Engineering Commons^™

Laser Surface Processing For Enhanced Adhesion Between Diamond Coatings And Metallic Substrates, Zhipeng Wu

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

Application of diamond coatings on metallic substrates endows them with superior properties including mechanical robustness and corrosion resistance, rendering them highly adaptable for diverse industrial and technological applications. However, significant disparities in coefficients of thermal expansion (CTEs) result in pronounced residual stress near interfaces, causing delamination of the diamond coatings. Moreover, weak chemical bonding poses a concern for certain metallic substrates. Laser surface processing techniques show promise in enhancing adhesion by altering stress distribution and improving mechanical bonding. Therefore, the research efforts described in this dissertation mainly focus on femtosecond (fs) laser texturing for enhanced adhesion of diamond coatings on …

Applying Circuit Theory To Describe Changes In Structural Landscape Connectivity In Response To Wildfire, Christian Ross Nielsen

School of Natural Resources: Dissertations, Theses, and Student Research

Understanding and conserving ecological connectivity is critical to the preservation of vulnerable landscapes. Circuit theory, in which landscapes are imagined as circuit boards with varying resistances to the flow of current, is being increasingly used to model spatially explicit connectivity of landscapes and to inform land management and conservation decision-making. Utilizing continuous, quantitative estimates of percent cover by five land cover functional groups to create a conductance surface, this study expanded upon an established application of circuit theory that used the open-source software Circuitscape to model species-agnostic, omnidirectional connectivity. This model was automated using Python to create time-series connectivity maps …

Integration Of Matlab And Machine Learning To Accelerate Evaluation Of Biological Activity In Agricultural Soils And Promote Soil Health Improvement Goals, Andrew Stiven Ortiz Balsero

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Traditionally, assessments of soil biological activity have been confined to laboratory settings, creating a disconnect with practical in-field methods. To bridge this gap, cotton fabric degradation has been used to illustrate soil microbial activity under different management practices. While effective, these demonstrations are subjective and labor-intensive.

Researchers have explored using image processing software like ImageJ and Adobe Photoshop to streamline this process. Although these tools accurately quantified fabric degradation under varying soil conditions, the methods remained labor-intensive and complex. Consequently, these methods were still not ideal for on-farm use by agricultural practitioners.

To further address labor and complexity limitations, the …

Advancing Prediction And Decision Analytics Techniques To Improve Treatment Of Tuberculosis, Maryam Kheirandish Borujeni

Graduate Theses and Dissertations

Tuberculosis (TB) remains a global health challenge, significantly impacting morbidity and mortality rates worldwide. Despite advancements in diagnosis and treatment, TB continues to pose substantial challenges, particularly in low-resource settings. This dissertation aims to develop a robust treatment monitoring framework for TB patients to ensure personalized and effective treatment using demographic and clinical information. The current standard TB treatment framework, recommended by the World Health Organization (WHO), involves monitoring patients through laboratory tests such as smear and culture sputum tests at specific time points during treatment. These tests, however, are not fast and accurate enough to determine the severity of …

Resolving The Size And Charge Of Small Particles: A Predictive Model Of Nanopore Mechanics, Samuel Bearden, Tigran M. Abramyan, Dmitry Gil, Jessica Johnson, Anton Murashko, Sergei Makaev, David Mai, Alexander Baranchikov, Vladimir Ivanov, Vladimir Reukov, Guigen Zhang

Chemical and Materials Engineering Faculty Publications

The movement of small particles and molecules through nanopore membranes is widespread and has far-reaching implications. Consequently, the development of mathematical models is essential for understanding these processes on a micro level, leading to deeper insights. In this endeavor, we suggested a model based on a set of empirical equations to predict the transport of substances through a solid-state nanopore and the associated signals generated during their translocation. This model establishes analytical relationships between the ionic current and electrical double-layer potential observed during analyte translocation and their size, charge, and mobility in an electrolyte solution. This framework allows for rapid …

Comparative Study Of Hydrogen Embrittlement On Ebm Inconel 718 As-Built And Hiped Specimens, Julio Cesar Diaz

Open Access Theses & Dissertations

This study investigates the effects of hydrogen embrittlement (HE) on Inconel 718 parts produced using Electron Beam Melting (EBM) with a spot melting scanning strategy, focusing on analyzing the material's microstructure and mechanical properties. This research aims to understand the impact of hydrogen charging on both as-built and Hot Isostatically Pressed (HIPed) samples of Inconel 718, a material widely used in high-stress applications in aerospace and energy industries.The methodology included detailed characterization using techniques such as Electron Backscatter Diffraction (EBSD), Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM) followed by hydrogen charging of EBM-fabricated Inconel 718 samples. Mechanical testing, …

Development Of 3d Human Cardiovascular And Cancer Tissue Model Within A Self-Driven Microfluidic Platform For Preclinical Drug Screening, Aibhlin Alexis Esparza

Open Access Theses & Dissertations

According to the American Heart Association and World Health Organization, cardiovascular diseases (CVDs) are the leading cause of death worldwide. Monolayer cell culture (2D) and animal models are conventional methods to study CVDs, however, they limit researcherâ??s ability to simulate the human cardiovascular cellular microenvironments and accurate predication of pharmaceutical drug responses. Human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs), biomaterials, and microfluidic technologies can be combined to create a controlled, reproducible 3D platform to study physiologically-relevant cellular responses to biochemical and physical changes in the microenvironment. My dissertation work demonstrates the development of novel self-driven microfluidic devices designed with …

Using Causal Inference To Understand Public Perception Towards Electric Vehicle Adoption, Jesus Alejandro Gutierrez Araiza

Open Access Theses & Dissertations

Why despite all efforts to promote Electric Vehicles (EVs) as an alternative transportation method through strategies such as tax credits on unit purchasing or long-term environmental benefits communication, its market penetration has not reached the expected goals in the United States? Even though there have been important advancements in the EV technical perspective and financial EV purchasing incentives, the final EV customers still face barriers on their scenarios that do not allow them to purchase this type of contemporary transportation means. Not understanding their local barriers could be a mistake that could reduce EVA expectations in the country and keep, …

Flow-Shop Scheduling Optimization Through Discrete-Event Simulation And Neural Networks., Jesus Ricardo Herrera Garfio

Open Access Theses & Dissertations

Industrial developments over the past few decades have transformed manufacturingprocesses, emphasizing the necessity for efficient scheduling systems. The shift from manual scheduling to automated and optimized systems has underscored the need for innovative approaches to improve production efficiency. Scheduling optimization of manufacturing systems is critical to improve operational efficiency. Typically, these scheduling problems become challenging because they involve coordinating various production tasks, resource management, and makespan minimization. These challenges are particularly evident in flow-shop manufacturing systems, where the operation sequencing significantly impacts overall performance. The main objective of this manuscript is to present the methodology followed to optimize the schedule …

Integrating Machine Learning And Simulation For Resource Planning Of Hospital Systems Based On Predicted Length Of Stay, S M Atikur Rahman

Open Access Theses & Dissertations

Recently Hospital Systems faced a high invasion of patients generated by several events such as health crisis related epidemic (COVID, FLU) or seasonal flows. Hence, managing hospital bed availability and efficiency with proper care is obligatory for addressing the challenges associated with the overburden of patients. However, the Length of stay (LOS) is often increased due to the high patient influx and overcrowding problem occurs within the Hospital. It resolves these issues, it is essential for hospital authority to predict the Patients LOS which is the crucial indicator for the use of medical resources (allocation, utilization of providers and resource) …

Design Considerations For Self-Deploying Origami-Inspired Space Arrays, Kathryn Faith Varela

Theses and Dissertations

Origami engineering involves many steps, including selecting a pattern, accommodating for thickness, and choosing stabilization, damping, and deployment methods, the last of which is particularly important if the array is intended to self-deploy. Through metrics and case studies, this research strives to aid designers in creating origami-inspired deployable arrays. The approaches vary as each chapter focuses on a different aspect of origami engineering. By introducing a thickness accommodation technique and reducing complications with rigid-foldability (when applicable), this work shows how the geometrical structure can be modified to help the array stow and deploy. By providing quantitative and qualitative metrics for …

A Study Of Commuting Conditions For Construction Professionals In The San Francisco Bay Area, Ethan John Argue

Construction Management

This paper investigates the commuting experiences of workers in the San Francisco Bay Area, with a focus on construction industry professionals. Numerous scientific studies and reports have been done regarding both traffic congestion in the Bay Area and commuting conditions for construction workers. By comparing points of information on Bay Area workers like their job type, commute length and commute satisfaction, this study aims to uncover correlations and understand who is affected the most by traffic congestion. After extensive surveys and interviews of Bay Area workers, average commute times were calculated and reported for several industry subsets, along with averages …

Performance And Enhanced Efficiency Induced By Cold Plasma On Sapo-34 Membranes For Co2 And Ch4 Mixtures, Fnu Gorky, Vashanti Storr, Grace Jones, Apolo Nambo, Jacek B. Jasinski, Maria L. Carreon

Chemical Engineering Faculty Publications and Presentations

In this study, we investigate the influence of cold-plasma-induced enhanced performance and efficiency of SAPO-34 membranes in the separation of CO₂ and CH₄ mixtures. Placing the herein presented research in a broader context, we aim to address the question of whether cold plasma can significantly impact the membrane performance. We subjected SAPO-34 membranes to plasma mild disturbances and analyzed their performance in separating CO₂ and CH₄. Our findings reveal a notable enhancement in membrane efficiency and sustained performance when exposed to cold plasma. The pulsed plasma separation displayed improved structural integrity, and the experimental results …

Analysis Of The Relationship Between Flow Patterns In The Post-Stenotic Region Of Model Arteries And Stenosis Severity., Michael Laroche

Electronic Theses and Dissertations

In this study, contour fields of mean age and turbulence kinetic energy (TKE) in the post-stenotic region of model arteries were analyzed to explore their correlation with FFR. While both high and low FFR cases exhibited similarities with an inner low-age region and an outer high-age region, low FFR cases displayed asymmetry in their low-age regions due to eccentric stenosis. Moreover, gradients of age across the artery diameter were more pronounced for low FFR cases. Additionally, low FFR cases demonstrated significantly higher TKE in the post-stenotic blood jet stream compared to high FFR cases that are reflected in low-age boundary …

Carboxen Micropreconcentrator Performance For Analyzing Btex In Air., Raymond Daniel Spargo

Electronic Theses and Dissertations

Volatile Organic Compounds (VOCs) are a class of toxic chemicals in environmental air associated with several serious health risks. Some of the most common and concerning VOCs are Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX). To maintain healthy air quality in these environments, researchers pursue instruments and processes to quickly and accurately predict sub-ppb concentrations of BTEX in indoor and outdoor air. By employing a micropreconcentrator (μPC) to combine Solid-Phase Micro-Extraction (SPME) with Gas Chromatography Mass Spectrometry (GC-MS) analysis, trace BTEX content in air samples can be captured, extracted and analyzed. In this thesis, a dual-compartment μPC with Carboxen 1000 …

The Impact Of Internal Curing Additives On Compressive Strength, Shrinkage, And Internal Relative Humidity Of Mortars., Payton Scott

Electronic Theses and Dissertations

Curing is a critical step in concrete construction. When a concrete specimen is properly cured, its shrinkage and early age curling/warping can be reduced, and the concrete strength can be increased. Curing methods can be divided into two categories: traditional external curing and emerging internal curing methods. Internal curing has similar benefits to external curing, such as reduced early-age cracking and shrinkage risk, and increased durability and strength. The purpose of this research is to investigate internal curing additives and their impact on length change, weight change, compressive strength, autogenous shrinkage, and internal relative humidity. Mortar mixtures with lightweight aggregate …

A Thermo-Mechanical Analysis Of The Well-Structure Integrity In Enhanced Geothermal Systems Using Numerical Simulation, John Alfred Ganal Acevedo

Theses and Dissertations

This thesis will investigate the well structure integrity of enhanced geothermal systems. Enhanced geothermal system is a type of renewable energy generation that utilizes heat from a rock reservoir deep within the Earth’s subsurface delivered by circulating working fluids through kilometers-long well structures. However, due to the surrounding environment and harsh operating conditions, the well structures are vulnerable to deterioration and cracking, which can lead to structural failure of wells and reduced energy efficiency. The study seeks to gain a better understanding of the vulnerability of the well structure. A finite element model of a well structure was developed, and …

The Development And Analysis Of Practical Decision Support Tool Implementations: Case Studies From Small Business To Large Government Enterprise, Alexis Andaverde

Theses and Dissertations

This thesis demonstrates the critical role of decision support tools (DSTs) in both small business and large government operations, enhancing decision-making, operational efficiency, and economic benefits. By implementing Excel-based systems for small businesses and discrete event modelling for large enterprises, this research highlights the importance of adaptable and scalable solutions across various sectors. According to the U.S. Small Business Association, small businesses with 500 or fewer employees make up 99.9% of all U.S. businesses. However, 65% of new businesses fail within the first ten years, according to the Bureau of Labor Statistics. This case study focuses on the used vehicle …

Validation, Optimization, And Experimentation Of Electro-Centrifugal Spinning, Carlos Alberto Delgado

Theses and Dissertations

The aim of this study is to understand the behavior of polymeric solutions, when exposed to both electric fields and centrifugal forces through the electro-centrifugal fiber creation method, observing both effects of various parameter variations on the resulting nanofibers. The elemental deposition on electrospun fibers through in-situ processes is studied and optimized. The morphology, crystallinity, thermal properties, and elemental composition of the nanofibers were characterized. The purpose of these nanofibers is for future applications such as energy harvesting, filtration, and biomedical applications.

Advancements In Aerial Vehicle Platforms: A Guide For Design, Validation, And Implementation Of 3d Printed Drones, Alan Salvador Urteaga

Theses and Dissertations

Additive manufacturing methods have revolutionized the way products are designed and developed through a product's entire design life cycle. This is in part correlated with the nature of additive manufacturing methods that differentiate them from traditional methods. Some of the benefits of additive manufacturing methods include customizability, rapid prototyping, the production of complex design geometry, and embedded assembly manufacturing. Unmanned aerial vehicles have been on the rise for various military, commercial, or personal applications. The focus of this study is to provide detailed instructions on how to engineer a viable drone design that is impact-resistant, modular, and customizable. This study …

Development Of The Structure And Control System Of A Stewart Platform Robot For Human Balance Recovery Interventions, Rhobenn R. Alvarez Zambrano

Theses and Dissertations

In this thesis, the process to design a Stewart platform parallel robot for balance recovery with given assembly constraints and mobility requirements is described. A Model Based Design (MBD) approach in MATLAB was used as a tool to model and optimize the design of the platform through quick and repeatable workspace and movements simulations. An algorithm based on Inverse Kinematics was used to find the most adequate Stewart platform configuration which yields a workspace that fulfills the design goals best. Solidworks was used as a 3D CAD Modeling tool to elaborate machining blueprints while ensuring that each piece fits accurately …

In Situ Shear Exfoliation Of Layered Materials And Fabrication Of Multifunctional Composites, Md Abdur Rahman Bin Abdus Salam

Theses and Dissertations

To harness the extraordinary properties of 2D nanomaterials across a range of applications, including but not limited to device fabrication (such as sensors and transistors), energy storage and conversion systems (like batteries and solar cells), as well as biomedical applications (such as drug delivery and tissue engineering), it is imperative to achieve proper synthesis to single-layer form from bulk material, ensuring defect-free synthesis. Recognizing the criticality of defect-free synthesis and high yield for nanocomposite production, our focus centered on developing a facile, contamination-free, single-step, in situ shear exfoliation process for bulk materials (such as graphene, hBN, coal) within elastomers, which …

Feature Extraction From Vibration Signature Acquired From Railroad Bearing Onboard Condition Monitoring Sensor Modules, Kevin Quaye

Theses and Dissertations

The University Transportation Center for Railway Safety (UTCRS) has designed an onboard monitoring system that tracks vibration waveforms over time, to obtain a direct and more accurate indicator of bearing health. The data collected by these sensors is used for vibrational analyses of the bearings. The speed of the bearing is a fundamental parameter needed to carry out the analysis. GPS data can be used to determine bearing speed if available; however, due to size, cost and power constraints GPS is typically not available at the sensor location. This means that analysis must be delayed until the data is uploaded …

Bridging Human Emotion And Autonomous Vehicle Control: Reinforcement Learning Enhancements In The Carla Simulator, Timothy Marion Jude Lyons

Theses and Dissertations

Autonomous vehicles are a key component for an evolution in transportation as they may lead to increased safety and productivity. As autonomous vehicles advance industries will look to further increase customer satisfaction through personalized experiences for autonomous vehicle passengers. Reinforcement learning may be the key to success for autonomous vehicles. The development of autonomous vehicles, utilizing reinforcement learning, which consider the emotions of the passenger, will be a breakthrough for the automotive industry. This thesis presents a unique approach to autonomous vehicles developed with reinforcement learning which consider the human emotions of the passenger. It is a stepping stone to …

Attachment Of 2d Nanomaterials Onto 1d Nanofibers For Separation And Sensing Applications, Elmmer A. Vera Alvarado

Theses and Dissertations

Advancing materials for water desalination and sensing is essential for tackling global issues related to clean water and efficient energy systems. This thesis explores the application of 2D nanomaterials, specifically graphene, integrated onto 1D poly(vinylidene fluoride) (PVDF) nanofibers to enhance their effectiveness in these areas. Utilizing innovative techniques such as Forcespinning® and plasma treatment, PVDF nanofibers were strengthened with graphene and conductive polymers like poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS). The research involved thorough assessments using direct contact membrane distillation (DCMD) systems, oil-water separation tests, and various mechanical and electromechanical evaluations. Heat-pressed membranes consistently delivered a flux of 0.33 kg/m²/hr and …

Crowdstrike Cyber Incident Vs. Past Major Cyber Incidents: Analysis And Solutions, Priyant Banerjee

Himalayan Research Papers Archive

On July 19, 2024, a technical malfunction in CrowdStrike’s Falcon sensor software led to a global ITdisruption, affecting millions of devices across multiple sectors. This incident, although not a direct cyber-attack, caused significant operational upheavals reminiscent of major past cyber incidents. This paperexplores the CrowdStrike incident in detail, compares it with previous major cyber events, and proposescomprehensive solutions to mitigate such risks in the future.The faulty update from CrowdStrike resulted in widespread system crashes, notably the "Blue Screen ofDeath," paralyzing operations in critical sectors such as healthcare, finance, and transportation. The paperexamines the immediate and cascading effects of the incident, …

Future-Ready Digitalized Education: Unraveling The Dynamics Of Sustainable And Ethical Digital Transformation, Vaishnavi Rode

Electronic Theses, Projects, and Dissertations

Amid the brisk advancement of digital technologies, higher educational institutions and universities are finding themselves at a crucial turning point, with significant obstacles and new prospects in the realm of digital transformation. This culminating experience project delves deeply into the compounded terrain of digital transformation in higher education, emphasizing the need for sustainable practices in the face of rapidly evolving technical advancements. The research questions are: (Q1) What strategies can universities adopt to foster digital literacy among students and faculty while promoting sustainability values within their digital education programs and Why? (Q2) What ethical considerations, concerning data privacy and digital …

Classification Model For Discovering The Type Of Crop To Plant Using Ensemble Techniques, Uma Mahesh Addanki

Electronic Theses, Projects, and Dissertations

Farming plays a role in ensuring survival, especially with the growing need for increased agricultural output. It is vital for farmers to efficiently choose the crops to cultivate. By using crop recommendation systems farmers can make decisions on what crops to plant leading to yields and improved resource management. The success of crop production depends on maintaining the balance of soil nutrients and favorable weather conditions. In this research project, we created a crop recommendation system utilizing learning methods to predict the appropriate crops based on essential soil nutrients and weather patterns. We worked with a dataset sourced from Kaggle, …

Task Management Application, Dhaval Chaturbhai Hirpara

Electronic Theses, Projects, and Dissertations

The Task Management Application is a web-based platform designed to facilitate efficient task and project management, similar to other Project Management Tools like Jira, Trello, ClickUp, Wrike, Zoho Projects, and Asana. The application features three distinct roles: Administrator, Project Manager, and Employee, each with specific functionalities and permissions to streamline workflow.

Administrator: This role encompasses comprehensive project oversight, including adding, viewing, and managing project managers, supervising ongoing projects, and viewing employee details.

Project Manager: Project Managers can manage employees, assign tasks, and oversee project progress effortlessly.

Employee: Employees have dedicated functionalities to view and manage tasks assigned …

Understanding The Challenges To Robotic-Assisted Surgery Adoption From The Perspectives Of The Human-Robot Interaction, Built Environment, And Training, Patrick A. Fuller

All Theses

Introduction: Robotic-assisted surgery (RAS) is a form of minimally invasive surgery that is increasing in both its adoption and development due to many perceived advantages such as tremor reduction and motion scaling. However, RAS is still relatively new and there are a variety of novel barriers and challenges to the adoption of these platforms. Objectives: This study aims to understand how the integration of RAS platforms impacts the interactions and outcomes of interactions between surgical team members to explore the barriers from three aspects critical to facilitating Robotic-assisted-surgery (RAS) adoption: the human-robotic interaction, built environment, and RAS training. Future …