Engineering Commons^™

Dynamics Modeling Of Molten Salt Reactors, Visura Umesh Pathirana

Doctoral Dissertations

The abundance of energy is a necessity for the prosperity of humans. The rise in energy demand has created energy shortages and issues related to energy security. Nuclear energy can produce vast amounts of reliable energy without many of the negative externalities associated with other competing energy sources, such as coal and natural gas. As a result, public interest in nuclear power has increased in the past decade. Many new types of nuclear reactor are proposed. These nuclear reactor designs feature many passive technologies that can operate without external influence. Reactors that feature advanced passive safety features are catagorized as …

Stress Relaxation Cracking In 347h Austenitic Steel Weldments Under Various Heat Treatments: Experiments And Modeling, Yi Yang

Doctoral Dissertations

347H austenitic stainless steel exhibits exceptional creep and corrosion resistance, rendering it an exemplary candidate for pipeline materials, particularly in mid- to high-temperature working conditions. However, due to constraints in component dimensions, welding has been chosen as the preferred method for joining pipeline systems extensively employed in nuclear power plants, fossil fuel plants, and petrochemical companies. The welding process entails the accumulation of residual stress during the cooling stage, along with the introduction of microstructure evolution. Moreover, the residual stress field and microstructure continuously evolve under service conditions, thereby intensifying the susceptibility of crack initiation and propagation. The initial residual …

Development Of A Portable, Tileable, Dual-Particle Radiography System, Christian Xavier Young

Doctoral Dissertations

A scalable, portable, multi-particle neutron radiography device has been developed using commercial-off-the-shelf-parts. The IDEAS ROSSPAD readout module was selected for use in developing the radiography panel due to its single-wire Power-over-Ethernet (PoE) connectivity and its tileable form factor. Each ROSSPAD detector is paired with an 8 by 8 array of 6-mm-pitch Sensl J-Series silicon photomultipliers (SiPMs). With both single and multi-ROSSPAD testing, a detection package consisting of a 3-mm-thick sheet of EJ-200 plastic scintillator and a 3-mm-thick sheet of acrylic light spreader was coupled to the SiPM board face. After both quality assurance of the detector packages and the calibration …

A Two-Diameter Helical Endmill Beam Model For Tool Tip Dynamics Prediction With Application To Milling, Emma D. Betters

Doctoral Dissertations

The aim of this dissertation is to describe the dynamic response of helical endmill geometries to enable the use of receptance coupling substructure analysis (RCSA) to predict the tool tip vibration response of arbitrary tool-holder-spindle-machine combinations. The tool tip vibration response, or receptance, is a key input for milling stability prediction. Currently, a measurement is required to determine the tool tip receptance for each tool-holder-spindle-machine combination, which may not be possible in production environments. In the RCSA approach, the spindle receptances are measured once and archived, while the tool and holder are modeled. Tool tip receptances are predicted by analytically …

Enhanced Bioretention Modeling At The Catchment-Scale: An Integrated Drainmod-Urban And Swmm Approach, Ghada Diab

Doctoral Dissertations

Bioretention systems are increasingly being adopted in stormwater management as an effective measure to promote infiltration and restore more natural hydrology in urbanized watersheds. Given the significant financial investment in these practices, reliable bioretention models are necessary to predict the effectiveness of these practices prior to installation. One such model, DRAINMOD-Urban (DM-Urban), was recently developed to produce hydrographs with a high temporal resolution at the site-scale, showing substantial promise during initial testing. However, the dataset used for initial testing was limited, consisting of one bioretention area with minimal occasions of overflow. Additionally, DM-Urban is an input-heavy model and there is …

Static And Dynamic State Estimation Applications In Power Systems Protection And Control Engineering, Ibukunoluwa Olayemi Korede

Doctoral Dissertations

The developed methodologies are proposed to serve as support for control centers and fault analysis engineers. These approaches provide a dependable and effective means of pinpointing and resolving faults, which ultimately enhances power grid reliability. The algorithm uses the Least Absolute Value (LAV) method to estimate the augmented states of the PCB, enabling supervisory monitoring of the system. In addition, the application of statistical analysis based on projection statistics of the system Jacobian as a virtual sensor to detect faults on transmission lines. This approach is particularly valuable for detecting anomalies in transmission line data, such as bad data or …

Atomic-Level Mechanisms Of Fast Relaxation In Metallic Glasses, Leo W. Zella

Doctoral Dissertations

Glasses are ubiquitous in daily life and have unique properties which are a consequence of the underlying disordered structure. By understanding the fundamental processes that govern these properties, we can modify glasses for desired applications. Key to understanding the structure-dynamics relationship in glasses is the variety of relaxation processes that exist below the glass transition temperature. Though these relaxations are well characterized with macroscopic experimental techniques, the microscopic nature of these relaxations is difficult to elucidate with experimental tools due to the requirements of timescale and spatial resolution. There remain many questions regarding the microscopic nature of relaxation in glass …

Transportation System Performance And Traveler Behavior In The Context Of A Systemwide Shock: Applications Of Data Science Toward A Sustainable Future, A. Latif Patwary

Doctoral Dissertations

The COVID-19 pandemic, a systemwide shock, has left a long-lasting and significant impact on transportation systems. It has contributed to a shift in travel behavior, with many people turning to work from home (WFH) and online shopping. This shift has led to a reduction in vehicular travel. However, the pandemic witnessed increased crash fatalities despite a reduction in overall crashes, disproportionately affecting disadvantaged communities (DACs). The main question arising from these pandemic-related issues is what we can learn to improve transportation systems and shape future travel behavior. Therefore, this dissertation aims to investigate how the transportation system changed during COVID-19 …

Exploring Soil Microbial Dynamics In Southern Appalachian Forests: A Systems Biology Approach To Prescribed Fire Impacts, Saad Abd Ar Rafie

Doctoral Dissertations

Prescribed fires in Southern Appalachian forests are vital in ecosystem management and wildfire risk mitigation. However, understanding the intricate dynamics between these fires, soil microbial communities, and overall ecosystem health remains challenging. This dissertation addresses this knowledge gap by exploring selected aspects of this complex relationship across three interconnected chapters.

The first chapter investigates the immediate effects of prescribed fires on soil microbial communities. It reveals subtle shifts in porewater chemistry and significant increases in microbial species richness. These findings offer valuable insights into the interplay between soil properties and microbial responses during the early stages following a prescribed fire. …

3d Experimental Studies Of Temperature And Crystallographic Effects On Creep And Strength In Rock Salt, Amirsalar Moslehy

Doctoral Dissertations

Salt domes utilization as storage reservoirs in the energy sector has led to extensive studies on rock salt’s mechanical and geothermal behavior. These important facilities’ safety and serviceability rely on understanding rock salt’s compressive strength and creep behavior under various loading directions, water contents, in-situ stresses, and temperatures. Despite numerous studies on rock salt’s mechanical behavior in the literature, there are still many unanswered questions about rock salt’s behavior. This dissertation was aimed at utilizing state-of-the-art experimental techniques such as 3D synchrotron micro-computed tomography (SMT) and 3D x-ray diffraction (3DXRD) along with hundreds of compression and creep experiments to enhance …

Fourier Analysis And Optimization Of Inductive Wireless Power Transfer For Electric Vehicle Charging, Andrew P. Foote

Doctoral Dissertations

With the growth of electric vehicle (EV) popularity, different charging options to increase user convenience and reduce charging time such as high power wireless charging are increasingly being developed and researched. Inductive wireless power transfer (WPT) systems for EVs must meet specifications such as stray field, battery power and voltage operating range, efficiency, and ground clearance. The coil geometry and design have a large impact in meeting these constraints. Typical design approaches include iterative analysis of predetermined coil geometries to identify candidates that meet these constraints.

This work instead directly generates WPT coil shapes and magnetic fields to meet specifications …

Characterization Of Radiotolerance In Potato And Development Of A Gamma Radiation Phytosensor., Robert Graham Sears

Doctoral Dissertations

As humans pursue space travel and nuclear energy, the risk of harm from ionizing radiation increases. On Earth or in space, plants are essential to our personal and environmental health. Plants serve as sentinels, bioremediators and food sources in areas of high ionizing radiation, therefore it is essential to understand how ionizing radiation affects plant biology. This work aimed to understand plant responses to ionizing radiation in the potato chassis and apply that knowledge to generate novel phenotypes for nuclear energy and space applications. The first gamma radiation phytosensor was developed for monitoring at standoff distances greater than three meters. …

Effect Of Seawater And Temperature Upon Carbon Fiber/Vinyl Ester (Cfve) Composites And Its Constituents, Vivek Chawla

Doctoral Dissertations

An experimental and computational investigation has been carried out to: (1) develop micromechanical characterization techniques for polymeric composites and (2) evaluate the effects of seawater and temperature upon the micro- and macro-response of the carbon fiber vinyl ester composites (CF/VE). Compression properties degradation due to short-term and long-term exposure to seawater is evaluated. A 12-16 % reduction in compression strength is observed due to long-term exposure to seawater, which is attributed to a decrease in interfacial shear strength (IFSS) due to long-term exposure to seawater. The developed Push-out methodology is used to characterize the IFSS. The presented approach consistently yields …

Additively Manufactured Nature Inspired Morphology For Redesign: Advancing Next Generation Energy Systems, Vanshika Singh

Doctoral Dissertations

To meet cleaner energy goals and increasing demand, energy systems such as gas turbines and power plants are required to be operated under harsh loading conditions like higher temperatures and pressures, fluctuating loads, and corrosive environments. Advanced manufacturing techniques such as additive manufacturing (AM) have put us on the trajectory for next-generation system designs, allowing complex geometries and high-temperature alloys with tailored material properties. We need new and systematic design philosophies to use AM's unique characteristics prudently. For a given functionality, nature tends to provide similar solutions in animate and inanimate structures. We propose to take inspiration from nature's repetitive …

Characterization Of Lignin Structural Variability And The Associated Application In Genome Wide Association Studies, Nathan D. Bryant

Doctoral Dissertations

Poplar (Populus sp.) is a promising biofuel feedstock due to advantageous features such as fast growth, the ability to grow on marginal land, and relatively low lignin content. However, there is tremendous variability associated with the composition of biomass. Understanding this variability, especially in lignin, is crucial to developing and implementing financially viable, integrated biorefineries. Although lignin is typically described as being comprised of three primary monolignols (syringyl, guaiacyl, p-hydroxyphenyl), it is a highly irregular biopolymer that can incorporate non-canonical monolignols. It is also connected by a variety of interunit linkages, adding to its complexity. Secondary cell wall …

Functional Cementitious Composites With Micro-Sized Particulate Fillers For Additive Construction And Energy-Efficient Buildings, Adam Brooks

Doctoral Dissertations

With a growing energy demand, the development of sustainable and energy efficient building materials is growing rapidly. Numerous researches have focused on low carbon footprint construction materials, high-performance thermal insulations, high-performance façade, and thermal energy storage. Among these, the development of functional cementitious composites has attracted significant attention due to its potential utilities in building energy reduction and decarbonatization efforts. For example, fly ash cenospheres have been used as micro-size lightweight fillers to achieve low density and thermal conductivity. The use of phase change materials (PCM) in concrete has been studied to answer energy demands. While their inclusion into concrete …

Developing A Flexible System For A Friendly Robot To Ease Dementia (Fred) Using Cloud Technologies And Software Design Patterns, Robert James Bray

Masters Theses

In this work, we designed two prototypes for a friendly robot to ease dementia (FRED). This affordable social robot is designed to provide company to older adults with cognitive decline, create reminders for important events and tasks, like taking medication, and providing cognitive stimulus through games. This project combines several cloud technologies including speech-to-text, cloud data storage, and chat generation in order to provide high level interactions with a social robot. Software design patterns were employed in the creation of the software to produce flexible code base that can sustain platform changes easily, including the framework used for the graphical …

Utilization Of Integer Programming For Scheduling Maintenance At Nuclear Power Plants, Timothy Gallacher

Doctoral Dissertations

This thesis develops a thought that naturally explores three specific motifs for solving the complexities of scheduling maintenance at Nuclear Power Plants (NPP). The first chapter of this paper will develop the initial thought around creating a schedule for a given work week, including all the various constraints inherent to this problem. Such constraints include but are not limited to personnel availability, allowable component out-of-service time, and the Plant Risk Assessment. The objective function being to minimize the total cost of worker’s compensation for that given week.

The second chapter addresses the question of whether this simple schedule can be …

Development And Biomechanical Analysis Toward A Mechanically Passive Wearable Shoulder Exoskeleton, Seyyed Morteza Asgari

Doctoral Dissertations

Shoulder disability is a prevalent health issue associated with various orthopedic and neurological conditions, like rotator cuff tear and peripheral nerve injury. Many individuals with shoulder disability experience mild to moderate impairment and struggle with elevating the shoulder or holding the arm against gravity. To address this clinical need, I have focused my research on developing wearable passive exoskeletons that provide continuous at-home movement assistance. Through a combination of experiments and computational tools, I aim to optimize the design of these exoskeletons.

In pursuit of this goal, I have designed, fabricated, and preliminarily evaluated a wearable, passive, cam-driven shoulder exoskeleton …

Additive Manufacturing Of Magnetic Materials For Electric Motor And Generator Applications, Haobo Wang

Doctoral Dissertations

This work details the research into the 3D Printing, also known as Additive Manufacturing (AM), of both impermanent and permanent magnets. This work also details the research in enabling such AM magnets in electrical machine applications, primarily motors and generators. The AM processes of many types of magnets are described in detail. The material properties of such AM magnets are also described. The two main types of AM magnets that are discussed in detail are AM NdFeB, and AM Silicon Steel. The implementation of AM NdFeB as rotor magnets, and the implementation of AM Silicon Steel as rotor and stator …

Characterizing The Structure And Radiation Resistance Of Weberite-Type Complex Oxides, Igor M. Gussev

Doctoral Dissertations

Weberite-type A₃BO₇ oxides, where A is a trivalent rare earth and B is a pentavalent element like Ta, have been a focus of research due to the discovery of the weberite-type local atomic arrangement in ceramics with a defect-fluorite structure. Earlier studies primarily examined their long-range structures, leaving gaps in understanding their short-range atomic behavior. This thesis investigates various weberite-type tantalates across all structural scales. There has been debate over the long-range structure of Y₃TaO₇, a medium-sized rare earth tantalate oxide, particularly regarding its spacegroup symmetry. This work identifies Y₃TaO_{7 …}

Exact Models, Heuristics, And Supervised Learning Approaches For Vehicle Routing Problems, Zefeng Lyu

Doctoral Dissertations

This dissertation presents contributions to the field of vehicle routing problems by utilizing exact methods, heuristic approaches, and the integration of machine learning with traditional algorithms. The research is organized into three main chapters, each dedicated to a specific routing problem and a unique methodology. The first chapter addresses the Pickup and Delivery Problem with Transshipments and Time Windows, a variant that permits product transfers between vehicles to enhance logistics flexibility and reduce costs. To solve this problem, we propose an efficient mixed-integer linear programming model that has been shown to outperform existing ones. The second chapter discusses a practical …

The Nuclear System-Of-Systems Capabilities Analytic Process, Robert Boone Gilbreath

Doctoral Dissertations

This work includes the first known capabilities-based vulnerability analysis process able to evaluate a system of systems exposed to nuclear weapon environments: the Nuclear System-of-Systems Capabilities Analytic Process (NuSCAPTM). This approach, executed by an automated Python® application, calculates the magnitudes of eight nuclear weapon environment quantities by calling on the US Strategic Command Probability of Damage Calculator (PDCALC) code, the Los Alamos National Laboratory Simple Nuclear Effects Calculator (SNEC) program, and the Monte Carlo N-Particle® (MCNP®) code. Calculated nuclear weapon environment values are compared with user-provided dysfunction thresholds for all components, subsystems, and systems in the model to determine the …

Modular Composite Sandwich Structures For Thermal And Structural Retrofitting Of Existing Buildings, Marc Al Ghazal

Masters Theses

Around 40% of global energy consumption and 30% of worldwide carbon dioxide (CO2) emissions are attributed to buildings. Most of this consumption is dedicated to ensuring thermal comfort. The goal of this research was to develop and field validate retrofit solutions to improve the energy efficiency of buildings. Exterior cladding panels were designed and tested to ensure adequate thermal and structural performance. Sandwich panels (glass fibers reinforced polymer (GFRP) skins and polymeric foam cores) were fabricated using the vacuum assisted resin transfer molding (VARTM) process. Extruded polystyrene (XPS) and polyurethane (PU) foams were compared as core materials through a series …

A Case Study In Cmos Design Scaling For Analog Applications: The Ringamp Ldo, Steven Corum

Masters Theses

As CMOS process nodes scale to smaller feature sizes, process optimizations are made to achieve improvements in digital circuit performance, such as increasing speed and memory, while decreasing power consumption. Unfortunately for analog design, these optimizations usually come at the expense of poorer transistor performance, such as reduced small signal output resistance and increased channel length modulation. The ring amplifier has been proposed as a digital solution to the analog scaling problem, by configuring digital inverters to function as analog amplifiers through deadzone biasing. As digital inverters naturally scale, the ring amplifier is a promising area of exploration for analog …

Surface Location Error In Robotic Milling: Modeling And Experiments, Richard Henry Swan Jr.

Masters Theses

Robotic milling offers new opportunities for discrete part manufacturing as an alternative to milling using large conventional machine tools. The advantage of industrial robots is their large work volume, configurability, and comparatively low cost. However, robots are significantly less stiff than conventional machine tools, which can lead to poor surface finish, low machining accuracy, and low material removal rates. The purpose of this research is to predict the geometric errors, or surface location errors, that occur in a robotic mulling tool path, validate these predictions with machining tests, and compensate these errors by tool path modification. Compared with conventional machine …

Preparation Of The Ej301d, A Deuterated Liquid Organic Scintillation Detector, For Spectroscopy Of Fast And High Energy Neutrons, Albert Du

Masters Theses

The focus of this research is on the preparation of a deuterated organic scintillation detector for fast and high energy neutron spectroscopy. The underlying physics of organic scintillation detectors, the process in which a neutron undergoes interaction with the detector material, as well as the readout and data processing procedure is introduced.

For methodology, a comprehensive setup of an EJ301-D deuterated organic scin- tillation detector is detailed. This includes algorithmic development for three distinct purposes. Firstly, it involves the creation of iterative unfolding algorithms, specif- ically the GRAVEL and Maximum Likelihood Expectation-Maximization (MLEM)

algorithm. The second development is conformal binning …

Uncertainty Quantification Framework For Design Optimization, Austin Ryan Williams

Masters Theses

Difficulty to obtain neutron sources of interest have driven the need for optimization
techniques to tailor a neutron generator as a replacement. A proposed solution uses
off-the-shelf neutron sources coupled with an energy-tuning assembly to mimic the
source of interest (i.e. AmLi, AmBe, thermonuclear fission spectra, etc.). These
energy-tuning assemblies have been designed with complex optimization algorithms
coupled with Monte Carlo simulations. These new system surrogate designs often
do not have an experimental counterpart for validation and comparison, and lack
non-statistical uncertainties. This work aims to improve confidence in the predictions
by providing a tool for fast uncertainty quantification to …

Analysis Of An Electrospray Thruster With A Concave Propellant Meniscus, Adam Nicholas Huller

Masters Theses

The low thrust, high specific impulse, and low mass of electrospray thrusters (ETs) make them ideal for maneuvering nanosatellites, especially with the new requirement to deorbit a satellite within five years of completing its mission. These innovative thrusters use electrohydrodynamic principles of electrospray (ES) to provide thrust. These principles have been subject to much research over the past decade, though much more research is needed to fully understand the underlying physics of these thrusters. The first part of this study establishes a procedure for analyzing the theoretical thrust performance of an ET, by using propellant properties and well-documented ES scaling …

Integrated Modeling And Monitoring For A Healthy And Sustainable Building Environment, Yifang Xu

Doctoral Dissertations

The transmission of airborne diseases indoors is a significant challenge to public health. Buildings are hotspots for viral transmission, which can result in adverse effects on human health and quality of life, especially considering that individuals spend approximately 87% of their time indoors. The emergence of the COVID-19 pandemic has highlighted the importance of considering health aspects during the development of sustainable built environments. Consequently, maintaining a healthy, sustainable, and comfortable built environment represents a major challenge for facilities management teams. However, research on the infection risks associated with emerging pandemics is still in its infancy, and the effectiveness of …