Ab-initio calculation of optical properties of wurtzitic In_x Ga_1x N and In_x Al_1x N alloys including excitonic effects (open access)

Ab-initio calculation of optical properties of wurtzitic In_x Ga_1x N and In_x Al_1x N alloys including excitonic effects

None
Date: September 5, 2012
Creator: de Carvalho, L C; Schleife, A; Furthmueller, J & Bechstedt, F
Object Type: Article
System: The UNT Digital Library
Analysis of the Wake Field Effects in the PEP-II Storage Rings with Extremely High Currents (open access)

Analysis of the Wake Field Effects in the PEP-II Storage Rings with Extremely High Currents

None
Date: September 5, 2013
Creator: Novokhatski, A.; Seeman, J. & Sullivan, M.
Object Type: Article
System: The UNT Digital Library
Brute Force Modeling of the Kessler Syndrome (open access)

Brute Force Modeling of the Kessler Syndrome

None
Date: September 5, 2012
Creator: Nikolaev, S.; Phillion, D.; Springer, H. K.; deVries, W.; Jiang, M.; Pertica, A. et al.
Object Type: Article
System: The UNT Digital Library
Coexistence of the Alpha and Delta Phases in As-Cast Uranium-Rich U-Zr Alloys (open access)

Coexistence of the Alpha and Delta Phases in As-Cast Uranium-Rich U-Zr Alloys

None
Date: September 5, 2012
Creator: McKeown, J T; Irukuvarghula, S; Ahn, S; Wall, M; Hsiung, L L; McDeavitt, S et al.
Object Type: Article
System: The UNT Digital Library
Coherent X-Ray Seeding Source for Driving FELS (open access)

Coherent X-Ray Seeding Source for Driving FELS

None
Date: September 5, 2013
Creator: Novokhatski, A.; Decker, F. J.; Hettel, B.; Huang, Z.; Nuhn, H. D. & Sullivan, M.
Object Type: Article
System: The UNT Digital Library
Data Management Technology Survey and Recommendation (open access)

Data Management Technology Survey and Recommendation

None
Date: September 5, 2013
Creator: Epperly, T W & Agarwal, D
Object Type: Report
System: The UNT Digital Library
Data Package for Secondary Waste Form Down-Selection—Cast Stone (open access)

Data Package for Secondary Waste Form Down-Selection—Cast Stone

Available literature on Cast Stone and Saltstone was reviewed with an emphasis on determining how Cast Stone and related grout waste forms performed in relationship to various criteria that will be used to decide whether a specific type of waste form meets acceptance criteria for disposal in the Integrated Disposal Facility (IDF) at Hanford. After the critical review of the Cast Stone/Saltstone literature, we conclude that Cast Stone is a good candidate waste form for further consideration. Cast stone meets the target IDF acceptance criteria for compressive strength, no free liquids, TCLP leachate are below the UTS permissible concentrations and leach rates for Na and Tc-99 are suiteably low. The cost of starting ingredients and equipment necessary to generate Cast Stone waste forms with secondary waste streams are low and the Cast Stone dry blend formulation can be tailored to accommodate variations in liquid waste stream compositions. The database for Cast Stone short-term performance is quite extensive compared to the other three candidate waste solidification processes. The solidification of liquid wastes in Cast Stone is a mature process in comparison to the other three candidates. Successful production of Cast Stone or Saltstone has been demonstrated from lab-scale monoliths with volumes …
Date: September 5, 2011
Creator: Serne, R. Jeffrey & Westsik, Joseph H.
Object Type: Report
System: The UNT Digital Library
Design & Fabrication of a High-Voltage Photovoltaic Cell (open access)

Design & Fabrication of a High-Voltage Photovoltaic Cell

Silicon photovoltaic (PV) cells are alternative energy sources that are important in sustainable power generation. Currently, applications of PV cells are limited by the low output voltage and somewhat low efficiency of such devices. In light of this fact, this project investigates the possibility of fabricating high-voltage PV cells on float-zone silicon wafers having output voltages ranging from 50 V to 2000 V. Three designs with different geometries of diffusion layers were simulated and compared in terms of metal coverage, recombination, built-in potential, and conduction current density. One design was then chosen and optimized to be implemented in the final device design. The results of the simulation serve as a feasibility test for the design concept and provide supportive evidence of the effectiveness of silicon PV cells as high-voltage power supplies.
Date: September 5, 2012
Creator: Felder, Jennifer & /SLAC, /North Carolina State U.
Object Type: Report
System: The UNT Digital Library
Effect of SOFC Interconnect-Coating Interactions on Coating Properties and Performance (open access)

Effect of SOFC Interconnect-Coating Interactions on Coating Properties and Performance

The high operating temperature of solid oxide fuel cells (SOFCs) provides good fuel flexibility which expands potential applications, but also creates materials challenges. One such challenge is the interconnect material, which was the focus of this project. In particular, the objective of the project was to understand the interaction between the interconnect alloy and ceramic coatings which are needed to minimize chromium volatilization and the associated chromium poisoning of the SOFC cathode. This project focused on coatings based on manganese cobalt oxide spinel phases (Mn,Co)3O4, which have been shown to be effective as coatings for ferritic stainless steel alloys. Analysis of diffusion couples was used to develop a model to describe the interaction between (Mn,Co)3O4 and Cr2O3 in which a two-layer reaction zone is formed. Both layers form the spinel structure, but the concentration gradients at the interface appear like a two-phase boundary suggesting that a miscibility gap is present in the spinel solid solution. A high-chromium spinel layer forms in contact with Cr2O3 and grows by diffusion of manganese and cobalt from the coating material to the Cr2O3. The effect of coating composition, including the addition of dopants, was evaluated and indicated that the reaction rate could be decreased …
Date: September 5, 2012
Creator: Fergus, Jeffrey W.
Object Type: Report
System: The UNT Digital Library
Experimental Neutrino Physics: Final Report (open access)

Experimental Neutrino Physics: Final Report

Experimental studies of neutrino properties, with particular emphasis on neutrino oscillation, mass and mixing parameters. This research was pursued by means of underground detectors for reactor anti-neutrinos, measuring the flux and energy spectra of the neutrinos. More recent investigations have been aimed and developing detector technologies for a long-baseline neutrino experiment (LBNE) using a neutrino beam from Fermilab.
Date: September 5, 2012
Creator: Lane, Charles E. & Maricic, Jelena
Object Type: Report
System: The UNT Digital Library
DE-FG02-08ER64658 (OASIS) - Final Technical Report (open access)

DE-FG02-08ER64658 (OASIS) - Final Technical Report

Project OASIS (Operation of Advanced Structures, Interfaces and Sub-components for MEAs) was a 12 month project that ran from 1st September 2008 to 31st August 2009, and was managed by the Department of Energy Office of Science, Chicago Office, as Award No DE-FG02-08ER64658, with Johnson Matthey Fuel Cells Inc. as the sole contractor. The project was completed on schedule, with technical successes (details below) and payment of the full grant award made by DOE. The aim of the project was the development of membrane electrode assemblies (MEAs) for H2/air polymer electrolyte membrane (PEM) fuel cells that would give higher performance under hot/dry and dry operating conditions, ideally with no loss of performance under wet conditions. Reducing or eliminating the need for humidifying the incoming gases will allow significant system cost and size reduction for many fuel cell applications including automotive, stationary and back-up power, and portable systems. Portable systems are also of particular interest in military markets. In previous work Johnson Matthey Fuel Cells had developed very stable, corrosion-resistant catalysts suitable for resisting degradation by carbon corrosion in particular. These materials were applied within the OASIS project as they are considered necessary for systems such as automotive where multiple start-stop …
Date: September 5, 2013
Creator: Sharman, Jonathan
Object Type: Report
System: The UNT Digital Library
Fusion Simulation Program Definition. Final report (open access)

Fusion Simulation Program Definition. Final report

We have completed our contributions to the Fusion Simulation Program Definition Project. Our contributions were in the overall planning with concentration in the definition of the area of Software Integration and Support. We contributed to the planning of multiple meetings, and we contributed to multiple planning documents.
Date: September 5, 2012
Creator: Cary, John R.
Object Type: Report
System: The UNT Digital Library
High-Average Power Facilities (open access)

High-Average Power Facilities

There has been significant progress in the development of high-power facilities in recent years yet major challenges remain. The task of WG4 was to identify which facilities were capable of addressing the outstanding R&D issues presently preventing high-power operation. To this end, information from each of the facilities represented at the workshop was tabulated and the results are presented herein. A brief description of the major challenges is given, but the detailed elaboration can be found in the other three working group summaries.
Date: September 5, 2012
Creator: Dowell, David H. & Power, John G.
Object Type: Article
System: The UNT Digital Library
Improved resolution of hydrocarbon structures and constitutional isomers in complex mixtures using Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry (GC-VUV-MS) (Supplementary Info) (open access)

Improved resolution of hydrocarbon structures and constitutional isomers in complex mixtures using Gas Chromatography-Vacuum Ultraviolet-Mass Spectrometry (GC-VUV-MS) (Supplementary Info)

Understanding the composition of complex hydrocarbon mixtures is important for environmental studies in a variety of fields, but many prevalent compounds cannot be confidently identified using traditional gas chromatography-mass spectrometry (GC-MS) techniques. This work uses vacuum-ultraviolet (VUV) ionization to elucidate the structures of a traditionally"unresolved complex mixture" by separating components by GC retention time, tR, and mass-to-charge ratio, m/Q, which are used to determine carbon number, NC, and the number of rings and double bonds, NDBE. Constitutional isomers are resolved based on tR, enabling the most complete quantitative analysis to date of structural isomers in an environmentally-relevant hydrocarbon mixture. Unknown compounds are classified in this work by carbon number, degree of saturation, presence of rings, and degree of branching, providing structural constraints. The capabilities of this analysis are explored using diesel fuel, in which constitutional isomer distribution patterns are shown to be reproducible between carbon numbers and follow predictable rules. Nearly half of the aliphatic hydrocarbon mass is shown to be branched, suggesting branching is more important in diesel fuel than previously shown. The classification of unknown hydrocarbons and the resolution of constitutional isomers significantly improves resolution capabilities for any complex hydrocarbon mixture.
Date: September 5, 2011
Creator: Aerosol Dynamics Inc.,; Aerodyne Research, Inc.,; Tofwerk AG, Thun, Switzerland; Isaacman, Gabriel; Wilson, Kevin R.; Chan, Arthur W. H. et al.
Object Type: Article
System: The UNT Digital Library
Improving Conservation for First-Order System Least Squares Finite-Element Methods (open access)

Improving Conservation for First-Order System Least Squares Finite-Element Methods

None
Date: September 5, 2012
Creator: Adler, J H & Vassilevski, P S
Object Type: Article
System: The UNT Digital Library
Infrared Spectroscope for Electron Bunch-length Measurement: Heat Sensor Parameters Analysis (open access)

Infrared Spectroscope for Electron Bunch-length Measurement: Heat Sensor Parameters Analysis

The Linac Coherent Light Source (LCLS) is used for many experiments. Taking advantage of the free electron laser (FEL) process, scientists of various fields perform experiments of all kind. Some for example study protein folding; other experiments are more interested in the way electrons interact with the molecules before they are destroyed. These experiments among many others have very little information about the electrons x-ray produced by the FEL, except that the FEL is using bunches less than 10 femtoseconds long. To be able to interpret the data collected from those experiments, more accurate information is needed about the electron's bunch-length. Existing bunch length measurement techniques are not suitable for the measurement of such small time scales. Hence the need to design a device that will provide more precise information about the electron bunch length. This paper investigates the use of a pyreoelectric heat sensor that has a sensitivity of about 1.34 micro amps per watt for the single cell detector. Such sensitivity, added to the fact that the detector is an array sensor, makes the detector studied the primary candidate to be integrated to an infrared spectrometer designed to better measure the LCLS electron bunch length.
Date: September 5, 2012
Creator: Domgmo-Momo, Gilles & /SLAC, /Towson U.
Object Type: Report
System: The UNT Digital Library
LANL Virtual Center for Chemical Hydrogen Storage: Chemical Hydrogen Storage Using Ultra-high Surface Area Main Group Materials (open access)

LANL Virtual Center for Chemical Hydrogen Storage: Chemical Hydrogen Storage Using Ultra-high Surface Area Main Group Materials

The focus of the project was to design and synthesize light element compounds and nanomaterials that will reversibly store molecular hydrogen for hydrogen storage materials. The primary targets investigated during the last year were amine and hydrogen terminated silicon (Si) nanoparticles, Si alloyed with lighter elements (carbon (C) and boron (B)) and boron nanoparticles. The large surface area of nanoparticles should facilitate a favorable weight to volume ratio, while the low molecular weight elements such as B, nitrogen (N), and Si exist in a variety of inexpensive and readily available precursors. Furthermore, small NPs of Si are nontoxic and non-corrosive. Insights gained from these studies will be applied toward the design and synthesis of hydrogen storage materials that meet the DOE 2010 hydrogen storage targets: cost, hydrogen capacity and reversibility. Two primary routes were explored for the production of nanoparticles smaller than 10 nm in diameter. The first was the reduction of the elemental halides to achieve nanomaterials with chloride surface termination that could subsequently be replaced with amine or hydrogen. The second was the reaction of alkali metal Si or Si alloys with ammonium halides to produce hydrogen capped nanomaterials. These materials were characterized via X-ray powder diffraction, TEM, …
Date: September 5, 2010
Creator: Kauzlarich, Susan M.; Power, Phillip P.; Neiner, Doinita; Pickering, Alex; Rivard, Eric; Bobby Ellis, T. M. et al.
Object Type: Report
System: The UNT Digital Library
Lead Research and Development Activity for DOE's High Temperature, Low Relative Humidity Membrane Program (Topic 2) (open access)

Lead Research and Development Activity for DOE's High Temperature, Low Relative Humidity Membrane Program (Topic 2)

The Department of Energy’s High Temperature, Low Relative Humidity Membrane Program was begun in 2006 with the Florida Solar Energy Center (FSEC) as the lead organization. During the first three years of the program, FSEC was tasked with developing non-Nafion® proton exchange membranes with improved conductivity for fuel cells. Additionally, FSEC was responsible for developing protocols for the measurement of in-plane conductivity, providing conductivity measurements for the other funded teams, developing a method for through-plane conductivity and organizing and holding semiannual meetings of the High Temperature Membrane Working Group (HTMWG). The FSEC membrane research focused on the development of supported poly[perfluorosulfonic acid] (PFSA) – Teflon membranes and a hydrocarbon membrane, sulfonated poly(ether ether ketone). The fourth generation of the PFSA membrane (designated FSEC-4) came close to, but did not meet, the Go/No-Go milestone of 0.1 S/cm at 50% relative humidity at 120 °C. In-plane conductivity of membranes provided by the funded teams was measured and reported to the teams and DOE. Late in the third year of the program, DOE used this data and other factors to decide upon the teams to continue in the program. The teams that continued provided promising membranes to FSEC for development of membrane electrode …
Date: September 5, 2012
Creator: Fenton, James; Slattery, Darlene & Mohajeri, Nahid
Object Type: Report
System: The UNT Digital Library
Measurement of the D*(2010)+ meson width and the D*(2010)+ - D0 mass difference (open access)

Measurement of the D*(2010)+ meson width and the D*(2010)+ - D0 mass difference

None
Date: September 5, 2013
Creator: Lees, J. P.; Poireau, V.; Tisserand, V.; /Annecy, LAPP; Grauges, E.; /Barcelona U., ECM et al.
Object Type: Article
System: The UNT Digital Library
Measurement of the Mass of the D0 Meson (open access)

Measurement of the Mass of the D0 Meson

None
Date: September 5, 2013
Creator: unknown
Object Type: Article
System: The UNT Digital Library
Melting Thin Foils by Incident Relativistic Electron Bunch (open access)

Melting Thin Foils by Incident Relativistic Electron Bunch

None
Date: September 5, 2013
Creator: Stupakov, G.
Object Type: Report
System: The UNT Digital Library
Novel Six-Quark Hidden-Color Dibaryon States in QCD (open access)

Novel Six-Quark Hidden-Color Dibaryon States in QCD

None
Date: September 5, 2013
Creator: Bashkanov, M.; Brodsky, S.J. & Clement, H.
Object Type: Article
System: The UNT Digital Library
Performance of CID camera X-ray imagers at NIF in a harsh neutron environment (open access)

Performance of CID camera X-ray imagers at NIF in a harsh neutron environment

None
Date: September 5, 2013
Creator: Palmer, N. E.; Schneider, M. B.; Bell, P. M.; Piston, K.; Moody, J.; James, D. et al.
Object Type: Article
System: The UNT Digital Library
Precision Measurement of the e+e- \to K+K-(gamma) Cross Section with the Initial-State Radiation Method at BaBar (open access)

Precision Measurement of the e+e- \to K+K-(gamma) Cross Section with the Initial-State Radiation Method at BaBar

None
Date: September 5, 2013
Creator: Lees, J. P.; Poireau, V.; Tisserand, V.; /Annecy, LAPP; Grauges, E.; /Barcelona U., ECM et al.
Object Type: Article
System: The UNT Digital Library