VictorJuiz/thesis huggingface dataset:
The Current Shaping Modular Multilevel DC-DC Converter

Modular multilevel converters (MMCs) for dc applications require an internal circulating ac current to balance the charge of the voltage source module capacitors (VSM). While the frequency of this circulating ac current can be freely chosen, in state-of-the-art MMC structures, this frequency is typically limited to 100s of Hz due to the presence of large string inductors and the high number of switching operations, thereby requiring significant ripple power to be filtered by large VSM capacitors. In this thesis, a novel energy transfer mechanism for dc applications is introduced which is unique in that it employs a current source submodule (CSM) to directly control the circulating ac current of the converter, enabling the frequency of the circulating ac currents to be increased by at least two orders of magnitude. This results in a commensurate reduction in VSM capacitor size compared to state-of-the-art MMCs. Based on this current shaping mechanism, several converter structures are proposed to target a wide range of dc applications including applications requiring isolation, high voltage conversion ratios, and bidirectional operational capability. In each of the proposed converter topologies, only a fraction of the VSMs are required to be switched in a given operating cycle enabling a frequency multiplier effect to occur whereby the effective frequency seen by the magnetics of the converter, as well as the VSM capacitors, is much greater than the switching frequency of the individual VSMs. The core ideas of this thesis are validated through experimental work which is performed using a laboratory-scale prototype based on SiC power devices. Peak efficiencies of up to 97.1% were achieved at an effective operating frequency of 50 kHz. The experimental work demonstrates that converters based on this energy transfer mechanism enable substantive converter volume and cost reduction due to a reduction in capacitive and inductive storage requirements.

Keywords: current shaping
high frequency
modular
multilevel dc-dc converter
power electronic transformer
solid state transformer
Advisor: Lehn, Peter W
A "Holy Grail" of Work and Family Life? When and How Schedule Control Functions as a Resource

Schedule control is a job resource used to determine the timing of paid work and has been touted as a “holy grail” among work-family scholars and practitioners. While prior research has demonstrated that schedule control is linked with better work-life balance and health, it may not be an unfettered job reward. With this dissertation, I advance new knowledge that complicates the resource view of schedule control by integrating theoretical perspectives from diverse fields, including scholarship on roles in the work-family interface, sociology of mental health, and occupational health psychology. My dissertation extends prior research by identifying the conditions and statuses under which schedule control functions as a job resource versus scenarios where it might have circumscribed benefits or even unintended consequences for work-family life and health. Three patterns derived from longitudinal data analysis complicate the characterization of schedule control as solely a job resource. First, in Chapter 2 I reveal some of the downsides of schedule control for the work-family interface. I find that increases in schedule control are associated with a greater frequency of blurring the boundaries between work and nonwork roles. Moreover, schedule control exacerbates the association between job pressure and role blurring—and these observed downsides are stronger for women. Second, in Chapter 3 I compare the protective resource functions of schedule control and mastery for mitigating the detrimental health effects of competing work and family roles. I find that mastery has generalized stress-buffering functions whereby it alleviates the health-harming effects of both directions of work-family conflict. In contrast, schedule control has asymmetrical moderating functions: It attenuates the health effects of work-to-family conflict only. Third, in Chapter 4 I identify some of the status-based inequalities in the relationship between schedule control and job pressure. While I find that increases in schedule control help alleviate job pressure, my results reveal that schedule control is more effective in mitigating job pressure among professionals (relative to non-professionals) and those with more managerial power in the workplace. Collectively, this dissertation integrates interdisciplinary theoretical perspectives to advance knowledge on when and how schedule control functions as a resource for workers.

Advisor: Schieman, Scott
Bearing the Weight (of stigma): Examining Weight Stigma, Body Image, and Physical Activity in Adolescents

This research program examined the associations among weight stigma, body image, and physical activity in adolescents using three studies. Given the predominance of cross-sectional research that has investigated these associations, Studies 1 and 2 aimed to better understand the associations among weight stigma, body image, and physical activity using longitudinal and time-varying methodologies. Study 1 (n = 576) used a longitudinal design to assess the reciprocal and prospective associations between body-related self-conscious emotions (shame, embarrassment, authentic pride) and physical activity behaviour over three years in adolescents. Findings indicated that body-related self-conscious emotions at age 14-15 predicted physical activity behaviour one year later. In turn, physical activity behaviour predicted body-related shame and authentic pride another year later. Study 2 (n = 97) used a daily diary approach to explore the between- and within-person associations among experienced weight stigma, internalized weight stigma, and body-related shame, embarrassment, and pride over five days. Higher levels of experienced and internalized weight stigma on average were associated with greater odds of reporting body-related shame and embarrassment. Within-person levels were not associated with any body-related self-conscious emotions, and between-person levels of experienced and internalized weight stigma were not related to odds of reporting body-related pride. Informed by theoretical tenets and Studies 1 and 2, Study 3 (n = 311) tested an integrated and novel model examining the associations among weight stigma (experienced, internalized), body image (body-related shame, embarrassment, authentic pride, body appreciation) and physical activity in adolescents. Partial support for the integrated model was noted, such that higher experienced weight stigma was indirectly associated with lower levels of resistance training through higher internalized weight stigma and lower body-related authentic pride. In addition, higher experienced weight stigma was indirectly associated with higher negative body image and lower positive body image through higher internalized weight stigma. Collectively, these findings provide more comprehensive insight into the negative psychological and behavioural consequences of experienced and internalized weight stigma, and advance understanding of these relationships among the understudied adolescent population. Findings from this research program have implications for individual and system-level mechanisms that should be targeted to foster physical activity in adolescents who experience and internalize weight stigma.

Keywords: Adolescents
Body image
Physical activity
Self-conscious emotions
Weight stigma
Advisor: Sabiston, Catherine M.
Self-Assembled Films of Gold Nanoparticles and Optical and Electrical Phenomena Enabled by Crosslinking

Given the tunable size-dependent electronic and optical properties of gold nanoparticles, such nanostructures offer a rich platform as building blocks for the design and construction of macroscopic materials with tailored physical properties. Control over the average and standard deviation of the size distribution of organic-soluble gold nanoparticle building blocks was investigated through the development of a size-selective precipitation technique. Nonsolvent addition to dodecanethiol-ligated gold nanoparticles resulted in low nanoparticle yields in sorted nanoparticle fractions and a high degree of irreversible aggregation, whereas an intermediate ligand substitution to dodecylamine afforded increased yields and gold nanoparticles with standard deviations in diameter as low as σ < 7%. The effectsof temperature, ligand type, and excess ligand concentration on this system were investigated. Secondly, self-assembled architectures formed by mixtures of dodecanethiol-ligated gold nanoparticles and excess n-alkanethiols (n = 4, 12, 18) on a water surface were studied. Effects of excess alkanethiol chain length, concentration, solvent composition, and uniformity of solvent evaporation were investigated. With suitable solvent compositions and sufficiently long alkanethiol chain lengths, increasing alkanethiol concentration drove a transition over macroscopic length scales between a densely packed 2D gold nanoparticle monolayer phase to a quasi-crystalline ∼1D micropore/bundle network phase. Finally, an extended method was developed to both self-assemble gold nanoparticle monolayers at an air-liquid interface and subsequently crosslink the generated arrays in situ with a variety of dithiolated crosslinkers of varying lengths and structure, and the optical and electronic properties of the resulting 2D crosslinked nanosheets (X-NS) were characterized. Notably, oligophenylene dithiol (HS-(C6H4)n-SH, with 1 ≤ n ≤ 3) X-NS exhibited exponentially increasing conductance with increasing molecular length, as well as an at least ∼6 orders of magnitude increase in molecular ultraviolet-visible extinction coefficients compared with those of unlinked molecules in solution, suggesting wavefunction hybridization at a molecule - nanostructure level. These results demonstrate a rich range of 2D gold nanoparticle architectures that can be self-assembled over macroscopic scales, as well as emergent effects which arise due to the interactions between nanoparticle and crosslinker building blocks of variable molecular properties in such assemblies.

Advisor: Dhirani, Al-Amin
Goh, Cynthia
Trip Reservation and Intelligent Planning (TRiP) for a Hyper-congestion-free Traffic System: In the Context of Pervasive Connectivity, Driving Automation and MaaS

In most cities worldwide, demand for travel exceeds the existing limited road capacity, which causes extended hours of hyper-congestion every day. Hyper-congestion starts when and where demand exceeds capacity on a link, a road or an area, causing capacity loss and severe performance degradation. In this thesis, we design and develop a proof-of-concept system for a trip-level, link-based, in-advance trip reservation and intelligent planning system, dubbed “TRiP”. TRiP is a network-wide methodological system and software platform that facilitates the pacing of travel demand into the existing road network without exceeding the link-level capacity. The system is intended for real-time application, using a dynamic, disaggregated, spatiotemporal, in-advance reservation approach. This thesis introduces three different interconnected pillars. The first is TRiP Abstraction (TRiNAT), which is a set of network abstraction tools developed to facilitate micro traffic management systems. The second pillar is TRiP Assignment (TRiFree), which is a novel traffic assignment algorithm for trip-level, link-based, in-advance reservation traffic control systems that aim to keep all road links hyper-congestion-free. TRiFree, coupled with TRiNAT and a frontend reservation app, create the third pillar: the Trip Reservation and Intelligent Planning (TRiP) platform.To ensure the scalability of the proposed methodology to practical city and region sizes, TRiP was tested on the Toronto, Canada, road network, which includes more than 8,434 road links and serves more than 501,800 vehicles during the peak of the weekday morning commute. Our results show a very promising reduction in total travel time of 18.9-26.6% and a reduction in total travelled distance of 0-2%. The simulation results of the various scenarios outperform existing techniques and introduce a holistic robust solution for enjoying a hyper-congestion-free road network. Unlike other propositions in the literature, TRiP is scalable for larger road networks. Therefore, this thesis offers a major contribution to state-of-the-art and state-of-the-practice traffic control systems.

Keywords: algorithm
big data
control
intelligent
reservation
traffic systems
Advisor: Abdulhai, Baher
"We are Stories, Not Labels:" Anishinaabekweg Childrearing Experiences

First Nations mothers are subject to various colonization attempts, including labelling as deviant parents, both in historical and contemporary contexts. Through the application of a micro-lens to one Anishinaabeg community, known as Opwaaganisiniing or the Red Rock Indian Band, in Northern Ontario, this research 1) highlights how Euro-Canadian labels, both past and present, have impacted childrearing and 2) uncovers resistant and persistent Anishinaabe mothering principles and practices. Decolonizing Praxis and Indigenous Methodology supplement the western theoretical approach of Labelling Theory. Labelling Theory has never been applied to Indigenous communities; however, it can be useful to describe how dominant societal labels can be damaging (causing shame and stigma) yet inversely empowering (developing resistance) for marginalized peoples. An archival study looked at historical government and religious documents to determine the historical labels applied to people in the community, and 14 Indigenous female parents were recruited from members of the Red Rock Indian Band to determine the contemporary labels that exist today. A conversational methods approach was used to elicit labels and stories from the parents. Indigenous narrative methods were undertaken to draw out meaning from the stories and anecdotes told by the parents. Despite the persistence of historical labels, it was found that contemporary parents use kinship and reclamation to resist these labels.

Keywords: Anishinaabeg
First Nations
Indigenous Health
Labelling Theory
Motherhood Studies
Advisor: Smylie, Janet
The Origins of the Herbarium of Pseudo-Apuleius

The Herbarium of Pseudo-Apuleius is a late antique text describing the medicinal uses of 131 plants. This herbal was a popular medical work of early medieval western Europe, and the text therefore serves as a valuable representation of the medical beliefs and practices of the period. Despite the herbal’s significant presence in medieval Europe, most aspects of the herbal’s origins, such as the text’s original author, remain mysterious, while the theories about the herbal’s creation have been based on supposition and require reevaluation. This dissertation examines three aspects of the herbal that have need of reassessment: the text’s location of composition, the text’s date of composition, and the original intent of the work.The thesis demonstrates that the evidence used to support the common scholarly consensus for dating and locating the origin of the Herbarium in fourth-century North Africa requires reassessment, and argues that the intrinsic evidence of the text and applied source criticism suggests a much broader area of the Mediterranean (with some evidence for Italy), and a potentially earlier date. Using the preface as a framework for discussion, this dissertation also examines the herbal’s medical content and demonstrates how various aspects of the text, such as the herbal’s medical epistemology, align with the preface’s claims and also with the late antique genre of the practical medical handbook. Moreover, analysis of the herbal’s format and organization suggest elements of learned medicine beyond the level of a practical or amateur handbook. Finally, this dissertation offers a modern English translation of the herbal, the Latin version of which has never been translated into modern English.

Keywords: Ancient History
Medieval History
Science History
Advisor: Everett, Nicholas
Synthesis and Analysis of Two-dimensional Surface Phases in the Bi/Si(111) System by Scanning Tunneling Microscopy and Density Functional Theory

The Bi/Si(111) surface reconstruction is an attractive two-dimensional (2D) surface phase due to its compatibility with current Si-based electronic industry and due to its extraordinary Rashba spin splitting feature favorable for spintronics fabrication. However, detailed defect analysis and quantum dot creation in this system have not been reported. Here, using scanning tunneling microscopy (STM) and density functional theory (DFT), defects, quantum states and phase transformation mechanisms of the Bi/Si(111) system and the Pb/Bi/Si(111) system are studied separately. First, bias dependence and defects in the Bi/Si(111) √3×√3 β-phase are analyzed. It is confirmed that the honeycomb pattern at low-bias empty states and a hexagonal-closest-packed pattern at high-bias empty states originate from the Bi px, py states and Bi, Si overlapped states outside bulk bandgap, respectively. Analysis of the defect images and their associated densities of states provides further insight into the electronic structure of the surface. Second, crystal structure and quantum well states (QWSs) of the Pb/Bi/Si(111) 2D phase are researched. The atomic structure of the system is confirmed by STM images combined with DFT calculations. QWSs and a sizable Rashba band splitting are predicted with the latter comparable to what is found in other semiconductor heterostructures and an order of magnitude higher than that in Pb/Si(111) QWSs. Finally, quantum dot states (QDSs) are discovered in the √3×√3-Bi/Si(111) surface phases. The structure, energy dispersion, and size effect on the electronic states of the QDs are measured and verified. As-created QDs can be manipulated with a dot size down to 2 nm via Bi phase transformation, which in turn is triggered by thermal annealing at 700K. The transition mechanism is also supported by DFT calculations, and an empirical analytical model is developed to predict the transformation kinetics.

Keywords: Bi/Si(111)
DFT
STM
Advisor: Nogami, Jun
Singh, Chandra Veer
Patterns of Species Co-occurrence, Null Models, and the Influence of Biotic and Abiotic Factors: A Species Pairwise Approach

How natural communities are structured and what factors influence such structure has been a pervasive subject in ecology for more than one century. Among several approaches used to determine the structure of communities, species co-occurrence analysis has been a subject of controversy since the classical debate between Diamond and Connor-Simberloff. Their main contrasts were whether ecological communities differed from random groupings of species, the role biotic factors had in generating the observed assemblage patterns, and the methods to discern structures of communities different from random (null models). Here, my main goals were to improve approaches to species co-occurrence analysis, to improve our ability to discern whether communities are structured non-randomly, and to extend them to testing hypotheses related to ecological mechanisms. First, I analyzed co-occurrence patterns using a species pairwise approach, different from the typical whole-community approach, to discern the relationship between multiple species of lake fishes across thousands of lakes in Ontario. Specifically, I tested whether the co-occurrence patterns observed across multiple species pairs from several different watersheds exhibit consistent patterns. I used subsets of species to test specific hypotheses related to the roles of predation, competition, and environmental filtering in structuring fish communities. Following, I examined the influence of habitat size on the observed co-occurrence patterns. I compared species co-occurrence patterns across different categories of lake area and depth to determine whether and how these variables affected the associations observed among multiple species pairs. Finally, I determined whether species-pair associations can be predicted from simple ecological traits. I analyzed the relationship between three biologically relevant traits (body size, temperature preference and trophic level) and the co-occurrence values observed between each species pair. I detected a significant effect of temperature preference and trophic level on the observed co-occurrence patterns. Unexpectedly, body size did not exhibit a significant effect on the co-occurrence patterns. My research showed the strong effect of interspecific predation on community composition, that signals of non-random community assembly are strongly dependent on the abiotic conditions, that analyses at the whole-community level may dilute underlying ecological signals, and that species co-occurrence patterns reflect differences in species traits.

Keywords: aquatic ecology
habitat size
null model analysis
Ontario lakes
Species co-occurrence patterns
trait-based analysis
Advisor: Jackson, Donald
From Classical Music to Contemporary Music Theatre: A Pedagogical Compendium for the Crossover Teacher

The landscape of the collegiate voice teacher has changed considerably in recent years. From 2010–2016 total enrollment of vocal performance majors has declined 23% while enrollment in music theatre programs has grown by 33%. Research on cross-training in students earning undergraduate and graduate degrees in voice performance revealed nearly two-thirds of 2017 graduates did not receive specific training regarding the commonalities or differences between singing music theatre and opera, while 60% of graduates did not feel prepared for the current demands of either style (Saunders-Barton and Spivey, 2018). Classical music schools and conservatories are increasingly offering voice performance degrees in contemporary commercial music (CCM) styles (i.e., those found in music theatre such as country, folk, rock, pop, hip-hop and rap, gospel, and R&B), yet there are only three graduate programs for non-classical vocal pedagogy across North America.Although these vocal styles are widespread in contemporary culture and contemporary music theatre, the development of crossover vocal pedagogy based in voice science and functional physiology is nascent. In response to the need for functional crossover vocal pedagogy, this dissertation addresses the concerns of voice instructors in teaching current music theatre styles. Using lesson observations, this work will also act as a comparative assessment on stylistic and technical points of convergence and divergence between CCM styles found in music theatre and classical singing, culminating in a practical pedagogical compendium for the crossover teacher. Chapters 1– 3 examine the history of music theatre styles, assess commonalities and differences between CCM resources, and provide evidence-based research for use in the crossover lesson setting. The compendium of Chapter 4 is designed to help classical voice instructors teach the CCM styles of music theatre. Ultimately, commonalities found in Body Engagement, Imagery or Analogy, Questions to Facilitate Learning, Physical Demonstration, and Vocal Demonstration offer classical teachers confidence in their existing pedagogical knowledge when teaching contemporary music theatre. Divergent themes in Acting, Alignment, Registration, and Resonance highlight the need for further study of functional vocal pedagogy in CCM styles.

Advisor: MacDonald, Lorna