VictorJuiz/thesis huggingface dataset:
Knowledge and Practices of Family and Emergency Physicians in Managing Non-traumatic Dental Conditions: a Case-based Survey
Keywords: Antibiotics
Dental conditions
Knowledge
Ontario
Physicians
Practices

Background: Physicians are often patients’ first point of contact for management of non-traumatic dental conditions (NTDCs). Objective: To evaluate the knowledge and practices of Ontario physicians in managing NTDCs. Methods: A scenario-based online survey was distributed to Ontario family and emergency physicians (n = 1012). Descriptive and logistic regression analyses were performed. Results: 204 surveys were completed (20.2% response rate). A majority of the sampled physicians would prescribe antibiotics for NTDC scenarios in which an antibiotic would not be indicated. Antibiotic overprescribing was significantly associated with practicing in smaller communities and with patient pressures. About half of the sample (52.9%) felt discomfort in overall management of NTDCs, while 85.3% felt that their training inadequately prepared them to manage NTDCs. Conclusions: Ontario physicians report NTDC management practices that are not in line with “best evidence” care. Areas that present opportunities for improvement in the physician management of NTDCs have been identified.
A Sampling-based Approach to GPGPU Performance Auto-tuning
Keywords: Auto-tuning
GPGPU
Regression Trees

We present a novel strategy for automatic performance tuning of GPU programs. The strategy combines heuristic search with regression trees, a machine learning model, to prune the optimization space. It samples configurations in the space as training data for a regression tree. It then focuses the search on the tree region with the best mean sample performance. Additional regression trees are built using the cumulative samples collected. This process is repeated until the given time budget is exhausted.We implement our strategy in OpenTuner, an open source automatic tuning framework. We evaluate the strategy using 8 benchmark GPU programs run on an Nvidia GTX 1060 GPU. We compare the effectiveness of our strategy in obtaining good performing configurations against the state-of-the-art AUC-Bandit strategy used by OpenTuner. Experimental results show that our strategy is more consistently able to obtain better performing configurations compared to OpenTunerâ s strategy, by up to 34% averaged over 100 auto-tuning experiments.
Novel Approaches to Automated Digital Design Debugging in a Modern Development Cycle
Keywords: Debugging
Machine Learning
Verification

The ever-increasing complexity of modern digital designs has introduced significant challenges to ensuring designs meet specification. Verification alone consumes up to 70% of the cost of designing a chip, with debugging comprising the majority of this cost. In recent years, advances in automated debugging techniques have alleviated this cost, but nevertheless are resource-intensive and offer only design-centric results. This thesis proposes two novel methodologies to address these problems. First, a dual-window approach to analyzing memory-locked errors is introduced. A sliding window is used to model inputs to memory while a fixed observation window is used to model memory outputs. Next, an extensible perceptron-based framework that ranks revisions based on their likelihood of having introduced an error is discussed. A perceptron is trained on past failures and their fixes, then used to make predictions on future failures. Experiments demonstrate the benefits offered by the proposed techniques.
Distinct Oral Neutrophil Subsets Define Health and Disease States
Keywords: CD Markers
Chronic Periodontitis
Neutrophils
Phenotypes

Neutrophils exit the vasculature and swarm to sites of inflammation and infection. Neutrophils are also actively recruited to the healthy periodontium without eliciting clinical signs of inflammation, suggesting a unique immune surveillance neutrophil function. We hypothesized that oral neutrophils in the healthy periodontium exist in a â para-inflammatoryâ state that allows neutrophils to symbiotically interact with the commensal oral microflora. Using the principles of immunophenotyping, we identified four distinct neutrophil subsets: resting circulatory neutrophils, two para-inflammatory and one pro-inflammatory tissue neutrophil phenotypes in the absence and presence of chronic inflammation, respectively. This work is the first to comprehensively characterize healthy oral neutrophils and identity the para-inflammatory neutrophil phenotype, thereby demonstrating that not all neutrophils trafficking through periodontium are fully activated. In addition to establishing possible diagnostic and treatment monitoring biomarkers, the oral tissue neutrophil phenotype model builds on existing literature suggesting that the healthy periodontium may be in a para-inflammatory state.
Development of a Miniature Low Power Cylindrical Hall Thruster for Microsatellites
Keywords: Electric Propulsion
Hall Thruster
Microsatellite
Plasma

To enable more advanced commercial microsatellite missions, a low power electric propulsion system was designed by the University of Toronto Space Flight Laboratory. A prototype cylindrical Hall thruster was first developed using electromagnets. The thruster's performance was evaluated over a range of 20-300 W. At the nominal 200 W operation, 6.2 mN of thrust with a specific impulse of 1139 s was measured with xenon propellant. Significant erosion of the thruster's discharge chamber wall was observed which limited its lifetime to 100 hours. Subsequently, a flight representative version of the thruster was developed. Permanent magnets were used to reduce the size, mass, and power consumption. Changes to the design were implemented to improve lifetime. Performance characterization and literature suggest that a reduction in performance is expected with the use of permanent magnets. Lastly, thermal vacuum and vibration tests were performed to bring the thruster to Technology Readiness Level 6.
Design and Validation of a Transfemoral Amputee Walking Model with Passive Prosthesis Swing Phase Control
Keywords: above knee amputation
computational modelling
prosthetic knee joint
swing phase
swing phase controller
variable walking speeds

A two dimensional, seven segment biped transfemoral amputee swing phase model was developed at four walking speeds as an evaluation tool for variable cadence swing phase controllers. Torques at each joint were modelled as a function of tracking error and a forward dynamic optimization was performed to produce joint torques to match four sets of reference amputee kinematics. A prosthetic knee’s swing phase was simulated across four speeds (0.5, 1, 1.5, 2 m/s) and compared to experimental data. The knee performance RMSE ranged from 1.42° - 37° with increasing errors at higher walking speeds. The introduction of absolute hip motion measured from the affected side increased errors across all walking speeds. Additional modelling and optimization strategies to improve the model’s accuracy are discussed.
Quadrotor Visual Servoing for Automatic Landing
Keywords: IBVS
PBVS
Quadrotor
Visual Servoing

This thesis investigates the application of camera-based tracking and landing for multirotor UAVs on a moving target. Both Position-Based and Image-Based Visual Servoing are utilized to provide guidance to the quadrotor which will aim to track the target and to land on top of it. A novel Image-Based Visual Servoing scheme with a non-static desired image is developed to facilitate landing and yawing motions by the quadrotor. These control laws are then investigated through simulation and implementation on an experimental platform. Experiments are performed using the Ardrone 2.0 quadrotor and a Create Roomba as the ground rover. Successful implementations for landing are presented in the case of the Position-Based Visual Servoing, while hover and small motions are performed using the Image-Based Visual Servoing.
Photoacoustic Imaging for Characterizing Blood Clots and Demyelinated Structures in the Brain
Keywords: Imaging
Photoacoustic
Photothrombosis

Photoacoustic imaging(PAI) is a relatively new imaging modality with high spatio-temporal resolution, suitable for functional imaging. This work examines the potential of PAI for studying diseases within the brain such as stroke and multiple sclerosis. Blood samples imaged on two different photoacoustic systems were analysed though statistical measures in gray level co-occurrence matrix(GLCM), allowing for the classification of clotted and unclotted blood with high sensitivity and specificity (>95%). Using chromophore spectral demixing, lipid-rich myelin was mapped and examined in rodent models of demyelination. We demonstrated focal oxygen deprivation associated with a rodent model of photothrombotic stroke. GLCM statistics independently showed characteristics of blood clotting in these hypoxic regions. Our results support PAI as an investigative tool for studying rodent models of stroke and MS.
Conjugate Heat Transfer and Sooting Propensity of Ethanol for Laminar Coflow Diffusion Flames at Elevated Pressures
Keywords: Combustion
Computational Fluid Dynamics (CFD)
Emissions
Laminar Flame Speed
Soot
Temperature

The effect of sooting propensity of various compositions of methane and ethanol fuel in laminar diffusion flames at elevated pressures was analyzed numerically. Simulations of laminar diffusion flames comprised of pressure conditions up to 20 atm and composition of ethanol and methane fuel ranging from pure methane to pure ethanol. For all fuel compositions evaluated, the total carbon mass flow rate was maintained at a constant value of 0.458 mg/s. Soot formation and soot yield were corroborated against measured data and demonstrated well agreement with trends for pressure and fuel composition. For elevated pressure, fuel compositions with higher ethanol content yield higher peak soot concentrations, however at lower pressures synergistic effects result to soot concentration decreasing with ethanol content for ethanol dominant fuel mixtures. Finally, the effect of conjugate heat transfer and modification in burner wall geometry were evaluated which exhibited improved trends and overall results.
Electromagnetic Actuation for a Dragonfly Inspired Flapping-Wing Micro Aerial Vehicle
Keywords: Dragonfly
Microaerial Vehicles

Insect-scale microaerial vehicles is an area within microaerial vehicles which has seen recent growth due to new understandings of insect flight and the availability of new actuation technologies. Prominent flapping wing MAVs were surveyed and relevant observations taken to help guide the project. Alternative actuation technologies for the UTIAS Robotic Dragonfly project were assessed and an electromagnetic actuator was selected. A new design incorporating this actuator was fabricated was fabricated and tested. The platform features a sub-gram at-scale prototype with independently driven wings, a mass of 222 mg and a wingspan of 75 mm. Experiments demonstrated that the prototype was capable of generating up to 1.34 mN of lift.
Effect of Freestream Turbulence on Laminar Separation Bubbles and Flow Transition on a Low Reynolds Number Airfoil
Keywords: Freestream Turbulence Effects
Laminar Separation Bubbles
Low Reynolds Airfoil

The effect of freestream turbulence intensity on the laminar separation bubble and flow transition over an SD7003 airfoil was investigated. Measurements were performed for Reynolds numbers ranging from 60,000 to 250,000, various angles of attack and turbulence intensities between 0.05% and 0.99%. Boundary layers with a separation bubble were found to develop a turbulent boundary layer more rapidly than those without. The trends in the skin friction downstream of the peak corresponding to the development of a turbulent boundary layer were very similar for all turbulence intensities, suggesting the turbulent boundary layer forming downstream of transition was not significantly affected by the turbulence intensities investigated. The fluctuating velocity spectra showed that the increase in freestream turbulence intensity introduced sufficient energy to the laminar boundary layer to initiate transition before the flow was able to separate at an angle of attack of 4â Ś but not at 8â Ś.
Fourteen-Moment Maximum-Entropy-Inspired Closures for Non-Equilibrium Gases and Liquid Sprays
Keywords: Liquid Sprays
Maximum Entropy
Moment Closures
Non-Equilibrium Flows
Rarefied Gas Dynamics

With the purpose of developing a model able to evaluate transition regime rarefied gas dynamics and disperse liquid spray flows, a novel closed-form bi-Gaussian closure to the 14-moment member of Levermore's maximum-entropy hierarchy is derived and evaluated. A thorough evaluation of its univariate kinetic equivalent, namely the bi-Maxwellian closure, is first performed in the context of a one-dimensional 5-moment model, where it is shown to possess many modelling advantages over more standard methods. A two-dimensional numerical scheme is then presented for the parallel solution of the 14-moment bi-Gaussian closure. The multi-dimensional bi-Gaussian closure is compared to another maximum-entropy-based (IMEB) closure in rarefied gas dynamics applications, and to the Gaussian closure in a liquid spray application. Though the closure has compared quite well to the IMEB closure and shown a significant modelling advantage over the Gaussian closure, further improvements to the numerical scheme and closure are required. Une nouvelle fermeture bi-Gaussienne à 14 moments de la hiérarchie d'entropie maximale de Levermore est dérivée et évaluée dans le contexte de la dynamique des gaz raréfiés (RGD) et des croisements de particules (PTC) reliés aux brouillards de gouttes. En premier lieu, une évaluation d'un système cinétique unidimensionnel analogue est entreprise. La fermeture bi-Gaussienne est ici comparée avec des méthodes plus conventionnelles et démontre un net avantage de modélisation. Un schéma numérique bidimensionnel est présenté. Lors de prédictions numériques multidimensionnelles, la fermeture bi-Gaussienne est comparée à une fermeture basée sur la maximisation d'entropie (IMEB) pour des problèmes de RGD, ainsi qu'à la fermeture Gaussienne pour des problèmes de PTC. La fermeture bi-Gaussienne se compare très bien à la fermeture IMEB et démontre un net avantage de modélisation sur la fermeture Gaussienne. Malgré les résultats prèliminaires encourageants, des améliorations au schéma numérique et à la fermeture sont requises.
Design, Simulation, Software Development, and Testing of a Compact Aircraft Tracking Payload for the CanX-7 Nanosatellite Mission
Keywords: ADS-B
Communications
Payloads
Radio
Satellites
Space

Automatic Dependent Surveillance-Broadcast (ADS-B) is quickly becoming the new standard for more efficient air traffic control, but as a satellite/ground-based hybrid system it faces limitations on its usefulness over oceans and remote areas. Tracking of aircraft from space presents many challenges that if overcome will greatly increase the safety and efficiency of commercial air travel in these areas. This thesis presents work performed to develop a flight-ready ADS-B receiver payload for the CanX-7 technology demonstration satellite. Work presented includes a simulation of payload performance and coverage area, the design and testing of a single-feed circularly polarized L-band antenna, the design of software to control the payload and manage its data, and verification of the performance of the hardware prior to integration with the satellite and launch. Also included is a short overview of results from the seven-month aircraft tracking campaign conducted with the spacecraft.
The Investigation and Semi-Empirical Modeling of Thermoacoustic Phase Relationships in a Lean Premixed Prevapourized Combustor at Elevated Pressure
Keywords: Aeronautical
Gas Turbine
High Pressure
Premixed Combustion
Thermoacoustics
Time Lag

This document presents an investigation of the self-excited coupling mechanisms that occur to produce both low-amplitude intermittent, as well as high-amplitude limit-cycle pressure oscillations in an aeronautical gas turbine combustor. Measurements of a lean premixed prevapourized combustor at elevated pressure were conducted using OH* chemiluminescence, pressure transducers, stereoscopic particle image velocimetry and droplet laser scattering. Analysis of the spectra and phase relationships between the measured variables is performed to determine and describe the coupling mechanisms. A semi-empirical model is presented to explain differences in the limit-cycle pressure amplitudes observed under nominally identical operating conditions. Evidence suggests that an oscillating flux of fuel into the combustor is responsible for both intermittent and limit-cycle oscillations, though different coupling relationships are observed in each case. The final amplitude of limit-cycle oscillations is shown to be correlated with changes in the phase difference between the fuel oscillations and the pressure.
Transcutaneous Electrical Nerve Stimulation of Lower Leg Afferents for the Potential Treatment of Overactive Bladder
Keywords: clinical studies
nerve stimulation
overactive bladder
saphenous nerve
tibial nerve
transcutaneous electrical nerve stimulation

Transcutaneous electrical nerve stimulation (TENS) has been used as a neuromodulation therapy for overactive bladder (OAB). There has been limited efficacy shown with non-invasive neuromodulation therapies compared to percutaneous tibial nerve stimulation. TENS therapy has been explored as using the tibial nerve, but preclinical data suggests that during tibial nerve stimulation there is coactivation of the saphenous nerve and that the plantar nerves may be better nerve targets. The goal of this research is to characterize the selective activation of lower leg afferents when stimulated with TENS and to determine the therapeutic efficacy of stimulating the saphenous nerve with TENS for OAB therapy. The clinical studies in this research suggest that the saphenous may be a good nerve target for therapy and its efficacy is explored. Based on these findings, TENS may provide patients with a convenient at-home treatment for OAB allowing them to manage their symptoms.
Effect of Boundary Layer Thickness and Passive Vortex Generators on the Wake of a Blunt Trailing Edge Profiled Body
Keywords: blunt trailing edge
boundary layer thickness
flow control
passive vortex generator
secondary instability
wake

This thesis studies the effect of turbulent boundary layer thickness on the wake dynamics of a blunt trailing edge profiled body, and investigates a flow control technique by applying passive vortex generators with different size and spacing. The boundary layer thickness was varied by changing the model chord to thickness ratio from 30 to 150 and by changing the Reynolds number from 10,000 to 35,000. Consequently, the displacement thickness in this study ranges from 0.077d to 0.319d, which results in a decrease of Strouhal number from 0.202 to 0.168, and increase in formation length from 0.863d to 1.048d, and an increase in the average wavelength of secondary instability from 2.12d to 3.33d. The effectiveness of the passive flow control was found to have little dependence on Reynolds number, and the most back pressure recovery of 30% and formation length elongation of 80% were achieved with the smallest passive vortex generators spaced at 2.4d, which is close to the wavelength of the secondary instability.
Design, assembly, integration, and testing of a power processing unit for a cylindrical Hall thruster, the NORSAT-2 flatsat, and the Vector Gravimeter for Asteroids instrument computer
Keywords: electronic
Hall effect
power
propulsion
space
thruster

This thesis describes the author's contributions to three separate projects. The bus of the NORSAT-2 satellite was developed by the Space Flight Laboratory (SFL) for the Norwegian Space Centre (NSC) and Space Norway. The author's contributions to the mission were performing unit tests for the components of all the spacecraft subsystems as well as designing and assembling the flatsat from flight spares. Gedex's Vector Gravimeter for Asteroids (VEGA) is an accelerometer for spacecraft. The author's contributions to this payload were modifying the instrument computer board schematic, designing the printed circuit board, developing and applying test software, and performing thermal acceptance testing of two instrument computer boards. The SFL's cylindrical Hall effect thruster combines the cylindrical configuration for a Hall thruster and uses permanent magnets to achieve miniaturization and low power consumption, respectively. The author's contributions were to design, build, and test an engineering model power processing unit.
An Advice Mechanism for Heterogeneous Robot Teams
Keywords: Advice
Multi Agent Systems
Reinforcement Learning
Robot Teams

The use of reinforcement learning for robot teams has enabled complex tasks to be performed, but at the cost of requiring a large amount of exploration. Exchanging information between robots in the form of advice is one method to accelerate performance improvements. This thesis presents an advice mechanism for robot teams that utilizes advice from heterogeneous advisers via a method guaranteeing convergence to an optimal policy. The presented mechanism has the capability to use multiple advisers at each time step, and decide when advice should be requested and accepted, such that the use of advice decreases over time. Additionally, collective collaborative, and cooperative behavioural algorithms are integrated into a robot team architecture, to create a new framework that provides fault tolerance and modularity for robot teams.
Transplantation of Directly Reprogrammed Human Neural Precursor Cells to Promote Repair in a Preclinical Model of Stroke
Keywords: HAMC
Ischemia
NPCs
Recovery
Sensorimotor
Translational

Stroke is one of the leading causes of acquired long-term disability worldwide. Cell transplantation is a promising therapeutic intervention. Herein, we explore the efficacy of a novel population of directly reprogrammed human neural precursor cells (drNPCs) to treat the stroke-injured brain. First, we confirmed that drNPCs are neurally committed and established a working model of focal ischemia in SCID/Beige mice that leads to sustained functional deficits. We then transplanted cells 4 days after stroke to test for therapeutic benefits. Sensorimotor assessment, immunostaining, and lesion volume outcomes were used to measure functional recovery, cell survival and differentiation, and tissue repair. Our results demonstrate that drNPCs survive up to one month within the transplanted tissue, primarily differentiate into astrocytes in vivo, promote functional recovery, and do not affect the lesion volume following stroke. These results indicate that drNPCs may be a viable source of cells for clinical application.
Morphing Wings: A Study Using High-Fidelity Aerodynamic Shape Optimization
Keywords: Aerodynamic
Engineering
Morphing Wings
Optimization

With the aviation industry under pressure to reduce fuel consumption, morphing wings have the capacity to improve aircraft performance, thereby making a significant contribution to reversing climate change. Through high-fidelity aerodynamic shape optimization, various forms of morphing wings are assessed for a hypothetical regional-class aircraft. The framework used solves the Reynolds-averaged Navier-Stokes equations and utilizes a gradient-based optimization algorithm. Baseline geometries are developed through multipoint optimization, where the average drag coefficient is minimized over a range of flight conditions with additional dive constraints. Morphing optimizations are then performed, beginning with these baseline shapes. Five distinct types of morphing are investigated and compared. Overall, a theoretical fully adaptable wing produces roughly a 2% improvement in average performance, whereas trailing-edge morphing with a 27-point multipoint baseline results in just over a 1% improvement in average performance. Trailing-edge morphing proves to be more beneficial than leading-edge morphing, upper-surface morphing, and a conventional flap.