Engineering Commons^™

Numerical Investigation On Lightning Survivability And Residual Strength Of Scarf-Patched And Z-Pinned Cfrp Composites, Logan Hales

All Graduate Theses and Dissertations, Fall 2023 to Present

Carbon fiber reinforced polymer (CFRP) composites are critical in aerospace applications yet remain vulnerable to lightning strikes due to orthotropic electrical conductivity and poor thermal resistance. Over the past decades, lightning-strike damage in pristine CFRP has been extensively investigated. However, the response of damaged and subsequently repaired laminates remains poorly understood, raising concerns about the structural integrity of repaired aircraft. This study aims to develop a sequentially coupled thermo-structural modeling framework to quantify how two common composite repair strategies (scarf patching and z-pinning), along with patch size, pin material, and configuration, influence lightning-induced damage and the residual flexural strength of …

Developing Fragility Curves For Steel Special Moment-Resisting Frames In Utah, Olivia P. Murphy

All Graduate Theses and Dissertations, Fall 2023 to Present

Major seismic events along the Wasatch Fault represent a serious threat to Utah's residents and built environment. Engineers currently rely on a statistical approach that calculates earthquake ground shaking based on probabilities of various events occurring over extended time periods. This method informs how strong new buildings must be constructed. However, many structural engineering professionals in Utah worry that this probability-based approach may significantly underestimate the actual ground shaking compared to an alternative method that examines the largest possible earthquake a fault can generate. The substantial differences between the two analytical approaches raise fundamental concerns about whether existing construction standards …

Validity Of The Schrage Equation In Prediction Of Evaporation Rate Of Liquid N-Dodecane In High-Pressure Nitrogen Gas: A Molecular Dynamics Study, Wazih Tausif, Jordan Hartfield, Md Amin Haque, Zhi Liang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Evaporation of liquid fuel in a high-pressure air is a process that critically influences fuel–air mixing in advanced propulsion systems. In this work, we use molecular dynamics (MD) simulations to study the validity and accuracy of the Schrage equation in quantifying the evaporation and condensation rates of n-dodecane (a diesel surrogate) in air (approximated as N2 gas) with gas pressure varying from 0 atm to above the critical pressure of n-dodecane. The MD simulation results show that the evaporation coefficient (αe) is higher than the condensation coefficient (αc) at the evaporating n-dodecane surface and is lower than αc at the …

Mechanisms Of Synergy Between Nanosecond Pulsed Electric Field (Nspef) And Cold Atmospheric Pressure Plasma Discharge (Cap) In Pancreatic Cancer: The Role Of Ros-Mediated Oxidative Stress And Apoptosis, Zobia Minhas

Biomedical Sciences Theses & Dissertations

Pancreatic ductal adenocarcinoma is a highly lethal malignancy characterized by poor prognosis and resistance to conventional therapies. Novel treatment strategies are needed to overcome this resistance. Non-thermal physical modalities, including nanosecond pulsed electric field (nsPEF) and cold atmospheric pressure plasma discharge (CAP), have emerged as potential anticancer approaches; however, the mechanisms underlying their combined effects remain unclear.

This study evaluated whether nsPEF enhances CAP-induced cytotoxicity and investigated the associated molecular mechanisms using the murine Pan02 pancreatic cancer cell line. Cell viability was assessed by WST-1 metabolic activity assays and electric cell–substrate impedance sensing (ECIS). Intracellular reactive oxygen species (ROS) were …

A Novel Approach To Creativity Assessment: Forced Pairwise Ranking With Large Language Models, Phillip R. Gregory Jr

Master's Theses

Assessing creativity at scale remains a persistent challenge in cognitive science, as human raters are costly, slow, and often inconsistent in their judgments. This thesis introduced a novel framework for automated scientific creativity assessment using forced pairwise ranking, in which fine-tuned large language models compared response pairs and determined which was more creative. Five empirical studies were conducted using Llama-2-7B and Llama-2-13B models adapted via LoRA fine-tuning and benchmarked against human scored responses from the Scientific Creative Thinking Test. A regression baseline achieved Pearson �� = .74 on the test set, matching the human inter-rater ceiling reported in the literature. …

Undergraduate Design Spine For Biological Systems Engineering And Agricultural Engineering, David Mabie, Derek M. Heeren, Deepak R. Keshwani, Heidi A. Diefes-Dux, Nicole M. Iverson, Rachel Padrnos, Greg Bashford, Taryn King, Jenna Hefley, Curtis L. Tomasevicz

Department of Agricultural and Biological Systems Engineering: Presentations and White Papers

Engineering education is undergoing a shift toward preparing graduates with demonstrated capabilities that integrate technical knowledge, durable skills, and the ability to adapt in a rapidly evolving professional landscape. This paper describes a comprehensive redesign of the undergraduate curriculum in Biological Systems Engineering (BSEN) and Agricultural Engineering (AGEN) at the University of Nebraska–Lincoln. The redesign is grounded in a “Design Spine” framework, which distributes and scaffolds design experiences across all four years of the program to support progressive development of problem solving, systems thinking, communication, and professional skills. The curriculum is organized around clearly defined capabilities and threads that connect …

Assessment Of Super Absorbent Polymer In Soybean Cultivation Under Variable Irrigation Conditions In Nebraska, Ankit Chandra, Abia Katimbo, Ronaldo Marchezan, Martha Nabaggala

Department of Agricultural and Biological Systems Engineering: Presentations and White Papers

Water limitation is a primary constraint to soybean productivity in both irrigated and rainfed systems. Soil-applied superabsorbent polymers (SAPs) have been proposed as a strategy to buffer crops against episodic drought stress; however, their physiological and agronomic performance under varying irrigation regimes remains insufficiently quantified. Here, we evaluate three biodegradable polymer formulations: broader granules (BB), original granules (OG), and powder (PWR) applied at low (17.7 lb/ac) and high (120 lb/ac) rates under full (100% ET), reduced (50% ET), and no irrigation conditions in western Nebraska. Polymer application had negligible effects under full irrigation, with yields comparable to untreated controls. Under …

Design And Reliability Analysis Of A Radiation-Tolerant On-Board Computer System For Martian Surface Missions, Jack Ryan

Master's Theses

Space environments present complex challenges for electronic devices, perhaps most notably in the form of radiation effects; the natural protections provided by Earth’s atmosphere and magnetosphere are largely absent in deep space and extraterrestrial environments, making single-event effects (SEE) a critical concern. Although radiation-hardened components offer near-immunity to SEE, they possess tremendous drawbacks in both cost and performance. To circumvent such issues, this thesis investigates the feasibility of leveraging a commercial-off-the-shelf (COTS) device, the AMD KRIA K24 system-on-module (SOM), for use in Martian surface missions.

Detailed models were used to predict SEE rates in the system, and system-level fault tree …

Improving Fairness On Semantic Segmentation Using Large Language Models, Samuel E. Burggraf

Electrical & Computer Engineering Projects for D. Eng. Degree

As machine learning systems are increasingly integrated into critical decision-making processes, ensuring fairness in their design and implementation has become a significant concern. While fairness research has primarily focused on specific protected attributes, less attention has been given to spatial fairness, which can affect individuals at specific locations. If fairness is not addressed, models may systematically underperform in certain regions or across populations which can lead to unequal access to accurate predictions and potentially biased decision-making. Fairness considerations should extend across all machine learning applications to align with the National Institute of Standards and Technology (NIST) guidelines of fair and …

Effects Of A Passive Assistive Hamstring Device On Overground Running Kinematics And Hamstring Activation., Quinn Castner

All Theses

Hamstring strain injuries are among the most common and recurring injuries in sports, occurring most often during the terminal swing phase of gait. Despite progress in rehabilitation, the incidence of injury has only increased, suggesting a need for a novel intervention. We designed a passive, assistive, wearable device with two specific criteria in mind: to offload the hamstrings during running, and do so without hindering normal kinematic patterns. The device consists of an adjustable elastic band anchored proximally at the waist and distally just above the ankle joint center. It stretches and shortens with the hamstrings, providing passive hip extension …

Neural-Network-Based Modeling Of Grid-Forming Inverters, Jacob D. Levesque

All Theses

Renewable energy production has grown significantly in recent years and continues to expand, resulting in an increasing number of inverter-based resources (IBRs) in the grid. As the number of IBRs in the grid continues to grow, grid-forming (GFM) inverters are becoming increasingly popular due to their ability to regulate voltage and frequency, providing increased grid stability and enabling islanding. As GFM inverters become more widely used in power systems, accurate and efficient models of their behavior are needed for system design purposes.

Emerging advances in neural networks have led to research on computationally efficient neural-network-based (NN-based) modeling approaches for inverters. …

Fluorescence-Based Quantification Of Hepatic Ldl Uptake And Donor Hepatocyte Engraftment Using Atto 700–Labeled Ldl, Victor Agustin Cortes Flores

All Theses

Familial hypercholesterolemia (FH) is an inherited disorder characterized by elevated low-density lipoprotein cholesterol (LDL-C) that increases the risk of premature atherosclerotic cardiovascular disease. In severe FH, including low-density lipoprotein receptor (LDLR), hepatic LDL clearance is profoundly impaired and many lipid lowering treatment strategies have limited effectiveness. Current advances in ex vivo CRISPR–Cas9 hepatocyte gene editing in vivo and ex vivo approaches for treatment of FH are under development.

However, a central barrier to translation is the ability to quantitatively measure the percentage of healthy gen edited hepatocytes in the liver while simultaneously assessing functional hepatic LDL handling. This thesis establishes …

Increasing The Number Of Injections Per Cycle In A Gasoline Compression Ignition Strategy: An Experimental Study, Joshua Murray

All Theses

Gasoline Compression Ignition (GCI) is an advanced compression ignition strategy which utilizes the high octane number of gasoline to improve diesel soot and NOx emissions by enabling partially premixed injections of fuel. GCI work in the literature typically uses single, double, or triple injection strategies, with higher numbers of injections noted for their ability to achieve low MPRRs, improved soot and NOx emissions, and higher efficiency. Thus, this study extends the literature by evaluating quadruple and quintuple injection strategies for continued improvement in engine efficiency and emissions.

The experiments in this work are conducted on a heavy-duty Detroit Diesel DD13 …

Exercise-Induced Muscle Damage As A Model For Exploring The Effects Of Pain On Gait, Sydney Savage

All Theses

Persistent gait asymmetry following anterior cruciate ligament reconstruction (ACLR) is a recognized contributor to post-traumatic knee osteoarthritis, yet the independent role of pain in driving altered movement patterns remains poorly understood due to confounding factors inherent to clinical populations. This study used exercise-induced muscle damage (EIMD) as a controlled experimental model to isolate the effects of musculoskeletal pain on gait, independent of kinesiophobia, structural damage, and proprioceptive disruption. Eighteen healthy adults underwent unilateral eccentric calf-raise protocols to induce delayed onset muscle soreness (DOMS), with gait assessed at baseline, 48 hours, and 168 hours post-exercise using bilateral inertial measurement units. Outcomes …

Design And Development Of A Perfusable Hydrogel Platform With Bioprinted Human-Endothelialized Microvascular Channels, Calvin A. Chernyatinskiy

All Theses

We developed an integrated bioprinting and perfusion platform to generate vascularized hydrogel constructs that support perfusable microchannel networks. Multiple hydrogel formulations, sacrificial ink systems, device geometries, and perfusion conditions were systematically evaluated to optimize print fidelity, mechanical stability, and cellular compatibility. Internally gelling alginate–calcium carbonate hydrogels were identified as a robust matrix, providing tunable gelation kinetics and structural stability during embedded printing. In parallel, Pluronic F-127 fugitive ink enabled reliable fabrication of continuous hollow channels due to its shear-thinning behavior and efficient post-print removal.

The finalized platform integrates stereolithographically fabricated perfusion chambers with extrusion-based bioprinting to produce three-dimensional, perfusable vascular …

Exploration Of Real-Time Power Electronic Simulation On Amd Npu, Shouyu Du

All Theses

The rapid electrification of the automotive and data center sectors has created a critical demand for high-fidelity, real-time simulation of complex power electronic systems. While Hardware- in-the-Loop (HIL) simulation on Field-Programmable Gate Arrays (FPGAs) is the current industry standard, it presents significant challenges regarding development complexity and memory limita- tions. This dissertation investigates the feasibility of utilizing Neural Processing Units (NPUs)— specifically the AMD AI Engine (AIE) XDNA2 architecture—as a novel platform for real-time, deterministic circuit simulation. This study establishes a comprehensive automated modeling framework based on graph theory and Massarini’s method to derive linear state-space representations for arbitrary circuit …

Implementation Of A Local Llm Serving System For Agentic Ai, Zhiheng Ni

All Theses

This thesis presents a system that allows large AI models to run directly on personal devices instead of relying on cloud servers. Recent advances in artificial intelligence, especially large language models (LLMs), have made it possible to build powerful applications such as chatbots, coding assistants, and intelligent agents. However, most of these systems run in the cloud, which raises concerns about privacy, latency, and cost.

To address these issues, this work develops a local AI serving system that runs efficiently on a specialized hardware component called a Neural Processing Unit (NPU). The system provides a unified interface that supports multiple …

Electrochemical Reduction Of Carbon Dioxide By In-Situ Generated Hydrogen At Porous Cu-Fe Foam-Like Catalysts: Efficiency Towards Formic Acid Formation, Aya Saada, Attia Attia

Biochemical Engineering

No abstract provided.

Bridging The Gap: A Gap Analysis Of Commercial Pilot Training And Emerging Advanced Air Mobility Training Needs, Yarisse Adorno-Oyola

Theses and Dissertations

The integration of Advanced Air Mobility (AAM) into the national airspace presents new challenges for pilot training that are not adequately addressed by current commercial flight training standards. AAM aircraft, such as electric vertical takeoff and landing (eVTOL) aircraft, differ significantly from conventional aircraft in terms of design, propulsion, and automation. As a result, pilots will require new training that goes beyond the traditional fixed-wing or rotorcraft training offered under 14 C.F.R. Parts 61 and 141. The current study conducted a gap analysis to evaluate the alignment between current commercial pilot training and AAM's emerging training needs. Deficiencies in current …

2026 Spring Graduate Recognition Program, Propulsion Research Center, Robert Frederick

PRC Graduate Recognition

This program includes the graduate recognition program for spring 2026. Includes photographs, upcoming events, recent publications, and student profiles.

Introduction To The Special Issue On Computer Modeling For Future Communications And Networks, Wenbing Zhao, Pan Wang

Electrical and Computer Engineering Faculty Publications

No abstract provided.

Enhancing Reliable Performance Of Microgrids With Autonomous Control Of Distributed Energy Resources, Sahand Liasi

All Dissertations

This dissertation presents a comprehensive investigation into enhancing the reliability, efficiency, and autonomous operation of modern power networks through advanced microgrid integration and control strategies. The research addresses critical challenges across three interconnected domains: microgrid control, thermodynamic modeling of heat recovery system (HRS), and optimal distribution network reliability.

In the realm of microgrid control, this work introduces novel methodologies for grid forming inverter-based resources (IBRs). A significant contribution is the development and validation of an "Auto Frequency Change" controller, which drastically reduces microgrid synchronization time with the main grid from several minutes to approximately four seconds, with theoretical potential for …

Development And Validation Of The Ampere Scale: Measuring Adaptive And Maladaptive Perfectionism In Engineering Students, Haleh B. Brotherton

All Dissertations

Perfectionism refers to the inclination to set very high expectations for oneself, which can at times encourage personal development and at other times lead to stress and a sense of pressure. Perfectionism is widely observed among engineering students; however, instruments that distinguish adaptive striving from concern-driven tendencies in the engineering context remain limited. My study is based on the development and validation of the AMPERE (Adaptive and Maladaptive Perfectionism in Engineering) scale through a three-phase process: (I) expert review with two domain experts to establish content validity; (II) cognitive interviews with seven undergraduates to refine wording and interpretability; and (III) …

Generative Ai Of Breast Cancer Progression In Gene Expression Space, Xusheng Ai

All Dissertations

Breast cancer is one of the most common and deadly cancers in the world. Although doctors can use gene activity data to better understand different types of breast cancer, it is still difficult to identify the most important genes and to track how the disease changes over time. This is partly because gene data are very large and complex.

This dissertation develops a computer-based framework to study breast cancer using gene expression data. The work focuses on three goals: creating realistic synthetic gene data, identifying important genes linked to cancer, and modeling how breast cancer changes from normal tissue to …

Interplay Between Phase Instability And Deformation Mechanisms In Beta Titanium Alloys In Aggressive Environments, Benjamin Elbrecht

All Dissertations

Modern designs, such as commercial jet turbines, are reliant on the high temperature performance of their constituent materials. Improvements to the strength-at-temperature of materials are critical to the continued advancement of efficiency and payload capacity in these advanced applications. This dissertation presents studies that progress towards this goal through the construction of a new experimental setup for complex temperature and force profiles that also accurately captures deformation behavior through non-contact measurements. Using this setup, studies into two specialty titanium alloys were executed: discovering the microscopic mechanisms responsible for the macroscale behavior and testing in conditions closely replicating aircraft turbine operating …

Baseline Cervical Intervertebral Disc Biomechanics And Implications For Allograft Preservation, Nathan F. Buchweitz

All Dissertations

Neck pain has become an increasingly common orthopaedic healthcare issue. Evidence shows that degeneration of cervical intervertebral discs (the cartilage between the spinal vertebrae in the neck) may be associated. While disc degeneration in the lumbar spine has been extensively studied in relation to low back pain, it has received less attention in the cervical spine. Biomechanically, the cervical (neck) and lumbar (lower back) regions of the spine differ in function. Lumbar discs resist a greater burden of body weight, whereas cervical discs are adapted for mobility to aid flexible head orientation. Despite these key differences, disc injury and degeneration …

A New Approach To Generate Combinatorial Patterns In Logical Analysis Of Data And Its Application To Predict College Retention, Salihah Ahmed E. Jaafari

Theses and Dissertations

Student retention and degree completion remain central challenges for higher-education institutions, with significant implications for student success, institutional effectiveness, and public accountability. While advances in predictive analytics have enabled earlier identification of students at risk of withdrawal, many commonly used machine learning approaches suffer from limited interpretability, constraining their practical usefulness for advising, intervention, and policy decision making. This dissertation addresses the problem of predicting student persistence by developing and evaluating optimization based, interpretable classification models within the Logical Analysis of Data (LAD) framework. Building on existing LAD formulations, this research introduces two novel pattern generation models, the Best Term …

Decomposition And Spectral Characterization Of Unsteady Loads In Pulse-Jet Propulsion Testing, Cesar Benitez

Theses and Dissertations

Pulsed jet propulsion systems produce inherently unsteady forces whose time-resolved characterization is essential for performance assessment, yet the measured load signal conflates aerodynamic forcing with the dynamic response of the measurement balance itself. This thesis develops a load centered framework for the dynamic characterization of a pulsed jet system, treating the measured load fluctuation as the primary physical observable rather than attempting full true-thrust reconstruction. A single-degree-of-freedom balance model identified through ringdown testing provides the structural reference scale, yielding a natural frequency of 8.5 Hz and damping ratio of 18%. Power spectral density, phase-averaging, and synchronous–residual decomposition is applied uniformly …

Examining The Effects Of Lateral Loading On Railroad Tapered Roller Bearings, Abel David Sanchez Trinidad

Theses and Dissertations

The loading conditions experienced by freight railcar bearings vary as a function of vehicle operating conditions. Under static conditions, bearings are primarily subjected to radial loads transmitted through the wheelset. During operation, however, track irregularities, braking events, railcar load imbalances, and curving introduce complex impact, longitudinal, and lateral forces in addition to the normal radial loading. These lateral forces increase friction within the bearing raceways, which could accelerate wear and potentially lead to premature spall initiation and propagation. While prior research at the University Transportation Center for Railway Safety (UTCRS) has demonstrated that vibration signatures can be used to detect …

Detecting Sophisticated Cyberattacks On Public Water Infrastructure, Ayrton Purdy

Graduate Theses and Dissertations (2019 - present)

In recent years there has been an increasing number of cyberattacks on public water generation and distribution systems. Advanced persistent attackers could usurp sensors and control systems to contaminate public drinking water. In order to conceal their malicious activity, they can manipulate sensor data flows to give the appearance of normal activity. The compromised sensors would report normal chemical levels even though unsafe water is entering the distribution system. In response, this research proposes a multi-sensor, cross-comparison approach to anomaly detection. The proposed approach is designed to detect sophisticated cyberattacks which are not easily detectable using traditional cyber tools. The …