Physical Sciences and Mathematics Commons^™

Bayesian Spatiotemporal Modeling With Gaussian Processes, Qing He

Electronic Theses and Dissertations, 2020-2023

Bayesian spatiotemporal models have been successfully applied to various fields of science, such as ecology and epidemiology. The complicated nature of spatiotemporal patterns can be well represented through priors such as Gaussian processes. This dissertation is focused on two applications of Bayesian spatiotemporal models: a) anomaly detection for spatiotemporal data with missingness and b) zero-inflated spatiotemporal count data analysis. Missingness in spatiotemporal data prohibits anomaly detection algorithms from learning characteristic rules and patterns due to the lack of most data. This project is motivated by a challenge provided by the National Science Foundation (NSF) and the National Geospatial-Intelligence Agency (NGA). …

Observation Of Anisotropic Properties In Topological Quantum Materials, Gyanendra Dhakal

Electronic Theses and Dissertations, 2020-2023

The discovery of the three-dimensional topological insulator (TI) has enormously impacted our understanding of quantum materials. These novel materials are characterized by the topology rather than some order parameters. The TIs are the materials that exhibit insulating properties in the bulk while possessing the metallic state on the surface. These surface states are protected by time-reversal symmetry; as a result, the electrons featuring surface states are spin-polarized. After the discovery of TIs, other topological semimetallic (TSM) states were discovered, which enhanced the understanding and widened the reach of topological materials. Discoveries of various topological phases such as Dirac, Weyl, nodal …

Towards Secure And Trustworthy Iot Systems, Lan Luo

Electronic Theses and Dissertations, 2020-2023

The boom of the Internet of Things (IoT) brings great convenience to the society by connecting the physical world to the cyber world, but it also attracts mischievous hackers for benefits. Therefore, understanding potential attacks aiming at IoT systems and devising new protection mechanisms are of great significance to maintain the security and privacy of the IoT ecosystem. In this dissertation, we first demonstrate potential threats against IoT networks and their severe consequences via analyzing a real-world air quality monitoring system. By exploiting the discovered flaws, we can impersonate any victim sensor device and polluting its data with fabricated data. …

A Human-Centered Approach To Improving Adolescent Online Sexual Risk Detection Algorithms, Afsaneh Razi

Electronic Theses and Dissertations, 2020-2023

Computational risk detection has the potential to protect especially vulnerable populations from online victimization. Conducting a comprehensive literature review on computational approaches for online sexual risk detection led to the identification that the majority of this work has focused on identifying sexual predators after-the-fact. Also, many studies rely on public datasets and third-party annotators to establish ground truth and train their algorithms, which do not accurately represent young social media users and their perspectives to prevent victimization. To address these gaps, this dissertation integrated human-centered approaches to both creating representative datasets and developing sexual risk detection machine learning models to …

Physics And Applications Of Space-Time Wave Packets, Murat Yessenov

Electronic Theses and Dissertations, 2020-2023

Space-time wave packets (STWP) constitute a broad class of pulsed optical fields that are rigidly transported in linear media without diffraction or dispersion, and are therefore propagation-invariant in absence of optical nonlinearities or waveguiding structures. Such wave packets exhibit unique characteristics, such as controllable group velocities in free space and exotic refractive phenomena. At the root of these behaviors is a fundamental feature underpinning STWP: their spectra are not separable with respect to the spatial and temporal degrees of freedom. Indeed, the spatio-temporal structure is endowed with angular dispersion, in which each spatial frequency is associated with a single prescribed …

Reverse Engineering Of Adversarial Samples By Leveraging Patterns Left By The Attacker, Rahul Ambati

Electronic Theses and Dissertations, 2020-2023

Intrinsic susceptibility of deep learning to adversarial examples has led to a plethora of attack techniques with a common broad objective of fooling deep models. However, we find slight compositional differences between the algorithms achieving this objective. These differences leave traces that provide important clues for attacker profiling in real-life scenarios. Inspired by this, we introduce a novel problem of 'Reverse Engineering of aDversarial attacks' (RED). Given an adversarial example, the objective of RED is to identify the attack used to generate it. Under this perspective, we can systematically group existing attacks into different families, leading to the sub-problem of …

Optimal Impulse Controls With Changing Running Cost And Applications In Mortgage Refinance, Yuchen Cao

Electronic Theses and Dissertations, 2020-2023

Almost all home buyers have mortgages and it is quite common to have mortgage refinanced. There are two main reasons that make people decide to refinance the mortgage: (i) need some cash for urgent purposes, and (ii) lower the monthly payment. In this dissertation, we are not going to discuss (i), and we are investigating problems related to (ii). To begin with, let us intuitively make the following observations: If the interest rate remains the same as the current mortgage interest rate, then the monthly payment will automatically lower if you start a new mortgage with the same term, say, …

Application Of Biologically Activate Carbon For Treatment Of Sulfide-Laden Groundwater, Jessica Cormier

Electronic Theses and Dissertations, 2020-2023

Small-system water purveyors must overcome many challenges to provide an adequate and safe water supply to its consuming public. This dissertation reports on research related to the application of biologically activated carbon (BAC) media filters for the treatment of well water to remove disinfection by-product (DBP) precursor matter, measured as dissolved organic carbon (DOC), at two treatment plants serving a small community water system. Four research questions were investigated individually in discrete, yet interconnected studies at two water treatment facilities processing groundwater that contained hydrogen-sulfide (~1.2 mg/L) and dissolved organic carbon (~2.0 mg/L). The first study revealed that BAC filters …

Reticular Design And Synthesis Of Metal-Organic Frameworks With Targeted Emergent Properties, David Fairchild

Electronic Theses and Dissertations, 2020-2023

The research presented in this dissertation describes the design and synthesis of substitutional-solid-solution-based multivariate metal-organic frameworks (SSS-based MTV MOFs) with functionalized organic linkers to study their emergent properties in the crystalline solid state. The synthetic versatility and tunability of organic chemistry coupled with the predictable organization of inorganic structures enables MTV MOF systems to further the fundamental understanding of structure-composition-property relationships for the targeted design of applied materials due to their ability to control the structure, composition, and property independently. To begin, a set of terphenyl linkers with varied steric and electronic properties were crystallized as a family of UiO-type …

Terahertz Spintronics With Antiferromagnetic Insulators, Gyan Khatri

Electronic Theses and Dissertations, 2020-2023

The existence of the THz gap in the electromagnetic spectrum is not only preventing the advancement of several technologies but also hindering research and developmental activities due to a lack of research facilities operating in the gap region. There is a plethora of materials with dynamics lying in the THz gap region whose study could potentially lead to the development of new technologies for the generation, detection, and processing of THz signals. Antiferromagnets are gaining recent interest due to their high frequency dynamics lying in the THz region, and their potential uses as active elements in THz spintronics devices have …

Volume Bragg Gratings With Complex Phase Structures: A Three-Dimensional Foundation For Laser-Beam Engineering, Lam Mach

Electronic Theses and Dissertations, 2020-2023

Bragg diffraction is a natural phenomenon that arises from the coherent interference of scattered waves in multilayer structures with a well-defined periodicity. In practice, the physical size of these multilayer structures varies depending on the intended application, from micrometer-thick dielectric mirrors with tens of layers to centimeter-long Bragg gratings with ten-thousands of layers. The scope of this work centers around a unique class of multilayer elements developed in bulk photo-thermo-refractive (PTR) glass – the volume Bragg grating (VBG). The content of this thesis places an emphasis on the volume nature of these Bragg devices, implying a three-dimensional structure whereupon arbitrary …

Load Forecasting And Synthetic Data Generation For Smart Home Energy Management System, Mina Razghandi

Electronic Theses and Dissertations, 2020-2023

A number of recent trends, such as the increased power consumption in developed and developing countries, the dangers associated with greenhouse gases, the potential shortages of fossil fuels, and the increasing availability of solar and wind energy act as motivating factors for the development of more intelligent and efficient systems both on the power provider as well as the consumer side. One of the most important prerequisites for making efficient energy management decisions is the ability to predict energy production and consumption patterns. While long-term forecasting of average consumption had been extensively used to direct investments in the energy grid, …

Imaging Based Beam Steering For Optical Communication And Lidar Applications, Sajad Saghaye Polkoo

Electronic Theses and Dissertations, 2020-2023

Optical beam steering is a key component in any application that requires dynamic (i.e. realtime control) of beam propagation through free-space. Example applications include remote sensing, spectroscopy, laser machining, targeting, Lidar, optical wireless communications (OWC) and more. The pointing control requirements for many of these applications can be met by traditional mechanical steering techniques; however, these solutions tend to be bulky, slow, expensive, power hungry and prone to mechanical failures leading to short component lifetimes. Two emerging applications, Lidar imaging and OWC, truly need improved beam-steering capabilities to flourish and support the advancement of self-driving cars or relieve the congestion …

Design Of A High-Power Terahertz Emitter Array Using A High-Temperature Superconductor, Ruqayyah Shouk

Electronic Theses and Dissertations, 2020-2023

By applying a dc voltage V across the stack of intrinsic Josephson junctions naturally present in the high-temperature superconductor consisting of two parts bismuth, two parts strontium, one part calcium, two parts copper, and a bit more than eight parts oxygen, several groups have been able to obtain coherent THz emission at output powers in the µW range. In order to enhance the output power well into the mW range suitable for many applications, we have studied a compact design of a stand-alone mesa array with gold layers on the top and bottom of the superconductor. In this design, an …

A Novel Antibody-Dependent Mc-Lr Detecting Biosensor For Early Warning Of Harmful Algal Blooms (Habs), Stephanie Stoll

Electronic Theses and Dissertations, 2020-2023

Microcystins (MCs) are toxins produced by cyanobacteria commonly found in harmful algal blooms (HAB) occurring in many surface waters. Due to their toxicity to humans and other organisms, the World Health Organization (WHO) set a guideline of 1 µg/L for microcystin-leucine-arginine (MC-LR) in drinking water. However, current analytical techniques for the detection of MC-LR such as liquid chromatography-mass spectrometry (LC-MS) and enzyme-linked immunosorbent assay (ELISA) are costly, bulky, time-consuming, and mostly conducted in a laboratory, requiring highly trained personnel. Therefore, an analytical method that can be used in the field for rapid determination is essential. In this study, an Anti-MC-LR/MC-LR/Cysteamine …

Development Of A Computational Application To Aid With Chemometric And Forensic Analysis Of Fire Debris Samples, Michelle Corbally

Electronic Theses and Dissertations, 2020-2023

Fire debris analysis is a forensic science discipline that determines if an ignitable liquid residue is present or absent in a fire debris sample. Currently, fire debris analysis results in categorical statements based on qualitative data, not the quantitative evidentiary value of data. The purpose of this research was to develop a novel software application to aid fire debris analysts in the identification and classification of ignitable liquid residues that are found in fire debris samples. The developed application uses target factor analysis (TFA) and Pearson correlation for compound identification in gas chromatograms using mass spectral comparison and allows for …

Raman Excitation Laser Effects On Peak Parameters And Peak Metamorphic Temperatures Of Primitive Carbonaceous Chondrites, Amy Lebleu-Debartola

Electronic Theses and Dissertations, 2020-2023

MicroRaman (µRaman) spectroscopy is often regarded as a non-destructive technique, utilized to analyze limited materials, both terrestrial and extraterrestrial. Carbonaceous chondrite meteorites are of particular interest but they are dark (low albedo) materials, and thus absorb the majority of incident visible light. Raman excitation lasers can induce considerable localized heating, even when low laser powers are used. It has been previously suggested to utilize low power lasers of =0.4 mW to minimize damaging carbonaceous samples in several fields, including Meteoritics, Geology, Chemistry, and Paleontology. Peak Metamorphic Temperatures (PMT) experienced by the meteorite can be estimated from Raman fitting parameters related …

Towards Automated Data Mining: Reinforcement Intelligence For Self-Optimizing Feature Engineering, Kunpeng Liu

Electronic Theses and Dissertations, 2020-2023

Feature engineering is one of the most important components in data mining and machine learning. One of the key thrusts in data mining is to answer: How should a low-dimensional geometry structure be extracted and reconstructed from high-dimensional data? To solve this issue, researchers proposed feature selection, PCA, sparsity regularization, factorization, embedding, and deep learning. However, existing techniques are limited in achieving full automation, globally optimal, and explainable explicitness. Can I address the automation, optimal, and explainability challenges in data geometry reconstruction? A low-dimensional data geometry structure is crucial for SciML methods (e.g., GP models), and the accuracy of these …

"Reeling In" Juvenile Sportfish Through Coastal Habitat Restoration: Population, Community, And Trophic Responses In The Indian River Lagoon, Florida, Jennifer Loch

Electronic Theses and Dissertations, 2020-2023

Coastal habitats provide crucial nursery habitat for predatory fishes, but they are in decline worldwide, impacting economically important fisheries. Habitat restoration can simultaneously mitigate the effects of habitat loss and benefit predators (e.g., sportfish), although this relationship is understudied. Here, the response of juvenile sportfish to oyster reef and living shoreline restoration is compared to controls in the Indian River Lagoon, Florida prior to and following restoration for up to three years through examination of community (diversity, assemblage), population (abundance), biometric (size, body condition), ontogenetic, and trophic (gut contents, stable isotopes) dynamics. Stable isotopes were used to quantify dietary history, …

Development Of Holographic Phase Masks For Wavefront Shaping, Nafiseh Mohammadian

Electronic Theses and Dissertations, 2020-2023

This dissertation explores a new method for creating holographic phase masks (HPMs), which are phase transforming optical elements holographically recorded in photosensitive glass. This novel hologram recording method allows for the fast production of HPMs of any complexity, as opposed to the traditional multistep process, which includes the design and fabrication of a master phase mask operating in the UV region before the holographic recording step. We holographically recorded transmissive HPMs that are physically robust (they are recorded in a silicate glass volume), can handle tens of kilowatts of continuous wave (CW) laser power, are un-erasable, user defined, require no …

Graph Neural Networks For Improved Interpretability And Efficiency, Patrick Pho

Electronic Theses and Dissertations, 2020-2023

Attributed graph is a powerful tool to model real-life systems which exist in many domains such as social science, biology, e-commerce, etc. The behaviors of those systems are mostly defined by or dependent on their corresponding network structures. Graph analysis has become an important line of research due to the rapid integration of such systems into every aspect of human life and the profound impact they have on human behaviors. Graph structured data contains a rich amount of information from the network connectivity and the supplementary input features of nodes. Machine learning algorithms or traditional network science tools have limitation …

Balancing User Experience For Mobile One-To-One Interpersonal Telepresence, Kevin Pfeil

Electronic Theses and Dissertations, 2020-2023

The COVID-19 virus disrupted all aspects of our daily lives, and though the world is finally returning to normalcy, the pandemic has shown us how ill-prepared we are to support social interactions when expected to remain socially distant. Family members missed major life events of their loved ones; face-to-face interactions were replaced with video chat; and the technologies used to facilitate interim social interactions caused an increase in depression, stress, and burn-out. It is clear that we need better solutions to address these issues, and one avenue showing promise is that of Interpersonal Telepresence. Interpersonal Telepresence is an interaction paradigm …

Development Of An Hipsc-Cortical Neuron Long-Term Potentiation Model And Its Application To Alzheimer's Disease Modeling And Drug Evaluation, Kaveena Autar

Electronic Theses and Dissertations, 2020-2023

Alzheimer's disease (AD) is commonly characterized by a loss of cognitive function due to the deterioration of neuronal synapses from the presence of senile amyloid beta-42 (Aß42) plaques. Evaluating cognitive deficits caused by Aß42 using human cortical neurons poses a challenge due to sourcing difficulties, and the use of animal models to assess drug efficacy creates biological hurdles from lack of species translatability. Recent advances in induced-pluripotent stem cell technology have enabled the development of mature, human-based cortical neuron models. The development of an hiPSC-cortical neuron differentiation protocol facilitates the exploration of disease onset and functional analysis from a patient-derived …

The Site Evaluation Of Quercus Alba Metabolites, Zachary Alexander Byrd

Theses and Dissertations--Plant and Soil Sciences

Quercus alba has been the prominent tree species utilized in the spirits industry for decades. Of its many qualities, the ability to impart desirable flavors on spirits combined with its natural abundance makes it the ideal choice for barrels. Creating barrels is a uniform process, but variability still exists in aged spirits even when all other parameters are controlled. In this thesis, I explore how the origin of Quercus alba influences metabolite variability.

Quercus alba is a resilient species that can grow in many climates. This is seen through Quercus alba’s vast growing range, of which barrel quality white oak …

Surface Engineering For Controlled Growth And Deposition Of Nanomaterials - Assembly And Design At The Nano-Microscale, David Fox

Electronic Theses and Dissertations, 2020-2023

Materials with nanoscale dimensions offer several important benefits over bulk materials (e.g. increased surface area, low-cost, deviation from bulk properties, etc.). Such materials are critical components for next-generation energy storage materials, optoelectronic devices, and catalyst systems. However, these materials are often processed in liquid media, and their diminutive structures are fragile in the presence of capillary forces. As such, preparing uniform and stable nanomaterial coatings is a significant challenge. Herein, we discuss an approach where the substrate itself is factored into the assembly and growth of these materials. First, nanoporous surfaces were utilized to achieve a uniform deposition of one-dimensional …

Change Point Detection For Streaming Data Using Support Vector Methods, Charles Harrison

Electronic Theses and Dissertations, 2020-2023

Sequential multiple change point detection concerns the identification of multiple points in time where the systematic behavior of a statistical process changes. A special case of this problem, called online anomaly detection, occurs when the goal is to detect the first change and then signal an alert to an analyst for further investigation. This dissertation concerns the use of methods based on kernel functions and support vectors to detect changes. A variety of support vector-based methods are considered, but the primary focus concerns Least Squares Support Vector Data Description (LS-SVDD). LS-SVDD constructs a hypersphere in a kernel space to bound …

Genomic Analysis Of Pollen Grains For Forensic Applications, Luz Kelley

Electronic Theses and Dissertations, 2020-2023

With over 300,000 plant species on the planet and more than 90% of them relying on pollen for reproduction, palynology, the study of pollen grains plays a vital role in many research fields. One of them is forensic palynology, which uses pollen as a proxy to link individuals or objects to a location or instance. It relies on the fact that (1) pollen is an ever-present feature of the environment; (2) different locations have different pollen signatures, allowing for inference related to spatial tracking; (3) plants bloom at different times, allowing for temporal inference; and (4) pollen is exceptionally durable …

Translations To Support Loop Invariant Generation In Jml, Kohei Koja

Electronic Theses and Dissertations, 2020-2023

Software is used in many critical systems in the real world such as autonomous cars and medical devices. Such software must be reliable to protect the general public. One standard way to make reliable software is to use Hoare-style verification techniques. However, for Hoare-style verification of loop correctness, loop invariants are necessary but are difficult for people to write themselves. Since Java is one of the most popular programming languages in the world, it is useful to have a tool to generate loop invariants for Java programs. OpenJML is a widely used program verification tool for Java. However, it does …

Distance Perception Through Head-Mounted Displays, Sina Masnadi

Electronic Theses and Dissertations, 2020-2023

It has been shown in numerous research studies that people tend to underestimate distances while wearing head-mounted displays (HMDs). We investigated various possible factors affecting the perception of distance is HMDs through multiple studies. Many contributing factors has been identified by researchers in the past decades, however, further investigation is required to provide a better understanding of this problem. In order to find a baseline for distance underestimation, we performed a study to compare the distance perception in real world versus a fake headset versus a see-through HMD. Users underestimated distances while wearing the fake headset or the see-through HMD. …

Effficient Graph-Based Computation And Analytics, Bingbing Rao

Electronic Theses and Dissertations, 2020-2023

With data explosion in many domains, such as social media, big code repository, Internet of Things (IoT), and inertial sensors, only 32% of data available to academic and industry is put to work, and the remaining 68% goes unleveraged. Moreover, people are facing an increasing number of obstacles concerning complex analytics on the sheer size of data, which include 1) how to perform dynamic graph analytics in a parallel and robust manner within a reasonable time? 2) How to conduct performance optimizations on a property graph representing and consisting of the semantics of code, data, and runtime systems for big …