Engineering Commons^™

Experimental And Numerical Investigation Of Air-Cooled Heat Sinks, Ethan Weems

Mechanical Engineering Undergraduate Honors Theses

Lightweight and affordable cooling capabilities are critical as the physical scale of electronics continues to decrease. Air-cooled heat sinks that dissipate heat from electronic components to the surrounding air are excellent candidates to fill this role. While plate-fin and pin-fin heat sinks have been implemented extensively for electronic cooling, recent advances in additive manufacturing enable the fabrication of more complex structures. In this undergraduate Honors thesis, a means by which to generate novel heat sink geometries is presented. To that end, an experimental characterization facility is developed to evaluate existing traditional heat sinks. The heat transfer performance of the heat …

A Review And Analysis Of General Aviation Instructional Accidents, Sydney Sommers

Mechanical Engineering Undergraduate Honors Theses

General aviation student pilot accidents represent a substantial portion of all aviation accidents in the United States. Almost 50% of general aviation accidents involve student pilots. Analyzing historical accident reports is the most common approach to studying accident causation. The National Transportation Safety Board (NTSB) investigates all civil aviation accidents in the US. Using the NTSB data, I analyzed general aviation student pilot accidents in the US between 2013 and 2022. Results indicate that most accidents take place in California and Florida and can be attributed to student pilots between 18 and 65 years of age. Alaska and Maine had …

Comparative Analysis Of Command Protocols For Cubesat Data Handling Systems, Roman Dowling

Mechanical Engineering Undergraduate Honors Theses

Researchers at the University of Arkansas developed ARKSAT-1, a cubic satellite with the purpose of employing an LED with a tracking system to perform spectroscopic measurements of the atmosphere.

The control board of the satellite contained several microcontrollers which worked in concert to collect and manage data. Discussed in this report are the software programs developed for the microcontrollers, dual Arduino MKRZeros, utilized as data repositories and for control of satellite peripherals. The programs discussed in this project include an original existing command-response protocol and an improved batch-command protocol, each with its accompanying data handling and storage system. These programs …

A Study Of Varying Dielectric Constant And Thickness Of Dielectric Barrier Discharge Devices And Their Subsequent Plasma Actuation, Sharon Kardasz

Mechanical Engineering Undergraduate Honors Theses

The principles of air-breathing ion propulsion are relatively unestablished in the aerodynamic realm as traditional forms of combustion for propulsion systems have remained in use. However, due to increasing environmental, economic, and efficiency concerns of traditional combustion, interests in innovative propulsion methodologies, such as electric propulsion, are emerging. A primary technology of interest for use of ion propulsion is the Dielectric Barrier Discharge Device (DBD). Preliminary research conducted at the University of Arkansas has determined the most favorable DBD geometry. This work will continue the preliminary research to decipher the most favorable DBD configuration by varying dielectric thickness and dielectric …

Cosmic Object Space Management Operations System (C.O.S.M.O.S.), Riah Ivy, Tyler Bumpus, Gabriel Soter

Senior Design Project For Engineers

In the expansive realm of outer space, humanity has ventured into new territories, yet this progress is accompanied by challenges. Among the most significant challenges confronting space exploration today is the growing amount of space debris within low earth orbit. Satellites, spent rocket stages, and assorted fragments orbiting Earth present a considerable hazard to spacecraft and astronauts, and this issue is steadily worsening. For years, the task of remedying this orbital congestion has remained formidable and unresolved. This design provides a novel and innovative solution to this growing problem.

Effects Of Ferrite And Graphite Phases On Scratch Characteristics Of Nodular Cast Iron, Zhitong Xu, Ming Liu, Chenghui Gao, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

In this work, we conduct micro-scratch tests of nodular cast iron with Vickers indenter under constant normal load and investigate the effects of individual phases (i.e., ferrite and graphite phases) on the scratch charac- teristics of nodular cast iron. Using a bimodal Gaussian model to fit the experimental data of penetration depth, residual depth, elastic recovery rate, and scratch hardness, we calculate the contribution percentages of indi- vidual phases to scratch variables. The scratch variables are independent of the scratch speed used in this work, while the penetration depth increases linearly with increasing the normal load. There exists a large …

A Mechanical Model For Stress Relaxation Of Polylactic Acid/Thermoplastic Polyurethane Blends, Yi-Sheng Jhao, Hao Ouyang, Chien-Chao Huang, Fuqian Yang, Sanboh Lee

Chemical and Materials Engineering Faculty Publications

Polylactic acid (PLA) is considered a promising biodegradable polymer alternative. Due to its high brittleness, composite materials made by melt blending thermoplastic polyurethane (TPU) with PLA can enhance the toughness of PLA. To understand the forced aging caused by stress relaxation in polymer materials, this study explains the stress relaxation experiments of PLA/TPU blends with different mass ratios under applied strain through mechanical model simulations. The Kelvin representation of the standard linear solid model (SLSM) is used to analyze the stress relaxation data of TPU/PLA blends, successfully explaining that the Young’s moduli (E1 and E2) of springs decrease with increasing …

Comparative Analysis Of The Effects Of Post Processing On The Flexural Fatigue Endurance Of Additively Manufactured Ti-6al-4v, Cristian Banuelos

Open Access Theses & Dissertations

This study delves into analyzing the effects of various machining techniques on the flexural fatigue life of Ti-6Al-4V L-PBF specimens. The fatigue life and fracture behavior of specimens subjected to milling, grinding, polishing, and abrasive media blasting were compared. The findings reveal significant differences in the fatigue resistance between machined and non-machined parts. This study contributes to the understanding of the effects of post-processing on the durability of L-PBF manufactured components, offering insights for enhancing their application in critical aerospace and biomedical applications.

Feasibility Study For The Detection Of Damage To Composite Overwrapped Pressure Vessels With Phase Array Ultrasonic Testing, Jordan Scott Hitter

Open Access Theses & Dissertations

When discussing the field of Nondestructive Examination, there are various techniques and instrumentation that can be utilized for analysis of components. However, with newer technology and the development of newer forms of technique, it is critical to explore exactly how these can be applied. This work will aim to explore one newer technique, Phased Array Ultrasonic Testing, and determine the viability of its use for examining Composite Overwrapped Pressure Vessels (COPVs). Currently, the types of vessels have been used in a variety of ways such as in transportation vehicles. More notably, these vessels are used in aerospace applications hence the …

Adipose Stem Cell Response To Borophosphate Bioactive Glass, Nada A. Abokefa, Bradley A. Bromet, Rebekah L. Blatt, Makenna S. Pickett, Richard K. Brow, Julie A. Semon

Materials Science and Engineering Faculty Research & Creative Works

Silicate and Borate Bioactive Glasses Have Been Reported to Create Alkaline Conditions by Rapidly Releasing Ions When Reacting in Aqueous Solution. at Certain Levels, This Alkaline Solution Can Negatively Affect Cell Viability. Adding Phosphate Ions to the Glass Composition Can Control the Degradation Rate of Bioactive Glasses and Create a Neutral PH Environment. This Study Evaluated a Series of Boro phosphate Bioactive Glasses (BPBGs) with Nominal Molar Compositions 16Na₂O_-24CaO-XB₂O₃-(60-X) P₂O₅, Where X = 0, 40, or 60. the Phosphate (X0) Glass (PBG) Produced an Acidic Solution When Dissolved …

Reducing Carbon Emissions With Returned Concrete, John M. Maxwell Jr.

Construction Management

The concrete industry is one of the most energy-intensive sectors of construction. Specifically, the cement production aspect is the most energy intensive, and produces the most carbon emissions. Concrete, a material ubiquitous with nearly every facet of construction; certain types of structures are composed of nearly all concrete. Production of cement is one of the biggest contributors to emissions within the industry. There have been initiatives to reduce or offset emissions from this process, through things like carbon capture, and the purchase of carbon or emissions credits. The objective of this paper was to investigate a new method of carbon …

Little Free Library Project, Baylor Rembrandt

Construction Management

Little Free Library is a non-profit organization dedicated to promoting reading and literacy through community involvement by providing free book exchanges all over the world. The project was comprised of three phases, including design, construction, and installation. I began by identifying potential homeowners interested in hosting a library so that together we could come up with acceptable designs. This required close collaboration with the homeowners and resulted in unique, personalized designs for each library. Next came the construction phase, during which each library presented with its own challenges: the first library tested me with fundamental construction techniques; the second on …

Atascadero Little League - Snack Shack Window Renovation, Anthony J. Catania

Construction Management

Atascadero Little League is an essential part of the local community. It brings families together and provides youth with a place to develop their social skills, sportsmanship, and discipline all while getting outside and exercising. Little leagues are non-profit organizations, managed and operated by volunteers, who sacrifice personal time to give back to their local community. Paloma Creek Park is where Atascadero Little League hosts most of their games. The snack shack’s service window does not face the baseball field, forcing volunteers to rely on a small window in the side of the structure to view their child’s game. The …

Mems Optical Cavities For Low Power Communication., Jacob Schopp

Electronic Theses and Dissertations

This thesis discusses the use of MEMS (microelectromechanical systems) optical cavities for use in low power communication. MEMS optical cavities are thin air gaps between an actuated MEMS mirror and a fixed glass encapsulation. By moving the MEMS mirror the reflectivity of the MEMS optical cavity can be changed. This change in reflectivity can be used to transmit information passively by modulating reflected light intensity instead of generating new light using a light source. These MEMS optical cavities are demonstrated using optical fibers for illumination delivery and reflected light collection. In addition to being reflected for communication, the illuminating light …

Mechanical Property Simulations Of Ploybenzimidazole Membranes., Blake Alexander Clark

Electronic Theses and Dissertations

This work explores mechanical properties of membranes made of polybenzimidazole utilizing molecular simulations. These simulations researchers to narrow down polybenzimidazole membrane compositions to viable candidates. These simulations are quicker than current purely experimental methods. The increase in throughput would be achieved by eliminating compositions that have unfavorable mechanical properties through preliminary simulation work before moving onto experimental methods. Determining polybenzimidazole membranes’ mechanical properties experimentally would, therefore, allow for researchers to speed up research in areas such as fuel cells and electrolyzers that make use of polybenzimidazole membranes. This study uses Materials Studio and the COMPASS III forcefield to perform these …

Acoustofluidic Delivery Of Biomolecules To Cells: A Novel Approach For Preparing Car-T Cells., Madison C. Colebank

Electronic Theses and Dissertations

The continuous pursuit of effective methods for gene transfection in primary human T cells is crucial for advancing cell-based therapies. Viral vectors, currently used in cell-based therapies, involve a lengthy and costly process. This thesis explores the efficacy of coupling acoustofluidic and sonoporation techniques as an alternative non-viral gene transfection approach with primary T cells. Sonoporation, in conjunction with microbubbles, has been demonstrated to induce cavitation, resulting in the formation of pores in the cell membrane through which molecules can enter. Using flow cytometry, we compared the loading efficiency of primary T cells with that of Jurkat T cells to …

Development, 3d Printing, And Sintering Of Aluminum-Magnesium Alloy Pastes For In-Space Manufacturing Applications, Fatou Ndiaye

Electronic Theses and Dissertations

This study explores the additive manufacturing process of paste printing, sintering, and de-binding for fabricating aluminum-magnesium alloy components. The paste formulation involved combining aluminum powder with varying magnesium concentrations, utilizing acrylic polyol, solvent, and plasticizer to create a homogeneous mixture. Printing parameters were optimized to ensure continuous pressure for improved extrusion. Sintering conditions involved incremental temperature increases with nitrogen flow to remove solvents. Density measurements, tensile tests, and shrinkage calculations were conducted to assess part quality post-sintering. The study revealed significant improvements in part quality with 5 wt.% magnesium incorporation within aluminum, although density and tensile strength fell short of …

An Edge Computing System With Amd Xilinx Fpga Ai Customer Platform For Advanced Driver Assistance System, Tsun Kuang Chi, Tsung Yi Chen, Yu Chen Lin, Ting Lan Lin, Jun Ting Zhang, Cheng Lin Lu, Shih Lun Chen, Kuo Chen Li, Patricia Angela R. Abu

Department of Information Systems & Computer Science Faculty Publications

The convergence of edge computing systems with Field-Programmable Gate Array (FPGA) technology has shown considerable promise in enhancing real-time applications across various domains. This paper presents an innovative edge computing system design specifically tailored for pavement defect detection within the Advanced Driver-Assistance Systems (ADASs) domain. The system seamlessly integrates the AMD Xilinx AI platform into a customized circuit configuration, capitalizing on its capabilities. Utilizing cameras as input sensors to capture road scenes, the system employs a Deep Learning Processing Unit (DPU) to execute the YOLOv3 model, enabling the identification of three distinct types of pavement defects with high accuracy and …

Database And Machine Learning Model For Classifying Autism Spectrum Disorder From Smartphone Based Electroretinography, Rory Harris

Honors Scholar Theses

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder that negatively affects a patient’s cognitive and communication aptitude and, therefore, can severely impact that patient’s quality of life. Because of this, early diagnosis is paramount. In recent studies, electroretinography (ERG), which is a measure of the retina’s electrical response to a brief flash of light into the eye, has shown promise in detecting ASD. Access to these scans can provide early diagnosis, improving well-being. Current ERG devices are very expensive due to their on board processing capabilities. This paper aims to create an ERG device using a smartphone as the main …

Developing General Purpose Apps To Automate Image Analysis Of Wave-Augmented-Varicose-Explosion Atomization And Other Multi-Phase Interfacial Flows, Ethan Newkirk

Senior Honors Theses

Atomization involves disrupting a flow of contiguous liquid into small droplets ranging from one submicron to several hundred microns (micrometers) in diameter through the processes of exerting sufficient forces that disrupt the retaining surface tensions of the liquid. Understanding this phenomenon requires high-speed imaging from physical models or rigorous multiphase computational fluid dynamics models. We produce a MATLAB application that utilizes various methods of image analysis to quickly analyze and store mathematical data from detailed image analyses. We present a user with numerous tools and capabilities that provide results that deviate from 1.8% to 8.9% of the original image sequence …

Modeling Of Rotor Wake Vortex Dynamics And Interactions In Non-Homogenous Vertiport Environments, Garrison P. Shaw

Doctoral Dissertations and Master's Theses

The current research serves to analyze and study the effects ground forces can have on the thrust performance of a propeller in multiple different configurations. The current research utilizes an open source Computational Fluid Dynamics (CFD) software known as OpenFOAM to generate calculate and visualize these runs. The model used for this experiment is a hybrid model that employs both a Unsteady Reynolds-Averaged Navier-Stokes (URANS) and a detached eddy simulation using a hybrid Large Eddy Simulation (LES) via a KomegaSSTDDES model. This model serves to save computational time as well as allow for accurate results. The three cases run are …

Development Of A More Sustainable High And Ultra-High-Performance Concrete, Enrique Chirino Andalco

Theses and Dissertations

The urgent need to address climate change and environmental damage presents humanity with significant challenges that must be tackled quickly, not acting promptly will result in irreversible consequences, such as extreme weather events, public health risks, and water shortages, among other impacts.

Due to its enormous size and variety of uses, the construction industry is a key factor in addressing the climate challenge. Specifically, concrete as the most used construction material in the world is a good target for developing innovative and Sustainable improvements to reduce environmental impacts.

Using by-products from other industries in concrete manufacturing is a common and …

Machine Learning Predictive Models For Load Identification Of Railroad Bridges Subjected To Train-Induced Vibration, Md Masnun Rahman

Theses and Dissertations

The U.S. rail network is among the world's largest, safest, and most efficient. However, many its railway bridges, which play an essential role in its connectivity, are over 100 years old, showing signs of structural deterioration exceeding their practical service life. The increased weight and speed of modern trains also pose a risk to these bridges. Traditional load identification and monitoring technologies like Weigh-in-Motion (WIM) systems are rarely used on railway bridges due to their cost and practical limits. This thesis explores a cost-effective approach to utilize vibration sensors on railway bridges to identify and predict train load features (speed …

Numerical Study Of New Tuned Mass Friction Damper For Seismic Protection Of Civil Structures, Syed Muhammad Bilal Haider

Theses and Dissertations

Tuned Mass Friction Dampers (TMFDs) are passive control systems designed to mitigate vibrations in civil structures subjected to extreme lateral forces such as windstorms and earthquakes. The objective of this thesis is to propose a new TMFDs with enhanced energy dissipation capability for seismic protection of multi-story frame buildings. This new TMFD is termed as “Tuned Mass Multi-Sliding Friction Damper” (TMMSFD) consisting of multiple masses connected to the primary structure through linear springs and while sliding relative to each other at multiple sliding surfaces. TMMSFD offers an improved damping mechanism with reduced stick-slip motion effects compared to standard TMFDs which …

Model-Based And Model-Free Control Approaches In Subgrids: A Conceptual Review Of Control Strategies In Microgrids, Omobolade H. Abioye

Theses and Dissertations

Increased reliance on the power grid and concerns over climate change issues have resulted in the rapid adoption of renewable energy technologies. Consequently, it is necessary to consider how renewable energy resources are combined and controlled. The microgrid serves as the control center for distributed energy resources. This thesis paper introduces the microgrid elements and framework, its control strategies highlighting frequency and voltage control, and the prospects of artificial intelligence for control, considering two significant approaches. Key components of sub grids like the energy management system (EMS) and energy storage systems (ESSs) are discussed, and lastly, the …

Particle Swarm Optimization For Training Quadrotor Pid Controller, Eric Xavier Rodriguez

Theses and Dissertations

The objective of this research is to establish a fundamental approach to tuning PID (Proportional-Integral-Derivative) parameters for a simulated quadrotor drone. Implementing a PID controller for autonomous flight provides a straightforward and efficient method for monitoring and correcting robotic movement based on the robot's current state. However, applying a PID approach to a quadrotor's flight controller poses challenges, such as assigning multiple parameters to control an inherently under-actuated system. This includes the need to find optimal parameter values that reduce the likelihood of large overshoots and lengthy adjustment times. Ineffectively tuning PID parameters can have detrimental effects on autonomously …

Developing Resilient Defense Strategies Against Pheromone-Based Attacks In Foraging Robot Swarms, Ryan A. Luna

Theses and Dissertations

This thesis delves into the security of stochastic pheromone-based foraging algorithms within swarm robotic systems, a subset of foraging algorithms distinguished by their reliance on probabilistic decision-making mechanisms inspired by the natural world. Such algorithms face vulnerabilities in stigmergic communication that threaten to disrupt swarm operations. This research investigates these vulnerabilities, presenting two distinct contributions.

The first contribution examines the implementation of quarantine strategies as a defensive measure to isolate and mitigate the impact of fake resource attacks. By simulating these attacks, this study quantitatively assesses their detrimental effects on swarm efficiency and explores the efficacy …

Rsm For The Optimization Of Selective Laser Melting Process Parameters For Manufacturing Initial Layers Of Horizontal Overhang Structures, Prince Yaw Asamani

Theses and Dissertations

While prevalent in 3D printed objects, overhang features are difficult to print with selective laser melting due to the limitation of a purely vertical laser. To address this issue, overhang features are typically built on temporary supports, which are removed following printing. However, this results in wasted material and longer production time. Several authors have studied printing overhangs without support structures. However, there has not been a systematic approach to studying the effect of multiple process parameters on the quality of a printed overhang. This thesis investigates the effect of laser power, scanning speed, and hatch distance on the surface …

A Dedicated Lane Analysis For Supply Chain Resilience In The U.S.-Mexico Border: Cost-Comparison And Simulation Models, Carlo A. Zorola Gonzalez

Theses and Dissertations

Supply chains have been actively developing and implementing strategies to enhance resilience in response to various disruptive events like the COVID-19 pandemic, hurricanes, geopolitical tensions, and climate change. These strategies aim to address demand and supply imbalances, logistical challenges, and policy restrictions encountered in transborder commerce. One area significantly impacted by such disruptions is cross-border trade between the US and Mexico. Understanding these strategies is crucial for achieving supply chain resilience, defined as the ability of a supply chain to quickly adapt to sudden disruptions without affecting the flow of goods. In both the US-Mexico and US-Canada borders …

Understanding Timing Error Characteristics From Overclocked Systolic Multiply-Accumulate Arrays In Fpgas, Andrew S. Chamberlin

All Graduate Theses and Dissertations, Fall 2023 to Present

Artificial Intelligence (AI) is one of the biggest fields of research for computer hardware right now. Hardware accelerators are chips (such as graphics cards) that are purpose built to be the best at a specific type of operation. AI hardware accelerators are a growing field of research. Part of hardware in general is a digital clock that controls the pace at which computations occur. If this clock runs too quickly, the hardware won't have enough time to finish its computation. We call that a timing error. This paper focuses on studying the characteristics of timing errors in a small custom …