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Snowflake divertor configuration studies for NSTX-Upgrade

Description: Snowflake divertor experiments in NSTX provide basis for PMI development toward NSTX-Upgrade. Snowflake configuration formation was followed by radiative detachment. Significant reduction of steady-state divertor heat flux observed in snowflake divertor. Impulsive heat loads due to Type I ELMs are partially mitigated in snowflake divertor. Magnetic control of snowflake divertor configuration is being developed. Plasma material interface development is critical for NSTX-U success. Four divertor … more
Date: November 12, 2011
Creator: Soukhanovskii, V A
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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High-Pressure Evolution of Fe2O3 Electronic Structure Revealed by X-ray Absorption

Description: We report the first high pressure measurement of the Fe K-edge in hematite (Fe{sub 2}O{sub 3}) by X-ray absorption spectroscopy in partial fluorescence yield geometry. The pressure-induced evolution of the electronic structure as Fe{sub 2}O{sub 3} transforms from a high-spin insulator to a low-spin metal is reflected in the x-ray absorption pre-edge. The crystal field splitting energy was found to increase monotonically with pressure up to 48 GPa, above which a series of phase transitions occur… more
Date: August 12, 2011
Creator: Kao, Chi-Chang
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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SUSTAINABLE REMEDIATION SOFTWARE TOOL EXERCISE AND EVALUATION

Description: The goal of this study was to examine two different software tools designed to account for the environmental impacts of remediation projects. Three case studies from the Savannah River Site (SRS) near Aiken, SC were used to exercise SiteWise (SW) and Sustainable Remediation Tool (SRT) by including both traditional and novel remediation techniques, contaminants, and contaminated media. This study combined retrospective analysis of implemented projects with prospective analysis of options that we… more
Date: May 12, 2011
Creator: Kohn, J.; Nichols, R. & Looney, B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The Influence of the Linker Geometry in Bis(3-hydroxy-N-methyl-pyridin-2-one) Ligands on Solution-Phase Uranyl Affinity

Description: Seven water-soluble, tetradentate bis(3-hydroxy-N-methyl-pyridin-2-one) (bis-Me-3,2-HOPO) ligands were synthesized that vary only in linker geometry and rigidity. Solution phase thermodynamic measurements were conducted between pH 1.6 and pH 9.0 to determine the effects of these variations on proton and uranyl cation affinity. Proton affinity decreases by introduction of the solubilizing triethylene glycol group as compared to un-substituted reference ligands. Uranyl affinity was found to follo… more
Date: August 12, 2010
Creator: Szigethy, Geza & Raymond, Kenneth
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Rational Ligand Design for U(VI) and Pu(IV)

Description: Nuclear power is an attractive alternative to hydrocarbon-based energy production at a time when moving away from carbon-producing processes is widely accepted as a significant developmental need. Hence, the radioactive actinide power sources for this industry are necessarily becoming more widespread, which is accompanied by the increased risk of exposure to both biological and environmental systems. This, in turn, requires the development of technology designed to remove such radioactive threa… more
Date: August 12, 2009
Creator: Szigethy, Geza
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Non-Proliferative, Thorium-Based, Core and Fuel Cycle for Pressurized Water Reactors

Description: Two of the major barriers to the expansion of worldwide adoption of nuclear power are related to proliferation potential of the nuclear fuel cycle and issues associated with the final disposal of spent fuel. The Radkowsky Thorium Fuel (RTF) concept proposed by Professor A. Radkowsky offers a partial solution to these problems. The main idea of the concept is the utilization of the seed-blanket unit (SBU) fuel assembly geometry which is a direct replacement for a 'conventional' assembly in eithe… more
Date: July 12, 2009
Creator: M., Todosow; M., Todosow & Raitses, G. (BNL) Galperin, A. (Ben Gurion University)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Colloidally Synthesized Monodisperse Rh Nanoparticles Supported on SBA-15 for Size- and Pretreatment-Dependent Studies of CO Oxidation

Description: A particle size dependence for CO oxidation over rhodium nanoparticles of 1.9-11.3 nm has been investigated and determined to be modified by the existence of the capping agent poly(vinylpyrrolidone) (PVP). The particles were prepared using a polyol reduction procedure with PVP as the capping agent. The Rh nanoparticles were subsequently supported on SBA-15 during hydrothermal synthesis to produce Rh/SBA-15 supported catalysts for size-dependent catalytic studies. CO oxidation by O{sub 2} at 40 … more
Date: February 12, 2009
Creator: Grass, Michael E.; Joo, Sang Hoon & Somorjai, Gabor A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Index Theorem for Topological Excitations on R^3 \times S^1 and Chern-Simons Theory

Description: We derive an index theorem for the Dirac operator in the background of various topological excitations on an R{sup 3} x S{sup 1} geometry. The index theorem provides more refined data than the APS index for an instanton on R{sup 4} and reproduces it in decompactification limit. In the R{sup 3} limit, it reduces to the Callias index theorem. The index is expressed in terms of topological charge and the {eta}-invariant associated with the boundary Dirac operator. Neither topological charge nor {e… more
Date: December 12, 2008
Creator: Poppitz, Erich & Unsal, Mithat
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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FRACTURE ENHANCED SOIL VAPOR EXTRACTION TECHNOLOGY DEMONSTRATION AT THE A-014 OUTFALL

Description: Data collected during this study show that the performance of hydraulically fractured wells (with respect to mass removal rates) may tend to decrease with time following precipitation events. These effects are due to temporary increases in water saturation in the formation within the vicinity of the fractures, therefore, the wells should tend to rebound during subsequent dry periods. The data available for fractured well versus conventional well performance (with respect to flow rate versus vac… more
Date: March 12, 2008
Creator: Riha, B; Warren Hyde, W & Richard Hall (NOEMAIL), R
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Surprising Coordination Geometry Differences in Ce(IV)- and Pu(IV)-Maltol Complexes

Description: As part of a study to characterize the detailed coordination behavior of Pu(IV), single crystal X-ray diffraction structures have been determined for Pu(IV) and Ce(IV) complexes with the naturally-occurring ligand maltol (3-hydroxy-2-methyl-pyran-4-one) and its derivative bromomaltol (5-bromo-3-hydroxy-2-methyl-pyran-4-one). Although Ce(IV) is generally accepted as a structural analog for Pu(IV), and the maltol complexes of these two metals are isostructural, the corresponding bromomaltol compl… more
Date: February 12, 2008
Creator: Laboratory, Lawrence Berkeley National; Raymond, Kenneth; Szigethy, Geza; Xu, Jide; Gorden, Anne E.V.; Teat, Simon J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Quantum Monte-Carlo Study of Electron Correlation in Heterostructure Quantum Dots

Description: The goal of this project is to study electron correlation in a confined geometry (quantum dots) within the two-dimensional quantum well in the sandwiches of two semiconductor materials. For these systems one is able to tune the electronic properties by controlling the size and the electron number, creating tremendous potential for novel applications. Much effort in this emerging field has been devoted to producing entangled states that are required for quantum information processing. At the sam… more
Date: November 12, 2006
Creator: Chou, Mei-Yin
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Magnetic Field Line Tracing Calculations for Conceptual PFC Design in the National Compact Stellarator Experiment

Description: The National Compact Stellarator Experiment (NCSX) is a three-field period compact stellarator presently in the construction phase at Princeton, NJ. The design parameters of the device are major radius R=1.4m, average minor radius <a> = 0.32m, 1.2 {le} toroidal field (B{sub t}) {le} 1.7 T, and auxiliary input power up to 12 MW with neutral beams and radio-frequency heating. The NCSX average aspect ratio <R/a> of 4.4 lies well below present stellarator experiments and designs, enabli… more
Date: June 12, 2006
Creator: Maingi, R; Kaiser, T; Hill, D N; Lyon, J F; Monticello, D & Zarnstorff, M C
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Program Pu Futures 2006

Description: The coordination chemistry of plutonium remains relatively unexplored. Thus, the fundamental coordination chemistry of plutonium is being studied using simple multi-dentate ligands with the intention that the information gleaned from these studies may be used in the future to develop plutonium-specific sequestering agents. Towards this goal, hard Lewis-base donors are used as model ligands. Maltol, an inexpensive natural product used in the commercial food industry, is an ideal ligand because i… more
Date: June 12, 2006
Creator: Fluss, M
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Angular dependence of dissociative electron attachment topolyatomic molecules: application to the 2B1 metastable state of the H2Oand H2S anions

Description: The angular dependence of dissociative electron attachment (DEA) to polyatomic targets is formulated in the local complex potential model, under the assumption that the axial recoil approximation describes the dissociation dynamics. An additional approximation, which is found to be valid in the case of H2O but not in the case of H2S, makes it possible to describe the angular dependence of DEA solely from an analysis of the fixed-nuclei entrance amplitude, without carrying out nuclear dynamics c… more
Date: January 12, 2006
Creator: Haxton, Daniel J.; McCurdy, C. William & Rescigno, Thomas N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

As-Built Modeling of Ojbects for Performance Assessment

Description: The goal of ''as-built'' computational modeling is to incorporate the most representative geometry and material information for an (fabricated or legacy) object into simulations. While most engineering finite element simulations are based on an object's idealized ''as-designed'' configuration with information obtained from technical drawings or computer-aided design models, ''as-built'' modeling uses nondestructive characterization and metrology techniques to provide the feature information. By… more
Date: September 12, 2005
Creator: Kokko, E J; Martz, H E; Chinn, D J; Childs, H. R.; Jackson, J A; Chambers, D H et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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W-Band Sheet Beam Klystron Simulation

Description: With the development of ever higher energy particle accelerators comes the need for compactness and high gradient, which in turn require very high frequency high power rf sources. Recent development work in W-band accelerating techniques has spurred the development of a high-power W-band source. Axisymmetric sources suffer from fundamental power output limitations (P{sub sat} {approx} {lambda}{sup 2}) brought on by the conflicting requirements of small beam sizes and high beam current. The shee… more
Date: September 12, 2005
Creator: Colby, E. R.; Caryotakis, G.; Fowkes, W. R. & Smithe, D. N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

First Results with the Prototype Detectors of the Si/W ECAL

Description: Measurements on the prototype silicon sensors for use with an electromagnetic calorimeter with tungsten absorber are reported. The prototype sensors are based on a hexagonal geometry that optimally utilizes the space available on 6 inch silicon wafers. The sensors are segmented into approximately 750 5mm hexagonal pixels, which are connected to a bump-bonding array located at the center of the sensors. We report on those properties of the sensors that are important for linear collider applicati… more
Date: July 12, 2005
Creator: Strom, D; Frey, R.; Breidenbach, M.; Deng, J.; Freytag, D.; Graf, N. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A Study of Electrochemical Reduction of Ethylene and Propylene Carbonate Electrolytes on Graphite Using ATR-FTIR Spectroscopy

Description: We present results testing the hypothesis that there is a different reaction pathway for the electrochemical reduction of PC versus EC-based electrolytes at graphite electrodes with LiPF6 as the salt in common. We examined the reduction products formed using ex-situ Fourier Transform Infrared (FTIR) spectroscopy in attenuated total reflection (ATR) geometry. The results show the pathway for reduction of PC leads nearly entirely to lithium carbonate as the solid product (and presumably ethylene … more
Date: May 12, 2005
Creator: Zhuang, Guorong V.; Yang, Hui; Blizanac, Berislav & Ross, Philip N., Jr.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Implosion Hydrodynamics of Fast Ignition Targets

Description: The fast ignition (FI) concept requires the generation of a compact, dense, pure fuel mass accessible to an external ignition source. The current baseline FI target is a shell fitted with a reentrant cone extending to near its center. Conventional direct or indirect drive collapses the shell near the tip of the cone and then an ultra-intense laser pulse focused to the inside cone tip generates high-energy electrons to ignite the dense fuel. We have theoretically and experimentally investigated … more
Date: November 12, 2004
Creator: Stephens, R. B.; Hatchett, S. P.; Tabak, M.; Stoeckl, C.; Sangster, T. C.; Petrasso, R. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Simulation of Spheromak Evolution and Energy Confinement

Description: Simulation results are presented that illustrate the formation and decay of a spheromak plasma driven by a coaxial electrostatic plasma gun, and that model the energy confinement of the plasma. The physics of magnetic reconnection during spheromak formation is also illuminated. The simulations are performed with the three-dimensional, time-dependent, resistive magnetohydrodynamic NIMROD code. The dimensional, simulation results are compared to data from the SSPX spheromak experiment at the Lawr… more
Date: November 12, 2004
Creator: Cohen, B; Hooper, E; Cohen, R; Hill, D; McLean, H; Wood, R et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Density Effects on Tokamak Edge Turbulence and Transport with Magnetic X-points

Description: Results are presented from the 3D electromagnetic turbulence code BOUT, the 2D transport code UEDGE, and theoretical analysis of boundary turbulence and transport in a real divertor-plasma geometry and its relationship to the density limit. Key results include: (1) a transition of the boundary turbulence from resistive X-point to resistive-ballooning as a critical plasma density is exceeded; (2) formation of an X-point MARFE in 2D UEDGE transport simulations for increasing outboard radial trans… more
Date: October 12, 2004
Creator: Xu, X. Q.; Cohen, R. H.; Nevins, W. M.; Rognlien, T. D.; Ryutov, D. D.; Umansky, M. V. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Recent enhancements to the MARS15 code

Description: The MARS code is under continuous development and has recently undergone substantial improvements that further increase its reliability and predictive power in numerous shielding, accelerator, detector and space applications. The major developments and new features of the MARS15 (2004) version described in this paper concern an extended list of elementary particles and arbitrary heavy ions and their interaction cross-sections, inclusive and exclusive nuclear event generators, module for modelin… more
Date: May 12, 2004
Creator: al., Nikolai V. Mokhov et
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Comparison of CFD Natural Convection and Conduction-only Models for Heat Transfer in the Yucca Mountain Project Drifts

Description: Yucca Mountain, Nevada has been designated as the nation's high-level radioactive waste repository and the U.S. Department of Energy has been approved to apply to the U.S. Nuclear Regulatory Commission for a license to construct a repository. Heat transfer in the Yucca Mountain Project (YMP) drift enclosures is an important aspect of repository waste emplacement. Canisters containing radioactive waste are to be emplaced in tunnels drilled 500 m below the ground surface. After repository closure… more
Date: February 12, 2004
Creator: Hadgu, T.; Webb, S. & Itamura, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A Microbeam Bending Method for Studying Stress-Strain Relations for Metal Thin Films on Silicon Substrates

Description: We have developed a microbeam bending technique for determining elastic-plastic, stress-strain relations for thin metal films on silicon substrates. The method is similar to previous microbeam bending techniques, except that triangular silicon microbeams are used in place of rectangular beams. The triangular beam has the advantage that the entire film on the top surface of the beam is subjected to a uniform state of plane strain as the beam is deflected, unlike the standard rectangular geometry… more
Date: February 12, 2004
Creator: Florando, J. N. & Nix, W. D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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