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Articles 1 - 11 of 11
Full-Text Articles in Engineering
X-Ray Fluorescence For Quantification Of Lead And Strontium In Vivo, Aaron James Specht
X-Ray Fluorescence For Quantification Of Lead And Strontium In Vivo, Aaron James Specht
Open Access Dissertations
Lead (Pb) is a toxicant well known for its effects on almost every organ system in the body. Pb use in industry has declined since removal of Pb from gasoline, but many developing countries still have significant use of Pb. Exposure to Pb has been linked with diseases causing neurodegeneration and thus have lasting effects long after the initial exposure. Another metal, strontium (Sr), has been linked with bone disease in particular situations and shown to have uses in treating osteoporosis as a supplement. However, there are no studies of the effects of Sr using a meaningful biomarker. The most …
Nanoscale Phonon Thermal Conductivity Via Molecular Dynamics, Jonathan M. Dunn
Nanoscale Phonon Thermal Conductivity Via Molecular Dynamics, Jonathan M. Dunn
Open Access Theses
Molecular dynamics (MD) simulations provide a useful and simple means of calculating the nanoscale thermal properties of materials, which requires special analysis since the thermal properties of materials change when their dimensions reach the nanoscale. In this research, MD is used to investigate the nanoscale phonon thermal transport of materials that are attracting much interest in the areas of materials science and nuclear physics. In order to evaluate two distinct methods of calculating the thermal conductivity of materials using MD, the simulation methods are first applied to Si. Once an understanding of each simulation method is established, they are then …
Cosmic Ray Muons For Spent Nuclear Fuel Monitoring, Stylianos Chatzidakis
Cosmic Ray Muons For Spent Nuclear Fuel Monitoring, Stylianos Chatzidakis
Open Access Dissertations
There is a steady increase in the volume of spent nuclear fuel stored on-site (at reactor) as currently there is no permanent disposal option. No alternative disposal path is available and storage of spent nuclear fuel in dry storage containers is anticipated for the near future. In this dissertation, a capability to monitor spent nuclear fuel stored within dry casks using cosmic ray muons is developed. The motivation stems from the need to investigate whether the stored content agrees with facility declarations to allow proliferation detection and international treaty verification. Cosmic ray muons are charged particles generated naturally in the …
Well-Posedness And Convergence Of Cfd Two-Fluid Model For Bubbly Flows, Avinash Vaidheeswaran
Well-Posedness And Convergence Of Cfd Two-Fluid Model For Bubbly Flows, Avinash Vaidheeswaran
Open Access Dissertations
The current research is focused on developing a well-posed multidimensional CFD two-fluid model (TFM) for bubbly flows. Two-phase flows exhibit a wide range of local flow instabilities such as Kelvin-Helmholtz, Rayleigh-Taylor, plume and jet instabilities. They arise due to the density difference and/or the relative velocity between the two phases. A physically correct TFM is essential to model these instabilities. However, this is not the case with the TFMs in numerical codes, which can be shown to have complex eigenvalues due to incompleteness and hence are ill-posed as initial value problems. A common approach to regularize an incomplete TFM is …
Investigation And Modeling Of Uranium Polarization For The Electrorefining Of Scrap U-Mo Foils, Melissa Rose
Investigation And Modeling Of Uranium Polarization For The Electrorefining Of Scrap U-Mo Foils, Melissa Rose
Open Access Dissertations
A uranium molybdenum alloy fuel has been proposed to convert research and test reactors from highly enriched uranium to low enriched uranium to increase the proliferation resistance at such reactors. Pyroprocessing has been selected to recover uranium from the scrap produced in the manufacture of this novel fuel type. Electrorefining, the main separation process of pyroprocessing, is modeled through a novel approach using corrosion theory. To use corrosion theory, knowledge of uranium polarization and kinetic parameters such as Tafel constant, transfer coefficient and exchange current density are required. Uranium polarization was investigated at five temperatures and three scan rates in …
Hydrogen Loading System Development And Evaluation Of Tritiated Substrates To Optimize Performance In Tritium Based Betavoltaics, Thomas E. Adams
Hydrogen Loading System Development And Evaluation Of Tritiated Substrates To Optimize Performance In Tritium Based Betavoltaics, Thomas E. Adams
Open Access Dissertations
State-of-the-art hydrogen loading system onto thin metallic films based on differential pressure in calibrated chambers has been developed for conditions pressures and temperatures up to 69 bar and 500°C, respectively. Experiments on hydrogen loading on to palladium films of thickness 50 and 250 nm were conducted at pressure ranging from 0.2 bar to 10 bar at temperature 310°C. For first time film hydrogen loading was carried out at 1 bar and at room temperature which temperature. Beta flux exiting surface of metal tritide films has been modeled with MC-SET (Monte Carlo Simulation of Electron Trajectories in solids). Surface beta flux …
Experimental Study Of Droplet Capable Conductivity Probe, Yikuan Yan
Experimental Study Of Droplet Capable Conductivity Probe, Yikuan Yan
Open Access Theses
This research focus on experimentally studying the performance of the newly designed Droplet Capable Conductivity Probe (DCCP). ^ A literature review is performed to illustrate the development of current two-fluid model and interfacial area transport equation. Previous conductivity probe instrumentation is also reviewed. The limitations of current conductivity probe design are described and the necessity of developing DCCP is illustrated. ^ The concept of DCCP-2 and DCCP-4 are introduced and experiments are performed to benchmark the capability of DCCP-4.
Correlating Grain Size To Radiation Damage Tolerance Of Tungsten Materials Exposed To Relevant Fusion Conditions, Sean Robert Gonderman
Correlating Grain Size To Radiation Damage Tolerance Of Tungsten Materials Exposed To Relevant Fusion Conditions, Sean Robert Gonderman
Open Access Theses
Tungsten remains a leading candidate for plasma facing component (PFC) in future fusion devices. This is in large part due to its strong thermal and mechanical properties. The ITER project has already chosen to use an all tungsten divertor. Despite having a high melting temperature and low erosion rate, tungsten faces a large variety of issues when subject to fusion like conditions. These include embrittlement, melting, and extreme morphology change (growth of fuzz nanostructure). The work presented here investigates mechanisms that drive surface morphology change in tungsten materials exposed to fusion relevant plasmas. Specifically, tungsten materials of different grain sizes …
Drift-Flux Correlation Development For Two-Phase Flow In Rod Bundles, Collin M. Clark
Drift-Flux Correlation Development For Two-Phase Flow In Rod Bundles, Collin M. Clark
Open Access Theses
A rod bundle drift-flux correlation is developed with intended application across a wide range of two-phase flow conditions. Special consideration is made for fluid flow mechanisms at low liquid velocity and low pressure conditions. In these instances, gravitational forces from the density difference of the associated fluid phases are more significant. Secondary flow patterns may develop as a result and a drift-flux correlation would need to make appropriate adjustments. Earlier correlations may have increased error at these conditions if they have been formulated with respect to relatively higher pressures or flow rates. In the present work, area-average void fraction data …
Response Of Plasma Facing Components In Tokamaks Due To Intense Energy Deposition Using Particle-In-Cell(Pic) Methods, Filippo Genco
Response Of Plasma Facing Components In Tokamaks Due To Intense Energy Deposition Using Particle-In-Cell(Pic) Methods, Filippo Genco
Open Access Dissertations
Damage to plasma-facing components (PFC) due to various plasma instabilities is still a major concern for the successful development of fusion energy and represents a significant research obstacle in the community. It is of great importance to fully understand the behavior and lifetime expectancy of PFC under both low energy cycles during normal events and highly energetic events as disruptions, Edge-Localized Modes (ELM), Vertical Displacement Events (VDE), and Run-away electron (RE). The consequences of these high energetic dumps with energy fluxes ranging from 10 MJ/m2 up to 200 MJ/m2 applied in very short periods (0.1 to 5 ms) can be …
Development Of A Multiscale Atomistic Code To Investigate Self-Organized Pattern Formation Induced By Ion Irradiation, Zhangcan Yang
Development Of A Multiscale Atomistic Code To Investigate Self-Organized Pattern Formation Induced By Ion Irradiation, Zhangcan Yang
Open Access Dissertations
Various self-organized patterns including ripples and quantum dots can be induced by ion beam sputtering (IBS). For the past decades, the understanding of such phenomenon has been mainly relied on the Bradley-Harper theory that attributes the formation of self-organized patterns to the interplay between roughening by curvature dependence of erosion and smoothening by surface diffusion. Recently, the development of the crater function theory has overturned this erosion-based paradigm to a redistribution-based paradigm. The theory has proved that erosion is irrelevant and negligible in the pattern formation at low and intermediate incidence angles. Despite the success, there are still some questions …