VictorJuiz/thesis huggingface dataset:
Modeling, Analysis, and Control of Close Formation Flight
Keywords: Close formation flight
Cooperative control
Formation control
Robust adaptive control
Robust nonlinear control
Unmanned aerial vehicles

Close formation flight is extensively investigated from the perspectives of dynamic modeling, aerodynamic analysis, and control design. A lifting-line based aerodynamic model is presented to describe the aerodynamic coupling between two aircraft in close formation. The introduced aerodynamic model is validated via the comparison with a single horseshoe vortex-based model, a vortex lattice method-based model, and experimental results. Comprehensive analysis is thereafter conducted to investigate the drag reduction variations with respect to different relative positions, angles of attack, sideslip angles, and leader-to-follower wing span ratios. The analysis indicates that the drag reduction performance of close formation flight is sensitive to the formation position accuracy. Additionally, basic requirements are formulated for close formation flight control. In terms of the proposed aerodynamic model, a linear robust adaptive formation controller is developed specifically for close formation at level and straight flight. The proposed robust adaptive controller shows dramatic increase in both transient performance and robustness against model uncertainties and disturbances. The nonlinear robust close formation control problem is thereafter studied under a leader-following architecture. Nonlinear robust close formation controllers with different considerations are proposed based on a command filtered backstepping method and an uncertainty and disturbance estimation technique. The proposed nonlinear robust formation controllers could accommodate more complex flight scenarios, for instance, different flight maneuvers and close formation of more than three aircraft. With the increase of the number of aircraft in close formation, a leader-following formation controller might become less and less efficient. Regarding the efficiency degradation issue of leader-following formation controllers, two cooperative control algorithms are introduced, which exhibit better tracking performance for close formation of a large number of aircraft. Extensive simulations are carried out to validate the effectiveness of all proposed close formation control algorithms.
Electroanalytical Techniques for Digital Microfluidics
Keywords: digital microfluidics
electrochemistry
potentiostat

Digital microfluidics (DMF) is a miniaturised fluid-handling technique used to manipulate nanolitre to millilitre droplets of liquids across arrays of electrodes insulated with a dielectric material. While many analysis techniques have been used in conjunction with DMF, inline analysis techniques, in which droplets can be examined or sampled directly from a DMF device, are of particular interest, reducing complexity and allowing real-time monitoring. Many techniques including optical and mass spectrometric methods were established previously, but until recently there were few reports of electrochemical detection being employed with DMF. Electrochemical analysis techniques have important advantages in sensitivity, selectivity, and instrumental expense and complexity, and are often well-suited to integration with DMF due to their compatibility with miniaturisation. This thesis introduces the first advanced use of electroanalytical techniques with DMF as well as a robust toolkit for the most common electroanaytical techniques, suitable for DMF as well as the general analytical laboratory. Chapter 2 demonstrates the integration of voltammetry within a DMF device and the utility of such a combination by producing an analyte calibration curve from microscale samples with minimal intervention. Chapter 3 describes the DStat, an open-source potentiostat designed for electrochemical measurements at low current and easy integration into other systems. The latter is exploited to couple the DropBot DMF system with the DStat allowing fully automated fluid handling and voltammetric measurements. The DStat's capabilities are further expanded in Chapter 4 and Chapter 5 to encompass Electrochemical impedance spectroscopy (EIS), with the development of an accessory high-frequency impedance module and software and firmware adaptations to allow low-frequency impedance measurements with the existing DStat hardware. As exemplary applications, high-frequency EIS is used to verify the thickness of the hydrophobic layer on DMF devices, and low-frequency impedance measurements are used in the study of DMF device failure as a result of water infiltration into the dielectric layer. This thesis encompasses not only the development of methods for integrating electrochemical detection and DMF, but a versatile instrumental infrastructure for performing the most common electroanalytical techniques for DMF, the analytical lab, and beyond.
Regulation of Breast Cancer Cells’ Bone-Metastatic Potential by Mechanically Stimulated Osteocytes
Keywords: bone metastasis
breast cancer
endothelial cells
mechanical stimulation
osteoclasts
osteocytes

Bone metastasis, the migration of cancers to the bone, occurs in 65-75% of patients with advanced breast cancer and significantly increases patients’ morbidity and mortality. The bone-metastatic cancer cells interact with cells in the bone to disrupt the bone remodeling balance, causing reduced bone quality and other complications while facilitating tumor growth. Bone remodeling cells can be regulated by osteocytes, the major population of cells in the bone that are embedded in the bone matrix, in response to dynamic loading on the bone. Osteocytes also signal to blood vessel-lining endothelial cells that interact closely with cancer cells during early metastasis before a secondary tumor is established in the bone. Therefore, we hypothesized that mechanically stimulated osteocytes may regulate cancer cells directly and via other cells. To investigate, we mimicked what osteocytes experience in vivo during bone-loading activities, such as walking, with oscillatory fluid flow. We observed that factors secreted by flow-stimulated osteocytes increase cancer cell migration and survival. Contrastingly, signaling from flow-stimulated osteocytes through bone-resorbing osteoclasts or endothelial cells to cancer cells were anti-metastatic. Specifically, it reduced cancer cell migration, survival, and invasion. Factors secreted by flow-stimulated osteocytes also reduced cancer cells’ trans-endothelial migration and endothelial monolayers’ permeability and ability to be adhered by cancer cells. These demonstrated the capability of mechanically stimulated osteocytes in reducing the bone-metastatic potential of breast cancer cells by signaling through osteoclasts and endothelial cells. Investigating this regulation further can provide novel insights into the potential of bone-loading exercise in preventing bone metastasis.
Computational Modelling of Progressive Damage in Viscoelastic-viscoplastic Composite Materials
Keywords: Damage
Finite Element Analysis
Multi-scale modelling
Viscoelasticity

Current governmental requirements for greater fuel efficiency are pushing automotive manufacturers to find innovative ways of reducing car weight, while still maintaining mechanical performance to ensure passenger safety. Composite materials would allow for significant weight reduction, while still maintaining a safe environment for the passengers. However, composite materials are known to exhibit significant time-dependent behaviour, as well as progressive damage which affect structural performance. Bio-composites in particular are known to undergo complex damage evolution during their lifetime. In this thesis, a multi-scale computational approach has been adopted to take these effects into account. A new modelling approach based on Synergistic Damage Mechanics to understand damage evolution in composite materials undergoing time-dependent deformation is developed. The model is applied to matrix micro-cracking in laminates. Computational micro-damage mechanics is combined with a continuum level description of stiffness degradation to predict the evolution of micro-cracking while requiring minimal experimental calibration. The time-dependent behaviour is modelled using Schapery’s theory of viscoelasticity and viscoplasticity, and the evolution of matrix micro-cracking during creep is predicted. The predictions of the model for different stacking sequences, ply thicknesses and working temperatures show that viscoelasticity and viscoplasticity have a significant effect on the long-term response of laminates undergoing matrix micro-cracking. The multi-scale modelling approach is extended to short fiber bio-composites by constructing a micro-damage model of fiber-matrix debonding using a Cohesive Zone Model. The effect of strain rate on fiber-matrix debonding is analyzed by implementing a non-linear viscoelastic model for the matrix, and it is shown that viscoelastic behaviour leads to a competition between void nucleation and debonding. The effects of fiber stiffness, dimensions and interfacial shear strength are evaluated. Following the micro-damage analyses, the thesis focuses on damage evolution at the structural scale by implementing the damage model in Finite Element Analysis software to analyze the dynamic response of a car bumper. The rate-dependent evolution of damage is predicted for different stacking sequences and material systems.
Revisiting the Cambrian Burgess Shale Palaeocommunity in Light of New Field Discoveries from Marble Canyon, Kootenay National Park, British Columbia
Keywords: Burgess Shale
Cambrian
Community ecology
Evolutionary Biology
Paleoecology
Paleontology

The 508-million-year-old Burgess Shale (British Columbia) is among the most important fossil localities in the world as it provides a direct window into the Cambrian Explosion, the phenomenon whereby most metazoan groups appeared rapidly in the fossil record for the first time. For over 100 years, Burgess Shale fossils have provided unique insights into the early evolutionary history of animal life, but a holistic description of the community ecology of the Burgess Shale has remained elusive. This dissertation aims to reinvestigate the Burgess Shale paleocommunity in light of the recently discovered Marble Canyon fossil site in Kootenay National Park, integrating this new dataset with those from the type areas in Yoho National Park, 40km to the northwest (Walcott Quarry, Raymond Quarry, and Tulip Beds). The first three chapters of this dissertation focus on the organismal level. An experimental decay study (Chapter 1) provides a framework for the interpretation of taphonomic bias in community reconstructions. The redescription of three enigmatic Cambrian taxa (Chapters 2 and 3) provide novel phylogenetic and ecological information for understanding the patterns of diversity and niche structure at Marble Canyon. The community analysis (Chapter 4) represents the largest quantitative study of the Burgess Shale to date. Patterns of faunal stasis between most adjacent bedding assemblages followed by periodic variations in abundance and species identity are found at both Marble Canyon and Walcott Quarry, the two best-studied sites with the finest level of stratigraphic/temporal data. Across the entire Burgess Shale paleocommunity, major shifts in representative taxonomic groups and ecological modes occur between major localities. The results of this work suggest that the Burgess Shale as a paleocommunity was highly heterogeneous in both its taxonomic and ecological composition. Shifting abiotic and environmental variables are determined to be more significant in the long-term structuring of Burgess Shale communities than species interactions such as predation, which was previously considered paramount.
Constructing Parental Choice in Deaf Diagnostic and Intervention Practices in Ontario
Keywords: cochlear implants
communication
deaf children
language
parental choice
(re)habilitation

The goal of Ontario’s Infant Hearing Program (IHP) is to screen all babies at birth, to identify the 3 or 4 out of 1000 babies expected to be deaf or hard of hearing from birth, and to provide supports and services to identified children under the age of six. Situating my research within disability studies to question normative assumptions about speech, language, and hearing, through interpretive analyses of IHP documents and parental interviews I examined how language and deafness are made meaningful through text and lived experience, and how parents come to make hearing technology and communication modality choices for their children amongst competing discourses of deafness and language. Although the identification of these few children is the IHP’s justification for screenings, I found the discourse of screening constitutes these children’s hearing levels as problematic and unwanted. Normative assumptions construct parental choice by presenting deafness as an unthinkable outcome of screening and spoken language services as the ‘right’ way to deal with this outcome. I also found the services and hearing technologies offered, and when they were offered, differed depending on whether a child has additional diagnoses and are assumed able to learn spoken language, demonstrating a hierarchy of normalization. Furthermore, the IHP’s principle of fully informed choice and consent was found to narrowly reflect medical knowledges of deafness; comprehensive information about sign language and Deaf culture was not included. My analysis also found parents may resist medical knowledges of deafness and request alternate services as they get to know their child beyond diagnostic assumptions. These findings indicate parents and their children may be better aided by services that promote a wider variety of communication options from infancy, regardless of expected outcomes. My dissertation concludes with an exploration of ways the IHP can imagine deafness as something other than a problem.
Essays in Empirical Asset Pricing
Keywords: Asset Pricing
Financial Econometrics
Human Capital
Investments

In my dissertation, I study different channels through which shocks in the real economy can affect financial asset returns. The first chapter studies immigration policy shocks as a source of risk in the financial markets. Using a comprehensive set of data on H-1B visa petitions, I construct an occupation-level measure for labor market competition between skilled immigrant and local workers. I find that stocks of firms with a high share of labor for which skilled immigrants are close substitutes outperform their peers with a low share. I show that this premium is explained by firms' differential exposures to priced immigration policy shocks that shift the supply of skilled immigrant labor. These shocks differentially impact wages across occupations, leading to an asymmetric effect on firms' cash flows through labor expenditure. In the second chapter, based on a joint work with Esther Eiling and Raymond Kan, we investigate the asset pricing implications of sectoral labor reallocation shocks that change the optimal allocation of workers across industries. We find that a proxy for this type of labor market shocks has very strong predictive power for future stock market returns. We propose a production-based asset pricing model that links the return predictability to time-varying labor adjustment costs. When human capital is tied to the industry, hiring workers from other industries involves more search and training costs. Hence, sectoral reallocation shocks lead to lower returns to hiring and therefore lower future stock returns. In the third chapter, we identify inter-sectoral trade networks as important conduits of industry shocks and provide the first explanation for an empirical regularity in the term structure of industry returns. Specifically, my co-author Mikhail Simutin and I show that industry shocks propagating along this network can feed back to the originating industry, causing an "echo'' - intermediate-term autocorrelation in returns. Adopting techniques from graph theory, we find that the strength of the trade network feedback is a crucial determinant of the echo effect in industry returns. Consistent with limited-information models, the relation between feedback strength and echo profits is strongest in industries with information diffusion frictions along the feedback loop.
ADC-based Receivers for Wireline Communication
Keywords: ADC
FinFET
Greedy Search
PAM
receiver
SERDES

Power efficient analog to digital converter (ADC) based receivers are desired for wireline communications as the industry transitions to 4-PAM at data-rates above 50Gb/s. A high power time-interleaved successive approximation register (SAR) ADC with 7 or 8 bit resolution is usually used to cover high loss (>=30dB at Nyquist frequency) channels with cross-talk. However the majority of links within a data-center between servers and switches are around medium loss (20dB) or lower. In order to take advantage of the direct correlation between loss and power consumption, a novel greedy search based power scaling scheme with BER metric is proposed so that the ADC can be adapted to work at the minimum power required by any given link. Unlike prior art, this strategy does not require finer threshold levels and works in conjunction with any equalizer. In addition, system level simulations are developed to aid receiver design and dynamic error sources such as jitter, skew and dynamic non-linearity are investigated. It is shown that typical ADC design targeting an effective number of bits across the entire Nyquist band may be over-designed as dynamic effects are reduced due to channel attenuation. A 64Gb/s 4-PAM ADC-based receiver prototype was tailored for link power scaling and fabricated in a 16nm FinFET technology. The receiver analog front-end consists of a single stage half-rate sampling continuous time linear equalizer, and 6-bit flash (1-bit folding) ADC taking advantage of sampled input distribution symmetry to enable non-uniform quantization. For a channel with -8.6dB loss at Nyquist, the ADC can be configured in 2-bit mode, achieving BER
‘For the Happiness of the World’: The Geopolitics of Great Power Intervention, 1815-2015
Keywords: Cold War
Concert of Europe
Geopolitics
Great powers
military intervention
spheres of influence

Why do great powers sometimes invest significant resources in efforts to secure approval from other great powers for their interventions, but other times do not? This dissertation argues that explicit or implicit agreements between great powers called geopolitical bargains have shaped great power intervention by delineating where they can acceptably intervene. When a great power intervenes in an area that a geopolitical bargain delimits as its own area of preponderance—its sphere of influence—it need not worry about making its intervention acceptable to its peers, and it can tailor its intervention coalition to closely meet its military needs. When it intervenes outside of its sphere, the great power must resort to other methods to legitimize its actions, such as formal multilateralism and legal approval. I trace the effects of geopolitical bargains across three periods of great power peace: the Concert of Europe, the Cold War, and the post-Cold War era.
Exploring the Existence of a Unique Neurodevelopmental Profile of Fetal Alcohol Spectrum Disorder
Keywords: Fetal alcohol spectrum disorder
Neurodevelopmental profile

There is a general lack of consensus in the diagnostic criteria of Fetal Alcohol Spectrum Disorder (FASD), which has ultimately resulted in the overlapping of the diagnostic criteria with those of other neurodevelopmental disorders. As a result, FASD is associated with multiple potentially comorbid neurodevelopmental disorders, namely externalizing disorders. However, the extent to which FASD co-occurs with such disorders is largely unknown. Furthermore, the lack of universally accepted diagnostic criteria, and the high rate of comorbidity make diagnosing FASD difficult. Accordingly, in an effort to improve the diagnosis of FASD, researchers have explored the existence of a neurodevelopmental profile of FASD – defined as the outward expression (behavioral and developmental) of the central nervous system damage caused by prenatal alcohol exposure – however, a neurodevelopmental profile unique to FASD remains to be identified. Therefore, the objective of the current thesis project was to i) determine to what extent neurodevelopmental disorders with prominent externalizing behaviors co-occur among children with FASD; and ii) determine if children with FASD exhibit a unique and discernible neurodevelopmental profile that will differentiate them from a) typically developing control children, and b) children with other neurodevelopmental disorders. The first objective was achieved by way of a comprehensive systematic literature search, followed by disorder-specific random-effects meta-analyses. The second objective was achieved by performing latent profile analyses on two samples – i) children with FASD and typically developing control children, and ii) children with FASD, children with other neurodevelopmental disorders and typically developing control children – using data on neurodevelopmental status and behavior. With respect to the prevalence of neurodevelopmental disorders with prominent externalizing behaviors among children with FASD, of the disorders investigated, Attention Deficit Hyperactivity Disorder was found to be the most common disorder, followed by Oppositional Defiant Disorder, Conduct Disorder and Autism Spectrum Disorder, in that order. In relation to the identification of a neurodevelopmental profile, the profile was successful in differentiating children with FASD from typically developing control children; however, it was unsuccessful in differentiating children with FASD from children with other neurodevelopmental disorders. These findings are reflective of the complexity of FASD and highlight the need for diagnostic refinement.