Physical Sciences and Mathematics Commons^™

Design And Preliminary Evaluation Of A Supercritical Carbon Dioxide Brayton Cycle For Solar Dish Concentrator Clean Energy Production, Danielle Nobles-Lookingbill

UNLV Theses, Dissertations, Professional Papers, and Capstones

As we move toward energy independence and more ambitious clean energy goals, solar energy research must push the efficiency limits of traditional energy generation systems. Increases in efficiency can be achieved by increasing the hot temperature of the power cycle. Recent research demonstrates the potential for increased efficiency and a vastly smaller component size when supercritical carbon dioxide Brayton power cycles are used. Concentrated solar and nuclear heat sources are capable of achieving the high working fluid temperatures needed for significant efficiency gains. This NSF EPSCoR funded, experimental research system is designed to exploit the uniquely immense solar irradiance of …

Employee Perceptions Of Organizational Corporate Responsibility And Their Effect On Employee Organizational Commitment, Lisa R. Davis

UNLV Theses, Dissertations, Professional Papers, and Capstones

The debate over whether organizations play a part in society beyond economic profit has been a major focus of research in corporate social responsibility (CSR). These debates have been mainly looked at from the macro (societal) or the meso (institutional) level. Very little research has been done on the role of the firm and looking at CSR from the micro (individual) level. Questions regarding the role of work for employees, securing economic benefits or making a difference in the world, would vary greatly depending on the individual and the importance they place on these areas in their own lives. Scholars …

Studies Of Inner-Shell Chemistry Of Mercury Based Compounds At Extreme Conditions, Sarah Schyck

UNLV Theses, Dissertations, Professional Papers, and Capstones

It has been theoretically predicted that when mercury difluoride (HgF2) is pressurized to above 50 GPa in the presence of molecular fluorine, it will most likely transform into mercury tetrafluoride (HgF4), thus mercury will behave as a transition element at high pressure. However, there is no experimental evidence verifying this prediction yet. To begin with, the crystalline properties of pure HgF2 at high pressure were not experimentally established. In this thesis, the high pressure structural properties of HgF2 are investigated by means of synchrotron X-ray powder diffraction. Our results reveal that the predicted, ambient cubic structure of HgF2 with the …

Application Of Machine Learning Techniques In Credit Card Fraud Detection, Ronish Shakya

UNLV Theses, Dissertations, Professional Papers, and Capstones

Credit card fraud is an ever-growing problem in today’s financial market. There has been a rapid increase in the rate of fraudulent activities in recent years causing a substantial financial loss to many organizations, companies, and government agencies. The numbers are expected to increase in the future, because of which, many researchers in this field have focused on detecting fraudulent behaviors early using advanced machine learning techniques. However, the credit card fraud detection is not a straightforward task mainly because of two reasons: (i) the fraudulent behaviors usually differ for each attempt and (ii) the dataset is highly imbalanced, i.e., …

Bayesian Model Comparisons In Planetary Science, John Henry Boisvert

UNLV Theses, Dissertations, Professional Papers, and Capstones

Model comparison in the modern era allows us to use statistical methods that were previously difficult with older machines. I present a state-of-the-art model comparison code that uses modern Bayesian statistics to measure the Bayes factor between two competing models. The Bayes factor is the ratio of the probability of the data given one model to the probability of the data given another model. My code was used to compare models in five problems in planetary science. The first three pertain to radial velocity exoplanet data. There is a degeneracy in the radial velocity exoplanet signal between a single planet …

Combinatorial Ant Optimization And The Flowshop Problem, Tasmin Chowdhury

UNLV Theses, Dissertations, Professional Papers, and Capstones

Researchers have developed efficient techniques, meta-heuristics to solve many Combinatorial Optimization (CO) problems, e.g., Flow shop Scheduling Problem, Travelling Salesman Problem (TSP) since the early 60s of the last century. Ant Colony Optimization (ACO) and its variants were introduced by Dorigo et al. [DBS06] in the early 1990s which is a technique to solve CO problems. In this thesis, we used the ACO technique to find solutions to the classic Flow shop Scheduling Problem and proposed a novel method for solution improvement. Our solution is composed of two phases; in the first phase, we solved TSP using ACO technique which …

Efficient And Practical Composition Of Lock-Free Data Structures, Neha Bajracharya

UNLV Theses, Dissertations, Professional Papers, and Capstones

A concurrent data object is lock-free if it guarantees that at least one, among all concurrent operations, finishes after a finite number of steps. In other words, a lock free technique guarantees that some thread always makes progress. Lock-free data objects offer several advantages over their blocking counterparts, such as being immune to deadlocks and priority inversion, and typically provide high scalability and performance, especially in shared memory multiprocessor architectures.

Composition of data structures is a powerful approach to combine simple data structures to create more complex ones. It works as a building block for many advanced useful data structures. …

Influencing Hawai‘I Hotel Patrons To Use Reef-Safe Sunscreens, Rochelle Good

UNLV Theses, Dissertations, Professional Papers, and Capstones

The health of Hawaiian coral reefs is threatened by pollution from common sunscreen ingredients such as oxybenzone. Hawai‘i hotel patrons using sunscreens with harmful ingredients contaminate coral reefs when these products wash off while swimming or bathing. Reef-safe sunscreens are alternative sunscreens that provide effective sun protection while averting damage to coral reefs. The purpose of this research was to determine the dominant factors leading to the pro-environmental behavior of using reef-safe sunscreen and identify practices that Hawai‘i hotel operators could implement to influence patrons to engage in this behavior. This research applied an integrative conceptual framework to model pro-environmental …

Effects Of Ambient Air Pollution On Asthma-Related Emergency Department Visits Within The Las Vegas Metropolitan Area, Loiren E. Monardes

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of this research was to evaluate the risk for asthma-related Emergency Department visits and their association with ambient air pollution within the Las Vegas metropolitan area. All data were aggregated by date and ZIP Code. The association was analyzed by applying the distributed lag non-linear model in an attempt to identify elevated concentrations of specific air pollutants

as triggers and their delayed effects (lag days). Relative Risk (RR) and 95% confidence intervals were produced, while adjusting for socioeconomic status. This ecological population-based study analyzed daily asthma counts of Emergency Department visits from January 1st, 2009 to December 31st, …

Design, Layout, And Testing Of Sige Apds Fabricated In A Bicmos Process, Dane Laurence Gentry

UNLV Theses, Dissertations, Professional Papers, and Capstones

This Thesis is concerned with the design, layout, and testing of avalanche photodiodes (APDs). APDs are a type of photodetector and, thus, convert light signals into electrical signals (current or voltage). APDs can be fabricated using silicon (Si). In this Thesis, however, three integrated circuit (IC) chips containing various silicon-germanium (SiGe) APDs with different sizes, structures, and geometries were designed, laid out, and fabricated using the Austriamicrosystems (AMS) 0.35μm SiGe BiCMOS (S35) process. This was done in order to compare SiGe APDs to Si only APDs and investigate the hypothesis that SiGe APDs are capable of detecting longer wavelengths than …

Optimization Of Useful Hard X-Ray Photochemistry, David Lewis Goldberger

UNLV Theses, Dissertations, Professional Papers, and Capstones

X-ray induced damage is generally considered a nuisance, but in the field of Useful Hard X-ray Photochemistry we harness the highly ionizing and penetrating properties of hard X-rays (> 7 keV) to initiate novel photochemical decomposition and synthesis at ambient and extreme conditions. Preliminary experiments suggest that the energy of irradiating photons and the sample pressure play roles in determining the nature of X-ray induced damage. Here, we present the X-ray energy dependence of damage induced in strontium oxalate, strontium nitrate, and barium nitrate, as well as the pressure dependence of X-ray induced damage of strontium oxalate. Our results indicate …

Scheduling Two Machines With Dissimilar Costs, Madhurupa Moitra

UNLV Theses, Dissertations, Professional Papers, and Capstones

We consider two devices, which has states ON and OFF. In the ON state, the devices use their full power whereas in the OFF state the devices consume no energy but a constant cost is associated with switching back to ON. Such two devices are configured with different run and power-up costs on which a sequence of jobs must be processed. The object is to minimize the cost. Such systems are widely used to conserve energy, for example, to speed scale CPUs, to control data centers, or to manage renewable energy.

The problems are studied in the framework of online …

Petrogenesis Of Enriched And Intermediate Poikilitic Shergottites: From Magmatic Source To Emplacement, Rachel Rahib

UNLV Theses, Dissertations, Professional Papers, and Capstones

Poikilitic shergottites, making up >20% of martian meteorites, likely represent a significant composition of the martian crust, as intrusive gabbroic rocks. To further constrain petrogenetic relationships amongst enriched and intermediate poikilitic shergottites, we utilize bulk rock trace element compositions, mineral major element compositions, phosphorus maps of olivine grains, oxygen fugacity (ƒO2) values, subsolidus equilibration temperatures, and quantitative textural analyses, of the most comprehensive suite of poikilitic shergottites yet (11 samples), including three newly recovered samples (Northwest Africa [NWA] 11065, NWA 11043, NWA 10961). Although petrographically light rare earth element (LREE) enriched and intermediate poikilitic shergottites are similar, distinct LREE abundances …

Human Thermal Comfort In Transition Space, Asawari Anil Pawar

UNLV Theses, Dissertations, Professional Papers, and Capstones

ABSTRACT

HUMAN THERMAL COMFORT IN TRANSITION SPACES

Objective: To evaluate and identify the relationship between personal factors and the climatic conditions that influence the human thermal comfort in transition spaces and suggest solutions for adaptation of the built environment, that would encourage active and healthy living in the tourist as well as local community.

Background:

By 2050, there is a prediction that two-thirds of the world population will be living in urban areas, which would add more than 2.5 billion people living in cities (Melnikov et al., 2017). Since Las Vegas is one of the fastest growing cities in Nevada, …

Mechanisms For The Incorporation And Distribution Of Radionuclides In Near-Surface Fallout, Marc Alan Fitzgerald

UNLV Theses, Dissertations, Professional Papers, and Capstones

Fallout is the radioactive glass formed from a mixture of vaporized anthropogenic materials with proximate environmental material. These glassy byproducts constitute a compositional record of environmental materials such as soil and vapor precursors that are responsible for chemical heterogeneity in the glasses. The work of this dissertation is to untangle these different sources of compositional heterogeneity, distinguishing low-abundance vaporized anthropogenic-rich material from natural compositions, in order examine soil behavior and chemical evolution during fallout formation. Unfortunately, mixing convolutes the multivariate elemental relationships in these melts due to overlapping element abundances that might distinguish different source materials and chemical behaviors, making …

Prokaryotic Diversity And Aqueous Geochemistry Of Subsurface Environments Of The Death Valley Regional Flow System, Joshua David Sackett

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation summarizes over four years of effort towards the completion of a Ph.D. in Biological Sciences. The work presented in this document covers a broad range of topics, but a central unifying theme is prokaryotic life in the continental subsurface. The work presented in each chapter relied heavily on cultivation-independent methods for assessing prokaryotic communities, including prokaryotic community structure reconstruction from high-throughput sequencing of 16S rRNA gene libraries and single-cell genome analysis of novel uncultivated bacteria.

Chapter 2 examines the aqueous geochemistry and prokaryotic diversity of Devils Hole, a cavernous limnocrene and sole natural habitat for the critically endangered …

The Use Of Chemical Element Fingerprints To Investigate The Transformation Of Lake Sediments To Land Soils In Drying Lakes: A Case Study At Lake Mead, Nevada, Ji Hye Park

UNLV Theses, Dissertations, Professional Papers, and Capstones

Drying lakes are a worldwide catastrophe. The goals of this dissertation research were (1) to investigate whether chemical fingerprints of lake sediments, and nearby land soils, could be established by the analysis of 44 chemical elements, moisture content, Eh, pH, and leachable anions and if so, (2) whether the fingerprints could help explain the process of physical and chemical changes in the lake sediments as they became soils when the lake's water level fell and the anoxic sediments were exposed to the air and weather.

Lake Mead was chosen to model drying lakes because its water level has fallen over …

Estimation Of The Parameters In A Spatial Regressive-Autoregressive Model Using Ord's Eigenvalue Method, Sajib Mahmud Mahmud Tonmoy

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis, we study one of Ord's (1975) global spatial regression models.

Ord considered spatial regressive-autoregressive models to describe the interaction

between location and a response variable in the presence of several covariates. He also

developed a practical estimation method for the parameters of this regression model

using the eigenvalues of a weight matrix that captures the contiguity of locations.

We review the theoretical aspects of his estimation method and implement it in the

statistical package R.

We also implement Ord's methods on the Columbus, Ohio, crime data set from the

year 1980, which involves the crime rate of …

Examining Environmental Hazards In Rental Homes And Habitability Laws In Clark County, Nevada, Jorge Luis Bertran

UNLV Theses, Dissertations, Professional Papers, and Capstones

It is well established that home conditions are linked to the health outcomes of occupants. There are over 880,000 housing units in Clark County, Nevada; nearly half of those are renter-occupied units (ROUs). Currently, there is limited research on the characteristics of environmental hazards found in Clark County ROUs and the strength of habitability statutes created to protect tenants from substandard housing. Understanding how renters in Clark County are affected by environmental hazards in ROUs and the processes by which landlords and tenants resolve grievances related to those hazards would benefit public health. It would enhance the ability to quickly …

Uas-Based Object Tracking Via Deep Learning, Marc Dinh

UNLV Theses, Dissertations, Professional Papers, and Capstones

Tracking is the task of identifying an object of interest and detect its position over time, and has numerous applications like surveillance, security and traffic control. In present times, unmanned aerial vehicles (UAV) have been more and more common which provides us with a new and less explored domain, with an ideal vantage point for surveillance and monitoring applications.. Aerial tracking is a particularly challenging task as it introduces new environmental variables such as rapid motion in 3D space. We propose a new deep learned tracker architecture catered to aerial tracking.

First, a study of six state-of-the-art deep learned trackers …

Mitigating Accumulation Of Aeolian Dust Particles On Solar Power Generator Panels Without Water, Sanjana Das

UNLV Theses, Dissertations, Professional Papers, and Capstones

Accumulation of dust on solar panels poses a serious problem as it can significantly reduce light absorption and electrical energy output. Several factors affect the dust accumulation such as location, dust properties, wind velocity, system orientation, ambient temperature, humidity, and panel surface properties. Experimental and theoretical studies show that short circuit current and maximum power output of photovoltaic panels reduce approximately linearly with dust concentration. Incidentally, the locations with higher solar energy concentrations are also arid or semi-arid regions with higher dust concentrations. In order to avoid loss in power output, most PV installations perform periodic panel cleaning with water. …

Performance Analysis Of Blockchain Platforms, Pradip Singh Maharjan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Blockchain technologies have drawn massive attention to the world these past few years mostly because of the burst of cryptocurrencies like Bitcoin, Etherium, Ripple and many others. A Blockchain, also known as distributed ledger technology, has demonstrated huge potential in saving time and costs. This open-source technology which generates a decentralized public ledger of transactions is widely appreciated for ensuring a high level of privacy through encryption and thus sharing the transaction details only amongst the participants involved in the transactions. The Blockchain is used not only for cryptocurrency but also by various companies to meet their business ends, such …

Testing An Improved Method For Estimating The Unsaturated Hydraulic Conductivity Of Moderately Dry Soils, Sara Gedo

UNLV Theses, Dissertations, Professional Papers, and Capstones

Prediction of water movement in the vadose zone requires knowledge of either the unsaturated hydraulic conductivity, K(θ), or the hydraulic diffusivity, D(θ), of the soil as a function of the moisture content. However, both K(θ) and D(θ) are difficult to obtain for moderately dry soils because the tests are time consuming and expensive. In order to address this issue, Globus and Gee (1995) developed a “heat pipe” method that allowed for the direct estimation of D(θ) and K(θ) for moderately dry soils on relatively short time scales. They proposed that exposing a sealed horizontal soil column to a steady thermal …

Dissolution Rates Of Allophane, Fe-Allophane, And Hisingerite And Implications For Aqueous Alteration On Mars And In Potential Returned Martian Samples, S. J. Ralston

UNLV Theses, Dissertations, Professional Papers, and Capstones

Recent measurements from Mars document X-ray amorphous/nano-crystalline materials in multiple locations across the planet. However, despite their prevalence, little is known about these materials or what their presence implies for the history of Mars. The amorphous component of the martian soil in Gale Crater has an X-ray diffraction pattern that can be partially fit with allophane (approximately Al2O3•(SiO2)1.3-2•(H2O)2.5-3), as well as low-temperature water release consistent with allophane. The chemical data from Gale Crater suggest that other silicate phases similar to allophane, such as Fe-substituted allophane (here, approximately (Fe2O3)0.01(Al2O3)0.99(SiO2)2•3H2O) and hisingerite (approximately Fe3+2Si2O5(OH)4•(H2O)), may also be present. In order to investigate …

Conformal Mapping Improvement Of The Boundary Element Method Solution For Underground Water Flow In A Domain With A Very Singular Boundary, Megan Romero

UNLV Theses, Dissertations, Professional Papers, and Capstones

Numerical solutions using a Boundary Element Method (BEM) for a confined flow in a very singular finite domain are developed. Typically, in scientific journal publications, authors avoid domains with many and more malignant singularities due to the extremely big and difficult to estimate errors in the numerical calculations. Using exact Conformal Mapping solutions for simplified domains with the same singularity as in the original domain, this problem can be solved numerically with improvements introduced by Conformal Mapping solutions. Firstly, to experiment with improving the BEM solution by Conformal Mapping, a domain inside a rectangle is considered. The exact solution inside …

Force Multiplier Calculations For X-Ray Binaries And Active Galactic Nuclei, Randall Cody Dannen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Motivated by the work done to explore the winds from hot stars (Lamers & Cassinelli 1999), we develop a method for self consistently calculating force multipliers for Type 1 and Type 2 active galactic nuclei (AGN), soft and hard start X-ray binaries (XRBs) spectral energy distributions (SEDs). We find that the ampflication to the radiation force can be as large as 100 even when the gas is highly ionized due to Fe and O ions. We discuss future efforts to incorporate these findings in magnetohydrodynamic simulations.

Application Of Machine Learning In Cancer Research, Mandana Bozorgi

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation revisits the problem of five-year survivability predictions for breast cancer using machine learning tools. This work is distinguishable from the past experiments based on the size of the training data, the unbalanced distribution of data in minority and majority classes, and modified data cleaning procedures. These experiments are also based on the principles of TIDY data and reproducible research. In order to fine-tune the predictions, a set of experiments were run using naive Bayes, decision trees, and logistic regression.

Of particular interest were strategies to improve the recall level for the minority class, as the cost of misclassification …

Crystallographic Exploration Of Fundamental Technetium Species At Nonambient Conditions, Daniel S. Mast

UNLV Theses, Dissertations, Professional Papers, and Capstones

The study of mater under extreme conditions has yielded fascinating insight into the physical and chemical nature of materials that under more modest conditions are considered mundane but have quite unusual properties when under pressure. Examples of this are the lightest of elements found in the first two rows and in the heaviest elements of the lanthanide and actinide series. Pure elements, though the simplest possible chemical systems, have proven to be among the most complex and interesting. Technetium metal is a simple HCP transition metal that, due to its half-filled d-shell, has a rich chemistry and an important place …

Study Of Blockchain-As-A-Service Systems With A Case Study Of Hyperledger Fabric Implementation On Kubernetes, Aniket Jalinder Yewale

UNLV Theses, Dissertations, Professional Papers, and Capstones

Blockchain is a shared, immutable, decentralized ledger to record the transaction history. Blockchain technology has changed the world, changed the way we do the business. It has transformed the commerce across every industry, which may be supply chain, IoT, financial services, banking, healthcare, agriculture and many more. It had introduced a new way of transactional applications that bring trust, security, transparency and accountability.

To develop any blockchain use case, the main task is to develop an environment for creating and deploying the application. In our case, we created an environment on IBM Cloud Kubernetes service using Kubernetes, a container orchestration …

A Dramatistic Analysis Of Nevada's Controversy Over Solar Net Metering Incentive Policies, Robert S. Burgy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Utilizing a dramatistic rhetorical lens (Burke, 1945), this project examines Nevada’s 2015-2017 public controversy to decide whether or not to implement solar net metering incentives. By examining communication surrounding The Public Utility Commission of Nevada (PUCN), NV Energy, and SolarCity, this thesis analyzes the underlying social orientations contained within the controversy’s discourse. This thesis examines how the environment was left out of solar energy discourse in favor of economic reasoning. Nevada’s solar controversy is an important component of humanity’s unending conversation about our relationship to the environment and an important case study to develop our understanding of public controversy.