Engineering Commons^™

Microwave Characterization Of Polymeric Microparticle Morphology, Gabriel D. Cutter

Honors College Theses

Biological cell function and overall health are highly defined by the cell’s morphology. Sorting cells based on their shape is recently a major interest to the biomedical field for the future of medical treatments and health diagnostics. This work presents a new shape-based particle sorting technique using a novel microwave sensing system as a step toward biological cell sorting. The new sensing system consists of a grounded coplanar waveguide (GCPW) transmission line that simultaneously serves as a single-particle microfluidic channel and a microwave sensor, which is paired with a microwave interferometer to boost signal-to-noise ratio (SNR). Polystyrene microspheres, a common …

Design And Data-Driven Identification Of A Quadruped Robot, Dakota Rufino

All Theses

The existence of nonlinearities and the lack of sufficient equations are fundamental challenges in modeling, analyzing, and controlling complex systems. However, recent developments revolutionizing the study of dynamical systems. An emerging method in nonlinear dynamical systems is the Koopman operator theory, which provides us with key advantages in performing the modeling, prediction, and control of nonlinear systems. The linear system representation allows us to leverage linear stability analysis. The first section of this thesis briefly covers the construction of a quadrupedal robot, a sufficiently complex nonlinear dynamical system, for the use of analyzing data-driven modeling techniques. The second section details …

Radic Voice Authentication: Replay Attack Detection Using Image Classification For Voice Authentication Systems, Hannah Taylor

Undergraduate Honors Theses

Systems like Google Home, Alexa, and Siri that use voice-based authentication to verify their users’ identities are vulnerable to voice replay attacks. These attacks gain unauthorized access to voice-controlled devices or systems by replaying recordings of passphrases and voice commands. This shows the necessity to develop more resilient voice-based authentication systems that can detect voice replay attacks.

This thesis implements a system that detects voice-based replay attacks by using deep learning and image classification of voice spectrograms to differentiate between live and recorded speech. Tests of this system indicate that the approach represents a promising direction for detecting voice-based replay …

Assessment Of Joule Heating Properties Of Various Solder Alloys In Bga Assembly, Jimmy-Bao D. Le

Material Science and Engineering Theses - Archive

The continuing demands for smaller, yet higher performance devices have resulted in many revolutionary changes in device packaging in recent years, including the change in package form factors, structure, and the type of solder alloys used for the assembly. Because solder joints are exposed to various electrical and thermo-mechanical stresses, not only at use condition but also during their process into the assembly, they are prone to failure. Especially concerned in this respect is the current density that the solder joint is subjected to as it determines the level of Joule Heating (JH), thus the solder temperature, significantly affecting the …

Enhancing Microstructure, Composition Homogeneity, And Mechanical Properties In Laser Powder Bed Fused Metallic Alloys: Design, Fabrication, And Evaluation, Bahzad Farhang

Mechanical and Aerospace Engineering Dissertations - Archive

ABSTRACT: Over the past five decades, Nickel-based and Titanium-based alloys have become increasingly popular materials. As the manufacturing industry for these alloys has advanced, the demand for fabricating complex parts with enhanced mechanical properties at elevated temperatures has grown. Laser Powder Bed Fusion (LPBF), one of the most prevalent additive manufacturing techniques, has been employed successfully to produce these alloys. Nonetheless, there is still considerable effort being made to improve the microstructural, compositional, and mechanical properties of LPBF-processed components. In this study, we focused on adjusting the multi-scale microstructure and composition of LPBF-fabricated Nickel-based and Titanium-based alloys. The first objective …

Theoretical And Numerical Analysis Of Thermal Runaway Propagation In Li-Ion Battery Packs, Dhananjay Mishra

Mechanical and Aerospace Engineering Dissertations - Archive

Strategies to prevent or minimize propagation of thermal runaway in a pack of Li-ion cells are critically needed to ensure safe operation, storage and transportation. While significant literature already exists on thermal runaway simulations, several key questions of practical relevance have remained unaddressed. This work presents multi-mode heat transfer simulations to predict the onset and propagation of thermal runaway in a pack of cylindrical Li-ion cells. The impact of inter-cell gap and thermal properties of the interstitial material on onset and propagation of thermal runaway is studied. It is shown that high interstitial thermal conductivity promotes thermal runaway propagation. However, …

Steady State And Transient Analysis Of Heat Transfer In A Porous Fin With Radially Outwards Pressure-Driven Flow, Muhammad Mehdi Abbas

Mechanical and Aerospace Engineering Theses - Archive

Thermal management and energy storage problems often utilize extended surfaces, also known as fins for enhanced heat transfer. Today fins are used in a wide range of devices including but not limited to microelectronic components and large heat exchanger. Traditional fins as well as porous fins with flow orthogonal to fin direction have been subject of past research. There is very few academic literature available on porous fins with pressure driven flow along fin direction. While thermal conduction is usually the dominant mode of heat transfer in a solid fin, the use of porous fins that include advective thermal transport …

Development Of Vortex Box (Vbox) And Vortex Tip (Vtip) Filament Free-Wake Rotor Models, Casey Will Matsler

Mechanical and Aerospace Engineering Theses - Archive

Rotor models span from simple static and first order expressions to high fidelity, numerical computations and across the spectrum each model is good for different purposes. The use of models has improved with time and technological capability but choosing the right model for the task is important. A survey of rotor models is performed to identify a rotor model flexible enough for providing high to moderately high-fidelity results without significantly sacrificing computational time. The model chosen is intended to be for general purposes and applicable across a wide range of operating conditions. From the survey, a blade element rotor model …

Evaluation Of Solder Alloys For Bga Package: A Comparative Reliability Study Using Ansys Computational Analysis, Yashvanth Muthegowda

Mechanical and Aerospace Engineering Theses - Archive

Temperature cycling failure of solder joints in Ball Grid Array (BGA) packages has become a critical issue in electronic manufacturing. This thesis specifically characterizes three different lead-free solder alloys (Pure Indium, SAC-387, and SAC-Q) in BGA solder joints using two different printed circuit board (PCB) thicknesses (1mm and 0.7 mm). The analysis considers the non-uniform temperature distribution caused by the main heat source, the die, and the resulting deformation of the package due to the mismatch in the coefficient of thermal expansion (CTE) between components used in BGA. Finite element (FE) models are created in ANSYS mechanical package environment to …

Advancement Of An Inhouse Aerospace Vehicle Design Synthesis System Through The Introduction Of A Novel Database-Knowledgebase System And By Improving The Geometry And Aerothermodynamic Disciplinary Processes, Samuel Atchison

Mechanical and Aerospace Engineering Theses - Archive

Throughout the years of aerospace vehicle design, the process in which a vehicle is designed has drastically improved from being primarily developed through trial and error, to using sophisticated synthesis systems. While the trial-and-error process had its uses with providing the fundamental knowledge of how aircraft behave and can be designed, the increase in knowledge and technology allowed the possibility of more vehicle configurations to be explored without the need to build each one. This increase should have led to a revolution of vehicle designs, and while there have been some novel ones, it seems that the general design of …

Numerical Modeling Of Damper Configuration And Arrangements For Analysing Thermal Stratification In Modular Air Handling Units, Rohit Antony Raymonds

Mechanical and Aerospace Engineering Theses - Archive

Although air handling units are well established and maturated there are opportunities to optimize and improve the overall thermal and flow performance to reduce the carbon footprint of an air-cooled data center. Airside economization (ASE) arrangement to use cold outdoor air to minimize mechanical cooling energy was substantial progress in minimizing the power usage effectiveness (PUE) for data centers. ASE is an arrangement of ducts and dampers with the necessary controls to meet the cooling requirements. Dampers play a significant role in regulating the mass flow rate of the air and in mixing the two air streams: cold outdoor air, …

Effects Of Metal Organic Frameworks In Polyether Block Amide Elastomer, Joe Alex

Mechanical and Aerospace Engineering Theses - Archive

Metal-organic frameworks (MOFs) are highly porous materials that find extensive applications in gas absorption and separation in recent years. These hybrid materials can be designed with specific pore sizes and voids to selectively filter gases. PEBAX (MV 1074) is a commercially available polyether block amide copolymer generally used in gas separation applications. In this study, we characterize two different MOFs by means of a dispersion study and create a medium for them to be evenly dispersed into the aforementioned copolymer matrix. Polymer composite fibers are extruded using a twin-screw extruder and a winding unit at pre-determined parameters for winding speed …

Impact Of Immersion Cooling On Thermo-Mechanical Properties Of Non-Halogenated Core, Mohan Sai Ramalingam

Mechanical and Aerospace Engineering Theses - Archive

The rise in demand for modern high-power systems, which require fast processing and frequent data storage, has resulted in an exceptional and unprecedented increase in power density and heat generation within data centers. This eventually led to the need for advanced cooling techniques that can address the challenges of managing the heat produced by the data centers. As per Moore's law and Dennard's scaling, the power densities of chips and the heat flux generated by servers are continuously increasing. [1] As a result, the dissipation of heat at the chip level has also increased, posing a significant challenge for thermal …

Investigating The Impact Of International Education On Cultural Understanding, Health Disparities And Collaboration Through Project-Based Learning, Breanna Kilgore

Biomedical Engineering Undergraduate Honors Theses

Global health is an interdisciplinary field emphasizing international health issues, causes, and solutions based on cultural and global understanding. We have all witnessed how crucial global health is with the global COVID-19 crisis that has affected everyone. To effectively work to solve global health issues, people from different backgrounds must work together to complete a common goal. Before problem solving begins, gaining a basic understanding of cultural differences and collaborating with different people is an essential skill to have. Previous studies have demonstrated the usefulness of study abroad experiences and international service-learning opportunities in promoting collaborations, cultural competency and personal …

Correlation Of Intracellular Metabolites With Optical Metabolic Imaging In Polarized Macrophages As Indicators Of Metabolic Reprogramming, Abby Claire Denison, Shelby Bess

Biomedical Engineering Undergraduate Honors Theses

Macrophages are a type of immune cell that are characterized by their ability to differentiate into various active phenotypes based on environmental stimuli. They can generally be classified as one of two extremes: inflammatory/M1 or wound-healing/M2. Macrophage populations in vivo, however, are rarely homogenous, and since macrophages play vital roles in the immune response, particularly in the context of the tumor microenvironment (TME), it’s important to be able to investigate and understand heterogenous macrophage populations to develop more effective treatments. Recently, autofluorescence imaging such as multiphoton microscopy and fluorescence lifetime imaging microscopy (FLIM) of metabolic cofactors NADH and FAD have …

Optimizing Three-Dimensional Bioengineered Co-Cultures For The Study Of Fibrotic Spinal Cord Injury, Sarah Aly

Biomedical Engineering Undergraduate Honors Theses

Spinal cord injuries (SCIs) have major physical implications on those affected^[1]. There are two main types of scarring that occur after injury; they are known as the glial and fibrotic scar. The injured site causes an altered micro-environment which transforms astrocytes from their normal to reactive state, thus inhibiting axonal regeneration. The effect of reactive astrocytes on fibrotic scarring is not fully understood due to limited study^[2,3]. Using Three-Dimensional (3D) bioengineered co-cultures of astrocytes and neuroblasts the pathological environment can be replicated and manipulated to further the study of fibrotic scarring. Temperature casted co-cultures were successfully …

Study Of Alloy Effect On Electromigration In Sn Solder Alloys, Geng Ni

Material Science and Engineering Dissertations - Archive

This dissertation presents experimental results about the alloy effect on the Electromigration (EM) of Sn in Sn-based binary and ternary alloys. By using cross-stripe configuration, the alloy effect on EM of Sn can be characterized from marker polarity, and the migration of alloy element under EM can be measured from marker front motion. In the dissertation, the mechanism of alloy effect on EM of Sn, “Two-Phase equilibrium”, will be introduced. Electromigration is a phenomenon where metallic atoms are migrated at the direction of electron flow under high current density. In response to the demands for greater speed and smaller size, …

Analyze The Effect Of Urbanization And Development Over The Flow Regime And River Channel Hydraulics Of The Big Bear Creek Channel, Machiraju Pakasasana Kashyap

Civil Engineering Theses - Archive

This thesis focuses on investigating the influence of urbanization and development on flow regime and river channel hydraulics in the Bear Creek watershed, Texas using a comprehensive set of hydrologic and 1D/2D coupled hydraulic model. The Bear Creek watershed, located in North Texas, has experienced rapid urbanization and land development in recent years, raising concerns about the potential impacts on hydrological processes and the hydraulic behavior of the river system. To address these concerns, this research utilizes an integrated modeling approach, combining the HEC-HMS and HEC-RAS software tools, to assess changes in flow rates and simulate their effects on river …

Performance Of Percussion Driven Earth Anchors For Riverbank Slope Stabilization: Comprehensive Laboratory And Field Studies, Natnael Tilahun Asfaw

Civil Engineering Dissertations - Archive

ABSTRACT: The unpredictability of the stability of embankment slopes is a recurring problem that threatens the safety of the traveling public, as it compromises the integrity of the structures built on them. Slopes that undergo seasonal variations of stream flow are of particular concern, as they are usually located under a bridge structure that spans a stream, and the meandering of the stream flow, the seasonal variations of the flow depth, and the velocity in the channel induce scouring and increase the risk of the bridge failing. Departments of transportation have long attempted to address these concerns by designing systems …

Optimization Of Primary Chemical Feed Rates And Application Points At An Existing Potable Water Treatment Plant, Brently Keith Jordan

Civil Engineering Theses - Archive

Due to a major upset in the treatment processes for the Dallas County Park Cities Municipal Utility District caused by a required change in treatment techniques, an optimization study was conducted to find the best treatment strategies for the primary coagulation, flocculation, and settled processes for the treatment plant. A methodology for determining how to optimize jar testing while injecting both ferric sulfate and calcium hydroxide in an almost simultaneous manner was developed, and a large number of jar tests were conducted to determine both the best dosages and the best application points of the two chemicals. As a result …

An In Vivo Biocompatibility Analysis Of A Novel Tissue Regeneration Matrix Using A Pig Model, Shamar Thomas

All Theses

The goal of this project is to develop an injectable bead scaffold to promote tissue regeneration in the void created by lumpectomy and to alleviate post lumpectomy problems by preventing local recurrence and minimizing surgical-related infections. Microbeads were synthesized from collagen type I and crosslinked with tannic acid to form the basis for this injectable therapeutic. Tannic acid acts as a therapeutic anticancer agent. The action mechanisms of tannins in breast cancer cells have been studied with studies showing tannins to be cytotoxic to cancer cells in a dose-dependent manner. Tannic acid induces apoptosis in breast cancer cells via caspase …

Novel Microdevices To Analyze Toxic Volatile Organic Compounds., Sujoy Halder

Electronic Theses and Dissertations

There has been a growing interest to measure volatile organic compounds (VOCs) in a range of environmental applications. The presence of toxic VOCs in the air has been associated with serious health problems including asthma, central nervous system dysfunction, cardiovascular disease and cancer, etc. Different analytical instruments such as gas chromatography-mass spectrometry (GC-MS) and sensor systems, such as metal oxide sensors are used to analyze VOCs. However, challenges still exist in the detection of airborne VOCs because of their trace concentration and interference with complex gas mixtures. In this dissertation, two microfabricated devices, a sensor array and a micropreconcentrator were …

Investigation Of Degradation Of Solar Photovoltaics: A Review Of Aging Factors, Impacts, And Future Directions Toward Sustainable Energy Management, Eklas Hossain

Electrical and Computer Engineering Faculty Publications and Presentations

The degradation of solar photovoltaic (PV) modules is caused by a number of factors that have an impact on their effectiveness, performance, and lifetime. One of the reasons contributing to the decline in solar PV performance is the aging issue. This study comprehensively examines the effects and difficulties associated with aging and degradation in solar PV applications. In light of this, this article examines and analyzes many aging factors, including temperature, humidity, dust, discoloration, cracks, and delamination. Additionally, the effects of aging factors on solar PV performance, including the lifetime, efficiency, material degradation, overheating, and mismatching, are critically investigated. Furthermore, …

Optimizing Wedding Venue Selection Process Using Integer Programming, Luis Rodriguez

Theses/Capstones/Creative Projects

Choosing the right wedding venue can be extremely difficult for the unsuspecting engaged couple. There is a myriad of variables that must be taken into account prior to the illustrious wedding date; these variables include the option for a reception, the location, and food requirements, to name a few. Consequently, the typical couple seems to spend multiple months researching and visiting many wedding spaces. However, even though months go into planning, it still is not a guarantee that all variables are accounted for. Furthermore, without a wedding planner, these couples may second-guess their chosen site due to seemingly arduous issues …

Feasibility Study: Application Of Steel Sheet-Piles For The Abutment Of Water-Crossing Bridges In Nebraska, Seunghee Kim, Jongwan Eun, Chung R. Song, Chungwook Sim, Hung Phi Van, Basil Abualshar, Ramin Ziaei Tabari

Nebraska Department of Transportation: Research Reports

The overall goal of this study is to investigate the anticipated performance of steel sheet-pile bridge abutments to encourage its wider application to not only new construction but also repair and replacement of existing water-crossing bridges in Nebraska. For this purpose, this study first reviewed several bridge cases with axially loaded sheet pile abutments, as well as previous in-depth studies related to the bearing capacity of sheet piles. Then, this study conducted the large-scale direct shear tests to better understand the interaction between sheet pile and soil. As a result, about four-fifths of the internal friction angle of fill sand …

Automated Visualization Pipeline For Near Real-Time Risk Management System, Paris Joslin

Industrial Engineering Undergraduate Honors Theses

In modern society, technological capabilities and the amount of data readily available to users continue to grow exponentially. Many have adopted these new capabilities but lack the infrastructure needed to efficiently utilize high-powered software and programs. Without a method to collect, store, and process large datasets in real-time, individuals and businesses can quickly become overwhelmed, inhibiting effective decision-making processes. There is potential to improve decision-making abilities by enhancing the computing infrastructure. To accomplish this task, we will explore the ideas surrounding High Performance Computing (HPC) and data visualization software. High Performance Computing is the ability to process data and perform …

Comparative Design Space For Bistable Composites: An Integrated Framework Of Optimization, Finite Element Analysis, And Experimental Testing, Jonathan Bolanos

All Theses

Bistable composites are a class of advanced materials that can actuate between two stable shapes, making them attractive for a wide range of engineering applications. However, designing these composites to achieve optimal performance remains a challenging task. To address the challenge, this research develops an integrated framework that combines a genetic algorithm optimization technique, finite element analysis in Abaqus, and experimental testing to explore the design comparative space for square bistable composites composed of DA 409 carbon fibers. This leads to the study of generating an optimization algorithm to account for the relationship between the chances of a successful maximum …

Laser Stabilization Through Optical Turbulence, Liam Vanderschaaf

All Theses

Laser jitter presents a significant issue in the fields of laser communication and sensing. There are two main categories of positional noise in regards to the instantaneous centroid of a laser propagating over long distances: jitter resulting from optical turbulence and jitter resulting from mechanical vibrations. Optical turbulence was generated using Clemson University’s Variable Turbulence Generator (VTG). The VTG is capable of creating a desired level of optical turbulence that is comparable to atmospheric conditions with fried parameters greater than 0.3 cm. A gaussian laser was transmitted through the VTG and a system of Fast Steering Mirrors and Position Sensing …

A Hidden Spider Web Of Roots: Utilizing Ground Penetrating Radar To Uncover Laterally Expansive Roots Of An Oak Tree, Megan Lapkoff

All Theses

Roots are critical to understanding tree health, subsurface biomass, and overall tree root stability. However, accessing tree roots is difficult and traditional methods used to quantify roots harm or kill the tree. Ground penetrating radar (GPR) provides a non-invasive way to characterize subsurface roots without harming the tree. GPR provides high-resolution data and the ability to collect data with high spatial coverage, making it an ideal tool for characterizing roots. GPR works by detecting contrasts in dielectric permittivity or electromagnetic (EM) velocity at interfaces between materials. Small scattering objects, like roots, generate predictable artifacts called diffraction hyperbolas. Diffraction hyperbolas will …

Development And Evaluation Of Machine Learning Models For Fugitive Methane Detection And Intensity Prediction, Jacquan Pollard

All Theses

The environmental impacts of global warming driven by fugitive methane (CH4) emissions have catalyzed significant research initiatives in developing novel technologies that enable proactive and rapid detection of CH4 emissions. This study evaluated the performance of data-driven machine learning (ML) models using support vector machines (SVM) to detect the presence of trace CH4 emissions and the corresponding intensity amongst various meteorological conditions. The author used simulation data comprising various meteorological parameters such as temperature, relative humidity, wind speed, water vapor, pressure, precipitation rate, and a parameter possessing trace concentrations of CH4 emissions. The novelty of the SVM models developed in …