Digital Commons Network^™

Analyzing Fluctuation Of Topics And Public Sentiment Through Social Media Data, Haoyue Liu

Dissertations

Over the past decade years, Internet users were expending rapidly in the world. They form various online social networks through such Internet platforms as Twitter, Facebook and Instagram. These platforms provide a fast way that helps their users receive and disseminate information and express personal opinions in virtual space. When dealing with massive and chaotic social media data, how to accurately determine what events or concepts users are discussing is an interesting and important problem.

This dissertation work mainly consists of two parts. First, this research pays attention to mining the hidden topics and user interest trend by analyzing real-world …

Computation Of Risk Measures In Finance And Parallel Real-Time Scheduling, Yajuan Li

Dissertations

Many application areas employ various risk measures, such as a quantile, to assess risks. For example, in finance, risk managers employ a quantile to help determine appropriate levels of capital needed to be able to absorb (with high probability) large unexpected losses in credit portfolios comprising loans, bonds, and other financial instruments subject to default. This dissertation discusses the computation of risk measures in finance and parallel real-time scheduling.

Firstly, two estimation approaches are compared for one risk measure, a quantile, via randomized quasi-Monte Carlo (RQMC) in an asymptotic setting where the number of randomizations for RQMC grows large, but …

Brainless But Smart: Investigating Cognitive-Like Behaviors In The Acellular Slime Mold Physarum Polycephalum, Subash Kusum Ray

Dissertations

Evolutionary pressures to improve fitness, have enabled living systems to make adaptive decisions when faced with heterogeneous and changing environmental and physiological conditions. This dissertation investigated the mechanisms of how environmental and physiological factors affect the behaviors of non-neuronal organisms. The acellular slime mold Physarum polycephalum was used as the model organism, which is a macroscopic, unicellular organism, that self-organizes into a network of intersecting tubules. Without using neurons, P. polycephalum can solve labyrinth mazes, build efficient tubule networks, and make adaptive decisions when faced with complicated trade-offs, such as between food quality and risk, speed and accuracy, and exploration …

Stochastic Modeling Of Flows In Membrane Pore Networks, Binan Gu

Dissertations

Membrane filters provide immediate solutions to many urgent problems such as water purification, and effective remedies to pressing environmental concerns such as waste and air treatment. The ubiquity of applications gives rise to a significant amount of research in membrane material selection and structural design to optimize filter efficiency. As physical experiments tend to be costly, numerical simulation and analysis of fluid flow, foulant transport and geometric evolution due to foulant deposition in complex geometries become particularly relevant. In this dissertation, several mathematical modeling and analytical aspects of the industrial membrane filtration process are investigated. A first-principles mathematical model for …

Optimizing Incentives For Systems With Heterogeneous Agents, Chen Chen

Dissertations

This dissertation explores new models and applications based on the game theory of incentives. This exploration starts with controlling an invasive insect problem to address one of the most significant challenges facing our forests, the invasion of the Emerald ash borer (EAB), a non-native, wood-boring insect that threatens to kill most ash trees in North America, through designing two new cost-sharing programs between the landowners and local governments. Ash trees are one of North America’s most widely distributed tree genera and a vital part of the green infrastructure of cities, where they provide residents with numerous social, economic, and ecological …

Performance Analysis Of The Dominant Mode Rejection Beamformer, Enlong Hu

Dissertations

In array signal processing over challenging environments, due to the non-stationarity nature of data, it is difficult to obtain enough number of data snapshots to construct an adaptive beamformer (ABF) for detecting weak signal embedded in strong interferences. One type of adaptive method targeting for such applications is the dominant mode rejection (DMR) method, which uses a reshaped eigen-decomposition of sample covariance matrix (SCM) to define a subspace containing the dominant interferers to be rejected, thereby allowing it to detect weak signal in the presence of strong interferences. The DMR weight vector takes a form similar to the adaptive minimum …

Low-Reynolds-Number Locomotion Via Reinforcement Learning, Yuexin Liu

Dissertations

This dissertation summarizes computational results from applying reinforcement learning and deep neural network to the designs of artificial microswimmers in the inertialess regime, where the viscous dissipation in the surrounding fluid environment dominates and the swimmer’s inertia is completely negligible. In particular, works in this dissertation consist of four interrelated studies of the design of microswimmers for different tasks: (1) a one-dimensional microswimmer in free-space that moves towards the target via translation, (2) a one-dimensional microswimmer in a periodic domain that rotates to reach the target, (3) a two-dimensional microswimmer that switches gaits to navigate to the designated targets in …

Artificial Neural Networks And Their Applications To Intelligent Fault Diagnosis Of Power Transmission Lines, Fatemeh Mohammadi Shakiba

Dissertations

Over the past thirty years, the idea of computing based on models inspired by human brains and biological neural networks emerged. Artificial neural networks play an important role in the field of machine learning and hold the key to the success of performing many intelligent tasks by machines. They are used in various applications such as pattern recognition, data classification, stock market prediction, aerospace, weather forecasting, control systems, intelligent automation, robotics, and healthcare. Their architectures generally consist of an input layer, multiple hidden layers, and one output layer. They can be implemented on software or hardware. Nowadays, various structures with …

Diagnostics Of Energy Release In Solar Flares With Radio Dynamic Imaging Spectroscopy, Yingjie Luo

Dissertations

Studies of the magnetic energy release and conversion process lie at the core of solar flare physics. Radio observations serve as a unique diagnostic method. In this dissertation, taking advantage of broadband radio dynamic imaging spectroscopy observations made by the Karl G. Jansky Very Large Array (VLA), studies are carried out on the flare energy release processes using different types of radio emissions.

The VLA is a general-purpose radio observatory located in New Mexico, which provides high-quality radio dynamic imaging spectroscopic observations with an ultra-fast time cadence. In the first study, stochastic decimetric radio spike bursts are observed by the …

Understanding The Role Of Magnetic Field Evolution In The Initiation And Development Of Solar Eruptions, Nian Liu

Dissertations

This dissertation aims to understand the initiation and evolution of solar eruptions. The essential science questions to answer include: What is the role of magnetohydro dynamic (MHD) instabilities and magnetic reconnection in triggering and driving eruptions? What are the role of Kink Instability (KI) and Torus Instability (TI) in determining the successful and failed eruptions? What is the thermal behavior of flare precursors in the initiation stage of solar eruptions? Finally, how does the corona magnetic field respond to the flare eruptions? The dissertation mainly includes the following studies.

First, this dissertation presents a multi-instrument study of the two precursor …

Towards Ensuring Integrity And Authenticity Of Software Repositories, Sangat Vaidya

Dissertations

The software development process comprises a series of steps known as a software supply chain. These steps include managing the source code, testing, building and packaging it into a final product, and distributing the product to end users. Along this chain, software repositories are used for different purposes such as source code management (Git, SVN, mercurial), software distribution (PyPI, RubyGems, NPM) or for deploying software based on container images (Harbor, DockerHub, Artifact Hub). In the recent past, different types of repositories have increasingly been the target of attacks. As such, there is a need for mechanisms to ensure integrity and …

Critical Mass Of Women On Biotech Corporate Boards And Its Implication For Firm Performance: A Mixed Method Explanatory Sequential Study, Shesh Sharma

Dissertations

This study examined the influence of demographic, functional, and cognitive diversities on firm performance of North American Biotech companies using a mixed method explanatory sequential approach. One-year cross-sectional data of 100 companies was analyzed followed by purposeful semistructured interviews with eight board members from the dataset. The combined results resolved several ambiguities present in the literature regarding board selection, composition, and the correlation of board diversity with firm performance. This study used the well-known market-based financial metric Tobin’s Q to measure firm performance.

The quantitative results showed a dichotomous relationship between gender ratio and Tobin’s Q based on a theoretically …

Parameter Selection In Fully Homomorphic Encryption Schemes And Fhe Applications, Cavidan Yakupoglu

Dissertations

Quantum computing has been gaining momentum as a result of recent technological advances. Existing cryptographic systems rely on the difficult problems that can be solved by sufficiently powerful quantum computers. As the quantum age approaches, the desire to discover new difficult problems that cannot be solved by quantum systems has increased. Lattice-based cryptography is a prominent tool for the post-quantum era that facilitates the implementation of encryption systems for practical applications.

The Learning with Error (LWE) and Ring-LWE problems introduce new lattice hardness assumptions that have been incorporated into public-key cryptosystems to facilitate the implementation of numerous privacy-enhancing applications. Fully …

A Study Of Red Snapper (Lutjanus Campechanus) Ecology In The Northern Gulf Of Mexico And The Effect Of Variable River Outflow Using Stable Isotope Analysis Of The Food Web And Eye Lenses, Caitlin C. Slife

Dissertations

In the Mississippi Bight and surrounding waters, river outflow impacts the basal resources of the Red Snapper food web, altering carbon sources and impacting prey and predator isotopes. In this study, the impact of riverine outflow on nutrients, particulate organic matter (POM), and physical water parameters on Red Snapper and their food web was analyzed using stable isotope and stomach content analysis over 5 years. The Mississippi, Pearl, Pascagoula, and Mobile rivers were included in the analysis of river impact. The Mississippi and Mobile rivers were found to significantly impact nutrients and POM in the region. River outflow was also …

Brenno Blauth’S Compositional Style Elements: A Study On The Sonata For Flute And Piano, T.5., Thiago Bohm Bottega

Dissertations

The Sonata para Flauta e Piano, T.5, by Brenno Blauth (1931-1993), is a standard of the Brazilian flute repertoire. This document studies its folk and Brazilian popular music elements in order to better understand Blauth’s compositional rationale.

In 1959 Blauth was responsible for the creation of the group Movimento Musical Renovador. Based in Rio de Janeiro, MMR gathered renowned composers and performers with the goal of promoting Brazilian classical music. Chapter III is dedicated to the group’s initiatives, taking its political and cultural contextualization into account.

Chapter IV is dedicated to the study of Blauth’s compositional style shifts …

Impact Of An Active Learning Intervention On Student Success In An Introductory-Level Biology Course, Cynthia Littlejohn

Dissertations

Large enrollment introductory-level courses with high rates of students receiving a D, F, or withdrawing have been identified within higher education as gateway courses. Students not successfully completing these courses are disproportionately represented by historically and continually marginalized populations, such as low-income, poorly represented ethnic groups, and first-generation students. A form of blended learning called the flipped class model is becoming increasingly prevalent in gateway courses. A flipped class design may reduce the cognitive load by allowing time for processing information before class while cooperative learning may result in a collective working memory effect where social interactions may serve to …

Data Collection And Machine Learning Methods For Automated Pedestrian Facility Detection And Mensuration, Joseph Bailey Luttrell Iv

Dissertations

Large-scale collection of pedestrian facility (crosswalks, sidewalks, etc.) presence data is vital to the success of efforts to improve pedestrian facility management, safety analysis, and road network planning. However, this kind of data is typically not available on a large scale due to the high labor and time costs that are the result of relying on manual data collection methods. Therefore, methods for automating this process using techniques such as machine learning are currently being explored by researchers. In our work, we mainly focus on machine learning methods for the detection of crosswalks and sidewalks from both aerial and street-view …

Three Essays On Social Networks And Schools, Yunzheng Zheng

Dissertations

Researchers have been increasingly interested in the phenomenon of social networks in education, a research area that provides more opportunities to study the relationships among individuals or organizations in our educational system. The goal of this dissertation was to understand the effect of various social networks on outcomes by investigating various relationships in the educational system. To achieve the goal, three distinct, but related, essays comprised this dissertation.

In the first essay, I examined the effects of interschool networks on student achievement. By using the data collected from the High Impact Leadership (HIL) program and employing the hierarchical linear model …

Pathways To Success For African American Students At Predominately White Institutions: A Qualitative Study Exploring Academic Readiness, Jeffery Jackson

Dissertations

African American students’ completion of post-secondary education is among the lowest of any other subgroup in higher education (Banks & Dohy, 2019; Broom, 2018; Carter- Francique et al., 2015; Cokley et al., 2016; Dulabaum, 2016; Karkouti, 2016; Moragne-Patterson & Barnett, 2017; Strayhorn, 2017). This study focuses on addressing this problem by exploring the academic and social experiences of African American college students who persisted at a regional predominantly White institution (PWI) in the Midwest and secure information that can be used to improve their graduation rates.

To address this issue, this study is designed to explore initiatives and practices that …

Studying The Synthesis Of 196Hg At Astrophysically Relevant Energies Through The Measurement Of Capture Reaction Cross-Sections Of (P, Γ) (P, N) And (P, Α) Reactions, Khushi Bhatt

Dissertations

Understanding the origin of all the chemical elements is an important question for the nuclear-astrophysics community. There are many unanswered questions like: What astrophysical events are responsible for the synthesis of what particular chemical elements? How many different elements were made in total? What is the abundance of each synthesized element? etc. Currently, scientists are largely depending upon theory and simulations to define nuclear and astrophysical reaction. This makes it critical to have accurate experimental nuclear physics data to input in astrophysical theoretical models. However, out of more than 20000 reactions involved in these calculations, only a very few are …

Peridynamic Modeling Of Crack Propagation In Brittle Materials With Electromechanical Coupling, Semsi Coskun

Dissertations

The bond-based peridynamics (BB-PD) is a widely used peridynamic model in the literature. Despite Poisson's ratio restriction, it still serves as a powerful tool to solve challenging engineering problems with a relatively cheap computational cost. Consider the Poisson ratio of the material does not deviate from the ones that BB-PD can model. In that case, it becomes advantageous to use the BB-PD compared to other PD models in terms of computational cost and simplicity. However, the BB-PD suffers from the so-called surface or skin effect where the material response at boundaries becomes softer than the bulk material points. As a …

A Mixed Methods Investigation Of Third Grade Academic Achievement Data: Pre- And Post-Google Chromebook Usage In A Midwest Elementary School, Brittany Powell

Dissertations

Technology in the educational setting has evolved drastically over the last few decades and continues to currently evolve. As technology advances, best practices for teaching and learning, standardized testing, and curriculum also must evolve. The purpose of this study aimed to fill the gap of the lack of research regarding the possible differences in academic achievement data, pre- and post-Google Chromebooks usage. The researcher investigated educators’ and administrators’ perceptions of technology by conducting inperson interviews at the conclusion of the two-year study. The analysis of qualitative data, gathered from all interviews and researcher journal entries, fell into various thematic categories, …

Principals’ Definition And Identification Of Critical Thinking In Teacher Practices, Carmen Aumber Polka

Dissertations

Principals are teacher evaluators and, therefore, need a clear definition and identification of critical thinking in teacher practices to increase their impact on teacher effectiveness and student critical thinking outcomes. Beyond teacher evaluations, principals are responsible for supporting and developing teachers in their instructional practices (Davis et al., 2005) and for enhancing teachers’ pedagogical skills (Marzano et al., 2011). This instrumental case study explored how 12 principals, who use the Colorado State Model Evaluation System (CSMES) to evaluate critical thinking teacher practices, define critical thinking, and identify critical thinking utilized in teacher practices. Participants were purposefully selected from this Colorado …

Probing The Equation Of State Of Neutron Stars With Heavy Ion Collisions, Om Bhadra Khanal

Dissertations

The equation of state (EOS) is a fundamental property of nuclear matter, important for studying the structure of systems as diverse as the atomic nucleus and the neutron star. Nuclear reactions, especially heavy-ion collisions in the laboratories, can produce the nuclear matter similar to those contained in neutron stars. The density and the momentum dependence of the EOS of asymmetric nuclear matter, especially the symmetry energy term, is widely unconstrained. Finding appropriate constrains, especially at higher densities of the nuclear matter, requires the development of new devices, new experimental measurements as well as advances in theoretical understanding of nuclear collisions …

Entre Dos Mundos: Understanding The Experiences Of Latinx Adolescent Language Brokers, Miranda Kristine Martino

Dissertations

Every day, across the United States, there are families who rely on their children to perform the essential task of facilitating communication between themselves and others who do not share their language; this process is referred to as language brokering. Eleven participants who identified as Latinx child language brokers were interviewed. The purpose of this study was to explore the stories of these youth to better understand how they came to be language brokers in their families, their perspectives on their roles within their families and their culture, and the perceived positives and challenges of this practice. From these lived …

Time-Dependent Photoionization Modeling Of Warm Absorbers In Active Galactic Nuclei, Dev Raj Sadaula

Dissertations

Warm absorber spectra are bound-bound and bound-free absorption features, seen in the X-ray and UV spectra from many active galactic nuclei (AGN). The widths and centroid energies of these features indicate they occur in outflowing gas moving with hundreds to thousands of km/s. Depending upon the energy and momentum of the outflow, it can affect the gas within the host galaxy. Thus, warm absorbers’ mass and energy budgets are of great interest. Estimates for these properties depend on models that connect the absorption features' observed strengths with the density, composition, and ionization state of the absorbing gas. Such models assume …

Evidence For An Early Saginaw Lobe Ice Retreat And Drainage Adjustments Across Southern Michigan, Usa, Nathan Erber

Dissertations

The Saginaw lobe of the Laurentide Ice Sheet (LIS), flowed out of Saginaw Bay, across Lower Michigan and into northern Indiana. As it retreated, the Saginaw lobe deposited the Sturgis moraine, a recessional moraine of the lobe in southern Michigan. Positioned to the west and east of the Saginaw lobe were the Lake Michigan and Huron-Erie lobes, respectively. These lobes retreated across the region asynchronously, with the Saginaw lobe retreating first. The asynchronous behavior of the lobes allowed for the Lake Michigan and Huron-Erie lobes to overprint and alter landscapes once occupied by the Saginaw lobe ice.

The Kalamazoo moraine, …

Esports Curricula In U.S. Post-Secondary Institutions: A Case Study, Debra L. Bell

Dissertations

Although the concept of Esports competency has been widely recognized, it is not yet well understood by the various educational institutions that have started offering certification programs in this field. This study aims to provide a comprehensive analysis of the multiple principles that have been established to promote this specialization.

The increasing popularity of gaming and esports has led to the development of a wide range of educational programs that are geared toward addressing the needs of the future workforce. Although the goal of these programs is to provide a comprehensive view of the various facets of this field, the …

Evidence-Based Equity In Chemical Education, Anna Margiotta

Dissertations

Using Constructivist Grounded Theory (CGT) and reflexive Thematic Analysis (TA) methods, the purpose of this case study was to construct theory about equity for students studying chemistry at public universities in Colorado. Interviews with students (N=12), chemistry instructors (N=9), and equity practitioners (N=9) as well as observations of chemistry classes (N=42) were collected. Along with these interview transcripts and in-class observations, surveys completed by participants were also included as data. Journal entries of a reflexive or memoing nature were written as part of the data analysis procedures. With these data, I explored potential methods of equitable change in chemistry instruction …

Opportunities To Learn The General Education Curriculum: Literacy Instruction For Students With Significant Support Needs In Inclusive Settings, Heather Leigh Fitzpatrick

Dissertations

Students with significant support needs (SSN) have often been denied the breadth and depth of literacy instruction compared to their nondisabled peers. However, exposure to academic literacy increases when students with SSN are educated with their peers without disabilities within inclusive settings. While exposure is the first step to accessing grade level content, it does not necessarily mean that students with SSN will have the same opportunities to learn (OTL). Students with SSN require additional adaptions and supports to learn and make progress in the general education setting. Conversely, these supports are not always provided or used effectively to meet …