Engineering Commons^™

Perturbed Stress Field Of The Human Lens Capsule After Cataract Surgery, Kurt Ameku, Caleb Berggren, Ryan M. Pedrigi

UCARE: Research Products

Current modeling of the human lens capsule has been focused on the mechanism of accommodation and its decline with age, but few studies have modeled the effects of cataract surgery and quantified the altered mechanical environment introduced by the procedure. The goal of this study is to develop the first fully 3-D finite element model of the post-surgical human lens capsule with an implanted device in order to characterize lens capsule mechanics after cataract surgery. The model demonstrates a highly perturbed stress field compared to the native state, which we hypothesize is the primary driving force behind the long-term errant …

Nanoparticle Treatment To Counter Reactive Oxygen Species After Traumatic Brain Injury, Brandon Mcdonald, Forrest Kievit

UCARE: Research Products

Traumatic brain injury (TBI) is defined as damage to the brain, resulting from an external mechanical force, such as an impact to the head (Kievit et. al, 2016).There are several examples that could result in a potential TBI; such as falling with contact to the head, car accidents and even physical activities including football, wrestling, and boxing. Because of the several different scenarios that an individual could impact their head, TBI’s have become an all too common aspect of everyday life. TBI is currently the leading cause of death and disability in children and adults under the age of 45, …

Trajectory Simulation With Battery Modeling For Electric Powered Unmanned Aerial Vehicles, Ege Konuk

Mechanical & Aerospace Engineering Theses & Dissertations

Fixed wing electric powered unmanned aerial vehicles (UAVs) has been widely adopted for the last decade in a great number of applications. One of the primary advantages to fixed wing versus multi-rotor designs is the efficiency in forward flight with best possible range and endurance capabilities. In electrically powered air vehicles range and endurance are monitored by the State-of-Charge (SOC) of the battery. To understand the capabilities of the battery, discharge experiments can be conducted in lab environments; however, sometimes the results are difficult to integrate in flight simulations.

In this thesis, a trajectory simulation is developed that can estimate …

Lateral-Torsional Instability And Biaxial Flexure Of Continuous Gfrp Beams Including Warping And Shear Deformations, Waverly G. Hampton

Civil & Environmental Engineering Theses & Dissertations

This dissertation presents an experimental and theoretical study of the lateral-torsional instability and biaxial flexure of Glass Fiber Reinforced Polymer (GFRP) beams including warping and shear deformation effects. The theoretical analysis is based on three simultaneous differential equations of equilibrium with new terms added to account for shear deformation effects. To solve these equations, algorithms based upon a central finite-difference approach are then developed. The experimental study is conducted on a series of single- and multi-span beams subjected to concentrated loads. The predicted beam behavior agreed well with that observed experimentally. The investigation revealed that the ASCE-LRFD Prestandard for pultruded …

Thermal Contact Resistance Measurement And Related Uncertainties, Amanda Elizabeth Stark

Mechanical & Aerospace Engineering Theses & Dissertations

Thermal contact resistance is an important parameter in detailed thermal analysis and design of aerospace systems. The ability to determine thermal contact resistance reliably can have a significant impact on the fidelity of thermal models—particularly for space applications. The 2004 NASA Langley Research Center thermal contact resistance test apparatus has been employed to evaluate two methods for inferring estimated interface surface temperatures so that thermal contact resistance can be calculated more accurately. The traditional method of extrapolation is a steady-state approach, while the new method utilizes inverse heat transfer techniques to account for inherent unsteadiness in these quasi-steady-state measurements. The …

Deposition And Characterization Of Indium Nitride And Aluminum Nitride Thin Films By Reactive Sputtering, Sushma Swaraj Atluri

Electrical & Computer Engineering Theses & Dissertations

Intensive research has been carried out on III-V semiconductors for over a century due to their various applications in the field of Microelectronics, Optics, and Photonics. Among III-V materials, the III-nitrides, for example Aluminum Nitride, Indium Nitride, Gallium Nitride and their ternary alloys are known for their unique properties. All the III-Nitride Compounds are direct bandgap semiconductors with a bandgap ranging from 0.7 eV to 6.2 eV covering the entire visible region and extending to the UV region as well. Despite having many applications, fabricating good quality thin films without defects is quite a challenge. They are typically grown using …

A Rule Based Control Algorithm For On-Ramp Merge With Connected And Automated Vehicles, Ehsan Beheshtitabar

Civil & Environmental Engineering Theses & Dissertations

One of the designs for future highways with the flow of Connected Automated Vehicles (CAVs) cars will be a dedicated lane for the CAVs to form platoons and travel with higher speeds and lower headways. The connectivity will enable the formation of platoons of CAVs traveling beside non-platoon lanes. The advent of connectivity between vehicles and the infrastructure will enable advanced control strategies ̶ improving the performance of the traffic ̶ to be incorporated in the traffic system. The merge area in a multilane highway with CAVs is one of the sections which can be enhanced by the operation of …

Lignin: A Likely Precursor Of A Significant Fraction Of Humic Substances Via Oxidative Transformations, Seyyedhadi Khatami

Chemistry & Biochemistry Theses & Dissertations

Lignin is a major component of decaying terrestrial vegetation in soils and has been arguably reported to contribute substantially to the formation of soil carbon humus, and natural dissolved organic matter (DOM). To better understand the process by which this humification occurs, lignin and lignin-derived monomers were subjected to both biotic and abiotic oxidation processes. Two well-known oxidative transformation strategies were employed. The first involved the fungal degradation of brown-rot degraded wood subjected to a white-rot fungus (Phanerochaete chrysosporium) whose enzymes are particularly effective in lignin degradation via enzymatic oxidation. This enzymatic attack was monitored by ultrahigh resolution …

An Argument Against Satellite Resiliency: Simplicity In The Face Of Modern Satellite Design, Dax Linville, Robert A. Bettinger

Faculty Publications

The US Air Force and the wider US government rely heavily on space-based capabilities in various orbital regimes to project national security and sovereignty. However, these capabilities are enabled by the design, launch, and operation of satellites produced with a design methodology that favors large, monolithic, and technologically exquisite space systems. Despite the ability for these satellites to provide enduring and resilient capabilities, they suffer from a woefully long acquisition process that debilitates any prospect of rapid satellite reconstitution in the event of a space war.

Analysis Of Military Construction Cost Growth In Usaf Major Defense Acquisition Programs, Emily E. Angell, Edward D. White, Jonathan D. Ritschel, Alfred E. Thal Jr.

Faculty Publications

This study uses descriptive and inferential statistics to identify cost growth Analysis of Military Construction of military construction (MILCON) at the programmatic level, while bridging the gap between Selected Acquisition Report (SAR) estimates and actual project costs. Findings of this study aid the cost community with appropriate allocation of resources in developing these estimates. Overall, Major Defense Acquisition Programs (MDAP) appear to experience more negative growth (cost savings) in MILCON estimates on reviewed SARs— typically less than 0.2% of the total program cost. SAR estimates became more accurate from the first to last SAR in comparison to the total MILCON …

Investigating The Feasibility And Stability For Modeling Acoustic Wave Scattering Using A Time-Domain Boundary Integral Equation With Impedance Boundary Condition, Michelle E. Rodio

Mathematics & Statistics Theses & Dissertations

Reducing aircraft noise is a major objective in the field of computational aeroacoustics. When designing next generation quiet and environmentally friendly aircraft, it is important to be able to accurately and efficiently predict the acoustic scattering by an aircraft body from a given noise source. Acoustic liners are an effective tool for aircraft noise reduction and are characterized by a frequency-dependent impedance. Converted into the time-domain using Fourier transforms, an impedance boundary condition can be used to simulate the acoustic wave scattering by geometric bodies treated with acoustic liners

This work considers using either an impedance or an admittance (inverse …

Experimental Determination Of The (0/−) Level For Mg Acceptors In Β-Ga2O3 Crystals, Christopher A. Lenyk, Timothy D. Gustafson, Sergey A. Basun, Larry E. Halliburton, Nancy C. Giles

Faculty Publications

Electron paramagnetic resonance (EPR) is used to experimentally determine the (0/−) level of the Mg acceptor in an Mg-doped β-Ga₂O₃ crystal. Our results place this level 0.65 eV (±0.05 eV) above the valence band, a position closer to the valence band than the predictions of several recent computational studies. The crystal used in this investigation was grown by the Czochralski method and contains large concentrations of Mg acceptors and Ir donors, as well as a small concentration of Fe ions and an even smaller concentration of Cr ions. Below room temperature, illumination with 325 nm laser light …

Applying Control Abstraction To The Design Of Human–Agent Teams, Clifford D. Johnson, Michael E. Miller, Christina F. Rusnock, David R. Jacques

Faculty Publications

Levels of Automation (LOA) provide a method for describing authority granted to automated system elements to make individual decisions. However, these levels are technology-centric and provide little insight into overall system operation. The current research discusses an alternate classification scheme, referred to as the Level of Human Control Abstraction (LHCA). LHCA is an operator-centric framework that classifies a system’s state based on the required operator inputs. The framework consists of five levels, each requiring less granularity of human control: Direct, Augmented, Parametric, Goal-Oriented, and Mission-Capable. An analysis was conducted of several existing systems. This analysis illustrates the presence of each …

Single-Pulse, Kerr-Effect Mueller Matrix Lidar Polarimeter, Keyser, Christian K., Richard K. Martin, Helena Lopez-Aviles, Khanh Nguyen, Arielle M. Adams, Demetrios Christodoulides

Faculty Publications

We present a novel light detection and ranging (LiDAR) polarimeter that enables measurement of 12 of 16 sample Mueller matrix elements in a single, 10 ns pulse. The new polarization state generator (PSG) leverages Kerr phase modulation in a birefringent optical fiber, creating a probe pulse characterized by temporally varying polarization. Theoretical expressions for the Polarization State Generator (PSG) Stokes vector are derived for birefringent walk-off and no walk-off and incorporated into a time-dependent polarimeter signal model employing multiple polarization state analyzers (PSA). Polarimeter modeling compares the Kerr effect and electro-optic phase modulator–based PSG using a single Polarization State Analyzer …

Alaska Part 135 Operations: The Need For Additional Regulatory Oversight And Continuous Aircraft Tracking, April A. Larsen

Student Works

With a focus on Alaska, this research illustrates the lack of regulatory oversight pertaining to Title 14 CFR Part 135 operators, including SMS, training, and equipment requirements. As of January 2020, under the Federal Aviation Administration’s NextGen initiative, all aircraft flying in controlled airspace are required to have an Automatic Dependent Surveillance – Broadcast (ADS– B) system installed and operational. Many Alaskan operators fly in hazardous terrain, and marginal weather, with little to no communication, yet ADS-B is not a requirement as they are in uncontrolled airspace. Alaska also lacks vital aviation infrastructure including adequate instrument approach procedures, weather monitoring …

Virtual Satcom, Long Range Broadband Digital Communications, Dennis George Watson

Electrical & Computer Engineering Theses & Dissertations

The current naval strategy is based on a distributed force, networked together with high-speed communications that enable operations as an intelligent, fast maneuvering force. Satellites, the existing network connector, are weak and vulnerable to attack. HF is an alternative, but it does not have the information throughput to meet the distributed warfighting need. The US Navy does not have a solution to reduce dependency on space-based communication systems while providing the warfighter with the required information speed.

Virtual SATCOM is a solution that can match satellite communications (SATCOM) data speed without the vulnerable satellite. It is wireless communication on a …

Biphasic Gene Electrotransfer Enhances Gene Delivery In Vitro, John Bui

Biomedical Engineering Theses & Dissertations

The application of short, pulsed electric fields to eukaryotic cells and tissues has been shown to permeabilize cells. This phenomenon has been used for clinical applications for irreversible electroporation of cancer cells or for molecule delivery for drug or gene therapies. Typically, a monophasic (monopolar) pulse train is used; however, recent studies have explored the possibility of using biphasic (often referred to as bipolar) pulses, primarily for irreversible electroporation (IRE), which report reduced muscle contraction during pulse train application compared to monophasic pulses. Additional studies show improved transfection efficiency using biphasic pulses, conversely, with low cell viability. The purpose of …

Longitudinal Brain Tumor Tracking, Tumor Grading, And Patient Survival Prediction Using Mri, Linmin Pei

Electrical & Computer Engineering Theses & Dissertations

This work aims to develop novel methods for brain tumor classification, longitudinal brain tumor tracking, and patient survival prediction. Consequently, this dissertation proposes three tasks. First, we develop a framework for brain tumor segmentation prediction in longitudinal multimodal magnetic resonance imaging (mMRI) scans, comprising two methods: feature fusion and joint label fusion (JLF). The first method fuses stochastic multi-resolution texture features with tumor cell density features, in order to obtain tumor segmentation predictions in follow-up scans from a baseline pre-operative timepoint. The second method utilizes JLF to combine segmentation labels obtained from (i) the stochastic texture feature-based and Random Forest …

Deep Cellular Recurrent Neural Architecture For Efficient Multidimensional Time-Series Data Processing, Lasitha S. Vidyaratne

Electrical & Computer Engineering Theses & Dissertations

Efficient processing of time series data is a fundamental yet challenging problem in pattern recognition. Though recent developments in machine learning and deep learning have enabled remarkable improvements in processing large scale datasets in many application domains, most are designed and regulated to handle inputs that are static in time. Many real-world data, such as in biomedical, surveillance and security, financial, manufacturing and engineering applications, are rarely static in time, and demand models able to recognize patterns in both space and time. Current machine learning (ML) and deep learning (DL) models adapted for time series processing tend to grow in …

Dod Mission Engineering And Integration Explorative-Exploitative Architecture For Technology Innovation, Jose L. Bricio-Neto

Engineering Management & Systems Engineering Theses & Dissertations

The ability of U.S. Department of Defense to achieve timely innovation in support of U.S. National Defense and Military Strategies continues to increase in significance. The growing challenges in U.S. Department of Defense (DoD) technological innovation in a context of global security and rapid pace of global competitiveness continue to reveal many shortcomings in current weapon systems development and acquisition practice. As the pace of technological innovation is accelerating, the DoD faces the challenge that the same disruptive technological advances are also being made available to or developed by its adversaries. Based on literature review, no innovation system theory exists …

Highly Transmissive Scalable Colored Coatings For Architectural Photovoltaic Panels, Akbar Ali Syed

Electrical & Computer Engineering Theses & Dissertations

Highly transmissive coatings were developed by fabricating thin films using SiO₂ and SiO₂/TiO₂ core/shell nanoparticles on glass substrates and on the photovoltaic cell glass covers. This coating is to maintain an attractive color appearance of the exterior surface for architecturally integrated photovoltaics and can be coated on fabricated photovoltaic panels. The color and optical properties of the nanoparticle coating was investigated for different nanoparticle diameters of 200-400 nm for SiO₂ nanoparticles and core/shell nanoparticles having SiO₂/TiO₂ structure with 300 ± 11 nm diameter, and SiO₂/TiO₂/SiO₂ structure with …

Effects Of Transparency And Haze On Trust And Performance During A Full Motion Video Analysis Task, Sarah C. Leibner

Psychology Theses & Dissertations

Automation is pervasive across all task domains, but its adoption poses unique challenges within the intelligence, surveillance, and reconnaissance (ISR) domain. When users are unable to establish optimal levels of trust in the automation, task accuracy, speed, and automation usage suffer (Chung & Wark, 2016). Degraded visual environments (DVEs) are a particular problem in ISR; however, their specific effects on trust and task performance are still open to investigation (Narayanaswami, Gandhe, & Mehra, 2010). Research suggests that transparency of automation is necessary for users to accurately calibrate trust levels (Lyons et al., 2017). Chen et al. (2014) proposed three levels …

Through-Thickness Reinforcement And Repair Of Carbon Fiber Based Honeycomb Structures Under Flexure And Tension Of Adhesively Bonded Joints, Aleric Alden Sanders

Mechanical & Aerospace Engineering Theses & Dissertations

Repair and reinforcement of composite honeycomb structures is an area of concern as higher demands are being placed on high strength, lightweight structural materials, such as carbon fiber reinforced plastics and corresponding honeycomb structures. A common issue with these structures is when a delamination in the facesheet may form and spread, leading to a failure scenario. An investigation of adding a through thickness reinforcement (TTR) to these structures at the sample level that undergo four-point-bending, tension, and joining methods is conducted throughout this thesis. The embedding of pultruded carbon fiber rods is found to be an ideal addition to composite …

Flexible Electrochemical Lactate Sensor, Peyton Miesse

Biomedical Engineering Theses & Dissertations

Lactic acid is a vital indicator for shock, trauma, stress, and exercise intolerance. It is a key biomarker for increases in stress levels and is the primary metabolically produced acid responsible for tissue acidosis that can lead to muscle fatigue and weakness. During intensive exercise, the muscles go through anerobic metabolism to produce energy. This leads to decreases in the blood flow of nutrients and oxygen to the muscles and increases in lactate production, which in turn cause lactic acidosis. Currently, changes in blood lactate concentrations are monitored by sensors that can be invasive via blood or wearable based sensors …

Truck Trailer Classification Using Side-Fire Light Detection And Ranging (Lidar) Data, Olcay Sahin

Civil & Environmental Engineering Theses & Dissertations

Classification of vehicles into distinct groups is critical for many applications, including freight and commodity flow modeling, pavement management and design, tolling, air quality monitoring, and intelligent transportation systems. The Federal Highway Administration (FHWA) developed a standardized 13-category vehicle classification ruleset, which meets the needs of many traffic data user applications. However, some applications need high-resolution data for modeling and analysis. For example, the type of commodity being carried must be known in the freight modeling framework. Unfortunately, this information is not available at the state or metropolitan level, or it is expensive to obtain from current resources.

Nevertheless, using …

Role Of Anisometric Particles In Ice-Templated Porous Ceramic Structure And Mechanical Properties, Mahesh Banda

Mechanical & Aerospace Engineering Theses & Dissertations

Open-cell macroporous ceramics have a significant impact on advancing various engineering endeavors such as bone-tissue engineering, lithium-ion batteries, filtration, thermal insulation, impact protection, etc. While pore orientation in conventional open-cell foams is random, in recent years, significant interest has grown in utilizing directionally porous ceramics in these applications to enhance performance. Ice-templating has emerged as a versatile technique that can synthesize directionally macroporous ceramics with low pore tortuosity. Although the fabrication is relatively straightforward, the challenge is that there are numerous variables associated with this technique, which can have significant effects on the final structure and macroscopic properties. As a …

Topology Control, Scheduling, And Spectrum Sensing In 5g Networks, Prosanta Paul

Electrical & Computer Engineering Theses & Dissertations

The proliferation of intelligent wireless devices is remarkable. To address phenomenal traffic growth, a key objective of next-generation wireless networks such as 5G is to provide significantly larger bandwidth. To this end, the millimeter wave (mmWave) band (20 GHz -300 GHz) has been identified as a promising candidate for 5G and WiFi networks to support user data rates of multi-gigabits per second. However, path loss at mmWave is significantly higher than today's cellular bands. Fortunately, this higher path loss can be compensated through the antenna beamforming technique-a transmitter focuses a signal towards a specific direction to achieve high signal gain …

Compaction And Residual Stress Modeling In Composite Manufactured With Automated Fiber Placement, Von Clyde Jamora

Mechanical & Aerospace Engineering Theses & Dissertations

Automated fiber placement is a state-of-the-art manufacturing process that allows for complex layup patterns and can quickly place, cut, and restart composite tows. However, with this type of manufacturing process layup defects are inevitable, and manufacturing defects propagate after curing. Process modeling is the considered approach for exploring the defect prediction. Two different but related works were conducted, which are the thermochemical and hyperelastic model and the residual deformation model. For the model before cooling, a hyperelastic model and a thermo-chemical were made to simulate the compaction and heat transfer. Temperature dependent properties that are a function of degree of …

Rotorcraft Blade Angle Calibration Methods, Brian David Calvert Jr.

Mechanical & Aerospace Engineering Theses & Dissertations

The most vital system of a rotorcraft is the rotor system due to its effects on the overall flight quality of the vehicle. Therefore, it is of importance to be able to accurately determine blade position during flight so that fine adjustments can be made to ensure a safe and efficient flight. In this study, a current calibration method focusing on the pitch, flap, and lead-lag blade angles is analyzed and found to have larger than acceptable error associated with the sensor calibrations. A literature review is conducted which reveals four novel methods that can potentially increase the accuracy of …

Diagnostic Studies Of Non-Thermal Atmospheric Pressure Nanosecond Plasma Jets, Shutong Song

Electrical & Computer Engineering Theses & Dissertations

Non-thermal atmospheric pressure plasma jets attract a lot of attentions due to its growing interest in plasma medicine. In this study, reactive species (e.g. excited He, O, OH) in a helium single-electrode non-thermal atmospheric pressure nanosecond plasma jet (APNPJ) driven by a nanosecond pulsed power supply have been studied via electrical measurements (e.g. voltage, current) and optical emission spectroscopy. It is shown that the gas temperature of the APNPJs remained near 300±50 K by fitting N₂(C-B) second positive system and OH(A-X) emission spectrum. Higher excited N₂+ (by a factor of 1.3) but less excited N_{2 …}