Digital Commons Network^™

The Relationship Between Biofouling Adhesion And Frequency Of Mechanical Cleaning To Control The Recruitment To Clear Coatings, Dylan Thomas Eggers

Theses and Dissertations

There is a need to control biofouling on sensors and transparent windows in the marine environment. Clear silicone coatings offer a method to reduce the adhesion strength of marine organisms to the surface, however, these also require mechanical cleaning to maintain the surfaces free of fouling. This research evaluated the performance of eighty seven formulations and took the top two candidates to investigate a) the frequencies of wiping required by a brush to maintain two coatings and uncoated glass surfaces free of fouling and b) the effects of clear silicone coatings fouling release properties on required frequencies. The panels were …

Underwater Image Enhancement: A Pipeline For Underwater Computer Visions, Humberto Lebron Rivera

Theses and Dissertations

Ocean exploration has surged in popularity and significance in recent years, including diverse areas like maritime archeology, underwater resources, and submerged structure inspection. The activities mentioned above heavily depend on vision and imagery, a challenge in the unpredictable marine world. This thesis presents a conditional generative adversarial network model for image-to-image translation problems. We designed and trained the model with the end goal of enhancing underwater images. Five metrics were employed for validation to quantify our model’s resulting enhanced images. By doing so, we aim to establish a pipeline that can leverage aerial computer vision algorithms for marine applications.

Our …

How Students Learn: Examining The Differences In Learning Strategies Between Flight And Nonflight Students, Jennifer A. Torres

Theses and Dissertations

The purpose of this study was to determine if there were any differences in learning strategies between undergraduate flight and nonflight students attending a 4-year university that offered a Part 141 flight training program. Learning strategies were measured using Panadero et al.’s (2021) 30-item Deep Learning Strategies Questionnaire and its four subscales—Basic Learning Self-Regulation Strategies, Visual Elaboration and Summarizing Strategies, Deep Information Processing Strategies, and Social Learning Self-Regulation Strategies—all of which were the dependent variables. The primary independent variable was group membership, but the study also incorporated two covariates—self-efficacy and intrinsic value—which were measured using the respective subscales of Pintrich …

Path Planning Development Framework For Mobile Robots, Lauren-Ann Elizabeth Graham

Theses and Dissertations

Planetary exploration relies on methods of path planning to achieve autonomous navigation in hazardous environments. Simulating harsh terrain, real-time varying physics, and robotics applications is vital for testing control algorithms here on Earth. Robotics Operating System (ROS) is a set of software libraries and tools that allow you to build and simulate robotic applications. Utilizing ROS, Gazebo, and Blender, a rough terrain simulation framework is created to explore and compare path planning algorithms using various desired robots and maps. ROS supports multiple path planning algorithms given its open-source abilities. This research focuses on path planning implementation of Proportional-Integral-Derivative (PID) control …

Gpu Based Monte Carlo Estimation Of Eddy Current Losses In Electromagnetic Coil-Core System, Adwaith Ravichandran

Theses and Dissertations

A novel parallelizable probabilistic approach to model eddy currents in AC electromagnets is presented in this research. Consequently, power loss associated with the formation of these eddy currents is estimated and validated using experimental data. Furthermore, predicting the effect of ferromagnetic alternating field enhancement on power loss in the source excitation winding has been an active area of research. Unlike a stationary field, an alternating sinusoidal field diffuses partially into the ferromagnetic material leading to a predictably sub-optimal field enhancement. To model these physics, finite element techniques employ nonlinear iterative solvers which are time consuming. A novel method is developed …

Project Thetis: A Low-Cost, Low-Profile Inertial Data Logger, Braidan Duffy

Theses and Dissertations

This thesis details the design, testing, calibration, and verification of a nine degree of freedom inertial measurement data logger for use with floating bodies. The instrument was conceived to address limitations of equipment used in classes within the Ocean Engineering department at Florida Institute of Technology. By meeting with several stakeholders and end users, a series of stakeholder requirements, capabilities, and component-level requirements were de- veloped that informed the design constraints. There were several hardware iterations of the board, culminating in Revision F5 which was extensively tested and proven. The design was inspected after testing concluded to determine which capabilities …

Patterns In Winter Stonefly Distribution Along A River Continuum And Land-Use Gradient In Northwest Arkansas Streams, Zachary Tipton

Graduate Theses and Dissertations

Freshwater ecosystems are facing a crisis with extinction rates of aquatic species exceeding those of their terrestrial counterparts by up to fivefold. This decline is predominantly attributed to evolving land use patterns within watersheds, leading to chemical and physical transformations in freshwater habitats. Northwest Arkansas (NWA) represents one of the fastest-growing regions in the United States, undergoing substantial shifts in land use. Consequently, the status of aquatic life in this region remains uncertain. Addressing this concern, the latest Arkansas Wildlife Action Plan emphasizes the necessity of distribution and population data to guide conservation efforts for Species of Greatest Conservation Need …

A Framework Of Flow Models For The Development And Testing Of Cardiovascular Devices, Megan Laughlin

Graduate Theses and Dissertations

Cardiovascular disease (CVD) is the leading cause of death worldwide and its treatment continues to improve due to the advancement of innovative cardiovascular medical devices. In vitro and in silico models serve to replicate the in vivo environment for the development and testing of these devices prior to using animals for testing, and eventually humans in clinical trials. However, limitations related to these models exist in multiple areas including general, cardiac, and venous applications. Specifically, current gaps have been identified with customizable, tissue-mimicking phantoms (general), 2D Blood Speckle Imaging (BSI) (cardiac) and a bioprosthetic venous valve (venous). This dissertation focuses …

Impact Of Reducing Ammonia Concentration By Ozone Technology And Its Potential Improvement On Broiler Performance, Odilpio Quintana Ortega

Graduate Theses and Dissertations

The employment of ozone in livestock production as a means of mitigating ammonia is used for enhancing air quality within animal confinement facilities, such as swine or poultry barns. Ammonia is a byproduct of animal excrement. Elevated ammonia concentrations can adversely affect the well-being of both animals and humans. The aim of this thesis was to investigate the effects of Ozone Technology Machine Unit (OTMU) utilization in poultry barns regarding ammonia concentration and its potential benefit in terms of broilers performance and welfare. In recent years, there has been a significant boom in technological advances. New devices that help mitigate …

Habitat Associations Of Plains Spotted Skunk (Spilogale Interrupta) Across The Plains Ecoregion. And The Landcover Occupancy Models Of The Gray Fox (Urocyon Cinereoargenteus) In The Southeastern Plains Region In Arkansas, Michael Shaw

Graduate Theses and Dissertations

Much of the landscape of the United States has been altered by humans, leading to the eradication of most populations of large mammalian predators. Consequently, many species of mammalian mesopredators (medium-sized mammalian predators) have come to dominate the landscape. Species such as the gray fox (Urocyon cinereoargenteus) may appear to be on the rise and doing well due to their widespread range, but at a local scale may need monitoring and less is known in areas of its range. Others such as the plains spotted skunk have a wide range across the plains but are on the decline even with …

Deep Learning Frameworks For Accelerated Magnetic Resonance Image Reconstruction Without Ground Truths, Ibsa Kumara Jalata

Graduate Theses and Dissertations

Magnetic Resonance Imaging (MRI) is typically a slow process because of its sequential data acquisition. To speed up this process, MR acquisition is often accelerated by undersampling k-space signals and solving an ill-posed problem through a constrained optimization process. Image reconstruction from under-sampled data is posed as an inverse problem in traditional model-based learning paradigms. While traditional methods use image priors as constraints, modern deep learning methods use supervised learning with ground truth images to learn image features and priors. However, in some cases, ground truth images are not available, making supervised learning impractical. Recent data-centric learning frameworks such as …

The Study Of The Polarization Domains Of Mbe-Grown Barium Titanate Thin Films And Nanodots Using Pfm, Mohammad Zamani-Alavijeh

Graduate Theses and Dissertations

Polarization domains are the fundamental elements in ferroelectric materials that contribute to their properties. A natural polarization domain, which possesses a specific polarization direction or state, typically ranges in size from one unit cell to a few micrometers. Therefore, studying polarization domains requires the fabrication of materials and the measurement of ferroelectric properties at the nanoscale. In this study, molecular beam epitaxy (MBE) is employed to fabricate barium titanate (BTO) crystals, and piezoresponse force microscopy (PFM) is used to measure the properties of polarization domains at the nanoscale. In the beginning, this study identifies the reflection of high-energy electron diffraction …

3d Printed Microdialysis-Based Microsampling Probes, Patrick Pysz

Graduate Theses and Dissertations

This work will show the development of a fully 3D printed device platform in which a complex microsampling probe geometry is fabricated in a simple two-step process. This process includes the combination of 2-photon polymerization (2PP) and masked-stereolithography (MSLA). The cutting edge neurotechnology needed to monitor brain internal communication and will require multiple sensing modalities including temperature, pressure, electrophysiological, and optogenetics. Microsampling is an integrally important function for any future biosensing device platform as it allows for chemical delivery and unparalleled specificity through offline analysis of collection samples. Stereolithography (SLA) 3D printing has emerged as a powerful fabrication method capable …

Modeling The Peak Ground Acceleration And Assessing The Economic Loss And Casualty Due To Potential Earthquakes Of Various Magnitudes In The New Madrid Seismic Zone, Mahmud Afroz

Graduate Theses and Dissertations

The New Madrid Seismic Zone (NMSZ) is one of the active tectonic zones capable of producing big earthquakes in the southcentral USA. The objective of this study was to assess the economic losses and casualties that might be caused by various magnitudes of seismic events in the NMSZ. The manifestation is the estimation for each magnitude which is using the Peak Ground Acceleration (PGA) that might occur during an earthquake. It is calculated using an attenuation function that correlates the intensity of local ground movement, the earthquake magnitude, and the distance from its epicenter. The assessment of casualties was conducted …

Exploring The Interrelationships Among Structural Complexity, Multi-Trophic Biodiversity, And Ecosystem Productivity In Forested Ecosystems., Ayanna St. Rose

Graduate Theses and Dissertations

Forests play a pivotal role in sustaining global biodiversity and mitigating the global climate, as they serve as the primary refuge for terrestrial biodiversity and effectively capture and store atmospheric carbon dioxide. However, changing climate and land use are altering the geographic distribution, physical structure, and productivity of forested ecosystems that can have profound impacts on biodiversity conservation, forest productivity, and global climate. This dissertation contributes to our understanding of multifaceted interactions between the physical and biological structural complexity and ecosystem functions in forested landscapes across the United states by using openly available data from two national networks: the National …

Characterization Of Highly Doped N-Type And P-Type Silicon Carbide Ohmic Contacts, Tanner Rice

Graduate Theses and Dissertations

Silicon Carbide (SiC) is a rather new material that possesses unparalleled properties when compared to Silicon. Due to its larger band gap alongside other thermal properties, SiC can survive in hotter, more radiation intensive environments, whether that be within the crust of the earth or in the reaches of space. As a desirable semiconductor for these applications, CMOS is an especially important device due to its low power consumption. However, creating a good contact between the metal and semiconductor optimally requires two different metals for the n -type and the p-type semiconductor. This greatly increases the processing time, as separate …

Diminishing Creative Returns: Predicting Optimal Creative Performance Via Individual Differences In Executive Functioning, Kent F. Hubert

Graduate Theses and Dissertations

A robust finding in creativity research is that during idea generation, later (vs. earlier) responses on a divergent thinking task tend to be more creative, while the number of responses start off quickly, and then slow down over time, termed the serial order effect. Divergent thinking and time may follow a diminishing returns curve, where there is an optimal amount of time that should be spent while generating ideas. Executive functions (inhibition, updating, and shifting) have been associated with divergent thinking, specifically with the idea generation phase, but the effect of individual differences on the temporal dynamics of divergent thinking …

The Spatial And Temporal Distribution Of Large Rock Blocks And Control On Landscape Evolution In The Ozarks, Chelsea Moran

Graduate Theses and Dissertations

Geologists often use landscape form to infer landscape processes through time. While climate and tectonics shape geomorphic form, the potential range of spatial or temporal scales that can shape any specific landscape can render landscape process-form based hypotheses too general for consideration. Contributions by mathematical modeling have helped bridge the gap between inferring processes from form, notably in how sediment transport dynamics shape hillslopes. However, few models encapsulate the movement of large rock blocks ( >2 meters across) and their potential impact as hillslope sediment transport disruptors. The Upper Buffalo River watershed (BRW) in the Ozarks of northern Arkansas has …

Airbnb Valuation: A Machine Learning Approach, Katherine Wyatt

Graduate Theses and Dissertations

This thesis uses a geospatially-enhanced, machine learning approach to investigate variations in rental success on the peer-to-peer property sharing website Airbnb.com. Geographic factors, listing attributes and amenities, customer response metrics, and host attributes are included in decision tree modeling to predict the short-term probability of receiving a review. The most important variables in increasing model accuracy are assessed and variations in the importance of these variables investigated using Shapley values.

A Generic Qualitative Inquiry Of The Challenges For Black African American Men Who Have Experienced Trauma, Randall Lee Maurice Shakir

Graduate Theses and Dissertations

Black African American Men (BAAM) suffer disproportionately from trauma related challenges and have a higher risk of encountering trauma across the lifespan. The negative impact of trauma is a major public health concern in the United States, evidence suggests trauma negatively impacts the physical well-being, mental health, and mortality rate. BAAM have increased rates of trauma exposure and their traumatic experience is historically complex involving a variety of contemporary issues (i.e. Adverse Childhood Experiences (ACEs), depression, victimization and desensitization, stress). This research aims to explore the complex nature of their trauma-related challenges among a purposeful sample of BAAM participants in …

Testing And Implementation Of Attitude Determination & Control System For Arksat-1 Cubesatellite, Cassandra Sands

Graduate Theses and Dissertations

ARKSAT-1 is a CubeSatellite (CubeSat) developed at the University of Arkansas and launched to the International Space Station on SpaceX mission SPX-27 launching from Kennedy Space Center as part of the NASA’s 8th CubeSat Launch Initiative CSLI-8. ARKSAT-1’s payload features a high-powered LED, the Solid State Inflatable Balloon (SSIB) deorbiting system applicable to small satellites, and a series of InfraRed and Visible cameras. To point the LED or take images of desired observational targets, the spacecraft will need to be able to determine its orientation within its orbit, as well as rotate. This will be achieved through the use of …

Towards Long-Term Fairness In Sequential Decision Making, Yaowei Hu

Graduate Theses and Dissertations

With the development of artificial intelligence, automated decision-making systems are increasingly integrated into various applications, such as hiring, loans, education, recommendation systems, and more. These machine learning algorithms are expected to facilitate faster, more accurate, and impartial decision-making compared to human judgments. Nevertheless, these expectations are not always met in practice due to biased training data, leading to discriminatory outcomes. In contemporary society, countering discrimination has become a consensus among people, leading the EU and the US to enact laws and regulations that prohibit discrimination based on factors such as gender, age, race, and religion. Consequently, addressing algorithmic discrimination has …

Comparative Analysis Of Teacher Effects Parameters In Models Used For Assessing School Effectiveness: Value-Added Models & Persistence, Merlin J. Kamgue

Graduate Theses and Dissertations

Longitudinal measures for students have become increasingly popular to estimate the effects of individual teachers and schools. Value-added models are one of the approaches using longitudinal data to evaluate teachers and schools. In the value-added model (VAM) literature, many statistical approaches have been developed and used to estimate teacher or school effects on student learning. This study opted to use a Bayesian multivariate model for evaluating teacher effects. The generalized persistence models can handle longitudinal data, not vertically scaled, allowing for a below-par teacher’s effects correlation across test administrations. This study first generated longitudinal students’ test score data and used …

Towards Multi-Modal Interpretable Video Understanding, Quang Sang Truong

Graduate Theses and Dissertations

This thesis introduces an innovative approach to video comprehension, which simulates human perceptual mechanisms and establishes a comprehensible and coherent narrative representation of video content. At the core of this approach lies the creation of a Visual-Linguistic (VL) feature for an interpretable video portrayal and an adaptive attention mechanism (AAM) aimed at concentrating solely on principal actors or pertinent objects while modeling their interconnections. Taking cues from the way humans disassemble scenes into visual and non-visual constituents, the proposed VL feature characterizes a scene via three distinct modalities: (i) a global visual environment, providing a broad contextual comprehension of the …

Examining The Relationship Between Student Age And Modality Choice In A Community College’S New Student Orientation Program: A Preregistered Study To Examine The Assumption Of Self-Directed Learning, Amy L. Foree

Graduate Theses and Dissertations

Abstract Understanding and navigating college rules, resources, and expectations is a considerable barrier for students accessing and transitioning to college (Conley, 2007; Williams, 1996; Hooker & Brand, 2010; Ardoin, 2013; Sheppard, 2012). To improve students’ acquisition of pertinent, time-sensitive information, many institutions have implemented mandatory new student orientations (NSO). Orientations provide information such as academic policies and procedures, institutional expectations, campus resources, and financial aid assistance. They also allow students to meet faculty, staff, and other new students. By providing these resources, institutions acclimate students to their new environment. Although colleges realize that new student orientations support students’ success, they …

The Alumni Base Holds The Institution In Their Heart: Alumni Decision Making And Communication Strategies During University Leadership Change, Brandy Cox Jackson

Graduate Theses and Dissertations

The purpose of the research was to understand how alumni executives make decisions and formulate communication strategies during university leadership change. The research was based on the trends found by the American Council on Education that the tenure of the college president has been on the decline since 2006 and is currently 5.9 years. Multiple factors have been identified in the literature that have led to this decline. The research focused on the largest constituency of most universities, its alumni base, and provides context and a description of decision making and communication strategies for alumni executives navigating leadership change. The …

Geospatial Analysis Of Weathering And Recession On Architectural Limestone At The 1891 Powerhouse/Icehouse In Eureka Springs, Arkansas, Stuart Bruce Wright

Graduate Theses and Dissertations

The objective of this study of the architectural limestone of the 1891 Powerhouse/Icehouse in Eureka Springs, Arkansas was to analyze the environmental factors that influenced the deterioration and surface recession of this historical stone structure. The focus of this research was to examine and establish a baseline study that may assist in future monitoring and documentation of this historic limestone structure on stone weathering. A replicable methodology was specifically created toward this baseline research in hopes that it represented a solid baseline study. Observations and data analyses revealed the relationship between the architectural limestone building structure and the dominating recession …

Exploring Success Factors Of Women Senior Leaders In The United States Paper Manufacturing Operations Industry: A Phenomenological Study, Ericka Eggleston

Graduate Theses and Dissertations

The purpose of this study is to understand how women describe their journey to becoming senior leaders within the operations sector of the Paper Manufacturing Industry. This study will provide insights about how women in the male-dominated Paper Manufacturing Industry (PMI) assumed leadership positions. This pre-registered study will offer the framework for this study to be carried out at the University of Arkansas. The researcher will apply a descriptive phenomenological approach that will use semi-structured questions to understand the strategies they used to navigate their career path. Snowball sampling will be used to select 5-15 participants who provide their perceptions …

Tissue-Engineered Models For Investigating Nerve Infiltration In Fibrotic Microenvironments, Nikolas Ala-Kokko

Graduate Theses and Dissertations

Neuron infiltration is involved in a multitude of diseased states and is critical in the regeneration of physiologic conditions. Modeling of innervation in three-dimensional, heterogenous, environments would allow early investigation in the crosstalk of neurons and native cells in normal and pathophysiologic microenvironments to gain an understanding of mechanistic functions. This would allow for greater insight into the role of metabolism, cell adhesion, microenvironmental alternations, cellular crosstalk, and signaling pathways that play a role in the promotion and prevention of neurite growth. In this thesis, with the construction of collagen-based hydrogels as the foundation for cell culture, we investigate cell …

Health Beneficial Effects Of Black Raspberry, Blueberry, And Blackberry Volatile Extracts In Lung And Colon, Inah Gu

Graduate Theses and Dissertations

Berries are one of the most consumed fruits in our diet, and rich in dietary fiber, vitamins, minerals, polyphenols, and volatiles. Volatiles are responsible for the aroma of berries, and are widely used in food, perfumery, and cosmetic industries. However, the potential health beneficial effects of berry volatiles have not been extensively studied. Recently, we found that berry volatiles from cranberries, black and red raspberries, strawberries, blueberries, and blackberries have an anti-inflammatory effect on inflamed murine macrophage cells. Since inflammation can develop into many chronic diseases, and berry volatiles can be inhaled or consumed and pass through the lungs or …