Digital Commons Network^™

Energy Based Diagnostics Of Cfd: Revealing New Insights To Complex Aerodynamics, George Loubimov

Electronic Theses and Dissertations, 2020-2023

This thesis documents a new approach to assess the aerodynamics of complex fluid dynamic systems using modern assessment methods associated with computational fluid dynamics (CFD). The method is developed to extract novel and additional insight in the context of a higher-fidelity modeling tool. Although the methods are based on classical control volume techniques balancing fluid momentum and energy, the approach uses the detailed data provided by CFD to expand on it. Classical methods typically use a fixing control volume defined at simple control surfaces, whereas this assessment method utilizes CFD to provide complex integrals on the control surfaces and uses …

Mixed-Criticality System Design For Real-Time Scheduling And Routing Upon Platforms With Uncertainties, Sudharsan Vaidhun Bhaskar

Electronic Theses and Dissertations, 2020-2023

Unlike typical computing systems, applications in real-time systems require strict timing guarantees. In the pursuit of providing guarantees, the complex dynamic behaviors of these systems are simplified using models to keep the analysis tractable. In order to guarantee safety, such models often involve pessimistic assumptions. While the amount of pessimism was reasonable for simple computing platforms, for modern platforms the pessimism involves ignoring features that improve performance such as cache usage, instruction pipelines, and more. In this work, we explore routing and scheduling problems in real-time systems, where the uncertainties in the operation are carefully accounted for by complex models …

Reconfigurable Load-Modulated Power Amplifier For Energy- And Spectrum-Efficient Wireless Communications, Haifeng Lyu

Electronic Theses and Dissertations, 2020-2023

With the increasing demand for faster date rates and extensive user connectivities, the complex modulation schemes and large-scaled arrays have been widely researched and employed in the modern wireless links e.g., 5G and beyond-5G systems. These pose major challenges to design the power amplifiers (PAs) to accommodate the system level evolution. As the critical part, the power amplifiers (PAs) dominate the output power, efficiency, linearity and reliability of the radio frequency (RF) transmitter. Consequently, the PA's capability of maintaining an efficient, linear and reliable signal amplification operation is essential to the communication systems. On the other hand, due to the …

Power Inductors: Design, Modeling And Analysis, Subash Pokharel

Electronic Theses and Dissertations, 2020-2023

Power inductors, or reactors as they are called in the power industry, are one of the fundamental components of a power system. They serve various purposes in both conventional and emerging power systems including: power flow control, fault current limitation, reactive power compensation, harmonic filtering, and others. This dissertation explores the design and applications of conventional power inductors and ways to overcome their shortcomings and expand their functionalities. In addition, novel inductor designs are proposed and analyzed to address power system challenges. A series of inductors, including traditional constant reactance inductor, gapless ferromagnetic core reactor (GFCR) (both costant and variable …

Reduced Footprint Probabilistic Inference Networks Using Novel Hybrid She-Mtj/Cmos Based Majority Gate, Harshavardhan Reddy Thummala

Electronic Theses and Dissertations, 2020-2023

In recent years, innovations in machine learning using artificial neural networks (ANN) have significantly increased and led to various applications like image recognition, text classification, machine translation, sequence recognition, etc. Earlier, research was focused on software-based DBNs, which are implemented on conventional von-Neumann architectures that provided flexibility but had few limitations. Recent studies have implemented hardware-based designs like FPGA-based, CMOS based, RRAM-based, and MRAM-based designs to overcome these limitations. Hybrid CMOS-MTJ-based RBMs provided significant area and energy improvements compared to other techniques. We herein implemented Spatial and Temporal redundant probabilistic interpolation network to improve the accuracy and provide fault tolerance …

Grid-Interactive Buildings: Modeling, Operations, And Security, Guanyu Tian

Electronic Theses and Dissertations, 2020-2023

Smart grids and smart buildings are two highly interdependent energy infrastructure systems. Buildings rely on the grid to provide reliable power while their flexibility can also be utilized to enhance the reliability and efficiency of power system operations. The quantification of heating, ventilation, and air condition (HVAC) system flexibility is critical to the operations of both the grid and buildings in demand response (DR) programs. However, the flexibility quantification is challenging due to the non-linearity and non-convexity of thermal dynamics associated with HVAC components. This dissertation proposes a novel HVAC flexibility quantification method based on a semidefinite programming (SDP) formulation. …

Leveraging Human-Centered Insights And Vision Transformers To Understand And Detect Online Risks In Teens' Private Social Media Conversations On Instagram, Joshua Gracie

Electronic Theses and Dissertations, 2020-2023

With the growing ubiquity of the internet and internet enabled devices, the issue of online risk and the need for safety measures against such risks has grown paramount. Many researchers have analyzed the scope and characteristics of online risk, especially with respect to demographics, yet few have studied the risky media itself. This work sets out to move the conversation from surveys and interviews to content analysis and automation through a comprehensive thematic analysis of online multi-media risks (images and videos) sent to and from teens in private messages on Instagram. These messages, along with demographic information such as age …

Multivariate Cognitive Walkthrough Of Qubitvr: An Educational Quantum Computing, Virtual Reality Application, Pauline Johnson

Electronic Theses and Dissertations, 2020-2023

Quantum computing is a promising field but understanding how it works can be challenging for a beginner. There are also not many educational resources to visualize and learn about quantum computing. To advance knowledge in this area, we have created QubitVR, which employs a Bloch sphere representation of a qubit, and supports trajectory visualizations and state equations in a virtual reality (VR) setting. We also conducted a multivariate cognitive walkthrough with subject matter experts (SMEs) on QubitVR to assess the effectiveness of trajectory visualizations and state equations in learning about quantum gates. The results were that trajectory visualizations aided users …

Quantum Graph Parameters, Parisa Darbari Kozekanan

Electronic Theses and Dissertations, 2020-2023

This dissertation considers some of the advantages, and limits, of applying quantum computing to solve two important graph problems. The first is estimating a graph's quantum chromatic number. The quantum chromatic number is the minimum number of colors necessary in a two-player game where the players cannot communicate but share an entangled state and must convince a referee with probability one that they have a proper vertex coloring. We establish several spectral lower bounds for the quantum chromatic number. These lower bounds extend the well-known Hoffman lower bound for the classical chromatic number. The second is the Pattern Matching on …

Methods For Defending Neural Networks Against Adversarial Attacks, Sharvil Shah

Electronic Theses and Dissertations, 2020-2023

Convolutional Neural Networks (CNNs) have been at the frontier of the revolution within the field of computer vision. Since the advent of AlexNet in 2012, neural networks with CNN architectures have surpassed human-level capabilities for many cognitive tasks. As the neural networks are integrated in many safety critical applications such as autonomous vehicles, it is critical that they are robust and resilient to errors. Unfortunately, it has recently been observed that deep neural network models are susceptible to adversarial perturbations which are imperceptible to human vision. In this thesis, we propose a solution to defend neural networks against white box …

Algorithms For The Detection Of Resolved And Unresolved Targets In The Infrared Bands, Bruce Mcintosh

Electronic Theses and Dissertations, 2020-2023

This dissertation proposes algorithms for the detection of both resolved and unresolved targets in the infrared bands. Recent breakthroughs in deep learning have spurred major advancements in computer vision, but most of the attention and progress has been focused on RGB imagery from the visual band. The infrared bands such as Long Wave Infrared (LWIR), Medium Wave Infrared (MWIR), Short Wave Infrared (SWIR) and Near Infrared (NIR) each respond differently to physical phenomena, providing information that can be used to better understand the environment. The first task addressed is that of detecting vehicles in heavy clutter in MWIR imagery. A …

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, …

Visual Question Answering: Exploring Trade-Offs Between Task Accuracy And Explainability, Aisha Urooj

Electronic Theses and Dissertations, 2020-2023

Given visual input and a natural language question about it, the visual question answering (VQA) task is to answer the question correctly. To improve a system's reliability and trustworthiness, it is imperative that it links the text (question and answer) to specific visual regions. This dissertation first explores the VQA task in a multi-modal setting where questions are based on video as well as subtitles. An algorithm is introduced to process each modality and their features are fused to solve the task. Additionally, to understand the model's emphasis on visual data, this study collects a diagnostic set of questions which …

Computational Methods To Analyze Next-Generation Sequencing Data In Genomics And Metagenomics, Saidi Wang

Electronic Theses and Dissertations, 2020-2023

This thesis focuses on two important computational problems in genomics and metagenomics with the public available next-generation sequencing data. One is about gene regulation, for which we explore how distal regulatory elements may interact with the proximal regulatory elements. The other is about metagenomics, in which we study how to reconstruct bacterial strain genomes from shotgun reads. Studying gene regulation, especially distal gene regulation, is important because regulatory elements, including those in distal regulatory regions, orchestrate when, where and how much a gene is activated under every experimental condition. Their dysfunction results in various types of diseases. Moreover, the current …

Characteristics Of Rotating Detonation Engines For Propulsion And Power Generation, Robert Burke

Electronic Theses and Dissertations, 2020-2023

Conventional engines are limited by the efficiency of their combustion mode. Compared to present constant pressure deflagration-based engines, detonation-based systems can realize a higher thermodynamic cycle efficiency, making them an attractive candidate for next generation propulsion systems that will take humanity to hypersonic speeds and even to Mars. For all its performance gains, detonation engines are still far off from implementation. One system, the rotating detonation engine (RDE) is promising as a detonation-based engine concept for its stability, simplicity, and versatility. For these reasons, RDEs have been the subject of studies internationally in efforts to understand their operation and integration …

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 …

An Investigation Of The Relationship Between Respiration And Seismocardiographic Signals Using Signal Processing, Machine Learning And Finite Element Analysis, Tanvir Hassan

Electronic Theses and Dissertations, 2020-2023

Cardiovascular disease (CVD) is one of the major causes of death worldwide. Disease management, as well as patient health, can be significantly improved by early detection of patient deterioration and proper intervention. Review of the patient's medical history and physical examination including stethoscope auscultation and electrocardiograms (ECG), echocardiography imaging, numerous blood testing, and computed tomography are common means of evaluating cardiac function. Seismocardiographic (SCG) signals are the vibrations of the chest wall due to the mechanical activity of the heart. These signals can provide useful information about heart function and could be used to diagnose cardiac problems. The variability in …

Examining Cooperative System Responses Against Grid Integrity Attacks, Alexander D. Parady

Honors Undergraduate Theses

Smart grid technologies are integral to society’s transition to sustainable energy sources, but they do not come without a cost. As the energy sector shifts away from a century’s reliance on fossil fuels and centralized generation, technology that actively monitors and controls every aspect of the power infrastructure has been widely adopted, resulting in a plethora of new vulnerabilities that have already wreaked havoc on critical infrastructure. Integrity attacks that feedback false data through industrial control systems, which result in possible catastrophic overcorrections and ensuing failures, have plagued grid infrastructure over the past several years. This threat is now at …

Learning And Decision Making In Social Media Networks, Zhecheng Qiang

Electronic Theses and Dissertations, 2020-2023

Social media is a virtual community where users share news, ideas, interests, and information. Learning the information diffusion dynamics and making decisions correspondingly, e.g., selecting the seed nodes to maximize the influence, have been widely applied to the areas of viral marketing and cyber security. In this dissertation, we study the problem of learning diffusion process, i.e., infection prediction, in social media networks utilizing both feature-based machine learning methods and mathematical model-based methods. For feature-based machine learning methods, the neighborhood information is treated as an important feature together with user profile and content similarity features. For model-based methods, two distinctive …

Decoding Task-Based Fmri Data Using Graph Neural Networks, Considering Individual Differences, Maham Saeidi

Electronic Theses and Dissertations, 2020-2023

Functional magnetic resonance imaging (fMRI) is a non-invasive technology that provides high spatial resolution in determining the human brain's responses and measures regional brain activity through metabolic changes in blood oxygen consumption associated with neural activity. Task fMRI provides an opportunity to analyze the working mechanisms of the human brain during specific task performance. Over the past several years, a variety of computational methods have been proposed to decode task fMRI data that can identify brain regions associated with different task stimulations. Despite the advances made by these methods, several limitations exist due to graph representations and graph embeddings transferred …

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. …

How Adolescents In The Child Welfare System Seek Support For Their Sexual Risk Experiences Online, Taylor L. Moraguez

Honors Undergraduate Theses

Youth in the foster care system experience unique and challenging situations online, such as higher risks of inappropriate messaging (e.g., sexting) and unwanted solicitations from strangers. As a vulnerable group of adolescents, foster youth often use online platforms as a resource to express themselves and seek support over their sexual experiences online. This thesis analyzes how foster youth seek support online for their sexual risk experiences, including sexual abuse, sexting, and sexuality. To understand how adolescents (ages 13-17) in the child welfare system seek support for these experiences, we conducted a thematic analysis of 541 individual posts made by 121 …

Thermofluidic Characterization Of Carbon Dioxide Near Critical Conditions At Microscale, Anatoly Parahovnik

Electronic Theses and Dissertations, 2020-2023

This work revealed the thermo physical characteristics of near critical and supercritical carbon dioxide at the micro scale. The results include the extension of flow boiling heat transfer correlations, boiling inception, near critical bubble dynamics, thermalization mode shift, Joule Thomson effect and pressure drop evaluation. It was found that extremely low superheat temperatures are required for boiling inception near the critical conditions (i.e., T=31.4 °C, and P=7.37 MPa), and boiling heat transfer correlations were extended up to a reduced pressure of 0.99. The work also revealed a significant enhancement of the heat transfer coefficient as the critical conditions approached, which …

Data-Driven Modeling Of Mechanical Behaviors Of Additively Manufactured Materials, Ziyang Zhang

Electronic Theses and Dissertations, 2020-2023

Additive manufacturing (AM) is a revolutionary technology that greatly improves the flexibility of fabricating parts with complex structures and eliminates the cost of making molds. While AM techniques offer unique benefits over traditional manufacturing processes, it is challenging to predict the mechanical behaviors of additively manufactured parts based on design and process parameters. With recent advances in machine learning, data-driven methods have the potential to overcome such limitations. In this work, data-driven modeling frameworks were proposed to predict the tensile, flexural, and compressive behaviors of additively manufactured plastics and composites. Ensemble learning was used to predict the tensile strength of …

Vibrations Of Rotationally Periodic Structures: A Metric For Mistuning Characterization And Vibration Localization, Andres Rodriguez

Electronic Theses and Dissertations, 2020-2023

Blisk components are an integral part of jet engines and power generation systems. Composed of a single monolithic structure, integral blisks combine the blade-and-disk portion of primary components such as the fan, compressor stage, or turbine stage. This design modification increases the aerodynamic performance while decreasing the cost and eliminating time of assembly. However, these benefits come with the loss of blade-disk connection interfaces, which greatly reduces the structure's damping and its ability to attenuate unwanted structural vibrations. Blisk dynamics are impacted by mistuning, which is a disruption of the periodic symmetry of otherwise identical bladed sections. This disruption degrades …

Complex Quantum Contagion: A Quantum-Like Approach For The Analysis Of Co-Evolutionary Dynamics Of Social Contagion, Ece Mutlu

Electronic Theses and Dissertations, 2020-2023

Modeling the dynamics of social contagion processes has recently attracted a substantial amount of interest from researchers due to its wide applicability in network science, multi-agent systems, information science, and marketing. Unlike in biological spreading, the existence of a reinforcement effect in social contagion necessitates considering the complexity of individuals in the systems. Although many studies acknowledged the heterogeneity of the individuals in their adoption of information (or behavior), there are no studies that take into account the individuals' uncertainty during their decision-making despite its theoretical and experimental evidence in behavioral economics, decision science, cognitive science, or multi-agent systems. This …

An Experimental Investigation Of Creativity In Relation To Extracurricular Activity And Gpa In Undergraduate Engineering Students, Maria Gonzalez

Electronic Theses and Dissertations, 2020-2023

Measuring creativity for engineering is paramount; previous research has shown that creativity diminishes as students advance through college. This study intends to find possible predictors for creativity in these students. These predictors include GPA, Hobbies, and Extracurriculars while using the Test of Creativity Thinking – Drawing Production (TCT-DP) as a benchmark for creativity. Participants were Junior and Senior year engineering students in Spring 2021. All eligible study participants were provided a TCT-DP and survey to complete. Individual creative ability was assessed from the resulting TCT-DP using a 13 categorical scoring matrix by independently trained evaluators using the scoring guidelines. The …

Generic Behavior Framework Of Sx And Ds Nickel-Base Superalloys With Applications To Constitutive And Life Prediction Modeling, Firat Irmak

Electronic Theses and Dissertations, 2020-2023

Selection of materials to be used for components experiencing extreme conditions is a critical process in the design phase. Nickel-base superalloys have been frequently used for hot gas path components in the turbomachinery industry. These components are required to withstand both fatigue and creep at extreme temperatures during their service time. In general, the extreme temperature materials mostly embody polycrystalline, directionally solidified, and single crystal superalloys. It is essential for design engineers to predict accurate damage behavior and lifespan for these components to prevent catastrophic failures. This dissertation presents a new framework to represent mechanical behavior of Nickel-base superalloys under …

The Effects Of Viscous Damping On Rogue Wave Formation And Permanent Downshift In The Nonlinear Schrödinger Equation, Evelyn Smith

Honors Undergraduate Theses

This thesis investigates the effect of viscous damping on rogue wave formation and permanent downshift using the higher-order nonlinear Schrödinger equation (HONLS). The strength of viscous damping is varied and compared to experiments with only linear damped HONLS.

Stability analysis of the linear damped HONLS equation shows that instability stabilizes over time. This analysis also provides an instability criterion in the case of HONLS with viscous damping.

Numerical experiments are conducted in the two unstable mode regime using perturbations of the Stokes wave as initial data. With only linear damping permanent downshift is not observed and rogue wave formation is …

A Fall From Grace: The Rising Rate Of Attorneys With Substance Abuse Disorders, Chemical Dependencies And Addictions, Amy M. Yost

Honors Undergraduate Theses

This thesis is a continuation of research and scholarly writing that the author completed for a published article that appeared in Volume 5 of the University of Central Florida Undergraduate Law Journal, Spring 2022. The rising rate of attorneys with a self-reported substance abuse disorder, chemical or alcohol dependency, as the data reveals, is the highest in our country’s history. Although the notion of attorney addictions and dependency issues may come as a surprise to those outside of the legal community, these issues are not breaking news. Rather, the data has been slowly emerging due to the increasing number of …