Engineering Commons^™

Durability Of Non-Metallic Materials For Additively Manufactured Heat Spreader Fabrication, Rafael Estrella

Mechanical Engineering Undergraduate Honors Theses

Power electronics are necessary to convert power from DC sources for AC applications. As this technology trends toward smaller packaging for denser power loads, the increased electrical losses result in deleterious excess heat. Thermal management devices are required to prevent the effects of thermal runaway from shortening the longevity of these modules. Nonmetallic jet impingement heat spreaders provide several benefits in terms of weight and performance over conventional cold plates while not accentuating EMI from the switches in the power module; however, the polymer makeup of the materials previously used for fabricating these devices raises durability concerns under the high …

Autonomous Material Refill For Swarm 3d Printing, William C. Jones

Mechanical Engineering Undergraduate Honors Theses

3D printing currently offers robust and cheap rapid prototyping solutions. While standard 3D printing remains at the periphery of mass production, the technology serves as a starting point for the development of swarm manufacturing. Since swarm manufacturing is predicated upon autonomy, swarm technology companies such as AMBOTS are seeking to minimize human involvement in the swarm’s functions. At present, the 3D printing swarm consists of the printers, a transporter which can take them between job sites, and the floor tiles which provide power and support the build surfaces. To add to this ecosystem, this project is focused on the design …

Analysis And Optimization Of The Two-Phase Series Capacitor Buck Dc-Dc Converter, Salahaldein Ali Aboajila Ahmed

Graduate Theses and Dissertations

Current sharing schemes for conventional multi-phase converters are based on sensing each phase current to deliver the current information to their controllers. In conventional buck converters, this fact may require a preset current sharing ratio at the expense of efficiency, which eventually requires a larger sensing circuit to achieve the sensing accuracy of each phase. Introducing the concept of automatic current sharing is one of the solutions to tackle this issue. Automatic current sharing (Current Sharing Mechanism CSM) is an advanced way to distribute heat generation in multi-phase switching topologies at full load. A two-phase series capacitor buck converter (2-pscB) …

Wave Interactions And Energy Cascade, Bailey Downing

Civil Engineering Undergraduate Honors Theses

Structural engineers design buildings and their components to withstand code-specified wind loads. The ASCE 7-16 manual sets the standards for calculating wind loads in the U.S. Depending on the velocity of wind, deflections may occur as wind passes through the building. The pressure reported from ASCE are based on wind tunnel measurements. The peak pressure from ASCE 7 is much less than what is measured from the field for a low-rise building. As an alternative economic tool, Computer modeling has been developed to help with this dilemma. Methods based on computational fluid dynamics (CFD) are used to calculate velocities and …

Evaluating The Effects Of Curing Methods On Bcsa Cement Concrete, Hannah Allen

Civil Engineering Undergraduate Honors Theses

BCSA cement is a type of cement that makes concrete set up much quicker than typical portland cement concrete. BCSA cement concrete also has a much higher compressive strength than that of portland cement concrete. This study was conducted to determine the effect of different curing conditions on the compressive strength of BCSA cement concrete.

The Impact Of Reliability In Conceptual Design - An Integrated Trade-Off Analysis, Tevari James Barker

Graduate Theses and Dissertations

Research presented in this paper focuses on developing models to estimate the systemreliability of Unmanned Ground Vehicles using knowledge and data from similar systems. Traditional reliability approaches often require detailed knowledge of a system and are used in later design stages as well as development, operational test and evaluation, and operations. The critical role of reliability and its impact on acquisition program performance, cost, and schedule motivate the need for improved system reliability models in the early design stages. Reliability is often a stand-alone requirement and not fully included in performance and life cycle cost models. This research seeks to …

Junction Temperature Estimation Of Silicon Carbide Power Module Using Internal Gate Resistance As Temperature Sensitive Electrical Parameter, Michael Sykes

Graduate Theses and Dissertations

The junction temperature of a power module is measured non-intrusively and uninterrupted in its application by analyzing the dependency of gate resistance to temperature. The circuit configuration proposed consists of altering the gate loop path and adding a basic peak detection circuit with an added low-pass filter to accurately measure the small differences seen during a temperature change on the internal gate resistance. The testing on this Silicon Carbide power module shows that the internal gate resistance has a positive temperature coefficient. This causes the current and the voltage drop on the gate loop sensing resistance to reduce as the …

Optimizing Virus Prefiltration For Biopharmaceutical Manufacturing, Solomon Isu

Graduate Theses and Dissertations

Virus filters are single-use devices that use a size-based separation process. In virus filters, contaminating virus particles are retained while the therapeutic molecules pass through the membrane pores. Virus filters are an essential component of the overall virus clearance strategy. Sections 1 and 2 of this dissertation provide an introduction and extensive review of monoclonal antibody (mAb) process development, where virus filtration is pivotal. In section 3, prefiltration studies were performed with an industrially relevant IgG1 type mAb using adsorptive and size-exclusion-based prefilters with different mechanisms of action. This mAb has an isoelectric point range of 7.1 to 8.0 and …

Predicting The Likelihood And Scale Of Wildfires In California Using Meteorological And Vegetation Data, Matthew Walters

Graduate Theses and Dissertations

Wildfires have devastating ecological, environmental, economical, and public health impacts through the deterioration of water and air quality, CO2 emissions, property damage, and lung illnesses. The early detection and prevention of wildfires allow for the minimization of these risks. The use of Artificial Intelligence (AI) in wildfire detection and prediction has been highly researched as a tool to assist firefighters in stopping wildfires in its early stages. The three common wildfire prediction categories include image and video detection, behavior prediction, and susceptibility prediction. Data such as climate, weather, vegetation, satellite images, and historical wildfire data is most commonly used. Many …

Diffusive Dynamics Of Biological Macromolecules In The Cytoplasm Of Live Bacteria, Asmaa Ali Sadoon

Graduate Theses and Dissertations

Bacteria are small organisms that play important roles in our bodies and in maintaining our surrounding environment. However, bacterial infections are considered as one of the health diseases that threatens the lives of humans. Resistance of bacteria to antibiotics has made treating bacterial infections more challenging. With the emergence of many developed optical techniques, it has become possible to study various biological mechanisms of molecules inside these small organisms with high resolution and precise localization. In this research, single particle tracking photoactivation localization microscopy (sptPALM) technique was used to investigate the dynamics of fluorescent histonelike nucleoid-structuring proteins (H-NS) in live …

Framework Of Hardware Trojan Detection Leveraging Structural Checking Tool, Rafael Dacanay Del Carmen

Graduate Theses and Dissertations

Since there is a significant demand for obtaining third-party soft Intellectual Property (IP) by first-party integrated circuit (IC) vendors, it is becoming easier for adversaries to insert malicious logic known as hardware Trojans into designs. Due to this, vendors need to find ways to screen the third-party IPs for possible security threats and then mitigate them. The development of the Structural Checking (SC) tool provides a solution to this issue. This tool analyzes the structure of an unknown soft IP design and creates a network of all the signals within the design and how they are connected to each other. …

Live Access Control Policy Error Detection Through Hardware, Bryce Mendenhall

Graduate Theses and Dissertations

Access Control (AC) is a widely used security measure designed to protect resources and infrastructure in an information system. The integrity of the AC policy is crucial to the protection of the system. Errors within an AC policy may cause many vulnerabilities such as information leaks, information loss, and malicious activities. Thus, such errors must be detected and promptly fixed. However, current AC error detection models do not allow for real-time error detection, nor do they provide the source of errors. This thesis presents a live error detection model called LogicDetect which utilizes emulated Boolean digital logic circuits to provide …

Supervised Representation Learning For Improving Prediction Performance In Medical Decision Support Applications, Phawis Thammasorn

Graduate Theses and Dissertations

Machine learning approaches for prediction play an integral role in modern-day decision supports system. An integral part of the process is extracting interest variables or features to describe the input data. Then, the variables are utilized for training machine-learning algorithms to map from the variables to the target output. After the training, the model is validated with either validation or testing data before making predictions with a new dataset. Despite the straightforward workflow, the process relies heavily on good feature representation of data. Engineering suitable representation eases the subsequent actions and copes with many practical issues that potentially prevent the …

Crystal Growth And Property Tuning Of Layered Magnetic Topological Semimetals, Krishna Pandey

Graduate Theses and Dissertations

The demand for energy-efficient devices has been growing rapidly due to the need for data-driven technologies and the global energy crisis. As device size approaches the atomic scale, the miniaturization of electronic devices may stop in the near future unless fundamentally new materials or device concepts are developed. The emergent topological materials with exotic properties show remarkable robustness against crystal lattice defects, which are promising for next-generation technology. These materials host exotic properties such as high mobility, large magnetoresistance, chiral anomaly, and surface Fermi arcs, etc. Among various topological materials, the ZrSiS-family materials exhibit two types of Dirac states, which …

Photoassisted Nanoscale Memory Resistors, Amir Shariffar

Graduate Theses and Dissertations

Memristors or memory resistors are promising two-terminal devices, which have the potential to revolutionize current electronic memory technologies. Memristors have been extensively investigated and reported to be practical devices, although they still suffer from poor stability, low retention time, and laborious fabrication processes.

The primary aim of this project was to achieve a device structure of quantum dots or thin films to address a fundamental challenge of unstable resistive switching behavior in memristors. Moreover, we aimed to investigate the effects of light illumination in terms of intensity and wavelength on the performance of the fabricated memristor. The parameters such as …

Exploring The Role Of Metabolites In Cancer And The Associated Nerve Crosstalk, Inah Gu, Emory A. Gregory, Casey Atwood, Sun-Ok Lee, Young Hye Song

Biomedical Engineering Faculty Publications and Presentations

Since Otto Warburg's first report on the increased uptake of glucose and lactate release by cancer cells, dysregulated metabolism has been acknowledged as a hallmark of cancer that promotes proliferation and metastasis. Over the last century, studies have shown that cancer metabolism is complex, and by-products of glucose and glutamine catabolism induce a cascade of both pro- and antitumorigenic processes. Some vitamins, which have traditionally been praised for preventing and inhibiting the proliferation of cancer cells, have also been proven to cause cancer progression in a dose-dependent manner. Importantly, recent findings have shown that the nervous system is a key …

Climate Change Impacts And Engineering Solutions, Dawson Oakley

Biological and Agricultural Engineering Undergraduate Honors Theses

With climate change entering the forefront of global issues, the need for sustainable practices that can provide for human welfare, social and economic development, and health has become more urgent than ever. Despite the recent increase in climate change impacts around the world, many people are still unaware of the severity of the situation. Changing public perception of these issues is the first step in enacting change and increasing accessibility to this information plays an important role.

Much of the information people consume today comes in the form of video, and it can be an effective tool to change knowledge …

Modeling Leaf Area Index And Canopy Height Using Growing Degree Days, Ellie J. Kuhn

Biological and Agricultural Engineering Undergraduate Honors Theses

As the global population increases and food security is recognized as a critical issue, crop growth prediction models help ensure the sustainability of reliable food sources. Using a prediction model based on temperature and simple, measurable field parameters, e.g., Leaf Area Index (LAI) or Canopy Height (H_can), may allow farmers and others to intervene mid-season with fertilizer, irrigation, or other inputs to obtain a better harvest.

This study aims to create a general model that could predict LAI and H_can values for numerous rice varieties using Growing Degree Days (GDD) as the time scale. The models use …

Exploring The Effects Of Varied Land Use On Elemental Concentrations Within Streams, Logan Jennings

Biological and Agricultural Engineering Undergraduate Honors Theses

It is well documented that human activity influences the chemistry of surrounding waters. As such, it is possible that there is a link between land use within a watershed and the chemical composition of the stream. The objectives of this study are to determine if varied land use does affect the concentrations of macronutrients and trace elements present in the streams of Northwest Arkansas, and if so, to determine what extent urban and agricultural development are responsible for these changes. Water samples were collected across 19 streams in the Northwest Arkansas region between January and March of 2022. Water samples …

Potato Processing In The Home: Sustainability And Nutritional Impacts, Aubin Payne

Biological and Agricultural Engineering Undergraduate Honors Theses

Potatoes are the world's fourth most consumed crop. Their versatility and long shelf-life make them a staple food for millions of people worldwide. Still, the increasing consumption of highly processed potato products in developed countries has damaged the public's appreciation of potatoes as a valuable source of essential nutrients. Additionally, as public awareness of environmental sustainability increases, the average consumer is more likely to value processing methods that mitigate environmental damage.

Researchers simulated several home storage and processing conditions to find out how nutrition and environmental impact are affected by the home processing timeline. Then, a nutrient analysis, life cycle …

Sensory Comparison Of Beer Carbonated Using Forced Carbonation And The Carbo Rock-It, Michala Smith

Biological and Agricultural Engineering Undergraduate Honors Theses

Craft brewing is a growing market which represents over 12% of beer produced in the United States. Dr. G Scott Osborn, PE invented the Carbo Rock-It™ to improve the carbonation process for craft breweries. The invention allows for shorter carbonation time and uses less CO₂, saving companies money and time. Because of the lack of gas losses through bubbling, Osborn theorized that the Carbo Rock-It could also prevent the “stripping of the nose” that can occur in traditional forced carbonation. Existing research supports the mechanism, as beer flavor and aroma volatiles have been detected during the release of …

Development Of An Equation To Correlate Brite Tank Temperature And Pressure To Beverage Carbonation Concentration, Devyn Meyer

Biological and Agricultural Engineering Undergraduate Honors Theses

The Carbo Rock-It™ is an invention created to carbonate beverages at craft breweries. One of the Carbo Rock-It’s main features is that it does not add a significant volume of undissolved gas bubbles to the brite tank in which the beverage is carbonated. This may allow temperature and pressure readings from the brite tank to be used to determine the concentration of dissolved carbon dioxide in the beverage continuously in real time. This eliminates the need for manual samplings, which could save breweries time and allow for more controlled, accurate carbonation. The goal of this project was to develop an …

Lattice Dynamics, Mechanical Properties, Electronic Structure And Magnetic Properties Of Equiatomic Quaternary Heusler Alloys Crticoz (Z = Al, Si) Using First Principles Calculations, Eesha Andharia, Hind Alqurashi, Bothina Hamad

Physics Faculty Publications and Presentations

First principles calculations are performed to investigate the thermodynamical stability, dynamical, mechanical, electronic and magnetic properties of CrTiCoZ (Z = Al/Si) novel quaternary Heusler alloys. A Y-type III atomic configuration is found to be the most stable structure for both compounds. The lattice constant values obtained using GGA-PBE approach are 5.9368 Å and 5.7853 Å for CrTiCoAl and CrTiCoSi, respectively. Using the value of elastic moduli for both the compounds, the computed Pugh’s ratio value is 2.5 and 2.7 for CrTiCoAl and CrTiCoSi, respectively, which is higher than 1.75, indicating both the compounds are ductile in nature. The melting temperatures …

21st Century Leadership: Leadership In Challenging Times, Adam Morris

Operations Management Presentations

Our global society has experienced unprecedented changes in the last couple years. The COVID-19 pandemic created drastic changes to our personal and professional lives. We went to a virtual work and learning environment almost overnight. People in leadership positions had to make impossible decisions on items no one has ever experienced. With all the changes that are happing in our world, what does it take to be a leader in today’s global society? Do basic leadership principles from 30 years ago still apply? Watch the latest installment of the MSEM/MSOM Lunch & Learn Webinar Series that will discuss these leadership …

The Causal Fairness Field Guide: Perspectives From Social And Formal Sciences, Alycia Carey, Xintao Wu

Computer Science and Computer Engineering Faculty Publications and Presentations

Over the past several years, multiple different methods to measure the causal fairness of machine learning models have been proposed. However, despite the growing number of publications and implementations, there is still a critical lack of literature that explains the interplay of causality-based fairness notions with the social sciences of philosophy, sociology, and law. We hope to remedy this issue by accumulating and expounding upon the thoughts and discussions of causality-based fairness notions produced by both social and formal (specifically machine learning) sciences in this field guide. In addition to giving the mathematical backgrounds of several popular causality-based fair machine …

Process- And Product-Related Foulants In Virus Filtration, Solomon Isu, Xianghong Qian, Andrew L. Zydney, S. Ranil Wickramasinghe

Biomedical Engineering Faculty Publications and Presentations

Regulatory authorities place stringent guidelines on the removal of contaminants during the manufacture of biopharmaceutical products. Monoclonal antibodies, Fc-fusion proteins, and other mammalian cell-derived biotherapeutics are heterogeneous molecules that are validated based on the production process and not on molecular homogeneity. Validation of clearance of potential contamination by viruses is a major challenge during the downstream purification of these therapeutics. Virus filtration is a single-use, size-based separation process in which the contaminating virus particles are retained while the therapeutic molecules pass through the membrane pores. Virus filtration is routinely used as part of the overall virus clearance strategy. Compromised performance …

Macrophage-Targeted Anti-Ccl2 Immunotherapy Enhances Tumor Sensitivity To 5-Fluorouracil In A Balb/C-Ct26 Murine Colon Carcinoma Model Measured Using Diffuse Reflectance Spectroscopy, Shelby N. Bess, Gage J. Greening, Narasimhan Rajaram, Timothy J. Muldoon

Biomedical Engineering Faculty Publications and Presentations

Background

Immunotherapy in colorectal cancer (CRC) regulates specific immune checkpoints and, when used in combination with chemotherapy, can improve patient prognosis. One specific immune checkpoint is the recruitment of circulating monocytes that differentiate into tumor-associated macrophages (TAMs) and promote tumor angiogenesis. Changes in vascularization can be non-invasively assessed via diffuse reflectance spectroscopy using hemoglobin concentrations and oxygenation in a localized tumor volume. In this study, we examine whether blockade of monocyte recruitment via CCL2 (macrophage chemoattractant protein-1) leads to enhanced sensitivity of 5-fluorouracil (5-FU) in a CT26-Balb/c mouse model of CRC. It was hypothesized that the blockade of TAMs will …

Microcystin-Lr Removal From Water Via Enzymatic Linearization And Ultrafiltration, Abelline Fionah, Cannon Hackett, Hazim Aljewari, Laura Brady, Faisal Alqhtani, Isabel C. Escobar, Audie K. Thompson

Chemical Engineering Faculty Publications and Presentations

Microcystin-LR (MC-LR) is a toxin produced by cyanobacteria that can bloom in freshwater supplies. This study describes a new strategy for remediation of MC-LR that combines linearization of the toxin using microcystinase A, MlrA, enzyme with rejection of linearized byproducts using membrane filtration. The MlrA enzyme was expressed in Escherichia coli (E. coli) and purified via a His-tag with 95% purity. Additionally, composite membranes made of 95% polysulfone and 5% sulfonated polyether ether ketone (SPEEK) were fabricated and used to filter a solution containing cyclic and linearized MC-LR. Tests were also performed to measure the adsorption and desorption of MC-LR …

Carrier Injection To In0.4Ga0.6As/Gaas Surface Quantum Dots In Coupled Hybrid Nanostructures, Jingtao Liu, Shiping Luo, Xiao Liu, Ying Wang, Chunsheng Wang, Shufang Wang, Guangsheng Fu, Yuriy I. Mazur, Morgan E. Ware, Gregory J. Salamo, Baolai Liang

Electrical Engineering Faculty Publications and Presentations

Stacking growth of the InGaAs quantum dots (QDs) on top of a carrier injection layer is a very useful strategy to develop QD devices. This research aims to study the carrier injection effect in hybrid structures with a layer of In0.4Ga0.6As surface quantum dots (SQDs), coupled to an injection layer of either one layer of In_0.4Ga_0.6As buried QDs (BQDs) or an In_0.15Ga_0.85As quantum well (QW), both through a 10 nm GaAs thin spacer. Spectroscopic measurements show that carrier capture and emission efficiency for SQDs in the BQD injection structure is better than …

The Use Of Electronic Nose In The Quality Evaluation And Adulteration Identification Of Beijing-You Chicken, Jingru Chen, Wenjie Yan, Yu Fu, Liang Wang, Xueze Lv, Ruitong Dai, Xingming Li, Fei Jia

Biological and Agricultural Engineering Faculty Publications and Presentations

The objective of this study was to reveal the secrets of the unique meat characteristics of Beijing-you chicken (BJY) and to compare the difference of quality and flavor with Luhua chicken (LH) and Arbor Acres broiler (AA) at their typical market ages. The results showed the meat of BJY was richer in essential amino acids, arachidonic acid contents, inosine monophosphate (IMP), and guanosine monophosphate (GMP). The total fatty acid and unsaturated fatty acid contents of BJY chicken and LH chicken were lower than that of AA broilers, whereas the ratios of unsaturated fatty acids/saturated fatty acids (2.31) and polyunsaturated fatty …