Digital Commons Network^™

Xps Study Of Calcium Lanthanum Sulfide Ceramics, Brian E. Butkus

Graduate Thesis and Dissertation 2023-2024

Long wave infrared (LWIR) optics that transmit in the 8 to 14 m wavelength range and, additionally, can withstand severe physical and thermal stresses are needed for advanced remote sensing, guidance and communication-based applications. However, most non-oxide transparent LWIR optics do not have the wider transmission range, nor the hardness and resistance to thermal shock needed for extreme environments. Because of these limitations, research is circling back to a promising material, calcium lanthanum sulfide (CLS), that could meet LWIR needs for extreme environments.

In this thesis, we will demonstrate the abilities of x-ray photoelectron spectroscopy (XPS) as a technique for …

Physical Properties And Chemical Composition Of Comets, Olga Harrington

Electronic Theses and Dissertations, 2020-2023

Comets and Centaurs are icy remnants from the formation of the solar system. Analyzing the physical properties of their nuclei and their production rates can serve as powerful tools for tracing primitive solar system material. The four research projects in this dissertation examine these properties in comets and Centaurs. The first project focuses on observations of main belt comet 176P/LINEAR that were obtained with the Kepler space telescope. Optical lightcurves were used to constrain models of the nucleus's spin pole axis, shape and activity level. The second project used millimeter-wavelength spectra from the Arizona Radio Observatory Submillimeter Telescope and infrared …

A Systematic Review Of Cryptocurrencies Use In Cybercrimes, Kieran B D Human

Graduate Thesis and Dissertation 2023-2024

Cryptocurrencies are one of the most prominent applications of blockchain systems. While cryptocurrencies promise many features and advantages, such as decentralization, anonymity, and ease of access, those very features can be abused. For instance, as documented in various recent works, cryptocurrencies have been frequently abused in many different forms of cybercrime. Despite the plethora of works on measuring and understanding the abuse of cryptocurrencies in the digital space, there has been no work on systemizing this knowledge by comprehensively understanding those contributions, contrasting them based on their merit, and understanding the gap in this research space.

This thesis initiates the …

A Holistic Work System Approach To Creating Flow During Transactional Work, Steven Clapp

Electronic Theses and Dissertations, 2020-2023

Psychological flow is a positive mental state where one is so fully concentrated in a challenging task that self-consciousness falls away, time seems to stand still, and the reward is the experience of meeting the challenge. Previous research on flow in the workplace has been performed on how to create conditions to promote its occurrence in workers, to describe its attendant individual and organizational benefits, and to measure it through self-reported means and physiologically. Such research has been focused on creative endeavors (such as the arts, sports, medicine, teaching), where individuals have high agency over the execution of activities needed …

Instrumental Approaches For High Resolution Photoluminescence Spectroscopy And Its Applications To Environmental Analysis, Anthony Santana

Electronic Theses and Dissertations, 2020-2023

Photoluminescence phenomena provide valuable information for the direct analysis of target chemicals in complex samples. To take full advantage of the information content of fluorescence and phosphorescence phenomena, the analyst should have access to instrumentation capable to record data formats in the wavelength and time domains. Previous efforts in our lab have developed laser-based instrumentation to combine spectral and lifetime information into data formats known as wavelength time matrices (WTMs) and time-resolved excitation emission matrices (TREEMs). Recording WTMs during the emission decay of the sample makes it possible to unambiguously identify chemicals on the bases of spectral and lifetime information. …

Navigating With Sharks: How The Marketing Practices Help To Create Successful Phishing Emails, Erica Castilho

Graduate Thesis and Dissertation 2023-2024

A phishing email is a crime where a scammer sends an email to get sensitive data. Everyday phishing email attacks impact billions of people worldwide. Preparing users to better identify phishing and avoid risky engagement with it is essential to combat this threat. We consider that as phishing emails and email marketing aim to target email clicks, scammers can use marketing practices in phishing emails to achieve their goals. However, the security research community doesn't explore deeply the similarities between phishing and email marketing. This study presents a distinctive framework known as the Phishing Engagement Marketing Optimization (PEMO). The primary …

Exploring The Feasibility Of Machine Learning Techniques In Recognizing Complex Human Activities, Shengnan Hu

Graduate Thesis and Dissertation 2023-2024

This dissertation introduces several technical innovations that improve the ability of machine learning models to recognize a wide range of complex human activities. As human sensor data becomes more abundant, the need to develop algorithms for understanding and interpreting complex human actions has become increasingly important. Our research focuses on three key areas: multi-agent activity recognition, multi-person pose estimation, and multimodal fusion.

To tackle the problem of monitoring coordinated team activities from spatio-temporal traces, we introduce a new framework that incorporates field of view data to predict team performance. Our framework uses Spatial Temporal Graph Convolutional Networks (ST-GCN) and recurrent …

Surface Engineering Of Nanoparticles For Efficient Polymerization Inhibition, Catalysis, And Plasmonic Sensing, Pooria Golvari

Graduate Thesis and Dissertation 2023-2024

Surface modification of colloidal nanoparticles is essential for broadening the scope of nanotechnology. In this dissertation, we discuss novel approaches to functionalize the surface of nanoparticles to tailor their properties for applications including radical polymerization inhibitors, supported heterogeneous catalysts, and building blocks for plasmonic devices. First, we investigate the interaction of hydrogen-terminated silicon nanoparticles (H-SiNPs) with Karstedt's catalyst and report a room‑temperature synthesis of Pt-coated SiNPs with highly tunable Pt loading. Analysis of the Pt on-Si ensemble reveals surface-bound Pt(II) on SiNPs which can undergo ligand exchange. Upon calcination, Pt-loaded SiNPs catalyze the hydrogenation of phenyl acetylene, and the SiNP …

Chemical Approach To Tire Mark Analysis, John Lucchi

Graduate Thesis and Dissertation 2023-2024

Fatal accidents on the road are an unfortunate daily occurrence, with almost 30,000 deaths resulting from hit-and-runs in the USA between 2006 and 2021. The identification of the driver responsible for this road crime can become a challenge. Nonetheless, the accident scene provides a large amount of trace evidence that can prove critical to this matter, one of them being the tire marks. While traditional tire mark analysis is full of physical information helping the reconstruction of the event, additional information can be extracted from the rubber left during the braking event. Each tire model is manufactured with a specific …

System Wide Analysis And Determination Of Accuracy, Precision, And Repeatability Of A Custom Prism Coupling Refractometry Instrument, Andrew W. Howe

Graduate Thesis and Dissertation 2023-2024

New optical designs have necessitated using refractive index data that is accurate to the third and fourth decimal points. Prism coupling refractometry could be attractive for this task because of a combination of factors. It allows for a direct assessment of the refractive index like interferometry or the minimum deviation method while being quick and convenient, like Kramers-Krönig analysis and spectroscopic ellipsometry. However, the accuracy, precision, and repeatability of this technique have not been revisited recently in the literature. This thesis seeks to identify the critical features of this technique that define its uncertainties and then provides some initial improvements …

Optical Characterization Of Liquids: Refractive Index And Raman Gain Coefficient Measurements, Cesar A. Lopez-Zelaya

Graduate Thesis and Dissertation 2023-2024

Novel technologies capable of generating wavelengths not accessible with typical laser gain media have been among the primary drivers of the field of nonlinear optics. Here, we are interested in the linear and nonlinear properties of liquids beyond the visible spectrum, motivated in part by their use as core materials in optical fibers. Given their dispersion, nonlinearities, transparency, and ability to be mixed, liquids show potential for exploiting in-fiber nonlinear phenomena for developing the new generation of low cost, size, weight, and power wavelength-agile fiber-laser sources. For the design, modeling, and experimental realization of these liquid-core fiber laser sources, proper …

Determination Of Damage Initiation Mechanisms In Aerospace Alloys Due To Stress Corrosion Cracking Via In-Situ Microscale Characterization Techniques, Remelisa Esteves

Electronic Theses and Dissertations, 2020-2023

Aluminum alloys are used on aerospace vehicles due to their high strength-to-weight ratio, formability and machinability. However, they become vulnerable to stress corrosion cracking (SCC) during their service life. SCC is primarily caused by the material's stress condition, a suitable corrosive environment and material susceptibility. It is also influenced by a mixture of electrochemical, mechanical, and chemical factors. Due to the complexity of SCC, tools with better resolution and sensitivity are needed to better understand the impact and interaction of the contributing factors. A vast amount of research has been done to study SCC behavior, but the scale of characterization …

Error Rate Determination Of Latent Print Chemistry Via 1d And 2d Gas Chromatography, Jessica Kindell

Electronic Theses and Dissertations, 2020-2023

Latent print evidence collected from crime scenes are analyzed and compared by examiners using the ACE-V protocol (Analysis, Comparison, Evaluation-Verification) to identify potential suspects. However, smudged and poor-quality prints, usually deemed inconclusive, could be utilized for source association or discrimination based on the chemistry of the oils and sweat that comprises the latent print residue (LPR). For this research, LPRs were collected from various places on the face and analyzed via two-dimensional gas chromatography-mass spectrometry (2D GC-MS), one-dimensional (1D) GC-MS, and direct analysis in real time-high resolution mass spectrometry (DART-HRMS). LPR recovery with two common sample preparation methods, derivatization and …

High-Efficieny Ultrafast Mid-Infrared Source For Strong Field Science, Fangjie Zhou

Electronic Theses and Dissertations, 2020-2023

The potential of high-energy sources within the mid-infrared region (3-8 μm) has garnered significant attention for diverse research and industrial applications. Millijoule pulses extending beyond 3 μm can facilitate the production of x-rays with photon energies in the keV range through high harmonic generation (HHG). These high-energy x-ray pulses enable the characterization of electron dynamics within molecules and condensed matter materials. Additionally, the atmospheric transmission window between 3-5 μm allows lasers within this spectral range to deliver energy efficiently to distant targets via optical filaments without divergence, highlighting promising prospects for defense applications. In contrast to laser amplifiers, which are …

Patterns Of Risk Behaviors And Their Value: A Latent Class Growth Modeling Approach, Anthony Naranjo

Graduate Thesis and Dissertation 2023-2024

The current body of individual risk behavior research has been mainly driven by two streams of literature. Stable risk researchers propose individuals tend to display similar risk behaviors across time and situations due to individuals' underlying propensity to either engage in risk averse or risk seeking behaviors. Changeable risk researchers have sought out to examine variability in risk behaviors due to factors such as personality and contextual characteristics. However, might it be the case that there are subgroups of individuals who may be more prone to display static risk behaviors and other subgroup whose risk behaviors are more amendable? To …

Classification Of Adult Income Using Decision Tree, Roland Fiagbe

Data Science and Data Mining

Decision tree is a commonly used data mining methodology for performing classification tasks. It is a tree-based supervised machine learning algorithm that is used to classify or make predictions in a path of how previous questions are answered. Generally, the decision tree algorithm categorizes data into branch-like segments that develop into a tree that contains a root, nodes, and leaves. This project seeks to explore the decision tree methodology and apply it to the Adult Income dataset from the UCI Machine Learning Repository, to determine whether a person makes over 50K per year and determine the necessary factors that improve …

Professional Development For Graduate School: Eportfolio And Networking, Wesley Lim

High Impact Practices Student Showcase Fall 2023

The development of an ePortfolio offers a digital introduction during networking events in an increasingly technology-driven society. Throughout one semester in Biomedical Sciences Careers, MCB 3933, I developed an ePortfolio with components like a resume, personal statement, individual development plan, and elevator speech. In my ePortfolio, I had three areas of focus that showcased my highlights and skills in my undergraduate education: the academic skill sets I developed, my relevant research experiences, and my time as a teaching assistant for multiple courses.

As part of the course, students were required to contact at least four people in their desired field …

Project Nur: Illuminating Lives Through Islamic Society's Community Service In Central Florida, Adam Bawatneh

High Impact Practices Student Showcase Fall 2023

This poster presents an in-depth exploration of my service experience at the Islamic Society of Central Florida (ISCF), where I have been serving as the head chef for the Family Night event. It delves into the challenges and triumphs encountered during my service, particularly in light of the recent conflict in Palestine. The poster also reflects on the personal growth and leadership development I have experienced throughout this journey.

Optical Design Study Of A High-Resolution Spectrograph Utilizing Photonic Lanterns For A Large Fiber Array Telescope, Richard D'Alo

Graduate Thesis and Dissertation 2023-2024

Large area fiber array telescopes are a relatively modern development in the long history of telescope design and effectively create a single large equivalent aperture by combining many smaller unit telescopes at a fraction of the cost. In this study a spectrograph optical design is demonstrated that utilizes photonic lanterns in the input fiber feed for the Large Fiber Array Spectroscopic Telescope (LFAST) design concept, where photonic lanterns provide a simplified approach to the fiber feed originally proposed for LFAST. Conservation of etendue is applied to derive the relationship between slit size and photonic lantern ratio, and classical echelle spectrograph …

Role Of Vitamin D, Folate, And Cobalamin Deficiency In Mycobacterium Avium Paratuberculosis Infection And Inflammation, Joseph Vaccaro

Electronic Theses and Dissertations, 2020-2023

Vitamin D, folate, and cobalamin (vitamin B12) are crucial micronutrients in human physiology that are necessary for healthy calcium, phosphorus, and single-carbon metabolism. Recent studies have indicated that these vitamins also affect the inflammatory response in ways unrelated to their well-characterized deficiencies. Accordingly, analysis of their effect on chronic inflammatory diseases like Crohn's disease (CD) is warranted. This investigation examines the effects of vitamin deficiency on macrophages and intestinal epithelial cells upon exposure to Mycobacterium avium paratuberculosis (MAP,) a pathogen capable of triggering CD, to model the inflammatory response in clinical CD patients. ELISA analysis of CD patient plasma established …

Dormant Propagules In Demographic Studies: A Recurrent Bias And Potential Solutions, Federico Borghesi

Graduate Thesis and Dissertation 2023-2024

In the face of unprecedented anthropogenic change, we increasingly turn to emergent technologies and extensive data sets for solutions that complement much needed systemic changes in our societies. These technological solutions, however, must be approached with care. We must recognize and address biases in the way data has been accumulated. In demographic studies, dormant life stages, such as seed banks, and other cryptic factors have often been neglected. The potential consequences of these omissions have been extensively described in the literature. In the first chapter, I analyze patterns of seed bank omissions in demographic models, finding unjustified omissions are widespread …

The Dynamical Measurement And Modeling Of Metacognition And Engagement Using Self-Report And Multimodal Data With Advanced Learning Technologies, Megan Wiedbusch

Electronic Theses and Dissertations, 2020-2023

Interdisciplinary research has demonstrated that learning and problem solving with advanced learning technologies (ALTs) such as intelligent tutoring systems, simulations, hypermedia, serious games, and virtual reality can promote and foster the development of 21st century skills (e.g., collaboration, problem solving, self-regulated learning) by measuring and using the interactions between cognitive, affective, metacognitive, motivational, and social (CAMMS) processes. Interdisciplinary researchers focused on self-regulated learning (SRL) have developed several theoretical models which model students' CAMMS processes and their learning behaviors. However, when empirically testing these models, researchers face complicated methodological decisions around modeling, measuring, processing, and analyzing student data. Many of these …

A Theoretical Study Of Elementary Processes In Interstellar Plasma, Joshua Forer

Graduate Thesis and Dissertation 2023-2024

Interstellar plasma — interstellar clouds in particular — play an important role in determining the structure and evolution of galaxies. Understanding the time evolution of such plasmas requires knowledge of the chemical processes that drive their dynamics. Two processes are studied in this dissertation: radiative electron attachment (REA) via dipole-bound states (DBSs) and dissociative recombination (DR). Of the several hundred molecules detected in the interstellar medium, only eight anions have been detected: CN-, C3N-, C5N-, C7N-, C4H-, C6H-, C8H-, and C10H-. Their production mechanism is not well known; REA was suggested as a possible formation pathway, but previous theoretical studies …

Algorithms And Variations On The Positional Burrows-Wheeler Transform And Their Applications, Ahsan Sanaullah

Electronic Theses and Dissertations, 2020-2023

In this dissertation, we develop algorithms and variations on the Positional Burrows-Wheeler Transform (PBWT). The PBWT is a data structure that stores M binary strings of length N while allowing efficient search. We develop the dynamic-PBWT (d-PBWT). The d-PBWT is a variation of the PBWT that allows its relevant algorithms to run with unchanged time complexity, but also allows efficient insertion and deletion of haplotypes. We provide insertion and deletion algorithms on the PBWT with average case O(N) time complexity. We also improve upon the query algorithms for the PBWT. Durbin described a set maximal match query algorithm on the …

Spatial Ensemble Distillation Learning Based Real-Time Crash Prediction And Management Framework, Md Rakibul Islam

Graduate Thesis and Dissertation 2023-2024

Real-time crash prediction is a complex task, since there is no existing framework to predict crash likelihood, types, and severity together along with a real-time traffic management strategy. Developing such a framework presents various challenges, including not independent and identically distributed data, imbalanced data, large model size, high computational cost, missing data, sensitivity vs. false alarm rate (FAR) trade-offs, estimation of traffic restoration time after crash occurrence, and real-world deployment strategy. A novel spatial ensemble distillation learning modeling technique is proposed to address these challenges. First, large-scale real-time data were used to develop a crash likelihood prediction model. Second, the …

Acausal Modeling Of Wind Turbines With Validation And Control Studies, Kazi Ishtiak Mohsin

Graduate Thesis and Dissertation 2023-2024

This thesis involves the modeling, validation, and control studies of a Control-Oriented, Reconfigurable, and Acausal Floating Turbine Simulator (CRAFTS), that is currently under development. CRAFTS uses Modelica®, an object-oriented, declarative, multi-domain modeling language for physical system modeling in the Dymola environment. The CRAFTS simulator facilitates rapid dynamic simulation of wind turbines with various model variants and enables control co-design.

A major emphasis of this thesis is in the validation of the CRAFTS simulator for a 15-MW land-based wind turbine through several test cases. These test cases were collaboratively developed in conjunction with other participating research entities. CRAFTS has undergone rigorous …

Reconstructing 3d Humans From Visual Data, Ce Zheng

Graduate Thesis and Dissertation 2023-2024

Understanding humans in visual content is fundamental for numerous computer vision applications. Extensive research has been conducted in the field of human pose estimation (HPE) to accurately locate joints and construct body representations from images and videos. Expanding on HPE, human mesh recovery (HMR) addresses the more complex task of estimating the 3D pose and shape of the entire human body. HPE and HMR have gained significant attention due to their applications in areas such as digital human avatar modeling, AI coaching, and virtual reality [135]. However, HPE and HMR come with notable challenges, including intricate body articulation, occlusion, depth …

Safety Considerations For Setting Variable Speed Limits On Freeways, Md Tarek Hasan

Graduate Thesis and Dissertation 2023-2024

This thesis focuses on evaluating the appropriate speed at which vehicles should travel under different traffic conditions on freeways and its impact on crash frequency. The common belief is that the lower speed results in fewer crashes as reduced speed provides drivers with more time to react effectively and avoid collisions. However, this perspective overlooks the interplay among traffic speed, average spacing between consecutive vehicles, and the distance available for stopping a vehicle. Hence, we propose a safety parameter termed ‘Safety Correlate' (SCORE), which is defined as the proportion of average spacing relative to the stopping distance. To determine the …

Understanding Workforce Agility At Nasa Kennedy Space Center, Ledlyne H. Vazquez

Graduate Thesis and Dissertation 2023-2024

This study aims to define workforce agility via a literature review and a conducted research survey of the Kennedy Space Center (KSC) Engineering workforce. The survey results will help us determine the workforce agility of the KSC engineering team and understand what has allowed them to transition from the Space Shuttle Program to the new Exploration Ground System (EGS) program. Structural Equation Modeling was used to develop a model of relationships to test the hypotheses. The results show that organizational practices and psychological empowerment significantly support workforce agility. The implications of this study for understanding the characteristics of workforce agility …

Social Media-Based Crisis Communication: Analysis Of Twitter Data From Local Agencies During Hurricane Irma, Naiyara Noor

Electronic Theses and Dissertations, 2020-2023

As social media platforms have become vital means of communications, it has become imperative for emergency managers and policy makers to understand how people are interacting with different agencies on these platforms for enhancing community response coordination during disasters. Although many public agencies have already adopted social media platforms for crisis communication purposes, empirical evidence on whether and how these agencies are effectively engaged on these platforms is lacking. This research aims to examine crisis communication activities of a variety of agencies on Twitter in response to Hurricane Irma in 2017. In this study, we analyzed 13,353 hurricane-related tweets posted …