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Optimization Of Channel Geometry In A Proton Exchange Membrane (Pem) Fuel Cell, Jephanya Kasukurthi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Bipolar plates are the important components of the PEM fuel cell. The flow distribution inside the bipolar plate should be uniform. Non-uniform flow distribution inside the bipolar leads to poor performance of the fuel cell and wastage of expensive catalyst. A single channel PEM fuel cell is taken and electrochemical analysis is carried out on it. The results are compared with the available published experimental data obtained by other research group, and they are found to be in good agreement. A baseline design of the bipolar plate is taken and numerical analysis is carried out. The results show that the …

Spectral Analysis Of Pathological Acoustic Speech Waveforms, Priyanka Medida

UNLV Theses, Dissertations, Professional Papers, and Capstones

Biomedical engineering is the application of engineering principles and techniques to the medical field. The design and problem solving skills of engineering are combined with medical and biological science, which improves medical disorder diagnosis and treatment. The purpose of this study is to develop an automated procedure for detecting excessive jitter in speech signals, which is useful for differentiating normal from pathologic speech. The fundamental motivation for this research is that tools are needed by speech pathologists and laryngologists for use in the early detection and treatment of laryngeal disorders. Acoustical analysis of speech was performed to analyze various features …

Evaluation Of Extraction Chromatography Resins For Rapid Actinide Analysis, Julie Marisa Gostic

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this work, physical and chemical parameters associated with extraction chromatography separation procedures were investigated for rapid actinide analysis. A vacuum box system was designed in-house and was characterized in terms of flow rate reproducibility, matrix effects on flow rate for sequential elution, and actinide separation efficiency using different types of resin (TEVA, DGA and TRU). Results indicated that the columnar kinetics of the resins were sufficiently rapid to run high purity samples through the unit over a wide range of flow rates for all resin types. Single matrix interferences at a metal ion ratio of 1:10 6 relative to …

Estimating The Indirect Contribution Of Sports Books: Sports Wagering As A Driver Of Other In-House Revenues, Brett L.L. Abarbanel

UNLV Theses, Dissertations, Professional Papers, and Capstones

Using data from a repeater market hotel in Las Vegas, Nevada, the relationship between sports book and slot machine revenues is examined. Daily sports book write and daily slot handle are compared over a 250 day period. Though many industry leaders theorize that sports book gamblers also wager in slot banks, the results of this research fail to demonstrate a statistically significant relationship between sports book write and slot coin-in. In addition, the model used included race book win as an independent variable. Race book win was found to be a highly insignificant indirect contributor to slot revenue volume and …

Hierarchical Routing In Manets Using Simple Clustering, Adam Carnine

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis presents both a review of current MANET routing protocols and a new MANET routing algorithm. The routing protocols reviewed include representative samples from the three primary forms of routing found in MANETS: proactive routing, reactive routing and hybrid routing. Secure algorithms are given special treatment in the review. In addition several protocol enhancements are discussed.

The proposed routing protocol is designed to support networks of a medium size, containing over 200 nodes but less than 3,000 nodes. The design is intentionally simple to allow ease of implementation in comparison with other MANET protocols that provide similar functionality.

Criticality Studies Of Actinides Within Fissures, Trevor Wilcox

UNLV Theses, Dissertations, Professional Papers, and Capstones

The storage of nuclear waste in underground storage facilities presents numerous engineering challenges and risks. Experimental verification of engineered underground storage is impractical or prohibitively expensive, leaving scientists with few options. A 1995 report by Bowman and Venneri of the Los Alamos National Laboratory generated considerable controversy by hypothesizing that wastes composed of fissionable plutonium leached from underground storage containers could pose a nuclear criticality hazard. They proposed cases where plutonium collected in underground fractures could lead to sustained nuclear fission. In overmoderated cases, they argued that the resulting release of energy from fission could result in steam explosions, or …

Geoelectrical Response Of Surfactant Solutions In A Quartzitic Sand Analog Aquifer, Meghan Therese Magill

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this project, the resistivity and phase shift of ten surfactant aqueous solutions in a sand matrix were measured using spectral induced polarization (SIP). In addition, specific conductivity, pH, dissolved oxygen, and dielectric constant measurements of the solutions were also evaluated. The frequency range assessed was 0.091-12000Hz. The surfactants, which are typically used in the remediation of tetrachloroethylene, were Aerosol MA 80-I, Dowfax 8390, and Steol CS-330. The surfactants were mixed into solutions of both deionized and tap water at varying concentrations and injected into a closed system of silica sand. The surfactant treatments altered resistivity, specific conductivity, and pH …

Experimental And Numerical Study Of A Proton Exchange Membrane Electrolyzer For Hydrogen Production, Sachin S. Deshmukh

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen as a fuel source has received attention from researchers globally due to its potential to replace fossil based fuels for energy production. Research is being performed on hydrogen production, storage and utilization methods to make its use economically feasible relative to current energy sources. The PEM electrolyzer is used to produce hydrogen and oxygen using water and electricity. Focus of our study is to provide a benchmark experiment and numerical model of a single cell electrolyzer that can assist in improving the current state of understanding of this system. Parametric analysis of an experimental cell was performed to understand …

Tensile Strength And Failure Criterion Of Analog Lithophysal Rock, James A. Nott

UNLV Theses, Dissertations, Professional Papers, and Capstones

This project determines the tensile strength of lithophysal analog rock and presents failure criteria that can be used by geotechnical engineers to evaluate underground structures in rock. The physical and mechanical properties that are related to the failure criterion, such as porosity, compressive strength and modulus of elasticity, are also discussed. Experimental tensile tests were made using direct uniaxial and indirect Brazilian tests. Three 4-inch specimens were fabricated and tested in direct uniaxial tensile tests using Hydro-Stone TB. The results showed that the elastic tensile modulus of elasticity was within two percent of existing data for the compressive modulus of …

High Pressure Phase Transistions In The Lanthanide Sesquioxides, Jason Patrick Mcclure

UNLV Theses, Dissertations, Professional Papers, and Capstones

Crystallizing into 5 known polymorphic forms, the rare-Earth sesquioxides RE 2 O 3 represent a family of 4-f electron compounds that have been the subject of study for many years. Aspects of the systematics in the structural phase transitions for RE 2 O 3 (RE=La, Sm, Eu, Gd, Y, Er, Yb, Lu) under pressure were studied using diamond anvil cells (DACs). As a part of this study, detailed equation of state (EOS) data for all these compounds were obtained through the use of angle-dispersive x-ray diffraction (XRD) where anomalies in compression data led to the detailed investigation into one particular …

Teacher Candidates' Attitudes Toward Immigration And Teaching Learners Of English As A Second Language, Midena M. Sas

UNLV Theses, Dissertations, Professional Papers, and Capstones

While in theory, democratic ideals promise the equal participation of all its citizens in the decisions that affect them, in practice some populations, i.e., those who do not possess membership to the dominant cultural group, often miss out on the privileges a democratic society is supposed to ensure. Critical theorists pointed out that "democracies like ours exhort equal opportunity but often ignore ways in which our schools operate unconsciously and unknowingly to guarantee that there will be no real equality" (McLaren, 2007, p. 176). In the education arena, inequitable treatment has received significant attention, perhaps due to the glaring repercussions …

Soil Moisture And Water Stage Estimation Using Precipitation Radar, Sumit Puri

UNLV Theses, Dissertations, Professional Papers, and Capstones

In south-western United States, soil moisture data is important for drought studies in the region which is experiencing a drought for many years, whereas in South Florida, water stage data is required by hydrologists to monitor the hydrological flow in wetlands. Soil moisture data and water stage data are not sufficiently available due to sparse monitoring stations. Installation of dense measuring stations over an extended area is costly and labor intensive. Therefore, there is a need to develop an alternative method of measuring soil moisture and water stage. Microwave remote sensing has proven to be a useful tool in the …

Provenance Of The Miocene-Pliocene Muddy Creek Formation Near Mesquite, Nevada, Steven Wayne Forrester

UNLV Theses, Dissertations, Professional Papers, and Capstones

The provenance, stratigraphy, and depositional history of the Miocene-Pliocene Muddy Creek Formation (MCF) in southern Nevada are poorly studied and poorly constrained. Previous studies of the MCF have concluded that the formation consists of lacustrine, eolian, and fluvial deposits. Currently the age of deposition is loosely constrained between 8.5 and 4.1 Ma. This study documents the evolution of one portion of the eastern extent of the MCF and determines its provenance and depositional history at Flat Top and Mormon Mesas in Nevada; and near Beaver Dam and Littlefield, Arizona.

This study intended to determine whether the MCF was deposited by …

Spectroscopic Investigation Of Palladium-Copper Bimetallic Systems For Pem Fuel Cell Catalysts, Timo Hofmann

UNLV Theses, Dissertations, Professional Papers, and Capstones

One of the main barriers to commercialization of polymer electrolyte membrane fuel cells systems is cost, which is largely due to the need of platinum (Pt)-containing catalysts. In this thesis we investigate bimetallic systems consisting of a base metal (copper) and a noble metal (palladium) that, as an alloy on the nanoscale, mimic the electronic properties that make Pt desirable as a catalyst.

We present a detailed investigation of the electronic structure of carbon-supported Pd/Cu nanoparticle catalysts, model bilayer thin film systems, alloys, and various metal reference samples. We have investigated the valence band structure of the catalysts using a …

Mitigation Of Impact Vibrations Using Impedance Mismatch In Cylindrical Structures, Sachiko Sueki

UNLV Theses, Dissertations, Professional Papers, and Capstones

The focus of this work is to study the phenomenon of material impedance mismatch to determine its effect on the mitigation of high frequency accelerations in projectile and long bar structures within linear ranges of materials. In this study, the acceleration responses of structures with various materials and material combinations were studied experimentally, numerically and by the Finite Element Analysis (FEA). Air-gun tests conducted by the US Army Research Laboratory were modeled using FEA to simulate the acceleration pulse and shock waves experienced by artillery components during a launch. After the prototype of projectile was selected, further studies were conducted …

An Evaluation Of Lead Hazards In Pre-1978 Residental Housing Within Clark County, Nevada, Usa, Erika Raquel Torres

UNLV Theses, Dissertations, Professional Papers, and Capstones

Lead poisoning remains a public health concern due to leads persistence in the environment from anthropogenic uses. Initial efforts to address the impacts of lead on vulnerable communities have included secondary prevention measures which typically occur after a child has been poisoned. However, in recent years there has been a pragmatic shift toward primary prevention efforts.

This study evaluates lead hazards identified through primary prevention activities in residential housing within Clark County, Nevada, USA. It is the first study to systematically address and evaluate pre-1978 housing in Southern Nevada. Risk assessments were conducted in 81 dwellings built prior to 1979 …

Examining The Influence Of Restaurant Green Practices On Customer Return Intention, Audrey L. Szuchnicki

UNLV Theses, Dissertations, Professional Papers, and Capstones

In recent years there has been an increased awareness of how the actions of the foodservice industry are effecting the environment. With this awareness we have begun to see a change in priorities for both new and existing businesses. At the forefront of this change in the "green" direction is the GRA who certifies how eco-friendly an establishment is based on its' environmental guidelines. This study will examine the correlation between customer return intention and the institution of green practices within a restaurant setting. The expected outcome would be that a restaurant that is certified green or, implementing measures to …

Passage And Initial Implementation Of The Supplemental Educational Services Element Of The No Child Left Behind Act: An Historical Inquiry Study, Brad D. Christensen

UNLV Theses, Dissertations, Professional Papers, and Capstones

With reports alleging a sharp decline in student achievement in the last several years, there has been a call for higher standards in the United States education system. In response, with bipartisan support, politicians overwhelmingly passed the No Child Left Behind (NCLB) Act of 2001. NCLB, the most recent reauthorization of the Elementary and Secondary Education Act (ESEA), mandated increasing the educational performance of all children by focusing on accountability for student achievement, flexibility, higher academic standards, research-based reforms, parental choice, annual testing to measure student progress, analysis of the annual testing data, and sanctions for schools where students did …

Islanded Operation Of A Distribution Feeder With Distributed Generation, Chandu Venu

UNLV Theses, Dissertations, Professional Papers, and Capstones

A distribution system that is equipped with distributed generators, such as roof-mounted photovoltaic systems, can operate as a microgrid (i.e., separated from the grid) under some specific conditions. A key feature of a microgrid is its ability to separate and isolate itself from the utility seamlessly with little or no disruption to the loads within the microgrid. Then, when the utility grid returns to normal, the microgrid automatically resynchronizes and reconnects itself to the grid, in an equally seamless manner. This thesis addresses the conditions necessary for proper microgrid operation: these include local generation-load mismatch, local energy storage, load switching, …

Effects Of Explicit Subtraction Instruction On Fifth Grade Students With Learning Disabilities, Danielle Ferreira

UNLV Theses, Dissertations, Professional Papers, and Capstones

This study involved an investigation of the effects of strategy instruction integrated with the concrete-representational-abstract teaching sequence on students with learning disabilities. A multiple probe design across subjects with one replication was used in this study. Two sets of data were analyzed to determine effectiveness of the independent variable (intervention lessons). The first data set consisted of pre and posttest percentage scores and the second data set consisted of baseline, intervention, and maintenance probe scores that were collected throughout the study per the parameters of a multiple probe design. The probe scores were plotted in line graph format and analyzed …

On-Board Three-Dimensional Object Tracking: Software And Hardware Solutions, Ajay Kumar Mandava

UNLV Theses, Dissertations, Professional Papers, and Capstones

We describe a real time system for recognition and tracking 3D objects such as UAVs, airplanes, fighters with the optical sensor. Given a 2D image, the system has to perform background subtraction, recognize relative rotation, scale and translation of the object to sustain a prescribed topology of the fleet. In the thesis a comparative study of different algorithms and performance evaluation is carried out based on time and accuracy constraints. For background subtraction task we evaluate frame differencing, approximate median filter, mixture of Gaussians and propose classification based on neural network methods. For object detection we analyze the performance of …

Extents And Limits Of Radioscopic Detection Of Nuclear Materials In Cargo Containers With Two Megavoltage Energy Barriers, Vijay Kumar Mandava

UNLV Theses, Dissertations, Professional Papers, and Capstones

The megavoltage X-ray technology is utilized for detecting nuclear materials in cargo containers. Interlaced response is obtained by switching rapidly between 6MeV and 9 MeV beams. It is known that the ratio of penetration levels of cargo contents taken at nominal and dual energies provides the information about atomic numbers of materials, and thus can also indicate the threat group. However, the identification is not straightforward if combinations of materials are present. The latter can lead to misdetections. It is imperative to know what are the extent and the limit of the currently employed technology, and how to carry out …

Empirically Derived Formulas To Predict Indoor Maximum, Average, And Minimum Temperatures In Roofpond Buildings Using Minimum Climatic Information, Ibrahim Kivarkis Kako

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis introduces an empirically developed formula to predict the comfort conditions and thermal performance of a Skytherm(TM) Southwest Roofpond placed over a light-weight un-insulated structure built at the School of Architecture at the University of Nevada, Las Vegas.

The predictive formula introduced in this study may be used in different parts of the world (particularly developing nations where insulation and air-conditioning are rarely used) to predict the performance of a Skytherm(TM) Southwest Roofpond using minimal climate data.

The data collected in the experimental setup at the Natural Energies Advanced Technologies Laboratory included outside and inside temperatures of various surfaces …

Quantity-Based Cost Forecasting System For Street Construction Projects, Nipesh Pradhananga

UNLV Theses, Dissertations, Professional Papers, and Capstones

Construction projects typically are not withdrawn after going into the competitive bidding process. The decision of contracting authorities regarding which projects will proceed to the bidding stage depends, in part, upon the early estimates of probable cost. Efforts are made to make this estimate as realistic as possible. Irrespective of the estimate of probable cost, the actual project cost is established by the amount of the winning bid.

This study analyzed historical bid data of street construction projects undertaken by the Public Works Department, Clark County, Nevada, from 1991 through 2006. The focus of this study was on utilizing statistical …

Optimal Design Of Discrete-Time Delta Sigma Modulators, Matthew Edward Jackson

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this thesis, optimal signal transfer functions (STFs) and noise transfer functions (NTFs) for discrete time delta sigma (ΔΣ) modulators are determined. For a given oversampling rate (OSR), these STFs and NTFs are optimized with respect to a weighted combination of the ΔΣ modulator's signal-to-noise ratio (SNR) and dynamic range (DR). This optimization problem is solved using a novel hybrid orthogonal genetic (HOG) algorithm that uses customized genetic operators to improve algorithm performance and accuracy when applied to multimodal, non-differentiable performance surfaces. To generate optimal system functions, the HOG algorithm is implemented as a constrained global optimizer to minimize cost …

Nevada Interagency Volunteer Program: Helping Hands Across Public Lands – Phase Ii: Quarterly Progress Report, Period Covering October 1 – December 31, 2008, Margaret N. Rees

Get Outdoors Nevada

• The number of records in the volunteer database increased 8% over last quarter. The database now contains 6,431 records.
• Website activity increased, recording an average of 56,013 hits per month, an increase of 6% from last quarter, with an average of 5,211 pages viewed per month.
• Volunteer fall training has been completed.
• Three National Public Land Day and National Family Events have been completed.
• Two hundred and five people attended the Volunteer Recognition Event.

Limnological Assistance For The Lake Mead National Recreation Area In Meeting The Challenge Of The Water 2025 Initiative: Quarterly Report, Period Ending December 31, 2008, Margaret N. Rees

Limnological Studies

Project 1: Technical input has been provided at four advisory team meetings attended this quarter.

Project 2: A formal report titled, Surface Water Monitoring for Indicator Bacteria in High-use Sites of the Lake Mead National Recreation Area, has been prepared; an accompanying poster presentation for the Lake Mead Science Symposium is in preparation.

Project 3: A draft document titled, “Interagency Monitoring Action Plan (I-MAP): Quagga Mussels in Lakes Mead and Mohave” has been presented to an interagency core group to review and input. Six oral presentations related to quagga mussels are in preparation by this group for the Lake Mead …

Lake Mead National Recreation Area Monitoring And Evaluation Of Sensitive Wildlife: Quarterly Progress Report, Period Ending December 31, 2008, Margaret N. Rees

Wildlife Monitoring

Project 1. Relict Leopard Frog Monitoring, Management, and Research

• All milestones and deliverables associated with the MSHCP project are on schedule
• Completion of 2008 monitoring survey efforts
• Coordination is ongoing to identify potential translocation sites, including assisting efforts to identify a potential site in the western Grand Canyon
• RLFCT meeting hosted and minutes of meeting drafted
• Annual report provided to RLFCT, final draft in review
• Sampling for the amphibian chytrid fungus conducted at many sites

Project 2. Bald Eagle Winter Monitoring and Evaluation

• All MSHCP milestones and deliverables are on schedule
• Planning and coordination of the 2009 Eagle Count conducted …

Final Report: Task 22 — Extreme Ground Motion Studies, John G. Anderson, James N. Brune, Jaak J.K. Daemen, Matthew Purvance

Publications (YM)

TASK 22 consisted of two separate investigations into extreme ground motions due to seismic events, Subtask 1 and Subtask 2. Subtask 1 included field studies of geological formations that should put an upper bound on extreme ground motions that have happened at the site of the formations. The locations are critically selected to provide the most effective constraints possible on the validity of the probabilistic seismic hazard analysis for Yucca Mountain. Subtask 2 surveyed recorded ground motions from around the world, with the aim to draw general conclusions from these as to the conditions where extreme ground motions are observed. …

Early Post-Fire Recovery On A Heavily Visited Mojave Desert Burn: Red Rock Canyon Near Las Vegas, Nevada, Scott R. Abella, E. Cayenne Engel, Christina L. Lund, Jessica E. Spencer

Fire Science Presentations

Wildfire has become widespread in southwestern USA deserts. In a record 2005 fire season in the Mojave Desert, for example, more than 385,000 hectares burned (Brooks and Matchett 2006). This burned area is approximately 3% of the entire Mojave Desert. Fueled in large part by exotic annual grasses, these fires burned desert ecosystems thought to have only burned infrequently historically. Burns now occupy significant portions of desert landscapes, posing prominent management challenges. Improving our understanding of plant recovery on desert burns is important for evaluating future fire hazard, whether natural revegetation will meet management objectives, and for planning active revegetation …