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Competing And Cooperating Orders In The Three-Band Hubbard Model: A Comprehensive Quantum Monte Carlo And Generalized Hartree-Fock Study, Adam Chiciak Jan 2020

Competing And Cooperating Orders In The Three-Band Hubbard Model: A Comprehensive Quantum Monte Carlo And Generalized Hartree-Fock Study, Adam Chiciak

Dissertations, Theses, and Masters Projects

Significant progress has been made in studying strongly correlated electronic systems with major focus on understanding high-temperature superconductivity. At the center of these studies are the so-called cuprates, which are characterized by a quasi-2D Copper-Oxide plane in which superconductivity is believed to arise. From the theoretical point of view, the complex electronic structure of these materials makes a fully ab initio many-body computation a formidable task, so we are forced to focus on minimal models that can reproduce the physics, the most well known of which is known as the Hubbard Model, which relies on the Zhang-Rice singet notion to ...


Single Image Direct-Global Illumination Separation, Zhaoliang Duan Jan 2020

Single Image Direct-Global Illumination Separation, Zhaoliang Duan

Dissertations, Theses, and Masters Projects

Global light transport, including diffuse interreflections, caustic, refractions and subsurface scattering, is important to achieve photorealistic rendering. However rendering these phenomena is very time-consuming. Furthermore, many inverse rendering methods’ accuracy in computer graphics and computer vision is adversely affected by the presence of global light transport. Therefore, separating direct-global light transport components is necessary to help in designing new rendering methods and in improving the accuracy of many image inverse methods. Prior work on separating direct and global light transport from photographs either requires expensive hardware, requires multiple photographs of the scene, or fails to accurately recover high frequency details ...


Experiments And Theory On Dynamical Hamiltononian Monodromy, Matthew Perry Nerem Jan 2020

Experiments And Theory On Dynamical Hamiltononian Monodromy, Matthew Perry Nerem

Dissertations, Theses, and Masters Projects

In classical mechanics, one of the advanced topics is the study of action and angle variables. These variables are quite abstract, but very powerful tools for describing classical motion. If a system has a full set of conservation laws, and if the motion of the system is bounded, then the motion can be described as flow on a torus. Action variables are functions of the conservation laws that identify the torus on which the motion lies, while angle variables tell the location of the system on that torus. In certain cases, the functional relationship between the conservation laws and the ...


Influence Of Suspended Particle Size And Composition On Particle Image Processing, Estuarine Floc Fractal Properties, And Resulting Estuarine Light Attenuation, Kelsey Fall Jan 2020

Influence Of Suspended Particle Size And Composition On Particle Image Processing, Estuarine Floc Fractal Properties, And Resulting Estuarine Light Attenuation, Kelsey Fall

Dissertations, Theses, and Masters Projects

Understanding the nature of suspended particles is crucial to explaining water clarity issues in many estuaries, including the Chesapeake Bay and its tidal tributaries. Typical near surface estuarine particles are not individual sediment grains, but rather are clusters of inorganic and organic components known as flocs. Because of their fragile nature, flocs are challenging to observe in-situ, so their influence on the optical properties of the system are not well-known. This dissertation used a combination of state-of-the-art optical instrumentation, including laser scattering and transmissometry, a high-definition particle imaging camera system (PICS), and irradiance meters, along with supporting laboratory analysis techniques ...


Growth Engineering And Characterization Of Vanadium Dioxide Films For Ultraviolet Detection, Jason Andrew Creeden Jan 2020

Growth Engineering And Characterization Of Vanadium Dioxide Films For Ultraviolet Detection, Jason Andrew Creeden

Dissertations, Theses, and Masters Projects

There is a need for efficient ultraviolet (UV) detectors in many fields, such as aerospace, automotive manufacturing, biology, environmental science, and defense, due to photomultiplier tubes (the currently available technology) often not meeting application constraints in weight, robustness, and power consumption. In my thesis, I demonstrate that high quality vanadium dioxide (VO2) thin films, epitaxially grown on niobium doped titanium dioxide substrates (TiO2:Nb), display a strong photoconductive response in the UV spectral range, making them promising candidates for photomultiplier-free UV photodetection. By adjusting the characteristics of the substrate and VO2 film, the samples achieve external quantum efficiency exceeding 100 ...


Wearable Technology For Healthcare And Athletic Performance, Amanda Annette Watson Jan 2020

Wearable Technology For Healthcare And Athletic Performance, Amanda Annette Watson

Dissertations, Theses, and Masters Projects

Wearable technology research has led to advancements in healthcare and athletic performance. Devices range from one size fits all fitness trackers to custom fitted devices with tailored algorithms. Because these devices are comfortable, discrete, and pervasive in everyday life, custom solutions can be created to fit an individual's specific needs. In this dissertation, we design wearable sensors, develop features and algorithms, and create intelligent feedback systems that promote the advancement of healthcare and athletic performance. First, we present Magneto: a body mounted electromagnet-based sensing system for joint motion analysis. Joint motion analysis facilitates research into injury prevention, rehabilitation, and ...


Pinpointing Software Inefficiencies With Profiling, Shasha Wen Jan 2020

Pinpointing Software Inefficiencies With Profiling, Shasha Wen

Dissertations, Theses, and Masters Projects

Complex codebases with several layers of abstractions have abundant inefficiencies that affect the performance. These inefficiencies arise due to various causes such as developers' inattention to performance, inappropriate choice of algorithms and inefficient code generation among others. To eliminate the redundancies, lots of work has been done during the compiling phase. However, not all redundancies can be easily detected or eliminated with compiler optimization passes due to aliasing, limited optimization scopes, and insensitivity to input and execution contexts act as severe deterrents to static program analysis. There are also profiling tools which can reveal how resources are used. However, they ...


Inorganic Carbon Chemistry In East Antarctic Coastal Polynyas, Mar C. Arroyo Jan 2020

Inorganic Carbon Chemistry In East Antarctic Coastal Polynyas, Mar C. Arroyo

Dissertations, Theses, and Masters Projects

Polynyas are large areas of open water or reduced sea ice coverage that persistently form in polar environments and often experience enhanced rates of physical, chemical, and biological processes that impact ocean dynamics on local to global scales. Polynyas that form adjacent to the coast, known as coastal polynyas, play an important role in the global carbon cycle by regulating the exchange of CO2 between the ocean and atmosphere in the high latitudes. Because of their importance to the global carbon cycle, there is a particular interest to better characterize CO2 system processes in Antarctic coastal polynyas. In this study ...


Motion Sensors-Based Human Behavior Recognition And Analysis, Hongyang Zhao Jan 2020

Motion Sensors-Based Human Behavior Recognition And Analysis, Hongyang Zhao

Dissertations, Theses, and Masters Projects

Human behavior recognition and analysis have been considered as a core technology that can facilitate a variety of applications. However, accurate detection and recognition of human behavior is still a big challenge that attracts a lot of research efforts. Among all the research works, motion sensors-based human behavior recognition is promising as it is low cost, low power, and easy to carry. In this dissertation, we use motion sensors to study human behaviors. First, we present Ultigesture (UG) wristband, a hardware platform for detecting and analyzing human behavior. The hardware platform integrates an accelerometer, gyroscope, and compass sensor, providing a ...


Dietary Monitoring Through Sensing Mastication Dynamics, Shuangquan Wang Jan 2020

Dietary Monitoring Through Sensing Mastication Dynamics, Shuangquan Wang

Dissertations, Theses, and Masters Projects

Unhealthy dietary habits (such as eating disorders, eating too fast, excessive energy intake, and chewing side preference) are major causes of some chronic diseases, including obesity, heart disease, digestive system disease, and diabetes. Dietary monitoring is necessary and important for patients to change their unhealthy diet and eating habits. However, the existing monitoring methods are either intrusive or not accurate enough. In this dissertation, we present our efforts to use wearable motion sensors to sense mastication dynamics for continuous dietary monitoring. First, we study how to detect a subject's eating activity and count the number of chews. We observe ...


Temporal Variability In Cohesive Sediment Dynamics In A Partially Mixed Estuary, The York River Estuary, Virginia, Usa: A Numerical Study Developed From Observations, Danielle Tarpley Jan 2020

Temporal Variability In Cohesive Sediment Dynamics In A Partially Mixed Estuary, The York River Estuary, Virginia, Usa: A Numerical Study Developed From Observations, Danielle Tarpley

Dissertations, Theses, and Masters Projects

Fine-grained material such as silts and clays are the predominant sediment type in low energy systems such as micro-tidal embayments and estuaries. Due to its cohesive nature, fine sediment typically moves through marine systems as aggregated particles, or flocs, rather than as individual mineral grains. The particle's components, local hydrodynamics, and concentration influence floc size, density, and fall velocity. These, in turn, impact suspended sediment transport, which complicates predictions of the fate of sediment for water quality, contaminant distribution, and dredging purposes in these systems. This dissertation used a state-of-the-art modeling system and observations to examine the variability in ...


Hardware-Assisted Security Mechanisms On Arm-Based Multi-Core Processors, Shengye Wan Jan 2020

Hardware-Assisted Security Mechanisms On Arm-Based Multi-Core Processors, Shengye Wan

Dissertations, Theses, and Masters Projects

During the last decade, Trusted Execution Environment (TEE) provided by ARM TrustZone had become one of the most popular techniques to build security on mobile devices. On a TrustZone-enabled system, the software can execute in either Secure World (trusted) and Normal World (untrusted). Meanwhile, along with the expeditious development of TrustZone technology, the security of TEE is also challenged by dealing with more and more on-board hardware and in-TEE applications. In this dissertation, we explicitly study the security of ARM TrustZone technology with the latest ARM architecture in three aspects. First, we study the security of the TrustZone-assisted asynchronous introspection ...


Understanding Performance Inefficiencies In Native And Managed Languages, Pengfei Su Jan 2020

Understanding Performance Inefficiencies In Native And Managed Languages, Pengfei Su

Dissertations, Theses, and Masters Projects

Production software packages have become increasingly complex with millions of lines of code, sophisticated control and data flow, and references to a hierarchy of external libraries. This complexity often introduces performance inefficiencies across software stacks, making it practically impossible for users to pinpoint them manually. Performance profiling tools (a.k.a. profilers) abound in the tools community to aid software developers in understanding program behavior. Classical profiling techniques focus on identifying hotspots. The hotspot analysis is indispensable; however, it can hardly diagnose whether a resource is being used in a productive manner that contributes to the overall efficiency of a ...


Deep Learning In Software Engineering, Cody Watson Jan 2020

Deep Learning In Software Engineering, Cody Watson

Dissertations, Theses, and Masters Projects

Software evolves and therefore requires an evolving field of Software Engineering. The evolution of software can be seen on an individual project level through the software life cycle, as well as on a collective level, as we study the trends and uses of software in the real world. As the needs and requirements of users change, so must software evolve to reflect those changes. This cycle is never ending and has led to continuous and rapid development of software projects. More importantly, it has put a great responsibility on software engineers, causing them to adopt practices and tools that allow ...


Design And Analysis Of Memory Management Techniques For Next-Generation Gpus, Haonan Wang Jan 2020

Design And Analysis Of Memory Management Techniques For Next-Generation Gpus, Haonan Wang

Dissertations, Theses, and Masters Projects

Graphics Processing Unit (GPU)-based architectures have become the default accelerator choice for a large number of data-parallel applications because they are able to provide high compute throughput at a competitive power budget. Unlike CPUs which typically have limited multi-threading capability, GPUs execute large numbers of threads concurrently to achieve high thread-level parallelism (TLP). While the computation of each thread requires its corresponding data to be loaded from or stored to the memory, the key to supporting the high TLP of GPUs lies in the high bandwidth provided by the GPU memory system. However, with the continuous scaling of GPUs ...


Filling In The Gaps: Applications Of Deep Learning, Satellite Imagery, And High Performance Computing For The Estimation And Distribution Of Geospatial Data, Seth Goodman Jan 2020

Filling In The Gaps: Applications Of Deep Learning, Satellite Imagery, And High Performance Computing For The Estimation And Distribution Of Geospatial Data, Seth Goodman

Dissertations, Theses, and Masters Projects

Many regions around the world suffer from a lack of authoritatively-collected data on factors critical to understanding human well-being. This challenges our ability to understand the progress society is making towards reducing poverty, improving lifespans, or otherwise improving livelihoods. A growing body of research is exploring how deep learning algorithms can be used to produce novel estimates of sparse development data, and how access to such data can impact development efforts. This dissertation contributes to this literature in three parts. First, using Landsat 8 satellite imagery and data from the Armed Conflict Location & Event Data Project, convolutional neural networks are ...


Study Of Scalar Extensions For Physics Beyond The Standard Model, Marco Antonio Merchand Medina Jan 2020

Study Of Scalar Extensions For Physics Beyond The Standard Model, Marco Antonio Merchand Medina

Dissertations, Theses, and Masters Projects

In this thesis we investigate the phenomenology of beyond the Standard Model scenarios with extra scalar fields. A review and motivation of extended electroweak symmetry breaking is presented. Then we address observational evidence of new physics such as possible lepton flavor violating processes and the relic abundance of dark matter by implementing models with three Higgs doublets. The complementarity between theoretical restrictions and experimental bounds on some of the predicted signals is leveraged to sharpen the allowed parameter space. After that we study embeddings of two-Higgs doublets into the Randall-Sundrum model with emphasis on the scalar fluctuations of the metric ...


Development Of Quantum Information Tools Based On Multi-Photon Raman Processes In Rb Vapor, Nikunjkumar Prajapati Jan 2020

Development Of Quantum Information Tools Based On Multi-Photon Raman Processes In Rb Vapor, Nikunjkumar Prajapati

Dissertations, Theses, and Masters Projects

Multi-photon nonlinear processes in atoms have served as important tools for quantum metrology, quantum communications, and quantum sensing. In this thesis, we experimentally address the interplay of various multi-photon Raman processes in hot Rb vapor, with the four-wave mixing (FWM) process being a central theme. FWM is the nonlinear response of a medium to a strong optical pump field inelastically scattering off atomic resonances and resulting in the generation of additional photons in different modes. FWM is a detrimental, but inherent part of electromagnetically induced transparency (EIT) and Raman based quantum memories. However, we were able to weaken the four-photon ...


The Role Of Suspended Sediment In Assessing Coastal Wetland Vulnerability, Daniel J. Coleman Jan 2020

The Role Of Suspended Sediment In Assessing Coastal Wetland Vulnerability, Daniel J. Coleman

Dissertations, Theses, and Masters Projects

Coastal wetlands sequester carbon, attenuate waves and storm surge, filter out nutrients and pollutants, and act as nursery habitat for important fisheries. The value of these ecosystems is underscored by their vulnerability to climate change, especially sea level rise. To persist under the threat of rising sea level, coastal wetlands must build elevation vertically. Delivery of sediment to the marsh during tidal flooding is a key component in the ecogeomorphic feedbacks that lead to elevation gain. Despite the importance of suspended sediment to assessing coastal wetland vulnerability, many questions remain unanswered. This dissertation addresses the impact of suspended sediment concentration ...


Copper(I) Iodide-Based Chemical Sensor Materials In Gaseous And Aqueous Media, Matthew D. Kessler Jan 2020

Copper(I) Iodide-Based Chemical Sensor Materials In Gaseous And Aqueous Media, Matthew D. Kessler

Dissertations, Theses, and Masters Projects

Chemical detection is an area of great importance in the shift to more green approaches to industry. Some of the chemical species produced by assorted industries can be harmful, long lived, and challenging to differentiate. Copper(I) iodide (CuI) is a material that readily forms complexes of multiple colors, both under visible and ultraviolet (UV) light. The process of CuI reacting with dimethyl sulfide vapor to produce a color change (vapochromism) has been analyzed to propose mechanistic information about the process. Using the information obtained, a series of potential sensor materials were developed with CuI as the base. The complexes ...


Insulator To Metal Transition Dynamics Of Vanadium Dioxide Thin Films, Scott Madaras Jan 2020

Insulator To Metal Transition Dynamics Of Vanadium Dioxide Thin Films, Scott Madaras

Dissertations, Theses, and Masters Projects

Vanadium Dioxide (VO2) is a strongly correlated material which has been studied for many decades. VO2 has been proposed for uses in technologies such as optical modulators, IR modulators, optical switches and Mott memory devices. These technologies are taking advantage of VO2’s insulator to metal transition (IMT) and the corresponding changes to the optical and material properties. The insulator to metal transition in VO2 can be accessed by thermal heating, applied electric field, or ultra-fast photo induced processes. Recently, thin films of VO2 grown on Titanium Dioxide doped with Niobium (TiO2:Nb), have shown promise as a possible UV ...


Exploring Heterogeneous Architectures With Tools And Applications, Du Shen Jan 2020

Exploring Heterogeneous Architectures With Tools And Applications, Du Shen

Dissertations, Theses, and Masters Projects

Heterogeneous architectures have become popular due to programming flexibility and energy efficiency. Heterogeneous architectures include GPU accelerators, and memory subsystems consisting fast and slow components. Achieving high performance for programs running on heterogeneous architectures requires sophisticated tools and applications. They either lack hardware support for fast memory component, or provide complex programming model, which puts extra burdens on compilers and programmers. However, existing tools either rely on simulators or lack support across different GPU architectures, runtime or driver versions. Thus, they only provide insufficient insights. In the first project, we develop DataPlacer, a profiling tool to provide guidance for data ...


A First-Principles Study Of The Nature Of The Insulating Gap In Vo2, Christopher Hendriks Jan 2020

A First-Principles Study Of The Nature Of The Insulating Gap In Vo2, Christopher Hendriks

Dissertations, Theses, and Masters Projects

Upon cooling past a critical temperature Tc = 340 K Vanadium dioxide (VO2) exhibits a metal-insulator transition (MIT) from a metallic rutile R to an insulating monoclinic M1 phase. Other insulating phases, a monoclinic M2 and triclinic T, have been identifed and are accessible via strain or doping. Despite decades of research, the nature of the VO2 MIT is still not fully understood. In this work we present ab-initio hybrid density functional theory (DFT) calculations on the insulating phases, compare the results to experimental measurements and discuss their implications on our understanding of the VO2 MIT. Recent measurements on M1 VO2 ...


Spatial And Temporal Distribution Of Phycotoxins In Lower Chesapeake Bay: Method Development And Application, Michelle D. Onofrio Jan 2020

Spatial And Temporal Distribution Of Phycotoxins In Lower Chesapeake Bay: Method Development And Application, Michelle D. Onofrio

Dissertations, Theses, and Masters Projects

Harmful algae can illicit adverse effects on aquatic and human health through various mechanisms, including through the production of bioactive compounds called phycotoxins. In the Chesapeake Bay, the largest estuary in the United States, little information was known about the distribution of phycotoxins, even though this region is known to harbor 37+ different species of harmful algae. Due to the presence of multiple species that can produce distinct groups of phycotoxins, a multi-toxin approach was taken to study this region. Two methods for the quantification of 13 phycotoxins (microcystin-RR, -LR, YR, azaspiracid-1, -2, karlotoxin 3, goniodomin A, yessotoxin, brevetoxin-2, pectenotoxin-2 ...


Environmental Controls On Pteropod Ecology And Physiology Along The Western Antarctic Peninsula, Patricia Susan Thibodeau Jan 2020

Environmental Controls On Pteropod Ecology And Physiology Along The Western Antarctic Peninsula, Patricia Susan Thibodeau

Dissertations, Theses, and Masters Projects

Pteropods (pelagic snails) are ubiquitous zooplankton in the Southern Ocean and abundant along the Western Antarctic Peninsula (WAP), one of the most rapidly warming regions on the planet. They are important prey for higher trophic levels, grazers of phytoplankton, and contribute to particulate organic and inorganic carbon export. Pteropods are heralded as bioindicators of ecosystem health due to the vulnerability of their aragonitic shells under ocean acidification conditions, which could greatly affect their abundances in the future. Despite their importance within Antarctic food webs, few studies have analyzed the effects of climate change on pteropod physiology and biogeography in the ...


Impacts Of Physical Transport On Estuarine Phytoplankton Dynamics And Harmful Algal Blooms, Qubin Qin Jan 2019

Impacts Of Physical Transport On Estuarine Phytoplankton Dynamics And Harmful Algal Blooms, Qubin Qin

Dissertations, Theses, and Masters Projects

The spatial and temporal variability of phytoplankton biomass in estuaries is determined by both local processes and transport processes. Local processes include biological processes (e.g., photosynthesis, respiration/excretion, and grazing) and settling, whereas transport processes include advective and diffusive transports. Transport processes have been demonstrated to regulate phytoplankton dynamics significantly by distributing both phytoplankton and other dissolved and particulate substances (e.g., nutrients, salts, sediments, and chromophoric dissolved organic matter). Yet, these transport properties lack a framework that unifies the pieced description of their various effects, and quantification of their importance under various environmental conditions. This dissertation highlights the ...


Partitioning Of Hydrophobic Organic Contaminants And Microbial Communities On Microplastics, Kelley Ann Uhlig Jan 2019

Partitioning Of Hydrophobic Organic Contaminants And Microbial Communities On Microplastics, Kelley Ann Uhlig

Dissertations, Theses, and Masters Projects

Microplastic contamination of aquatic environments has only recently caught the attention of scientists, regulators and the public. Microplastics are typically more recalcitrant than naturally occurring polymers and so have the potential to cause a range of issues, including increased exposure of marine life to chemical contaminants sorbed to or leached from microplastics, negative impacts due to ingestion of microplastics by biota, and the potential to carry and transport pathogenic and invasive species long distances. Bio-based, bio-degradable polymers have begun to gain market share as an alternative to traditional petrochemical-based plastics, but not much is known about their impacts in marine ...


On Enhancing Security Of Password-Based Authentication, Yue Li Jan 2019

On Enhancing Security Of Password-Based Authentication, Yue Li

Dissertations, Theses, and Masters Projects

Password has been the dominant authentication scheme for more than 30 years, and it will not be easily replaced in the foreseeable future. However, password authentication has long been plagued by the dilemma between security and usability, mainly due to human memory limitations. For example, a user often chooses an easy-to-guess (weak) password since it is easier to remember. The ever increasing number of online accounts per user even exacerbates this problem. In this dissertation, we present four research projects that focus on the security of password authentication and its ecosystem. First, we observe that personal information plays a very ...


Extraction And Parametrization Of Isobaric Trinucleon Elastic Cross Sections And Form Factors, Scott Kevin Barcus Jan 2019

Extraction And Parametrization Of Isobaric Trinucleon Elastic Cross Sections And Form Factors, Scott Kevin Barcus

Dissertations, Theses, and Masters Projects

By mining data from Jefferson Lab Hall A experiment E08-014 a new measurement of the 3He elastic cross section at Q^2 ≈ 34 fm^−2 was extracted from a large quasielastic background. This new data point falls approximately halfway between the first and second diffractive minima of the 3He form factors. When combined with recent high Q^2 3He elastic cross section measurements from JLab this new point improves our knowledge of the cross section and form factors at large momentum transfers. The new high Q^2 data motivate a reanalysis of the 3He elastic cross section world data and ...


Interfacial Forces Of 2d Materials At The Oil–Water Interface, William Winsor Dickinson Jan 2019

Interfacial Forces Of 2d Materials At The Oil–Water Interface, William Winsor Dickinson

Dissertations, Theses, and Masters Projects

Two-dimensional (2D) materials, including graphene and graphene oxide (GO), are a subject of interest for many researchers due to their exceptional properties (strength, conductivity, etc.). These materials, comprised of atomically-thin sheets, may naturally occur stacked together like sheets of paper, but their most interesting properties emerge when separated into individual layers. However, scaling up the processes used to isolate single sheets of some of these materials, particularly graphene, has proven problematic. They can be fiercely resistant to exfoliation, difficult to disperse, and have a worrying propensity to restack. All these problems contribute to the great difficulty these fascinating materials have ...