Engineering Commons^™

Physics-Based And Data-Driven Constitutive Modeling Of Unsaturated Soils Under Multi-Physics Loading Conditions, Mohsen Ajdari

Theses and Dissertations

Understanding the behavior of unsaturated soils under multi-physics loading is crucial for addressing several challenges related to emerging geo-energy technologies, climate change, and geohazard mitigation. The main objective of this research is to enhance the state of the art for modeling unsaturated soils under multi-physics loading conditions through physics-based and data-driven approaches. Toward this objective, this dissertation is divided into two distinct yet interrelated parts. In the first part (Chapters 2, 3, and 4), thermodynamic principles are employed to develop new constitutive functions to describe soil suction and stress-dilatancy of unsaturated soils under temperature-dependent conditions. Building upon the insights gained …

On Topological Measures And Network Vulnerability Patterns: A Review And Comparative Analysis, Saviz Saei

Theses and Dissertations

Despite much hope for climate change to slow down or even reverse, younger generations face a future overshadowed by extreme events. The indisputable reality is that unless the United Nations establishes comprehensive and sustained climate justice policies, children today will experience five times more extreme events than those that took place a century ago. On Monday, July 3rd of 2023, an unprecedented peak in global temperatures was documented, marking the highest global temperature ever recorded, as the U.S. National Centers for Environmental Prediction reported. These increasing temperatures indicate the ongoing and intensifying phenomenon of climate change, which amplifies the frequency …

Investigation Of Coupled Fluid-Structure Interactions In Supersonic Flows, Seshendra Palakurthy

Theses and Dissertations

The skin panels used in high-speed flights are exposed to various types of loads, such as inertial, elastic, and aerodynamic loads. In addition, oblique shock impingement can cause flow separation and unsteady aerodynamic loading, which can reduce vehicle performance and result in acoustic noise and viscous heating. These loads, when combined, can result in a complex dynamic response, such as flutter. Flutter is characterized by sustained unsteadiness or structural vibrations. Although flutter might not be immediately harmful, it can lead to fatigue failure of the structural components. A vast amount of literature already exists on the panel flutter induced by …

Direct Methanol Fuel Cells Using Pure Methanol, Ryan Spragg

McKelvey School of Engineering Graduate Student Theses & Dissertations

Fuel cell technology has attained significant appeal as a form of renewable energy in recent years due to its diverse applications, various fuel types, and lower greenhouse gas emissions. Of the various fuel cell types, direct methanol fuel cells (DMFCs) hold a set of distinct advantages for stationary and small portable applications. These advantages include faster refueling compared to battery charging, high gravimetric energy density, and ease of production and use compared to hydrogen. However, the DMFC has numerous technical hurdles that prevent its widespread adoption into the commercial market. Namely, the slow reaction kinetics in the anode and the …

Custom Cathode Optimization For Electropolishing Additively Manufactured 316l Stainless Steel, Kasandra Escarcega Herrera

Mechanical Engineering ETDs

Laser powder bed fusion (LPBF) has become increasingly popular for its ability to rapidly manufacture complex metallic parts. However, the surface properties of as-built LPBF parts may degrade overall performance due to tortuous surface features. Consequently, post-processing like electropolishing (EP) to reduce the surface asperities is often needed for LPBF parts to perform as expected. Utilizing experimental and computational approaches, this project aims to more uniformly EP complex shaped parts made from LPBF 316L. For the experimental approach, parts with a three-dimensional T-shape were printed out of 316L stainless steel and EP using an acidic-based and a polyethylene glycol/NaCl-based electrolyte. …

Performance Evaluation Of Routing Protocols And Ml-Based Enhancements For Uav-Assisted Post-Disaster Communication Networks, Prachi Choudhary

Doctoral Dissertations and Master's Theses

During natural disasters, the existing communication systems collapse, and the disaster-affected areas become disconnected without any means of exchanging information. The collapse of existing communication networks poses challenges for First-Responders (FRs) in locating survivors during Search and Rescue (SAR) operations and for survivors to communicate for emergency aid. To alleviate post-disaster consequences and save lives, Uncrewed Air Vehicles (UAVs), commonly known as drones, can be employed to establish adaptable and reliable emergency communication networks. UAVs offer portability and rapid deployment, making them effective in crises. This thesis presents two main contributions: 1) Evaluation and Comparison of Routing Protocol Performance: The …

Ge/Sige Quantum Wells: Material For The Post-Moore Era, Troy Alexander Hutchins-Delgado

Optical Science and Engineering ETDs

This dissertation demonstrates high-quality germanium quantum wells on a 200 mm silicon wafer platform, enabling novel device possibilities. Partnering with a commercial silicon-germanium epitaxy supplier, we obtained shallow, undoped germanium quantum wells with high-crystalline quality, confirmed through x-ray diffraction, secondary ion mass spectroscopy, high-resolution scanning transmission electron microscopy, and energy dispersive x-ray spectroscopy. Hall bar devices fabricated on single quantum wells revealed that surface preparation can tune transport properties while maintaining peak mobilities around 10⁵ cm²V⁻¹s⁻¹. Manganese-germanide spintronic contacts were integrated via solid-state reaction, with contact quality assessed through Schottky diodes, transfer length …

Predictive Modeling And Sustainability Assessment Of Hydrothermal Liquefaction Of Seaweeds: A Techno-Economic And Life Cycle Analysis Approach, Micheal O. Asama

Mechanical Engineering Theses

This study presents comprehensive predictive models and an economic and environmental assessment of HTL for converting macroalgae into biofuels and valuable co-products. Predictive models were developed based on experimental kinetic data to simulate batch HTL of brown seaweed, capturing the yields of biocrude, gas, biochar, and water-soluble compounds as functions of key process variables, including temperature, time, pressure, and water-to-biomass ratio. Analysis of Variance (ANOVA) confirmed that temperature and residence time significantly affect biocrude yield, with an optimal yield of 23% achieved at 283°C, 200 bar, 54 minutes, and a 10:1 water-to-biomass ratio. The model’s predictive accuracy was validated with …

Data Intensive Method For Processing Defect Detection And Mitigation For Composites, Deepak Kumar

Doctoral Dissertations and Master's Theses

Composite manufacturing without processing defects is a crucial step in satisfying the production, performance, and quality requirements of composite materials in various industries. Autoclave processing enables manufacturing of high-quality composite parts with excellent mechanical properties, whereas additive manufacturing (AM) offers adaptability to complex designs and streamlined processes. However, each method presents unique challenges; despite the benefits, autoclave processes can still result in processing defects, and AM is particularly susceptible to processing anomalies owing to the novelty of the process. Ensuring the quality and reliability of composite manufacturing is essential to fully capitalize on the advantages offered by both techniques. Artificial …

Drainage Area Limitations Of Single Watershed, Peak Flow Estimates From Nrcs Methods, Timothy Alexander Maughan

Theses and Dissertations

Most roadway design sections of state Departments of Transportation predict peak flow for culvert design using Natural Resources Conservation Service (NRCS) TR-20 methodology. Even though the approach is more than 50 years old, there is no clear guideline for how large a single watershed drainage area may be while remaining appropriate for predicting peak discharge with this method. Our objective is to identify the drainage area where TR-20 peak flow predictions significantly deviate from flow frequency predictions. We aim to recommend to the Nebraska Department of Transportation (NDOT) a range of basin drainage areas appropriate for predicting peak flow using …

Traveling-Wave Vibration Control And Comparison Of Individuals With Insomnia And Good Sleepers Using Eeg Spectral Power And Sample Entropy, Joseph T. Lecheminant

Theses and Dissertations

This thesis explores the intersection of whole-body vibration (WBV) and neurophysiological analysis to improve sleep quality and understanding of insomnia. The work is divided into two primary areas: the development of a novel traveling-wave vibration system for sleep enhancement and the analysis of electroencephalography (EEG) metrics in individuals with insomnia versus good sleepers. A vibrating sleep system capable of generating programmable traveling-wave patterns is designed and prototyped. Through iterative development and user trials, the system enables highly controlled mechanical stimulation in the form of traveling-wave vibration. Key advancements include independent amplitude and speed modulation and customizable wave patterns. Simple wave …

An Experimental Investigation Of Signal Processing Techniques For Vibration-Based Structural Health Monitoring In Residential Buildings Subjected To Base Excitation, Fedaa Ali

Electrical Engineering Theses

Coastal regions, particularly in the southeastern United States, are consistently confronted with the ongoing threat of hurricane-induced damage to their buildings. Consequently, there is a pressing need to concentrate efforts on the evaluation and prediction of structural integrity and reliability in such environments. This is paramount for minimizing losses and enhancing public safety in the face of these challenging climatic conditions. Current structural health monitoring systems are typically customized for specific buildings, rendering them excessively expensive and impractical for residential structures. This research presents a comprehensive study of signal processing techniques and damage detection for an economical yet efficient structural …

Cellular Air Quality Sensors With Lora Backchannel A Robust Sensor Suited For Remote Deployment In Harsh Environments, Joseph R. Miera

Theses and Dissertations

Air quality significantly impacts health and overall quality of life, making its measurement essential. However, most affordable air quality devices are designed only for use within WiFi range and cannot handle extreme temperatures, limiting their usefulness for people in remote or extreme environments, such as regions with harsh winter climates. This limitation is concerning, as winter often brings worse air quality due to temperature inversions that trap pollutants and increase fuel burning for heating. Inversion is a problem as close to home as Utah Valley, and as far away as Ulaanbaatar, Mongolia. Most low-cost air quality sensors are not built …

Physics-Informed Transfer Learning For Process Control, Samuel Arce Munoz

Theses and Dissertations

In the realm of process control, managing complex systems with limited prior knowledge presents significant challenges, particularly in environments where traditional mechanistic models are either unavailable or computationally prohibitive. This work explores the integration of deep transfer learning with system identification and Model Predictive Control (MPC) to develop control strategies that are both data-efficient and computationally streamlined. Initially, Long Short-Term Memory (LSTM) networks are employed to create approximate MPC controllers by leveraging transfer learning from a source system to a target system, demonstrating that transfer learning can achieve comparable performance to traditional MPC methods with reduced training data. Building upon …

Securing Legacy Multivalue Pick Systems Modernized By Restful Web Service Apis, Jacob S. Lee

Theses and Dissertations

With more applications accessible on the Web, organizations with mission-critical legacy systems have had to find a way to stay relevant and competitive by modernizing with RESTful APIs. REST architecture, serving as a guideline rather than a strict protocol, offers significant advantages in terms of scalability, flexibility, and independence; however, its widespread adoption has also led to notable security vulnerabilities and weaknesses. Additionally, there is not one all-encompassing security testing methodology to follow when testing RESTful APIs. For this reason, a new security testing methodology was developed for legacy MultiValue Pick systems that implement the REST API component, MVConnect. The …

The Assessment Of Liquefaction Surface Ejecta Predictions On A New Large Dataset From The 2012 Emilia Romagna, Italy Earthquakes, Holten T. Flinders

Theses and Dissertations

The presence of a non-liquefied crust overlying a liquefied layer has been found to have a significant effect on sand ejecta and surficial liquefaction damage, as observed by Ishihara (1985). Following the 2010-2011 Canterbury seismic sequence in New Zealand, almost no foundation deformation occurred in areas with liquefaction susceptible soils overlain by at least a 3 m-thick crust [3]. In contrast, the 2012 Emilia-Romagna earthquake in Italy provided surface evidence of liquefaction despite 6- to 10 m-thick crusts. Several researchers have proposed liquefaction prediction models [e.g. LPI [6], Ishihara Curves [8], LSN [9], LPIISH [10] and the methods proposed by …

Enhancement Of Ambient Air Quality Index Forecasting Using Optimized Ensemble Model, Vanitha M

Theses and Dissertations

Forecasting ambient air quality is essential for environmental sustainability and public health, especially in heavily populated regions such as China, India, and the United States where air pollution remains a serious concern. Traditional forecasting models often struggle to accurately represent air quality data because of its complex patterns and nonlinear interactions. To address these challenges and improve forecast performance, this research proposes a comprehensive strategy that integrates parallel heterogeneous ensemble modeling with Bayesian optimization.

The study begins with a seasonal machine learning–based imputation technique (SeasonalMLImpute) designed to handle missing data in meteorological and air quality parameters. This method is evaluated …

In-Orbit Polymer Recyclers, Dargelys Buitrago Frías, José Muñoz González, Fon Saliki, Lamin Wright, Phuc Bui

Senior Design Project For Engineers

The International AstroTech Team proposes an innovative technology designed to revolutionize future space missions by facilitating in-space 3D printing using locally sourced materials. This cutting-edge technology focuses on developing an automated system capable of recycling polymers in space and transforming them into high-quality 3D printing filaments. By implementing this method, the technology addresses critical needs such as on-site resource utilization, sustainability, on-demand manufacturing, and resource efficiency. This approach not only reduces the dependency on Earth-supplied materials but also enhances the overall sustainability and operational flexibility of space missions. Consequently, it holds the potential to significantly advance the capabilities of space …

Strategic Responses For Unplanned Events, Tidjan Simpson

Harrisburg University Dissertations and Theses

The paper addresses the question, “Can dynamic, effective response plans be made for stakeholders of a manufacturing line dealing with unplanned events at a manufacturing line, irrespective of an individual’s unique subject matter expertise? Prior research in manufacturing-related environments has indicated the existence of a high frequency of unplanned events. When not responded to efficiently, they can result in reduced financial efficiency and employee overwhelm. Through collection and analysis of interviews conducted with stakeholders in the manufacturing environment, a possible means of efficiently addressing unplanned events can be found or synthesized to help stakeholders navigate uncertainty in the manufacturing environment …

Combining Project Management Methods For Faster Software Delivery, Subhradeep Biswas

Harrisburg University Dissertations and Theses

The impact of the hybrid project management technique combined with lean principles in software organization is the main topic of the proposed thesis. The instability inherent in software projects has led to the rise in popularity of the agile approach. However, according to specialists in project management, an agile approach alone won't guarantee a project's success. When executing software projects, almost all project managers combine the agile approach with the waterfall methodology. Nevertheless, a number of investigations discovered that the hybrid strategy is frequently not failsafe. In this field of study, combining lean and hybrid project management is a topic …

Using Additive Manufacturing To Characterize Effects Of Sparse Infill Density And Sparse Infill Pattern On The Compressive Properties Of Short Strand Carbon Fiber Infused Petg, Luke C. Salisbury

Honors Theses

The advent of additive manufacturing has revolutionized the prototyping, design, and manufacturing of new and innovative products. Through the use of Fused Deposition Modeling (FDM), parts can be manufactured using different sparse infill percentages (the percentage of void space within a printed object) and sparse infill patterns (the lattice structure of material within the object). Through the manipulation of these variables, the same material and part can have different compressive and flexural properties. In addition to sparse infill, the thermoplastics used in fused deposition modeling can be reinforced with carbon fiber strands to create a printable composite material capable of …

The Role Of Qa Automation In Eliminating Waste In Project Teams, Ejiro Esiri

Harrisburg University Dissertations and Theses

This study explores the impact of Quality Assurance (QA) automation on reducing waste in Search Engine Optimization (SEO) projects within enterprise organizations. Manual QA processes often result in bugs and defects that negatively affect project quality and business outcomes. Although automated QA testing promises improved accuracy and fewer errors, its implementation and effectiveness in SEO projects have yet to be thoroughly researched. This study uses qualitative research methods, including surveys of SEO professionals, QA specialists, and project managers in enterprise organizations, to examine how automated QA testing influences the performance and outcomes of SEO projects. The results show that companies …

Effect Of Laser Textured Surface With Different Patterns On Tribological Characteristics Of Bearing Material, Paul Joshua S

Theses and Dissertations

This research work determines the wear rate and friction characteristics of bearing material under different laser textured surface conditions. Chrome steels are used in bearings since they possess high strength and wear resistance. However, when those parts are in service, failure happens due to sliding friction before the lifetime. To improve the durability of the American Iron and Steel Institute (AISI) 52100 chromium steel, in this work, the effect of laser surface texturing (LST) was analysed.

With the different pattern of circle, ellipse, groove and grid were produced on the sample surface, the wear behavior was investigated using the pin …

Generative Ai-Based Optimized Recommender System For Debt Collection Using Large Language Models, Keerthana S

Theses and Dissertations

Reducing the percentage of defaulters who often skip payments throughout the debt collection process might help minimize losses in the banking industry. The debt collection process should be optimized to reduce the rate of defaulters and improve collection rates. Traditional Machine Learning algorithms focused on credit risk analysis, defaulter prediction, and forecasting the recovery rate of debt collection. Researchers are not currently prioritizing the analysis of debt collectors’ performance. The debt collector’s primary responsibility is to retrieve outstanding debts from consumers on behalf of the debt collection firm.

Examining debt collectors’ performance is essential to enhance collection efficiency in the …

Sustainability Assessment Of Photovoltaic Cells In Cross-Functional Applications, Achyuth Ravilla

Dissertations and Theses

Achieving the G7 countries' net-zero emissions target by 2050 requires integrating photovoltaic (PV) systems into diverse cross-functional applications that support sustainable energy transitions across multiple sectors. This dissertation explores the economic and environmental sustainability of three such applications: agrivoltaics, lower-dimensional materials in perovskite solar cells, and PV-electrochemical water-splitting technologies for hydrogen production. Employing life cycle assessment (LCA) and techno-economic analysis (TEA), we address the knowledge gap in comprehensive evaluations of PV-integrated solutions.

The first chapter assesses agrivoltaic systems (AVS), which combine PV systems with agriculture to mitigate land-use conflicts while enhancing food and energy production. Findings indicate that AVS designs, …

Heat Transfer In Tightly Packed Cylinder Arrays, Martin Kovachev

Doctoral Dissertations and Master's Theses

Cylindrical arrays with a cross flow are commonly used for heat transfer augmentation within an internal channel. In most applications, the cylinders have a spacing of over 2 diameters (2D) between their center points in both the lateral and downstream directions. One option for battery thermal management in hybrid/electric aviation is to use cylindrical batteries packed in arrays with an applied cross flow. In the context of aviation, it is important to maximize space and weight savings. Tightly packing these cylinder arrays with a spacing of under 2D in both directions would save on both of these yet have not …

A Low-Complexity Algorithm For Trajectory Generation In The Three-Body Problem, Brian P. Baker-Mcevilly

Doctoral Dissertations and Master's Theses

The Cislunar realm holds intrinsic value for scientific, commercial, and military applications as numerous entities have begun to invest resources into the expansion and utilization of the region. As the Cislunar region continues to grow, there is an escalating need for efficient methods of trajectory generation in this multi-body dynamical system for computationally limited systems. Thus, a low-complexity classical algorithm is proposed to achieve accurate orbital trajectories in the three-body problem. The proposed algorithm solves a polynomial interpolation problem, formulated using state measurements, through the unique decomposition of a dense system into sparse matrices. Several relevant Cislunar trajectories are simulated …

Propagation Modeling Of Terahertz Reflections And Reflector Design For Mimo Channel, Thanh Ngoc Dan Le

Dissertations and Theses

Wireless communication has transformed connectivity, enabling seamless access across devices without physical constraints. Terahertz (THz) frequencies, ranging from 100 GHz to 10 THz, promise high-bandwidth channels crucial for applications like IoT and virtual reality. However, deploying THz communication faces challenges due to significant propagation limitations such as high attenuation and environmental absorption. The motivation behind this research is to develop a comprehensive understanding of THz propagation dynamics and utilize reflective surfaces to create multipath environments for an improvement in the capacity performance of MIMO channels.

This research investigates the potential of Multi-Input Multi-Output (MIMO) channels at THz frequencies to overcome …

Applying Positive Unlabeled Learning Techniques And Using The Kullback-Leibler Divergence To Improve Geothermal Surveying Assessments, Martín Thomas Rodriguez

Dissertations and Theses

As we face the current climate crisis, the discovery of geothermal energy resources has the potential to greatly reduce our dependence on fossil fuels worldwide. However, the development of any new energy infrastructure is expensive and depends on the willingness of energy agencies and developers to make initial investments based on calculated risk measures. One such measure, called geothermal favorability, is the likelihood that a site has conditions favorable for geothermal systems containing recoverable energy potential. Its prediction from existing geophysical datasets proves to be a nontrivial task. The prediction of geothermal favorability can be framed as a binary classification …

Understanding The Role Of The Heat Transfer Coefficient Between Tool/Workpiece Interface During Friction Stir Welding, Matthew Goodson

Theses and Dissertations

The heat transfer coefficient is a key parameter in modeling friction stir welding and has yet to be measured experimentally. The importance of this parameter was shown through validating friction stir models on both sides of the tool/workpiece interface. Both a transient plunge and a steady state model were validated by matching experimental temperatures. The steady state tool temperatures were matched (with in 2.5%), but the steady state workpiece temperatures were off by around 20%. The transient model of the FSW plunge showed the effect of varying the ℎ𝑊/𝑇 on workpiece temperatures and tool temperatures. Two methods were looked at …