Engineering Commons^™

4d Printing Of Pla And Pla-Based Composites For Load-Bearing Applications, Phaniteja Nagaraju

ETD Archive

This research investigates the deformation recovery of 3D-printed Polylactic Acid (PLA) shape memory polymers (SMPs). The study delves into the influence of Fused Deposition Modelling (FDM) parameters, such as nozzle temperature, layer thickness, and printing speed, on the thermomechanical behavior of PLA SMP honeycomb structures. The research identifies optimal printing conditions using the Taguchi approach and explores the cyclic shape memory recovery behavior of the optimized PLA SMP under compression loads.

Additionally, the research includes a chapter on the extrusion and printing of uniform-diameter polylactic acid carbon fiber (CFR-PLA) composite filaments. The synthesis of CFR-PLA involves planetary ball milling for …

Treatment Of Combined Dye And Protein Wastewater By Coagulation Process, Siriwat Tanongsak

ETD Archive

The treatment of combined dye and protein wastewater is a major environmental concern, due to its complex composition and high organic content. In this study, the effectiveness of the coagulation process for the treatment of combined dye and protein wastewater was investigated. Results of the study showed that the coagulation process was effective in removing suspended solids, color, and organic matter from the combined dye and protein wastewater. The removal efficiency varied depending on the type and dosage of the coagulant used. Among the coagulants tested, alum and ferric chloride were found to be the most effective in removing suspended …

Methods For Objective Determination Of Musculoskeletal Coordinate Systems, Tara Francesca Nagle

ETD Archive

Joint mechanics research relies on joint kinematics and kinetics measurements, represented from relative relationships of local coordinate systems (CS) belonging to bones of the joint. It’s common to define these CSs from anatomical landmarks, which are sensitive to observer variability and often don’t result in CS that best represent the functional motion of the joint. This work is presented in three articles addressing the following aims: 1) to develop a method to objectively define coordinate systems through optimization of unique passive movement paths, 2) to develop an alternative method to objectively define coordinates systems for joints with non-unique passive movement …

Influence Of Ligament Locations And Activity Profiles On Risk Of Knee Injury In Adolescents, Alexandria Mallinos

ETD Archive

The Anterior Cruciate Ligament (ACL) is the most commonly injured ligament in the body. The overall goal of this project is to develop patient-specific computational pediatric knee models that can accurately predict the in vivo biomechanical environment of the ACL. The foundation of this research is broken down into three specific parts: 1) model construction, 2) model validation, and 3) model application.

Specific Aim #1 developed anatomically accurate specimen-specific finite element representations of pediatric tibiofemoral joints. The models were able to demonstrate the ability for the Open Knee cruciate stereolithography (stl) files to be three-dimensional scaled to create subject-specific ligaments …

Capabilities Of Sintered Silver As A High Temperature Packaging Material, Bakhtiyar Mohammad Nafis

Graduate Theses and Dissertations

With electrification progressing across many sectors including industry, automotive and aerospace, the power density requirements are changing. The increased power density results in higher and higher ambient temperatures that electronics are exposed to. The response has been to move towards wide bandgap (WBG) semiconductor devices that can withstand much greater temperatures and can operate at much higher voltages than silicon. Additionally, these WBG devices deliver low drain-source on resistance (RDS_on) capabilities, enabling high current power modules that increase power density even further. This also requires the packaging to evolve in order to withstand the new requirements. As a result, researchers …

Decoding Usage And Adoption Behavior Of The Low-Carbon Transportation Market: An Ai-Driven Exploration, Vuban Chowdhury

Graduate Theses and Dissertations

The transportation sector stands as a significant contributor to greenhouse gas emissions in the United States, with its environmental impact steadily escalating over the past few decades. This has prompted government agencies to facilitate the adoption and usage of low-carbon transportation (LCT) options as alternatives to fossil-fuel-powered transportation. LCTs include modes of transportation that minimize the overall carbon footprint of the transportation sector by relying on energy sources that are environmentally sustainable. These sustainable transportation options have also garnered significant interest in the transportation research community. For government agencies and researchers alike, a comprehensive understanding of the adoption and usage …

Examining The Impact Of The Covid-19 Pandemic On Older Adults' Activity Participation And Mode Usage In A Rural State: A Case Study Of Arkansas, Arna Nishita Nithila

Graduate Theses and Dissertations

The objective of the study was to investigate the impact of the COVID-19 pandemic on the activity participation and mode usage of older adults residing in Arkansas, a predominantly rural state. Leveraging primary data collected from 1,017 older adult participants, the study employed Latent Class Analysis (LCA) to capture older adults’ heterogeneity in travel behavior and found three distinct classes: Frequent Traveler, Moderate Traveler, and Non-Traveler, based on their activity participation, mode usage during the pandemic and the pandemic’s impact on their trips. Subsequently, a Multinomial Logit Model (MNL) was employed to examine how socio-demographic attributes, residential locations, and health …

Determining The Effect Of The Presence Of Food Deserts On The Number Of Crashes In Census Tracts In Arkansas, Lizbeth Juarez-Bartolo

Graduate Theses and Dissertations

Food deserts, areas with limited access to grocery stores which sell fresh produce, dairy, and meats, are a growing concern in many communities. The presence of a food desert is known to cause great impacts on the physical health of the people residing within them, but there is little to no research on a food desert’s influence on the traffic safety of the location in which it encompasses. Based on previous studies into food deserts, studies suggest that food inaccessibility is mostly felt by rural residents. Since rural residents must travel farther distances on more hazardous rural roadways to access …

Diffusive Gradients In Thin-Films Passive Samplers For Quantitation Of Per- And Polyfluoroalkyl Substances In Water: Kinetic Modeling, Experimental Methods, And Outlook For Regulatory Monitoring, Samuel Hodges

Graduate Theses and Dissertations

Environmental sampling is the backbone of regulatory compliance in public water systems. Coupled with continuously improving analytical capabilities, grab sampling has revealed the ubiquity of emerging contaminants in water resources such as per- and polyfluoroalkyl substances (PFAS). The Environmental Protection Agency’s (EPAs) Method 533 and 537.1 specify 0.25 L grab samples undergo a solid phase extraction (SPE) to enrich PFAS up to 250-fold in 1 mL of methanol prior to analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS). This process can achieve lowest concentration minimum reporting levels (LCMRLs) between 0.53–16 ng•L−1 for the twenty-nine prioritized PFAS in drinking waters. However, toxicity …

Self-Consolidating Concrete Design For Drilled Shaft Structural Applications, Grady S. Caton

Graduate Theses and Dissertations

Self-consolidating concrete (SCC) is a relatively new concrete technology which allows the concrete to be placed without the need for manual or machine vibration. This innovation reduces labor costs, construction times, and can provide a smooth, finished surface. However, this technology is used in the United States primarily in the precast and prestressed concrete industry. The utility of SCC in structural applications, such as areas of dense reinforcement or locations where complex geometry makes consolidation impossible, is also advantageous. In this study, a series of SCC mixtures were developed both with and without fly ash replacement. These mixtures were then …

Comparing In-Situ Liquefaction Triggering Procedures For Sites In Arkansas, Sagar Barua

Graduate Theses and Dissertations

There currently exists a significant amount of uncertainty when designing piles for bridge foundations in liquefiable soil. Currently ARDOT engineers use a Standard Penetration Test (SPT) based liquefaction spreadsheet developed 10 years ago to evaluate liquefaction triggering. Since this spreadsheet was developed, updates to the liquefaction triggering procedures have been published making the spreadsheet out-of-date. Moreover, additional methods of liquefaction evaluation using cone penetration test (CPT) and shear wave velocity (Vs) provide added means of evaluating liquefaction potential. This thesis updates ARDOT's liquefaction triggering evaluation methodology with the newest procedures and incorporates additional empirical liquefaction hazard estimates such as the …

Development Of A Prototype Satellite-Tracking Telescope For Ground-Based Spectroscopy, Charles Smith

Graduate Theses and Dissertations

Spectroscopy is the practice of determining the chemical composition of a gas through analyzing the light that is filtered by the gas. Spectroscopy is commonly used by astronomers to deduce the atmospheric composition of planets. This process is done by initially measuring the spectrum of light from the star that the planet orbits, and then measuring it again once the planet is in between the observer and the star. The spectrum light that is filtered out is dependent on the chemical composition of the gas, and so this information can be used to determine the chemical composition of the atmosphere …

Developing Asphalt Mix Design Specifications Based On Apa And Ideal-Ct Testing, Jonathan Stonestreet

Graduate Theses and Dissertations

Some asphalt mixes, following the Superpave mix design procedure, have been reported to be too stiff, making cracking a prevalent form of pavement distress. Additionally, cracking has been reported to be the main form of distress of asphalt pavements in the State of Arkansas. These facts have heightened state agencies’ interest in better performing asphalt pavements, with Arkansas resolving to explore performance-based balanced mix designs (BMD), not yet explored in the state. The primary objective of this document is to present the completed study of balanced mix designs, based on the rutting and cracking potential of asphalt pavement mixtures through …

Silver Sintering Reliability And Its Enhancement For Use In High-Density Power Modules, Alicia Medina Garcia

Graduate Theses and Dissertations

This master's thesis is dedicated to enhancing the reliability of silver sinter die attachments, a pivotal component within the dynamic realm of power electronics. The study is meticulously organized into four distinct chapters, each contributing to a comprehensive understanding of silver sinter die attachment reliability and its implications for contemporary electronic packaging. In Chapter 1, an introduction is provided to the significance of silver sinter die attachment in the context of power electronics, underlining the imperatives associated with miniaturization, weight reduction, and heightened efficiency. The compelling need to investigate die attachment properties, particularly in high-temperature and high-power-density environments, is emphasized. …

2023 Fall Engr333 Section B Poster, Ally Gauss, Stuart Johnston, Zachary Rozendal, Nora Terbeek, Samantha Bush, Daniel Cordeiro, David Harris, Nathan Zylstra, Mikayla Bindon, David Schmurr, Zachary Swart, Micah Vandeburg, David Conhoff, Mitchell Cook, Yonggi Kim, Mark Schultz

ENGR 333

Poster of Section B of ENGR-333 Fall 2023.

2023 Fall Engr333 Section A Poster, Owen Kalsbeek, Panashe Makuvaro, Luke Penning, Caleb Gaffner, David Visser, Jared Skaggs, Stephen Langerak, Kyle Borror, Caleb Clark, Michael Lanning, Brayden Raches, Sam Mennega, Seth Devries, Kyle Vandusen, Hayden White

ENGR 333

Poster of Section A of ENGR-333 Fall 2023.

Learning And Control For Complex Multiagent Systems, Vrushabh S. Donge

Electrical Engineering Dissertations - Archive

Complex multiagent systems (MASs) are pervasive in various fields, from power system networks, and autonomous robotics to traffic management, where groups of agents interact to achieve collective objectives. Effective coordination and control of such systems pose significant challenges due to their inherent complexity and the need for adaptive, efficient strategies. This dissertation explores combining data-driven approaches, reinforcement learning (RL), and control theory to address these challenges. We present novel methodologies for learning and controlling complex MASs, emphasizing the development of adaptive algorithms that can autonomously adapt to dynamic environments, collaborate with other agents, and optimize system-wide performance. Our findings offer …

Process-Driven Microstructure Tailoring During Additive Manufacturing Of Ti-6al-4v, Ahmet Alptug Tanrikulu

Material Science and Engineering Dissertations - Archive

In recent years, additive manufacturing (AM) has attracted the attention of many researchers due to the technology providing opportunities in terms of improved functionality, production repeatability, efficiency, and cost and time issues. While AM techniques made possible the realization of complex geometries, their use in critical applications have faced challenges due to the anisotropic characteristic of AM-built parts. More specifically, non-equilibrium AM processes involve steep temperature gradients and rapid solidification, yielding a unique microstructure, e.g., columnar-shaped grains with preferred texture, in final AM-built products and hence anisotropic mechanical properties. Despite significant studies on improving the microstructure of AM-built parts, it …

Spatially Resolved Elastic Modulus Of Magnesium Silicate Hydrate: A Cementitious Material, Arif Syed

Material Science and Engineering Theses - Archive

Magnesium-based cements such as magnesium silicate hydrate (MSH) have drawn interest as an environmentally friendly substitute for ordinary Portland cement because of their potential for reduced carbon footprint. The precise determination of these materials' elastic moduli is important to better assess their mechanical performance. Atomic force microscopy (AFM) is an effective tool for precise and spatially resolved quantification of nanomechanical characteristics of materials, including thin films. In this study, elastic modulus maps of MSH grown on single crystal mica surfaces were obtained using amplitude modulation-frequency modulation AFM. The effects of the Mg:Si ratio and morphology on the elastic modulus of …

Design And Demonstration Of An Inertial-Stabilized Single-Axis Headlamp For Mobile Systems, Thomas Avery Allsup

Mechanical and Aerospace Engineering Dissertations - Archive

The introduction of adaptive headlamps has added left and right movement of the headlamps to enhance the vision of the driver during a turn at night. Adaptive headlamps also allow up and down motion of headlamps in either two discrete positions with low and high beams based on vehicle speed and oncoming traffic lights or using the vehicle suspension measurement to adjust headlamp beam angles in any angle between low and high. Using the vehicle suspension ignores the roadway influence on where the headlamps should be positioned to illuminate the roadway for the driver. This dissertation develops governing equations and …

On The Development Of A Sensing System Methodology To Evaluate The Viscoelastic Properties Of Soft Tissues As A Means Of Disease Prognosis, Shashank S. Kumat

Mechanical and Aerospace Engineering Dissertations - Archive

Identification of tissue viscoelastic properties could provide valuable information for assessing its healthiness or disease state. Current technologies present challenges to access and perform localized tissue assessment in confined spaces in the human body through contact indentation/palpation. As such, there is a need for a diagnostic system capable of measuring tissue relaxation response at the local site by accessing the tissue through a natural orifice. This dissertation presents a strain gauge-based uniaxial micro-force sensor, part of the aforementioned system, capable of measuring tissue response data in confined human space environments. A sensing system design methodology is developed and presented. The …

Optimizing Energy Efficiency And Performance In High-Performance Computing Through Advanced Direct-To-Chip Liquid Cooling And Labview-Based Monitoring And Analysis, Chandraprakash Ashok Hinge

Mechanical and Aerospace Engineering Dissertations - Archive

This research endeavors to significantly enhance energy efficiency and performance in the realm of high-performance computing (HPC). This goal is pursued through a synergistic approach that leverages advanced direct-to-chip liquid cooling systems and integrates LabVIEW for real-time monitoring and analysis within data centers. The primary aims of this study are manifold. First, it seeks to evaluate the effectiveness of different single-phase liquid coolants when employed in direct-to-chip cold plate cooling for HPC systems. Additionally, the research focuses on characterizing row manifolds, crucial elements in the design of efficient data centers. The study also endeavors to devise a strategic control mechanism …

Multiple Dipole Source Position And Orientation Estimation Using Non-Invasive Eeg-Like Signals, Saina Namazifard

Mechanical and Aerospace Engineering Dissertations - Archive

The human brain comprises of neurons that connect with each other via electrical signals. One can record and measure these activities using an electroencephalogram (EEG). An essential use of the EEG is in locating the generating source of these signals, usually approximated by dipoles. This is important because, in some particular circumstances, neurons may not function optimally and could make the equivalent dipole generate abnormal signals. This could be a result of seizures or other brain disorders. In order to isolate such disorders, the challenge is to find a non-invasive way to locate the anomalous source. This research aims to …

Thermo-Mechanical Analysis Of Heterogenous Integrated Packages And Immersion Cooling Of Data Center Servers, Krishna Bhavana Sivaraju

Mechanical and Aerospace Engineering Dissertations - Archive

III-V materials such as Gallium Arsenide (GaAs) and Indium Phosphide (InP) are used as substrates for opto-electronic devices like vertical cavity surface emitting lasers (VCSEL), edge emitting lasers and light emitting diodes. System in Package integration of the III-V materials to silicon requires a reliable bonding technique. Though there are several bonding techniques like direct wafer bonding like hetero-epitaxially grown islands on a silicon wafer bonding enable the bonding, flip-chip bonding is used in this study owing to its superior electrical connectivity, mechanical reliability, heat conduction capability and ease of fabrication due to self-alignment. Finite element models of four different …

Noninvasive Mapping Of Global And Regional Functional Connectivity In The Brain Of Children With Drug Resistant Epilepsy And Healthy Controls, Ludovica Corona

Bioengineering Dissertations - Archive

For patients with drug resistant epilepsy (DRE), resective surgery is the most effective treatment to achieve seizure-freedom. Its success largely depends on the resection, ablation, or disconnection of the epileptogenic zone (EZ), defined as the minimal area indispensable for the generation of seizures, with minimal or no functional deficits. To date, there is no clinical exam to delineate the EZ unambiguously. Instead, the EZ is indirectly defined through multiple noninvasive diagnostic tests used by the multidisciplinary epilepsy team, whose results are often insufficiently concordant or inconclusive. Thus, extra-operative intracranial electroencephalography (iEEG) monitoring may be needed to precisely define the EZ …

Lung Cancer Growth Forecasting And Classification Models By Machine Learning Using A Novel 2d Co-Culture High Throughput Device, Adam Adrien Germain

Bioengineering Dissertations - Archive

Co-culture devices have commonly been used during in vitro experimentation to create therapeutic testing devices for lung cancer that more closely mimic the in vivo environment to gain better insights into new therapies and the reasons for inconsistency for current therapies. Moreover, AI (artificial intelligence) in the form of convolutional neural networks (CNN) and convolutional long-short term memory neural networks (convLSTM) are being used to classify, diagnose, and predict drug outcomes from the visual data provided by clinical imaging modalities, such as CT-scans, MRIs, or histopathological slides among others, or from numerical and textual data gathered from the genetic testing …

Advances And Applications In Ultrasound-Switchable Fluorescence Imaging, Liqin Ren

Bioengineering Dissertations - Archive

Cancer diagnosis is a prerequisite for further medical therapy and treatment. Near-infrared (NIR) fluorescence imaging is a desirable modality without invasiveness and nonionizing radiation. However, fluorescence suffers from a strong light scattering in tissues, leading to a low spatial resolution and low sensitivity in centimeter-deep tissue (limited to several millimeters). To enhance spatial resolution and avoid the high scattering of conventional fluorescence imaging in deep tissue, ultrasound-switchable fluorescence (USF) imaging has emerged as a highly promising technique for biomedical imaging and research. The principle of improving spatial resolution in USF imaging is to confine the fluorescence emission from thermosensitive fluorophores …

Development Of Multiscale And Multidimensional Light Sheet Microscopy For Image-Based Modelling Of Organogenesis, Tanveer Ashwini Ashwini Teranikar

Bioengineering Dissertations - Archive

Behavioral analysis of individual cells, in the form of structural phenotypes arising in response to mechanical stimuli or genomic alterations as small molecule intermediates of disease, are instrumental for understanding organogenesis. In this regard, dynamic cell tracking or temporal changes in cell shape, area and size are vital for modelling tissue interactions. However, optical diffraction limits imposed by lenses, hinders high resolution volume reconstruction of microscale biological processes and subcellular organelles. Thereby, isotropic intensity is restricted to limited focal volumes, reducing imaging distance to less than 1 mm for high magnification. To combat this, Light Sheet Microscopes (LSM) have emerged …

Quantification Of Dynamic Changes Of Hemodynamic And Metabolic Responses To Brachial Artery Occlusion: A Broadband Near-Infrared Spectroscopy Study, Caroline Elizabeth Carter

Bioengineering Theses - Archive

Cardiovascular disease (CVD) is a leading cause of death in the United States, and non-Hispanic African Americans are at higher risk than other racial and ethnic groups. Endothelial dysfunction is a major contributor to CVD development and progression. Remote ischemic pre/conditioning (RIC), which involves exposing cells or tissues to brief sublethal stress, has been shown to protect cardiovascular cells from ischemia and reperfusion injury, including CVD. This study aimed to investigate hemodynamic and metabolic dynamics in response to 5-min forearm arterial occlusion using broadband near-infrared spectroscopy. My thesis is a tripartite investigation that weaves RIC, mitochondrial dynamics, and health disparities …

Formation And Morphological Changes Of Stress Actin Filaments In Adipose-Derived Stem Cells, Adam Priester

Bioengineering Theses - Archive

Adipose-Derived Stem Cells (ADSCs) are a sub-type of stem cell that can be collected and isolated from the adipose tissue. Adipogenesis describes the commitment and differentiation of stem cells, including ADSCs, toward the adipocyte lineage. While much research has been completed on this process in the long term (>2 weeks), morphological changes of adipogenesis during the early phase (<24 hours) are lacking in the literature and remain to be elucidated. The current study focuses on these changes in the early and later stages of adipogenesis using adipogenic differentiation factors and fluorescent imaging analyses. Quantifiable data on morphological changes during both phases can provide insight into how these changes affect later differentiation and lay the groundwork for additional research in this area. Using fluorescent image analysis, it was shown that the eccentricity of ADSCs, a measure of cellular circularity, decreases exponentially in the early phase of adipogenesis. In contrast, the cellular area appears to increase exponentially during the same early period. During the later stages of differentiation, it was shown that actin filament length decreases exponentially and the ratio of lipid to actin length increases exponentially, demonstrating that lipid accumulation outpaces actin filament shortening and increasing circularity during the later stages. These findings may be used in future studies to further define the role of actin filament-mediated morphological changes and mechanobiology during adipogenesis.