Digital Commons Network^™

Hobby Grade Lithium-Ion Batteries For Spacecraft Applications: Establishing An Automated Electrical Characteristics Testing Procedure For Flight Acceptance Of Non-Space-Grade Small Secondary Batteries, Braidon Hughes

Graduate Theses and Dissertations

Li-ion batteries are widely used due to the large amount of rechargeable energy they pack into a small, light package. This higher energy density makes Li-ion batteries ideal for small satellite applications, specifically CubeSats. CubeSats have grown in popularity in higher level education due to the National Aeronautics and Space Administration’s implementation of the Cube Satellite Launch Initiative, making it easier and cheaper to conduct small, low orbit missions. Because these CubeSats are occupying the same space as a crewed spacecraft, it is imperative that they are safe. There are numerous reports of Li-ion batteries creating fires that result in …

Audience, Minah Kim

Graduate Theses and Dissertations

My work, “audience,” reflects binary oppressions sensed and recognized in my private memory and psychological space of living as a transnational being. Linguistic and sensical cognition I(a vulnerable transnational individual) had, have easily been dis-esteemed and devalued by White-centric epistemology. By confronting the reality of history that shapes my thoughts, performance, names, and meanings, I emphasize transnationality as an opportunity to multiply visual tools, dialogues, and inter-connections of individuals. This work integrates moments of physical connection and accountability by utilizing multidisciplinary expression, including ceramics, writing, sound, and the movements of performers and of the audience. Like an interfusion between artists …

Additive Manufacturing Of Soil Using Bio-Cementation, Christina Childress

Graduate Theses and Dissertations

Microbially Induced Calcite Precipitation (MICP) is an emerging soil treatment technique that is proven to increase strength, decrease erosion, reduce liquefaction risk, enhance slope stability, decrease compressibility, decrease swelling potential, and overall create a more competent soil. The benefits and applications of MICP are broad, and this research seeks to broaden them further by developing a single-phase additive manufacturing application with no treatment time delay. This is done by analyzing layering behaviors of five USCS soil classifications (100 % Ottawa sand, sand clay mixtures, and 100% lean clay) which provides insight into process variables such as the solution volume and …

Deep Learning Strategies For Pool Boiling Heat Flux Prediction Using Image Sequences, Connor Heo

Graduate Theses and Dissertations

The understanding of bubble dynamics during boiling is critical to the design of advanced heater surfaces to improve the boiling heat transfer. The stochastic bubble nucleation, growth, and coalescence processes have made it challenging to obtain mechanistic models that can predict boiling heat flux based on the bubble dynamics. Traditional boiling image analysis relies on the extraction of the dominant physical quantities from the images and is thus limited to the existing knowledge of these quantities. Recently, machine-learning-aided analysis has shown success in boiling crisis detection, heat flux prediction, real-time image analysis, etc., whereas most of the existing studies are …

An Investigation Of The Flexural Strength And Toughness Of Hybrid Plain And Fiber Reinforced Concrete For Pavement Applications, Wesley Keys

Graduate Theses and Dissertations

For decades, many solutions have been evaluated to combat cracking in concrete pavements. The study presented in this paper evaluates and compares the flexural performance under a third point loading configuration of plain concrete (PC) beams, fully fiber reinforced concrete (FRC) beams, and hybrid PC and FRC beams, with a top PC and bottom FRC layer. The purpose of this hybrid approach was to provide FRC in only half the section, saving cost, while providing a PC surface layer that is easier to finish. All PC top layers were applied at an age of 7-days, considered a reasonable time for …

Retrospective Analysis Of Impacts Of Highway Bypass And Widening Projects, Sanjeev Bhurtyal

Graduate Theses and Dissertations

Community members often worry that highway projects may have negative impacts on their local economies. This is typical for highway bypass and widening projects in small cities (population less than 50,000). It is a challenge for planners to balance public concerns of economic decline with desired project outcomes of mobility and safety. Much of this challenge stems from a lack of information on post-project outcomes related to economic and safety impacts of new construction projects. Thus, there is a need for an evidence-based framework to help planners with the decision-making process and better inform the community on potential outcomes. This …

Shear Strength Of Concrete Beams Made With Belitic Calcium Sulfoaluminate Cement, Caleb W. Chesnut

Graduate Theses and Dissertations

The need for a cleaner alternative to portland cement (PC) concrete has led to increasing interest in alternatives to PC. Structural properties of most of these alternative cements are still an open research topic. One promising alternative cement is belitic calcium sulfoaluminate (BCSA) cement. The study presented in this paper investigated the shear strength, long term compressive strength, and carbonation in BCSA cement and PC concrete beams. A total of twelve eight-foot long beams were made; eight BCSA cement concrete beams and four PC concrete beams to be tested at various ages depending on cement type. Two beams of each …

How Are Agricultural Research Projects Conceiving Innovation? An Assessment Of The European Union Multi-Actor Projects, Samuel Brea Martinez-Collado

Graduate Theses and Dissertations

Horizon research programs are the European Union’s lighthouse for innovation and research concerning the agri-food chain, the management of natural resources, and the bioeconomy. Their innovation strategy approach is one that pursues the practical application of the research via the collaboration of all actors involved. Such strategy is the reflection of a Multi-Actor Approach as their procedure to enhance innovation. This paper presents the main trends and directions 101 Multi-Actor Projects (MAPs) are following on said approach towards innovation. The analysis is based on the use of well-defined “pathways” and “measures” proposed in the Guidelines for Evaluation of Innovation in …

Dissonance Between Christian Beliefs And Eating Habits In The South, Karli Dianne Stringer

Graduate Theses and Dissertations

The purpose of this qualitative study was to initiate understanding of how obesity in the South is still so prevalent even though the majority of inhabitants subscribe to a faith that discourages unhealthy lifestyles. Furthermore, the information presented in this research sought to fill the knowledge gap for communicators and educators concerning the dissonance between Christianity in the South and the unhealthy eating habits of Southerners. Grounded in the Cognitive Dissonance Theory, this study comprised of a semi-structured interview route in which Protestant evangelical Christians in the South (N = 11) participated in a descriptive study conducted by a committee …

Respiratory Compensated Robot For Liver Cancer Treatment: Design, Fabrication, And Benchtop Characterization, Mishek Jair Musa

Graduate Theses and Dissertations

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death in the world. Radiofrequency ablation (RFA) is an effective method for treating tumors less than 5 cm. However, manually placing the RFA needle at the site of the tumor is challenging due to the complicated respiratory induced motion of the liver. This paper presents the design, fabrication, and benchtop characterization of a patient mounted, respiratory compensated robotic needle insertion platform to perform percutaneous needle interventions. The robotic platform consists of a 4-DoF dual-stage cartesian platform used to control the pose of a 1-DoF needle insertion module. The active …

Factors Influencing The Usage Of Shared E-Scooters : A Case Study Of Chicago, Farzana Mehzabin Tuli

Graduate Theses and Dissertations

The rapid popularity growth of shared e-scooters creates the necessity of understanding the determinants of shared e-scooter usage. This thesis estimates the impacts of temporal variables (weather data, weekday/weekend, and gasoline prices) and time-invariant variables (socio-demographic, built environment, and neighborhood characteristics) on the shared e-scooter demand by using four months (June 2019- October 2019) period of data from the shared e-scooter pilot program in Chicago. The study employs a random-effects negative binomial (RENB) model that effectively models shared e-scooter trip origin and destination count data with over-dispersion while capturing serial autocorrelation in the data. Results of temporal variables indicate that …

Automated Report Based System To Encourage A Greener Commute To Campus, Ronald Velasquez

Computer Science and Computer Engineering Undergraduate Honors Theses

This project consists of the design and implementation of a tool to encourage greener commutes to the University of Arkansas. Trends in commuting of the last few years show a decline in not so environment-friendly commute modes. Nevertheless, ensuring that this trend continues is vital to assure a significant impact. The created tool is an automated report system. The report displays information about different commute options. A Google form allows users to submit report requests, and a web app allows the sustainability office to process them in batches. This system was built in the Apps Script platform. It implements several …

The Effects Of Commercial Harvest On The Density And Demography Of Aquatic Turtles In Arkansas, Andrhea Darleen Massey

Graduate Theses and Dissertations

The United States is home to the second highest concentration of turtle species in the world, after Asia. As of 2018, there are 57 turtle species recognized within the US, 40% of which are listed as threatened or endangered, with the primary threats to population persistence identified as over-consumption and/or habitat loss. Within the US, the Mississippi Alluvial Valley (MAV) region represents the second highest turtle species richness, after the Mobile River Basin. The MAV region of Arkansas is one of the least regulated in terms of commercial aquatic turtle harvest and has undergone large-scale habitat conversion from bottomland hardwood …

Machine Learning Applied To A Modern-Pleistocene Petrographic Dataset: The Global Prediction Of Sand Mineralogy (Gloprsm) Model, Isaac Johnson

Graduate Theses and Dissertations

Petrography has long been used as a tool to decipher the sedimentary provenance of sand and sandstone from the relative proportions of framework grain types. Petrographers have also related the proportions of quartz (Q), feldspar (F), and lithic (L) grains to the processes that form and modify sediments within sediment routing systems. This past work has shown that factors including source lithology, climate, transport history, and tectonism work in concert to modify the framework mineralogy of sand. However, there is a lack of a quantitative understanding of the interactions and feedbacks between these factors and how they modify sand mineralogy. …

Canine Microwear In Relation To Diet In Sumatran Primates And African Great Apes, Putu Pujiantari

Graduate Theses and Dissertations

This thesis considers canine microwear in relation to diet in five Sumatran primates (Pongo abelii, Hylobates lar, Hylobates agilis, Presbytis thomasi, and Macaca fascicularis) and two African great apes (Pan paniscus and Pan troglodytes schweinfurthii) using both microwear texture analysis and microwear feature analysis techniques. Statistical results for texture analysis show that there are significant differences in scale of maximum and heterogeneity. This indicates that some species have large pits on their canine surfaces, having these dominated by deep features at coarse scale yet have a slight microwear heterogeneity. For feature analysis, all variables show statistically significant variation. Variance in …

Alone Together: The Experiences Of Lgbtqia+ Undergraduates At Faith-Based Colleges, Jennifer Edwards

Graduate Theses and Dissertations

This qualitative study aimed to explore the experiences of LGBTQIA+ alumnix who attended faith-based colleges. The study was guided by Strayhorn’s (2019) College Students’ Sense of Belonging Theory and Abes’ et al. (2007) Reconceptualized model of multiple dimensions of identity. The scope of experiences explored was narrowed to three of the five categories in Schreiner’s (2010a) Thriving Quotient. These categories were: positive perspective (outlook on life), social connectedness, and diverse citizenship.

The study included 11 participants from 7 faith-based colleges and represented various intersections of sexual and gender identity. The study employed constructivist grounded theory methodology, an inductive research approach …

Nutrient Uptake And Management Strategies In Recirculating Hydroponic Systems, Lauren Leigh Houston

Graduate Theses and Dissertations

Nutrient management in recirculating hydroponic systems requires the periodic replenishment of water and nutrients to the nutrient solution reservoir. Common nutrient management strategies, such as replenishing the reservoir with fresh solution and maintaining a constant solution electrical conductivity (EC), can lead to ion accumulation and nutrient imbalances since nutrients are taken up by roots and depleted from solution at different rates. To avoid nutritional disorders, commercial growers typically dump and replace the hydroponic solution periodically, which is wasteful and has an economic cost. A potential alternative is to specially formulate the nutrient replenishment solution to balance the supply of nutrients …

Crispr Gene Editing Drivers, Barriers And Prospects: A Comparative Study Among Plant Scientists Globally, Adriaan Johannes De Lange

Graduate Theses and Dissertations

The introduction of CRISPR gene editing into food crops has potential to contribute to food security and sustainable food production globally. To date, most scientific studies have focused on consumer perception of CRISPR gene edited foods or the potential benefits and risks of the CRISPR technology and none have focused on the perceptions of plant scientists concerning CRISPR gene editing. This study aimed to explore the investments, functions, barriers, benefits for specific crops and beneficiaries of CRISPR gene editing according to plant scientists, by distributing an online survey in which 1,040 plant scientists active across six continents and in both …

An Assessment Of The Neurovascular Structures Of The Trigeminal Nerve And Their Relationship To Diet In Primates, Caitlin Yoakum

Graduate Theses and Dissertations

The inferior alveolar nerve (IAN) enters the mandible via the mental foramen, supplies nervous sensation to the mandibular teeth as it travels through the mandibular canal, and exits the mandibular foramen to send information to the brain to maintain chewing cycles and protect the teeth from damage. Although bony canals and foramina have been shown to form around soft-tissue structures, there are some examples (e.g., the hypoglossal nerve/canal) where the nervous structures do not comprise most of the canal/foramina space. It is important to know the size of nerves because it has been established that larger nerves convey more information …

Thermometry Via Diffusion In Ferrous Core-Shell Nanoparticles For Induction Heating Applications, Hayden Carlton

Graduate Theses and Dissertations

Induction heating causes the release of enormous amounts of heat from dispersed magnetic nanoparticles. While the rate of heat transfer can be easily quantified calorimetrically, measuring the temperature of the nanoparticles on the nanoscale presents experimental challenges. Fully characterizing the temperature and thermal output of these magnetic particles is necessary to gauge overall heating efficiency and to provide a more holistic understanding of heat transfer on the nanoscale. Herein, this dissertation seeks to develop a novel nanoparticle thermometry technique, which correlates diffusion behavior in core-shell nanoparticles to local temperature. Initial measurements suggested that heating silica capped ferrous nanoparticles (SCNPs) via …

Nonmetallic Jet Impingement Thermal Management For Power Electronics Via Additive Manufacturing, Reece Whitt

Graduate Theses and Dissertations

The increase in energy demanded by transportation and energy sectors has necessitated highly efficient thermal management for reliable power electronics operations. Conventional cooling techniques are limited by their inability to target switching location hot spot temperatures, leading to non-uniform thermal gradients. These devices, such as cold plates and heat sinks, also utilize heavy metallic structures that can accentuate electromagnetic interferences generated by high voltage switching processes. This work proposes a non-metallic jet impingement cooler for more customized thermal management, while simultaneously reducing the harmful effects of electromagnetic interferences. Additive manufacturing is utilized to enable jet impingement zones to target individual …

Combined Stressors In Reliability Failure Modes In Flip-Chip Electronic Packaging, Mahsa Montazeri

Graduate Theses and Dissertations

The trend toward miniaturization of electronic devices to fulfill Moore’s law introduces new reliability concerns to the electronic packaging process while worsening existing primary challenges. In solder interconnect specifically, temperature cycling is one of the prominent failure threats. However, with further downscaling of the flip-chip solder connections, electromigration also present a precarious failure mode in these interconnects. On the other hand, understanding the degradation mechanism in solders is crucial for the power electronic products' reliability considering the industrial tendency to replace wirebonds with solder attachment while improving the current carry capacity. This dissertation utilizes FEA simulation and an experimental approach …

Mission Profile Effects On Automotive Drivetrain Electronics Reliability: Modeling And Mitigation, Bakhtiyar Mohammad Nafis

Graduate Theses and Dissertations

The reliability of electronic devices is dependent upon the conditions to which they are subject. Temperature variations coupled with differences in thermal expansion between bonded materials results in thermomechanical stresses to build up, which can instigate failure in the interconnects or other critical regions. With the move towards electrification in the automotive industry, there is the increasingly important consideration of powertrain electronics reliability, the pertinent conditions being governed by the drive cycle or mission profile of the vehicle. The mission profile determines the power dissipated by the electronic devices, which determines the peak and mean temperature, temperature swing and the …

Economic Potash Fertilizer Rate Recommendations, Kimberly B. Oliver

Graduate Theses and Dissertations

This thesis is comprised of two studies that estimate profit-maximizing potassium (K) fertilizer application rates for various crops across different time periods. Estimation of profit-maximizing fertilizer-K rate (K*) for both studies considered the initial soil test level of K (STK) and yield response information, as traditional recommendations do, and added crop price and the cost of fertilizer. Profit maximum occurs where the marginal revenue from additional yield is equal to the marginal cost of applying an additional unit of fertilizer-K. The first study calculated K* for corn (Zea mays) and cotton (Gossypium hirsutum) and compared results to previous studies on …

Teacher And Staff Perception Of School Climate: A Case Study, Michael Shane Hampton

Graduate Theses and Dissertations

The purpose of this study is to determine how different public-school teachers and staff perceive school climate at an achieving public middle school. The research sought to find relationships between teacher sub-groups and other staff members, and how they perceived the school climate, either negatively or positively. The researcher believed that there would be a positive perception of school climate, which coincided with high student achievement. Additionally, it was believed that there would be no relationship between teacher types or demographics, and how the climate would be perceived among the different groups. This paper also presents a review of the …

Deciphering Chemomechanical Couplings In Proteins Using Microsecond-Level Molecular Dynamics Simulations, Vivek Govind Kumar

Graduate Theses and Dissertations

All-atom molecular dynamics (MD) simulations combine the high temporal resolution of experimental methods like smFRET and spatial resolution of methods like x-ray crystallography, to provide a detailed dynamic picture of biomolecular processes. Here, microsecond-level atomistic MD simulations have been used to characterize chemomechanical couplings in human fibroblast growth factor 1 (hFGF1) and the spike proteins of SARS CoV-1 and SARS-CoV-2. hFGF1 is a globular signaling protein that is involved in several physiological processes ranging from cell proliferation to wound healing. Experimental studies have previously described the low proteolytic and thermal stability of hFGF1, in addition to the stabilizing role of …

Covid-19 Masks In Terms Of Functional, Expressive, And Aesthetic Consumer Needs, Lily Highley

Apparel Merchandising and Product Development Undergraduate Honors Theses

The purpose of this study was to assess consumers' perspectives of COVID-19 masks under the functional, expressive, and aesthetic areas. Due to the COVID-19 pandemic, masks have become an “accessory” to everyday life, and it was essential to research masks under these unique areas and explore consumer perceptions.

This study took place after background research on the topic and the FEA model. The study included a survey sent to Bumpers College students upon approval from the IRB. The data was analyzed and interpreted specifically in the FEA areas and can be useful to better understand the students at the University …

Applying Artificial Intelligence In The Hotel Industry: Exploring Perspectives Of Employees, Logan O'Hara

Human Nutrition and Hospitality Management Undergraduate Honors Theses

Robots, Artificial Intelligence, and Service Automation, or RAISA, has become increasingly accessible and affordable for a wider demographic of businesses, including hospitality operations, to implement over the last couple of decades. Especially over the past five years, we’ve seen a significant surge of interest in automating within the service industry and a coupled sense of uneasiness that this technological development would in turn displace the human workers, due to factors such as cost of labor and perceived removal of human error; however, this thesis will posit that automation is most effectively used by augmenting the capabilities of the present workforce. …

Preliminary Development Of The Dialysis-Membrane-Based Passive Biocide Delivery System For Spacecraft Water Recovery Units, Rogelio Elias Garcia Fernandez

Graduate Theses and Dissertations

The purpose of this investigation is to explore the capabilities of a dialysis-membrane-based system for the in-line dosing of silver ions to treated water in spacecraft water recovery units. The spacecraft environmental control and life support system community (ECLSS) are interested in adopting silver ions as a biocide in future spacecraft water recovery processes since silver ions are effective biocide at concentrations that humans can safely consume. The system has been designed following the configuration of the Water Processor Assembly (WPA) aboard the International Space Station. In this configuration, silver ions have to be added at the last step in …

Pets And Problems: Exploring Community Patterns In Calls For Animal Services, Paige Dejarnett

Sociology and Criminology Undergraduate Honors Theses

Pets have historically been viewed as family members, children, property, or economic resources. However, research surrounding animal maltreatment has expressed this issue as an individually-based problem, rather than a community-based phenomenon. Correlations have been found between animal cruelty, antisocial behaviors, and future interpersonal violence, whether this correlation be a predictive relationship, or a resultant relationship. Past research has also found correlations between animal treatment practices and the rural/urban differences of this behavior. However, there are many community-based indicators that have not been explored to understand the distribution of animal maltreatment. This study aims to explore these ideas by analyzing the …