Engineering Commons^™

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 …

Hand Movement Analysis For Surgical Suturing Skill Assessment, Amir Mehdi Shayan

All Theses

To enhance patient safety, surgical education is increasingly incorporating simulation for formative skills assessment and training. However, many standardized assessment tools rely on human raters for performance assessment, which is resource-intensive and subjective. Simulators that provide automated and objective metrics from sensor data can address this limitation. This thesis presents an instrumented bench suturing simulator, patterned after the Clock Face (CF) radial suturing model from the Fundamentals of Vascular Surgery (FVS), for automated and objective assessment of open suturing skills by particularly focusing on biomechanical analysis of hand movements. For this research, 97 participants (35 attending surgeons and fellows, 32 …

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 …

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 …

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 …

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, …

The Effect Of Football Facemask Design Variability On Dynamic Impact Performance And Quasi-Static Stiffness, Adam W. Smith

All Theses

This research addresses the role of facemasks in helmet systems, focusing on their dynamic impact performance and material properties. A total of 150 facemasks from 30 types and five helmets were tested both quasi-statically and dynamically. The facemasks were grouped by style and helmet type for comparison. Dynamic testing involved three different locations and two speeds, with data collected for maximum angular velocity and linear acceleration. Quasi-static stiffness, performed at two locations, was compared with collected dynamic results to determine the strength of relationship. A concussion metric, HARM, was calculated from collected data and compared across style groups.

Significant differences …

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

All Theses

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Recommender System Design And Multi-Channel Pricing: Personalization Strategies For Online Platforms, Hao Zhang

Dissertations and Theses Collection (Open Access)

The advancement of mobile technology and rising consumer demands have contributed to the unprecedented growth of online platforms. In online platforms, recommender systems connect with multistakeholders who have different interests. Designing recommender systems to balance the benefit of multistakeholders is important for these platforms. In addition, price is an important factor influencing consumers’ purchase decisions. An increasing number of online platforms introduce multiple sales channels. Optimizing multiple-channel prices is vital for these platforms. Thus, this thesis designs multistakeholder recommender systems and multi-channel pricing strategies for online platforms through the following two works.

The first work focuses on designing multistakeholder recommender …

The Second-Order Features Adjoint Sensitivity Analysis Methodology For Response-Coupled Forward/Adjoint Linear Systems (2nd-Fasam-L): Mathematical Framework And Illustrative Application To An Energy System, Dan Gabriel Cacuci

Faculty Publications

The Second-Order Features Adjoint Sensitivity Analysis Methodology for Response-Coupled Forward/Adjoint Linear Systems (abbreviated as “2nd-FASAM-L”), presented in this work, enables the most efficient computation of exactly obtained mathematical expressions of first- and second-order sensitivities of a generic system response with respect to the functions (“features”) of model parameters. Subsequently, the first- and second-order sensitivities with respect to the model’s uncertain parameters, boundaries, and internal interfaces are obtained analytically and exactly, without needing large-scale computations. Within the 2nd-FASAM-L methodology, the number of large-scale computations is proportional to the number of model features (defined as functions of model parameters), as opposed to …

Stabilization Of Layered Transition Metal Oxide Positive Electrodes At High Potential For Sodium Ion Batteries, Eric Gabriel

Boise State University Theses and Dissertations

As global demand for energy storage rises in response to the proliferation of electric vehicles and intermittent renewable energy sources, the resources associated with popular energy storage systems are increasingly strained. Lithium ion batteries (LIBs) rely heavily on elements with low abundance and unstable supply chains, while sodium ion batteries (SIBs) are a promising alternative technology based on abundant, globally available elements such as iron and sodium. However, the electrochemical performance of SIBs must be improved to enable their commercial viability. In the class of layered transition metal oxide (LTMOs) materials that are strong candidates as positive electrode materials for …

Development And Characterization Of A Low Intensity Vibrational System For Microgravity Studies, Omor Khan

Boise State University Theses and Dissertations

The advent of extended-duration human spaceflight demands a better comprehension of the physiological impacts of microgravity. One primary concern is the adverse impact on the musculoskeletal system, including muscle atrophy and bone density reduction. Ground-based microgravity simulations have provided insights, with vibrational bioreactors emerging as potential mitigators of these negative effects. Despite the potential they have, the adaptation of vibrational bioreactors for space remains unfulfilled, resulting in a significant gap in microgravity research. This paper introduces the first automated low-intensity vibrational (LIV) bioreactor designed specifically for the International Space Station (ISS) environment. Our research covers the bioreactor's design and characterization, …

On-Chip Active Pulse-Clamp Stimulation (Apcs) For Rapid Recovery, Charge-Balanced Neural Stimulation, F. N. U. Tala

Boise State University Theses and Dissertations

Neurostimulations are widely utilized to modulate brains and nervous systems functions for therapeutic purposes. Traditional neurostimulation involves applying a direct current delivered to the excitable tissues to elicit neural response. There is a growing demand for a robust, rapid stimulation system that ensures chronic safety through charge balancing in vivo. This dissertation is a compilation of previously published works, detailing various board-level stimulators, an innovative on-chip stimulation technique, and a distributed modelling method.

Chapter one introduces MEDUSA, a cost-effective, multi-functional neurostimulation system capable of achieving multi-channel, arbitrary stimulation for neuroscience research.

Chapter two delves into a scripted distributed model framework …

Titanium Dioxide Nanomaterial Ink Production Through Laser Ablation Synthesis In Solution For Printed Electronics Applications, Devyn Duryea, Nicholas Mckibben, Jacob Manzi, Taylor Brennan, Harish Subbaraman, David Estrada, Nirmala Kandadai

Electrical and Computer Engineering Faculty Publications and Presentations

Flexible and printed electronics have become increasingly popular as they make possible the production of flexible, low-cost, multifunction devices that are unachievable through traditional manufacturing methods. The printed films are significantly impacted and thus limited by the existing ink production process. Herein, an alternate technique of generating high-quality titanium dioxide (TiO₂) nanoparticle ink compatible with aerosol jet printing using laser ablation synthesis in solution (LASiS) is showcased. Dynamic light scattering data and transmission electron microscopy confirm the particle size distribution. UV–vis measurements are performed, and the Beer–Lambert relationship is used to determine the concentration of the generated ink. …

Bay Water Level Influences On Inundation And Morphological Changes Of A Semi-Connected Barrier Island During A Hurricane, Sydney D. Goodman

Graduate Theses and Dissertations (2019 - present)

This research aims to identify flooding and erosion changes along a semi-connected barrier island system due to varying bay water levels during storm conditions. The numerical model XBeach is used to simulate Hurricane Michael conditions and the resulting inundation and morphological change near Tyndall Air Force Base (Tyndall AFB). The installation is located 12 miles southeast of Panama City Beach along the panhandle of Florida and is vulnerable to flooding due to its proximity to the Gulf of Mexico (GoM), Saint Andrew Sound and Saint Andrew Bay. A land bridge connects the barrier island to the mainland of Tyndall AFB …

On-Demand Fabrication Of Piezoelectric Sensors For In-Space Structural Health Monitoring, Amanda White, Isaac Little, Anastasiya Artyuk, Nicholas Mckibben, Fereshteh Rajabi Kouchi, Claire Chen, David Estrada, Zhangxian Deng

Mechanical and Biomedical Engineering Faculty Publications and Presentations

Inflatable structures, promising for future deep space exploration missions, are vulnerable to damage from micrometeoroid and orbital debris impacts. Polyvinylidene fluoride-trifluoroethylene (PVDF-trFE) is a flexible, biocompatible, and chemical-resistant material capable of detecting impact forces due to its piezoelectric properties. This study used a state-of-the-art material extrusion system that has been validated for in-space manufacturing, to facilitate fast-prototyping of consistent and uniform PVDF-trFE films. By systematically investigating ink synthesis, printer settings, and post-processing conditions, this research established a comprehensive understanding of the process-structure-property relationship of printed PVDF-trFE. Consequently, this study consistently achieved the printing of PVDF-trFE films with a thickness of …

Characterizing The Molecular And Cellular Changes Of Senescent Cells Induced By Diverse Stressors In 2d And 3d Microenvironments, Apoorva Chauhan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Aging is a risk factor for myriad diseases and is often associated with the accumulation of senescent cells. Cellular senescence, a process of irreversible cell cycle arrest, is associated with various changes in cellular morphology and function. While senescence will occur naturally in a time-dependent manner, it can be prematurely induced by various extrinsic and intrinsic factors. Most senescence studies model cell behavior in two-dimensional (2D) microenvironments; however, these models are not physiologically relevant. In this study, the effects of naturally occurring reactive oxygen species (ROS) hydrogen peroxide (H2O2) and commonly used chemotherapy drugs, doxorubicin and palbociclib, on cellular senescence …

Experiment Development And Validation Of A Granular Jamming Robotic Gripper, Jacob R. Dowd

UNLV Theses, Dissertations, Professional Papers, and Capstones

A granular jamming gripper (GJG) is widely known as a Universal Gripper because of the wide range of objects that it can grasp and the simplicity of control, design, and manufacturing. Despite multitude of research improving the GJG, here, we focus on the base version of the GJG and attempt to glean the range of objects that it may reliably grasp. Despite the limited range of objects, which were a sphere, rectangular prism, and cylinder, we gleaned geometric properties as it relates to successful and unsuccessful grasping. This was based on the two types of testing: push and pull testing …

Analyses Of Thermal And Spectral Characteristics Of Artificial Turf And Natural Grass In Las Vegas Valley, Tarannum Kalam Khandoker

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis presents a comprehensive analysis of the thermal and spectral characteristics of Las Vegas Valley (LVV). The first objective examines the effects of artificial turf on the urban thermal environment in the LVV by analyzing the impact of Land Surface Temperature (LST) and surface albedo at 26 ROIs that transitioned from natural to artificial turf, alongside another 26 ROIs that remained unchanged between 2018 and 2022 utilizing available Landsat 8 satellite images for the respective years. In the comprehensive comparison of ROIs over the two years in question, it was observed that transitioning to artificial turf correlated with elevated …

Investigative Research On Design Parameters And Criticality Models For Microreactors, Cameron Jensen

UNLV Theses, Dissertations, Professional Papers, and Capstones

With increased energy demand and the desire to reduce reliance on fossil fuels, nuclear power will need to play a prominent role in achieving carbon-free energy independence. Large nuclear reactors are necessary to meet this objective. However, they are expensive and take a long time to build. For remote locations (e.g., military bases) and smaller communities, large nuclear reactors would not be feasible or cost effective. Small reactors (microreactors) can fill this necessary gap. These reactors would be factory-built, delivered quickly, and operated with high intrinsic levels of safety. With microreactors still in conceptual and testing states, there is a …

Principles And Practices For Creating Inherently Resilient Smallsats Despite Constrained Resources, Lee Jasper, Tyler De Caussin

Space Dynamics Laboratory Publications

Over the past few years, small satellites have become heavily utilized for both constellations and single vehicle missions. Many organizations have learned how to be successful with these platforms however, while small, they are not simple systems and first-time creators of these systems still suffer high rates of failure. AFRL's Small Satellite Portfolio has established guiding practices/principles for satellite design that help reduce overall mission risk based upon both community and internal lessons learned. These principles help make the design technically resilient and can also help with programmatic execution. This paper will discuss the principles with some detail (such as …

Development And Evaluation Of A Modeling Platform For Evaluating Immunotherapeutic Efficacy In The Tumor Microenvironment., Dylan Andrew Goodin

Electronic Theses and Dissertations

The tumor microenvironment (TME) represents the complex outcome of numerous tumor, stromal, and immune interactions, and whose composition can significantly affect treatment response. Particularly, immunotherapeutic efficacy is subject to multiple tumor-specific TME interactions that may be difficult to evaluate/predict clinically. Mathematical modelling has been formulated to evaluate specific aspects of the TME, including vasculature, ECM deposition, and immune-tumor interactions. However, the computational challenge of simulating multiple TME interactions has led to sacrificing varying degrees of model generalizability and clinical relevance. This work describes increased computational performance of a 3D continuum model that simulates tumor tissue, ECM, and vasculature using a …

Novel Designs Of Soft Tactile Sensor And Robot Finger Manipulator Based On Optical Fibers., Seokyoung Han

Electronic Theses and Dissertations

Robotic manipulation is one of the main types of automated labor that humans want to achieve in order to free ourselves from mundane and hazardous tasks. The range of realizations could be very broad, from massive industrial robots to highly advanced medical devices for human healthcare. Given the critical nature of these application spaces, they require robust, safe, and most of all versatile designs. In that direction, one of the most interesting topics is the anthropomorphic robotic manipulator. Since it is inspired by human hands’ function and structure, it is able to achieve the aforementioned system requirements. However, the perfect …

Electrokinetic Particle Trapping Performance Of Conductive Nanofiber Mats In Microfluidic Wells., Jacob Hunter West

Electronic Theses and Dissertations

The frequency dependence of electrokinetic particle trapping using large-area (>mm²) conductive carbon nanofiber (CNF) mat electrodes is investigated. The fibers provide nanoscale geometric features for the generation of high electric field gradients, which is necessary for particle trapping via dielectrophoresis (DEP). A device was fabricated with an array of microfluidic wells for repeated experiments; each well included a CNF mat electrode opposing an aluminum electrode. Fluorescent microspheres (1 µm) were trapped at various electric field frequencies between 30 kHz – 1 MHz. Digital images of each well were analyzed to quantify particle trapping. DEP trapping by the …

Emergency Vehicle Prioritization In Connected And Autonomous Traffic., Mohamadreza Haghani

Electronic Theses and Dissertations

Reducing the response time of emergency vehicles (EV) is highly important due to the relationship between response time and fatality rate. Emerging technologies can help reduce response time by enhancing EV prioritization. On the other hand, EV prioritization can negatively impact general traffic especially in cross streets of signalized intersections. In this research, three main objectives were followed. Firstly, creation and dissipation of EVP disruption on arterial cross streets was studied to recommend solutions to prevent this disruption. Secondly, lane-changing and stopping behavior of CAVs were studied in EV prioritization to identify the best lane-changing behavior through minimizing delay. Thirdly, …

A Design Science And Implementation Framework For Studying Interruptions And Its Application In A Dental Clinic., Carsten Ziegler

Electronic Theses and Dissertations

Interruptions during dental treatment are frequent, and often have detrimental effects on quality of care, patient safety and processing times, and have an impact on provider satisfaction and performance. Interruptions can significantly increase the cognitive load on dental providers, making it hard for them to concentrate on complex procedures. Frequent interruptions also disrupt the workflow in general, leading to delays in treatment, which can reduce the overall throughput of a clinic. Unfortunately, there is no comprehensive approach to collectively (i) analyze interruptions in dental healthcare, (ii) design an intervention, and (iii) implement and sustain it. This research proposes a comprehensive …

Attention Guided Data Augmentation For Improving The Classification Performance Of Vision Transformers., Nada Baili

Electronic Theses and Dissertations

For over a decade, Deep Neural Networks (DNNs) have been rapidly progressing and achieving great success, forming a robust foundation of state of the art machine learning algorithms that impacted various domains. The advances in data acquisition and processing have undeniably played a major role in these breakthroughs. Data is a crucial component in building successful DNNs, as it enables machine learning models to optimize complex architectures, necessary to perform certain difficult tasks. However, acquiring large-scale data sets is not enough to learn robust models with generalizable features. Instead, an ideal training set should be diverse enough and contain enough …