Digital Commons Network^™

California 4-H Computer Science Education Pathway, Steven M. Worker, Roshan Nayak, Fe Moncloa

The Journal of Extension

Young people need digital competency and confidence to effectively harness computing power to solve problems and design solutions; a core component is improving young people’s computational thinking. Unfortunately, access to computer science education is lacking for all youth, and in particular for youth who live in lower-income households, who are Black or Latino, or live in rural areas. With funding from Google, through the National 4-H Council, California 4-H embarked on a three-year project to build the capacity of 4-H professionals, volunteers, and teenagers to facilitate computer science education with youth. Our programming was effective as assessed with survey methodology. …

Deep Reinforcement Learning Of Variable Impedance Control For Object-Picking Tasks, Akshit Lunia

All Theses

The increasing deployment of robots in industries with varying tasks has accelerated the development of various control frameworks, enabling robots to replace humans in repetitive, exhaustive, and hazardous jobs. One critical aspect is the robots' interaction with their environment, particularly in unknown object-picking tasks, which involve intricate object weight estimations and calculations when lifting objects. In this study, a unique control framework is proposed to modulate the force exerted by a manipulator for lifting an unknown object, eliminating the need for feedback from a force/torque sensor. The framework utilizes a variable impedance controller to generate the required force, and an …

Digital Twin In Military Ground Vehicles: Design And Predictive Maintenance, Conner W. Eddy

All Theses

Digital twin technology builds upon virtual engineering models, computer simulation, and real-time field data streaming to enable next-generation designs and predictive maintenance. A digital twin is a computer-based high-fidelity collection of models that predicts the performance of dynamic systems per operating cycles, input feature parameters, and data communication from a physical plant. Product Lifecycle Management (PLM) is growing in importance and is central to virtual design processes where the digital twin toolset fits into this emerging architecture. The product design process can be advanced using digital twin resources by eliminating the need for, and cost from, continual physical prototyping, reliability …

Analytical And Experimental Studies To Support Codification Of Lightweight Grout For Masonry Design, Cooper Banks

All Theses

Lightweight (LW) aggregates have many potential benefits in masonry construction including minimizing mass, improving thermal performance, and reducing the potential for shrinkage cracking via internal curing. The current masonry design standard, TMS 402/602-22, permits lightweight aggregate in the production of concrete masonry units (CMU), but there has been insufficient testing of masonry assemblies to permit designing with LW grout. Shrestha et al. characterized LW grouts bond to reinforcement, shear strength, tension and shear pullout behavior of anchors and proposed possible reduction factors for design. Hiner characterized the flexural bond strength LW grouted masonry assemblies and proposed possible reduction factors for …

Layered Structure Protonic Ceramic Conductors Of The Form Ba5in2+Xal2zr1-Xo13-Δ, Nathan Cretegny

All Theses

In this work, the hexagonal perovskite of targeted composition Ba₅In_2+xAl₂Zr_1-xO₁₃ (x=0, 0.1, 0.2) was synthesized via a solid-state synthesis route to study the impact of oxygen vacancy concentration in layered hexagonal perovskites. Precursor oxides were mixed in stoichiometric proportions, calcined between 800-1200℃ and sintered at 1475℃. The sintered pellets were crushed into fine powders to investigate the chemistry and structure through X-ray diffraction, neutron diffraction, inductively coupled plasma mass spectrometry, and nuclear magnetic resonance. Dense pellets were used to study conductivity properties using electrochemical impedance spectroscopy.

The synthesis approach produced 100% …

Defining And Labeling Traversable Space In A Forested Environment, James Nguyen

All Theses

This thesis investigates the problem of identifying traversable terrain in outdoor conditions. We are motivated by research in recent years toward identifying drivable space for the purpose of developing autonomous vehicles. Our motivating application is similar but also different. We envision a “Hiker Helper” that assists humans with dismounted navigation in forested terrain. A common challenge in this type of environment is identifying a viable path for moving through terrain that is congested with trees, bushes, other flora, and natural obstacles that would make navigation difficult. We envision training an artificial intelligence (AI) model to automatically analyze images of this …

A Transdisicplinary, Survivor-Centered Approach For Creating A System Dynamics Model Of Closed-Buyer Sex Trafficking Networks, Kemonte Yow

All Theses

One of the largest drivers of sex trafficking operations is the demand for commercial sex. To date, research from a quantitative side typically focuses on understanding how to best identify and remove victims from their trafficking situation and then support their healing and recovery. This may be because this is where data exists (in limited forms) to support quantitative modeling. This thesis broadens that scope to understand how demand for commercial sex impacts trafficking operations. In particular, this research implemented a transdisciplinary, survivor-centered approach to build a system dynamics model of a closed-buyer sex trafficking network, which is a network …

Improved Ballistic Impact Resistance Of Nanofibrillar Cellulose Films With Discontinuous Fibrous Bouligand Architecture, Colby Caviness

All Theses

Natural protective materials offer unparalleled solutions for impact-resistant material designs that are simultaneously lightweight, strong, and tough. Particularly, the dactyl club of mantis shrimp features chitin nanofibrils organized in a Bouligand structure, which has been shown to effectively dissipate high-impact energy during powerful strikes. The mollusk shells also achieve excellent mechanical strength, toughness, and impact resistance with a staggered, layer-by-layer structure. Previous studies have shown that hybrid designs, by combining different bioinspired microstructures, can lead to enhanced mechanical strength and energy dissipation capabilities. Nevertheless, it remains unknown whether combining Bouligand and staggered structures in nanofibrillar cellulose (NFC) films, forming a …

Development Of A Cost-Affordable Thin-Layer Chromatography Testing Kit For Falsified And Substandard Pharmaceuticals In Tanzania, Eleanor Hatcher

All Theses

A significant number of pharmaceuticals supplied to Tanzania are falsified or substandard. A majority of these inadequate pharmaceuticals are medications to treat life-threatening conditions. This problem not only causes mistrust in the healthcare system but also prolonged illness and potentially death for the patients. This calls for the need for the development of a cost-affordable testing kit for falsified and substandard pharmaceuticals in Tanzania. Thin-layer chromatography (TLC) was used as the testing method since it is inexpensive and requires a low skill level to complete. Malaria, human immunodeficiency virus, hypertension, tuberculosis, and diabetes are five of the most prevalent diseases …

Depression And Anxiety: Investigating The Impacts Of Scheduling On The Mental Health Of Healthcare Workers During The Covid-19 Pandemic, Christofer Gonzaga

All Theses

Depression is a growing problem in the United States and has ballooned into a globally recognized mental health issue that affects shift workers in various fields (Lee et al., 2017). Rates of depression and anxiety have been shown to be substantially increasing and the COVID-19 pandemic amplified this prevalence of depression and anxiety. In the United States, the prevalence of depression symptoms was more than 3- fold higher during COVID-19 compared to before the pandemic (Ettman et al., 2020). The delivery of healthcare services is an ongoing and dynamic process, requiring clinicians to work in various shifts to ensure the …

Multi-Domain Secure Dds Networks For Aerial And Ground Vehicle Communications, Daniel Pendleton

All Theses

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Light-Induced Phase Separation Purification For Monoclonal Antibodies, Xuyang Chen

All Theses

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Broadening The Application Range Of Cell-Free Protein Expression Systems, Matthew Becker

All Theses

Centralized protein manufacturing platforms make the delivery of needed therapies to places with limited infrastructure almost impossible. Cell-free protein expression systems, systems that utilize protein production machinery extracted from cells, offer these communities a viable protein expression platform that is robust and easily deliverable to the place of need. Much work in cell-free system engineering looks to increase the hardiness of cell-free system (CFS) components, like the extract and reaction buffer, needed to carry transcription and translation of gene therapeutic targets forward. Freeze- and air-drying of extract, reaction buffer, or both with certain additives, like sugar molecules, has been proposed …

Engineering Sustainable Bridge Deck Rehabilitation: Evaluating Mechanical And Electro-Chemical Properties Of Rapid-Set Patching Materials And Their Influence On Repair Durability, James Roberts

All Theses

As the state of the US infrastructure continues to deteriorate over time, a prominent issue especially in the field of reinforced concrete structures has been the ability to properly rehabilitate and extend the design service life of these structures. A majority of our existing reinforced concrete bridges were built in the construction boom during the 60’s, 70’s and 80’s, and were originally designed with a service life of approximately 50 years, thus showing that many structures are close to or have already exceeded their intended service life. Additionally, with a poor history of government infrastructure funding, it is seen to …

Efficacy Of Virtual Reality-Based Simulations In Training Aviation Maintenance Technicians On Maintenance Procedures, Gayatri Anoop

All Theses

The COVID-19 pandemic forced institutions of higher education (IHEs) to halt in-person classes and transition to online platforms. Given the intricate process of adapting hands-on experiments to the online environment, this transition seemed particularly challenging for Science, Technology, Engineering, Mathematics, and Medicine (STEMM) labs. The abrupt nature of this transition added to the difficulties, given that the IHEs were inadequately prepared for seamless continuity during the pandemic. In the first phase of this project, a literature review was conducted to understand the impact of COVID-19 pandemic on education. Specifically, the review explored the challenges that institutions of higher education faced, …

Analyzing An In-Line Compression Management System For Improved Performance In A High-Performance Computing Environment, Steven Platt

All Theses

High-performance computing (HPC) has enabled advancements in computation speed and resource cost by utilizing all available server resources and using parallelization for speedup. This computation scheme encourages simulation model development, massive data collection, and AI computation models, all of which store and compute on massive amounts of data. Data compression has enhanced the performance of storing and transferring this HPC application data to enable acceleration, but the benefits of data compression can also be transferred to the active allocated memory used by the application. In-line compression is a compression method that keeps the application memory compressed in allocated memory, decompressing …

“How Are High School Counselors Prioritizing The Information Relevant To Stem Career Preparation In Their Communication With Stem-Interested African American Students?”, Wysheka Austin

All Dissertations

Although African Americans and other minoritized groups have gradually increased in the number of students graduating with a Science, Technology, Engineering, and Mathematics (STEM) degree over the years, these groups remain underrepresented in STEM. Among the many factors contributing to the lack of representation is “college readiness,” which includes academic preparation and awareness of the necessary steps needed for college admission and career preparation [5]. South Carolina policy only considers academic preparation in their assessment of college readiness. To measure academic preparation of any student, the state relies on standardized test scores and advanced course taking without regard to subject. …

Development And Application Of Discrete Element Models For Granular Materials - From Rigid Spheres To Complex-Shaped Flexible Particles With Breakage, Zakia Tasnim

All Dissertations

Granular materials, which can range from nanometers to centimeters, are widely encountered as particles or powders in nature and in engineered systems. Some examples of granular materials include sands, gravels, biomass feedstocks, rice grains, pharmaceutical pills, glass beads, and lunar or martian regolith simulants. The attributes of and the interactions between constituent particles dictate the bulk mechanical properties and behavior of granular materials. The discrete element method (DEM), a particle-based modeling technique, has become a useful numerical tool for modeling the bulk behavior (such as mechanical, flow, and breakage behavior) of granular materials, where interactions between the granular materials' individual …

Evacuation Of Students With Intellectual Disability In Building Fires: A Three-Part Methodology, Haley Hostetter

All Dissertations

People with disabilities are one of the most vulnerable groups in building fires. Despite this, they have traditionally been overlooked by fire evacuation researchers. This is perhaps the most alarming for the group with Intellectual Disability when given their present statistics for fire involvement, injuries, and death. Annually, people with mental disabilities are involved in 1700 home fires, resulting in 39 fatalities and 122 injuries per 1000 fires. Additionally, 40% of these fires were started intentionally by people with mental disabilities. When combined with their high fire risk, the lack of evacuation research focused on people with Intellectual Disability shows …

Real-Time Degradation Abatement Framework For Energy Storage System In Automotive Application Using Data-Driven Approaches, Laxman Timilsina

All Dissertations

The increasing popularity of electric vehicles (EVs) is driven by their compatibility with sustainable energy goals. However, the decline in the performance of energy storage systems, such as batteries, due to their degradation puts EVs and hybrid electric vehicles (HEVs) at a disadvantage compared to traditional internal combustion engine (ICE) vehicles. The batteries used in these vehicles have limited life. The degradation of the battery is accelerated by the operating conditions of the vehicle, which further reduces its life and increases the reliability and economic concerns for the vehicle’s operation. The aging mechanism inside a battery cannot be eliminated but …

Additive Manufacturing Of Porous Tungsten Carbide Structural Electrode Components Using Robocasting, James Bevis

All Theses

Thanks to ideal mechanical and electrochemical properties, Tungsten Carbide (WC) shows excellent potential as a structural electrode material for multifunctional devices. These devices have applications in electric vehicles, for example, structural fuel cells and massless batteries. In such a context, structural WC electrodes will also benefit from porosity to decrease their weight and increase their surface area and chemical reactivity. Porous WC is a useful material for this field because of its high strength-to-weight ratio and electrical properties. However, current manufacturing methods can be expensive, complex, and limited, so the intent is to provide a more simplistic and sustainable method …

Design, Fabrication, And Characterization Of Advanced High-Power Single-Mode 9xxnm Semiconductor Lasers, Xiaolei Zhao

All Dissertations

This thesis presents the comprehensive design, fabrication, and demonstration of advanced high-power, high-efficiency single-mode semiconductor lasers operating at a wavelength of 9xxnm. We begin with the design of the laser epitaxial structure, serving as the cornerstone for achieving high-power high-efficiency lasers. Our methodology integrates a semi-analytical calculation model, which accounts for Longitudinal Spatial Hole Burning (LSHB) and Two-Photon Absorption (TPA) effects, facilitating a thorough exploration of how design parameters influence output power and conversion efficiency. This approach offers an effective and time-efficient epitaxial structure optimization strategy compared to conventional full 3D simulation models.

Subsequently, we demonstrate high-power, high-efficiency ridge waveguide …

Robust And Trustworthy Deep Learning: Attacks, Defenses And Designs, Bingyin Zhao

All Dissertations

Deep neural networks (DNNs) have achieved unprecedented success in many fields. However, robustness and trustworthiness have become emerging concerns since DNNs are vulnerable to various attacks and susceptible to data distributional shifts. Attacks such as data poisoning and out-of-distribution scenarios such as natural corruption significantly undermine the performance and robustness of DNNs in model training and inference and impose uncertainty and insecurity on the deployment in real-world applications. Thus, it is crucial to investigate threats and challenges against deep neural networks, develop corresponding countermeasures, and dig into design tactics to secure their safety and reliability. The works investigated in this …

Evaluating Company Culture Of Roofing Contracting Companies To Attract And Retain Women In The Industry, Gopika Viswanathan

All Theses

The US construction industry, similar to many other industries, has a low representation of women. This difference is even more pronounced in construction trades, such as the roofing industry. The admission of more women into the industry is important to address workforce shortage issues that the industry is facing. Company culture has been cited as one of the primary reasons why women choose not to enter the industry or face barriers during their careers. The main objective of this study was to evaluate the company culture of roofing companies through factors identified by literature and by women and companies in …

Release Of Small Molecules From Rubber: Effects Of Materials Properties, Mechanical Loading And Molecular Interactions, Yongcan Du

All Dissertations

Release of small molecules from polymeric materials has wide applications in the delivery systems of active molecules such as drug, fragrance, and semiochemical. Rubber materials are good candidates for the excipients of those systems due to properties such as good flexibility, permeability, and biocompatibility. Factors like material properties, mechanical loading, and molecular interactions may affect the release of small molecules in those systems. Therefore, understanding how those factors affect the release is key to the formulation, design, and evaluation of those systems.

To study the effects of materials properties, vulcanized natural rubber sheets with different crosslink densities, loaded with small …

A Comprehensive Materials Approach To Thermal Management In Fiber Lasers, Bailey Meehan

All Dissertations

Optical fiber-based amplifiers and lasers enable a great many useful devices and conveniences. Unfortunately, however, they can generate considerable heat during operation that drives the need for complex cooling solutions, thus reducing many of the size, weight, and power (SWAP) benefits for which fiber lasers are known. Additionally, at elevated temperatures, thermally-driven phenomena, such as Transverse Mode Instability (TMI), can be induced that limit the power-scaling of fiber lasers. The focus of this Dissertation is to explore novel approaches to thermal management in fiber lasers through judicious materials science and engineering to obviate the aforementioned limitations. Fibers studied in this …

Evaluation And Development Of Tourniquet Test Methods, Catherine Pitts

All Theses

Since the beginning of the 21^st century the general perspective on tourniquets has changed to a more positive outlook on their life saving abilities. The US has seen a greater number of mass casualty events, and conflicts across the globe have led to an increased use of tourniquets. The increased demand has also led to faulty counterfeit tourniquets and improvised tourniquets that don not properly occlude blood flow or cause significant nerve damage to the injured limb.

ASTM started designing a tourniquet testing standard with experts in the tourniquet community to cut down on the dangers of tourniquet use. …

Modeling Of Multi-Period Disaster Logistics Planning In The State Of South Carolina, Emma Simon

All Theses

South Carolina is one of the most vulnerable states in the United States to the impact of hurricanes. Currently, when threatened with a natural disaster such as a hurricane, the state government makes many vital decisions based on knowledge and experience. In this study, the distribution of disaster relief commodities to meet immediate needs is analyzed through two models for the case of South Carolina to generate an optimal logistics strategy that considers the social vulnerability of affected populations. The first model is a multi-objective pre-disaster logistics model that uses a four-index formulation for the multiple trip vehicle routing problem. …

Phasor-Domain Short-Circuit Analysis Of Power Transmission Systems In The Presence Of Inverter-Based Resources, Dol Kunwar

All Theses

Although a power system is nonlinear during healthy operation because of constant power loads and controlled power injections from the sources, a conventional power system fed by synchronous generators is linear during fault, and can be represented by bus impedance matrix (Z-bus), which is useful in power system analyses such as short circuit (SC) analysis. However, With increasing penetration of inverter-based resources (IBRs) in the system, the assumption of linearity of the faulted network does not hold. This impacts the analyses relying on Z-bus and Thevenin’s equivalent impedance (TEI), such as certain protection schemes set using short circuit analysis. Therefore, …

Development And Evaluation Of An Arsenic Transport Model For The Maurice River Watershed, Christina Eddleman

All Theses

For many Superfund sites across the United States, arsenic is one of the most common contaminants of concern that must be cleaned up to protect human and environmental health. Past research and health studies have documented the harmful effects of inorganic arsenic on humans and the environment but selecting an appropriate remediation plan depends on several site-specific factors at each Superfund site. To assist in determining an appropriate remediation plan, sediment and contaminant transport models have been used to simulate the transport of arsenic and other contaminants of concern at contaminated sites to, e.g., make relative comparisons of the efficacy …