Physical Sciences and Mathematics Commons^™

Koopman-Inspired Proximal Policy Optimization (Kippo), Andrei Cozma

Masters Theses

Reinforcement Learning (RL) has made significant strides in various domains, yet developing effective control policies for environments with complex, nonlinear dynamics remains a challenge, particularly for policy gradient methods. These methods often struggle due to high-variance in gradient estimates, non-convex optimization landscapes, and sample inefficiency, resulting in unstable learning, suboptimal policies, and trade-offs between performance and reproducibility. The quest for more robust, stable, and effective methods has led to numerous innovations and remains a critical area of research. Proximal Policy Optimization (PPO) has gained popularity in recent years due to its balance in performance, training stability, and computational efficiency. In …

Comparison Of Core-Collapse Supernova Explosions With 15 Solar Mass Progenitors, Chien-Hui Chen

Masters Theses

The study of core-collapse supernovae (CCSNe) helps us understand the origin and history of chemical abundances in our Universe. Previous numerical studies of CCSNe have shown the importance of non-radial motion in pre-collapse progenitors on the explosion outcome. In this thesis, I use the 2D Chimera neutrino radiation hydrodynamics code to run simulations of four models with 15 solar mass (M⊙) progenitors but different initial conditions sourced from different 1D and 2D pre-collapse burning environments. To analyze the models, I compare the explosion evolution of their nuclear abundances, shocks, neutrino heating, accretion, explosion geometry, and turbulent convection. Despite the differences …

Advancing Thermal Property Measurements And Water Management For Controlled Environment Agriculture On Earth And Beyond, Chihiro Dixon

All Graduate Theses and Dissertations, Fall 2023 to Present

Space exploration stands as one of humanity's most profound endeavors, and plant growth in space is essential for sustaining astronauts during long-duration missions. However, operating plant growth systems under reduced gravity conditions presents challenges, particularly in ensuring uniform water distribution in the root zone. Non-uniform water distribution such as excess water and/or insufficient water in the root zone can significantly impact plant yield, necessitating the need to accurately estimate water status in the root zone and understand the dynamics of water flow in plant growth media under reduced gravity conditions. The objectives of this research were to enhance the accuracy …

Analyzing Hubble Space Telescope Images Of Agn Host Galaxies With Keck Integral Field Spectra, Sebastian Contreras

Physics

In the center of most massive galaxies is a supermassive black hole (SMBH) with a mass that can range from millions to billions of solar masses. It has been observed that more massive SMBHs have a more massive host galaxy bulge, as evidenced by the larger bulge luminosity and stellar velocity dispersion, a correlation known as the BH mass - host-galaxy scaling relation. It suggests a close evolutionary connection between the growth of the SMBH and the growth of its host galaxy. If a SMBH develops an accretion disk to fuel an active galactic nucleus (AGN), it will emit radiation …

Fishing Vessel Detection In Exclusive Economic Zones From Low Earth Orbit Satellites With Power And Computational Constraints, Kyler E. Nelson

All Graduate Theses and Dissertations, Fall 2023 to Present

Illegal fishing activities pose a significant threat to the sustainability of marine ecosystems and the economies and societies which rely on them. Detection of fishing vessels engaging in illegal activity is difficult, as many ships engaging in such activity actively avoid detection through radio systems used for maritime traffic monitoring. Satellite imagery provides a promising means for detecting fishing vessels, though designing an effective system is difficult due to limited availability of labeled image datasets of fishing vessels. This research proposes a system to detect illegal fishing activity through the use of a low-power ship detection satellite and proposes a …

Interactions Between Nano/Micro-Sized Particles And Microbes For Agricultural And Environmental Applications, Li-Ting Yen

All Graduate Theses and Dissertations, Fall 2023 to Present

Among the challenges posed by a growing global population, diminishing arable land and water resources affected by climate change are critical for enhancing crop yields, ensuring food security, and maintaining water quality and environmental health.

Iron (Fe), an essential micronutrient, is vital to plant growth. The partially oxidized form of vivianite, metavivianite (metaVT), is reported to be a promising alternative Fe fertilizer. Previous studies have shown the effectiveness of bulk metaVT on plants grown on calcareous soil for mitigating Fe efficiency and the extremely low solubility of bulk metaVT (Ksp=10^-36) in electrolyte solutions, such as CaCl₂. …

Novel Quantum Algorithms For Noisy Intermediate-Scale Quantum (Nisq) Devices, Shikha Bangar

Doctoral Dissertations

Quantum computers hold the immense potential to revolutionize the current computing technology. However, the available quantum hardware, known as noisy intermediate-scale quantum (NISQ) devices, poses a challenge as these devices have noise and imperfect qubits. Hence, there is a critical need to develop novel algorithms specifically designed to harness the capabilities of these devices. This work aims to develop and optimize such quantum algorithms for implementation on current quantum technologies by integrating principles from physics and machine learning. First, we developed the Quantum Imaginary Time Evolution (QITE) and Quantum Lanczos (QLanczos) algorithms on discrete-variable quantum computing settings to study the …

Quantinar: A Blockchain Peer-To-Peer Ecosystem For Modern Data Analytics, Raul Bag, Bruno Spilak, Julian Winkel, Wolfgang Karl Hardle

Sim Kee Boon Institute for Financial Economics

The power of data and correct statistical analysis has never been more prevalent. Academics and practitioners require nowadays an accurate application of quantitative methods. Yet many branches are subject to a crisis of integrity, which is shown in an improper use of statistical models, p-hacking, HARKing, or failure to replicate results. We propose the use of a Peer-to-Peer (P2P) ecosystem based on a blockchain network, Quantinar, to support quantitative analytics knowledge paired with code in the form of Quantlets or software snippets. The integration of blockchain technology allows Quantinar to ensure fully transparent and reproducible scientific research.

Quantum Computing And Information For Nuclear Physics, Chenyi Gu

Doctoral Dissertations

Quantum computation and quantum information, hot topics with immense potential, are making exciting strides in nuclear physics. The computational complexity of nuclear physics problems often surpasses the capabilities of classical computers, but quantum computing offers a promising solution. My research delves into the application of quantum computation and quantum information in nuclear physics.

I am curious about how to approach nuclear physics problems on a quantum computer. This dissertation studies how to prepare quantum states with quantum algorithms, as state preparation is a crucial initial step in studying nuclear dynamics. Two different quantum algorithms are studied: (i) the time-dependent method, …

Addressing Lead Exposure Disparities In Milwaukee: A Geographical Analysis Of Interventions And Equitable Strategies, Miracle Mark

Theses and Dissertations

Lead exposure is still a major public health issue, especially for children who are the most vulnerable due to the negative effects on their development. Inner-city neighborhoods are often disproportionately impacted because they tend to have older housing stock, which includes sources of lead such as lead paint and lead service lines. While many studies have examined different types of lead interventions in the U.S., including both primary and secondary interventions, little is known about the lead intervention landscape in the city of Milwaukee. Specifically, it is unclear whether the geography of intervention matches up with the geography of exposure. …

Astrophysics, Cosmology, And Fundamental Interactions With Gravitational Waves, Anarya Ray

Theses and Dissertations

Several unresolved mysteries remain in our understanding of the universe that can be elucidated with a growing catalog of gravitational wave~(GW) and multi-messenger observations of compact binary coalescences~(CBCs). Current and future catalogs, assisted by robust modeling and scalable inference frameworks, will lead to new insights into the poorly understood physics of compact binary formation, independent measurements of the cosmological expansion, and unprecedented empirical probes into the very nature of fundamental interactions. The scientific potential of GW observations from CBCs is significantly enhanced through the detection of their multi-messenger counterparts. Similarly, multi-probe explorations of compact object universal properties that combine GW …

Solving Large Job Shop Scheduling Problems: Using Graph Classification Via Graph Neural Networks To Pre-Seed A Genetic Algorithm For Machine Dispatching Rule Optimization, Isaac Schwab

Theses and Dissertations

The job shop scheduling problem is a difficult problem to solve, and it is also difficult to implement solutions found in research into real shops. In this research, a methodology is proposed to develop schedules for real shops. The methodology utilizes a genetic algorithm to select dispatching rules for each machine cell and accesses these schedules through a simulation optimization framework. The simulation framework allows for the study of random elements including variable job processing times and random machine breakdowns. This creates a robust schedule that is easy to understand, and therefore implement, while scaling to large, real-world job shops. …

Using Polonium-210 To Estimate Particulate Organic Carbon Consumption By Dreissenid Mussels In Lake Michigan, Rachel Ann Smith

Theses and Dissertations

In this study, I examine the potential of using the naturally occurring radionuclide Polonium-210 (half-life = 138.376 days) to estimate the in situ consumption of particulate organic carbon (POC) by dreissenid mussels in Lake Michigan. To estimate POC uptake, I measured the ratio of POC to particle-bound 210Po in the water column above the lakebed, as well as the inventory of 210Po being stored in mussel tissue on the lakebed at three sites with depths of 40, 50 and 80 meters. Additionally, I conducted lab incubation experiments to determine the biological half-life of 210Po in mussel tissue. These measurements were …

Using Lead-210, Bismuth-210, And Polonium-210 To Estimate Particulate Organic Carbon Flux To The Benthos Of Lake Michigan, Gage Justman Hunter

Theses and Dissertations

210Bi is a short-lived (t1/2: 5.01 days) naturally occurring radionuclide and a potential tracer of particle dynamics in high flux aquatic environments such as lakes, coastal oceans, and continental shelves. While its parent, 210Pb, and daughter, 210Po, have been used to estimate particle removal rates from the ocean, few studies have investigated the behavior of 210Bi in aquatic systems or its use as a tracer of particle export fluxes. In this study, a time series experiment was conducted where 210Pb, 210Bi, and 210Po activities were measured in rainwater and in the water column on the slope of southwestern Lake Michigan. …

Use Of Geomagnetic Paleointensity As A Correlation Tool In The Eastern Snake River Plain Lava Flows, Melissa Marie Sikes

Theses and Dissertations

The Snake River Plain volcanic province stretches 600 km from eastern Oregon across southern Idaho and into northwest Wyoming. Over the past ~14 million years, olivine tholeiitic lava flows have accumulated. To assess ongoing volcanic hazards, it is important to quantify the number, timing, and size of eruptive events. This assessment requires correlating lava flows across coreholes within the Eastern Snake River Plain. Previous paleomagnetic research applied paleomagnetic inclinations to correlate flows between coreholes. This study tests whether using geomagnetic paleointensity – in addition to inclination – can increase confidence in the correlation of these flows. Pilot samples were retrieved …

Contraction Rates For Mckean-Vlassov Stochastic Differential Equations, Dan Noelck

Theses and Dissertations

In response to the pressing need of modeling, analyzing and applying complex systems with inherent distribution- and memory-dependent dynamical behaviours, this dissertation investigates both distribution- and memory-dependent stochastic differential equations. Following the establishment of the well-posedness of these stochastic differential equations, this dissertation is focused on asymptotic properties of the underlying processes. Under suitable conditions on the coefficients of the stochastic differential equations, this dissertation derives explicit quantitative contraction rates for the convergence in Wasserstein distance for McKean-Vlasov stochastic differential equations (MVSDEs) and McKean-Vlasov functional stochastic differential equations (MVFSDEs). The obtained contraction results for MVSDEs are further utilized to demonstrate …

Evaluation Of Factors Impacting Predictor Importance Results In Multilevel Models, Soonhwa (Suna) Paek

Theses and Dissertations

Background: Dominance Analysis (DA) was originally proposed to determine the relative importance of predictor variables in OLS regression models by comparing the change in model fit (i.e., R2) resulting from adding each predictor to each possible subset model (Azen & Budescu, 2003; Azen, 2013; Budescu, 1993). Although various educational studies show that DA can provide useful information in research, the DA procedure has not been studied extensively with Multilevel Linear Models (MLMs), which are commonly used to analyze nested data structures.

Purpose: This study aimed to identify appropriate multilevel measures of fit for the DA procedure in various MLMs, and …

Cte Induced Premium Principles And Properties, Linjiao Wu

Theses and Dissertations

The traditional pricing approach in the insurance industry assumes independence among insureds, yet overlooks the complexities of interdependent risk profiles. This dissertation addresses this limitation by proposing a premium pricing model tailored for managing dependent risks, drawing inspiration from conditional tail expectation (CTE) theory. In our model, each individual insured's premium is contingent upon the collective loss surpassing a predefined threshold.

To validate the efficacy of our model, we introduce several key properties to ensure fairness and stability in premium determination among insured individuals, including diversification and monotonicity. Diversification ensures that adding one policyholder to the insured group does not …

Paleoenvironmental Constraints On Pleistocene Ice Sheets From Glacio-Volcanic Deposits In Northeast Iceland, Cameron Essex

Theses and Dissertations

There are indications that the melt-back of glaciers due to climate change can trigger new eruptions for volcanoes and magma reservoirs that rest under ice sheets. The ideal locality on Earth to study volcano-ice interactions is Iceland, an active volcanic island that has been totally covered in previous ice ages. Eruptions under glaciers produce distinctive landforms called tuyas, or table mountains, which can provide an estimate of ice thickness at the time of eruption. One research tool used to investigate ice thickness is volcanic glass, which is formed from rapid cooling of magma, and thus is abundant in the majority …

Urban Rail-Trails As Spaces Of Distributive, Procedural, And Recognitional (In)Justice, Katherine Kocisky

Theses and Dissertations

This dissertation research draws attention to urban rail-trail projects as issues of social (in)justice. Like urban greenspace, rail-trails are not an unproblematic environmental good. Large, high-profile urban rail-trails like New York City’s High Line, Chicago’s 606 Bloomingdale Trail and Atlanta’s Beltline have all received criticism for accelerating gentrification in surrounding communities, most often displacing historically excluded communities adjacent to the trail. Less research has explored relationships between urban rail-trail development and cultural displacement. This research aims to fill that gap by understanding how contemporary urban rail-trail projects are incorporating equity into their planning processes and whether urban rail-trails can be …

Spectral Characterization Of Volcanic Materials On Earth And Venus, C.J. Leight

Doctoral Dissertations

Earth and Venus are dominated by volcanic landforms, making accurate characterization of the diversity of igneous compositions on the planets’ surfaces key to understanding their geologic histories. Spectral observations in the visible-near-infrared (VNIR) and mid-infrared (MIR) provide rapid characterization of surface composition and mineralogy but are not without limitations. Spectra are sensitive to a number of factors, including observation geometry, collection method (emissivity or reflectance), grain size, phase assemblage, and composition. It is impossible to constrain the various effects of all factors when interpreting orbital data, and simplifications are made, guided by laboratory investigations.

A common simplification is to ignore …

Renormalization As A Tool For Nuclear Scattering & Binding, Chinmay Mishra

Doctoral Dissertations

Chiral effective field theory is the state-of-the-art when it comes to describing low-energy nuclear phenomena in a systematically-improvable and model-independent fashion. It is grounded in quantum chromodynamics – the fundamental theory underlying nuclear interactions – and consists of pion and nucleon degrees of freedom. In this framework, nuclear interaction is mediated by pions at long distances (in comparison to length scales at which quarks and gluons can be resolved), while finite-range “contact” terms account for the physics at short-distances. Together, they are organized into a hierarchy based on the orders (in powers of small momenta over a large momentum scale) …

Investigating Liquid-Liquid Phase Separation In Lipid Bilayers: A Multi-Modal Approach Utilizing Spectroscopy, Microscopy, And Cryo-Em, Karan D. Sharma

Doctoral Dissertations

This thesis explores the characterization of liquid-liquid phase separation in model lipid bilayers using fluorescence, optical microscopy, and cryo-electron microscopy (cryo-EM) integrated with machine learning (ML) analysis. The plasma membrane has a complex composition, lateral heterogeneity and dynamic structure which makes it challenging to study. Simplified model membranes containing three or four-component lipid mixtures, typically comprising low- and high-melting lipids along with cholesterol, form phase separated systems that mimic lateral heterogeneity/lipid rafts in biomembranes. In living cells, lipid rafts are thought to form nanoscopic domains smaller than 200 nm. These domains cannot be resolved by conventional optical microscopy. For a …

Exploring The Integration Of Blockchain In Iot Use Cases: Challenges And Opportunities, Ivannah George

Electronic Theses, Projects, and Dissertations

Blockchain and The Internet of Things (IoT) is a significant paradigm which has gained traction in today’s digital age as two complimentary technologies. The combination of IoT's connectivity with blockchain's security creates new opportunities and solves problems associated with centralized systems. This culminating project aims to delve deeper into the integration of blockchain technology in IoT applications based on select use cases to uncover potential benefits and significant challenges of blockchain integration across different sectors. The research objectives to be addressed are: (RO1) How emerging vulnerabilities manifest in the implementation of blockchain within current IoT ecosystems. (RO2) How current opportunities …

Rapid Parameter Estimation Of Gravitational Wave Sources & Homologous Expansion In Common Envelope Events, Vinaya Valsan

Theses and Dissertations

Binary star systems are crucial for advancing our understanding of the universe. My doctoral research focuses on two related topics within the domain of binary star dynamics: gravitational waves from compact binary stars, and the evolution of the common envelope in stellar mass binaries.

In the era of multi-messenger astrophysics, swift identification and characterization of gravitational wave events is important for subsequent electromagnetic observations. The development of low-latency parameter estimation techniques is essential for providing astronomers with crucial information regarding the potential electromagnetic counterparts to gravitational wave signals. RapidPE is a highly parallelized parameter estimation scheme that achieves low-latency parameter …

Robust-Efficient Fitting Of Loss Models Via Quantile Least Squares, Mohammed Adjei Adjieteh

Theses and Dissertations

Actuaries and statisticians use statistical models to predict future losses for pricing and other purposes. However, a key challenge in modeling is estimating the unknown parameters that index these distributions. Ensuring both efficiency and robustness of the chosen method is crucial, especially given the prevalence of outliers or extreme losses in insurance claims data. The primary objective of this dissertation is to introduce a robust, efficient, and computationally easy parameter estimation method that can be applied to various loss modeling scenarios. The proposed method exploits the joint asymptotic normality of sample quantiles (of i.i.d. random variables) to construct both ordinary …

Novel Physics In Unconventional Superconductors, Adil Amin

Theses and Dissertations

In this work, we consider the interplay of different magnetic orders and superconductivity.We consider both phenomenological and microscopic models to capture these interactions. The models are built using group theoretic arguments to ensure the constraints provided by the crystal symmetry are satisfied. We first consider a phenomenological theory for two transitions in superfluid 3He which involves coupling superfluidity and spin fluctuations through an approach called spin fluctuation feedback effect. We then apply this phenomenological approach to UPt3, PrOs4Sb12 and U1−xThxBe13 to obtain a common underlying mechanism for two superconducting transitions. We then consider odd-parity multipolar antiferromagnetic order i.e. Kramers’ degenerate …

Enhancing Interactions Among Dipole Excitations Using Surface Plasmon Polaritons: Quantum Entanglement And Classical Interactions, Jay Berres

Theses and Dissertations

The interaction of light with matter at the nano-scale continues to be an important research area for the application of nano-optical devices in wide ranging areas such as biosensing, light harnessing, and optical communications, to name a few. An important aspect of this is the interaction among dipole excitations (which includes classical dipole emitters, and dipole approximations of atoms, molecules, and other quantum objects), mediated by the device medium where they are located. Since the dimensions of these devices, by design, are at the nano-scale, the size of the dipole-dipole interaction space is much less than the wavelength of light …

Mixdown Altitudes As A Method Of Forecasting Peak Wind Gusts Under High-Pressure Conditions, Danica Brezovar

Theses and Dissertations

Wind gusts are small-scale weather phenomena characterized by sudden, brief increases in wind speed (American Meteorological Society 2023), posing significant forecasting challenges due to their small spatial and temporal scales. These gusts are typically assumed to be caused by turbulent eddies circulating fast winds aloft down to the surface. Accurate forecasting of wind gusts is crucial across various sectors, including wind energy, structural engineering, and electric power distribution, where gusts can cause substantial economic impacts. Current forecasting methods either rely on the dynamical assumption that boundary layer turbulence mixes momentum down to the surface or predominantly statistical methods that typically …

High Temperature Alteration Conditions Within Lava Tubes: An Analogue For Venus Surface Geology, Dylan Alexander Childs

Theses and Dissertations

Scientific exploration of other planetary bodies comes with many limitations, and Venus is no exception. Average surface temperatures of ∼460°C and an atmospheric pressure of ∼96 bars has severely limited the longevity of any instruments sent to the surface of Venus. Furthermore, with an atmosphere composed of ∼96.5% CO2, there are only three wavelength windows in the near infrared region that can be used to measure the mineralogical composition of the surface. Due to these constraints, our understanding of Venus’ surface mineralogy is severely limited and to date direct measurements of its geologic composition are limited to a handful of …