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Articles 781 - 810 of 4850

Full-Text Articles in Engineering

Precision Maritime Landing Of Autonomous Multirotor Aircraft With Real-Time Kinematic Gnss, Matthew Kent Rydalch Jul 2021

Precision Maritime Landing Of Autonomous Multirotor Aircraft With Real-Time Kinematic Gnss, Matthew Kent Rydalch

Theses and Dissertations

In this thesis two methods were developed for precise maritime landing of an autonomous multirotor aircraft based on real-time kinematic (RTK) Global Navigation Satellite System (GNSS). The first method called RTK-localized method (RLM) uses RTK GNSS measurements to localize a sea vessel and execute the landing. RLM was demonstrated outdoors in hardware and landed on a physically simulated boat called a mock-boat with an average landing error of 9.7 cm. The mock-boat was actuated to have boat-like motion and a forward velocity of ~2 m/s. This method showed that accurate landing is possible with RTK GNSS as the primary means …


Influencing Perceptions Of Stem Through The Best Stem Books List, Scott Bartholomew, Alexia Seymour Jul 2021

Influencing Perceptions Of Stem Through The Best Stem Books List, Scott Bartholomew, Alexia Seymour

Faculty Publications

One day, while discussing engineering and science as potential career options with a female student, we opened a search engine and typed in “engineer” and “scientist.” However, on the first pages of image results, only one female appeared for engineering and only a few females appeared for “scientist” (see Figure 1). This disparity was disturbing—if this student never saw another person like her filling careers in STEM fields, would she ever “picture herself” in those fields?


A New Method Of Measuring Flow Stress For Improved Modeling Of Friction Stir Welding, David John Prymak Jun 2021

A New Method Of Measuring Flow Stress For Improved Modeling Of Friction Stir Welding, David John Prymak

Theses and Dissertations

Deficiencies in friction stir welding (FSW) numerical modelling are identified. Applicability of flow stress data derived from hot compression, hot torsion, and split Hopkinson bar testing methods is assessed. A new method of measuring flow stresses in the stir zone of a friction stir welding tool is developed. This test utilizes a non-consumable flat-faced cylindrical tool of different geometries that induces a vertical and rotational load on the material of interest. A constant vertical load and rpm value is used for each test yielding the resulting motor torque and temperature generation to define the material response. Experimental samples are cross-sectioned, …


Zero-Energy Tuning Of Silicon Microring Resonators Using 3d Printed Microfluidics And Two-Photon Absorption Induced Photoelectrochemical Etching Of Silicon, Kevin Eugene Larson Jun 2021

Zero-Energy Tuning Of Silicon Microring Resonators Using 3d Printed Microfluidics And Two-Photon Absorption Induced Photoelectrochemical Etching Of Silicon, Kevin Eugene Larson

Theses and Dissertations

This thesis presents a novel method of modulating silicon photonic circuits using 3D printed microfluidic devices. The fluids that pass through the microfluidic device interact directly with the silicon waveguides. This method changes the refractive index of the waveguide cladding, thus changing the effective index of the system. Through using this technique we demonstrate the shift in resonant wavelength by a full free spectral range (FSR) by increasing the concentration of the salt water in the microfluidic device from 0% to 10%. On a 60 μm microring resonator, this equals a resonant wavelength shift of 1.514 nm when the index …


High-Speed Image Classification For Resource-Limited Systems Using Binary Values, Taylor Scott Simons Jun 2021

High-Speed Image Classification For Resource-Limited Systems Using Binary Values, Taylor Scott Simons

Theses and Dissertations

Image classification is a memory- and compute-intensive task. It is difficult to implement high-speed image classification algorithms on resource-limited systems like FPGAs and embedded computers. Most image classification algorithms require many fixed- and/or floating-point operations and values. In this work, we explore the use of binary values to reduce the memory and compute requirements of image classification algorithms. Our objective was to implement these algorithms on resource-limited systems while maintaining comparable accuracy and high speeds. By implementing high-speed image classification algorithms on resource-limited systems like embedded computers, FPGAs, and ASICs, automated visual inspection can be performed on small low-powered systems. …


Behavior Of Unreinforced Lightweight Cellular Concrete Backfill For Reinforced Concrete Retaining Walls, Ryan Jeffrey Wilkinson Jun 2021

Behavior Of Unreinforced Lightweight Cellular Concrete Backfill For Reinforced Concrete Retaining Walls, Ryan Jeffrey Wilkinson

Theses and Dissertations

Lightweight cellular concrete (LCC) is a mixture of cement, water and foam, with a density less than 50 pcf. This material is being used increasingly often in a variety of construction applications due to its self-leveling, self-compacting, and self-consolidating properties. LCC may be used as a backfill or structural fill in areas where traditional granular backfill might normally be used. This material may be especially advantageous in areas where the underlying soil may not support the weight of a raised earth embankment. Testing on the behavior of LCC when used as backfill behind retaining walls is relatively limited. The effects …


Understanding Quote-Tweet Usage During The Covid-19 Pandemic, David Hardy Bean Jun 2021

Understanding Quote-Tweet Usage During The Covid-19 Pandemic, David Hardy Bean

Theses and Dissertations

The Covid-19 pandemic first entered the international news cycle with mixed levels of concern. How did people across the globe react to first encounters with this virus? For many it was like seeing for the first time the spewing ash of a volcano, or the receding tides of a tsunami. Many reacted with disbelief, not knowing the proper course of action for themselves or for their community. This study explores the topics of discussion and reactions to the pandemic through the lens of quote-tweets--from the initial confusion and disbelief to the eventual politicization, economic closures, and reopening events. Quote-tweets are …


A Framework For Assessing And Designing Human Annotation Practices In Human-Ai Teaming, Suzanne Ashley Stevens Jun 2021

A Framework For Assessing And Designing Human Annotation Practices In Human-Ai Teaming, Suzanne Ashley Stevens

Theses and Dissertations

This thesis work examines how people accomplish annotation tasks (i.e., labelling data based on content) while working with an artificial intelligence (AI) system. When people and AI systems work together to accomplish a task, this is referred to as human-AI teaming. This study reports on the results of an interview and observation study of 15 volunteers from the Washington DC area as the volunteers annotated Twitter messages (tweets) about the COVID-19 pandemic. During the interviews, researchers observed the volunteers as they annotated tweets, noting any needs, frustrations, or confusion that the volunteers expressed about the task itself or when working …


Effective Temperature Control For Industrial Friction Stir Technologies, Arnold David Wright Jun 2021

Effective Temperature Control For Industrial Friction Stir Technologies, Arnold David Wright

Theses and Dissertations

Systematic investigation of the Friction Stir Welding (FSW) process shows that a fixed rotational velocity and feed rate may not yield uniform mechanical properties along the length of a weldment. Nevertheless, correlations between process parameters and post-weld material properties have successfully demonstrated that peak temperature and cooling rate drive post-weld properties. There have been many reported methodologies for controlling friction stir welding, with varying degrees of cost to implement and effectiveness. However, comparing data from uncontrolled FSW of AA 6111-T4 sheet with controlled FSW at temperatures ranging from 375 °C to 450 °C demonstrates that a simplified methodology of a …


Certifying Computer Forensics Skills, Michael Charles Watson Jun 2021

Certifying Computer Forensics Skills, Michael Charles Watson

Theses and Dissertations

Computer forensics is an ever-growing technological field of complexity and depth. Individuals must strive to keep learning and growing their skills as they help combat cybercrime throughout the world. This study attempts to establish a method of evaluating conceptual expertise in computer forensics to help indicate whether or not an individual understands the five basic phases of computer forensics: preparation, seizure of evidence, acquisition of data, analysis of data, and reporting the findings of the analysis. A survey was presented to a university class of 30 students taking a computer forensics course and as well as posted online asking computer …


Application Of Compositional Data Analysis To Determine The Effects Of Heating Mode, Moisture Status And Plant Species On Pyrolysates, David R. Weise, Thomas H. Fletcher, Mohammad-Saeed Safdari, Elham Amini, Javier Palarea-Albaladejo Jun 2021

Application Of Compositional Data Analysis To Determine The Effects Of Heating Mode, Moisture Status And Plant Species On Pyrolysates, David R. Weise, Thomas H. Fletcher, Mohammad-Saeed Safdari, Elham Amini, Javier Palarea-Albaladejo

Faculty Publications

Pyrolysate gas mixtures are multivariate and relative in nature. Statistical techniques applied to these data generally ignore their relative nature. Published data for permanent gases (CO, CO2, H2, CH4) and tars produced by pyrolysing 15 wildland fuels were reanalysed using compositional data analysis techniques. Mass and mole fractions were compositionally equivalent. Plant species, moisture status and heating mode effects on compositional balances formed from subsets of pyrolysates were tested. Plant species affected the amount of phenol, primary and secondary/tertiary tars relative to permanent gases and relative amounts of single- and multi-ring compounds. Plant moisture status affected the amount of CO …


Turtle: A Fault Injection Platform For Sram-Based Fpgas, Corbin Alma Thurlow Jun 2021

Turtle: A Fault Injection Platform For Sram-Based Fpgas, Corbin Alma Thurlow

Theses and Dissertations

SRAM-Based FPGAs provide valuable computation resources and reconfigurability; however, FPGA designs can fail during operation due to ionizing radiation. As an SRAM-based device, these FPGAs store operation-critical information in configuration RAM, or CRAM. Testing, through radiation tests, can be performed to prove the effectiveness of SEU mitigation techniques by comparing the SEU sensitivity of an FPGA design with and without the mitigation techniques applied. However, radiation testing is expensive and time-consuming. Another method for SEU sensitivity testing is through fault injection. This work describes a low-cost fault injection platform for evaluating the SEU sensitivity of an SRAM-based FPGA design by …


Software Defined Radio Short Range Radar, Nicholas Everett Kohls Jun 2021

Software Defined Radio Short Range Radar, Nicholas Everett Kohls

Theses and Dissertations

High cost is a current problem with modern radar systems. Software-defined radios (SDRs) offer a possible solution for low-cost customizable radar systems. An SDR is a radio communi- cation system where, instead of the traditional radio components implemented in hardware, many of the components are implemented in software on a computer or embedded system. Although SDRs were originally designed for wireless communication systems, the firmware of an SDR can be configured into a radar system. With new companies entering the market, various types of low- cost SDRs have emerged. This thesis explores the use of a LimeSDR-Mini in a short-range …


Regional Water Quality Data Viewer Tool: An Open-Source To Support Research Data Access, Danisa Dolder Jun 2021

Regional Water Quality Data Viewer Tool: An Open-Source To Support Research Data Access, Danisa Dolder

Theses and Dissertations

Water quality data collection, storage, and access is a difficult task and significant work has gone into methods to store and disseminate these data. We present a tool to disseminate research in a simple method that does not replace but extends and leverages these tools. In the United States, the federal government maintains two systems to fill that role for hydrological data: the U.S. Geological Survey (USGS) National Water Information System (NWIS) and the U.S. Environmental Protection Agency (EPA) Storage and Retrieval System (STORET), since superseded by the Water Quality Portal (WQP). The Consortium of the Universities for the Advancement …


Effects Of Whole Body Vibration On Inhibitory Control Processes, Bennett Alan Mortensen Jun 2021

Effects Of Whole Body Vibration On Inhibitory Control Processes, Bennett Alan Mortensen

Theses and Dissertations

Vibrations are often experienced in the workplace and may influence performance and executive function. Research has shown that vibrations may have an affect effect on drowsiness and tests related to inhibitory control. Previous work investigating whole body vibrations (WBV) and their effect was evaluated to inform the decisions for this study. WBV effects on cognitive abilities were examined and the different tests used in these studies were identified and compared. Electroencephalogram (EEG) and event related potentials (ERP) were selected to be used to measure inhibitory and cognitive processes. The N2 ERP, which reflects inhibitory control processes, was examined as well …


Dynamic Body Armor Shape Sensing Using Fiber Bragg Gratings And Photoassisted Silicon Wire-Edm Machining, Ivann Civi Lomas-E Velasco Jun 2021

Dynamic Body Armor Shape Sensing Using Fiber Bragg Gratings And Photoassisted Silicon Wire-Edm Machining, Ivann Civi Lomas-E Velasco

Theses and Dissertations

In this thesis, a method to improve survivability is developed for fiber Bragg gratings under high velocity impact in dynamic body armor shape sensing applications by encasing the fiber in silicone. Utilizing the slipping of the fiber within the silicone channel, a proportionality relationship between the strain of the fiber to the acceleration of the impacting projectile is found and is used to obtain the rate of the back-face deformation. A hybrid model is developed to handle errors caused by the stick-slip of the fiber by fitting an inverse exponential to stuck sections found in a captured strain profile and …


Estimation And Simulation Of Daily Activity Patterns For Individuals Using Wheelchairs, Nathan John Lant Jun 2021

Estimation And Simulation Of Daily Activity Patterns For Individuals Using Wheelchairs, Nathan John Lant

Theses and Dissertations

Individuals who use wheelchairs or who have other mobility challenges often are unable to access modern mobility systems "“ including application-based ride hailing and on-demand microtransit. Even designing a system targeted at these users is challenging, given the limited prior analysis of their travel behavior and activity patterns. Simulation tools are used by cities around the world to understand novel and complex transportation systems, yet few are including the needs of users with disabilities in these simulation studies. This thesis examines the travel patterns of wheelchair users from the 2017 National Household Travel Survey and presents a model of daily …


Reliable Mode Tracking In Gradient-Based Optimization Frameworks With Flutter Constraints, Taylor Mcdonnell, Andrew Ning Jun 2021

Reliable Mode Tracking In Gradient-Based Optimization Frameworks With Flutter Constraints, Taylor Mcdonnell, Andrew Ning

Faculty Publications

In order to construct mode-specific flutter constraints for use in gradient-based multidisciplinary design optimization frameworks, mode tracking must be used to associate the current iteration’s modes with the modes corresponding to each constraint function. Existing mode tracking methods, however, do not provide a method by which to ensure the accuracy of mode associations, making them unsuitable for use in situations where obtaining correct mode associations is critical. To remedy this issue, a new mode tracking method is presented which incorporates backtracking logic in order to maintain an arbitrarily high degree of confidence in mode correlations during gradient-based optimization and/or during …


Small-Target Detection And Observation With Vision-Enabled Fixed-Wing Unmanned Aircraft Systems, Hayden Matthew Morgan May 2021

Small-Target Detection And Observation With Vision-Enabled Fixed-Wing Unmanned Aircraft Systems, Hayden Matthew Morgan

Theses and Dissertations

This thesis focuses on vision-based detection and observation of small, slow-moving targets using a gimballed fixed-wing unmanned aircraft system (UAS). Generally, visual tracking algorithms are tuned to detect motion of relatively large objects in the scene with noticeably significant motion; therefore, applications such as high-altitude visual searches for human motion often ignore target motion as noise. Furthermore, after a target is identified, arbitrary maneuvers for transitioning to overhead orbits for better observation may result in temporary or permanent loss of target visibility. We present guidelines for tuning parameters of the Visual Multiple Target Tracking (Visual MTT) algorithm to enhance its …


Exploring The Performance Impacts Of Harmful Fpga Configurations, Tanner Gaskin May 2021

Exploring The Performance Impacts Of Harmful Fpga Configurations, Tanner Gaskin

Theses and Dissertations

In this work a new technique for accelerating the aging of FPGA devices is proposed and demonstrated. The proposed technique uses harmful configurations (short circuits) to accelerate the aging process on targeted portions of an FPGA chip. A testbed is developed for the purpose of measuring FPGA degradation. Using this testbed it is shown that implementing thousands of short circuits in FPGA fabric generates enough heat to cause significant damage to the chip, reducing switching speeds by up to 8%. It is also demonstrated that different parts of the FPGA fabric can be aged at different rates, with some parts …


Pyrolysis Kinetics Of Wildland Vegetation Using Model-Fitting Methods, Ellie Amini, Mohammad-Saeed Safdari, Nathan Johnson Brigham, David R. Weise, Thomas H. Fletcher May 2021

Pyrolysis Kinetics Of Wildland Vegetation Using Model-Fitting Methods, Ellie Amini, Mohammad-Saeed Safdari, Nathan Johnson Brigham, David R. Weise, Thomas H. Fletcher

Faculty Publications

Slow-heating pyrolysis experiments of 14 plant species native to forests in the southern United States were conducted in a TGA to find the kinetic parameters for slow pyrolysis of all live and air-dried plant samples. Kinetic coefficients were determined from the data using model-fitting methods, resulting in single kinetic parameters for the entire pyrolysis process which can be used by wildland fire modelers. The model forms explored here are a simple one-step model and single and multiple reaction distributed activation energy (DAE) models. The mass loss and derivative mass loss data were fitted simultaneously at heating rates of 10, 20, …


Using Blade Element Momentum Methods With Gradient-Based Design Optimization, Andrew Ning May 2021

Using Blade Element Momentum Methods With Gradient-Based Design Optimization, Andrew Ning

Faculty Publications

Blade element momentum methods are widely used for initial aerodynamic analysis of propellers and wind turbines. A wide variety of correction methods exist, but common to all variations, a pair of residuals are converged to ensure compatibility between the two theories. This paper shows how to rearrange the sequence of calculations reducing to a single residual. This yields the significant advantage that convergence can be guaranteed and to machine precision. Both of these considerations are particularly important for gradient- based optimization where a wide variety of atypical inputs may be explored, and where tight convergence is necessary for accurate derivative …


Five Degree-Of-Freedom Property Interpolation Of Arbitrary Grain Boundaries Via Voronoi Fundamental Zone Octonion Framework, Sterling Gregory Baird Apr 2021

Five Degree-Of-Freedom Property Interpolation Of Arbitrary Grain Boundaries Via Voronoi Fundamental Zone Octonion Framework, Sterling Gregory Baird

Theses and Dissertations

In this work we introduce the Voronoi fundamental zone octonion (VFZO) interpolation framework for grain boundary (GB) structure-property models and surrogates. The VFZO framework offers an advantage over other five degree-of-freedom (5DOF) based property interpolation methods because it is constructed as a point set in a Riemannian manifold. This means that directly computed Euclidean distances approximate the original octonion distance with significantly reduced computation runtime (∼7 CPU minutes vs. 153 CPU days for a 50000×50000 pairwise-distance matrix). This increased efficiency facilitates lower interpolation error through the use of significantly more input data. We demonstrate grain boundary energy (GBE) interpolation results …


Digital Signal Processing Algorithms Implemented On Graphics Processing Units And Software Development For Phased Array Receiver Systems, Mark William Ruzindana Apr 2021

Digital Signal Processing Algorithms Implemented On Graphics Processing Units And Software Development For Phased Array Receiver Systems, Mark William Ruzindana

Theses and Dissertations

Phased array receivers are a set of antenna elements that are capable of forming multiple simultaneous beams over a field of view. In radio astronomy, the study of deep space radio sources, a phased array feed (PAF) is placed at the focus of a large dish telescope that spatially samples the focal plane. PAFs provide an increase in the field of view as compared to the traditional single pixel horn feed, thereby increasing survey speed while maintaining low sensitivity. Phased arrays are also capable of radio frequency interference (RFI) mitigation which is useful in both radio astronomy and wireless communications …


Trajectory Generation And Tracking Control For Winged Electric Vertical Takeoff And Landing Aircraft, Jacob B. Willis Apr 2021

Trajectory Generation And Tracking Control For Winged Electric Vertical Takeoff And Landing Aircraft, Jacob B. Willis

Theses and Dissertations

The development of high-energy-density batteries, advanced sensor technologies, and advanced control algorithms for multirotor electric vertical takeoff and landing (eVTOL) unmanned aerial vehicles (UAVs) has led to interest in using these vehicles for a variety of applications including surveillance, package delivery, and even human transportation. In each of these cases, the ideal vehicle is one that can maneuver in congested spaces, but is efficient for traveling long distances. The combination of wings and vectored thrust make winged eVTOLs the obvious choice. However, these aircraft experience a much wider range of flight conditions that makes them challenging to model and control. …


Electrical Capacitance Measurements To Assess European Corn Borer Infestation In Maize, Mavrik D. Thomas Apr 2021

Electrical Capacitance Measurements To Assess European Corn Borer Infestation In Maize, Mavrik D. Thomas

Theses and Dissertations

The European Corn Borer (ECB), Ostrinia nubilalis, is an agricultural pest which bores small holes in the rind of maize stalks and then proceeds to consume the pith. Because most of the damage to the stalk is internal, it is difficult to quantify the damage to an individual stalk without time-consuming, manual examination. This work explored the hypothesis that internal damage could be detected and quantified using non-destructive, electromagnetic measurements. Laboratory experiments and numerical simulation studies predicted changes in capacitance of stalks due to hollow core ECB damage. A guarded probe device to measure electrical impedance from 500 Hz to …


Compiler-Assisted Software Fault Tolerance For Bare Metal And Rtos Applications On Embedded Platforms, Benjamin James Apr 2021

Compiler-Assisted Software Fault Tolerance For Bare Metal And Rtos Applications On Embedded Platforms, Benjamin James

Theses and Dissertations

In the presence of ionizing particles and other high-energy atomic sources, many electronic and computer systems fail. Single event upsets (SEUs) can be mitigated through hardware and/or software methods. Previous research at BYU has introduced COAST, a compiler-based tool that can automatically add software protection schemes to improve fault coverage of programs. This thesis will expand on the work already done with the COAST project by proving its effectiveness across multiple platforms and benchmarks. The ability to automatically add fault protection to arbitrary user programs will be very valuable for many application designers. The results presented herein show that mean …


Gravel Liquefaction Assessment With The Dynamic Penetration Test At Non-Liquefaction Sites In Valdez, Alaska And L'Aquila, Italy, Nicholas James Linton Apr 2021

Gravel Liquefaction Assessment With The Dynamic Penetration Test At Non-Liquefaction Sites In Valdez, Alaska And L'Aquila, Italy, Nicholas James Linton

Theses and Dissertations

The development of a reliable, and cost-effective in-situ method for characterizing the liquefaction potential of gravelly soils is a considerable challenge for engineers and researchers. The ability to accurately characterize the liquefaction potential of gravelly soils is an important consideration at port facilities and dams for example. The Dynamic Penetration Test (DPT) provides a reliable and cost-effective method for evaluating the liquefaction resistance of gravelly soils. Probabilistic liquefaction triggering curves based on DPT field data have been developed from data collected at 47 sites in China. However, using the DPT-based liquefaction curves for locations outside of the Chengdu plain in …


Combined Trajectory, Propulsion And Battery Mass Optimization For Solar-Regenerative High-Altitude Long-Endurance Aircraft, Nathaniel Spencer Gates Apr 2021

Combined Trajectory, Propulsion And Battery Mass Optimization For Solar-Regenerative High-Altitude Long-Endurance Aircraft, Nathaniel Spencer Gates

Theses and Dissertations

This thesis presents the work of two significant projects. In the first project, a suite of benchmark problems for grid energy management are presented which demonstrate several issues characteristic to the dynamic optimization of these systems. These benchmark problems include load following, cogeneration, tri-generation, and energy storage, and each one assumes perfect foresight of the entire time horizon. The Gekko Python package for dynamic optimization is introduced and two different solution methods are discussed and applied to solving these benchmarks. The simultaneous solve mode out-performs the sequential solve mode in each benchmark problem across a wide range of time horizons …


Improvements Of Atmospheric Deposition Sampling Procedures And Further Analysis Of Its Impact On Utah Lake, Seth Michael Barrus Apr 2021

Improvements Of Atmospheric Deposition Sampling Procedures And Further Analysis Of Its Impact On Utah Lake, Seth Michael Barrus

Theses and Dissertations

This study focused on Atmospheric Deposition (AD) loading on Utah Lake. Utah Lake is susceptible to Harmful Algal Blooms (HABs) because of its large surface area to volume ratio, proximity to Great Basin dust sources, and various wind patterns from close mountain ranges that blow AD towards the lake. In this study, we continued the collection and analysis of AD samples that started in 2017 and 2018, while reporting additional 2019 and 2020 data. We constructed a sampler on Utah Lake itself, which allowed us to better estimate how AD loads were distributed over the lake. An interpolation assumption was …