Engineering Commons^™

Hybrid Machine Learning And Comparison Error Minimization For Frequency Domain-Based Rapid State Estimation In Structures Subjected To High-Rate Boundary Change, James Scheppegrell

Theses and Dissertations

Dynamic forces and evolving structural boundary conditions pose challenges for various structural systems such as aircraft, orbital infrastructure, and energy harvesting devices. The design, evaluation, and functionality, of such systems can be aided through the collection and analysis of data. However, real-time decision-making for systems experiencing high-rate changes can pose unique challenges, if assessments are to be made accurately and rapidly enough to be relevant. In cases where the systems are well-defined and thoroughly understood, monitoring the frequency response can be instrumental in determining the state of structures subjected to high-rate structural boundary condition changes. This study focuses on investigating …

Investigation Of Shear Modulus And Material Damping Of A Lightly Cemented Silty Sand Representing Offshore Soil, Joshua Jeanjaquet

Theses and Dissertations

Offshore structures remain highly relevant, making the dynamic characterization of offshore soils critical. Since many offshore soils are cemented, understanding their response to dynamic loads is essential for developing accurate models that improve the reliability and cost-effectiveness of offshore structure designs. This study examines the impact of cement content on shear modulus, shear modulus reduction, shear wave velocity, and material damping of lightly cemented fine silty sand. A series of Resonant Column and Torsional Shear tests were conducted. The results were analyzed and compared to existing literature. The modified hyperbolic model was proposed to characterize the shear modulus and damping …

Investigating The Influence Of Volumetric Water Content In The Upper Layer Of Soil On Embankment Factor Of Safety, Kiera Rose Hughes

Theses and Dissertations

Geohazards, including landslides and embankment failures, pose significant risks to railway infrastructure, necessitating early recognition methods for effective risk mitigation. This research explores the relationship between the volumetric water content in the upper soil layer and the embankment's factor of safety (FOS) to improve early detection and stability assessment. A parametric analysis was conducted to evaluate how variations in the soil type (shear strength and hydraulic conductivity), slope geometry (angle and height) and recharge conditions (rainfall intensity and duration) affect the FOS. Using the GeoStudio software, seepage and slope stability analyses were performed for two baseline soils, as well as …

Supercritical Water Oxidation For Removing Pfas Contaminants: A Numerical Study, Ashley Joy Poyner

Theses and Dissertations

Per – and polyfluoroalkyl substances (PFAS) are a group of stable pollutants known for their long lifetimes and resistance to treatment methods used traditionally to remove other contaminants. PFAS and their ability to accumulate in both aquatic and terrestrial environments present threats such as detrimental effects to people and ecosystems due to their ability to penetrate entire systems. Though many methods are being explored to treat PFAS contamination in different systems, Supercritical Water Oxidation (SCWO) is a promising method for both removing and decomposing PFAS, with the ability to completely oxidize these persistent contaminants. This study is a numerical investigation …

Experimental And Numerical Analysis Of Fluidization Of Pelletized Activated Carbon Columns: Effects Of Glass Bead Retention Layer, Amin Nemati Tamar

Theses and Dissertations

In pressure swing adsorption (PSA) processes there is always a desire to process as much gas as possible in the smallest beds possible. This necessarily leads to velocities that, especially during pressure-changing steps, may exceed the adsorbent particle fluidization velocity within the bed. To prevent the possibility of bed expansion and fluidization bed retention systems are usually employed at the top of the bed in the form of dense beads, bags of the same or springs, otherwise the mechanical integrity of the adsorbent might become compromised. PSA process simulation, based on Archimedes’ force balance involving weight, buoyancy and the drag …

Ai, Blockchain, And Autonomous Innovation : Charting The Future Of Intelligent Enterprises, Shubham Gupta

Harrisburg University Other Works

In today’s digital economy, artificial intelligence (AI) and blockchain are twin forces driving transformative change. AI and blockchain each rose to prominence on their own, but together they hold the promise of revolutionizing how businesses operate and create value. AI systems can analyze massive datasets, automate complex decisions, and even mimic human learning and reasoning. Blockchain technology, on the other hand, enables secure and tamper-proof transactions by distributing records across a network, ensuring transparency and trust without relying on a central authority. The convergence of these technologies is ushering in new possibilities for automation, smarter decision-making, and secure digital transactions …

Dual Quaternions For Gravity Recovery Missions, Ryan Kinzie

Doctoral Dissertations and Master's Theses

A dual quaternion-based modeling, state estimation and control approach is introduced as a better alternative to the traditional methods which are currently utilized for gravity recovery missions. The proposed modeling and control approach was verified against and compared to the tangent bundle to Special Euclidean Group 3 through MATLAB simulations. The dual quaternion-based approach shows superior performance over traditional linearized and uncoupled methodologies, in both modeling accuracy of spacecraft translational position, and the ability to control the pose of a test mass relative to its host spacecraft. Utilizing data products from the Gravity Recovery and Climate Experiment Follow-On mission, a …

Exploring A Novel Adaptive Mesh Refinement Strategy For High-Speed Cfd, Arjun Jaishankar Vedam

Doctoral Dissertations and Master's Theses

Adaptive Mesh Refinement (AMR) techniques to efficiently and robustly achieve grid independent solutions on multi-element unstructured grids is a topic of practical interest within the CFD community.

The current effort focuses on the efficiency of a novel Adaptive Mesh Refinement (AMR) strategy that is developed and evaluated for transonic high-speed flows using Ansys Fluent. The algorithm for marking cells for adaptation is designed to systematically reduce local truncation errors based on the curvature of the primitive vector field. The algorithm for marking cells for adaptation is described in sufficient detail to be portable to other flow solvers that offer AMR. …

Modeling The Dynamics Of Flexible Aerospace Vehicles Using The Theory Of Functional Connections, Carlo Lombardi

Doctoral Dissertations and Master's Theses

Modeling and control of flexible vehicles is a topic of high interest in the aerospace field and a key challenge lies in finding accurate mathematical representations of the flexible dynamics of continuous elastic structures that allow simple integration into estimation and control algorithms. The answer was found in approximating the dynamics of these systems with sets of coupled Ordinary Differential Equations (ODE) for which a well-established estimation and control theory is available. Each of the techniques employed to achieve this goal is characterized by its own strengths and limitations. Hence, the main objective of this research is to develop the …

On The Provenance Of Software Systems: Automating Software Traceability With Knowledge Graph And Large Language Model Synergy, Tyler Procko

Doctoral Dissertations and Master's Theses

The present dissertation delineates a system that enables those engaged in software development to automatically generate and maintain project life cycle provenance. All projects are implemented and made manifest with the development of artifacts, e.g., papers, code files, etc. Tools exist to accelerate artifact creation, but little focus is paid to the processes that produce them. In terms of Ontology, or, from Ancient Greek, the study of being, the two most basic entities in reality are Continuant and Occurrent, or, roughly, “Artifact” and “Process”. This dissertation posits that for any created artifact, its process of creation, i.e., its life …

Developing Fixed-Bias Langmuir Probes For Multi-Point Constellation Deployments, Henry Carter Valentine

Doctoral Dissertations and Master's Theses

Since their initial development in the early 20th century, electrostatic Langmuir probes have proved invaluable in terrestrial and interplanetary ionospheric sounding applications. When deployed aboard rocket and satellite platforms, these probes yield high-cadence, in-situ measurements of key plasma parameters such as electron density, ion density, and electron temperature. Furthermore, the efficacy of Langmuir probes in characterizing the three-dimensional structure and dynamics of ionospheric plasmas can be augmented by the technique of multi-payload deployments. In this work, we discuss the design, development, and analysis of fixed-bias Langmuir probes constructed for two multi-point science campaigns: the Mars-bound, dual-satellite Escape and Plasma Acceleration …

Rookies To Aces: Investigating The Intuitiveness Of Pilot Interaction For Operating Evtol Aircraft, Shivani J. Patel

Doctoral Dissertations and Master's Theses

Electric Vertical Take-Off and Landing (eVTOL) aircraft introduce unique movement dimensions beyond traditional fixed-wing and rotor-wing aircraft, requiring novel control interfaces for pilot operation. This study examines the compatibility of gesture-based control movements across participants with varying flight experience levels. This study included a total of 60 participants across four groups; novices (no real or virtual flight experience, n=30), flight simulator gamers (n=10), fixed-wing pilots (n=10), and rotor-wing pilots (n=10). Participants viewed eighteen simulated first-person eVTOL aircraft movements (e.g. pitch, roll, yaw, heave, translations) assessing their intuitive gesture inputs for the different aircraft motions. Additionally, they were asked to sketch …

Framework For Integrating Industry Knowledge Into A Large Language Model To Assist Construction Cost Estimation, Prashnna Ghimire

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The construction industry generates a large amount of data across projects produced by digital devices, tools, and methods, and this volume is rapidly increasing. However, the industry lags behind in adopting data-driven technologies. On the other hand, the rapid advancement of generative AI (GenAI) in recent years, especially state-of-the-art large language models (LLMs), shows great potential and has been increasingly adopted in many industries; however, the construction industry is behind in adoption. While academic studies have proposed various machine learning applications for construction, industry implementation has lagged due to a disconnect between these proof-of-concept developments and practical industry needs. Also, …

Investigating The Discrepancies Between Acoustic And Radar Measurements Of Water Level Using Data Analysis And Computational Modeling, Ohiedul Haque Mohammad Asad

Civil & Environmental Engineering Theses & Dissertations

Observations indicate that there is a discrepancy between water level measurements from NOAA’s acoustic gauges and radar gauges. NOAA’s acoustic gauges use a downward-looking acoustic sensor that measures the instantaneous distance from the sensor to the water level. To create a calm water surface for measurements, the sensor is placed in a PVC tube that penetrates the water surface to a certain depth. This tube is called the stilling well. In this thesis, discrepancies in water level measurements from acoustic and radar sensors were explored through data analysis and computational modeling. Specifically, the correlations between the error, which is defined …

Effects Of High Temperature Compaction On 3d Printed Carbon Fiber Reinforced Polymer Composites, John D. Barber

Mechanical & Aerospace Engineering Theses & Dissertations

The aim of this dissertation was to study the effects of hot temperature compaction (HTC) upon the polymorphism and the mechanical behavior of an additively manufactured (AM), carbon fiber reinforced polyamide (PA6). Different pressure and temperature levels during HTC were tested to determine the overall effect upon the mechanical behavior and the material crystalline composition. Treated, carbon fiber reinforced PA6 samples were analyzed using differential scanning calorimetry, x-ray diffraction, thermogravimetric analysis, scanning electron microscopy, double cantilever beam testing and three-point bending testing. When considered with respect to as-printed samples, an HTC temperature of 190°C combined with 80 psi pressure resulted …

From Image Enhancement To Model Protection Integrating Generative Ai And Secure Learning In Computer Vision, Mohammad Shahab Uddin

Electrical & Computer Engineering Theses & Dissertations

This dissertation aims to address critical challenges in the field of computer vision and machine learning, focusing on three key areas: image translation, denoising, and model security. The research encompasses novel methodologies and models that significantly advance existing techniques. This dissertation will not only provide valuable contributions to the academic community but also hold significant potential for practical applications in domains ranging from surveillance to autonomous systems.

Consequently, this dissertation proposes three goals. First, we present new approaches for converting optical videos to infrared videos using deep learning. To apply powerful deep learning based algorithms for object detection and classification …

A Sysml V2 Implementation Of A Traceability And Verification Metamodel For “-Ilities”, Pacifique Munezero

Engineering Management & Systems Engineering Theses & Dissertations

Multidisciplinary knowledge and exchange of information are two of the most important aspects of complex system design within the Model-Based Systems Engineering (MBSE) domain. The next generation of systems modeling language, SysML v2, is being developed to improve the precision, expressiveness, interoperability, consistency, integration of the language concepts relative to SysML v1, and the implementation and maturation of MBSE approaches. This research focuses on using SysML v2 to model structured notations for -ilities, referred to as non-functional requirements (NFRs), to address how they can be treated with the same rigor as functional requirements and mapped directly and explicitly from the …

Wind Tunnel Automation For Propeller Testing, David Ricardo Lara

Mechanical & Aerospace Engineering Theses & Dissertations

An automated propeller test capability for the ODU Low-Speed Wind Tunnel Facility is demonstrated; implementing automation improved both ease of testing and quality of results. An experiment was performed with and without automation to compare results. Prior to this effort, propeller RPM and airstream velocity were manually controlled, leading to time consuming experiments. The setpoint for RPM had to be adjusted at each run to compensate for changes in airstream velocity.

LabVIEW, a graphical programming software, was used to develop the controllers and automation algorithm. A Proportional Integral Derivative (PID) control approach was developed to simultaneously control airstream velocity and …

Characterization Of Cure And Temperature Dependent Properties Of Filament Wound Composite Structures, Aaron Riley Sinkler

Mechanical & Aerospace Engineering Theses & Dissertations

Residual stress development in filament wound composites presents a critical challenge for the fabrication of thick composite structures exposed to elevated temperatures during operation. This study focused on determining temperature and cure dependent material properties to aid in understanding the residual stress build-up during the cure. Material characterization of a filament wound composite materials was performed by investigating thermo-chemical shrinkages in resin, lamina, and bi-lamina configurations. The coefficient of thermal expansion (CTE) of both the neat resin and the fiber was measured, and the gel point and chemical shrinkage of the neat resin were investigated. A filament wound unidirectional laminate …

Testing Autonomy: Hybrid Scenario Synthesis, Benjamin E. Hargis

Electrical & Computer Engineering Theses & Dissertations

Hybrid Scenario Synthesis merges static and adaptive techniques to generate interactions that rigorously assess autonomous performance under multi-factor testing. Multifactor scenarios employ multiple individual stimuli to rigorously test system responses in complex settings. Static Scenario Testing involves scripted test cases that simulate specific conditions or events. These scenarios represent typical situations an autonomous system might encounter. The benefits of static testing include early defect detection, focused review by trained experts, and efficiency. In multi-factor scenarios, however, statically defined scenario factors are not able to guarantee meaningful interactions as the presence of other factors may invalidate underlying assumptions regarding the system …

A Theoretical Framework For Examination Of Context In Complex System Governance, Meggan M. Schoenberg

Engineering Management & Systems Engineering Theses & Dissertations

“A complex system’s identity and viability are directly related and affected by its context. It is important to identify, monitor, and manage (or mitigate risk) system contextual elements” (Keating C. B. et al., 2022, p. 209). Despite this importance, there is very limited research and literature on complex systems context. This research seeks to expand our understanding of complex system context and improve our ability to govern complex technology development programs effectively. The ability to analyze complex systems and their problems is necessary for this improvement.

A “clear understanding of the specific complex system context is fundamental to the process …

Identifying Contributing Factors Of Black American Females’ Long-Term Persistence In Stem Education: A Qualitative Phenomenological Study, Chandra T. Oaks-Garcia

STEMPS Theses & Dissertations

The purpose of this study was to gain insights into contributing factors that have shaped the experiences of eight Black American females who pursued STEM education as they persisted from the secondary education setting to their collegiate setting in a STEM major. This qualitative phenomenological study collected data through in-depth semi-structured interviews with Black American female juniors and seniors studying at four different four-year institutions, all pursuing degrees in STEM-related fields. Demographic surveys and memo writing were incorporated to enhance the data analysis. To explore the lived experiences of Black American females in STEM education and identify factors that contributed …

Enhancing Iot Security Using Lightweight Machine Learning Algorithms: A Comprehensive Approach Using Ensemble Learning, Feature Selection, And Federated Transfer Learning, Khawlah Harahsheh

Electrical & Computer Engineering Theses & Dissertations

The rapid expansion of the Internet of Things (IoT) has introduced significant security vulnerabilities due to the resource-constrained nature of IoT devices and their exposure to cyber threats. Traditional security solutions are often infeasible due to the high computational and storage demands they impose. This dissertation presents a lightweight, AI-driven security framework that enhances IoT network resilience by integrating feature selection, ensemble learning, and federated transfer learning while maintaining data privacy and minimizing computational overhead.

The proposed framework consists of three primary components: Feature Selection for Intrusion Detection, which optimizes performance by reducing redundant data and improving detection accuracy with …

Valorization Of Industrial Wastes To Low-Carbon Minerals, Nandan Nag

Civil & Environmental Engineering Theses & Dissertations

This study concentrates on developing methods for utilizing industrial waste materials such as red mud and phosphate slag. In this study, an electrochemical process was developed for recovering iron metal powder from red mud. Red mud is a waste material from aluminum refineries. Although red mud can be utilized as a construction and building material, its use is becoming controversial due to its high metal content, which contributes to its toxicity. However, the high iron oxide content in red mud makes it a good feedstock for producing iron. In this project, we employed an electrochemical technique for extracting iron powder …

Network Analysis Of Sociotechnical Systems, Siva Kadiresan

Engineering Management & Systems Engineering Theses & Dissertations

Sociotechnical networks have become integral frameworks in the accomplishment of organizational objectives by increasingly diverse, cross-functional, and technology-enabled modern teams. In cross-disciplinary teamwork, multiple mediating and moderating factors appear to lend context to the effects of team diversity faultlines on team outcomes. In the several decades of research into teamwork from a network perspective, there has been a paucity of empirical studies that examine how team transition processes and cross-disciplinary connections influence the impact of faultlines on team performance. This study investigates the association among perceived teamwork effectiveness, transition processes, cross-functional team connections, and faultlines in the context of sociotechnical …

Streamer Discharge Simulation For Plasma-Assisted Combustion, Stuart Jairo Reyes

Electrical & Computer Engineering Theses & Dissertations

A common and successful method to achieve atmospheric pressure fuel-air plasma-assisted combustion is through repetitive ns pulsed discharges and dielectric-barrier discharge. The transient phase in these discharges is dominated by transport influenced by strong space charges produced by ionization fronts, this can be best represented by the streamer model. The function of non-thermal plasma in these discharges is to excite the species in the fuel-air mixture to produce radicals which accelerate the chemical conversion reactions which directly lead to temperature rise, ultimately culminating in ignition. Therefore, the characterization of the streamer and its energy partitioning is essential to developing a …

Modeling The Impacts Of Disruptive Events On Driving Behaviors, Transportation Safety, And Equity: Advanced Statistical Insights From The Covid-19 Pandemic, Xiaomeng Dong

Civil & Environmental Engineering Theses & Dissertations

This dissertation aims to understand how disruptive events —particularly the COVID-19 pandemic—affect driving behaviors, transportation safety and equity by leveraging advanced statistical modeling techniques and data from Virginia. This research pursues three overarching objectives. First, it employs multigroup structural equation modeling (SEM) to uncover the complex interrelationships among risky driving behaviors, injury severity, and pandemic-related factors, delineating the mechanisms through which COVID-19 has impacted crash outcomes via changing risky driving behaviors. Second, it leverages hidden Markov models to trace shifts in safety states over the pre-, during-, and post-pandemic periods, determining whether and when safety conditions return to pre-pandemic norms. …

A Formal Simulation Model For Discrete Rate Simulation, Thomas J. Tracey

Electrical & Computer Engineering Theses & Dissertations

Simulation is an essential tool for virtualizing systems by creating a representative model of real or hypothetical systems and observing how they change over time. Two predominant simulation paradigms include Discrete Event Simulation (DES) and Continuous Simulation, which both have their strengths and weaknesses. DES does not handle continuous state variables, while continuous simulation handles continuous state variables but encounters errors where these variables have discrete changes in their behavior. This difficulty between the two predominant simulation paradigms prompted the creation of a new simulation paradigm to cover this gap: Discrete Rate Simulation (DRS). DRS as a simulation paradigm focuses …

Wind Tunnel Testing Of A Novel Quadrotor Design, Oliver Marius Tobisch

Mechanical & Aerospace Engineering Theses & Dissertations

This study presents the test development and aerodynamic evaluation of the Quadfoil UAV, a novel quadrotor configuration featuring a central lifting body in the form of an airfoil to enhance forward-flight efficiency. Flight tests conducted by Virginia Tech demonstrated a 25% increase in endurance and a 32% improvement in range compared to conventional quadcopters, validating the aerodynamic benefits of this design. To further investigate its performance, a dynamically adjustable angle of attack model support system was developed for wind tunnel testing, enabling precise replication of in-flight conditions. The support system, controlled via LabVIEW, adjusts angle of attack based on real-time …

Low Dissolved Oxygen Operation Enhances Biological Phosphorus Removal In Wastewater Treatment, Haley Morgan

Civil & Environmental Engineering Theses & Dissertations

Biological phosphorus (bio-P) removal occurs when bacteria are exposed to anaerobic/aerobic conditions that stimulate polyphosphate-accumulating organisms (PAOs) to uptake phosphorus. In most treatment plants, dissolved oxygen (DO) concentrations in the aeration tanks are commonly at or above 2.0 mg O₂/L, which is often referred to as the most optimal aeration condition for bio-P. If bio-P can happen efficiently at lower DO (< 0.3 mg O₂/L), then the energy demand of aeration can be decreased appreciably. This research was conducted in a biological nutrient removal (BNR) pilot plant to assess the performance of bio-P at progressively lower DO operation. This …