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Full-Text Articles in Engineering

On The Pulsed Laser Ablation Of Metals And Semiconductors, Todd A. Van Woerkom Aug 2019

On The Pulsed Laser Ablation Of Metals And Semiconductors, Todd A. Van Woerkom

Theses and Dissertations

This dissertation covers pulsed laser ablation of Al, Si, Ti, Ge, and InSb, with pulse durations from tens of picosecond to hundreds of microseconds, fluences from ones of J/cm2 to over 10,000 J/cm2, and in ambient air and vacuum. A set of non-dimensional scaling factors was created to interpret the data relative to the laser and material parameters, and it was found that pulse durations shorter than a critical timescale formed craters much larger than the thermal diffusion length, and longer pulse durations created holes much shallower than the thermal diffusion length. Low transverse order Gaussian beams …


Targeted Germanium Ion Irradiation Of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistors, Melanie E. Mace Aug 2019

Targeted Germanium Ion Irradiation Of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistors, Melanie E. Mace

Theses and Dissertations

Microscale beams of germanium ions were used to target different locations of aluminum galliumnitride/gallium nitride (AlGaN/GaN) high electron mobility transistors (HEMTs) to determine location dependent radiation effects. 1.7 MeV Ge ions were targeted at the gap between the gate and the drain to observe displacement damage effects while 47 MeV Ge ions were targeted at the gate to observe ionization damage effects. Electrical data was taken pre, during, and post irradiation. To separate transient from permanent degradation, the devices were characterized after a room temperature anneal for at least 30 days. Optical images were also analyzed pre and post irradiation. …


Initial Development Of A Prototype Sensor Testbed For Fetal Monitoring, Christian Beauvais Aug 2019

Initial Development Of A Prototype Sensor Testbed For Fetal Monitoring, Christian Beauvais

Theses and Dissertations

The objective of this research is to design and manufacture a device that exhibits some of the bio-physiological signals relevant to fetal health monitoring. Currently, limited options exist for testing the performance of monitoring devices such as the tocodynamometer (TOCO) and electrocardiograph (ECG) that measure the bio-physiological signals of a woman and her fetus. Sensor designers need ways of generating and acquiring signals that do not carry the ethical burden of human testing. The development of such a device, as considered in this work, may involve using muscle wire or an inflatable tube as prospective foundations for simulating uterine contraction. …


Cislunar Trajectory Generation With Sun-Exclusion Zone Constraints Using A Genetic Algorithm And Direct Method Hybridization, Joshua A. Ostman Aug 2019

Cislunar Trajectory Generation With Sun-Exclusion Zone Constraints Using A Genetic Algorithm And Direct Method Hybridization, Joshua A. Ostman

Theses and Dissertations

Space missions to the Moon have received renewed interest in recent decades. Science missions continue to be sent to the Moon, and several space agencies have aspirations of establishing a human presence on the Moon. With the increased number of artificial objects in cislunar space, the problem of tracking these objects arises. Optical sensors are able to track these objects in deep space. However, optical sensors cannot track objects that are close to the Sun as viewed from the observer. This unobservable region is the Sun-exclusion zone (SEZ). This research attempts to create optimal Moon-Earth transfers which are completely in …


Point Defects In Lithium Gallate And Gallium Oxide, Christopher A. Lenyk Aug 2019

Point Defects In Lithium Gallate And Gallium Oxide, Christopher A. Lenyk

Theses and Dissertations

Electron paramagnetic resonance (EPR), Fourier-Transform Infrared spectroscopy (FTIR), photoluminescence (PL), thermoluminescence (TL), and wavelength-dependent TL are used to identify and characterize point defects in lithium gallate and β-gallium oxide doped with Mg and Fe acceptor impurities single crystals. EPR investigations of LiGaO2 identify fundamental intrinsic cation defects lithium (V−Li) and gallium (V2−Ga) vacancies. The defects’ principle g values are found through angular dependence studies and atomic-scale models for these new defects are proposed. Thermoluminescence measurements estimate the activation energy of lithium vacancies at Ea = 1.05 eV and gallium vacancies at Ea > 2 …


Operational Decision Making Under Uncertainty: Inferential, Sequential, And Adversarial Approaches, Andrew J. Keith Aug 2019

Operational Decision Making Under Uncertainty: Inferential, Sequential, And Adversarial Approaches, Andrew J. Keith

Theses and Dissertations

Modern security threats are characterized by a stochastic, dynamic, partially observable, and ambiguous operational environment. This dissertation addresses such complex security threats using operations research techniques for decision making under uncertainty in operations planning, analysis, and assessment. First, this research develops a new method for robust queue inference with partially observable, stochastic arrival and departure times, motivated by cybersecurity and terrorism applications. In the dynamic setting, this work develops a new variant of Markov decision processes and an algorithm for robust information collection in dynamic, partially observable and ambiguous environments, with an application to a cybersecurity detection problem. In the …


Laboratory Evaluation Of Cold In-Place Recycling Asphalt Mixtures Using A Balanced Mix Design, Ahmed Saidi Aug 2019

Laboratory Evaluation Of Cold In-Place Recycling Asphalt Mixtures Using A Balanced Mix Design, Ahmed Saidi

Theses and Dissertations

The objective of this research study is to present a procedure for designing Cold In-Place Recycling (CIR) mixtures through balancing cracking and rutting for these mixtures. Eight CIR mixtures were prepared using two recycling agents (foamed and emulsified asphalts), then cured for three days at two temperatures (140oF and 50oF), and compacted at two gyration levels (30 and 70 gyrations). The CIR mixtures were prepared at constant dosages of water and cement, 3% and 1%, respectively. Air void of each CIR performance test specimen was determined using the CoreLok device. The rutting susceptibility of these mixtures was then evaluated using …


Long-Term Performance Of Sustainable Pavements Using Ternary Blended Concrete With Recycled Aggregates, Seth M. Wagner Aug 2019

Long-Term Performance Of Sustainable Pavements Using Ternary Blended Concrete With Recycled Aggregates, Seth M. Wagner

Theses and Dissertations

The purposes of this study were to (a) design concrete pavement mixtures with recycled concrete aggregates using ternary blends of cementitious materials and a low water-to-binder ratio, (b) measure the fresh and hardened properties of the proposed concrete mixtures and (c) assess the long-term performance of the concrete implementing the use of recycled coarse aggregates. Preliminary investigation into ternary blend combinations via the compressive testing of mortar cubes and isothermal calorimetry was used to predict an optimal blend of cementitious material. Mixes using recycled concrete aggregates at varying replacement rates were tested for fresh and hardened properties using the proposed …


Studies Of Dislocation Density Quantification Via Cross-Correlation Ebsd, Samuel Searle Friedbaum Aug 2019

Studies Of Dislocation Density Quantification Via Cross-Correlation Ebsd, Samuel Searle Friedbaum

Theses and Dissertations

One conventional method for studying dislocations uses the Transmission Electron Microscope (TEM), a complex and expensive piece of equipment which requires extensive specimen preparation in order to thin the specimens to electron transparent thickness. Newer High Resolution Electron Backscatter Diffraction (HREBSD) methods of determining geometrically necessary dislocation content via cross-correlation promise to be able to produce estimates of the dislocation density of the sample over a larger area with considerably less preparation time and using a much more accessible instrument. However, the accuracy of the new EBSD technique needs more experimental verification, including consideration of possible changes in the specimen …


Turbinat E Hidrocentraleve Dhe Analiza E Efiçencës Tek Hidrocentralet E Vogla Dhe Të Mëdha, Edon Neziri Neziri Aug 2019

Turbinat E Hidrocentraleve Dhe Analiza E Efiçencës Tek Hidrocentralet E Vogla Dhe Të Mëdha, Edon Neziri Neziri

Theses and Dissertations

Energjia elektrike paraqet një nga burimet ekzistenciale të aktiviteteve dhe veprimtarisë njerëzore. Burimet energjetike janë të ndryshme, siç janë edhe mënyrat, pajisjet dhe stabilimentet për gjenerimin e saj. Shfrytëzimi i burimeve energjetike nga lëndë të ripërtëritshme, e në veçanti shfrytëzimi i burimeve hidrike përmes veprave inxhinierike të quajtura hidrocentrale sot paraqet një rëndësi të veçantë jo vetëm në shkallë vendi por edhe më gjerë. Ky punim diplome për përfundimin e nivelit të parë të studimeve (bachelor) ka për qëllim të nxjerrë në pah disa karakteristika të turbinave që përdoren në hidrocentrale, si dhe të jep rezultatet në lidhje me analizën …


Electrostatically Actuated Double Wall Carbon Nanotubes To Include Intertube Van Der Waals Forces, Ezequiel Juarez Ocanas Aug 2019

Electrostatically Actuated Double Wall Carbon Nanotubes To Include Intertube Van Der Waals Forces, Ezequiel Juarez Ocanas

Theses and Dissertations

This work deals with the amplitude-frequency and amplitude-voltage responses of parametric and primary resonances of electrostatically actuated double-walled carbon nanotubes (DWCNTs). Nonlinear forces acting on the DWCNT are intertube van der Waals and electrostatic forces. Soft AC excitation and small viscous damping are assumed. In coaxial vibration, the outer and inner carbon nanotubes move together (in-phase), maintaining their geometric concentricity; while in noncoaxial vibration, the CNTs move in opposite direction (out-of-phase). Modal coordinate transformation is formulated. The Harmonic Balance Method (HBM) is used to find the free response solutions of the DWCNT. The Reduced Order Model (ROM) method is also …


Parametric Study Of Selective Laser Alloying Of Elemental Titanium And Boron Powders Using An Automated Deposition Mechanism, Julian V. Gonzalez Aug 2019

Parametric Study Of Selective Laser Alloying Of Elemental Titanium And Boron Powders Using An Automated Deposition Mechanism, Julian V. Gonzalez

Theses and Dissertations

An automatic powder deposition and leveling mechanism was designed and constructed to assist in surface roughness experiments for titanium-boron samples. Previously developed energy models and x-ray diffraction analysis was used to confirm the creation of titanium diboride samples. To study TiB2 at different energy values, a 52 (2 factors, 5 levels) factorial design was used and carried out under an argon atmosphere, through the AM250 laser melting system. Two experimental runs were carried out and a total of 50 samples were assigned a surface roughness measurement through the Dektak XT profilometer. Graphically and with statistical analysis, the data was determined …


A Methodology To Measure The Impact Of Diversity On Cybersecurity Team Effectiveness, Caralea May Cornel Aug 2019

A Methodology To Measure The Impact Of Diversity On Cybersecurity Team Effectiveness, Caralea May Cornel

Theses and Dissertations

In recent years, the definition of cybersecurity professional has been diluted to include more individuals, particularly women, to be included. Depending on the definition used, women currently comprise between 11% and 25% of the cybersecurity workforce. While multiple studies have indicated the benefits to diverse teams, research in the cybersecurity area is lacking.This research proposes a framework that uses a modified escape-the-room gamified scenario to measure the effectiveness of cybersecurity teams in technical problem-solving. The framework presents two routes, incident response and penetration testing, the participants can choose. In a preliminary study, this framework is used to show the combination …


Simulation Framework And Potential Field Relocation For Systems Of Shared Autonomous Vehicles, Landon Blaine Wright Aug 2019

Simulation Framework And Potential Field Relocation For Systems Of Shared Autonomous Vehicles, Landon Blaine Wright

Theses and Dissertations

Shared autonomous vehicles present a significant opportunity to change the way that urban mobility is viewed by society. By providing a shared mobility platform at a cost lower than has previously been obtainable there are significant possibilites to enable a new era of mobility for consumers. This opportunity, however, comes with significant risks in the form of emissions and increased road usage. Understanding how the risks and benefits of shared autonomous vehicles can be balanced is crucial to be able to adequately prepare for their introduction. One of the primary ways to understand the interplay between the risks and benefits …


Characterization Of Dislocation - Grain Boundary Interactions Through Electron Backscatter Diffraction, Landon Thomas Hansen Aug 2019

Characterization Of Dislocation - Grain Boundary Interactions Through Electron Backscatter Diffraction, Landon Thomas Hansen

Theses and Dissertations

Further understanding of dislocation-GB interactions is critical to increasing the performance of polycrystalline metals. The research contained within this dissertation aims to further dislocation-GB interaction understanding through three research studies. First, the effect of noise in EBSPs on GND calculations was evaluated in order to improve dislocation characterization via HR-EBSD. Second, the evolution of GNDs and their effects on back stress was studied through experimental and computational methods applied to tantalum oligo specimens. Third, statistical analysis was used to evaluate grain parameters and current GB transmission parameters on their correlation with dislocation accumulation.


Distribution Of Tremorogenic Activity Among The Majorsuperficial Muscles Of The Upper Limb Insubjects With Essential Tremor, David Jordan Standring Aug 2019

Distribution Of Tremorogenic Activity Among The Majorsuperficial Muscles Of The Upper Limb Insubjects With Essential Tremor, David Jordan Standring

Theses and Dissertations

Optimized peripheral tremor suppression could address many limitations of surgical or medicinal treatments of Essential Tremor, however it is not well understood how the tremorogenic activity is distributed among the muscles of the upper limb, and therefore how to optimize such suppression. We recorded electromyographic (EMG) activity in the 15 major superficial muscles from the shoulder to the wrist while subjects performed postural and kinetic tasks similar to activities of daily living. We calculated the power spectral density and computed the total power in the tremor band (4"12 Hz) for each muscle, from which we determined the distribution of tremorogenic …


The Effect Of Subglottic Stenosis On The Aerodynamic, Acoustical, And Vibratory Output Of Synthetic Vocal Fold Models, Benjamin Allen Hilton Aug 2019

The Effect Of Subglottic Stenosis On The Aerodynamic, Acoustical, And Vibratory Output Of Synthetic Vocal Fold Models, Benjamin Allen Hilton

Theses and Dissertations

There are many conditions and diseases that affect voice production. One of these, subglottic stenosis (SGS), is characterized by a narrowing of the trachea near the cricotracheal junction. SGS causes dyspnea (labored breathing) and frequently surgery is necessary to eliminate the airway obstruction. SGS is also believed to adversely affect voice quality. While significant research has been conducted to study the effect of SGS on breathing, relatively few studies concerning its effect on voice production have been performed. The purpose of this research was to provide quantitative results concerning the predicted effects of SGS on vocal fold (VF) vibration and …


Comparison Of Heat Generation Models In Finite Element Analysis Of Friction Welding, Richard Verile Livingston Aug 2019

Comparison Of Heat Generation Models In Finite Element Analysis Of Friction Welding, Richard Verile Livingston

Theses and Dissertations

Finite element models of friction welding can be used to estimate internal conditions of welds which are useful for weld analysis and developing experimental welding procedures. Many modeling techniques are used to accomplish these goals, each with relative strengths and weaknesses. A comparative analysis of friction welding models using different heat generation methods is presented. The three different heat generation methods examined were viscoplastic friction, constant steady-state generation, and experimentally measured power data. The models were compared against each other using three output measurements: temperature, axial force, and upset. The friction model predicted temperatures within 40 degrees C. Temperature accuracy …


Significance Of The Rates Of Atmospheric Deposition Around Utah Lake And Phosphorus-Fractionation Of Local Soils, Joshua Glen Reidhead Aug 2019

Significance Of The Rates Of Atmospheric Deposition Around Utah Lake And Phosphorus-Fractionation Of Local Soils, Joshua Glen Reidhead

Theses and Dissertations

Eutrophic Utah Lake receives a large nutrient load from a variety of sources, includingtreated wastewater discharges, runoff and tributaries, recycling from bottom sediments andAtmospheric Deposition (AD). AD was the focus of this study and was comprised of twocomplementary parts. First was a study of nitrogen and phosphorus depositions from theatmosphere, and second was a study of phosphorous as contained in soils near Utah Lake viafractionation methods.The soil samples were found to contain approximately 1,000 mg-P/kg soil for totalphosphorus (TP). A separate phosphorus (P) fractionation gave slightly higher values, excludingthe residual P, we are 95% confident that one gram of sample …


A Study Of Human Balance And Coordination Using A Head Mounted Display, Daniel Gracia De Luna Aug 2019

A Study Of Human Balance And Coordination Using A Head Mounted Display, Daniel Gracia De Luna

Theses and Dissertations

Virtual Reality (VR) is growing with new technologies and applications. The new technologies help the user to feel more immersed in virtual environments, but interaction and immersion is an area that has not been well studied. Immersion is the feeling and reaction of users while they are in a virtual environment. This investigation is focused on the study of the human balance and coordination when human subjects are inside a virtual environment. Over 60 subjects are studied under an experiment, where their trajectory is captured and analyzed to identify possible differences or similitudes between male and female subjects.


Cybersecurity Education In Utah High Schools: An Analysis And Strategy For Teacher Adoption, Cariana June Cornel Aug 2019

Cybersecurity Education In Utah High Schools: An Analysis And Strategy For Teacher Adoption, Cariana June Cornel

Theses and Dissertations

The IT Education Specialist for the USBE, Brandon Jacobson, stated:I feel there is a deficiency of and therefore a need to teach Cybersecurity.Cybersecurity is the “activity or process, ability or capability, or state whereby information and communications systems and the information contained therein are protected from and/or defended against damage, unauthorized use or modification, or exploitation” (NICE, 2018). Practicing cybersecurity can increase awareness of cybersecurity issues, such as theft of sensitive information. Current efforts, including but not limited to, cybersecurity camps, competitions, college courses, and conferences, have been created to better prepare cyber citizens nationwide for such cybersecurity occurrences. In …


Predicting Hardness Of Friction Stir Processed 304l Stainless Steel Using A Finite Element Model And A Random Forest Algorithm, Tyler Alan Mathis Aug 2019

Predicting Hardness Of Friction Stir Processed 304l Stainless Steel Using A Finite Element Model And A Random Forest Algorithm, Tyler Alan Mathis

Theses and Dissertations

Friction stir welding is an advanced welding process that is being investigated for use in many different industries. One area that has been investigated for its application is in healing critical nuclear reactor components that are developing cracks. However, friction stir welding is a complicated process and it is difficult to predict what the final properties of a set of welding parameters will be. This thesis sets forth a method using finite element analysis and a random forest model to accurately predict hardness in the welding nugget after processing. The finite element analysis code used and ALE formulation that enabled …


Pressurized Combustion Product Temperature Measurement Using Integrated Spectral Band Ratios, Scott Cutler Egbert Aug 2019

Pressurized Combustion Product Temperature Measurement Using Integrated Spectral Band Ratios, Scott Cutler Egbert

Theses and Dissertations

With increasing global power demands, there is a growing need for the clean and efficient use of fossil fuel resources. Gas turbine engines are a commonly used means for generating power; from the propulsion of aircraft to electricity on municipal grids. Measuring the temperature within a turbine combustor or at a turbine inlet could provide numerous advantages related to engine control, durability, efficiency, and emissions and yet this relatively straightforward task has eluded turbine engine manufacturers, primarily because of the high temperatures and pressures, harsh environment, and limited access. Optical emissions measurements are of particular interest for this task as …


An Experimental Study Of Thrust Augmentation With Asymmetrical Nozzle Driven Pulsed Ejector, Orlando Rodriguez Aug 2019

An Experimental Study Of Thrust Augmentation With Asymmetrical Nozzle Driven Pulsed Ejector, Orlando Rodriguez

Theses and Dissertations

With the emergence of V/STOL vehicles and unmanned aircrafts has come the resurgence of thrust augmentation through an ejector. The use of an ejector has many benefits such as being lightweight and simple design to manufacture. In this study a hot steady jet and a cold steady/unsteady jet was tested. The hot steady jet was produced by a JetCAT PX-180 rxi with a two-inch diameter nozzle exit. The hot steady jet was compared to the cold free steady and unsteady cases. The cold jet was tested under free steady and unsteady condition, as well as steady and unsteady ejector conditions. …


Assessment Of Some Of The Common Practices Used In Scheduling Highway Projects, Jennifer Reyes Aug 2019

Assessment Of Some Of The Common Practices Used In Scheduling Highway Projects, Jennifer Reyes

Theses and Dissertations

There are several factors documented in the literature that can affect the accuracy of estimated project durations in highway construction, such as weather, location, and soil conditions. Recently, the Texas Department of Transportation (TxDOT) raised a concern regarding some of the practices used when estimating the contract time for projects. This research presents an assessment of the effect that two practices identified have on the estimated project duration. These two practices include: 1) the estimated lead/lag times in project schedules and 2) scheduling with only critical or controlling activities. The effect of these practices is measured, primarily, by using four …


Isogeometric Bezier Dual Mortaring And Applications, Di Miao Aug 2019

Isogeometric Bezier Dual Mortaring And Applications, Di Miao

Theses and Dissertations

Isogeometric analysis is aimed to mitigate the gap between Computer-Aided Design (CAD) and analysis by using a unified geometric representation. Thanks to the exact geometry representation and high smoothness of adopted basis functions, isogeometric analysis demonstrated excellent mathematical properties and successfully addressed a variety of problems. In particular, it allows to solve higher order Partial Differential Equations (PDEs) directly omitting the usage of mixed approaches. Unfortunately, complex CAD geometries are often constituted by multiple Non-Uniform Rational B-Splines (NURBS) patches and cannot be directly applied for finite element analysis.parIn this work, we presents a dual mortaring framework to couple adjacent patches …


Development And Analysis Of 3d-Printed Synthetic Vocal Fold Models, Ryan Gregory Romero Aug 2019

Development And Analysis Of 3d-Printed Synthetic Vocal Fold Models, Ryan Gregory Romero

Theses and Dissertations

Vocal fold models are valuable for studying voice production. They provide an alternative method of studying the mechanics of the voice that does not require in vivo experimentation or the use of excised human or animal tissue. In this thesis, a new method of creating vocal fold models through additive manufacturing is described. The purpose of this research was to reduce model fabrication time, to decrease the number of model failures during manufacturing, and to lay the foundation for creating models with more lifelike geometric and material properties. This research was conducted in four stages. First, a suitable silicone additive …


Improving And Modeling Bacteria Recovery In Hollow Disk System, Clifton Anderson Aug 2019

Improving And Modeling Bacteria Recovery In Hollow Disk System, Clifton Anderson

Theses and Dissertations

Identifying antibiotic resistance in blood infections requires separating bacteria from whole blood. A hollow spinning disk rapidly removes suspended red blood cells by leveraging hydrodynamic differences between bacteria and whole blood components in a centrifugal field. Once the red cells are removed, the supernatant plasma which contains bacteria is collected for downstream antibiotic testing. This work improves upon previous work by modifying the disk design to maximize fractional plasma recovery and minimize fractional red cell recovery. V-shaped channels induce plasma flow and increase fractional plasma recovery. Additionally, diluting a blood sample spiked with bacteria prior to spinning it increased the …


Energy Harvesting Techniques To Power Onboard Railway Bearing Condition Monitoring Systems, Jacob Nathaniel Bensen Aug 2019

Energy Harvesting Techniques To Power Onboard Railway Bearing Condition Monitoring Systems, Jacob Nathaniel Bensen

Theses and Dissertations

Limitations of the standard wayside hotbox detection system as a method to identify failing railway bearings severely inhibit the reliability and safety of rail transport. An onboard bearing condition monitoring system would address and ameliorate the issues present in the current detection system. The onboard system would provide more frequent and reliable information regarding bearing condition. For the system to succeed in reducing maintenance time and preventing bearing failure, a method of providing the system with sufficient energy to power its instrumentation is necessary. The instrumentation location environment poses a significant challenge. The device must be placed on the steel …


Improving The Single Event Effect Response Of Triple Modular Redundancy On Sram Fpgas Through Placement And Routing, Matthew Joel Cannon Aug 2019

Improving The Single Event Effect Response Of Triple Modular Redundancy On Sram Fpgas Through Placement And Routing, Matthew Joel Cannon

Theses and Dissertations

Triple modular redundancy (TMR) with repair is commonly used to improve the reliability of systems. TMR is often employed for circuits implemented on field programmable gate arrays (FPGAs) to mitigate the radiation effects of single event upsets (SEUs). This has proven to be an effective technique by improving a circuit's sensitive cross-section by up to 100x. However, testing has shown that the improvement offered by TMR is limited by upsets in single configuration bits that cause TMR to fail.This work proposes a variety of mitigation techniques that improve the effectiveness of TMR on FPGAs. These mitigation techniques can alter the …