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Articles 31 - 60 of 76
Full-Text Articles in Engineering
Electroplating And Machining Of Silicon Carbide Wafers, Madeline Beth Thompson
Electroplating And Machining Of Silicon Carbide Wafers, Madeline Beth Thompson
Theses and Dissertations
Silicon carbide has many properties that make it a promising and desirable material for diverse applications. One such application for silicon carbide wafers is as a transparent cryogenic probe card. This thesis briefly describes the design of a probe card based on a silicon carbide wafer substrate. It includes a description of electroplating fundamentals and demonstrates the feasibility of electroplating copper onto a wafer for the formation of bond pads between the substrate and external PCB ring. The process for electroplating copper with good adhesion and quality based on metal alloy formation, current control, and materials selection is outlined. Results …
Continuous-Time Trajectory Estimation And Its Application To Sensor Calibration And Differentially Flat Systems, Jacob C. Johnson
Continuous-Time Trajectory Estimation And Its Application To Sensor Calibration And Differentially Flat Systems, Jacob C. Johnson
Theses and Dissertations
State estimation is an essential part of any robotic autonomy solution. Continuous-time trajectory estimation is an attractive method because continuous trajectories can be queried at any time, allowing for fusion of multiple asynchronous, high-frequency measurement sources. This dissertation investigates various continuous-time estimation algorithms and their application to a handful of mobile robot autonomy and sensor calibration problems. In particular, we begin by analyzing and comparing two prominent continuous-time trajectory representations from the literature: Gaussian processes and splines, both on vector spaces and Lie groups. Our comparisons show that the two methods give comparable results so long as the same measurements …
A Polarizable Molecular Dynamics Potential For Molten Salt Property Prediction, Jared Thurgood
A Polarizable Molecular Dynamics Potential For Molten Salt Property Prediction, Jared Thurgood
Theses and Dissertations
The present study attempts to find an alternate computational tool to model the complex physical interactions within the molten salt FLiNaK in a way that is both efficient and accurate. Additionally, this study seeks to describe the effects of several different types of impurities on the FLiNaK salt system. This study selects two different polarizable force fields, the AMOEBA polarizable approach and the polarizable ion model, to determine the density and the structure of the impure FLiNaK salt mixtures at typical operating temperatures in molten salt reactors (between 500-900 °C). This study conducts ab initio molecular dynamics (AIMD) simulations and …
Real-Time Spatial Interference Removal And Maximum Ratio Combining In Communication Systems, Adam Gary Whipple
Real-Time Spatial Interference Removal And Maximum Ratio Combining In Communication Systems, Adam Gary Whipple
Theses and Dissertations
Radio frequency interference (RFI) is undesired and commonplace. Using a subspace projection method to spatially remove the interference from a phased array system gives results of a 30 dB interference null rejection (INR). Unmanned systems have been developed to observe underwater activity and communicate their observations to passing aircraft. These systems are currently limited by their use of a single transmitter. The uplink can be improved by using a dual-antenna beam steering approach to maximize the signal-to-noise ratio (SNR) the aircraft receives. This approach demonstrates an increase in SNR of 3 dB when compared to a single transmitter.
Numerical Evaluation Of Forces Affecting Particle Motion In Time-Invariant Pressurized Jet Flow, Donald E. Peterson
Numerical Evaluation Of Forces Affecting Particle Motion In Time-Invariant Pressurized Jet Flow, Donald E. Peterson
Theses and Dissertations
This work evaluates the relative significance of forces determining the motion of a pulverized coal particle under conditions representative of a pressurized oxy-coal combustor. The gravity force and surface forces of drag, fluid stress, added mass, and Basset history are discussed and appropriate forms of these force equations are chosen, with a consideration of spherical and non-spherical drag and the Basset history kernel. Studies from the literature that emphasize specific forces are used to validate the implementation of the force equations and correlations. Modeling is based on time-averaged, one-dimensional motion of a single non-reacting particle along the centerline of a …
Lumbar Skin Strain Fields In The Context Of Skin Adhered Wearables, Andrew Kent Gibbons
Lumbar Skin Strain Fields In The Context Of Skin Adhered Wearables, Andrew Kent Gibbons
Theses and Dissertations
A comprehensive background is herein presented for lumbar skin strain and its effect on skin adhered wearable (SAW) products. A background of the development of computational models of the interaction of skin and novel SAWs being researched is also presented. These include products involving the use of high deflection strain gauges to measure skin strain during functional movements (FMs) as a method to address the complicated phenotyping of the etiological causes of low back pain (LBP). The background concludes with the mathematical calculation of the principal skin strain magnitudes and orientations using retroreflective marker coordinate data in a motion capture …
3rd Party Ip Encryption From Netlist To Bitstream For Xilinx 7-Series Fpgas, Daniel Hutchings
3rd Party Ip Encryption From Netlist To Bitstream For Xilinx 7-Series Fpgas, Daniel Hutchings
Theses and Dissertations
IP vendors need to keep the internal designs of their IP secret from the IP user for security or commercial reasons. The CAD tools provided by FPGA vendors have some built-in functionality to encrypt the IP. However, the IP is consequently decrypted by the CAD tools in order to run the IP through the design flow. An IP user can use APIs provided by the CAD tools to recreate the IP in an unencrypted state. An IP user could also easily learn the internals of a protected IP with the advent of new open-source bitstream to netlist tools. The user …
Investigating Bismuth As A Surrogate For Plutonium Electrorefining, Greg Chipman
Investigating Bismuth As A Surrogate For Plutonium Electrorefining, Greg Chipman
Theses and Dissertations
Conducting research experiments on plutonium electrorefining is difficult due to the significant hazards and regulations associated with nuclear materials. Finding a surrogate for plutonium electrorefining studies would enable more fundamental research to be conducted. Potential surrogates were identified by determining the physical properties required to conduct electrorefining using a molten metal and molten salt in CaCl2 at 1123 K. More potential surrogates were identified by changing the matrix salt to be a LiCl-KCl-CaCl2 eutectic salt with electrorefining conducted at 673-773 K. Ce-CeCl3, In-InCl3, Zn-ZnCl2, Sn-SnCl2, and Bi-BiCl¬3 were investigated as potential plutonium electrorefining surrogates. Ce electrorefining in molten CaCl2 resulted …
Comparison Of Compact Very High Frequency (Vhf) Antennas For Small Airborne Ground Penetrating Radar, Tayler Austen Livingston
Comparison Of Compact Very High Frequency (Vhf) Antennas For Small Airborne Ground Penetrating Radar, Tayler Austen Livingston
Theses and Dissertations
UHF bands because more penetration can be achieved at low frequencies. Consequently, large antennas are required, which limits their use for small airborne applications. This thesis explores various GPR antenna designs for a bi-static system that are at least operational from 225 MHz to 255 MHz and suitable for small airborne applications. The 3D electromagnetic simulation software Ansys high-frequency structure simulator (HFSS) was used to simulate various sizes of strip dipole, triangular bowtie, half elliptical bowtie, and elliptical bowtie antennas. Several physical models were constructed to validate the return loss simulation results. Additionally, simulation data is included for a wire …
Heat Transfer To Rolling Or Sliding Drops On Inclined Heated Superhydrophobic Surfaces, Joseph Merkley Furner
Heat Transfer To Rolling Or Sliding Drops On Inclined Heated Superhydrophobic Surfaces, Joseph Merkley Furner
Theses and Dissertations
This thesis examines the time resolved heat transfer to drops rolling or sliding along inclined, subcritical heated non-wetting surfaces. Results were experimentally obtained using IR imaging for a smooth hydrophobic surface and post as well as rib structured superhydrophobic surfaces of varying solid fraction (f_s = 0.06 - 0.5). Tests were performed at varying inclination angle (α = 10, 15, 20, and 25°), drop volume (12, 20, 30, and 40 μL), and surface temperature (T_w = 50, 65, and 80 °C). Rib structured superhydrophobic surfaces were explored for drops moving parallel and perpendicular to the rib structures. The findings indicate …
Radar Processing Techniques For Using The Limesdr Mini As A Short-Range Lfm Radar, Jacob Scott Stratford
Radar Processing Techniques For Using The Limesdr Mini As A Short-Range Lfm Radar, Jacob Scott Stratford
Theses and Dissertations
Drone-mounted ground penetrating radar (GPR) has the capability to investigate terrain that is inaccessible or hazardous to humans. A linear frequency-modulated (LFM) radar with the potential for GPR applications is described based on the LimeSDR Mini software defined radio (SDR). Challenges of the LimeSDR Mini radar include the SDR's lack of support for transmitter-receiver synchronization and high bleedthrough leakage. These issues are overcome through corrective software processing techniques including deconvolution of the SDR's system impulse response and digital feed-through nulling. Feed-through nulling is effective at reducing bleedthrough leakage, achieving a 26 dB reduction in power. Although high noise can confound …
Microfabrication Of Silicon Carbide And Metallized Polymers Using A Femtosecond Laser, Joseph Taylor Eddy
Microfabrication Of Silicon Carbide And Metallized Polymers Using A Femtosecond Laser, Joseph Taylor Eddy
Theses and Dissertations
Femtosecond lasers deliver a high peak concentration of optical power while maintaining low average power. With an accompanying optical setup, this power can be focused and used for high-precision fabrication of metallized polymers via ablation, creating conductive structures on a thin film. These lasers can also be harnessed in tandem with hydrofluoric acid and the two-photon absorption principle to selectively etch silicon carbide, a very durable and machining-resistant semiconductor with desirable properties. This thesis presents improvements made to the Laser-Assisted Chemical Etching (LACE) technique and the ablation system. ��, the two- photon absorption coefficient of silicon carbide, is measured and …
Detecting Lumbar Muscle Fatigue Using Nanocomposite Strain Gauges, Darci Ann Billmire
Detecting Lumbar Muscle Fatigue Using Nanocomposite Strain Gauges, Darci Ann Billmire
Theses and Dissertations
Introduction: Muscle fatigue can contribute to acute flare-ups of lower back pain with associated consequences such as pain, disability, lost work time, increased healthcare utilization, and increased opioid use and potential abuse. The SPINE Sense system is a wearable device with 16 high deflection nanocomposite strain gauge sensors on kinesiology tape which is adhered to the skin of the lower back. This device is used to correlate lumbar skin strains with the motion of the lumbar vertebrae and to phenotype lumbar spine motion. In this work it was hypothesized that the SPINE Sense device can be used to detect differences …
Friction And Heat Transfer Modeling Of The Tool And Workpiece Interface In Friction Stir Welding Of Aa 6061-T6 For Improved Simulation Accuracy, Ryan Melander
Theses and Dissertations
Friction stir welding (FSW) is a solid-state joining process that offers advantages over traditional fusion welding. The amount of heat generated during a FSW process greatly influences the final properties of the weld. The heat is generated through two main mechanisms: friction and plastic deformation, with friction being the larger contributor in a FSW process. There is a need to develop better predictive models of the heat generation and heat transfer in FSW. Almost all models seen in the literature validate temperature predictions on only one side of the tool/workpiece interface, thus ignoring possible inaccuracy that comes from incorrect partitioning …
Securing Wireless Communication Via Information-Theoretic Approaches: Innovative Schemes And Code Design Techniques, Morteza Shoushtari
Securing Wireless Communication Via Information-Theoretic Approaches: Innovative Schemes And Code Design Techniques, Morteza Shoushtari
Theses and Dissertations
Historically, wireless communication security solutions have heavily relied on computational methods, such as cryptographic algorithms implemented in the upper layers of the network stack. Although these methods have been effective, they may not always be sufficient to address all security threats. An alternative approach for achieving secure communication is the physical layer security approach, which utilizes the physical properties of the communication channel through appropriate coding and signal processing. The goal of this Ph.D. dissertation is to leverage the foundations of information-theoretic security to develop innovative and secure schemes, as well as code design techniques, that can enhance security and …
Evaluating Parameter Uncertainty In Transportation Demand Models, Natalie Mae Gray
Evaluating Parameter Uncertainty In Transportation Demand Models, Natalie Mae Gray
Theses and Dissertations
The inherent uncertainty in travel forecasting models -- arising from errors in input data, parameter estimation, or model formulation -- is receiving increasing attention from the scholarly and practicing community. In this research, we investigate the variance in forecasted traffic volumes resulting from varying the mode and destination choice parameters in an advanced trip-based travel demand model. Using Latin hypercube sampling to construct several hundred combinations of parameters across the plausible parameter space, we introduce substantial changes to mode and destination choice logsums and probabilities. However, the aggregate effects of of these changes on forecasted traffic volumes is small, with …
Evaluating Effects Of Urban Growth Within The Greater Salt Lake Area On Local Meteorological Conditions Using Urban Canopy Modeling, Corey L. Smithson
Evaluating Effects Of Urban Growth Within The Greater Salt Lake Area On Local Meteorological Conditions Using Urban Canopy Modeling, Corey L. Smithson
Theses and Dissertations
The increasing urbanization of the greater Salt Lake City area (GSLA) has contributed to the development of an urban canopy over this area. This canopy refers to the effects of building profiles, varying land surface properties and anthropogenic heating on local meteorological conditions including temperature, humidity, and wind velocity. Urban Canopy Models (UCMs) can be used to represent these characteristics on a mesoscale without needing to develop models accounting for effects of individual buildings. One method used to classify urban areas are Local Climate Zones (LCZs), which assign different properties to different types of urban areas. A baseline model that …
Predictive Modeling The Impact Of Engineered Products In Dynamic Sociotechnical Systems: An Agent-Based Approach, Christopher S. Mabey
Predictive Modeling The Impact Of Engineered Products In Dynamic Sociotechnical Systems: An Agent-Based Approach, Christopher S. Mabey
Theses and Dissertations
The impact of engineered products is a topic of increasing concern in society. The impact of a product can fall into the categories of economic, environmental, or social impact; the last category is defined as the effect of a product on the daily lives of people. Design teams lack sufficient tools to help improve the impact of products and understand the impact of products at scale in society. This dissertation aims to provide insight and methods for improving the social, environmental, and economic impact of engineered products. The majority of the research focuses on the prediction of product impacts on …
Design Of A Transparent Cryogenic Silicon Carbide Probe Card With Tungsten Probe Tips, Ryan Beazer
Design Of A Transparent Cryogenic Silicon Carbide Probe Card With Tungsten Probe Tips, Ryan Beazer
Theses and Dissertations
DoD EO/IR applications continue to push imaging technology. Next generation advances require new material systems, novel device structures, as well as the improvement and development of read out integrated circuits. The common methodology used to assess devices and materials is to process test chip structures and focal plane arrays. Test chips have advantages over focal plane arrays; such as, variable area and stand alone devices and can be measured as a function of bias and temperature; however, focal plane arrays are the heart of the imager, but are measured through the read out integrated circuits, which can add complexity to …
Methods For Designing Compact And Deployable Origami-Inspired Flat-Foldable Spacecraft Antennas And Other Systems, Collin Ryan Ynchausti
Methods For Designing Compact And Deployable Origami-Inspired Flat-Foldable Spacecraft Antennas And Other Systems, Collin Ryan Ynchausti
Theses and Dissertations
There are times when it is desirable for devices to be stowed compactly, ``transported'' to the location of their desired use, and then deployed to another stable shape or configuration to perform their designed function. Origami-based mechanisms are beneficial in these cases due to their compact, folded nature and large deployments. Unlike traditional mechanical design, compliant mechanism and origami-based design approaches inherently have coupled characteristics, creating complex design problems. The research presented here discusses metrics, methods, and designs to aid in the design of origami-adapted and compliant mechanisms, focusing on the design case of deployable space systems. First, the hexagonal …
Morphogenetic Engineering Of Synthetic Protocell Systems, Qinyu Zhu
Morphogenetic Engineering Of Synthetic Protocell Systems, Qinyu Zhu
Theses and Dissertations
Observing and studying how life forms behave, i.e., their movement, adaptability, and so on, have enabled human beings to develop new technologies or optimize existing ones. One of the more noticeable phenomena in Nature is morphogenesis. Morphogenetic processes exist in different stages of biological development, from cellular division to tissue and organ formation. It is easy to observe shape development during mophogenesis due to emerging imaging techniques. However, it is hard to understand this process due to its complex organization, and the morphogenetic responses can be induced by a variety of chemicals or mechanical stresses and are subject to the …
Thermal Atomization Of Impinging Drops On Superheated Superhydrophobic Surfaces, Eric Lee
Thermal Atomization Of Impinging Drops On Superheated Superhydrophobic Surfaces, Eric Lee
Theses and Dissertations
Drop impact on a surface has an effect on nearly every industry and this impact may have adverse effects if not controlled. Superhydrophobic (SH) surfaces have been created with the extreme ability to repel water. These surfaces exist in nature but may also be fabricated using modern techniques. This thesis explores heat transfer from these SH surfaces to drops impacting them. This thesis is devoted to increasing the breadth of knowledge of thermal atomization during drop impingement on superheated SH surfaces. When a water drop impinges vertically on a horizontal superheated surface, intense atomization can occur. The atomization is caused …
Soft Robot Configuration Estimation: Towards Load-Agnostic Soft-Bodied Proprioception, Christian Peter Sorensen
Soft Robot Configuration Estimation: Towards Load-Agnostic Soft-Bodied Proprioception, Christian Peter Sorensen
Theses and Dissertations
The objective of the work described in this thesis is the development of a configuration estimation scheme for quasi soft-bodied robots, with the end goal being accurate soft-robot proprioception to enable robotic manipulation of unknown external loads. The first chapter introduces the problem and state-of-the-art modeling methods. The second chapter presents work we did building on previous research on a novel sensing scheme for soft-bodied robotic configuration estimation. The third chapter discusses the development of a geometric shape-sensing model based on overlapping tendon-length measurements. This model is geometrically exact for a body composed of two constant curvature segments in bending. …
A Statistical Approach For Analyzing Expectations Alignment Between Design Teams And Their Project Stakeholders, Matthew Christian Goodson
A Statistical Approach For Analyzing Expectations Alignment Between Design Teams And Their Project Stakeholders, Matthew Christian Goodson
Theses and Dissertations
Successful project management requires continuous communication aligning the expectations between project stakeholders and the project team. Expectations include both product expectations (how the product will look, feel, and perform) and programmatic expectations (timelines, deliverables, expenditure of project resources). In order to make the most effective use of project resources throughout the life of the project, a process or tool for quickly aligning expectations as closely as possible should be employed early on in the project. Project management literature is lacking in tools for aligning expectations, and solutions and best practices need to be determined since the current best option is …
Gradient-Based Optimization Of Highly Flexible Aeroelastic Structures, Taylor G. Mcdonnell
Gradient-Based Optimization Of Highly Flexible Aeroelastic Structures, Taylor G. Mcdonnell
Theses and Dissertations
Design optimization is a method that can be used to automate the design process to obtain better results. When applied to aeroelastic structures, design optimization often leads to the creation of highly flexible aeroelastic structures. There are, however, a number of conventional design procedures that must be modified when dealing with highly flexible aeroelastic structures. First, the deformed geometry must be the baseline for weight, structural, and stability analyses. Second, potential couplings between aeroelasticity and rigid-body dynamics must be considered. Third, dynamic analyses must be modified to handle large nonlinear displacements. These modifications to the conventional design process significantly increase …
Experimental Validation Of A Vibration-Based Sound Power Method, Trent P. Bates
Experimental Validation Of A Vibration-Based Sound Power Method, Trent P. Bates
Theses and Dissertations
A vibration-based sound power (VBSP) measurement method is appealing because of its potential versatility in application compared to pressure- and intensity-based methods. The VBSP method is based on the well-known elementary radiators approach and is reliant on the acoustic radiation resistance matrix. Previous research has developed and validated the VBSP method for flat plates and cylinders. This thesis details work on extending the VBSP method to arbitrarily-curved structures. The approach of computing surface normal velocities from 3D velocity data measured by a scanning laser Doppler vibrometer (SLDV) is presented. This approach is validated with experimental sound power results of a …
Perfusion Pressure-Flow Relationships In Synthetic Poroelastic Vocal Fold Models, Cooper B. Thacker
Perfusion Pressure-Flow Relationships In Synthetic Poroelastic Vocal Fold Models, Cooper B. Thacker
Theses and Dissertations
The purpose of this research was to study perfusion pressure-flow relationships in self-oscillating synthetic poroelastic vocal fold (VF) models before, during, and after vibration. This was accomplished by developing a custom ultra-soft poroelastic material, incorporating the poroelastic material as the cover layer in a synthetic VF model, and studying the model vibratory response and the flow rate of fluid perfused through the cover layer while undergoing flow-induced vibration. The custom ultra-soft poroelastic material was developed using the method of direct templating with sucrose spheres as the sacrificial template and silicone as the infiltration medium. The average modulus of elasticity of …
Factors That Influence The Recruitment And Retention Of Civil Engineers, Gina Young Souriac
Factors That Influence The Recruitment And Retention Of Civil Engineers, Gina Young Souriac
Theses and Dissertations
With a growing demand for civil engineers in the United States, understanding factors that influence students to choose civil engineering (CE) as a major in college, pursue an M.S. degree in CE, and persist in the CE industry can lead to valuable insights for recruitment and retention of future and current civil engineers. Additionally, understanding factors that prominently influence male and female civil engineers to persist in and depart from CE, separately, can lead to valuable insight towards improving focused recruitment and retention of both genders. This thesis includes three research studies that identify, analyze, and discuss these important factors. …
Testing Methodologies And Results Of Radiation Induced Soft Errors For A Cots Sram, Fram, And Soc, Wesley Raymond Stirk
Testing Methodologies And Results Of Radiation Induced Soft Errors For A Cots Sram, Fram, And Soc, Wesley Raymond Stirk
Theses and Dissertations
Methods for testing commercial off-the-shelf (COTS) digital devices at varying levels of complexity is presented and discussed as well as the results for testing a COTS SRAM, FRAM, and SoC using these methodologies in a pulsed dose rate environment at Little Mountain Test Facility (LMTF) and neutron testing at Los Alamos Neutron Science Center (LANSCE). Investigations at LMTF revealed a dependence in all three devices on the integrated dose of a single pulse of radiation, implying that the duration of radiation plays a significant role in the response. The test infrastructure necessary to dynamically access an FRAM at LMTF and …
Exploring The Impact Of Hour Of Code On Students' Cs Interest And Perceptions, Jessica Marie Yauney
Exploring The Impact Of Hour Of Code On Students' Cs Interest And Perceptions, Jessica Marie Yauney
Theses and Dissertations
As the focus on computer science in K-12 classrooms grows, the 'Hour of Code' program has also grown. As Hour of Code is one of the largest educational campaigns, it is worth evaluation to ensure effects are well understood so that implementation can be made most effective. This research sought to better understand the impact of Hour of Code. This thesis presents findings from a systematic review and from a quasi-experimental study. A large number of research articles have been published on Hour of Code. Systematic review identified 64 papers including reports from experiments testing the efficacy of Hour of …