VictorJuiz/thesis huggingface dataset:
Photoacoustic Imaging for Characterizing Blood Clots and Demyelinated Structures in the Brain

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.

Keywords: Imaging
Photoacoustic
Photothrombosis
Advisor: Levi, Ofer
Drake, James
Conjugate Heat Transfer and Sooting Propensity of Ethanol for Laminar Coflow Diffusion Flames at Elevated Pressures

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.

Keywords: Combustion
Computational Fluid Dynamics (CFD)
Emissions
Laminar Flame Speed
Soot
Temperature
Advisor: Groth, Clinton P. T.
Electromagnetic Actuation for a Dragonfly Inspired Flapping-Wing Micro Aerial Vehicle

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.

Keywords: Dragonfly
Microaerial Vehicles
Advisor: D'Eleuterio, Gabriele
Effect of Freestream Turbulence on Laminar Separation Bubbles and Flow Transition on a Low Reynolds Number 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.

Keywords: Freestream Turbulence Effects
Laminar Separation Bubbles
Low Reynolds Airfoil
Advisor: Lavoie, Philippe
Fourteen-Moment Maximum-Entropy-Inspired Closures for Non-Equilibrium Gases and Liquid Sprays

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.

Keywords: Liquid Sprays
Maximum Entropy
Moment Closures
Non-Equilibrium Flows
Rarefied Gas Dynamics
Advisor: Groth, Clinton P. T.
Design, Simulation, Software Development, and Testing of a Compact Aircraft Tracking Payload for the CanX-7 Nanosatellite Mission

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.

Keywords: ADS-B
Communications
Payloads
Radio
Satellites
Space
Advisor: Zee, Robert E.
The Investigation and Semi-Empirical Modeling of Thermoacoustic Phase Relationships in a Lean Premixed Prevapourized Combustor at Elevated Pressure

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.

Keywords: Aeronautical
Gas Turbine
High Pressure
Premixed Combustion
Thermoacoustics
Time Lag
Advisor: Steinberg, Adam M.
Transcutaneous Electrical Nerve Stimulation of Lower Leg Afferents for the Potential Treatment of Overactive Bladder

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.

Keywords: clinical studies
nerve stimulation
overactive bladder
saphenous nerve
tibial nerve
transcutaneous electrical nerve stimulation
Advisor: Yoo, Paul B
Effect of Boundary Layer Thickness and Passive Vortex Generators on the Wake of a Blunt Trailing Edge Profiled Body

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.

Keywords: blunt trailing edge
boundary layer thickness
flow control
passive vortex generator
secondary instability
wake
Advisor: Lavoie, Philippe
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

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.

Keywords: electronic
Hall effect
power
propulsion
space
thruster
Advisor: Zee, Robert E
An Advice Mechanism for Heterogeneous 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.

Keywords: Advice
Multi Agent Systems
Reinforcement Learning
Robot Teams
Advisor: Emami, Mohammed R
Transplantation of Directly Reprogrammed Human Neural Precursor Cells to Promote Repair in a Preclinical Model of Stroke

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.

Keywords: HAMC
Ischemia
NPCs
Recovery
Sensorimotor
Translational
Advisor: Morshead, Cindi M
Morphing Wings: A Study Using High-Fidelity Aerodynamic Shape 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.

Keywords: Aerodynamic
Engineering
Morphing Wings
Optimization
Advisor: Zingg, David W
Cellular Imaging of Human Embryonic Stem Cells using a New Positive-Contrast Magnetic Resonance Contrast Agent

Human embryonic stem cells (hESCs) have the unique potential of developing into all the different cell types in our body and represent a clinically relevant cell source in the field of regenerative medicine. At present, we can inject cells and monitor their progress only in animals but not in humans (and this we do through sacrifice and histology to determine if the cells have survived or migrated). In human trials, these invasive methods cannot be applied, and information can be garnered only when tissue samples are retrieved, which is possible under rare circumstances. To address the need for a non-invasive method to monitor and guide cellular therapy in humans, we have explored a MRI based cell-tracking method that utilizes a positive-contrast manganese porphyrin agent, MnP-TPPS-NH2, that has better sensitivity and safety than gadolinium-based compounds and is easy to scale up due to simplicity of synthesis. In this study, we investigate for the first time the efficacy of cell-permeable MnP-TPPS-NH2 for labeling hESCs. We have demonstrated a significant reduction in T1, leading to large increase in bright signal relative to the background. We have shown the agent has no adverse effects on cell survival and function and that the agent is internalized with higher concentrations inside the nucleus and along the membrane periphery. We have presented a facile and easily scalable new method for sensitive MRI tracking of human embryonic stem cells to accelerate and enable future studies in the complex and interdisciplinary field of regenerative medicine.

Keywords: Cell Tracking
MRI
Regenerative Medicine
Stem Cells
Advisor: Cheng, Hai-Ling
Non-Adhesive Wound Dressings for Burn Patients

Wounds can be caused by a number of reasons including trauma, surgical procedures, or burns. Current would dressings are frequently made of hydrophilic materials, causing them to adhere to exposed wound tissue and exudate, resulting in damage to the healing wound and pain upon dressing changes. This project designed and tested a novel non-adhesive wound dressing that does not adhere to the underlying wound tissue upon removal, and also discourages the growth of bacterial biofilm on its surface, while still allowing for exudate absorbance. Cellular adhesion tests were conducted with both eukaryotic and prokaryotic cells, comparing the novel wound dressings to commercially-available dressings indicated for use on burn wounds. Results showed that the novel dressings adhered to less human fibroblast cells and P. aeruginosa biofilm after 3 days. An effective non-adhesive wound dressing, with antimicrobial abilities, would significantly benefit both the patient and the healthcare system as a whole.

Keywords: Antimicrobial
Burns
Clinical engineering
Non adhesive surfaces
SLIPS
Wound dressing
Advisor: Hatton, Benjamin D
The Development and Evaluation of a User Interface for an Intelligent Power Wheelchair to Increase its Usability for Older Adults

Older adults (â Ľ 65 years) are the most prevalent wheelchair users in North America but many cannot safely drive a wheelchair due to physical/cognitive impairments. Intelligent wheelchairs (IWs) could be a solution, but are minimally clinically validated/commercialized since research has always focused on the underlying intelligent system, rather than the user's needs. Following prototype development of a multimodal user interface, based on recommendations from prior research, a usability study was conducted with three participants using single-subject research design. The multimodal interface (auditory, visual, haptic) gave warnings before obstacles, and provided instructions on how to navigate away from obstacles. Wizard-of-Oz, a technique where the subject believes the system to be autonomous, but is actually human-operated, was used to simulate IW autonomy. High device acceptance was found. Some observable, but not conclusive, improvements were found in usability of the device. Further development and investigation of the user interface is recommended.

Advisor: Mihailidis, Alex
AN ANALYSIS OF POSITIVE SOCIAL INFORMATION-PROCESSING, AGGRESSION, AND PEER FUNCTIONING AMONG CHILDREN WITH ATTENTION DEFICIT/HYPERACTIVITY DISORDER

Research has used social information-processing (SIP) theory to explain the association between social cognitive deficits among children with Attention Deficit/Hyperactivity Disorder (ADHD) and social dysfunction (aggression, low prosocial behaviour, peer problems). Scant research has investigated positive information-processing and social outcomes. This study examined SIP (cue encoding and attributions) of positive social situations among children with ADHD (n=77) and typically developing children (n=48) and explored whether SIP mediated the relation between ADHD symptoms and social outcomes. Results indicated that children with ADHD encoded more overall cues and neutral cues than typically developing children. Typically developing children encoded a significantly higher number of positive and negative cues than children with ADHD. There were no significant differences in intent attributions; however, children with ADHD provided more negative outcome attributions. SIP did not mediate the association between hyperactive-impulsive symptoms and peer problems. Elevated aggression did not moderate the association between SIP and social outcomes.

Keywords: ADHD
Peer Problems
Social Cognition
Social Functioning
Social Information Processing
Advisor: Andrade, Brendan F
Waschbusch, Daniel
Pilot Study Investigating the Impacts of Behavioural Inattention and Meta-Attention on Post-Secondary Students' Online Information Seeking for Academic Purposes

Success at the graduate level of postsecondary education requires proficiency with academic online information seeking. Navigating the internet to find information is a complicated task that is vulnerable to lapses in attention. This study examined the relationships between graduate studentsâ self-reported behavioural inattention symptoms, meta-attention and online academic information seeking abilities. One-hundred and thirteen (99 female) graduate students (83 Masters-Level, 27 Doctoral Level) completed an online self-report questionnaire examining behavioural inattention symptoms, meta-attention, time-management and online information seeking ability. Results indicated that self-reported inattention, meta-attention, experience, and diagnostic status each significantly predicted unique variance in online information seeking ability. Implications for future research and intervention are discussed.

Keywords: attention
e-learning
information seeking
meta-attention
online information seeking
Advisor: Martinussen, Rhonda