VictorJuiz/thesis huggingface dataset:
Development of a Transition Prediction Methodology Suitable for Aerodynamic Shape Optimization
Keywords: aerodynamic shape optimization
aircraft design
boundary-layer transition
computational fluid dynamics
natural laminar flow
transition prediction

Aircraft configurations that exploit significant regions of natural laminar flow could play a key role in reducing the environmental impact of aviation. The design of natural-laminar-flow configurations can be accelerated using computational tools capable of accurately and efficiently predicting boundary-layer transition. Toward the development of a suitable computational design tool, methods for the efficient prediction of boundary-layer transition in a Reynolds-averaged Navier-Stokes-based flow solver and integration in a discrete-adjoint gradient-based optimization algorithm are presented. A local correlation-based transition model is modified and coupled to the Spalart-Allmaras turbulence model and integrated in a Newton-Krylov-Schur flow solver. Modifications to the solution strategy are introduced, including a source-term time step restriction, in order to prevent unstable solution updates for the fully coupled, fully implicit solver. A smooth-variant of the transition model is developed with approximations to discontinuous and stiff source-term functions. Both transition models are validated using two- and three-dimensional subsonic transition test cases, with the new, smooth model producing significantly improved iterative convergence. Compressibility corrections are developed and applied to extend the transition model empirical correlations to transonic flow regimes typical of commercial transport aircraft, with the resulting model investigated using two- and three-dimensional transonic transition test cases. The results demonstrate that the compressibility corrections produce substantially improved agreement with the experimental transition locations, particularly for higher Reynolds number applications. Finally, the smooth transition model is integrated in a discrete-adjoint gradient-based optimization algorithm and applied to two- and three-dimensional drag-minimization studies across a range of design conditions. The results demonstrate that the capability of the current framework to explore the natural-laminar-flow configuration design space is sensitive to the streamwise grid resolution in the transition regions, with grid requirements increasing as the transition length decreases with increasing Reynolds number. The light aircraft design space is found to be multi-modal, with the optimization framework producing two distinct local minima. Transonic drag minimizations demonstrate that the optimization framework can successfully trade a decrease in viscous drag with an increase in wave drag, and an infinite swept wing optimization demonstrates that the framework can delay both Tollmien-Schlichting and stationary crossflow instabilities.
Sequential Decision-making Under Uncertainty: Novel Methodologies and Applications
Keywords: Decomposition methods
Robust optimization
Sequential decision-making
Stochastic programming
Telecommunications

In sequential decision-making under uncertainty, multistage stochastic mixed-integer programming (MSMIP) is a tool for addressing optimization problems with a given probability distribution and the goal of optimizing a performance measure over a planning horizon. If there is no knowledge about the probability distribution, multistage adaptive robust optimization (MSARO) is a suitable modeling framework. The goal of this thesis is to expand the methodological aspects of these two techniques, and in turn their applications. First, we study MSMIP problems, which can be approximated by using certain policies, e.g., linear decision rules. However, directly applying this idea to problems with integer decisions is difficult. We introduce Lagrangian dual decision rules (LDDRs) for MSMIP that overcome this difficulty by applying decision rules in Lagrangian duals of the MSMIP. We propose two new bounding techniques based on stagewise and nonanticipative Lagrangian duals. Our proposal requires fewer assumptions than most existing MSMIP methods. Our numerical experiments demonstrate that the LDDR approaches yield significant optimality gap reductions compared to existing general-purpose bounding methods for MSMIP. Next, we consider two problems in telecommunications industry. Network service providers routinely allocate resources to incoming requests and recover under-utilized capacity. For this resource allocation/reallocation, we present the first two-stage stochastic programming models to maximize the expected throughput, and solve them by an efficient decomposition algorithm that benefits from their observed tight linear programming bound. Additionally, we model the provisioning problem by MSMIP and approach it by our LDDR methodology. Experiments on real backbone networks reveal the significant value of considering the often overlooked uncertainty. Lastly, for MSARO problems we design primal and dual bounding methods, originated from adaptation of two decision rules rooted in stochastic programming. Our framework approximates the primal and dual formulations of MSARO with two-stage models. We provide sufficient conditions under which the column-and-constraint generation can exactly solve the primal approximation. For the dual approximation, we present a monolithic bilinear program valid for continuous MSARO problems, and a cutting-plane method for mixed-integer cases. Computational experiments on newsvendor and location-transportation problems show that our bounds yield considerably smaller optimality gaps compared to the existing methods.
From Hospital to Home for Persons Living with Dementia and their Family Caregivers
Keywords: Aging
Care transition
Dementia
Family caregiver
Grounded theory
Meta ethnography

Older adults living with dementia are at risk for more complex health care transitions than individuals without this condition. The central research question guiding this thesis was: “How do older adults living with dementia and/or their caregivers experience and perceive the hospital-to-home care transition?” One study with three separate areas of inquiry was pursued. For Paper 1, a body of qualitative literature was systematically searched and synthesized using a meta-ethnography approach. The analysis revealed three categories: (1) feelings associated with the health care transition; (2) processes associated with the care transition; and (3) evaluation of the quality of care associated with the care transition. The objective of paper 2 sought to develop a theoretical understanding of the social processes engaged in by people with dementia and their family caregivers leading to and following a care transition to hospital and then home. A constructivist grounded theory was used, and a total of 25 people participated in 21 interviews. Study findings contribute to the dementia care transition literature by providing a conceptual framework that explains what family caregivers do (taking over), how they manage (connecting dots), and what they experience (rising up) following a care transition. Situated centrally is the core process, Seeing the day-to-day situation, which is characterized by caregivers as constant intermediaries between patients and the health system. In paper 3, a qualitative descriptive design was used to capture perceptions of quality home and community care for those living with dementia and their caregivers. Study findings found that supporting people with dementia to live in the community requires available, acceptable, adaptable and affordable home and community-based care services. Overall, this thesis demonstrates the complex nature of care transitions for those living with dementia and their caregivers. Compounding the already strained experience are perceived challenges in communication and care coordination processes, and an inadequately resourced and inflexible home and community care system.
Unpacking Emotion Regulation: Associations among Symptom Burden, Strategy Implementation Beliefs, and Strategy Usage
Keywords: beliefs
efficacy
effort
emotion regulation
symptom burden
symptoms

General beliefs concerning one’s capacity for emotion regulation (ER) influence the selection and implementation of regulatory strategies. For instance, depressive symptoms have been related to higher rates of ruminative thinking and lower rates of cognitive reappraisal. However, it is unclear how much people differ in strategy-specific ER beliefs, whether such variation in beliefs predicts differences in strategy implementation, and whether symptom burden is associated with this process. Three empirical studies were conducted to understand the associations of strategy-specific beliefs regarding implementation efficacy (the ability to successfully implement strategies) and effort (the motivational cost of implementing strategies), the moderating effect of symptom burden, and post-regulation appraisals of strategy efficacy and overall regulation effectiveness (whether the strategies collectively worked to reduce negative emotions). Study 1 (n = 128) revealed that strategy-specific beliefs of implementation effort predicted lower overall strategy usage in response to emotional stressors presented in a lab setting. However, no association was detected between implementation efficacy beliefs and strategy usage. Findings from Study 2 (n = 130) showed that symptom burden predicted lower efficacy but had no relation to effort beliefs, and the interactions between symptom burden and implementation beliefs did not predict strategy usage following an emotional stressor. However, in real-world settings, Study 3 (n = 240) demonstrated that strategy-specific efficacy beliefs positively predicted strategy usage. Here, symptom burden also interacted with implementation efficacy beliefs in predicting strategy usage: those with higher symptom burden showed a stronger relationship between implementation efficacy beliefs and strategy usage. Moreover, higher symptom burden was also related to higher appraisals of strategy efficacy but lower overall regulation effectiveness, potentially blunting reinforcement of adaptive strategy selection. Together, this work underscores the role of strategy-specific implementation beliefs for strategy usage across both lab and ecologically valid settings. These findings suggest that symptom burden makes it more likely for individuals to use strategies based on their implementation beliefs while perceiving strategies as less successfully implemented, which could have meaningful implications for the clinical treatment of psychological disorders.
Droplet Formation in Simple Nonlocal Aggregation Models
Keywords: Aggregation
Calculus of variations
Concentration compactness
Interaction energy

We study interaction energies given by various kernels, and investigate how these kernels drive the formation of multiple flocks within a larger population. We show that for a class of kernels having a ``well-barrier'' shape that the energy is minimized by a sequence of indicators of finitely many balls whose supports move further and further apart. The dichotomy case of the concentration compactness principle is a key ingredient in our proof. To better understand the underlying geometry and the role of the height and width of the repulsive barrier, we also consider a toy model which forbids points in the support of an admissible density from being within a certain range of distances from one another. We show in one dimensions, that no matter the width of this range the energy is minimized by the indicator of a union of well separated intervals of equal length and one smaller interval, however other minimizers are possible. Finally, we also consider weakly repulsive kernels and show that Wasserstein $d_{\infty}$ local minimizers must saturate the density constraint.
Time-resolved Electron and Serial X-Ray Crystallography of PbS Quantum Dots and Biomolecules
Keywords: Electron-Phonon Interactions
Fixed-Target Serial Femtosecond Crystallography
Semiconductor Quantum Dots
Ultrafast Electron Diffraction

This thesis reports on the results of a series of crystallographic studies performed using ultrafast electron diffraction (UED) and serial X-ray crystallography on semiconductor nanocrystal and protein samples. In the first part of the thesis, ultrabright femtosecond electron pulses generated using a radio frequency-compressed photocathode electron source are employed to measure the photoinduced lattice response of lead sulfide (PbS) colloidal quantum dots following the optical generation of above-bandgap excitons. Short-range nonthermal lattice distortions are observed on the picosecond timescale in the form of exaggerated atomic disorder in the (100) crystallographic directions and deviations from a purely thermal response at short distance scales (< 12 Å). These structural changes are found to be related to surface charge trapping through size- and surface-series experiments and a pair distribution function analysis. In the second part of the thesis, a description of a new experimental scheme for serial X-ray crystallography is presented. The recent advent of free-electron lasers (XFEL) in the hard X-ray wavelength range (< 1 Å) has necessitated the use of serial femtosecond crystallography (SFX) for static and time-resolved structure determination. This has driven the innovation of novel sample delivery techniques to meet the stringent demands imposed by the SFX approach. This thesis outlines the development and implementation of a versatile high-speed fixed-target sample delivery technique based on a microfabricated silicon chip and spectroscopic sample mapping capability for use at both XFEL and synchrotron light sources. Application of the “serial crystallography chip” method maximizes hit-rates and minimizes sample consumption, as demonstrated by crystallographic experiments on the proteins: carboxy-myoglobin, lysozyme and fluoroacetate dehalogenase. An extension of the method which combines fixed-target serial crystallography with conventional rotation crystallography is also presented, which allows for X-ray induced damage-free structures to be obtained using serial crystallography at synchrotron light sources.
Advanced Boundary Element Techniques for Multiregion and Multiscale Electromagnetic Modelling
Keywords: Boundary element method
Computational electromagnetics
Computational science
High-performance computing
Integral equations
Numerical methods

The rapidly increasing complexity of electronic hardware, such as integrated circuits and advanced electromagnetic surfaces, tends quickly to outgrow the capabilities of existing electromagnetic simulation tools. For example, complex chip- and package-level interconnect networks require broadband full-wave simulations that capture electromagnetic fields both inside and outside each object in the structure, including skin effect in conductors. The boundary element method has emerged as an appealing modelling technique because it allows solving three-dimensional problems using a two-dimensional surface mesh. However, existing boundary element formulations are limited in their robustness, efficiency, and scalability for modelling systems which are multiscale (i.e., extreme variations in size, frequency, and possibly material properties) and multiregion (i.e., structures involving penetrable objects). In particular, key challenges include a limited ability to handle large structures, a poor trade-off between robustness and efficiency, and numerical instability at low frequencies. In this thesis, new surface integral formulations are developed to meet these challenges in a scalable, rigorous, and accurate manner. The new frontier of potential-based integral equations is explored to develop a multiregion boundary element formulation capable of modelling interconnects accurately over an unprecedented frequency range. Realistic numerical examples drawn from various applications demonstrate progress towards alleviating some of the core challenges in multiscale and multiregion electromagnetic modelling.
The Sword of the Immanent God: Heinrich Heine’s Sensualist Style
Keywords: Embodiment
Heinrich Heine
Movement
Pantheism
Sensualism
Style

In classified communications surrounding the notorious ban on the junges Deutschland, the officials responsible single out Heinrich Heine’s essay Zur Geschichte der Religion und Philosophie in Deutschland, claiming that it threatens the existing order partly because of the sensualist sociopolitical programme it promotes, which aims at a “Rehabilitiren der Materie” and its “Versöhnung mit dem Geiste,” but primarily because of the text’s style—which, the authorities suggest, somehow reflects its sensualist aims. Following up on this observation and corroborating indications from Heine himself and his readers, the present study explores the hitherto largely unexamined link between sensualism and style in the Essay.In doing so, the study focuses on a practical contribution the Essay is designed to make to its sensualist goals—goals which consist of suppressing two conceptions of God that oppose sensualism (spiritualism and deism), promoting a different notion of the divine that supports the sensualist programme (pantheism), and subsequently executing a sensualist revolution. The analysis of the practical contribution the Essay makes to its goals begins by extracting Heine’s general conception of that contribution, according to which it consists of the use of a material language to embody ideas so that they can move matter—a way of writing which reflects the sensualist aim to reconcile spirit and matter and is therefore termed the sensualist style. I then discuss each element of the sensualist style in detail, formulating a theory and then showing how that theory is reflected in the Essay’s own style: I argue that material language refers to a plastische way of writing consisting primarily of Figuren, the vivid representation of the sensory aspect of human beings; embodiment of thought, to the use of Figuren that constitute visible thoughts, sensory, bodily-material manifestations of ideas; and movement of matter, to the power such embodied ideas possess to affect the reader’s bodily behaviour, either drawing them towards or pushing them away from the embodied thought—which, in the Essay, is used to repel readers from a spiritualist or deist way of life and turn them into an avatar of pantheism.
Policing “Target People”: Crime Control and Political Repression in the People's Republic of China
Keywords: Authoritarian politics
Chinese politics
Drug policy
Policing
Political repression
Surveillance

How are political repression and crime control related in authoritarian states? And why do authoritarian states adapt their control apparatus? To answer these questions, this dissertation focuses on policing in the People’s Republic of China under the Hu Jintao (2002-2012) and Xi Jinping (2012-2022) administrations. Across both administrations, victims of political repression included dissidents, ethnic minorities, and petitioners. Yet, these were not the only targets of state control. China's police also surveilled, harassed, and detained former prisoners, users of drugs, and those with mental illnesses. Instead of dividing targets of political repression from targets of crime control, China’s police categorized a vast array citizens under a common label: “target people.” This dissertation is comprised of four thematically-linked chapters addressing two conceptual questions: how are political repression and crime control related in authoritarian states like China? And why do authoritarian states adapt their control apparatuses? In answering these two questions, this dissertation argues that state repression under the Hu and Xi administrations was defined by three broad trends: the conflation of crime control and political repression; police collaboration with other party-state organs to deepen control in the community; and the growing use of control mechanisms against the general public. By exploring these policing practices, this dissertation contributes to the literature on how authoritarian states govern and how their repressive apparatuses adapt.
Development of a Prototype High-power Ultrasound Phased-array System for the Treatment of Deep Vein Thrombosis
Keywords: High Intensity Focused Ultrasound
Sonothrombolysis
Ultrasound Transducers

Deep Vein Thrombosis (DVT) is the formation of thrombus in the deep veins of the body. The most important sequela of DVT, pulmonary embolism, is a major cause of mortality and morbidity due to the occlusion of the blood vessels in the lung. Common clinical treatments can provoke considerable consequences such as bleeding and damage to the vessel wall. It is well established that high-power ultrasound as a potentially non-invasive method can mechanically fragment the thrombus and restore the blood flow in the absence of lytic agents. Using single-element, focused transducers in most of these studies can lead to limitations such as lack of steerability and control of the focus. There is, therefore, a need for the development of high-power 2D phased-array transducers with the ability to electronically steer the beam with substantially shorter time delays to cover the whole target volume before the clot is released. This thesis presents the development of a novel high-pressure amplitude clinical transmit and receive array system for the treatment of DVT. We addressed the challenges associated with 2D fully steerable arrays such as high electrical impedance and element breakdown at high voltages, and then constructed a 64-element (8 × 8) high-power phased-array module operating at 260 kHz. The module elements generated 1.01±0.09 MPa at 2 mm distance while maintaining this pressure level over 10,000 sonication repetitions. Then, we modeled and constructed a 16-module cylindrical array system. The challenges associated with the large focal size of the low frequency ultrasound were surmounted with the design and a FWHM focal size (3.7 × 4.1 × 11.2 mm), and a pressure amplitude (34 MPa) suitable for DVT thrombolysis was achieved. In vitro experiments manifested a partial and complete clot breakdown at 11.5 and 15 MPa pressure at the focus. To complete the array system and qualify it for the clinical applications, we incorporated a receiver array (516 kHz) into the system. Modeling and testing of the receiver array demonstrated acceptable passive acoustic maps at different steering locations. Overall, the developed transmit-receive array system exhibited strong potential to be used in future in vivo and clinical treatments.