Engineering Commons^™

Series Resonant Converters With Medium Voltage Sic Mosfets For Electric Aircraft Applications, Xinyuan Du

Graduate Theses and Dissertations

To develop high-performance high- power-density MV power converters, the emerging silicon carbide (SiC) devices are more attractive than their silicon (Si) counterparts, since the fast switch frequency brought by the SiC can effectively reduce the volume and weight of the filter components and thus increase the converter power density. From the converter topology perspective, with the MV dc distribution, the single stage isolated dc/dc converter are suitable for next-generation electric aircraft system due to soft switching and high power density. In this work, comprehensive static and dynamic characterizations were conducted for the latest 6.5 kV silicon carbide (SiC) MOSFETs from …

Design Of Phase Shifter And True Time Delay Gan Mmics For High-Temperature Ku-Band Applications, Michael Lee Thompson

Graduate Theses and Dissertations

This thesis presents the design, implementation, and high-temperature characterization of Gallium Nitride (GaN) monolithic microwave integrated circuits (MMICs) developed for beamforming and phased-array systems operating in the Ku-band (12-14 GHz). Two integrated circuits were designed: a 3-bit digital phase shifter and a 3-bit true time delay (TTD), both optimized for high linearity, low insertion loss, low phase error, and stable operation at elevated temperatures up to 300°C. Developing both a phase shifter and a TTD enabled a direct comparison of their beamforming performance and the evaluation of beam squint effects over frequency, a critical factor in wideband array design. The …

Elena Asins Y Las Afueras Del Canon: Animación Computacional Y Resistencia, Maria Mar Garrido Román

GDI. Revista de investigación de Género, Diseño e Innovación

Este artículo examina las animaciones generadas por ordenador producidas por Elena Asins, analizando cómo su práctica artística moviliza el pensamiento lógico-matemático, la programación y la experimentación visual. A través de una revisión de su metodología, contexto de producción y resultados formales, el estudio explora la incorporación de procesos algorítmicos en su obra, que generan imágenes con extensión temporal y la consolidan como una figura clave en la historia del arte digital y la animación experimental en España.

La investigación se basa en el análisis de fuentes primarias y, con el objetivo de situar su producción en un marco internacional, establece …

Bone Void Filler Materials For Augmentation In Comminuted Fractures: A Comprehensive Review, S. Sina Mohammadi, Sunjeev S. Phull, B. Sonny Bal, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Comminuted fractures, characterized by multiple bone fragments, present significant challenges in orthopedic surgery. Effective treatment often requires augmentation techniques to enhance fixation stability and promote bone regeneration. This review explores the application of bone void filler materials, including autografts, allografts, polymethyl methacrylate (PMMA), and synthetic bone substitutes such as calcium phosphate ceramics and bioactive glass, in managing comminuted fractures. Autografts are the gold standard due to their superior osteogenic potential but are limited by donor site morbidity and availability. Allografts mitigate these issues but face concerns regarding immunogenicity and reduced biological activity. PMMA, widely used for structural augmentation, provides immediate …

Local Hydrodynamics And Phase Distribution In Large-Scale Trickle Bed Reactors Using Multi-Detector Γ-Ray Densitometry, Sebastián Uribe, Ahmed Jasim, Saba A. Gheni, Nora Selem, Nouhaila Filali, Tiberiu M. Leib, Sourav Sengupta, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

This study presents a new approach of using gamma ray computed tomography (CT) in a form of arc multi-detector γ-Ray Densitometry (Arc MD-GRD) Technique where it measures the line averaged holdups of the phases which are projected on the diameter of the column to obtain their diameter profiles. This technique then was used to investigate the diameter profiles of the phases' holdups in a 12-inch diameter trickle bed reactor (TBR) using sulfur hexafluoride (SF6) as the gas phase to represent to a certain extent the industrial higher density of the used gas phase due to either the type of the …

Assessing Technology Adoption In The Construction Industry, Lucas D. Gibbons

Construction Management

The construction industry is steadily integrating new technologies, yet adoption varies widely depending on company size, market sector, and internal readiness. This study examines how common technologies such as drones (UAVs), Building Information Modeling (BIM), robotics and automated equipment, laser scanning/LiDAR, AI-driven scheduling or analytics tools, and augmented or virtual reality (AR/VR) are being applied in practice, and what benefits they are delivering to construction organizations. To better understand the factors shaping adoption, a survey was administered to members of the CMAC (Construction Management Advisory Council) board representing a range of contractors and industry stakeholders. The survey assessed current technology …

Flood-Level Estimation Using Aerial Imagery, Yisen Zhang

Electrical & Computer Engineering Projects for D. Eng. Degree

Reliable flood-level estimation using aerial UAV (Unmanned aerial vehicle) imagery is essential for effective post-disaster assessment and rapid emergency response. This study utilizes a UAV-based dataset, referred to as the UVA dataset, which integrates multiple public datasets and manually labeled UAV images, together with a multi-stage vehicle-centric framework for flood-depth estimation. The UVA dataset integrates images from multiple public sources, including Unmanned Drone Water Assessment (UDWA), Unmanned Aerial Vehicle Detection and Tracking (UAVDT), Car Parking Lot (CARPK), and additional UAV-view images collected from the internet, followed by manual annotation for water depth, viewing angle, and altitude labels. In the proposed …

An Integrated Modeling Framework To Evaluate Circularity Of The Corn–Water–Ethanol–Beef Nexus, Heydi Han

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

This dissertation examines the transition from conventional linear agricultural and food bioenergy systems toward more circular, resilient, and resource-efficient configurations. Prior research indicates that spatial and temporal variability in soil, weather, animal biological responses, and management decisions strongly influences productivity, nutrient-use efficiency, and profitability. Studies have also shown that a diversified circular system can buffer these sources of variability, improving stability and adaptive capacity. Building on these insights, the central focus of this work is to develop an integrated modeling framework to evaluate circularity within the Corn-Water-Ethanol-Beef (CWEB) nexus and explore how climate variability and management choices shape system-wide performance. …

Synthesis And Study Of Stable Organic Radicals For Mri Contrast Agents And New Materials, Sabina Dhakal

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

The first part of this dissertation focuses on the design, synthesis, and characterization of a thermally robust S =1/2 phototetrazolinyl monoradical and the development of synthetic methodologies for a high-spin (S = 1) phototetrazolinyl diradical. Electrochemical studies of the phototetrazolium cation (precursor to the monoradical) revealed a remarkably narrow electrochemical band gap (Ecell ≈ 0.82 V), suggesting promising electrical conductivity. Thermal analysis of the monoradical demonstrated excellent stability, with the onset of decomposition at 232 °C. Building on the excellent thermal stability and promising properties for electrical conductivity of the monoradical, we developed two condensation-based synthetic routes that provide viable …

Rainfall-Runoff Modelling In An Indonesian Humid Tropical Area Using Satellite-Based Precipitation Products, Noordiah Helda

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

This dissertation explores three rainfall-runoff models in the humid tropical regions of Indonesia using satellite-based precipitation products (SBPPs) and develops integrated machine-learning modeling frameworks. Several ground-based observations from BMKG (Badan Meteorologi, Klimatologi, dan Geofisika (also known as the Indonesian Agency for Meteorology, Climatology, and Geophysics)) stations across Indonesia (133−165 stations) are compared and evaluated against satellite products, indicating that GPM performs well, with R-squared values ranging from 0.54 to 0.76 and correlation coefficients ranging from 0.45 to 0.69, respectively.

In the Martapura Watershed, South Kalimantan, due to a lack of observational discharge data, streamflow was generated using the FJ Mock …

Residential Hvac Installation Faults: Field Prevalence, Drivers, And Energy Impacts, Seyed Ali Rooholghodos

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

Faults in residential comfort systems can have detrimental effects on the performance of the system, reducing the energy efficiency, affecting indoor comfort, and shortening equipment lifespan. Many of the faults occur at installation. However, there has not previously been a systematic and nationally representative study to indicate the prevalence of the faults, meaning the distribution of faults by fault type and fault intensity. Understanding true fault prevalence is essential to be able to identify derivers, and to assess the incremental electricity consumption of the new installation systems.

This study presents on-site data from 341 new central cooling systems—air conditioners and …

Large-Scale Experimental Study On The Impact Of Air Cleaning & Ventilation On Indoor Air Quality And Student Illness-Related Absenteeism, Daud Nosham

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

This large-scale randomized experimental field study investigated the effect of portable air purifiers (PAPs) on classroom’s air quality and student’s illness related absenteeism. PAPs were installed in 317 classrooms from various school districts located in Eastern Nebraska. The classrooms were randomly assigned into four conditions: three treatment conditions (T1, T2 & T3) and one control condition (device without any filter). T1 was equipped with HEPA filters, T2 added Activated Carbon (AC) layer to HEPA, and T3 further integrated Germicidal Ultraviolet (GUV) alongside HEPA and AC filters. The measured variables were carbon dioxide (CO2), fine particles (PN2.5) and coarse particles (PNcoarse), …

Experimental Characterization Of An Additively Manufactured Porous Gyroid Air-Cooled Heat Sink, Grant S. Resler

Mechanical Engineering Undergraduate Honors Theses

This paper presents the development of a ducted test facility designed to evaluate heat sinks efficiency at varying air velocities. This enables the evaluation of both heat transfer and pressure drop performance. These metrics are essential to the overall efficiency of heat sinks and help identify the optimal air velocity to achieve the desired thermal performance. A standard plate fin heat sink was used as a control for comparison to a novel heat sink. The specialized heat sink geometry was generated using nTop, a generative design software focused on additive manufacturing. This design was fabricated via Direct Metal Laser Sintering …

Solar Powered Conservation: The Effects Of Solar Photovoltaic Facilities On Avian Community Composition, Michael Christopher Ferrara

Graduate Theses and Dissertations

The expansion of solar photovoltaic energy infrastructure is transforming landscapes worldwide. Increasingly, facilities are planted with native vegetation, yet how vegetation characteristics and landscape variables shape wildlife communities in solar facilities remains poorly understood. Because avian populations have been in decline and are sensitive to habitat changes, understanding how solar facilities influence avian communities is important. In Chapter 1, we used autonomous recording units, local vegetation measurements, and land use and land cover data to quantify how avian community occupancy is influenced by solar cover in solar facilities and comparable reference sites. We used a Bayesian multi-species occupancy model to …

A Study On Utilizing Coherently Coupled Orbital Angular Momentum Beams For Maritime Sensing And Communication, Evan Robertson

All Dissertations

A large portion of the world is covered in water which introduces a couple of key challenges in communication and sensing systems. The impact of particulates in the water will limit the ability to successfully transmit information through the water. The study of how the channel impacts specific frequencies and the ability to transmit more information at a single time can limit the impact of this environment in how it degrades an optical communication system. In sensing applications, it is important to detect information related to an object’s motion which will either be towards or away from a system, or …

Coupling Material Formulation Strategies To Tailor Piezoelectric Properties Of Ceramic Lattices, Amanda Lauren Borgaro

Open Access Theses & Dissertations

This thesis examines the material formulation and infiltration processes required to create interpenetrating ceramic composites with a particular focus on developing piezoelectric ceramic-epoxy lattice structures (PCELS). Following this, a high–solid loading barium titanite photopolymer resin (BT40) was developed to produce BTO scaffolds with controlled porosity suitable for metal infusion. The resin’s shear-thinning behavior and scattering-dominated curing response enabled the formation of stable, uniform ceramic structures whose pore networks directly influence infiltration behavior. Building on this foundation, a low-temperature Field’s Metal (FM) infiltration method was established using controlled thermal equilibration and the melting of pre-formed alloy rods. By maintaining the ceramic …

Computational Methods For Complex Electromagnetic Geometries And Media, Edgar Bustamante

Open Access Theses & Dissertations

Additive manufacturing has enabled electromagnetic devices with increasingly complex geometries, but existing numerical tools remain limited in their ability to model and design such structures. This dissertation presents two major advancements that address these restrictions in the finite-difference frequency-domain method (FDFD) and the spatially-variant lattice algorithm (SVLA). These two numerical methods provide a foundation for future exploration in the simulation, optimization, and realization of next-generation electromagnetic devices. First, a general bianisotropic FDFD formulation based on the vector wave equation is presented that enables practical modeling of metamaterials using effective medium homogenized parameters rather than explicitly resolving subwavelength metamaterial features. The …

Development Of Oxide And Oxynitride Thin Films For Advanced Optical Applications, Nathan Christopher Episcopo

Open Access Theses & Dissertations

To develop Ga2O3 and TiOₓNᵧ thin films for optical applications, the process–structure–properties relationship was investigated using a comprehensive set of characterization techniques to establish the atomic structure and composition of the films in relation to the deposition conditions. The results provide critical insights into how deposition parameters influence the atomic structure and composition during magnetron sputtering. Furthermore, the correlation between atomic structure and composition with the optical and electrical properties of the films was examined to determine how variations in these factors affect functional performance. Collectively, these findings offer the necessary information to target desirable optical properties for Ga2O3 and …

Triply Periodic Minimal Surface Design And Resin Engineering For Hybrid Piezoelectric Ceramic Composites, Joshua Zahn Renaldo Dantzler

Open Access Theses & Dissertations

Chapter I:This chapter investigates Barium Titanate (BTO)-epoxy composites reinforced with 3D-printed zirconia triply periodic minimal surface (TPMS) scaffolds. Gyroid and Primitive lattices fabricated by digital light processing (DLP) were compared with a bulk composite. The Primitive architecture showed the greatest improvement, with an elastic modulus ~ 20% higher than the Gyroid and ~ 5% higher than the bulk. Normalized piezoelectric coefficients increased substantially, with d33 enhanced by ~ 2750% and g33 enhanced by ~ 120% relative to the bulk. Under cyclic loading, the Primitive lattice generated specific voltages ~ 575% greater than the bulk and ~ 60% greater than the …

Design And Validation Of Model Predictive Controllers For Lateral Vehicle Control, Keren Flores

Open Access Theses & Dissertations

This thesis develops, implements, and evaluates a Model Predictive Control (MPC) framework for lateral vehicle guidance using a linearized bicycle model. The complete control architecture is formulated from first principles, beginning with the derivation of the continuous-time planar dynamics and their conversion into a discrete-time state-space representation suitable for real-time control. The MPC problem is constructed explicitly through the development of prediction models, output selection matrices, and quadratic cost formulations. The controller is evaluated through a Python simulation environment that includes reference trajectory generation, nonlinear vehicle propagation, and constraint handling. Robustness is examined using systematic perturbations to vehicle mass, tire …

Mbse For Process Analytical Technology- Bwon Analysis Case Study, Arnaldo Garcia Cervantes

Open Access Theses & Dissertations

Volatile Organic Compound (VOC) emissions from industrial sources, particularly Benzene, present significant environmental and public health challenges. Regulatory frameworks, such as the U.S. Environmental Protection Agency’s Benzene Waste Operations NESHAP (BWON), mandate strict monitoring of control devices, specifically carbon adsorption canisters, to prevent emission breakthrough. However, current industry practices rely heavily on manual Method 21 testing, a labor-intensive process that creates lagging indicators and increases the risk of non-compliance events. This thesis proposes the design and development of an on-line, automated fugitive emissions monitoring system tailored for carbon canisters using Model-Based Systems Engineering (MBSE). Utilizing the Object-Oriented System Engineering Method …

Microstructure Evolution During Annealing Of Cryogenically Processed Cantor High Entropy Alloy, Mynel Gomez

Open Access Theses & Dissertations

This work focuses on the annealing behavior of a cryogenically processed Cantor high entropy alloy over a wide temperature range of 500–800°C. Scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were employed to analyze the microstructural evolution, with particular emphasis on twinning. Hardness and grain size were measured to correlate these microstructural changes with mechanical properties. The cryogenically processed alloy exhibited a high density of twin bundles, resulting in an initial hardness of 338 HV. Upon annealing at 500 °C, 550 °C, and 600 °C, the material showed only a limited degree …

3d Face Modeling From 2d Images Using Deep Neural Networks, Mario Alberto De La Cruz Armendariz

Open Access Theses & Dissertations

Applications of 3D face reconstruction include biometric authentication, personalized avatars and digital identity, medical visualization, forensic analysis, and broader human-computer interaction. We propose an approach to 3D face reconstruction that can generate a fully textured 3D facial model using only two grayscale images: a front view and a profile view of the subject. Once trained, the system can perform the reconstruction autonomously without manual intervention. Unlike traditional methods requiring multi-camera setups, depth sensors, or cloud-based processing, the proposed approach runs fully offline on a standard CPU, supporting dynamic execution across CPU cores and eliminating the need for a dedicated GPU. …

Development And Application Of Deep-Level Spectroscopy Systems For Characterizing Irradiation-Induced Traps In Gallium Nitride Schottky Diodes, Donald Hodgson

Open Access Theses & Dissertations

Crystal defects are a natural consequence of the gallium nitride (GaN) crystal growth process and may also be introduced by exposure to radiation environments, leading to degradation of device performance. Detection of these defects are completed through various methods of characterization including Deep-Level Transient Spectroscopy (DLTS) and Deep-Level Optical Spectroscopy (DLOS). In this work, a custom DLOS measurement system was developed and validated to investigate deep-level defects in GaN Schottky diodes before and after irradiation. GaN Schottky diode structures and wafer layouts were designed based on baseline technology provided by the University of New Mexico (UNM) and modified to meet …

Calibration Of Low-Cost Pm2.5 Sensors Using Data Continuously Generated At A Reference Station In El Paso, Texas, Brenda Lizbeth Hernandez

Open Access Theses & Dissertations

Low-cost sensors (LCS) offer a cost-effective way to expand air-quality monitoring networks, but they require strong calibration methods to ensure reliable performance under changing environmental conditions. In this study, Clarity LCSs were co-located with a state reference monitor for 6 months to evaluate fixed-time (2-, 3-, 4-, and 6-week) and rolling (2- and 3-week) calibration approaches. A multivariate regression model using PM1, PM2.5, PM10, and relative humidity was used to generate calibration coefficients for a “base sensor.” Data from two additional sensors were normalized to the base unit using linear regression, and their calibration coefficients were applied across the network. …

Efficient Adaptive Spline-Based Path Planning For In-Space Servicing, Assembly, And Manufacturing Applications, Christian Lozoya

Open Access Theses & Dissertations

Autonomous robotic systems operating in cluttered and partially observed environments require trajectory generation methods that produce smooth and dynamically feasible motion while reacting to locally sensed obstacles. This requirement is especially pronounced for free-flyer and in-space servicing, assembly, and manufacturing (ISAM) platforms, where onboard sensing is sparse, global environmental information is unavailable, and communication or computational resources are constrained. In such settings, motion plans must be updated online using incomplete and rapidly changing local observations, while avoiding excessive replanning that can lead to oscillatory or unstable behavior. Many existing approaches either rely on dense optimization over extended horizons, which is …

Investigation Of Hot Mix Asphalt Aging Effect On Binder Performance, Zahra Mohajeri

Open Access Theses & Dissertations

Asphalt roads continuously experience physicochemical changes under the combined influence of oxygen, heat, ultraviolet (UV) radiation, and water. Oxidation increases molecular polarity and association, causes maltenes loss, and continues hardening the asphalt binder, reducing ductility, stress-relaxation capacity, and resistance to cracking (Petersen 1982; Colbert and You 2012). Because aging is a cumulative process beginning at plant production, accelerating during construction/compacting, and continuing in service, the laboratory tests and indices must capture the extent of short-and long-term aging to support performance-related specification and Balanced Mix Design (BMD) (AASHTO R30 2022; Kim et al. 2017). This chapter reviews: (i) laboratory and field-representative …

Further Insights Into The Network Link Outlier Factor's (Nlof) Light-Load Penalty, Sunday Oluwaleke Ogundele

Open Access Theses & Dissertations

This research investigates the performance of the Network Link Outlier Factor with Most Likely Links (NLOF:MLL), under varying network load conditions. Earlier studies reported that the NLOF:MLL algorithm experienced a noticeable drop in fault-localization accuracy when operating in lightly loaded networks. To further examine this limitation, 240 experiments were carried out to observe how the algorithm responds as overall network load increases. The evaluation focused on the classification performance metrics: precision, recall, and F1-score. The results show that NLOF:MLL’s effectiveness improves as network load increases but that the rate of improvement slows progressively, eventually stabilizing in a pattern consistent with …

Evaluating Large Language Models For Requirements Engineering And Verification: A Comparative Analysis Of Gpt-5 And Gemini 3 Pro, Guadalupe Nevarez

Open Access Theses & Dissertations

Large Language Models (LLMs) are increasingly viewed as viable tools for Systems Engineering, yet empirical data regarding their effectiveness in generating engineering-quality requirements remains limited. This thesis compares the performance of GPT-5 and Gemini 3 Pro in generating system functional requirements for the Miner Guardian Drone, a prototype UAV designed for minefield remediation. Both models were provided with identical prompts and tasked with producing 15 functional requirements. Two independent raters evaluated the outputs using a nine-dimensional quality rubric aligned with IEEE 29148 and INCOSE guidelines to ensure rigorous assessment. The difference between the models was analyzed using descriptive statistics and …

Decoupling Piezoelectric And Pyroelectric Effects In Anisotropic Polymer-Ceramic Lattices Produced Via Fused Filament Fabrication, Sofia Alexandra Perez

Open Access Theses & Dissertations

This thesis investigates how multi-material fused filament fabrication (FFF) can be used to engineer lattice structures that decouple piezoelectric and pyroelectric responses within a single polymer–ceramic composite. A hybrid ABS–BaTiO3/PLA lattice—referred to as the Hybrid PIZCAL—was designed to direct mechanical strain along the Z-axis while suppressing deformation in the transverse directions. After thermal poling, the lattice exhibited a 293% increase in Z-axis voltage sensitivity compared to a monolithic ABS–BaTiO3 cube and significantly reduced off-axis electromechanical output. Finite element simulations and directional compression testing confirmed that geometric anisotropy and material zoning produce strong, axis-selective piezoelectric behavior. The second part of this …