Physical Sciences and Mathematics Commons^™

Spectroscopic Studies On Silicon And Chalcopyrite Materials For Solar Energy Applications, Amandee Hua

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this dissertation, silicon-based materials for photovoltaics and chalcopyrite-based materials for photoelectrochemical water splitting are investigated using various spectroscopic and microscopic techniques. Although silicon dominates the photovoltaic market, further improvement can be made by using an alternative low temperature passivation approach. Currently, thermally grown SiO2 passivation is commonly used for silicon solar cells. However, this technique requires high processing temperatures (>800 °C), which increases the thermal budget, potentially decreases the bulk quality of Si, and can lead to difficulties in implementing in production lines. Here, a S-based passivation approach is studied that require lower processing temperatures of ~550 °C. …

Applying Instrumental Neutron Activation Analysis To Assess Air Pollution With Spanish Moss As A Bioindicator In The Low Country Of The Savannah River Basin, Christina Jiang

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Savanah River Basin is an area of 9,850 square miles that stretches from the border between South Carolina and Georgia, which empties into the Atlantic Ocean near Savannah, Ga. This area is home to surrounding cities, industrial sites, and the Savanah River Site. It is well documented that traffic, industrial operations, and agriculture contribute to worsening air pollution that needs to be monitored. While Tillandsia usneoides (Spanish moss) has been used in previous studies that prove it to be an effective biomonitor for air pollution and an accumulator of heavy metals, there have been no biomonitoring studies in the …

A Generalized Family Of Exponentiated Composite Distributions With Applications To Insurance And Survival Data, Bowen Liu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The concept of composite distributions was proposed in the early 2000s as a good parametric solution to model the data with heavy tails. Since the concept was proposed, it has been widely used in different areas, such as modeling insurance claim size data, predicting the risk measures in insurance data analysis, fitting survival time data, and modeling precipitation data. While a lot of the composite distributions demonstrated great performances in real applications, many commonly used composite distributions such as the inverse gamma-Pareto (IGP) or exponential-Pareto (EP), did not demonstrate great performances when fitting to several particular data sets. In order …

Algorithmic Approaches To Battery Consolidation In A Smart Grid, Dara Nyknahad

UNLV Theses, Dissertations, Professional Papers, and Capstones

The concept of the battery exchange station (BES) as a part of the battery consolidation system (BCS) has certain criteria that make it a significant player in the better adaptation plan of electric vehicles (EVs) in the grid toward the smart grid. In this dissertation, we study the BES optimization problem as a promising approach for EV adaptation in a smart grid. We introduce the concept of BCS, which focuses on optimizing the incorporation and transaction of all of the components in a smart grid. Accordingly, we address three BES optimization problems in the BCS. In the first problem, we …

Characterization Of Hematite Coated Bedrock Fault Scarps In The Northern Colorado River Extensional Corridor Near Lake Mead, Nevada, Molly E. Pickerel

UNLV Theses, Dissertations, Professional Papers, and Capstones

Fault mirrors are reflective, thin, typically <1 mm thick, fault slip surfaces in exhumed fault zones that can provide a record of thermal, chemical, and rheological changes to fault materials during deformation. This study investigates a series of hematite coated fault mirrors along bedrock fault scarps in Miocene volcanic rocks near Lake Mead, Nevada. The studied faults are located in a structurally complex area that includes NE-SW trending left-lateral strike-slip faults of the Lake Mead fault system, NW-SE right-lateral strike-slip faults of the Las Vegas Shear Zone, and N-S striking extensional faults of the Northern Colorado River Extensional Corridor.New zircon U-Pb ages from fault scarp host rocks 21-BC-03 and 21-BC-05 are and 13.86 ± 0.27 Ma and 12.90 ± 0.31 Ma (2σ standard error), respectively. New apatite (U-Th)/He dates range from 5.64 ± 0.46 Ma to 12.4 ± 0.36 Ma (2σ standard error) and are interpreted to be partially reset after eruption due to reheating. Inverse thermal history modeling in HeFTy of apatite He dates indicates a thermal history of reheating to ~65 °C which is interpreted as shallow burial around ~11 - 5 Ma followed by cooling to the surface, interpreted as exhumation between ~4.5 - 2 Ma. The zircon U-Pb ages, apatite He dates, and inverse thermal history models indicate the fault host rocks were erupted to the surface and stayed within the upper ~2 km of the crust since the Miocene. Nearly vertical fault scarps that host the fault mirror surfaces exhibit two sets of slickenlines, indicating oblique and strike-slip motion, with different orientations indicating that there have been multiple episodes of deformation along the surfaces. Three of the five studied fault scarps have E-W orientations, and one scarp is NW-SE, and one is NE-SW striking. The studied faults are interpreted to have been active during deformation associated with the Lake Mead Fault System and the Las Vegas Valley Shear Zone at 13 – 9 Ma and record both strike slip and oblique slip events in the complex strain field during this time. Micro-nano scale texture and grain morphology analysis of the hematite fault mirror volumes shows extreme strain localization along the fault mirror surface. Some fault mirrors exhibit multiple domains separated by discrete slip surfaces. Comminution and cataclasis appear to be the dominant deformation mechanisms in the fault mirror volume. Hematite textures and morphologies are consistent with observations from other fault systems that are interpreted to record aseismic to sub-seismic slip rates, and relatively low coseismic temperature rise. Fluid injection veins and post-deformation FeO mineralization in fractures are interpreted as evidence of high fluid pressures during slip and fluid circulation postdeformation. The new geochronologic and microstructural data inform on the processes operating along discrete fault surfaces in the shallow crust since the Miocene in the Lake Mead region.

Morphologic Comparisons Of Recrystallized And Neocrystallized Fibrous Amphibole Asbestos: Implications For Corresponding Health Risk Potential, Natalie G. Renkes

UNLV Theses, Dissertations, Professional Papers, and Capstones

The presence of naturally-occurring asbestos (NOA) is increasingly concerning for scientists, health and regulatory agencies, and citizens living in impacted areas. It is commonly believed that fibrous amphibole asbestos can only form through neocrystallization. In southern Nevada, NOA occurs as a result of hydrothermal alteration of granitic rock producing fibrous amphibole both as cross-cutting neocrystallized veins and via recrystallization of original magmatic hornblende crystals. Fibers with a greater aspect ratio are known to have increased toxicity. This study measured the maximum length and average width of both neocrystallized and recrystallized fibers to see if the morphologies were similar. Neocrystallized and …

Mathematical Modeling: Finite Element Analysis And Computations Arising In Fluid Dynamics And Biological Applications, Jorge Reyes

UNLV Theses, Dissertations, Professional Papers, and Capstones

It is often the case when attempting to capture real word phenomena that the resulting mathematical model is too difficult and even not feasible to be solved analytically. As a result, a computational approach is required and there exists many different methods to numerically solve models described by systems of partial differential equations. The Finite Element Method is one of them and it was pursued herein.This dissertation focuses on the finite element analysis and corresponding numerical computations of several different models. The first part consists of a study on two different fluid flow models: the main governing model of fluid …

Stoichiometric Determination Of Hydride Materials At Extreme Conditions, Gregory Alexander Smith

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen was predicted to be a high-temperature superconductor at near-megabar conditions in 1968,[1] but only recently was been experimentally observed.[2] This is due to the extraneous metrological constraint of requiring 5 megabars of pressure to stabilize. A more practical approach for synthesis of high-temperature superconductors has been pro-posed through the use of hydride compounds. Recently, a surge of rare earth hydrides have achieved critical superconducting transition temperatures (T_C ) close to room temperature.[3, 4, 5, 6] However, due to limitations of the necessary instrumentation to achieve megabar pressures, many techniques traditionally used to measure stoichiometry are unavailable.Three works presented in …

High Clearance Collision-Free Paths, Barun Thapa

UNLV Theses, Dissertations, Professional Papers, and Capstones

Path Planning is one of the widely investigated research areas in computational geometry and robotics. Given a set of polygonal obstacles inside a rectangular box, and start & goal points, the path planning problem is to construct a collision-free path connecting the start point to the goal point. We review existing well known algorithms for solving the path planning problem. We propose new approaches for constructing a collision-free path with high clearance from obstacles. The main idea of the proposed algorithm is the appropriate generation free-region nodes which can be processed to construct high clearance paths. Neighbors of free-region nodes …

The Effects Of Habitat Isolation On Fine-Scale Genetic And Geographic Structure Of Populations Of Two Threatened Endemic Insects In Southern Nevada, Pseudocotalpa Giulianii And Icaricia Shasta Charlestonensis, Kristen Tovar

UNLV Theses, Dissertations, Professional Papers, and Capstones

Assessing the role geographic isolation and ecological specialization have on phylogeographic patterns contributes to our understanding of the evolutionary history of a species and the processes that erode genetic diversity. I used mitochondrial and nuclear genomic sequences to assess whether habitat isolation has shaped the fine-scale patterns of present-day genetic structure and diversity in two threatened insect species endemic to southern Nevada. Pseudocotalpa giulianii (Coleoptera; Scarabaeidae) is a dune obligate scarab beetle endemic to only two small, isolated sand dunes in Nye County, Nevada, with a usable habitat of less than 4.2 km sq that is impacted by on-going degradation. …

Analysis And Application Of Finite Element And High-Order Finite Difference Methods For Maxwell’S Equations In Complex Media, Li Zhu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Perfectly Matched Layer (PML) technique is an effective tool introduced by B´erenger [13] to reduce the unbounded wave propagation problem to a bounded domain problem. This dissertation focuses on two different PML models and their applications to wave propagation problems with Maxwell’s equation in complex media. We investigate these models using two popular numerical methods: the Finite Difference Method (FDM) in Chapters 2 and 3, and the Finite Element Method (FEM) in Chapters 4 and 5.In Chapter 2, we focus on analyzing the stability of a PML developed by B’ecache et al. [10] for simulating wave propagation in the …

Storm Surge Risk Assessment In Coastal Communities In The Rio Grande Valley: An Application Of Gis-Based Spatial Multicriteria Decision Analysis With Analytical Hierarchy Process, Dean Kyne

Sociology Faculty Publications

Cameron County, which is located in the Rio Grande Valley, maintains records of storm surges associated with noticeable property damage, fatalities, and injuries. This study investigates storm surge inundation risk in Cameron County using storm surge hazard datasets from the National Oceanic and Atmospheric Administration, along with American Community Survey 2019 block group datasets. Using a GIS-based spatial multicriteria decision analysis with an analytical hierarchy process method, the study estimates that storm surge water levels could be above 6.1 m (20 ft) in category 4 and 5 hurricane events, whereas about 37% of the county’s population (159,659 people) could be …

Methods For Preparing And Characterizing Granular Materials For Electron Yield Measurements, Tom Keaton

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

This work presents a systematic study on sample preparation methods and accuracy of electron yield (EY) measurements of highly insulating, granular materials. EY measurements of highly insulating materials, especially those with high EY, are challenging due to the effects of sample charging even for very low fluence electron probe beams. EY measurements of particulates are complicated by: (i) roughness effects from particulate size, shape, coverage, and compactness; (ii) particle adhesion; (iii) substrate contributions; and (iv) electrostatic repulsion and potential barriers from charged particles and substrates. Numerous methods were explored to rigidly affix particles on conducting substrates at varying coverages for …

Multivariate Econometric Regression Of Factors That Determine Form Of Disposition Of Human Remains Using Archival Death Certificates, Salt Lake County, Utah, Delphine T. Feigenbaum

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

This project considers the inescapable and burgeoning issues concerning the long-term allocation of scarce natural resources between the living and the deceased. America’s population growth will demand more space and maintenance resources used for disposition. To meet the forthcoming exigencies, economic planners need to address natural resource availability for future generations while incorporating sustainable and innovative technologies to prohibit environmental injustice.

The goals are to answer the following questions: How do demographical variables, age and sex influence the choice of disposition? How do cause of death variables influence the choice of disposition? I also evaluate the hypothesis that the average …

An Integrated Experimental And Modeling Approach To Design Rotating Algae Biofilm Reactors (Rabrs) Via Optimizing Algae Biofilm Productivity, Nutrient Recovery, And Energy Efficiency, Gerald Benjamin Jones

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Microalgae biofilms have been demonstrated to recover nutrients from wastewater and serve as biomass feedstock for bioproducts. However, there is a need to develop a platform to quantitatively describe microalgae biofilm production, which can provide guidance and insights for improving biomass areal productivity and nutrient uptake efficiency. This paper proposes a unified experimental and theoretical framework to investigate algae biofilm growth on a rotating algae biofilm reactor (RABR). The experimental laboratory setups are used to conduct controlled experiments on testing environmental and operational factors for RABRs. We propose a differential-integral equation-based mathematical model for microalgae biofilm cultivation guided by laboratory …

Historic Downtown Streetscape Plan Price City, Utah, Patricia Beckert

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The idea of a small-town Main Street has profound meaning within the American culture that has prevailed for the past two centuries. Historically, Main Street serves as the beating heart of a community, a place where economic, social, cultural, and civic activities are centered (Francaviglia, 1996; Main Street America, n.d.). Since the beginning of the 19th century, many factors have led to the decline of Main Streets, and despite a variety of efforts from different stakeholders, that decline has only intensified in recent decades (Isenberg, 2008; Orvell, 2014 Howard, 2015). In 1980, after a three-year project conducted by the National …

Design And Synthesis Of Novel Peptide-Metal Organic Frameworks, Moustafa Mahmoud Abdel Wahid Hamaad

Theses and Dissertations

Metal-organic frameworks (MOFs) are a class of crystalline porous materials with extended network structures formed through the reticular assembly of inorganic and organic molecular building blocks through strong coordination bonds. Compared to other porous materials, MOFs offer a high degree of structural diversity as their shape and pore size as well as functionality can tuned by the precise selection and design of their metal centers and organic struts. Due to their high surface areas, pore volumes, and the possibility of introduction of a myriad of chemical functionalities in their structures, MOFs have gained popularity for applications in many fields such …

Anti-Doping Crisis In Sports, What's Next? Ion Mobility-Mass Spectrometry For The Study Of Anabolic Androgenic Steroids, Diana Constanza Velosa

Theses and Dissertations

The main objective of this work is to augment both qualitative and quantitative measures of anabolic androgenic steroids (AAS) with ion mobility-mass spectrometry (IM-MS), laying the foundation for implementation into analytical drug testing laboratories. AAS testing requires high sensitivity and specificity. IM-MS is presented as an emerging technology workflow capable of targeted quantification of AAS and structural elucidation for potential unknowns, allowing ions to be separated and characterized based on their rotationally averaged collision cross section (CCS). Chapter 1 provides a background of the basic principles of IMS and the different types of analytical methods used for doping analysis currently …

Towards Privacy-Preserving Social Media Networks: Protecting The Facial Privacy Of Images Uploaded On Social Media, Ahsi Lo

Theses and Dissertations

Since the 2000s, social media has allowed individuals the ability to communicate online. As the popularity of social media increased, the sharing of information such as pictures increased as well. Recently, there have been privacy concerns about the information shared online such as cases where third parties were able to gain access to users’ information without being given explicit access through scraping or other means. When user images are scraped from social media, there is a risk that these individuals can be identified o✏ine. Bystanders, who may be captured in images also run this risk of identification. This research investigates …

Assessing The Effect Of Atmospheric Turbulence On Long-Range Face Recognition Accuracy, Muskan Jain

Theses and Dissertations

Recent investigations have demonstrated that it might be challenging to identify faces in the images taken using a long-distance camera. A face seems blurry in these images because of the presence of atmospheric turbulence. To examine how atmospheric turbulence impacts face biometrics, we establish a simulated environment that exhibits different degrees of turbulence. We employed the Rytov Variance, which relies on the distance and refractive index, C2 n, to get various turbulence levels. We used the LRFID dataset to carry out the study, which is a collection of photos and videos taken in the field and in a controlled setting. …

Monte-Carlo Modeling Of Bidirectional Reflectance In Shallow Turbid Water, Tyler Anthony Rotkiske

Theses and Dissertations

The ability to model surface and bottom boundary layers using water column information in shallow waters is mathematically approached using a Monte-Carlo model. The hyperspectral Monte-Carlo model used in this research was previously developed and analytically validated. This mathematical model tracks photons in 3-dimensional space and includes the effects of small gravity waves on the water surface, the bottom reflectance, and constituents within the water column. This type of modeling uses a probabilistic approach and is the only method used to calculate shape factors and mean cosines in a water column and then verified using hyperspectral remote sensing reflectance measurements. …

Nonlinear Mathematical Transformations For Improved Image And Signal Recovery Using Artificial Neural Network, Haoran Chang

Theses and Dissertations

Medical imaging plays a vital role in modern healthcare, enabling clinicians to diagnose and treat a range of conditions. However, image acquisition and processing can be challenging because they can often be hindered by motion blurring, leading to inaccurate results. To address that, this dissertation proposes a novel approach based on nonlinear mathematical transformations and artificial neural networks (ANN). The dissertation begins with an introduction to Nuclear Medicine and the problem of motion blur in image reconstruction. A background on Medical Imaging techniques, including the Radon transform and Image Reconstruction methods such as Filtered Back Projection and Iterative Reconstruction methods …

Towards Explainable Ai: Predicting Linear And Nonlinear Feature Relations Of Datasets, Nimmy Chhaganbhai Patel

Theses and Dissertations

Artificial Intelligence (AI) makes critical decisions in an opaque way without explaining the reasoning behind them. Decision support systems are often built as black boxes. This has generated interest in Explainable AI (XAI), an area of research that explains AI algorithms and provides more insight into their internal decision-making process. Advancements in XAI have enhanced machine learning (ML) models’ interpretability, explainability, and transparency. Additionally, there has been speculation on whether it is possible to predict the type of dataset used in the model by analyzing the results. In this research, we proposed a methodology for determining the linearity or non-linearity …

Sprout: Using A Garden Metaphor To Visualize And Support Customizable And Collaborative Health Tracking, Pape Sow Traoré

Dartmouth College Master’s Theses

Self-tracking tools have become increasingly popular, especially with the advent of wearable technology and smartphone applications. However, traditional tracking tools often display data in a quantitative format that can be overwhelming and cause users to abandon their tracking efforts. Additionally, these tools typically provide a generic user experience and are designed from a single-user perspective, lacking external support. To overcome these limitations, we develop Sprout, a mobile data-tracking application that offers a more qualitative, customizable, and collaborative experience for health monitoring and management. Sprout uses a garden metaphor to visually represent health information and allows users to tailor their …

Correlation Between Fire And Preservation In The Pacific Northwest And Most Cost-Efficient Mitigation Tactics, Liam Doherty-Herwitz

Department of Environmental Studies: Undergraduate Student Theses

This study was conducted entirely online with occasional help from advisors and editors on zoom meetings. I completed the research in Lincoln, Nebraska. A meta analysis of online data has been conducted to form the answers to my hypotheses and research questions. I used specific keywords and phrases in research databases, and search engines such as google scholar to point me towards the answers I was looking for. The keywords and phrases were split up into four different categories which are mitigation techniques, ecosystems, fire severity: PNW, and fire season: PNW. The reason the topics land preservation and fire science …

Recycling Attitudes And Behaviors Toward Single-Use Plastics At The University Of Nebraska–Lincoln, Jadyn Chasek

Department of Environmental Studies: Undergraduate Student Theses

Today, single-use plastics pose an issue in the world with pollution from improper disposal as well as from the manufacturing of single-use plastic products. There is a need for change, plastic products have begun to consume the planet and harm life on Earth. Many people look to college universities for an opportunity to change issues such as the overconsumption of single-use plastics. A college campus is the perfect environment to study what changes can be made to fix an issue as well as how to implement those changes. This study was conducted at the University of Nebraska-Lincoln, where the undergraduate …

Amazon Deforestation And Its Effects On Local Climate, Andrew Baker

Department of Environmental Studies: Undergraduate Student Theses

The Amazon has been faced with extensive deforestation beginning in the 1960’s mainly for the purpose of cattle ranching and agriculture, as well as logging and mining making up smaller but noticeable portions. This rainforest is a place rich in its biodiversity of plants and animals, and until recently it was also one of the planet’s largest natural carbon sinks. This is important to help offset anthropogenic carbon emissions that are accelerating climate change, but because of the land use changes it has been subjected to, it has become another source of carbon release. This study aims to determine what …

Gender And Environmental Sustainability: A Cross-National Analysis On Political Representation Of Women And Subsequent State Sustainability, Erin O'Sullivan

Department of Environmental Studies: Undergraduate Student Theses

The literature focusing on the relationship between gender and environmental sustainability is vast. Research has focused on how gender relates to pro-sustainable behavior but fails to analyze this beyond individual action. Research has also found positive correlations between women’s representation at a state’s political level and different factors of state sustainability. However, literature has fallen short on analyzing if there is a causal effect between these factors. This study aimed to fill this gap in the literature and analyzes how the ratio of women in parliament in a state affects the state’s environmental sustainability. Although the results showed no statistically …

Examining The Psychology And Human Behavior Of Sustainable Living: The Impact Of Socioeconomic Status On Climate Change Education, Samantha Nielsen

Department of Environmental Studies: Undergraduate Student Theses

Climate change education has become increasingly important as the world faces the challenges of a rapidly changing environment. However, not all individuals have equal access to this education, and socioeconomic status has been identified as a barrier to climate change knowledge. This thesis explores the impact of socioeconomic status on climate change education through a survey-based approach, using the Nebraska Annual Social Indicators Survey to investigate the relationship between income and degree of education with climate change concern and community interaction. The study finds a significant correlation between higher levels of education and climate change concern, as well as greater …

Impact Of The Covid-19 Pandemic On Nebraska State Park Visitation, Bailey Mullins

Department of Environmental Studies: Undergraduate Student Theses

The Covid-19 virus was declared a pandemic on March 11, 2020 by the World Health Organization. Since then the outdoor recreation habits of the general public have changed due to the constraints and risks of the virus. The first case of Covid-19 in Nebraska was reported in March of 2020. One of the most popular places for recreation in the state of Nebraska is to visit our state parks and recreation areas. The purpose of this research is to determine how the Covid-19 pandemic has impacted visitation at Nebraska state parks and recreation areas. To do this, the Nebraska Game …