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Evaluation, Rating, And Numerical Modeling Of A Shock Mitigation Seat For High-Speed Craft Based On Laboratory Single Impact Testing, Darren Benn

UNLV Theses, Dissertations, Professional Papers, and Capstones

High-speed craft (HSC) are utilized in military and para-military maneuvers that are usually conducted in harsh environments. The Special Warfare Combatant-craft Crewmen (SWCC), a sub-unit of the United States Naval Special Warfare Command (NAVSOC), use an advanced HSC, known as the Combatant Craft Assault, to conduct coastal patrol and interdiction, and for infiltration and exfiltration of Navy SEALs. The United States Coast Guard, and the Drug Enforcement Agency (DEA), employ HSC for maritime patrol and to pursue ‘go-fast’ boats operated by contraband runners. In most of these intense applications, the mode of operation of the HSC results in planing. Planing …

Seasonal Climate And Environmental Conditions Associated With Physiological Variations Of Southwestern United States Pines, Taylor Brewer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Juvenile and adult conifers in the southwestern United States are vulnerable to a range of different abiotic and biotic factors, yet it is unclear how their stress tolerance varies across environments. Predicted increases in the frequency and intensity of disturbance as well as greater climate and weather variability across the region highlight the potential for differential physiological responses across tree species and populations. This thesis focuses on two physiologic mechanisms, hydraulic vulnerability and mortality, that could be altered by climate change in two broadly distributed southwestern United States conifers: ponderosa pine and pinyon pine.

In chapter 2, I measured the …

Exploring Intention Mapping And Action In Pursuit Of Emotional Storytelling For Musicians, Douglas Carpenter

UNLV Theses, Dissertations, Professional Papers, and Capstones

This document presents a novel approach to music education by integrating acting pedagogies, specifically the concepts of "Intention" and "Action," to enhance the expressive capabilities of musicians. Rooted in the methodologies of Konstantin Stanislavski, Sanford Meisner, and Michael Chekhov, this research seeks to bridge the gap between traditional music education, which often emphasizes technical execution, and the need for emotional expressivity and storytelling in musical performances.

The role of the musician as a 'human instrument,' capable of conveying complex human emotions and narratives through music is explored in this document. Drawing from acting techniques, the document proposes methods to help …

The Influence Of Bihemispheric Transcranial Direct Current Stimulation On Muscle Fatigue, Ananya Singh Chauhan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Unilateral transcranial direct current stimulation (tDCS) using two electrodes placed over the primary motor cortex (M1) and the contralateral supraorbital (SO) region (M1-SO montage) has been shown to decrease the progression of muscle fatigue. The primary purpose was to determine the impact of bihemispheric tDCS (bi-tDCS) applied over the left and right M1s (bi-tDCS) on the time to task failure (TTF) of a precision-grip task. The study implemented a double-blind, randomized, SHAM-controlled, within-subjects design. A total of 20 participants performed two experimental sessions (bi-tDCS and SHAM conditions) separated by a one-week washout. During each experimental session, a fatiguing isometric contraction …

Understanding Stress And Coping Among Adults In The United States During The Covid-19 Pandemic, Jocy-Anna Chevalier

UNLV Theses, Dissertations, Professional Papers, and Capstones

Since the COVID-19 pandemic started, individuals in the United States (U.S.) and across the globe have experienced unprecedented levels of stress. The purpose of this study is to understand the stress experienced among adults in the U.S. and which coping processes affect their overall emotional well-being. Guided by Lazarus and Folkman’s (1987) Transactional Model of Stress and Coping (TMSC), this study conducted a secondary data analysis (n=404) of adults across the U.S who completed an online survey examining their experiences with stress and coping. A Pearson correlation was utilized to explore the relationship between stress and depressive symptoms. Paired samples …

The Influence Of Bilateral Dual Source Transcranial Direct Current Stimulation On The Progression Of Muscle Fatigue, Eliza Clinton

UNLV Theses, Dissertations, Professional Papers, and Capstones

Transcranial direct current stimulation (tDCS) applied unilaterally to the primary motor cortex (M1) can significantly prolong the time to task failure (TTF) of a fatiguing contraction. The primary purpose of the study was to examine the influence of bilateral dual source tDCS (dstDCS) applied over the left and right M1s (ds-tDCS) on the TTF of a precision grip task. This was accomplished through the utilization of a double-blind, randomized, SHAM-controlled, within-subjects design. Fourteen participants completed two experiments (ds-tDCS and SHAM stimulation conditions) with a seven-day washout period between sessions. Each experiment involved the performance of a sustained isometric fatiguing contraction …

Using Student Voices To Inform Educational Reform: Exploring High School Educational Desires To Improve Curricular Decisions, Anna Colquitt

UNLV Theses, Dissertations, Professional Papers, and Capstones

In the education system, the integration of student perspectives into effective pedagogical strategies is gaining momentum. This dissertation delves into the concept of 'Student Voice' and its role in shaping educational frameworks. Recognizing the growing gap in soft skill proficiency among newly recruited employees, contrasted with the emphasis on hard skills within current educational standards, this study analyzes what those skill gaps are in the education and what skills students perceive are necessary to integrate into a high school education to better prepare students for life, the workforce, and higher education. Focused on recent high school graduates in Nevada, the …

Investigating Controls On Temporal And Spatial Variation Of Dissolved Uranium At Springs In Horn Creek Drainage, Grand Canyon National Park, Arizona, Usa, Collin Davidson

UNLV Theses, Dissertations, Professional Papers, and Capstones

Groundwater is a critical resource in the Grand Canyon, providing water to local communities, millions of annual visitors, and ecosystems. One major concern for this critical resource is the potential for uranium contamination in conjunction with uranium mining efforts. Upper Horn Bedrock Spring (UHB) in the Horn Creek drainage of the Grand Canyon sits below the oldest uranium mine in the region, Orphan Lode mine. UHB spring contains the highest concentration of dissolved uranium in the region, eclipsing the Maximum Contaminant Level (MCL) set by the USEPA by an order of magnitude on average. This research and recent collaboration with …

Experiment Development And Validation Of A Granular Jamming Robotic Gripper, Jacob R. Dowd

UNLV Theses, Dissertations, Professional Papers, and Capstones

A granular jamming gripper (GJG) is widely known as a Universal Gripper because of the wide range of objects that it can grasp and the simplicity of control, design, and manufacturing. Despite multitude of research improving the GJG, here, we focus on the base version of the GJG and attempt to glean the range of objects that it may reliably grasp. Despite the limited range of objects, which were a sphere, rectangular prism, and cylinder, we gleaned geometric properties as it relates to successful and unsuccessful grasping. This was based on the two types of testing: push and pull testing …

Causal Attribution Tendencies Of Early Childhood Practitioners And The Efficacy Of Attribution Retraining, Alex J. Faucheux

UNLV Theses, Dissertations, Professional Papers, and Capstones

Early childhood practitioners frequently attempt to identify the cause of outcomes experienced by their learners. This is sometimes referred to as causal attribution. Causal attribution may be affected by prior success and failure of a learner, the amount of effort exerted by the learner, the ability level of the learner, and knowledge of any disability associated with the learner, all of which can be considered controllable or uncontrollable, stable or unstable, and internal or external (Weiner, 1986; Woodcock & Vialle, 2011). As practitioners attribute cause to outcomes, they start to develop attributional tendencies; these tendencies, along with the cues and …

An Analysis Of Truancy Causes And Prevention Programming In Clark County, Nevada, Jennifer Ashley Fletcher

UNLV Theses, Dissertations, Professional Papers, and Capstones

In the United States truancy prevention is lacking two key elements to success; research that explains the causes of truancy and empirical evidence for best practices of truancy prevention. Truancy has been a problem in academics since the early 1900’s, when truancy became illegal. Since then, truancy rates have continued to see a steady increase, and today approximately 10% of public school students in the United States are truant every day (Maynard et al., 2017). To combat this problem, research needs to be conducted to understand why truancy happens. However, there is a severe lack of research on this topic; …

The Effect Of Dual Source Premotor Cortex Transcranial Direct Current Stimulation On Muscle Fatigue In Hand Muscles, Valentino Contini

UNLV Theses, Dissertations, Professional Papers, and Capstones

Single source transcranial direct current stimulation (tDCS) has been shown to increase the time to task failure (TTF) fatiguing contractions when applied to the dorsolateral prefrontal cortex (DLPFC) and to the primary motor cortex (M1). The primary purpose was to determine whether dual source tDCS delivered bilaterally over the premotor cortices (pmc-tDCS) could increase the TTF of a fatiguing contraction performed by hand muscles. A double-blind, randomized, SHAM-controlled, crossover design was used for this study with each participant performing two experimental sessions held on separate days a week apart. The only difference between the two sessions was the type of …

Remote Detection Of Leaks In High Level Waste Storage Tanks, Hunter Frey

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this research was to characterize three devices potentially capable of remotely detecting signatures of a leak from high-level waste (HLW) storage tanks, specifically ones found at the Savannah River Site and the Hanford Site. The hazard HLW found within these tanks include ¹³⁷Cs, a gamma-ray emitter, and ⁹⁰Sr, an electron emitter leading to heat generation. These pose health risks to the personnel and maintenance problems and environmental safety issues if released to the environment. Additionally, pinpointing the location of a leak is a task that could lead to the mitigation of excess waste leaking from …

Predicting The Response Of An Underactuated, 3d Printed Prosthetic Hand, Lucas Gallup

UNLV Theses, Dissertations, Professional Papers, and Capstones

The continuing need for hand prostheses has led to incredible developments in this area. However, due to the cost of the most sophisticated models, it is vital to develop simpler, low-cost, underactuated prostheses that can be produced rapidly. 3D printing is an important tool to achieve this goal. In particular, the 3D printed Flexy-Hand 2 has been one of the most common low-cost designs. A key feature of the Flexy-Hand 2 is its use of tendons and thermoplastic polyurethane (TPU) for joints that are strong and flexible. TPUs, however, lack a thorough understanding of their mechanical behavior, which makes it …

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 …