrammetric procedures and project specific targets. This thesis also explores image-acquiring sensors such as digital cameras and laser scanners in terms of their capabilities and advantages. Based on experimental setup accuracy, measurements of piping systems are compared for applications of two different sensors.Effects of different surface materials are examined in laser scanning applications and several different types of materials are used for acquiring point clouds data. Measurement of pipes' diameters and residual analyses are conducted with different surface materials, which are used for industrial pipes. Significant improvement in laser scanning data acquisition is examined in terms of data quality both quantitatively and qualitatively during the residual analyses.
    3D printed phantom to mimic dynamic softening of cervix during pre-labour
    3D printed phantom to mimic dynamic softening of cervix during pre-labour
    It is thought that through the development of more realistic training models for midwives and obstetricians it may be possible to reduce the overuse of labour induction. To this end we demonstrate a method for creating pneumatically-controlled phantom cervixes using thermoplastic elastomer, filled with a granular material. The maximum spring constant of the phantom cervix was measured to be 10.5 N/m at -20 kPa deflated air (vacuum) and the minimum spring constant measured was 5.3 N/m at 20 kPa inflated air. The true stress measured on these elastomeric phantom cervixes indicated a maximum stress of 133 kPa and a minimum stress of 94 kPa at 0.15 strain. Discrimination and threshold tests demonstrated that people can distinguish between the hard and soft states of the phantom. Future work will focus on increasing the softness of these devices.