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Full-Text Articles in Physical Sciences and Mathematics

Validation Of Weak Form Thermal Analysis Algorithms Supporting Thermal Signature Generation, Elton Lewis Freeman Dec 2012

Validation Of Weak Form Thermal Analysis Algorithms Supporting Thermal Signature Generation, Elton Lewis Freeman

Masters Theses

Extremization of a weak form for the continuum energy conservation principle differential equation naturally implements fluid convection and radiation as flux Robin boundary conditions associated with unsteady heat transfer. Combining a spatial semi-discretization via finite element trial space basis functions with time-accurate integration generates a totally node-based algebraic statement for computing. Closure for gray body radiation is a newly derived node-based radiosity formulation generating piecewise discontinuous solutions, while that for natural-forced-mixed convection heat transfer is extracted from the literature. Algorithm performance, mathematically predicted by asymptotic convergence theory, is subsequently validated with data obtained in 24 hour diurnal field experiments for …


Evaluation Of Tagging Techniques Gamma-Decay Probabilities Using The Surrogate Method, Timothy Lee Reed Dec 2012

Evaluation Of Tagging Techniques Gamma-Decay Probabilities Using The Surrogate Method, Timothy Lee Reed

Masters Theses

A detailed analysis of the statistical and discrete [gamma]-decay tagging techniques was conducted using the absolute surrogate and surrogate ratio method (SRM) to obtain the 92Mo(n,[gamma]) cross section in an equivalent neutron energy range of 80 to 880 keV. Excited 93Mo and 95Mo nuclei were populated using (d,p) reactions on 92Mo and 94Mo targets, respectively. The absolute surrogate 92Mo(n,[gamma]) cross sections disagreed with evaluated neutron capture cross section data by as much as a factor of 4 using the statistical tagging approach, whereas the discrete [gamma]-decay tag absolute surrogate cross section disagreed with the evaluated neutron capture cross section by …


Testing A Novel Technique To Improve Aluminum-26 Accelerator Mass Spectrometry Measurements For Earth Science Applications, Meghan Sarah Janzen Dec 2012

Testing A Novel Technique To Improve Aluminum-26 Accelerator Mass Spectrometry Measurements For Earth Science Applications, Meghan Sarah Janzen

Masters Theses

The measurement of cosmogenic 26Al [aluminum-26] in geological samples by accelerator mass spectrometry (AMS) is typically conducted on Al2O3 [aluminum oxide] targets. However, Al2O3 is not an ideal source material because it does not form a prolific beam of Al- [negative atomic aluminum ions] required for measuring low-levels of 26Al. This thesis presents the performance of AlN [aluminum nitride], AlF3 [aluminum fluoride] and mixed AlN + Al2O3 as novel alternative source materials for the analysis of 26Al. A negative ion cesium sputtering source at the Holifield …


Physics Faculty Use Of Example Solutions In Teaching Introductory Physics, William O. Mamudi Dec 2012

Physics Faculty Use Of Example Solutions In Teaching Introductory Physics, William O. Mamudi

Masters Theses

This study investigates how physics faculty perceive and use features of example problem solutions. Thirty physics instructors from diverse institutions participated in semi-structured interviews. In addition to open-ended questions, three example problem solution artifacts were used to focus on specific solution features. Data were analyzed to identify instructors’ goals for the use of example solutions and whether their goals were consistent with the solution features that they valued and used. The study concludes that many faculty have three major goals: keeping students cognitively involved, helping students become better problem solvers, and supporting students in learning physics. The study also found …


Higher-Order Corrections In Effective Theory Of Deformed Nuclei, Jialin Zhang Aug 2012

Higher-Order Corrections In Effective Theory Of Deformed Nuclei, Jialin Zhang

Masters Theses

The low-energy excitation bands of open-shell heavy nuclei have been accounted for by collective motion of the constituting nucleons. Macroscopically, heavy nuclei can be looked upon as deformed rotors undergoing surface vibration and rotation. Traditionally, deformed nuclei are described within the Bohr-Mottelson geometric model or the interacting boson model. An effective theory that exploits spontaneous symmetry breaking has recently been developed for axially deformed nuclei. It describes the rotational and vibrational degrees of freedom in terms of Nambu-Goldstone bosons and quadrupole phonons respectively, with a power counting based on their different energy scales. A systematic way to construct the rotationally …


The Dissemination And Effective Use Of Physics Education Research In Undergraduate Instruction, Trevor Stefanick Aug 2012

The Dissemination And Effective Use Of Physics Education Research In Undergraduate Instruction, Trevor Stefanick

Masters Theses

Based on the results of a national survey of physics faculty, a set of interviews was conducted of 70 physics faculty from a diverse set of institutions. The interviews included questions about the dissemination and effective use of curricula and instructional strategies based on Physics Education Research (PER), focused to obtain recommendations to the PER community that might help to spread the use of these PER-based materials. Approximately half of the interviews (those with faculty who indicated knowledge about or use of Peer Instruction) have been previously analyzed. This project is the analysis of the 38 interviews that were conducted …


A High-Energy Neutron Flux Spectra Measurement Method For The Spallation Neutron Source, Nicholas Patrick Luciano May 2012

A High-Energy Neutron Flux Spectra Measurement Method For The Spallation Neutron Source, Nicholas Patrick Luciano

Masters Theses

The goal of this work was to develop a foil activation method to measure high-energy (∼1-100 MeV) neutron flux spectra at the Spallation Neutron Source by researching the scientific literature, assembling an experimental apparatus, performing experiments, analyzing the results, and refining the technique based on experience. The primary motivation for this work is to provide a benchmark for the neutron source term used in target station and shielding simulations Two sets of foil irradiations were performed, one at the ARCS beamline and one at the POWGEN beamline. The gamma radiation of the foil activation products was measured with a high …


The Variation Of Hydrogen Concentration In Ni/Mgh Thin Film With Temperature, Rex Nyadaufe Taibu Apr 2012

The Variation Of Hydrogen Concentration In Ni/Mgh Thin Film With Temperature, Rex Nyadaufe Taibu

Masters Theses

The thermal stability of Ni/MgH thin film deposited on Si substrate by Unbalanced Magnetron Physical Vapor Deposition has been investigated using Ion Beam analysis (DBA) techniques. Rutherford Backscattering Spectrometry (RBS) and Non-Rutherford Backscattering Spectrometry (NRBS) have been used to find the composition of Magnesium, Nickel and Oxygen. Elastic Recoil Detection Analysis (ERDA) has been used to determine the concentration of hydrogen at each level of heating. Heating was done in the Ultra High Vacuum (UHV) environment using a non gassy button heater. Ni/MgH sample had lost most of its hydrogen after being heated to a temperature of about 125°C in …


An Application Of Optical Tweezers, Patrick W. Swanson Jan 2012

An Application Of Optical Tweezers, Patrick W. Swanson

Masters Theses

No abstract provided.