Digital Commons Network^™

Performance Effects Of Dissociated Hydrogen In Nuclear Thermal Propulsion Engines, Richard Adam Gorrell

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nuclear thermal propulsion (NTP) research considers hydrogen dissociation as negligible to design and analysis of propulsion engines. This study reintroduces chemically reacting flow to NTP engine analysis for investigation of the dissociation effect on engine performance. A first-principles approach observes the basic chemical mechanism and reaction within the high-speed, high-temperature NTP flow to baseline expected atomic hydrogen levels and validate equilibrium. A surface reaction study looks into hydrogen absorption through dissociation and its effect on the boundary layer, and bulk flow. For total performance, the resulting dissociated flow is analyzed through nozzle expansion and performance metrics calculated.

All historic reactor …

Regulation Of Embryonic Eye Regrowth In Xenopus Laevis, Dylan Guerin

UNLV Theses, Dissertations, Professional Papers, and Capstones

Regrowth of lost organs and tissues is an amazing ability that some animals possess. For regrowth to be considered full, the organism must regrow the organ or tissue to a state that is structurally and functionally similar to that which was lost. The ability of an organism to regrow lost or damaged tissue varies among animals, both in the mechanisms utilized to achieve regrowth, and in what body parts can be regrown. Potentially even closely related species can vary wildly in regenerative ability. Therefore, regenerative research can look to other tissues and organisms for direction in elucidating the mechanisms through …

Redirection Of Current In A Dense Plasma Focus, Rocky Gonzalez

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Mission Support & Test Services (MSTS) reports that significant amounts of energy needed for generating high energy neutrons is lost within a Dense Plasma Focus between its pinch-end of the anode stalk and at its base near the insulating sleeve. It is their mission and the goal of this research effort to both experimentally and theoretically study current redirection in a DPF during and after pinch dynamics. It is hypothesized that current redirection, due to restrike, behind the dynamic sheath of a dense plasma focus will result in a measurable change in the magnetic field along the longitudinal axis …

Promoting Situational Interest In Computer Science Classroom: A Utility Intervention Approach, Mustafa Gunozu

UNLV Theses, Dissertations, Professional Papers, and Capstones

Mastery of computer science and computational reasoning emerges as an essential skill for every student. Experts recommend increasing the focus on computer science studies due to their crucial role in the future, recognizing its pivotal role in early learning. The present study aimed to evaluate the impact of a utility-based intervention on enhancing middle school students' interest in computer science. This study adopted a utility value intervention method to improve students' situational interest in computer science within a formal setting. The study investigated how a utility intervention changes students' interests in the content, employing a pretest-posttest control group design. For …

Roadblocks To Momentum: An Analysis Of College Major Gpa Restrictions And Stranded Students, Michael J. Hack

UNLV Theses, Dissertations, Professional Papers, and Capstones

College retention, persistence, and completion are key indicators of a successful institution, but six-year degree completion has remained stagnant in recent years (National Student Clearinghouse Research Center, 2022). Despite institutional efforts through success initiatives to keep students retained, one set of barriers to degree completion may be due to established major GPA restrictions and policies that prevent students from being able to declare their majors. Accordingly, students who are unable to declare their major but keep enrolling in courses may be in danger of becoming “stranded.” This quantitative examination of student data from one large public four-year college aims to …

Removal Of Permethrin And Bifenthrin Insecticides From Runoff Water By Activated Carbon Adsorption, Ernesto Hernandez

UNLV Theses, Dissertations, Professional Papers, and Capstones

Among the hundreds of pesticides and insecticides, pyrethroids-particularly permethrin and bifenthrin, have become very popular due to their high toxicity to insects and low toxicity to humans, leading to extensive use in both agriculture and urban areas. Pyrethroids have no discharge limits because of this, leading to a negative impact on surrounding ecosystems due to their high toxicity to fish and aquatic life. Due to their low solubility and long half-lives, they are prominent in the environment long after application with a high potential for getting transported in runoff water to nearby water bodies. In this study, DSR-C reactivated carbon …

Surface Coating Method For Cement-Based Materials To Improve Chloride Ion Penetration Resistance Using Amine-Based Co2 Solvent, Seongho Han, Tae Hoon Han, Jae Hong Kim

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The application of coatings on concrete surfaces serves as a protective shield, guarding the structure against chlorides and averting corrosion of the reinforcement, consequently enhancing its durability. This study investigates the resistance of cement mortar samples to chloride ion penetration when coated with an amine-based carbon dioxide (CO2) solvent. Various factors, including monoethanolamine (MEA) concentrations of 1, 10, and 30 wt.%; water-to-cement ratios (w/cm) of 0.35, 0.4, and 0.5; coating timings on day 3 and day 27; and pre-conditioning methods such as air drying, are investigated for their impact on the performance of chloride penetration resistance. Specifically, pre-conditioning significantly enhanced …

Modeling Inflation Transmission Among Different Construction Materials, Mohamad Abdul Nabi, Islam H. El-Adaway, Rayan H. Assaad

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Cost estimating in the construction industry is challenging due to the high uncertainty associated with the supply chain, especially after the COVID-19 pandemic. Some research studies have addressed such problems by developing models that predict material cost. In fact, all material can be interconnected and interrelated with lead-lag relationships such that any inflation in one material's price can be associated with inflation in other materials' prices, referred to as transmission of inflation. Despite the latter, none of the existing studies have investigated inflation transmission among all construction materials. This paper fills this knowledge gap. The authors used a multistep research …

A Review Of Whipple Shield Ballistic Limit Equations, S. Ryan, W. (William) P. Schonberg

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Ballistic limit equations (BLEs) are semi-analytical expressions used to predict the risk posed by micrometeoroid and orbital debris (MMOD) impacts on a spacecraft. A foundational BLE, known as the new non-optimum (NNO) equation was published by Eric Christiansen of NASA Johnson Space Center in 1990 for application on Whipple shields – two-plate configurations consisting of a thin sacrificial plate located at some standoff in front of the spacecraft pressure hull or structural wall. Today, BLEs for almost all multi-plate spacecraft structures, e.g., honeycomb sandwich panels, monolithic structures with thermal insulation blankets, etc., are based on the NNO Whipple BLE. We …

Investigating Causes Of Disputes Resulting In Litigation In Airport Development Projects In The United States Using Graph-Based Techniques, Ramy Khalef, Islam H. El-Adaway

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Airports represent a crucial a sector of the US infrastructure, but they were documented to have scored a D+. To mitigate this, governmental authorities have issued initiatives to update the airport infrastructure. With an expected critical junction for a major transformation in the airport sector, it is anticipated that airport projects will increase. This shall result in an escalation in the number of disputes. Previous research analyzed dispute concerns within the construction sector, but none tackled the perspective of airport projects. Accordingly, the goal of this study is to investigate the leading causes of disputes in litigation within US airport …

Analysis Of Single Event Transients In Arbitrary Waveforms Using Statistical Window Analysis, James Carpenter

Masters Theses and Doctoral Dissertations

Window functions are commonly used in data processing to detect transient events or for time-averaging of frequency spectra. A generalized window function is demonstrated using the Ionizing Radiation Effects Spectroscopy (IRES) technique to enhance the measurement of transient anomalies within arbitrary waveforms. The IRES filter convolves time data with a sliding window consisting of a moment-generating function. The resulting time-dependent statistical moments are used to eliminate any steady-state signatures, including noise, and extract transient behaviors. The IRES filter analyzes data from heavy-ion exposures of commercial off-the-shelf (COTS) operational amplifiers, laser-induced transients in Complementary Metal-Oxide-Semiconductor (CMOS) phase-locked loops, and simulated transients …

Investigations Into The Role Of Entropy-Selected Rf-Dna Fingerprint Features On Id-Verification Performance In The Presence Of Rogue Emitters, Awab Mohammed

Masters Theses and Doctoral Dissertations

The Internet of Things (IoT) is projected to reach 30.9 billion devices by 2025. However, most lack adequate security measures against sophisticated threats. Specific Emitter Identification (SEI) is a crucial security approach for authenticating wireless emitters. This work integrates RF-DNA fingerprinting, a specialized form of SEI, with Deep Learning (DL) techniques to authenticate the identity of authorized emitters. This authentication becomes crucial in the presence of “rogue” emitters who deliberately impersonate authorized emitters using falsified digital credentials. The RF-DNA fingerprints are extracted from the entropy-selected regions within the TF representations of an emitter’s signals. The obtained results demonstrate the success …

The Influence Of Personal Factors On Wrongful Convictions, Ellee Jackson

Masters Theses and Doctoral Dissertations

Previous work has identified factors that influence the likelihood of wrongful conviction. However, fewer efforts have been made to examine how these factors influence the amount of time between wrongful conviction and exoneration. This is crucial to the expansion of innocence research and the contextualization of wrongful convictions within the criminal justice system. This study employs negative binomial regression to analyze data collected by the National Registry of Exonerations (NRE). Using a sample of 2,349 cases in which the most severe conviction was murder, sexual assault, child sexual abuse, or drug possession, I examine the influence of an exoneree’s age, …

Fate And Treatability Of Engineered Nanoparticles In Urban Stormwater, Laura Wright

Masters Theses and Doctoral Dissertations

Despite the tremendous benefits of engineered nanoparticles (ENPs), their inevitable release into the environment may be detrimental and hence cause for concern of these emerging contaminants. In this thesis research, the fate and transport of nano-silver (n-Ag) and nano-titanium dioxide in source specific stormwater is explored, and the influence of n-Ag on the treatability of co-pollutants is examined. Through the analysis of particle size distribution, it was noticed that metallic ENPs tend to aggregate initially, while extended turbulence in the system leads to disaggregation. Stormwater samples with added ENPs exhibited larger particles than those in stormwater without added ENPs. The …

The Non-Vanishing Of The Trace Of T ₃, Liubomir Chiriac, Daphne Kurzenhauser, Erin Williams

Mathematics and Statistics Faculty Publications and Presentations

A generalized Lehmer conjecture predicts that, for every positive integer n, the trace of the Hecke operator T_n in level one does not vanish, unless the space of cusp forms acted upon is trivial. So far, this has only been established for n = 2. In this paper, we use p-adic methods to prove the statement for n = 3.

Effect Of Pre-Heating On Residual Stresses And Deformation In Laser-Based Directed Energy Deposition Repair: A Comparative Analysis, Usman Tariq, Sung Heng Wu, Muhammad Arif Mahmood, Michael M. Woodworth, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser-Directed Energy Deposition (DED), a Metal Additive Manufacturing Method, is Renowned for its Role in Repairing Parts, Particularly When Replacement Costs Are Prohibitive. Ensuring that Repaired Parts Avoid Residual Stresses and Deformation is Crucial for Maintaining Functional Integrity. This Study Conducts Experimental and Numerical Analyses on Trapezoidal Shape Repairs, Validating Both the Thermal and Mechanical Models with Experimental Results. Additionally, the Study Presents a Methodology for Creating a Toolpath Applicable to Both the DED Process and Abaqus CAE Software. the Findings Indicate that Employing a Pre-Heating Strategy Can Reduce Residual Stresses by over 70% Compared to No Pre-Heating. However, Pre-Heating …

Perceptions Of Factors From Mba Students At Small Regional Universities That Enhance, Improve, And Impact Individual Behavior As Measured By Environmental Working Scales, John Alpers

Masters Theses and Doctoral Dissertations

Organizations are continually trying to impact individual behavior so their employees will be motivated toward organizational objectives. The goal or intent of all organizations is to identify the impact the specific factors, engagement, leadership methods, and reward systems, can have on the motivation of employees toward organizational goals or objectives. The goal of this research is to identify if a relationship exists between the perceptions of Master of Business (MBA) students in regional universities toward the above-mentioned factors that improve, impact, and enhance their behavior toward organizational goals as indicated by each area’s impact on the work environment scale. Research …

Addressing Multimodal Transportation Needs Through Complete Streets Implementation, Eirini Stavropoulou, Nikiforos Stamatiadis, William Staats, Teng Wang, Reginald Souleyrette

Kentucky Transportation Center Research Report

Since the early 2000s, over 1,600 transportation agencies in the United States have adopted Complete Streets policies. Recently, the Kentucky Transportation Cabinet (KYTC) published its Complete Streets, Roads, and Highways Manual, which aims to implement a safe and equitable transportation system throughout the state, as well as a Complete Streets policy. The manual and policy offer guidance on integrating Complete Streets principles into road design, however, KYTC currently lacks tools or methods to evaluate how well specific projects address Complete Streets goals. This is problematic because systematic assessments are needed to effectively prioritize projects and allocate scarce funding. Based …

Developing Guidelines For The Use Of Lightweight Materials In Culvert Preservation, Charlie Sun, Kean H. Ashurst Jr.

Kentucky Transportation Center Research Report

This study addresses challenges that arise during highway embankment construction on road widening projects when additional fill is placed above existing culverts. Researchers conducted reduced-scale model laboratory tests to simulate culvert behavior under different loading conditions and to determine how well lightweight materials (LWMs) perform when subjected to changing loads. Testing showed that proximity of LWM to the culvert’s top surface strongly influences the magnitude of strain reductions or increases. Placing LWMs with relatively low elastic modulus closer to the culvert’s top surface led to reduced culvert ceiling strain and increased culvert wall strain. LWMs with relatively high elastic modulus …

Characterization And Analysis Of Supersonic Flow Through De Laval Nozzles At Varied Design Conditions, Sarah Baird

Doctoral Dissertations and Master's Theses

A combined numerical and experimental investigation of supersonic planar nozzles under different design conditions has been conducted. Supersonic planar nozzles are common geometries observed in supersonic wind tunnels and aircraft or rocket engines. For the important role they play in wind tunnel testing and aircraft propulsion, it is important to conduct a thorough numerical and experimental study to characterize their performance at different operating conditions. In this study, a de Laval nozzle was scanned to extract its contours and subsequently modeled to compare analytical and numerical performance expectations under design and off-design conditions. The nozzle was then installed in a …

Modeling Of Rotor Wake Vortex Dynamics And Interactions In Non-Homogenous Vertiport Environments, Garrison P. Shaw

Doctoral Dissertations and Master's Theses

The current research serves to analyze and study the effects ground forces can have on the thrust performance of a propeller in multiple different configurations. The current research utilizes an open source Computational Fluid Dynamics (CFD) software known as OpenFOAM to generate calculate and visualize these runs. The model used for this experiment is a hybrid model that employs both a Unsteady Reynolds-Averaged Navier-Stokes (URANS) and a detached eddy simulation using a hybrid Large Eddy Simulation (LES) via a KomegaSSTDDES model. This model serves to save computational time as well as allow for accurate results. The three cases run are …

Instead Of Holding, Joyce Safdiah

Gandy Dancer Archives

No abstract provided.

My Grandfather Taught Me How To Read, Diana Morley

Gandy Dancer Archives

No abstract provided.

Julia, Anna Lanze

Gandy Dancer Archives

No abstract provided.

Downstream, Jay Green

Gandy Dancer Archives

No abstract provided.

In My Free Time I Haunt The Hurricane House, Kashi Bakshani

Gandy Dancer Archives

No abstract provided.

Revolving Doors, What Have I Done?, Jenna Coburn

Gandy Dancer Archives

No abstract provided.

Things That Bother Me, Lauren Royce

Gandy Dancer Archives

No abstract provided.

Watershed/Waterspout, Kirry Kaufer

Gandy Dancer Archives

No abstract provided.

Thanksgiving Conversations, Madolley Donzo

Gandy Dancer Archives

No abstract provided.