Physical Sciences and Mathematics Commons^™

High Pressure X-~Ray Absorption Spectroscopy Studies Of Heavy-~Fermion Cerium And Uranium Compounds, Daniel Antonio

UNLV Theses, Dissertations, Professional Papers, and Capstones

Investigations into f- electron heavy-fermion materials have revealed a wide range of novel behavior. Hydrostatic pressure is a valuable "clean" non-thermal parameter that can be used to systematically study them by tuning their ground state properties. The rare earth compound CeCu2Ge2 shows an unusual two-domed region of unconventional superconductivity under pressure, similar to its isostructural counterpart CeCu2Si2. While the lower pressure dome at about 10 GPa is caused by a magnetic quantum critical point (QCP), the higher one at about 16 GPa is less well understood. Previous structural measurements have indicated that it may be caused by critical valence fluctuations, …

Chemical And Electronic Structure Of Surfaces And Interfaces In Cadmium Telluride Based Photovoltaic Devices, Douglas Arthur Duncan

UNLV Theses, Dissertations, Professional Papers, and Capstones

The surface and interface properties are of the upmost importance in the understanding, optimization, and application for photovoltaic devices. Often the chemical, electronic, and morphological properties of the films are empirically optimized, however when progress slows, a fundamental understanding of these properties can lead to breakthroughs. In this work, surfaces and interfaces of solar cell-relevant films are probed with a repertoire of X-ray analytical and microanalysis techniques including X-ray photoelectron (XPS), X-ray excited Auger electron (XAES), X-ray emission (XES) spectroscopies, and atomic force (AFM) and scanning electron (SEM) microscopies.

Silicon-based devices currently dominate the solar market, which is rather inflexible …

Optimization Of The Development Process For Air Sampling Filter Standards, Rajah Marie Mena

UNLV Theses, Dissertations, Professional Papers, and Capstones

Air monitoring is an important analysis technique in health physics. However, creating standards which can be used to calibrate detectors used in the analysis of the filters deployed for air monitoring can be challenging. The activity of a standard should be well understood, this includes understanding how the location within the filter affects the final surface emission rate. The purpose of this research is to determine the parameters which most affect uncertainty in an air filter standard and optimize these parameters such that calibrations made with them most accurately reflect the true activity contained inside. A deposition pattern was chosen …

Ecosystem Response To Recent Climate Change In Alpine Environments, Patrick Shawn Sawyer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Recent variations in meteorological conditions indicate the earth’s climate is changing in ways that can impact delicate ecological balances in sensitive regions. These impacts threaten the essential services provided by such ecosystems. Determining how climate changes are affecting the biosphere is essential to adapt and mitigate harmful consequences. In order to mitigate the negative effects of climate change and adapt to shifting ecological resource constraints, it is imperative to locate such changes and determine vulnerability of ecological resources to changing environmental conditions.

Identifying climate driven ecological changes faces numerous challenges given the reliance on vegetation indices as the primary measure …

Dissolution Of Nontronite In Low Water Activity Brines And Implications For The Aqueous History Of Mars, Michael Henry Steiner

UNLV Theses, Dissertations, Professional Papers, and Capstones

Water is essential to life on Earth and is likely to play a role in determining the habitability of other planets. Pure liquid water is not stable on the surface of Mars but brines can temporarily remain liquid, and increasing evidence suggests the presence of recent liquid water, including brines, on Mars. Brines can host life at temperatures as low as -30 ºC and some organisms can live at activities of water as low as 0.61. Therefore, if brines have been present on Mars, they may act as habitable environments.

The Fe-rich smectite nontronite, (CaO0.5,Na)0.3 Fe3+2(Si,Al)4O10(OH)2·nH2O, has been detected on …

The Visual Framing Of The Three Cycles Of Climate Control In The New York Times 1851 To Present, Jason Lee Thompson

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research explored the visual framing of climate control in The New York Times through three cycles of media history. Although no peer-reviewed study has explored this specific topic, a wealth of prior communication articles on both the visual and textual aspects of climate change and geoengineering in the media was mined in order to discover the frames present. Once the visual frames of climate control (war, fix, people, and impacts) were revealed a content analysis was conducted in order to see which frame elements were most and least frequent considering the images of climate control. When combining all three …

Architectural Form, Orientation, And Energy For Residential Design In The Southern Nevada Region., Ludwing Vaca

UNLV Theses, Dissertations, Professional Papers, and Capstones

With the population increase, the high demand of energy from the residential sector, as well as the harsh weather conditions of the Las Vegas region, there needs to be careful consideration in the design of new homes. Energy efficiency in a single family residential building can be augmented early in the design process by careful consideration of the building form and orientation. A systematic investigation and analysis was taken to study the effects of five building forms and different orientations along the cardinal points using the software BEopt version 2.4.0.1. To connect the study to real world circumstances, a residential …

Fall Detection By Using Video, Robert J. Gripentog

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cameras have become common in our society and as a result there is more video available today than ever before. While the video can be used for entertainment or possibly as storage it can also be used as a sensor capturing crucial information, The information captured can be put to all types of uses, but one particular use is to identify a fall. The importance of identifying a fall can be seen especially in the older population that is affected by falls every year. The falls experienced by the elderly are devastating as they can cause apprehension to normal life …

Ediacaran Ocean Redox Evolution, Swapan Kumar Sahoo

UNLV Theses, Dissertations, Professional Papers, and Capstones

The relative role that environmental versus intrinsic biological factors played in

shaping the history of life on Earth is a fundamental but unanswered question in the

natural sciences. Most famously, it has been heavily debated if the emergence and

diversification of early animals during the Ediacaran Period (ca. 635–541 Ma) was tied to

a rise in atmospheric-oceanic oxygen levels. Temporally discontinuous geochemical data and patchy fossil record in literature are inadequate to chart the Ediacaran redox history and its causal relationship with the biotic evolution. My PhD study aims for a multiproxy geochemical record within a well-established stratigraphic framework of …

Simulation Of An Air Cooled Single-Effect Solar Absorption Cooling System With Evacuated Tube Collectors, Mohsen Jahandardoost

UNLV Theses, Dissertations, Professional Papers, and Capstones

Consistently increasing CO2 emission and ozone depletion from synthetic refrigerants are serious environmental issues challenging the scientific community. Absorption cooling systems give scope of utilizing low grade energy source for generating cooling effect. Solar energy is one of these low grade energy sources and with considering the fact that cooling demand increases with the intensity of solar radiation, solar refrigeration has been considered as a logical solution.

This thesis consists of two different simulation stages, in the first stage, a single effect lithium bromide absorption cooling system with constant cooling capacity is modeled and the effect of ambient and generator …

Generalized Catalan Numbers And Some Divisibility Properties, Jacob Bobrowski

UNLV Theses, Dissertations, Professional Papers, and Capstones

I investigate the divisibility properties of generalized Catalan numbers by ex-

tending known results for ordinary Catalan numbers to their general case. First, I define the general Catalan numbers and provide a new derivation of a known formula. Second, I show several combinatorial representations of generalized Catalan numbers and survey bijections across these representation. Third, I extend several divisibility results proved by Koshy. Finally, I prove conditions under which sufficiently large primes form blocks of divisibility and indivisibility of the generalized Catalan numbers, extending a known result by Alter and Kubota.

Rewetting Of Artificially Desiccated Soils: Effect Of Gravity On Vapor-Phase Diffusion, Taylor Arland Ball

UNLV Theses, Dissertations, Professional Papers, and Capstones

Soil desiccation has been suggested as an economically viable alternative for stabilizing water soluble contaminants in deep vadose zones such as at the Hanford Site. This approach would result in a large volume of the vadose zone being dried out in an effort to eliminate the transport mechanism for aqueous phase contaminants. Protecting the top and sides of the desiccated vadose zone from rewetting is a realistic possibility; however, it would be extremely difficult to restrict the upward migration of water from beneath the desiccated zone. One scenario related to the rewetting of the desiccated soil involves the upward migration …

Object Detection And Tracking In Wide Area Surveillance Using Thermal Imagery, Santosh Bhusal

UNLV Theses, Dissertations, Professional Papers, and Capstones

The main objective behind this thesis is to examine how existing vision-based detection and tracking algorithms perform in thermal imagery-based video surveillance. While color-based surveillance has been extensively studied, these techniques can not be used during low illumination, at night, or with lighting changes and shadows which limits their applicability. The main contributions in this thesis are (1) the creation of a new color-thermal dataset, (2) a detailed performance comparison of different color-based detection and tracking algorithms on thermal data and (3) the proposal of an adaptive neural network for false detection rejection.

Since there are not many publicly available …

Glass Shards At Pinnacle Point Rock Shelter 5-~6, South Africa: Are They From The Last Super-~Eruption Of Toba?, Amber Elizabeth Ciravolo

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cryptotephra, in the form of individual glass shards, have been discovered in paleoarchaeological site PP5-6 North at Pinnacle Point, Western Cape, South Africa. This marks the first documentation of cryptotephra in a South African paleoarchaeological site. PP5-6 North is a rock shelter in the cliffs along the coast of the Western Cape and is one of a series of caves and rock shelters at Pinnacle Point that were inhabited by early modern humans. The presence of cryptotephra at PP5-6 is an important discovery in terms of tephra preservation in cave deposits as well as the possibility of tephra being present …

Assessing The Importance Of Nurse Plant Associations To The Growth Of Pre-~Reproductive Yucca Brevifolia, Eric James Chameroy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Facilitation and competition among plant species, in addition to abiotic factors, play an important role in determining plant community structure in arid and semi-arid environments. I conducted a study in Dry Lake Valley, Lincoln County, Nevada, USA to investigate the importance of nurse plant associations to pre-reproductive Yucca brevifolia (Joshua tree). Dry Lake Valley lies within a transition desert between the Mojave and Great Basin Deserts with ecotonal plant communities consisting of species representative of both deserts. A vegetation survey described the communities in which this study was conducted as a Y. brevifolia woodland dominated by an understory of Ephedra …

Predictive Modeling Of Terrestrial Radiation Exposure From Geologic Materials, Daniel A. Haber

UNLV Theses, Dissertations, Professional Papers, and Capstones

Aerial gamma ray surveys are an important tool for national security, scientific, and industrial interests in determining locations of both anthropogenic and natural sources of radioactivity. There is a relationship between radioactivity and geology and in the past this relationship has been used to predict geology from an aerial survey. The purpose of this project

is to develop a method to predict the radiologic exposure rate of the geologic materials in an area by creating a model using geologic data, images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), geochemical data, and pre-existing low spatial resolution aerial surveys …

Solving Differential Equations With Least Square And Collocation Methods, Katayoun Bodouhi Kazemi

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this work, we first discuss solving differential equations by Least Square Methods (LSM). Polynomials are used as basis functions for first-order ODEs and then B-spline basis are introduced and applied for higher-order Boundary Value Problems (BVP) and PDEs. Finally, Kansa's collocation methods by using radial basis functions are presented to solve PDEs numerically. Various numerical examples are given to show the efficiency of the methods.

Designing, Building And Testing A Solar Thermoelectric Generation, Steg, For Energy Delivery To Remote Residential Areas In Developing Regions, Yacouba Moumouni

UNLV Theses, Dissertations, Professional Papers, and Capstones

New alternatives and inventive renewable energy techniques which encompass both generation and power management solutions are fundamental for meeting remote residential energy supply and demand today, especially if the grid is quasi-inexistent. Solar thermoelectric generators can be a cost-effective alternative to photovoltaics for a remote residential household power supply. A complete solar thermoelectric energy harvesting system is presented for energy delivery to remote residential areas in developing regions. To this end, the entire system was built, modeled, and then validated with LTspice simulator software via thermal-to-electrical analogy schemes. Valuable data in conjunction with two novel LTspice circuits were obtained, showing …

Characterization Of Gold And Related Mineralization At The North Bullion Carlin System, Railroad Project, A Nevada Carlin-~Type Gold Prospect, Melanie Nicole Newton

UNLV Theses, Dissertations, Professional Papers, and Capstones

A study of the North Bullion Carlin system, a Nevada Carlin-type gold prospect located on trend with the large Carlin-type gold deposits (CTGD) of the Carlin Trend, identified characteristics of ore and alteration mineralization, mineral paragenesis, and pyrite and whole rock geochemistry that are similar to characteristics that typify Carlin-type gold deposits. The North Bullion Carlin system is hosted in Devonian shelf carbonates and the Mississippian overlap assemblage, host rocks that are different from typical CTGD shelf-slope carbonate assemblage host rocks. The mineralogy and ore-stage gold-bearing pyrite rims at North Bullion are not as well developed as they are in …

Testing Established Models Of Hydrothermal Fluid Distribution Around Porphyry Deposits: The Application Of Fluid Inclusion Research To Porphyry Deposit Exploration, Wyatt Moyer Bain

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Kabba porphyry copper prospect in northwestern Arizona contains two zones of porphyry style mineralization and alteration, which are spatially separated by a north-south trending normal fault. These two zones are referred to as the Kabba footwall and hanging wall and are hypothesized to represent the root and intermediate depth levels of the same porphyry-like hydrothermal system, respectively. If this hypothesis is correct, then fluid inclusions found in the hanging wall and footwall should have the physical and chemical characteristics of fluid inclusions in the root and intermediate depth levels of other known porphyry deposits. Vein and alteration petrography, fluid …

Alkali-~Activated Fly Ash Binders: Feasibility As A Sustainable Alternative To Ordinary Portland Cement For Pre-~Cast Systems, Kimberly Sierra

UNLV Theses, Dissertations, Professional Papers, and Capstones

Fresh, load-dependent, transport, and durability properties of alkali-activated fly ash mortars were studied. The influences of activator concentration, solution-to-binder ratio, curing condition, activator type, and sodium silicate-to-total solution ratio on the properties of the studied alkali-activated mortars were examined. This study was divided in two phases. The first phase dealt with the use of sodium hydroxide as the sole activator. The second phase of the study was divided into two parts, both of which used a combination of sodium hydroxide and sodium silicate as the activator solution. Part I of phase II used elevated temperature curing conditions, whereas part II …

An Investigation Into Transitions In Clay Mineral Chemistry On Mars, Seth Gainey

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation is comprised of three studies investigating clay mineralogy on, or near the martian surface, with an introductory chapter, introducing and linking the three studies. Chapter two is on the subject of clay mineral synthesis, including Fe/Mg clay minerals which have been detected at multiple locations across the southern highlands. These Fe/Mg clay minerals have been previously interpreted as forming in anoxic/reducing environments, conducive to the preservation of organic matter. The results of this study suggest that the previous interpretation of Fe/Mg-rich clay as requiring anoxic/reducing conditions may not be accurate, as the minor presence of Mg (below what …

Structure And Optical Properties Of Transition Metal Dichalcogenides (Tmds) – Mx2 (M = Mo, W & X = S, Se) Under High Pressure And High Temperature Conditions, Nirup Reddy Bandaru

UNLV Theses, Dissertations, Professional Papers, and Capstones

Layered structured materials such as transition metal dichalcogenides (TMDs) have gained immense interest in recent times due to their exceptional structural, electrical and optical properties. Recent studies show semiconducting TMDs such as MX₂ (M= Mo, W & X = S, Se) could be used as potential shock absorbing material, which has resulted in extensive studies on structural stability of these materials under the influence of high pressure. Understanding the structural stability of transition metal dichalcogenides (TMDs) such as MoS2, MoSe2, WS2, and WSe2 under high pressure has been very challenging due to contradicting observations and interpretations reported in the …

Stable Isotope Analysis Of Bison Latifrons And Paleoecological Inferences, Fabian Ceron Hardy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Bison latifrons was a large Pleistocene herbivore that is traditionally hypothesized to have been adapted to living in forest openings and woodlands. According to this view, the species was primarily a browser of high-growing, woody plants. Very little isotopic work has been conducted on this species, and there have been no prior studies of high altitude localities containing this species. This study aims to address both of these issues.

B. latifrons is known from sites in several states, including California, Idaho, Colorado, Nevada, and Florida, among others. These sites provide diverse examples of this species’ habitat and the opportunity to …

Laser Ablation Icp-Ms Of Actinide Oxides As Simulated Used Nuclear Fuels, Keri Campbell

UNLV Theses, Dissertations, Professional Papers, and Capstones

The ability to examine elemental and isotopic ratios of fuels, waste forms, and other solids by direct analysis using laser ablation techniques can greatly reduce analysis costs and time. This is particularly true for actinide elements, as they contain useful information of the fuel cycle and nuclear forensics. Current methods to evaluate the composition of used fuel include a lengthy process of digestion, separations and often require multiple techniques and sample preparations to determine the elemental and isotopic composition. Furthermore all spatial information is lost during the digestion process, eliminating potentially useful data for detailed analysis. The goal of this …

Development Of A Decision Support Framework For The Planning Of Sustainable Transportation Systems, Pankaj Maheshwari

UNLV Theses, Dissertations, Professional Papers, and Capstones

With the rapid increase in economic development throughout the world, there is stress on the resources used to support global economy, including petroleum, coal, silver, and water. Currently, the world is consuming energy at an unprecedented rate never seen before. The finite nature of such non-renewable natural resources as petroleum and coal puts pressure on the environmental system, and ultimately reduces the availability of resources for future generations. Hence, it is critical to develop planning and operational strategies that seek to achieve a sustainable use of existing natural resources.

With this motivation, this dissertation focuses to develop a decision support …

A Survey Of Network Coding And Applications, Jonny L. Winger

UNLV Theses, Dissertations, Professional Papers, and Capstones

Common networks with source, internal, and destination nodes put data packets in queues for forwarding.Network coding aims to improve network throughput and energy consumption by combining received data packets before forwarding. In this survey, we will explore various network coding schemes, along with the behavior of network coding in applications. Sensor, wireless routing, and distributed storage networks can benefit greatly from network coding implementations. Flooding is a procedure in distributed systems which broadcasts a message to all nodes in the network. NC-Flooding is introduced, which uses network coding to possibly decrease the message complexity and/or time complexity of flooding.

Constructing Bfs Trees Using Tokens To Balance Speed And Network Traffic, Michael Spencer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Constructing BFS trees rooted at each node of a network helps solve many problems. Reliable communication to other nodes is easily managed and metrics such as the network diameter, shortest path between any two nodes, the center, the radius, and others can be easily computed. A traditional way to form a BFS tree from each node is for all nodes to construct their trees in parallel. While this is the fastest way to accomplish this task, it also requires a large amount of network traffic. In this thesis, we present a way to use a token passing algorithm to form …

The Presence Of Clostridium Difficile On Environmental Surfaces In Healthcare Facilities Pre- And Post-Decontamination Of Patient Rooms, Theresa Trice

UNLV Theses, Dissertations, Professional Papers, and Capstones

Healthcare-associated infections (HAIs) are infections related to receiving medical care. HAIs are responsible for an excess of morbidity and mortality among hospitalized patients. Though most HAIs rates are on the decline, Clostridium difficile infection rates are at an all-time high, primarily due to the persistence of C. difficile spores in the environment. In the United States, Clostridium difficile-related mortality rates per million have increased from 5.7 in 1999 to 23.7 in 2004, with an estimated 26,642 deaths due to Clostridium difficile infections (CDIs). Clostridium difficile is transmitted via the fecal-oral route or aerosolized endospores, but it can also be transmitted …

Inverse Problem For Non-Viscous Mean Field Control: Example From Traffic, Shaurya Agarwal

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis presents an inverse problem for mean field games where we find the

mean field problem statement for which the given dynamics is the solution. We use

distributed traffic as an example and derive the classic Lighthill Whitham Richards

(LWR) model as a solution of the non-viscous mean field game. We also derive

the same model by choosing a different problem where we use travel time, which

is a distributed parameter, as the cost for the optimal control. We then study the

stationary versions of these two problems and provide numerical solutions for the

same.