Engineering Commons^™

Coherent Control Of Dispersive Waves, Jimmie Adriazola

Dissertations

This dissertation addresses some of the various issues which can arise when posing and solving optimization problems constrained by dispersive physics. Considered here are four technologically relevant experiments, each having their own unique challenges and physical settings including ultra-cold quantum fluids trapped by an external field, paraxial light propagation through a gradient index of refraction, light propagation in periodic photonic crystals, and surface gravity water waves over shallow and variable seabeds. In each of these settings, the physics can be modeled by dispersive wave equations, and the technological objective is to design the external trapping fields or propagation media such …

Hydrophobically Modified Isosorbide Dimethacrylates As Biomaterials For Bisphenol A Free Dental Fillings, Bilal Marie

Dissertations

Amalgam and Bisphenol A glycerolate dimethacrylate (BisGMA) are the main dental filling materials in use today. Because of the negative perception of amalgam and its lower esthetic appeal, as well as the desire to replace the endocrine disruptor Bisphenol A, which is the building block of BisGMA, there has been a critical need to search for safer alternatives to these dental filling materials.

Isosorbide is a sugar-based molecule generally recognized as safe. It has been extensively studied as a replacement to the Bisphenol A core in various materials. However, isosorbide is extremely hygroscopic, and water uptake in dental fillings causes …

Experimental And Computational Studies Of Functionalized Carbon Nanotubes For Use In Energy Storage Devices And Membranes, Emine S. Karaman

Dissertations

Electrolytes with good interfacial stability are a crucial component of any electrochemical device. The development of novel gel polymer electrolytes (GEs) with good interface stability and better manufacturability is important for the development of the next generation electrochemical devices. Gel electrolytes are hybrid electrolyte materials, combining benefits of both liquid and solid systems. Compared with liquid and solid electrolytes, GEs open new design opportunities and do not require rigorous encapsulation methods. In this dissertation, studies on functionalized carbon nanotubes (fCNTs) and graphene oxide (GO) doped polyvinyl alcohol (PVA) based gel electrolytes (GEs) are reported. The ionic conductivity and mechanical strength …

A Practical Approach To Automated Software Correctness Enhancement, Aleksandr Zakharchenko

Dissertations

To repair an incorrect program does not mean to make it correct; it only means to make it more-correct, in some sense, than it is. In the absence of a concept of relative correctness, i.e. the property of a program to be more-correct than another with respect to a specification, the discipline of program repair has resorted to various approximations of absolute (traditional) correctness, with varying degrees of success. This shortcoming is concealed by the fact that most program repair tools are tested on basic cases, whence making them absolutely correct is not clearly distinguishable from making them relatively more-correct. …

Electric-Field-Driven Processes In Multiphase Fluid Systems, Qian Lei

Dissertations

Advantages of using electric fields in miniaturized apparatuses for a wide range of applications are revealed by numerous experimental and theoretical studies over the last several decades as it offers a simple and efficient method for manipulation of multiphase fluid systems. This approach is considered to be especially beneficial for control of boiling processes and colloidal suspensions considered in the presented work.

Boiling. Today's trends for enhancing boiling heat transfer in terrestrial and space applications focus on removal of bubbles to prevent formation of a vapor layer over the surface at a high overheat. In contrast, this dissertation presents a …

Energy Planning Model Design For Forecasting The Final Energy Consumption Using Artificial Neural Networks, Haidy Eissa

Theses and Dissertations

“Energy Trilemma” has recently received an increasing concern among policy makers. The trilemma conceptual framework is based on three main dimensions: environmental sustainability, energy equity, and energy security. Energy security reflects a nation’s capability to meet current and future energy demand. Rational energy planning is thus a fundamental aspect to articulate energy policies. The energy system is huge and complex, accordingly in order to guarantee the availability of energy supply, it is necessary to implement strategies on the consumption side. Energy modeling is a tool that helps policy makers and researchers understand the fluctuations in the energy system. Over the …

Droplet-Based Fuel Property Measurements, Wanjun Dang

LSU Doctoral Dissertations

Ongoing work to find renewable biofuels to function as drop-in replacements or blending components with gasoline has identified a large number of fuel candidates. Given the vast number of potential biomass-derived fuel molecules and limited sample sizes, screening tools are required to down-select candidate fuels having desired physical properties to ensure good engine performance. This work investigates approaches for rapid screening of candidate fuels using micro-liter sample sizes targeting four properties -- surface tension, viscosity, heat of vaporization (HOV), and vapor pressure. Measurement techniques for fuel properties are developed based on unit phenomena for liquid fuel droplets including droplet oscillation …

Soil Moisture Dependent Runoff In A Dryland Region: An Investigation Of The Role Of Antecedent Conditions, Monitoring, And Modeling Strategies, Gerhard Schoener

Civil Engineering ETDs

Approximately 30% of the Earth’s land surface is characterized as arid or semiarid, including much of the western United States. Accurate runoff predictions are important for informed watershed management, particularly in rapidly urbanizing areas. Infiltration excess overland flow is the dominant mechanism for runoff generation in many dryland basins, and event-based infiltration or loss models are commonly used to estimate runoff. However, predictions are associated with considerable uncertainty due to the role antecedent soil moisture, an initial condition that must be set by the modeler. The objectives of my research were to (1) evaluate the impact of antecedent soil moisture …

Intracavity Phase Interferometry Based Fiber Sensors, Luke Jameson Horstman

Optical Science and Engineering ETDs

Intracavity Phase Interferometry (IPI) is a detection technique that exploits the inherent sensitivity of a laser's frequency to the parameters of its cavity. Intracavity interferometry is orders of magnitude more sensitive than its extracavity alternatives. This dissertation improves on previous free-space proof-of-concept designs. By implementing the technique in fiber optics, using optical parametric oscillation, and investigating non-Hermitian quantum mechanics and dispersion tailoring enhancement techniques, IPI has become more applicable and sensitive. Ring and linear IPI configurations were realized in this work, both operating as bidirectional fiber optical parametric oscillators. The benefit of using externally pumped synchronous optical parametric oscillation is …

Robotic Olfactory-Based Navigation With Mobile Robots, Lingxiao Wang

Doctoral Dissertations and Master's Theses

Robotic odor source localization (OSL) is a technology that enables mobile robots or autonomous vehicles to find an odor source in unknown environments. It has been viewed as challenging due to the turbulent nature of airflows and the resulting odor plume characteristics. The key to correctly finding an odor source is designing an effective olfactory-based navigation algorithm, which guides the robot to detect emitted odor plumes as cues in finding the source. This dissertation proposes three kinds of olfactory-based navigation methods to improve search efficiency while maintaining a low computational cost, incorporating different machine learning and artificial intelligence methods.

A. …

Ultrafast Spectroscopy Of Air Lasing In Filaments, Brian Robert Kamer

Optical Science and Engineering ETDs

Filamentation in air is a phenomenon that has been extensively investigated for the last two decades. At sufficiently high intensity, even air is a nonlinear medium. These intensities are reached with ultrashort pulses (50 to 100 fs) of more than 1 J energy, which self-focus in air, reach ionizing intensities of oxygen and nitrogen, creating a plasma that defocuses the beam. The air filament is a self-induced waveguide resulting from a balance of focusing and defocusing. In this work new techniques were developed to visualize and analyze this phenomenon through its emission, in particu- lar the UV emission of the …

Interfacial Engineering And Photoelectrochemistry Of Patterned Metal/Semiconductor Heterostructures, Che Tan

McKelvey School of Engineering Theses & Dissertations

Photoelectrochemical (PEC) cells enable the conversion of solar energy into storable fuels, which is critical in overcoming the intermittent nature of this largest renewable source. However, the majority of semiconductors used as photoelectrodes in these cells have low conversion efficiencies and/or stabilities. Silicon (Si) is an attractive semiconductor material for photoelectrodes, but the development of efficient Si-based photoanodes is challenging due to their instability in alkaline solutions. Thus, one focus of this dissertation is the design and fabrication of highly stable nickel (Ni)-patterned Si photoanodes through interfacial engineering of the barrier heights. Recently, hot carriers in plasmonic metal nanostructures have …

Lunar Regolith Simulant Behaviours Affected By Shock Metamorphism And Mineralogy, Xiao Chen Zhang

Electronic Thesis and Dissertation Repository

There are still many gaps in improving the fidelity of lunar regolith simulants to simulate more properties. This study compares some fundamental physical and mineralogical properties of three types of lunar highland regolith simulants: LHS-1, a commercial product with high mineralogical fidelity; UWO-1G, an original simulant that is the main component of LHS-1; and UWO-1S, another original product that is attempted to produce shocked grains in lunar simulants from pulverizing and mixing impact rocks sourced from the Mistastin Crater.

Preliminary results indicated that even though all simulants are composed of mostly plagioclase minerals and have similar particle size distribution patterns, …

Uncertainty-Aware Deep Learning For Prediction Of Remaining Useful Life Of Mechanical Systems, Samuel J. Cornelius

Theses and Dissertations

Remaining useful life (RUL) prediction is a problem that researchers in the prognostics and health management (PHM) community have been studying for decades. Both physics-based and data-driven methods have been investigated, and in recent years, deep learning has gained significant attention. When sufficiently large and diverse datasets are available, deep neural networks can achieve state-of-the-art performance in RUL prediction for a variety of systems. However, for end users to trust the results of these models, especially as they are integrated into safety-critical systems, RUL prediction uncertainty must be captured. This work explores an approach for estimating both epistemic and heteroscedastic …

The Development Of Authentic Virtual Reality Scenarios To Measure Individuals’ Level Of Systems Thinking Skills And Learning Abilities, Vidanelage L. Dayarathna

Theses and Dissertations

This dissertation develops virtual reality modules to capture individuals’ learning abilities and systems thinking skills in dynamic environments. In the first chapter, an immersive queuing theory teaching module is developed using virtual reality technology. The objective of the study is to present systems engineering concepts in a more sophisticated environment and measure students learning abilities. Furthermore, the study explores the performance gaps between male and female students in manufacturing systems concepts. To investigate the gender biases toward the performance of developed VR module, three efficacy measures (simulation sickness questionnaire, systems usability scale, and presence questionnaire) and two effectiveness measures (NASA …

A Longitudinal Analysis Of Pathways To Computing Careers: Defining Broadening Participation In Computing (Bpc) Success With A Rearview Lens, Mercy Jaiyeola

Theses and Dissertations

Efforts to increase the participation of groups historically underrepresented in computing studies, and in the computing workforce, are well documented. It is a national effort with funding from a variety of sources being allocated to research in broadening participation in computing (BPC). Many of the BPC efforts are funded by the National Science Foundation (NSF) but as existing literature shows, the growth in representation of traditionally underrepresented minorities and women is not commensurate to the efforts and resources that have been directed toward this aim.

Instead of attempting to tackle the barriers to increasing representation, this dissertation research tackles the …

Impurity Production And Transport In The Prototype Material Plasma Exposure Experiment, Clyde J. Beers

Doctoral Dissertations

The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) is a linear pulse plasma device at Oak Ridge National Laboratory with the purpose of doing the research and development for the heating concepts on the planned full MPEX device. The goal of MPEX is to perform material studies at fusion relevant conditions. To understand the conditions at the material target for performing plasma-material interaction studies the ion temperature and density, the electron temperature and density, and the particle flux and fluence must be known. Impurities within Proto-MPEX can alter the desired conditions at the material target and need to be understood for …

A Connectivity Framework To Explore The Role Of Anthropogenic Activity And Climate On The Propagation Of Water And Sediment At The Catchment Scale, Christos Giannopoulos

Doctoral Dissertations

Anthropogenic disturbance in intensively managed landscapes (IMLs) has dramatically altered critical zone processes, resulting in fundamental changes in material fluxes. Mitigating the negative effects of anthropogenic disturbance and making informed decisions for optimal placement and assessment of best management practices (BMPs) requires fundamental understanding of how different practices affect the connectivity or lack thereof of governing transport processes and resulting material fluxes across different landscape compartments within the hillslope-channel continuum of IMLs. However, there are no models operating at the event timescale that can accurately predict material flux transport from the hillslope to the catchment scale capturing the spatial and …

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 …

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 …

Determining The Psychosocial Needs Of The Nurses Of Covid-19 Patients, Allison Stevens

ATU Theses and Dissertations 2021 - Present

Nurses are a vital element of the COVID-19 healthcare crisis and have been since the beginning of the COVID-19 response. The professional strain put on nurses included, but is not limited to: changing professional roles, rapidly changing policies and procedures, an influx of patients—particularly of high acuity, and change in workplace morale. However, nurses also had to carry the burdens of living as a member of society, family member, friend, community member, and above all, simply as a person surviving a pandemic themselves. With all of the stressors nurses have endured, it stands to reason that their psychosocial needs have …

Rational Design Of Multifunctional Nanocatalysts For Environmental Remediation And Energy Conversion Technologies, Md Ariful Ahsan

Open Access Theses & Dissertations

The discovery of efficient and sustainable carbon-based nanotechnologies to solve both the scarcity of drinking water and global energy crisis has become a paramount task in the last decades. Owed to the fast population growth and industrialization of the modern society, access to potable water and clean energy technologies is becoming very hard around the globe. Water pollutants have become a serious threat to the environment and ecology because of their toxic nature. Parallelly, the current hydrocarbon-based fuel industries are generating high levels of contamination across the planet, making imperative the development of cleaner energy technologies. In this regard, the …

Goes-16 Level 2 Land Surface Temperature Product-Filling For Cloud Masked Data, Guadalupe Ortega

Open Access Theses & Dissertations

The GOES-16 satellite ground segment team develops different levels of environmental products and makes them readily available to the public. The level 2 Land Surface Temperature (LST) product aims to provide a remote measurement of the Earth’s surface temperature every hour. LST is of fundamental importance to many aspects of the geosciences, for example, to study the Urban Heat Islands (UHI) effect. The product however, does not provide values for pixels where the satellite imager’s view is obstructed by clouds, as determined by a cloud mask intermediate product. The objective of this thesis is to estimate LST in the cloud …

A Human-Embodied Drone For Dexterous Aerial Manipulation, Dongbin Kim

UNLV Theses, Dissertations, Professional Papers, and Capstones

Current drones perform a wide variety of tasks in surveillance, photography, agriculture, package delivery, etc. However, these tasks are performed passively without the use of human interaction. Aerial manipulation shifts this paradigm and implements drones with robotic arms that allow interaction with the environment rather than simply sensing it. For example, in construction, aerial manipulation in conjunction with human interaction could allow operators to perform several tasks, such as hosing decks, drill into surfaces, and sealing cracks via a drone. This integration with drones will henceforth be known as dexterous aerial manipulation.

Our recent work integrated the worker’s experience into …

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 …

Using Iphone Significant Location Data To Improve Air Pollution Exposure Estimation, Elizabeth Eastman

Electronic Theses and Dissertations, 2020-

An accurate estimation of human exposure to ambient air pollution is crucial for air pollution health studies. Time-activity patterns may introduce substantial uncertainties in exposure estimation. As smartphones are becoming increasingly popular and their ownership is becoming ubiquitous in the US. Virtually all smartphones can collect location data, and such data is continuously somewhere. Therefore, it is clear that such stored location data has the potential to be used for characterizing an individual's time-activity patterns for air pollution health studies. However, studies on the accuracy and feasibility of using a smartphone's location data in air pollution exposure estimation are still …

Production Of Protactinium-229 Via Deuteron Irradiation Of Thorium-232, Naser Burahmah

Doctoral Dissertations

²²⁵Ac [Actinium-225] is a promising radionuclide for targeted alpha therapy of cancer. ²²⁹Pa can lead to the production of ²²⁹Th [Thorium-229] and ²²⁵Ac [Actinium-225]. Deuteron bombardment on natural thorium targets has been investigated to measure cross sections of protactinium isotopes. In this work, ²²⁹Pa [Protactinium-229] excitation function was measured via deuteron energies up to 50 MeV [Mega electron volt] of thin thorium foils. The irradiation took place at Lawrence Berkeley National Laboratory’s (LBNL) 88-Inch Cyclotron. The target processing and analysis were performed at Oak Ridge National Laboratory (ORNL). The target consisted of 4 thin foils …

Perceptions Of High Achieving High School Students Regarding The Professionalization Of Teaching And Their Interest In Becoming Teachers, Jonathan Crossley

ATU Theses and Dissertations 2021 - Present

This study was designed to highlight the factors that contribute to high-achieving high school students not deciding to join the teaching profession. There is growing evidence to indicate that the teaching profession is comprised mostly of educators in their first five years in the profession and educators with more than 25 years of teaching experience. Increasing numbers of educators are leaving the profession within their first five years in a classroom. On the other end of the spectrum, as teachers with more than 25 years of experience ultimately retire, the question remains about the viability of the profession for younger …

Supercritical Co2 Recompression Closed Brayton Cycle Analysis, Andres Eduardo Gutierrez Hernandez

Open Access Theses & Dissertations

On this research, the results of an analysis made of a Supercritical Carbon Dioxide (sCO2) Recuperated Closed Brayton Cycle (RCBC) done by performing theorical calculations and comparing it to the results obtained with the use of the software ASPEN Plus will be presented. To demonstrate and determine that this software is a useful tool for modeling the proposed type of cycle, a preliminary comparison was made to verify with previous studies found in literature. A comparison and analysis between the possible working fluids and thermal energy sources was also performed to emphasize the decision of using CO2 as the cycle …

Environmental Justice Issues And Sea Level Rise In Frontline Communties Along The Gulf Coast, Karla Michel Lopez

Open Access Theses & Dissertations

Sea level rise poses a great threat to coastal areas and our way of life. As flooding increases in frequency and intensity across the country, vulnerable populations become a target to its impacts. The U.S. dedicates much research to risk communication and climate change adaptation strategies; however, these coastal areas are home to a large percentage of underserved and underrepresented communities that can be challenging to meaningfully engage. The impacts of short-term sea level rise combined with long-term sea level rise will not only cause flooding, erosion, and intrusion of saltwater into freshwater resources but also increased financial consequences, such …