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Articles 1 - 30 of 1906
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An Empirical Study Of The Relationship Between Automation And Aircrew Accident Performance In High Performance Aircraft Operating In The U.S. Naval Shipboard, Richard Matthew Gensley
An Empirical Study Of The Relationship Between Automation And Aircrew Accident Performance In High Performance Aircraft Operating In The U.S. Naval Shipboard, Richard Matthew Gensley
Dissertations
The research described in this dissertation was an empirical study of cockpit automation and aircrew accident performance in high performance aircraft. The data set consisted of 3,249 accident records released by the U.S. Naval Safety Center and publicly available information for high performance aircraft based aboard U.S. aircraft carriers between the years of 1980 and 2013. Five conclusions resulted from this study. The first result was a demonstration that through statistical analysis, it is possible to assess if different aircraft over a prolonged period of time have been exposed to a common operating environment. The second result was that while …
Shocks And Cold Fronts In Merging Galaxy Clusters, Purva Diwanji
Shocks And Cold Fronts In Merging Galaxy Clusters, Purva Diwanji
Dissertations
Galaxy clusters, found at the nodes of the large-scale structures in the universe, are the most massive gravitationally bound and virialized structures in the Universe. They are formed via accretion, gravitational infall, and hierarchical mergers of smaller sub-clusters and galaxy groups. Mergers of galaxy clusters are the most energetic events in the Universe after the Big Bang, wherein the sub-clusters collide at velocities of ~1000km/s, releasing energy of the order of 10^(64) ergs. During such a merger, the galaxies and dark matter of both clusters interact only gravitationally and move unhindered through the region of the collision. This dissertation presents …
A Novel Method For Time-Based Synchronization Of Acquired Force And Motion Data, Darnisha Detraniece Crane
A Novel Method For Time-Based Synchronization Of Acquired Force And Motion Data, Darnisha Detraniece Crane
Theses
Enhancing the performance of flapping wing micro air vehicles hinges upon a thorough comprehension of the intricate interplay between wing kinematics and resulting forces. This understanding necessitates a method of synchronization capable of establishing a precise correlation of wing motion and force generation. The objective of this project is to develop a time-based synchronization method using existing hardware in the ATOM lab. Algorithms were developed to control the Vicon motion-tracking system and the ATI force sensor to achieve the synchronization of acquired data. Experimental testing was conducted to validate the algorithms and system architecture. Results from testing revealed a time …
Sms : A Smartwatch Application Suite For Mobility Assessment, Suresh Avula
Sms : A Smartwatch Application Suite For Mobility Assessment, Suresh Avula
Theses
Regular assessment of mobility can detect changes in physical health over time and discover underlying health issues. Some of these changes in mobility may indicate an increased risk of falls, which can lead to serious injuries. Identifying mobility changes can help prevent these incidents. Wearable technology can facilitate mobility tests at home and alert caregivers or medical professionals to any irregularities and promote proactive healthcare. Adoption of smartwatches with various built-in sensors like accelerometer and gyroscope creates new opportunities for wearable health monitoring. We developed the Smartwatch Application Suite to evaluate functional mobility using standard mobility tests: Timed Up and …
Unsteady Flow Characteristics Of A Normal Shock Wave And Associated Lambda Foot, Michael D. Sorrell
Unsteady Flow Characteristics Of A Normal Shock Wave And Associated Lambda Foot, Michael D. Sorrell
Theses
Shock wave interactions are important in a variety of engineering applications, ranging from gas turbines to rocket nozzles. There is much discussion regarding the sources of unsteadiness related to unsteady shock wave structure. This thesis investigates related interactions through spectral analysis of shock wave tracked positions, and instantaneous surface static pressure, temperature, and heat flux. A shadowgraph system for implementing shock wave tracking analysis is employed within a supersonic test section with an inlet freestream Mach number of 1.54. Unsteady surface static pressure and temperature variations are measured at streamwise locations along the bottom wall. Unsteady temperature data are used …
Methodology, Deployment, And Performance Of Pico Balloons In Antarctica, Todd Mckinney
Methodology, Deployment, And Performance Of Pico Balloons In Antarctica, Todd Mckinney
Theses
During the 2022/2023 Antarctic summer, eight pico balloon flights from Neumayer Station III unveiled insights into Antarctic troposphere/stratospheric winds (9 - 15 km AMSL). The most impressive flight lasted an astounding 98 days, completing eight circumnavigations of the Southern Hemisphere. Flight data indicated zonal velocities from -50 to 250 km/hr and meridional velocities of ±100 km/hr, with total wind speeds from 2.0 to 270 km/hr. Pico balloons can ascend due to convection, altering their float density. They also drift further south than larger stratospheric balloons, reaching latitudes close to the south pole. This study showcases the transformation of budget-friendly party …
The Effectiveness Of Online Video-Based Training Methods, Chloe L. Wood
The Effectiveness Of Online Video-Based Training Methods, Chloe L. Wood
Theses
Employee training is considered critical for organization success legitimacy. The present study investigated the effects of four different online training methods on post- test recall. Student participants from UAH viewed one of four types of videos covering diversity, equity, and inclusion concepts--generative scenarios in which participants generated a label for what the scenarios covered, descriptive scenarios that included a label, a control with scenarios, and a control with no scenarios. Scenarios involved school-based and work-based examples to assess how the relevance of context for student non-workers versus student-workers impacted recall. A repeated measures ANOVA revealed that across all four conditions …
Thermal Processing Of Al-Zn-Cu-Mg-Zr Laser Powder Bed Fusion Material For Increased Ductility, Jeffrey S. Gaddes
Thermal Processing Of Al-Zn-Cu-Mg-Zr Laser Powder Bed Fusion Material For Increased Ductility, Jeffrey S. Gaddes
Dissertations
Although the use of wrought high strength aluminum alloys is prevalent throughout aerospace systems, they often have long lead times and become difficult to source throughout the long lifecycle of aviation systems. Laser Powder Bed Fusion (LPBF) Additive Manufacturing (AM) provides opportunity to directly manufacture wrought equivalent aluminum products without forging supply chain challenges. If these LBPF components are made with the same aluminum material system with similar strength and ductility, they can be a direct replacement for traditionally manufactured components. However, existing 7xxx aluminum alloys are prone to cracking during fusion welding and therefore are not readily produced through …
Development Of A Continuum Damage Constitutive Model And Simulation For Brittle Materials In Space Infrastructure Application, Luis Eduardo Deganis
Development Of A Continuum Damage Constitutive Model And Simulation For Brittle Materials In Space Infrastructure Application, Luis Eduardo Deganis
Dissertations
The purpose of this work is to develop a continuum damage constitutive material model and apply it to structural response characterization of brittle materials for in-situ construction of space infrastructure. This research improves and expands the utility of the physics-based dominant crack algorithm (DCA) model in order to account for very low-strain rate phenomena in plain concrete structures. The DCA model is strain-rate dependent and has been effectively utilized for highly dynamic phenomena. The model has a strong basis in micromechanics and is able to capture the strain-softening response of brittle materials. The newly developed constitutive model can be easily …
Enabling Outer Planet Exploration : Performance And Feasibility Of Nuclear Thermal Propulsion For Rendezvous Missions, Saroj Kumar
Enabling Outer Planet Exploration : Performance And Feasibility Of Nuclear Thermal Propulsion For Rendezvous Missions, Saroj Kumar
Dissertations
Nuclear Thermal Propulsion (NTP) provides the compelling alternative between the chemical and electric propulsion systems for outer planet robotic missions. High-thrust and high-specific impulse (over twice the best chemical propulsion engine) NTP systems can enable outer planet missions that have been limited due to the large ΔV requirements. This dissertation identifies an enabling mission architecture and NTP engine thrust class for rendezvous missions to the Gas giant and Ice giant systems. The work presented in the dissertation demonstrates the performance impact of the NTP system and its feasibility for robotic missions using a systems engineering model driven by the model …
Characterization Of Size Effects In Additively Manufactured Grcop-42 And Their Influence On Mechanical Response, Gabriel Demeneghi
Characterization Of Size Effects In Additively Manufactured Grcop-42 And Their Influence On Mechanical Response, Gabriel Demeneghi
Dissertations
This study investigates size effects on microstructure, mechanical behavior, and fatigue performance of additively manufactured GRCop-42. Systematic analyses, encompassing changes on powder composition, wall thickness, and heat treatment, was conducted on specimens produced through laser powder bed fusion (L-PBF) and laser powder direct energy deposition (DED) techniques. L-PBF specimens exhibited a reduction in strength and elongation with decreasing thickness, attributed to increasing porosity as specimen’s thickness decreases. Conversely, in DED specimens, decreasing mechanical properties with thickness were associated to surface topography. Emphasizing the non-generalizability of size effects across AM methods. Size effects were also investigated on high cycle fatigue, as …
Microstructure Control Through The Use Of Gas Tungsten Arc Welding Based Additive Manufacturing, Benjamin M. Beeker
Microstructure Control Through The Use Of Gas Tungsten Arc Welding Based Additive Manufacturing, Benjamin M. Beeker
Dissertations
Additively manufactured (AM) parts are subjected to rapid and repeated localized melting, solidification, and reheating, which produces a heterogeneous microstructure. To homogenize the resulting heterogeneous microstructure that results from this non-equilibrium thermal cycling, ex-situ heat treatments can be used. However, this is intended to provide homogenous properties to the printed part, thereby not realizing one of the potential benefits of AM in providing site-specific properties such as fatigue resistance, wear resistance or high strength. This study explores the use of in-situ heat treatments to spatially control microstructure evolution, thereby controlling the location of specific mechanical properties. To guide the processing …
A New, Intuitive Method For The Design And Analysis Of Multi-Pass Cavities, Adam S. Mansor
A New, Intuitive Method For The Design And Analysis Of Multi-Pass Cavities, Adam S. Mansor
Dissertations
This dissertation develops a new analytical approach for designing and analyzing multi-pass cavities like the Herriott cell employing the graphical yӯ diagram approach. The new technique can be deployed in spectroscopy absorption detection, femtoseconds laser cavities, or any off -axis spherical mirror interferometers applications. Such a system can be uniquely designed and evaluated by entering a few parameters that define the required physics for the cell, the packaging size limits for the system and the probe beam size, plus two user selected parameters. The existing design method, developed by Herriott, is discussed and then the yӯ diagram method is presented …
Coronal Magnetic Field Extrapolation And Topological Analysis Of Multi-Scale Magnetic Structures For Solar Eruptions, Wen He
Dissertations
Solar eruptions are manifestations of strong solar activities which occur in multiple scales and vary significantly in observations. It has also been increasingly realized that some scenarios initially proposed for relatively large-scale eruptions may persist down to much smaller/finer scales, largely owing to increasingly high-resolution observations of the Sun. However, confirming the coherent magnetic structures on the Sun remains challenging due to the lack of direct coronal magnetic field measurement. This dissertation mainly focuses on the topological analysis of multi-scale magnetic structures embodied in different solar eruptions with available observations. It is achieved by reconstructing the 3D coronal magnetic field …
Design, Modeling, And Experimental Realization Of Tunable Fabry-Perot Nanocavities For Broadband And Narrow-Band Applications, Kirtankumar Pravin Dixit
Design, Modeling, And Experimental Realization Of Tunable Fabry-Perot Nanocavities For Broadband And Narrow-Band Applications, Kirtankumar Pravin Dixit
Dissertations
Efficient control of light absorption at the nanoscale has become a popular area of research, leveraging metal, semiconductor, and dielectric thin film technologies to engineer multilayer structures that modulate light through interference. A Fabry-Perot nanocavity can be configured with a dielectric or semiconductor layer sandwiched between two metal layers to exploit interference. This necessarily involves multiple optical paths through a spacer medium. The ensemble structures can be configured for anti-reflection, high-reflection, and dichroism. This dissertation is structured around four main objectives, each aimed at demonstrating the advanced capabilities of these nanocavities in manipulating light. The goals specifically focus on showcasing …
Benefits Of Quadratically Tapered Flexures For Mems Resonators And Gyroscopes, Brian Grantham
Benefits Of Quadratically Tapered Flexures For Mems Resonators And Gyroscopes, Brian Grantham
Dissertations
An investigation into the benefits of quadratically tapered flexures for MEMS resonators and gyroscopes is performed and compared to the traditional non-tapered flexure design. Quadratically tapered flexures exhibit constant strain along the outer edge of the flexure whereas non-tapered flexures have significant stress concentration near the base of the flexure. The investigation considers peak stress, thermoelastic damping (TED), nonlinearity, and sensitivity to manufacturing variations. The impact of inside corner fillets on peak stress, TED, and resonant frequency is also investigated. Five new anti-phase lever mechanism (APLM) configurations for resonators and gyroscopes are designed and analyzed using CoventorWare 10. Fabrication experiment …
Interactions Of Caffeine With Anticancer Drugs Studied By Nuclear Magnetic Resonance, Baylee Parish
Interactions Of Caffeine With Anticancer Drugs Studied By Nuclear Magnetic Resonance, Baylee Parish
Theses
Caffeine can form stacking through pi-pi interactions with aromatic anticancer drugs. While caffeine can reduce the toxicity of the anticancer drugs, caffeine can also reduce the efficacy of the anticancer drugs. Aromatic anticancer drugs, such as daunorubicin and irinotecan, work by intercalating into DNA. When caffeine binds to an anticancer drug, the new complex formed cannot easily intercalate into DNA strands. Through Nuclear Magnetic Resonance (NMR) spectroscopy, chemical shift values for pure caffeine, daunorubicin, and irinotecan, as well as, caffeine mixed with daunorubicin and irinotecan were analyzed. Different concentrations for the pure compounds and the mixtures were analyzed by NMR. …
Evaluating The Effects Of L-Pbf Printing Parameters On The Microstructure And Mechanical Properties Of Grcop-42, Elaina Walker
Evaluating The Effects Of L-Pbf Printing Parameters On The Microstructure And Mechanical Properties Of Grcop-42, Elaina Walker
Theses
GRCop-42 is a dispersion strengthened copper alloy of interest due to its high thermal conductivity. Since it is fabricated as a powder, it is adaptable to powder based, metal additive manufacturing (AM) processing. The chromium-niobium additives phase separate from the copper matrix and form strengthening dispersoids during the gas atomization process used to produce the powder. This study looks at the effect of the powder based, laser powder bed fusion (L-PBF) AM processing parameters on the resulting microstructure and mechanical properties. Builds were obtained from five different vendors, deposited using their best practice, for metallurgical and mechanical property evaluation. By …
Application Of A Scale Resolving Turbulence Model To A Jet In Supersonic Crossflow, Noah Schwalb
Application Of A Scale Resolving Turbulence Model To A Jet In Supersonic Crossflow, Noah Schwalb
Theses
The Partially-Averaged Navier-Stokes (PANS) methodology is applied to variable-density flow to derive the Blended PANS (BPANS) model. A supersonic jet-in-crossflow problem is numerically simulated using the BPANS model to show its capabilities in a variable-density flow with complex physics. The shock systems and vortex structures of this problem observed during experiments are numerically reproduced. The time-averaged Mach number and streamwise velocity contours show good agreement compared to LES and experimental data. The streamwise and wall-normal velocity profiles, wall pressure distribution along the flat plate, and trajectory of the jet are compared to LES and experimental data to show that BPANS …
The Impact Of The 2018 Camp Fire On Land-Atmosphere Interactions, Andrew C. Blackford
The Impact Of The 2018 Camp Fire On Land-Atmosphere Interactions, Andrew C. Blackford
Theses
Research on the effects of wildfire-induced changes in land use and land cover (LULC) on atmospheric processes is limited. This thesis presents a thorough analysis using satellite remote sensing and numerical modeling to examine how land-atmosphere interactions have been altered by the burn scar from the 2018 Camp Fire event in California. Satellite data reveals significant changes in surface characteristics affecting land-atmosphere interactions, such as land cover type, vegetation fraction (-0.12), albedo (+0.01), daytime temperature (+2.5 K), and roughness length (>-90%). Numerical modeling, based on satellite-derived LULC change scenarios, indicates notable shifts in net radiation (-0.2 MJ m-2), sensible …
Hierarchical Multi-Label Text Classification In Earth Science Datasets, Rajashree Dahal
Hierarchical Multi-Label Text Classification In Earth Science Datasets, Rajashree Dahal
Theses
This thesis addresses the challenging problem of hierarchical multi-label text classification and introduces a novel zero-shot approach that recommends the label up to the depth of hierarchy in which it is confident. In order to validate the efficacy of the proposed method, we experimented using various potential embedding models such as text-embedding-ada-002, mpnet-all, instructor embeddings, and nasa-smd-ibm-st on Earth science datasets. The experimental results reveal that all considered embedding models surpass the baseline model supervised learning classifier, demonstrating the superiority of the proposed zero-shot approach. This proposed solution can minimize the label imbalance problem typically observed in the supervised learning …
Curation And Analysis Of Ai Ready Environmental Justice Datasets : A Proof-Of-Concept Study, Paridhi Parajuli
Curation And Analysis Of Ai Ready Environmental Justice Datasets : A Proof-Of-Concept Study, Paridhi Parajuli
Theses
Equity and Environmental Justice (EEJ) advocates for unbiased distribution of environmental impacts across communities, regardless of social and economic characteristics. After extreme events like natural disasters, EEJ gains importance due to evident disparities in impact among communities. Addressing these injustices requires comprehensive datasets and analytical methods for quantification and resolution. While AI and advanced data analysis offer promising solutions, creating AI-ready EEJ datasets is challenging due to heterogeneity in the data surrounding EEJ. In this work, we focus on curating novel datasets for EEJ targeting a few recent extreme events - Maui Wildfire, Hurricane Harvey, and Hurricane Ida. We demonstrate …
Small Molecule Modulation Of The P75 Neurotrophin Receptor Attenuates Neurodegeneration In An In Vitro Model Of Parkinson’S Disease, Poshan Pokharel
Small Molecule Modulation Of The P75 Neurotrophin Receptor Attenuates Neurodegeneration In An In Vitro Model Of Parkinson’S Disease, Poshan Pokharel
Theses
The p75 Neurotrophin Receptor (p75NTR) is a multifunctional transmembrane protein expressed in distinct regions of the adult nervous system. p75NTR regulates various functions, including neuronal survival or apoptosis interacting with coreceptors Trk receptors or sortilin. Activation of p75NTR occurs through proteolytic processing, and we previously demonstrated that oxidative stress induces activation of p75NTR in LUHMES cells, a neuronal cell line derived from the human ventral mesencephalon. Dopaminergic neurons of the ventral mesencephalon are vulnerable to oxidative stress and neurodegeneration associated with Parkinson’s disease (PD). Thus, we evaluated the mechanisms behind p75NTR activation and its physiological implications in a PD model. …
Functionalizing Silicon Oxide Like Surfaces With Fatty Acids, Maman Sani Maman Brah Maman
Functionalizing Silicon Oxide Like Surfaces With Fatty Acids, Maman Sani Maman Brah Maman
Theses
The goal of this project was to make flat hydrophilic, silicon oxide-like surfaces hydrophobic. Using fatty acids in a wet chemistry approach. Glass, mica, and silicon wafer surfaces were cleaned with standard methods from the literature. The substrates were functionalized with oleic acid and stearic acid in ethyl alcohol. The solution concentration was held constant at 100 times a theoretical minimum concentration. The substrates were immersed at various functionalization times and various solution temperatures. Contact angle goniometer was used to measure the contact angle for water on the functionalized surfaces. The results confirmed that glass and oxidized silicon wafer surfaces …
Ambient Temperature Modelling With Ecostress And Private Weather Stations, Gaurav Khatri
Ambient Temperature Modelling With Ecostress And Private Weather Stations, Gaurav Khatri
Theses
This thesis explores the development and application of a novel data architecture for predicting ambient temperatures across US cities, focusing on integrating multi-source data i.e. ECOSTRESS land surface temperatures, urban surface properties, and crowdsourced weather data. The methodology is designed for scalability and adaptability across different urban regions, employing rigorous data quality control to enhance prediction accuracy. The validation of this model across diverse urban settings, demonstrated through rigorous RMSE comparisons and spatial mapping, validates its superiority over traditional models. Through experiments in diverse climatic conditions in Madison, Wisconsin, and Las Vegas, Nevada, the study assesses the model’s generalizability and …
The Effect Of Emotional Demeanor Of Adult Sexual Assault Victim Testimonies On Mock Jurors' Verdicts, Callie Ahearn
The Effect Of Emotional Demeanor Of Adult Sexual Assault Victim Testimonies On Mock Jurors' Verdicts, Callie Ahearn
Theses
Experiencing a sexual assault and testifying in trial are both highly emotional events that can influence a witness to display strong negative emotions. The display of emotion is referred to as the emotional demeanor and the present study examined the impact of a victim’s emotional demeanor on jury decision-making. Results revealed a main effect of crying during the direct examination with more guilty verdicts and higher pro-victim ratings (believability, credibility, and trustworthiness). Female participants provided higher pro-victim judgments on believability than male participants. Verdict reasoning demonstrated that participants had an idea of what they expected a rape victim to look …
Reduction Of Cognitive Load In Immersive Virtual Reality With Multisensory Cues, Daniel Wilson
Reduction Of Cognitive Load In Immersive Virtual Reality With Multisensory Cues, Daniel Wilson
Theses
This study investigated the effects of multimodal interfaces and immersive virtual environments on cognitive load. Participants played a first-person target shooting game with either a virtual reality headset or on a monitor, using visual, auditory-visual, and a haptic-visual interfaces. Performance and self-reported data about cognitive load and spatial presence were collected for each interface. The study found that both immersive environments and multimodal interfaces reduced cognitive load. Additionally, an interaction was seen such that multimodal interfaces were more effective at reducing cognitive load in immersive environments. These findings indicate that the addition of more modalities into interfaces, especially in highly …
Impact Of The Substrate Stiffness On Macrophage Function, Aaron Newchurch
Impact Of The Substrate Stiffness On Macrophage Function, Aaron Newchurch
Theses
This study explores macrophage cell function in healthy and diseased tissue that alters the synovial membrane housing fibroblasts and macrophages by examining how substrate stiffness impacts macrophage function. Current research suggests macrophages adapt, becoming more inflammatory in this environment. Divalent ions (CaCl2 or SrCl2) are used to adjust alginate hydrogel stiffness. The monocyte cell line THP-1 is transformed into macrophages through PMA, LPS, and IFNγ treatment within hydrogels, then cultured for 12 days. Divalent ions affect macrophage functionality; Sr2+ crosslinked hydrogels show higher viability, as well as an increased expression of M1 markers CD197 and IL1β, while M2 marker expression …
Interlacing Unstructured Data With Deep Neural Nets For Predicting Pervious And Impervious Land Cover Types, Srivani Athmakur
Interlacing Unstructured Data With Deep Neural Nets For Predicting Pervious And Impervious Land Cover Types, Srivani Athmakur
Theses
This research delves into the intricate task of delineating land cover types in Tallahassee-Leon County and emphasizes the need for detailed granularity beyond existing classification systems. Utilizing cutting-edge GIS data, the study harnesses the power of deep learning algorithms, including U-net, UNetPlusPlus, FPNnet, and DeepLabV3Plus. A unique approach, ”Interlacing Unstructured Data with Deep Neural Nets,” integrates shapefiles and Tiff images to enhance classification metrics such as mean intersection over union, pixel accuracy, and loss functions. The research aspires to significantly improve the precision of land cover classification, holding implications for urban planning and environmental management. By innovatively integrating unstructured data, …
Application Of A New Scale-Resolving Turbulence Model To Supersonic Retropropulsion Flows With Chemistry, Gabriel C. Nastac
Application Of A New Scale-Resolving Turbulence Model To Supersonic Retropropulsion Flows With Chemistry, Gabriel C. Nastac
Dissertations
Turbulent compressible flows are ubiquitous in many engineering applications of flight and propulsion. Computational fluid dynamics simulations are commonly performed to analyze these flows. Scale-resolving turbulence models inherently better capture various flow phenomena, including separation and mixing, as well as enable predictions of fluctuations, which can be critical for design compared to traditional steady-state turbulence models. In this work, new scale-resolving blended Partially-Averaged Navier-Stokes (BPANS) turbulence models are developed to account for compressibility effects and are employed to efficiently simulate turbulent compressible flows. Specifically, supersonic retropropulsion flows are investigated. Supersonic retropropulsion is a key technology for next-generation rockets. The new …