Engineering Commons^™

Design And Fabrication Of Invar Layup Tool Molds Using Additive And Subtractive Manufacturing, Matthew Lamsey

Masters Theses

The development of novel additive manufacturing technologies, such as Wire Arc Additive Manufacturing (WAAM), has opened the door for the fabrication of complex part geometries that could not be achieved with traditional manufacturing methods. Best practices for designing parts for fabrication with WAAM are still in their infancy. This thesis presents a novel design and fabrication framework for parts created using WAAM, which was realized through the fabrication of two demonstration composite layup tool molds. The framework includes design principles for WAAM, finite element simulation of part performance, metrological analysis of printed preforms, and considerations for closely integrating the WAAM …

Rare Earth-Doped Glass-Ceramic Scintillators As X-Ray Flat Panel Detector Substrates, Austin M. Thomas

Masters Theses

Digital radiography (DR) is an important two-dimensional imaging technique in the field of medicine that utilizes x-rays to form a digital image. DR employs a flat panel detector that converts incident x-rays, that have passed through the subject, to an electrical signal, which is used to create a digital image. The conversion from x-rays to electrical signals can be done either directly or indirectly. The direct method involves the x-rays being converted to an electrical signal via an array of semiconductors. The indirect method utilizes scintillators to absorb the x-rays and produce light in the visible spectrum, which is then …

Spin Effects Of Excited States In Organic Semiconductors And Hybrid Perovskites For Optoelectronics And Spintronics, Miaosheng Wang

Doctoral Dissertations

Organic semiconductors and organic-inorganic hybrid perovskites have demonstrated versatile functionalities for optoelectronic and spintronic applications. Research in this dissertation focuses on the spin effects of excited states in emerging organic semiconductor and hybrid perovskite systems to understand the fundamental working principle. The investigation on the spin effects in excited states can provide insightful guidance for the development of the next-generation organic and hybrid perovskite optoelectronics and spintronics.

In organic semiconductors, the excited states, namely, excitons can be characterized by the total spin angular momentum S=S_e+S_h of the constituent electron and hole, which determines the …

An Investigation Of Plastic Scintillators For Radiation Sensing And Mechanical Applications, Caleb J. Redding

Doctoral Dissertations

Plastic scintillators have uses in many fields including defense, high energy physics, health physics, and space applications. In recent years, work has been done to enhance a variety of plastic scintillator properties. These enhancements have largely targeted an increase of the intrinsic gamma efficiency, photopeak efficiency, mechanical robustness, the neutron pulse shape discrimination (PSD) figure of merit, and/or the timing resolution. This body of work seeks to examine these solutions both in a general radiation detection context and in the context of using the plastic scintillator as a frame component of a given detector system; in this work a hypothetical …

Wide Area Damping Control To Improve Transient Stability And Hardware-In-The-Loop (Hil) Implementation, Ibrahim Abdullah Altarjami

Doctoral Dissertations

In this dissertation, the impacts of WADCs on system transient stability are investigated, including system separation prevention under large disturbances and tie-line power transfer limit enhancement with consideration of a three-phase fault on one of the two tie-lines. The full Saudi power grid model in PSS/e is reduced for the real-time simulation on the Real-Time Digital Simulator (RTDS), and thus the developed WADCs can be tested in a controller hardware-in-the-loop environment in the future. The RTDS model is validated by comparing the full PSS/e model and the reduced PSS/e model under different contingencies. The WADCs are designed using a measurement-driven …

Capabilities Of A Closely-Packed, Wearable Radiation Detector Array: Source Localization, Directionality, And Multi-Modal Data Fusion, Carl Glenn Britt

Doctoral Dissertations

The capability of assigning source carrier probabilities by fusing both video and radiation data is demonstrated. Potential targets are automatically detected and tracked with computer vision techniques. Meanwhile, a newly developed method for exploiting the angular response of closely-packed radiation detector arrays points towards a radiation source using short, periodic measurements on the order of 1 s. Source carrier probabilities are then assigned after the object's movement measured from the video data stream is correlated with the radiation directionality estimates over a set period of time. In demonstrating source carrier probability assigned to moving sources, three main contributions were made. …

Development Of Data Science Tools For Part Qualification In Additive Manufacturing, Sujana Chandrasekar

Doctoral Dissertations

In recent years, metal additive manufacturing processes have become popular choices for part production especially for low volume, high complexity parts. To enable widespread adoption of these methods, it is essential to understand the link between process parameters and part properties. This is particularly because additive manufacturing processes cause inherently complex thermo-mechanical cycles and drastically different local process conditions within a part, compared to conventional manufacturing processes like casting and forging. Additionally, properties of feedstock material like metal powder impact final part properties. The focus of this dissertation is on development of data-driven methods using in situ monitoring, as a …

Engineered Switch Protein Inspired By Novel Protein Affinity Transition Mode, Liang Fang

Doctoral Dissertations

Many natural proteins involved in complex biological processes such as ligand binding and protein folding demonstrate multiple, allosterically-regulated conformational states, with protein activity regulated by effector molecules. The alpha L integrin and its inserted domain (I domain) is one example of such a protein. The binding of the effector molecule such as talin or filamin to the cytoplasmic domain of the integrin increases the binding affinity between I- domain and its ligand intercellular adhesion molecule-1, known as ICAM-1.There are multiple models attempting to describe the mechanism responsible for the change in binding affinity. According to research conducted by our lab, …

Development Of A Particle Filter-Based Prognostic Model To Predict Maintenance Dependent Processes, Hang Xiao

Doctoral Dissertations

Components and systems in industrial processes undergo wear and degradation until they are either replaced or repaired. Maintenance actions, mostly imperfect repairs, may not entirely reduce the degradation and may expedite future degradation rates. Those repair and maintenance actions should be considered in prognostics models to accurately predict the components’ health conditions.

Different mechanical components have different fault modes in complex engineering systems, such as Nuclear Power Plants (NPPs). The change of a process variable may be caused by the degradation of a few different components. Effective ways to decouple the fault modes are required to predict each component's Remaining …

Manipulation Of Excited States In Organic-Inorganic Hybrid Perovskite Optoelectronic Devices, Jia Zhang

Doctoral Dissertations

In recent years, a huge success on photovoltaic and light emitting has been achieved in the field of organic-inorganic hybrid perovskites owing to the superior optoelectronic properties of excited states. Regulating the primary excited states is the foundation of developing multi-functional optoelectronics, including the light-emitting, photovoltaic and lasing actions. By revisiting the photophysical processes of excited states, some new strategies are suggested to further pushing the efficiency of perovskites forward. This thesis focuses on the manipulation of excited states through combining optoelectronic devices, from excited states generation to excited charge carrier transport.

Chapter 1 presents a basic introduction to excited …

Investigation Of Microstructure Heterogeneity Using Multi-Length Scale Characterization Of Additively Manufactured 316l Ss Components For Nuclear Applications, Amy J. Godfrey

Masters Theses

Additive manufacturing allows for near net shape components to be manufactured with complex geometries and internal cooling channels while simultaneously allowing for microstructure control. Additive manufacturing has an added benefit of the possibility of removing the post processing needs associated with traditional nuclear component manufacturing. The microstructure of components built using laser powder bed fusion has been shown to be greatly affected by the build parameters. By altering the laser power, laser velocity, and the spot size the microstructure and, possibly, nanoscale partitioning may be tailored. In this study, nanoscale partitioning was confirmed to be the result of an abrupt …

Unmanned Aerial System For Radioactive Source Search, William J. Lynch

Masters Theses

A novel system of airborne radiation survey and source localization is built and tested. In the United States the National Nuclear Security Administration is currently using a two tier approach that uses a manned fixed wing airplane and manned helicopter to survey nuclear disaster zones. The novel system proposed takes the operators out of harm's way and allows for higher resolution radiation surveys at a cheaper cost. This proposed system also allows the operators to locate a source rapidly in the event that a source is stolen or lost. This proposed system is configurable for most radiation detectors that are …

Using Survey Data To Understand Ridesourcing In Tennessee: Who, Where, When, And Why?, Cassidy Kilmer Crossland

Masters Theses

With companies like Uber and Lyft leading the way, ridesourcing has grown and continues to grow in popularity in the United States since its introduction just over ten years ago. While research on this new transportation mode has largely focused on national level trends and studies of large metropolitan areas, little has been written about its impacts in smaller and mid-sized cities and states. This paper aims to understand the socioeconomic characteristics and travel behavior trends of those using ridesourcing in less studied regions, using Tennessee as a case study. This thesis has three parts: a literature review of past …

A Secure Architecture For Defense Against Return Address Corruption, Grayson J. Bruner

Masters Theses

The advent of the Internet of Things has brought about a staggering level of inter-connectivity between common devices used every day. Unfortunately, security is not a high priority for developers designing these IoT devices. Often times the trade-off of security comes at too high of a cost in other areas, such as performance or power consumption. This is especially prevalent in resource-constrained devices, which make up a large number of IoT devices. However, a lack of security could lead to a cascade of security breaches rippling through connected devices. One of the most common attacks used by hackers is return …

Temperature Sensitive Paint Investigation Of A Cylinder Induced Shockwave Boundary Layer Interaction, Caleb Bell

Masters Theses

A urethane based temperature sensitive paint was employed to measure the surface temperature characteristics of both a cylinder perpendicular to a Mach 2.3 flow and the floor of the tunnel with varying gaps between the base of the cylinder and the tunnel floor. The first goal of this study was to determine the effectiveness of a temperature sensitive paint at providing quantitative and qualitative temperature data on supersonic flow interactions in a standard supersonic blow down wind tunnel. The second goal was to determine the heat transfer and surface temperature of the cylinder and the areas of the tunnel wall …

Quantifying Tree Canopy Contributions To Stormwater Runoff Reductions In Urban Watersheds Of The Southeastern United States, Matthew C. Howard

Masters Theses

Urban stormwater is a major contributor to surface water degradation in the United States, prompting cities to invest in ways to naturally capture, store, and slowly release runoff through “Green Infrastructure” (GI). One often overlooked potential contributors to stormwater management are urban trees, an integral part of a given city’s GI. Interception is of particular interest and describes a tree’s ability to capture and store rainfall, reducing the volume of stormwater that can degrade urban streams during storm events. While rainfall interception for full canopy, forested environments is well studied, limited research is available that characterizes the interception of open-grown …

A Communications Testbed For Testing Power Electronic Agent Systems, Benjamin R. Dean

Masters Theses

As power electronic system (PES) continue to incorporate complex intra-system communication, understanding and characterizing this communication has become a complex task. Knowing how a system’s communication will behave is vital to ensuring proper operation of these systems. This thesis proposes and outlines a communication testbed that streamlines the development and testing of the communications between the components of PES, and further presents the characterization of communication protocol utilized in these multi-agent PESs. These communication protocols include MQTT, Modbus, or User Datagram Protocol (UDP). Understanding the different behavior of these protocols presents is paramount for the design of PESs.

Bioretention Cell Performance Under Shifting Precipitation Patterns Across The Contiguous United States, Matthew Weathers

Masters Theses

As climate change produces shifts in precipitation patterns, communities will need to understand how the performance of green stormwater infrastructure (GSI) may be impacted. Bioretention cells are one of the most commonly implemented forms of GSI for their ability to reduce peak discharge and filter pollutants and are a vulnerable component of stormwater infrastructure. Projections in future climate indicate that bioretention cells may be at risk of losing their existing function due to deviations in precipitation frequency and intensity. General circulation models (GCMs) downscaled to regional climate models (RCMs) can provide climate change projections at a high spatial resolution but …

Correlating Fracture Toughness And Surface Roughness For A Ductile Epoxy Adhered To Aluminum Substrates, Kurt Ryan Smith

Masters Theses

Adhesively bonded joints are used across multiple disciplines as an efficient and cost effective method for reinforcing, repairing, or creating new structures. Sufficient understanding of the bond line characteristics of the adhesive is necessary to properly design a reliable bonded joint and ensure a long service life. It is well understood that surface preparation has a significant impact on these interface characteristics as a given level of surface roughness achieves mechanical interlocking between the resin and metal and is important to prevent premature interfacial failure [1]. The goal of this study is to characterize the fracture toughness values for an …

Design Of A Cable-Driven Manipulator For Large-Scale Additive Manufacturing, Phillip Chesser

Masters Theses

Additive manufacturing of concrete is a growing field of research, yet current motion platforms do not offer viable routes towards large scale deployable systems. This thesis presents the design and analysis of a novel cable-driven robot for use in large scale additive manufacturing. The system developed, termed SkyBAAM, is designed to be easily deployable to a construction site for on-site additive manufacturing of buildings and other large structures. The design philosophy behind this system is presented. Analysis of this system first explores the kinematics, and stiffness as a function of cable tension. Analysis of the workspace and singularities is also …

Experimental Investigation Of Spray Cooling/Heating Of A Near-Isothermal Hydro-Pneumatic Energy Storage System, Saiid Kassaee

Masters Theses

Proposing experimental investigation of spray cooling/heating of a near-isothermal, scalable, efficient, high density, hydro-pneumatic integrated energy storage system; capable of spray cooling/heating during gas compression/expansion and capable of excess heat integration. The invented Ground-Level Integrated Diverse Energy Storage (GLIDES) is an energy storage technology capable of storing energy in high-pressure vessel using hydro-pneumatic concept. Indicated roundtrip efficiencies of 98% can be reached using the proposed technology marking an isothermal compression/expansion energy storage.

Development Of A Converter-Based Testing Platform And Battery Energy Storage System (Bess) Emulator For Microgrid Controller Function Evaluation, Dingrui Li

Masters Theses

The microgrid has attracted increasing research attention in the last two decades. Due to the development of renewable energy resources and power electronics technologies, the future microgrid will trend to be smarter and more complicated. The microgrid controller performs a critical role in the microgrid operation, which will also become more and more sophisticated to support the future microgrid. Before final field deployment and test, the evaluation and testing of the controller is an indispensable step in the controller development, which requires a proper testing platform.

However, existing simulation-based platforms have issues with potential numerical oscillation and may require huge …

Examining The Empirical Relationship Between Subjective Fatigue And Employee Work Engagement In A Heavy Workload Manufacturing Environment, Prashanth Balasubramanian

Masters Theses

The purpose of this study was to examine the empirical relationship between Subjective Fatigue and Employee work engagement among employees working under heavy workload conditions in Tennessee, USA. The questionnaire was developed by reviewing extant literature and the factors that were chosen were subjected to exploratory factor analysis. Post elimination of the weakly loaded factors, a questionnaire based on the selected factors was designed to measure the subjective levels of fatigue. The data was collected from two manufacturing company sites from East Tennessee and was subjected to analysis using IBM SPSS and SmartPLS softwares. As a part of the SEM …

Analysis Of Hardware Accelerated Deep Learning And The Effects Of Degradation On Performance, Samuel C. Leach

Masters Theses

As convolutional neural networks become more prevalent in research and real world applications, the need for them to be faster and more robust will be a constant battle. This thesis investigates the effect of degradation being introduced to an image prior to object recognition with a convolutional neural network. As well as experimenting with methods to reduce the degradation and improve performance. Gaussian smoothing and additive Gaussian noise are both analyzed degradation models within this thesis and are reduced with Gaussian and Butterworth masks using unsharp masking and smoothing, respectively. The results show that each degradation is disruptive to the …

Thorium Dioxide Extraction From Monazite Ore, Katherine Glass

Chancellor’s Honors Program Projects

No abstract provided.

Design, Construction, And Flight Of A Remote-Controlled Aircraft For The 2020-21 Aiaa Dbf Competition, Jonathan A. Dixon, Caleb Weatherly, Satyam Mistry, Killian Samuels, Ethan Cerrito, Caleb Morgan, Sanghyeok Park, Sam Pankratz, Jamison Murphree

Chancellor’s Honors Program Projects

No abstract provided.

Thorium Dioxide Extraction From Monazite Ore, Jason Pan, Niall Phelan Terry, Katherine Glass, Eli Jenkins, Connor High

Chancellor’s Honors Program Projects

No abstract provided.

Robot Object Detection And Locomotion Demonstration For Eecs Department Tours, Bryson Howell, Ethan Haworth, Chris Mobley, Ian Mulet

Chancellor’s Honors Program Projects

No abstract provided.

Site Development Services At Mcghee Tyson Airport, Luke A. Edwards, Tyler Bomar, Scott Cole, Samuel Enders, Matthew Dearborn

Chancellor’s Honors Program Projects

No abstract provided.

Approximation Of The Time Rate Of Consolidation For Hydraulically Placed Fine Coal Refuse Using A Variable Coefficient Of Consolidation Method, Cyrus Jedari, Eric Drumm, Angelica Palomino

Faculty Publications and Other Works -- Civil & Environmental Engineering

Terzaghi’s consolidation theory assumes strain in soil due to applied overburden pressure is small, and permeability and thus the coefficient of consolidation (C_v) remain constant during consolidation. Although valid for soft soil consolidation, the C_v for hydraulically placed slurry materials with low solids content may change significantly during the consolidation process as the material transitions from a slurry to a solid. In this study, a spatial and temporal variable C_v was used to predict the time rate of consolidation of fine coal refuse placed in an impoundment as a slurry. The results suggest the variable …