Engineering Commons^™

Determination Of Critical Experiment Correlations Via The Monte Carlo Sampling Technique, William Jay Marshall

Doctoral Dissertations

Critical benchmark experiments are the foundation of validation of the computational codes used in criticality safety analyses because they provide a basis for comparison between the calculated results and the physical world. These experiments are often performed in series varying a limited number of parameters to isolate the effect of the independent parameter. The use of common materials, geometries, machines, procedures, detectors, or other shared features can create correlations among the resulting experiments. Most validation techniques used in criticality safety practice do not treat these correlations explicitly, and the effect of this is unclear as the correlations themselves are not …

Double Differential Neutron Yields Produced By Proton, Helium, And Iron Interactions In Thick Aluminum Targets, Natalie Ann Mcgirl

Doctoral Dissertations

Recent calculations of galactic cosmic ray (GCR) transport in enclosed, shielded space environments indicate that a minimum dose equivalent is achieved with aluminum shielding thicknesses near 20 g/cm² [grams per centimeter squared]. Increases in the absorbed dose and dose equivalent with shielding thicknesses above 20 g/cm² are believed to be caused by the production of light ions and neutrons in the thick shielding. However, uncertainties surround these calculations due to limited cross section and yield data for high-energy projectiles incident on thick targets. Thick-target neutron yields are particularly valuable measurements since they are produced over a wide range …

A Wide Area Hierarchical Voltage Control For Systems With High Wind Penetration And An Hvdc Overlay, Yidan Lu

Doctoral Dissertations

The modern power grid is undergoing a dramatic revolution. On the generation side, renewable resources are replacing fossil fuel in powering the system. On the transmission side, an AC-DC hybrid network has become increasingly popular to help reduce the transportation cost of electricity. Wind power, as one of the environmental friendly renewable resources, has taken a larger and larger share of the generation market. Due to the remote locations of wind plants, an HVDC overlay turns out to be attractive for transporting wind energy due to its superiority in long distance transmission of electricity.

While reducing environmental concern, the increasing …

Novel Fission Track Detection For Identification And Characterization Of Special Nuclear Materials, Jonathan Allen Gill

Doctoral Dissertations

Fission track detection and analysis is used primarily in nuclear safeguards to identify special nuclear material. Identification of isotopic ratios is a crucial step in understanding the intended use of nuclear material and the nature of the materials production cycle. Unfortunately, this methodology uses etchable track detectors that require significant expertise and intensive labor to process.

This study developed a novel method using lithium fluoride (LiF) as a fluorescing nuclear track detector to conduct fission track analysis for isotopic prediction of uranium enrichment. Individual latent tracks produced by fission products were observed in LiF for the first time. These tracks …

Development Of High-Performing Polydimethylsiloxane-Based Membranes For Carbon Dioxide Separation, Tao Hong

Doctoral Dissertations

Membrane separation is highlighted as one of the most promising approaches to mitigate the excessive CO₂ [carbon dioxide] emission, due to its significant reduction of energy cost compared with many conventional separation techniques. Unfortunately, the separation performance of current membranes does not meet the practical CO₂/N₂ [nitrogen] separation requirements. And due to the huge volume of industrial flue gas, membranes with exceptionally high permeability are needed for practical reasons.

Currently, the separation mechanism of most polymeric membranes is based on size-sieving. However, this method is not sufficient for CO₂/N₂ separations due to the …

Electrochemical Hydrogen Separation Via The Solid Acid Electrolyte Cesium Dihydrogen Phosphate, David Leon Wilson

Doctoral Dissertations

Abundant, inexpensive, high purity molecular hydrogen as a medium for energy distribution is potentially enabling for adoption of alternative electricity generation schemes. Steam reforming of natural gas remains the dominant method of producing large amounts of hydrogen. However, this process also creates by-products, most notably, carbon monoxide and carbon dioxide. Separation to ultra-high purity hydrogen from these syngas reformate streams by traditional methods, such as pressure swing absorption, has its disadvantages including long cycle times, contamination and a large equipment footprint. Alternative methods of hydrogen separation, such as electrochemical pumping, are a viable alternative to this separation dilemma due to …

Low Energy Recoil Simulations In Mgo, Linbo3, And Litao3 Using Ab Initio Molecular Dynamics, Benjamin Aaron Petersen

Doctoral Dissertations

Ab initio molecular dynamics (AIMD) was utilized to test a series of materials, MgO, LiNbO₃ , and LiTaO₃ , to determine defect structures produced due to low energy recoil events . The kinetic energy required to displace an atom from its lattice site, the threshold displacement energy, was calculated for an array of directions in each material, based on symmetry and complexity of the structure. MgO having a simple rock salt structure provided a model material for demonstrating computational techniques used later on LiTaO₃ and LiNbO₃ . The minimum values for displacing an atom were at …

An Exploration Of Basic Processes For Aqueous Electrochemical Production Of Hydrogen From Biomass Derived Molecules, Brian Fane

Doctoral Dissertations

Polymer electrolyte membrane fuel cells(PEMFCs) are energy conversion devices with significant potential. The factors preventing them from becoming widespread concern production and distribution of hydrogen. Developing an efficient hydrogen infrastructure with an approachable rollout plan is an essential step towards the future of fuel cells. Water electrolysis is limited by the thermodynamics of the process, which leads to high electrical consumption and significant materials challenges. Alternative methods for cleanly generating hydrogen while using a lower cell voltage are required. PEM based electrolyzers can operate with a "depolarized anode", whereby they become significantly less power hungry.

This thesis explores two techniques …

Design And Synthesis Of Analogs Of Myo-Inositol, Serine, And Cysteine To Enable Chemical Biology Studies, Tanei J. Ricks

Doctoral Dissertations

Phosphorylated myo-inositol compounds including inositol phosphates (InsPs) as well as the phosphatidylinositol polyphosphate lipids (PIP_ns) are critical biomolecules that regulate many of the most important biological processes and pathways. They are aberrant in many disease states due to their regulatory function. The same is true of the phospholipid phosphatidylserine (PS) which can serve as a marker to begin apoptosis. However, the full scope of activities of these structures is not clear, particularly since techniques that enable global detection and analysis of the production of these compounds spatially and temporally are lacking. With all of these obstacles in …

Nestle To Origami Coupling: A Nuclear Non-Proliferation Tool For Lwr Fuel Assembly Isotope Analysis, Margaret Alva Kurtts

Doctoral Dissertations

NESTLE to ORIGAMI coupling is a versatile nuclear modeling tool that allows researchers to directly observe the impact of operator induced changes on LWR assembly isotope production. The paper presents an experimental method by which to test the ability of an operator to manipulate the core neutron spectrum in order to produce higher quality plutonium for weapons use. The paper presents two plutonium production scenarios and evaluates their feasibility based on potential for detection and production capacity. Reactor modeling of a VVER-1000 uses NESTLE core simulation software. NESTLE outputs burnup and relative power information for all nodes in the core. …

Multiscale Modeling Approach To Understand Active Sites In Non-Conventional Catalyst Layers For Fuel Cell Applications, Diana Constanza Orozco Gallo

Doctoral Dissertations

Fuel cells development required stable, active and more abundant catalytic materials. Oxygen reduction reaction (ORR) is the key process to enhance better activity and reduce the fabrication costs. Pt-based has proven to be the best catalyst for ORR and greater efforts has been made in terms of reducing the Pt content in the electrodes, reduce electrode thickness and enhance better catalytic activities. To overcome many of the challenges present, the catalyst layer studies are the great importance in the fuel cell community. Understanding catalyst layer with new catalytic materials, and configurations requires the development of methodological approach to relate structure, …

Mechanical Behavior Of Pipeline Steels And An Al0.1cocrfeni High-Entropy Alloy, Bilin Chen

Doctoral Dissertations

This dissertation is composed of two parts. The first part focuses on the mechanical behavior study on pipelines steels. More specifically, the effect of hydrogen on the deformation behavior of the crack tip of an X52 pipeline steel specimen, and the overload effects on the fatigue crack growth of an x70 pipeline weld metal are discussed. For the second part of the dissertation, fatigue behavior of an Al0.1CoCrFeNi high-entropy alloy (HEA) is studied, and the influence of heat treatment is discussed.

The objectives of the first part of this proposed work are to (1) detect the influence of hydrogen on …

Determining 235u Enrichment Using A Dual-Energy Approach For Delayed Neutron Measurements, Angela Lynn Lousteau

Doctoral Dissertations

Bulk uranium items are often measured using active neutron interrogation systems to take advantage of the relatively high penetrability of neutrons, providing the ability to quickly and accurately measure uranium masses in large, dense configurations. Active techniques employ an external neutron source to induce fission in the uranium and subsequently measure emitted prompt fission or delayed neutrons. Unfortunately, the emitted neutrons from ²³⁵U [uranium-235] and ²³⁸U [uranium-238] are, for all practical purposes, indistinguishable; therefore, commonly used systems such as the Active Well Coincidence Counter, the ²⁵²Cf [californium-252] Shuffler, and other systems based on measurement of prompt or …

Wide-Area Control Schemes To Improve Small Signal Stability In Power Systems, Meimanat Mahmoudi

Doctoral Dissertations

One of the main concerns for the secure and reliable operation of power systems is the small signal stability problem. In the complex and highly interconnected structure of future power systems, relying solely on operator responses and conventional controls cannot assure reliability. Therefore, there is a need for advanced Wide-Area Control Schemes (WACS) that can automatically respond to degradation of reliability in the system.

The main objective of this dissertation is to address two key challenges regarding the design and implementation of wide-area control schemes for damping inter-area oscillations. First is the high communication cost associated with optimal centralized control …

Transport Of Water And Ions Through Single-Walled Armchair Carbon Nanotubes: A Molecular Dynamics Study, Michelle Patricia Aranha

Doctoral Dissertations

The narrow hydrophobic interior of a carbon nanotube (CNT) poses a barrier to the transport of water and ions, and yet, unexpectedly, numerous experimental and simulation studies have confirmed fast water transport rates comparable to those seen in biological aquaporin channels. These outstanding features of high water permeability and high solute rejection of even dissolved ions that would typically require a lot of energy for separation in commercial processes makes carbon nanotubes an exciting candidate for desalination membranes. Extending ion exclusion beyond simple mechanical sieving by the inclusion of electrostatics via added functionality to the nanotube bears promise to not …

Dynamic In Vivo Skeletal Feature Tracking Via Fluoroscopy Using A Human Gait Model, William Patrick Anderson

Doctoral Dissertations

The Tracking Fluoroscope System II, a mobile robotic fluoroscopy platform, developed and built at the University of Tennessee, Knoxville, presently employs a pattern matching algorithm in order to identify and track a marker placed upon a subject’s knee joint of interest. The purpose of this research is to generate a new tracking algorithm based around the human gait cycle for prediction and improving the overall accuracy of joint tracking.

This research centers around processing the acquired x-ray images of the desired knee joint obtained during standard clinical operation in order to identify and track directly through the acquired image. Due …

Methodology For An Advanced Risk Assessment Of Crud Induced Power Shift Using Coupled Multi-Physics Simulations And A Monte Carlo Scenario Analysis Of The Potential Financial Benefits, Travis Louis Lange

Doctoral Dissertations

Beginning in the 1970's, power uprates in nuclear power plants began to cause an operational problem called Crud Induced Power Shift (CIPS). Over decades, a method has been developed and refined that has allowed industry to effectively avoid CIPS. However, increasingly challenging economic environments have caused power plants to utilize more aggressive core designs. The problem of CIPS still looms over many reactors as a potential hazard requiring conservative measures. CIPS is due to complex physical and chemical interactions. Current industry methods use multiple single-physics simulations in their analyses. However, improved 3D multi-physics models of CIPS can provide a better …

Improvements To The Predictive Capability Of Fcm Fuel Performance Modeling, Daniel Philip Schappel

Doctoral Dissertations

A proposed fuel type for improved accident performance in LWRs (Light Water Reactors) involves TRISO (Tristructural-Isotropic) particles embedded in a NITE (Nano Infiltrated Eutectic) silicon carbide matrix. TRISO fuel particles contain a spherical fuel kernel of about 500 to in excess of 800 microns in diameter. The kernel and buffer layer are then coated with three isotropic layers consisting of a dense inner pyrolytic carbon (IPyC), a silicon carbide (SiC) layer, and an outer pyrolytic carbon (OPyC) layer. These layers are about 40 microns thick. The TRISO particle packing fraction in the NITE-SiC matrix is expected to be about 40 …

Intrusion Detection Of A Simulated Scada System Using A Data-Driven Modeling Approach, Brien Alen Jeffries

Doctoral Dissertations

Supervisory Control and Data Acquisition (SCADA) are large, geographically distributed systems that regulate help processes in industries such as nuclear power, transportation or manufacturing. SCADA is a combination of physical, sensing, and communications equipment that is used for monitoring, control and telemetry acquisition actions. Because SCADA often control the distribution of vital resources such as electricity and water, there is a need to protect these cyber-physical systems from those with possible malicious intent. To this end, an Intrusion Detection System (IDS) is utilized to monitor telemetry sources in order to detect unwanted activities and maintain overall system integrity.

This dissertation …

Crafting Nanostructured Neural Interfaces With Hydrogel Particles, Emily Ann Morin

Doctoral Dissertations

Central nervous system neural device functionality hinges on effective communication with surrounding neurons. This depends on both the permissiveness of the device material to promote neuron integration and the ability of the device to avoid a chronic inflammatory response. Here, a facile approach has been developed exploring the multiple functionalities of hydrogel particles to provide cues to impart neural integration for such materials. Three distinct, yet interconnected tasks were undertaken: investigating hydrogel particle-modified substrate neuron integration and central nervous system inflammatory response, investigating guided hydrogel particle adsorption, and investigating hydrogel particles as local reservoirs for counteracting adverse effects from oxidative …

Physical Information Incorporated Clustering Techniques And Their Applications In Transportation Information System, Yang Zhang

Doctoral Dissertations

Massive data from different sources are becoming available in transportation field, and spurring new research on utilizing these data to nurture new intelligent transportation information systems. Clustering algorithms are among the methods that are being applied to the domain but facing challenges. Classical clustering algorithms work fine with \point" based data, which are homogeneous and have no extra constraints. Data in transportation are sometimes involved with specific geometric shapes, have underlying constraints, and can be heterogeneous. There has been no clustering algorithm dedicated to these situations.

In this dissertation, we re-examine the mathematical foundation and underlying philosophy of hierarchical, density …

Flight Risk Management And Crew Reserve Optimization, Ying Zhang

Doctoral Dissertations

There are two key concerns in the development process of aviation. One is safety, and the other is cost. An airline running with high safety and low cost must be the most competitive one in the market. This work investigates two research efforts respectively relevant to these two concerns.

When building support of a real time Flight Risk Assessment and Mitigation System (FRAMS), a sequential multi-stage approach is developed. The whole risk management process is considered in order to improve the safety of each flight by integrating AHP and FTA technique to describe the framework of all levels of risks …

Fundamental Study And Development Of Tuned Active Flow Control Actuators, Brian A. Binkley

Doctoral Dissertations

A novel, multi-level, flow-control actuator was developed using piezoceramic materials. Several actuators were fabricated in various shapes and sizes to produce a variety of effects for flow control applications. The actuators were studied in a quiescent-air bench test to understand the vibrations produced by various actuator shapes. The actuator flow-control effect was studied experimentally with flat-plate and cavity configurations, and was studied numerically using moving boundary conditions and dynamic meshing. The disturbances produced by the actuator couple with the cavity flow field producing increased cavity tones, increased vorticity, and sustainment of large-scale vorticity downstream of the cavity. The combined actuation …

Development And Implementation Of A Forward Solution Hip Mathematical Model To Determine In Vivo Mechanics And Predict Hip Separation, Michael Thomas Lacour

Doctoral Dissertations

Osteoarthritis, signified by excessive wear of joint cartilage, is most common in hip, knee, and spinal joints [1]. Current treatment for extreme osteoarthritis is total joint arthroplasty, where the damaged bone and cartilage are removed and replaced by artificial bone representations separated by artificial cartilage representations. While this treatment does generally improve patient quality of life, current joint replacement systems unfortunately still yield atypically high forces, premature component wear, and abnormal kinematics compared to native joints [2] [3] [4] [5].

For total hip arthroplasty, one common complication is in vivo separation and dislocation of the femoral head within the acetabular …

Learning Multimodal Structures In Computer Vision, Ali Taalimi

Doctoral Dissertations

A phenomenon or event can be received from various kinds of detectors or under different conditions. Each such acquisition framework is a modality of the phenomenon. Due to the relation between the modalities of multimodal phenomena, a single modality cannot fully describe the event of interest. Since several modalities report on the same event introduces new challenges comparing to the case of exploiting each modality separately.

We are interested in designing new algorithmic tools to apply sensor fusion techniques in the particular signal representation of sparse coding which is a favorite methodology in signal processing, machine learning and statistics to …

Correlating Long-Term Lithium Ion Battery Performance With Solid Electrolyte Interphase (Sei) Layer Properties, Seong Jin An

Doctoral Dissertations

This study was conducted to understand effects of some of key factors (i.e., anode surface properties, formation cycling conditions, and electrolyte conditions) on solid electrolyte interphase (SEI) formation in lithium ion batteries (LIBs) and the battery cycle life. The SEI layer passivates electrode surfaces and prevents electron transfer and electrolyte diffusion through it while allowing lithium ion diffusion, which is essential for stable reversible capacities. It also influences initial capacity loss, self-discharge, cycle life, rate capability and safety. Thus, SEI layer formation and electrochemical stability are primary topics in LIB development. This research involves experiments and discussions on key factors …

First-Principles Study Of Point Defect Behavior At Interfaces And In-Plane Strain Fields, Jianqi Xi

Doctoral Dissertations

Interfaces in solid materials are the so-called boundaries, separating crystals with the same structure and chemistry but different orientations, e.g. grain boundaries (GBs), different stacking sequences, e.g. stacking faults (SFs), or crystals with different structures and/or chemistries as well as orientations, e.g. the interface between substrate and thin film. In this study, first-principles calculations are used to investigate the defect behavior at different interfaces and in-plane strain fields, such as stacking fault (SF) in silicon carbide (SiC), in-plane strain field near interfaces in potassium tantalate (KTaO₃), and grain boundary in ceria (CeO₂).

Results show that the …

Design And Implementation Of A Low‐Power Wireless Respiration Monitoring Sensor, Ifana Mahbub

Doctoral Dissertations

Wireless devices for monitoring of respiration activities can play a major role in advancing modern home-based health care applications. Existing methods for respiration monitoring require special algorithms and high precision filters to eliminate noise and other motion artifacts. These necessitate additional power consuming circuitry for further signal conditioning. This dissertation is particularly focused on a novel approach of respiration monitoring based on a PVDF-based pyroelectric transducer. Low-power, low-noise, and fully integrated charge amplifiers are designed to serve as the front-end amplifier of the sensor to efficiently convert the charge generated by the transducer into a proportional voltage signal. To transmit …

An Optimization Framework For Integrating Variable Capacity And Pavement Thickness Requirements In Highway Cost Allocation, Saurav Kumar Dubey

Doctoral Dissertations

The objective of Highway Cost Allocation (HCA) is to distribute or allocate in a fair and rational manner the cost of a transportation facility (either a highway or bridge) among all vehicle classes using it. The purpose of this dissertation is to study and enhance a model, known as the least-core model, to include both pavement thickness and traffic capacity requirements for all coalitions formed with a given group of vehicle classes. Considering vehicle classes as players and groups of vehicle classes as coalitions, it is possible to quantify the thickness and width of pavement needed to accommodate the vehicle …

Evaluation Of Increased Targeted Enforcement And Community-Based Outreach And Education Programs To Increase Nighttime Seatbelt Use In East Tennessee, Kwaku Frimpong Boakye

Doctoral Dissertations

According to the National Highway Traffic Safety Administration (NHTSA), motor vehicle crashes are the leading cause of death among people aged 1-54 in the United Sates. In 2015, the number of motor-vehicle deaths on U.S. roadways totaled 35,092, a 7% increase from 2014 (32,744). Though lower gas prices and increased vehicle mileage combined with risky driving behaviors (e.g. speeding, driving while texting) account for the increased fatality rate, seatbelt non-use has been a significant contributory factor. It is estimated that nearly half (48%) of passenger vehicle occupants involved in fatal crashes each year are unrestrained.

In a recent 2014 report …