Digital Commons Network^™

Halide Substitution Of Ternary Bismuth Chalcogenides For Photovoltaic Applications, Thomas Boggess

Theses and Dissertations

Semiconductors play an integral part in modern society. From computing to LEDs their use is ubiquitous, and no field is more reliant on them than that of power generation. Current political movements have seen a push to decrease reliance on traditional forms of power generation, which relies on fossil fuels, to renewable sources such as solar power. However, current commercial solar panels, based on silicon, are lacking in efficiency, only reaching between 18% and 22% efficiency.¹ In recent years, materials called perovskites have been garnering significant attention as possible replacements for silicon cells due to their favorable optoelectronic properties. …

Role Of Fungal Arv-1 Protein In Sterol Metabolism And Pathogenicity Of The Chestnut Blight Fungus Cryphonectria Parasitica, Soumyadip Kundu

Theses and Dissertations

Intracellular sterol redistribution is an important step in the lipid homeostasis of organisms, a process directly linked to the organizational arrangement in the plasma membrane (PM) of cells. Previous studies in the budding yeast Saccharomyces cerevisiae have demonstrated that the ARV1 (ACAT-related enzyme-2 required for viability 1) protein is a major regulator of sterol transport from the endoplasmic reticulum to the plasma membrane, contributing to the structural organization of the PM, rendering it resistant to anti-fungal compounds as well as maintaining ER integrity. This study assessed the significance of ARV1 in the plant pathogenic fungus Cryphonectria parasitica (Cparv1) …

An Investigation Into Perceptions, Expectations, And Development Of Professional Skills In Engineering Students, Morgan Kathryn Green

Theses and Dissertations

Upon graduation from an undergraduate institution, engineering graduates are expected to have a baselevel skill in technical skills related to their discipline. Teaching technical skills comes naturally to engineering programs as the conceptual understanding of the material form the foundation of engineering ability. However, engineering graduates also are expected to have a baselevel of professional skills, which are more subjective in nature and do not have a standardized approach for teaching or assessing them at the undergraduate level. An investigation into current perceptions of professional skills by relevant parties is an initial step in providing more structure to professional skills …

Monolithic Multiphysics Simulation Of Hypersonic Aerothermoelasticity Using A Hybridized Discontinuous Galerkin Method, William Paul England

Theses and Dissertations

This work presents implementation of a hybridized discontinuous Galerkin (DG) method for robust simulation of the hypersonic aerothermoelastic multiphysics system. Simulation of hypersonic vehicles requires accurate resolution of complex multiphysics interactions including the effects of high-speed turbulent flow, extreme heating, and vehicle deformation due to considerable pressure loads and thermal stresses. However, the state-of-the-art procedures for hypersonic aerothermoelasticity are comprised of low-fidelity approaches and partitioned coupling schemes. These approaches preclude robust design and analysis of hypersonic vehicles for a number of reasons. First, low-fidelity approaches limit their application to simple geometries and lack the ability to capture small scale flow …

Variational And Adaptive Non-Local Image Denoising Using Edge Detection And K − Means Clustering, Shiraz Mujahid

Theses and Dissertations

With the increased presence of image-based data in modern applications, the need for robust methods of image denoising grows greater. The work presented herein considers two of the most ubiquitous approaches towards image denoising: variational and non-local methods. The effectiveness of these methods is assessed using quantitatively using peak signal-to-noise ratio and structural similarity index measure metrics. This study employs ��−means clustering, an unsupervised machine learning algorithm, to isolate the most dominant cluster centroids within the incoming data and propose the introduction of a new adaptive parameter into the non-local means framework. Motivated by the fact that a majority of …

Comet Nuclei Activity Simulation Using Percolation Theory On Comet 67p/Churyumov– Gerasimenko, Ahmad Sohani

Theses and Dissertations

Comets, remnants of the solar system's formation, exhibits partially unexplained outbursts that are closely tied to the physical structure of the nucleus. To investigate outbursts, we employed pore network modeling techniques, such as the Bower-Watson algorithm and Voronoi diagrams, to better represent the nucleus' complex porous structure and simulate gas transfer processes. We examined heat diffusion in the comet's subsurface and its influence on crystallization. The extra heat generated by crystallization can shift the crystalline front deeper into the nucleus, accelerating subsurface evaporation rates. This process results in the formation of a thicker ice mantle with reduced porosity on the …

Where Did They Come From? Why Did They Go? How Engineering Students’ Perceptions Cultivate Experiences And Influence Behaviors, Sara Campbell Vick

Theses and Dissertations

Engineering undergraduate students have opinions and perceptions of engineering disciplines and engineering undergraduate students do not always matriculate and graduate in precisely the same discipline. Understanding how these two characteristics of engineering undergraduate students interact to inform behaviors is important for engineering educators and administrators to increase and improve recruitment and retention among their students.

This dissertation approached each characteristic of engineering students, first separately and then together. A nationwide survey of undergraduate engineering students found significant differences in how students perceive various engineering disciplines along several paired-term anchored scales. These differences were equally significant when scores were considered in …

Development And Evaluation Of An Automated Tactical Tillage Tool To Control Weeds In Row-Crop Production Systems, Grace Mccormick Friday

Theses and Dissertations

Weed control is an integral part of a successful overall production strategy in row- cropping systems and has the potential to reduce or eliminate yield losses that negatively affect profitability. Timely and correctly selected herbicide applications are the major keys for effective weed control in a majority of instances. However, there are negative factors that contribute to ineffectiveness and weed escape issues that currently lack viable options for management. Sparsely populated late-season weeds that emerge after lay-by herbicide applications and weeds that have become tolerant and resistant to traditional herbicide chemistries are of greatest concern. Historically, these weeds would have …

Interactive Effects Of Bark Beetles, Ophiostomatoid Fungi, And Subterranean Termites On Wood Decomposition And The Biogeochemical Cycling Of Pine Forests, Kimberlyn Pace

Theses and Dissertations

A frequent source of pine tree mortality in recent years can be attributed to pine bark beetles and their vectored Ophiostomatoid fungi, an organism that has been observed to attract subterranean termites that preferentially recruit to this downed woody debris. This interaction may significantly modify biogeochemical fluxes in bark beetle mass mortality events, but studies are often limited to singular regions or single pine-dominated ecosystems. Two studies were designed to test the interactive effects of these associations on terrestrial biogeochemical cycles and decomposition processes, the first using replicated field trials in Mississippi, Arizona, and Honduras across two years and the …

Robotic Cotton Harvesting With A Multi-Finger End-Effector: Research, Design, Development, Testing, And Evaluation, Hussein Gharakhani

Theses and Dissertations

Cotton is harvested with large and heavy machines that are very efficient but have some disadvantages. They can harvest the crop only once at the end of the growing season. Since cotton bolls do not mature uniformly, the early opened bolls expose their fiber to weather for extended periods, reducing lint quality. In addition, the machines can also compact the soil, reducing water and fertilizer usage efficiencies and crop yields in the following years. Robotic cotton harvesting offers a promising solution to these issues. Smaller robotic harvesters could go to the field multiple times during the season to pick cotton …

Determining The Impact Of Post-Harvest Water Management On Chironomid Abundance, Agrochemical Biomass And Potential Trophic Biomagnification, Mason Thomas

Theses and Dissertations

Agriculture has diminished shorebirds’ natural habitat in the Mississippi Alluvial Valley. Remaining natural stopover sites are supplemented with agricultural fields during the fall and winter. This study evaluates the impact of 4 different post-harvest water management strategies on shorebird food abundance and potential agrochemical biomagnification. Chironomid samples estimated abundance, biomass, and chironomid agrochemical concentration in each field. A risk assessment of agrochemical biomagnification to shorebirds was made across all treatments. Of treatments represented on all study sites, winter treatment had greatest chironomid abundance and biomass. Models indicated that days since flood initiation, start date, and temperature are significant predictors of …

Activity Level Of Helicoverpa Armigera Nucleopolyhedrovirus (Hearnpv) And Feeding Habits Of Helicoverpa Zea Larvae After Ingestion Of Hearnpv In Mississippi Soybean, Judge Tyler Fortenberry

Theses and Dissertations

HearNPV was applied to a soybean field and evaluated for residual efficacy at different time intervals (0, 12, 24, 36, 48, and 72 hours) after application in laboratory bioassays with treated leaves. Larval mortality was rated at five, seven and twelve days after larval infestation. Larval mortality increased as the number of days after infestation increased. To evaluate the feeding habits of Helicoverpa zea at the 2^nd and 3^rd instar, HearNPV exposed larvae and untreated larvae were weighed at zero (before diet exposure), four, and seven days. At four days after exposure, larval weight gain of …

Characterizing Quinclorac-Resistant Smooth Crabgrass (Digitaria Ischaemum) Control And Possible Metabolic Mechanisms Of Resistance, Atikah Dwi Putri

Theses and Dissertations

Quinclorac controls crabgrass (Digitaria spp.) post-emergence in cool- and warm-season turfgrass. A rate response study revealed that two Mississippi smooth crabgrass (Digitaria ischaemum) species (MSU1 and MSU2) are resistant to quinclorac. Following that, field experiments were carried out to evaluate programmatic approaches to control one of these populations. Despite prior study on quinclorac-resistant weeds, to date, quinclorac-resistant smooth crabgrass and its mechanism of resistance have only been reported once in California. The mechanism of resistance of MSU1 and MSU2 relative to susceptible (SMT) was then investigated. The SMT biotype accumulated three times more cyanide than the resistant …

The Impact Of Environmental Education Delivery Methods And Outreach Messaging On Attitudes, Interests, And Intended-Behavior Changes Toward Nature, Vanessa Elizabeth Hoffman

Theses and Dissertations

Environmental education (EE) is important for environmental awareness and stewardship. Involving youth and adults in EE ensures current and future generations will conserve natural resources. This thesis explores impacts of delivery methods on participants’ environmental attitudes and behaviors toward nature through middle school classroom- and camp-based EE instruction, focus group interviews with rural minority youth, and adult responses to aquatic conservation outreach messaging. I observed no difference in environmental attitudes between online versus in-person delivery of EE lessons for middle-schoolers. Outdoor-based learning may be more impactful for EE than experiential, classroom-based learning. Focus group outcomes suggested youth EE programs should …

Beyond Algorithms: A User-Centered Evaluation Of A Feature Recommender System In Requirements Engineering, Oluwatobi Lasisi

Theses and Dissertations

Several studies have applied recommender technologies to support requirements engineering activities. As in other application areas of recommender systems (RS), many studies have focused on the algorithms’ prediction accuracy, while there have been limited discussions around users’ interactions with the systems. Since recommender systems are designed to aid users in information retrieval, they should be assessed not just as recommendation algorithms but also from the users’ perspective. In contrast to accuracy measures, user-related issues can only be effectively investigated via empirical studies involving real users. Furthermore, researchers are becoming increasingly aware that the effectiveness of the systems goes beyond recommendation …

Navigating The Road To Distributional Social Equity Using Smart Cities Technologies, Annus Azhar

Theses and Dissertations

This dissertation aims to understand the mechanisms behind the adoption of smart cities technologies (SCT) and how they can promote social equity in local communities in the United States. There is a distinct lack of empirical research addressing the methods designed for the promotion of social equity despite their numerous benefits. The present study will address this omission in the scholarship by providing evidence-based insights on how public administrators can leverage SCT to promote distributional social equity through the Digital Era Governance (DEG) and Adoption Theory frameworks. This study also demonstrates the efficacy of applying the Technology Acceptance Model (TAM) …

Quantifying Seasonal And Annual Precipitation Variability On San Salvador Island, Bahamas Using Surface Observations And Satellite Estimates., John Bryson Wells

Theses and Dissertations

San Salvador Island is a small Bahamian island located in the subtropics just north of the Tropic of Cancer. Due to its subtropical location, the island is influenced by both mid-latitude and tropical weather patterns. These weather patterns vary in scale from localized convective uplift to synoptic-scale systems. This study compares satellite-derived estimates of precipitation and rain gauge observations from June 2019 through September 2021 to evaluate the relationship between the two datasets. This study then uses the satellite-derived estimates of precipitation over a 20-year period to quantify annual and seasonal variability in precipitation on San Salvador. Corroborating past research, …

Mitigating Adverse Impacts Of Increased Electric Vehicle Charging On Distribution Transformers, Akansha Jain

Theses and Dissertations

There is a growing interest in electric transportation, and the number of electric vehicles (EVs) is increasing. The resulting increase in EV charging power demand has an adverse impact on the existing power grids, especially the distribution transformers. The repeated and continued overloading caused by EV charging can significantly reduce their operational life. This dissertation aims to comprehensively study the adverse impacts of EV charging on distribution transformers and provide robust and practical solutions to mitigate it. A typical North American secondary distribution system with different EV penetration levels and four realistic residential EV charging scenarios are used for the …

Physiological And Proteomic Analysis Of Soybean In Response To Drought And Heat Stress, Amandeep Kaur

Theses and Dissertations

Drought and temperature stress are the two most important factors limiting crop productivity. A physiological and proteomic analysis of soybean was performed to investigate the negative impact of these variables. The previous studies reported the beneficial effect of silicon under stress conditions. Silicon supplementation may promote plant growth under drought stress, although the mechanism to alleviate drought stress is uncertain. The proteomic analysis of chloroplast proteins was carried out to study the response of silicon supplementation under drought stress.

Similarly, temperature stress, mainly heat stress, has an adverse effect on soybean plants. The comparative analysis of two soybean cultivars, DS25-1 …

The Consequences Of Low Energy Availability Related To Relative Energy Deficiency In Male Athletes: A Systematic Review, Lauryn Bailey

Theses and Dissertations

RED-S is a syndrome that stems from low energy availability (LEA) in athletes. It can impact numerous physiological and psychological functions, as well as negatively affect performance. Because RED-S is a relatively new syndrome, there are few studies showing the impact of RED-S on performance and physiological factors. The aim of this systematic review was to examine the consequences of induced LEA in relation to RED-S in male athletes. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, Five studies were deemed eligible based on inclusion and exclusion criteria. Studies measured risk of RED-S through body composition, bone …

A Step Toward Understanding Software Development In The Public Sector: A Study Of A Department Of Defense Research And Development Organization, Joshua Q. Church

Theses and Dissertations

This paper focuses on the importance of effective software development processes and a foundational understanding of success factors in the public sector. Although there has been significant investment in information technology, not all public sector software projects result in a successful return on investment. This study explores the crucial factors, referred to as Critical Success Factors (CSFs), that enable the success of public sector software development projects. Additionally, this study aims to discover if the CSFs, the Software Development Life Cycle (SDLC), or its methodologies are more impactful for the success of software projects. This study aims to also identify …

Development Of Live Attenuated A. Hydrophila Vaccines And Understanding Of Macrophage-Aeromonas Hydrophila Interactions, Eda Ozdemir

Theses and Dissertations

Channel catfish farming is the largest aquaculture industry in the U.S., and virulent Aeromonas hydrophila is an important re-emerging bacterial pathogen of farmed catfish. A. hydrophila is ubiquitous in the aquatic environment and causes motile Aeromonas septicemia (MAS) in farmed catfish. A. hydrophila infection is challenging to treat due to rapidly progressive mass mortalities. Although florfenicol has been used in managing outbreaks, acute onset of anorexia, drug cost, and emergence of antimicrobial-resistant strains are significant concerns. Prevention of MAS by vaccination could be a promising approach, but a commercial vaccine is not available. Thus, it is critical to develop effective …

Design Of High-Power Ultra-High-Speed Permanent Magnet Machine, Md Khurshedul Islam

Theses and Dissertations

The demand for ultra-high-speed machines (UHSM) is rapidly growing in high-tech industries due to their attractive features. A-mechanically-based-antenna (AMEBA) system is another emerging application of UHSM. It enables portable wireless communication in the radio frequency (RF)-denied environment, which was not possible until recently. The AMEBA system requires a high-power (HP) UHSM for its effective communication performance. However, at the expected rotational speed range of 0.5 to 1 million rpm, the power level of UHSM is limited, and no research effort has succeeded to improve the power level of UHSM.

The design of HP-UHSM is highly iterative, and …

Hydrological And Water Quality Assessment Of Forested Coastal Watersheds, Shreeya Bhattarai

Theses and Dissertations

Coastal regions are at risk of environmental threats. Flooding in coastal rivers is the result of intense precipitation which is triggered by climate change. Coastal watersheds are prone to losing significant amounts of sediment and nutrients because of the shorter transport pathway that drains directly into the coastal water. In this study, the hydrology, flood frequency, and water quality assessment of two coastal watersheds, Wolf River watershed (WRW) and Jourdan River watershed (JRW), were conducted using the Soil and Water Assessment Tool (SWAT). Since WRW and JRW are the main tributaries to fetch freshwater to Saint Louis Bay (SLB) of …

Evaluation Of Italian Ryegrass And Palmer Amaranth Control In Mississippi, Johnson Harris Hughes

Theses and Dissertations

Italian ryegrass is a problematic weed in Mississippi corn production due to the development and proliferation of glyphosate resistance. Studies were conducted to assess Italian ryegrass control prior to planting using herbicides. Effects of fall and spring applied burndown herbicide applications for Italian ryegrass control and subsequent corn grain yield were investigated at the R.R. Foil PSRC in Starkville, MS, at the Coastal Plain Experiment Station in Newton, MS, and the Black Belt Experiment Station in Brooksville, MS on soil textures ranging from sandy loam to silt clay loam. A fall preemergence (PRE) application of S-metolachlor + metribuzin followed …

Secure And Efficient Federated Learning, Xingyu Li

Theses and Dissertations

In the past 10 years, the growth of machine learning technology has been significant, largely due to the availability of large datasets for training. However, gathering a sufficient amount of data on a central server can be challenging. Additionally, with the rise of mobile networking and the large amounts of data generated by IoT devices, privacy and security issues have become a concern, resulting in government regulations such as GDPR, HIPAA, CCPA, and ADPPA. Under these circumstances, traditional centralized machine learning methods face a problem in that sensitive data must be kept locally for privacy reasons, making it difficult to …

Effects Of Alternative Jet Fuels On Aerospace-Grade Composites: Experimental And Modeling Studies, Naoufal Harich

Theses and Dissertations

The aviation industry aims to reduce its environmental impact through innovation and research. The usage of composite materials for multiple primary structures represents one such measure. Several alternative fuels were approved and used along with the Federal Aviation Administration (FAA). These alternative fuels are produced from wastes and biomasses. Some alternative fuels were initially only approved as drop-in fuels, meaning they must be blended with conventional fuels to operate. Fuel tanks are usually embedded into the wing structure, which is mainly made of composite materials. These composites tend to absorb fluids it encounters through their matrix phase. The absorption behavior …

Understanding Dietary And Thermal Influences On Invasive Cichlids In Puerto Rico Reservoir Systems, Jacob A. Moreland

Theses and Dissertations

Jaguar Guapote (Parachromis managuensis) and Amphilophus spp. were assessed for effects of temperature on standard metabolic rate (SMR) and lower dissolved oxygen tolerance (LDOT), efficacy of gastric lavage for diet analysis, and diet in Puerto Rico reservoirs. Fish were acclimated to 22°C, 28°C, and 34°C and SMR and LDOT were measured using intermittent respirometers. Jaguar Guapote acclimated to 34°C had the greatest SMR, with 22°C and 28°C having similar SMR values. Amphilophus spp. acclimated to 28°C were similar to fish acclimated at 22°C and 34°C. Fish were resilient to high temperatures, losing equilibrium more rapidly at the coldest temperature, 22°C. …

Eating German, The American Way: German And American Cooking Traditions, Potato Salad, And The Culinary Assimilation Of German Immigrants, 1820-1920., Scott Wooley

Theses and Dissertations

“Eating German, the American Way” explores how and why the mayonnaise-based potato salad came to be a staple of American culinary tradition. It examines how native-born Americans and German immigrants in the nineteenth century identified themselves based on their culinary traditions and what they ate and how the interactions between, and accessibility of, those traditions created a new identity based on the sharing of recipes as the two groups mingled and assimilated to each other. It uses food as a way to understand the processes of assimilation by defining the distinctions between the two groups based on their separate repertoire …

Protecting The Vulnerable: Tornado Sheltering And Communication Of Public Shelters With A Case Study From The Covid-19 Pandemic, Craig Douglas Croskery

Theses and Dissertations

One of the greatest natural hazards that is faced with in much of the United States are tornadoes. Despite improvements in the warning processes, the risk of significant loss of life remains high. That is particularly true with vulnerable communities which have higher proportions of mobile homes; however, violent tornadoes are very difficult to manage in permanent homes or buildings as well. As a result, tornado shelters have been built in some communities and have become available to the public. However, their presence is intermittent, and there are many tornado-prone areas that lack such shelters.

After a public survey, it …