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Force10 P10 Evaluation
The lack of an acceptable intrusion monitoring solution limits the deployment of 10GE (10 Gigabit-per-second Ethernet) technology across the LLNL's unclassified network infrastructure. The desire to operate at 10GE motivates us to evaluate the functionality and performance of a 10GE intrusion monitoring solution, the Force10 P10.
Date:
June 8, 2007
Creator:
Allen, J.; Goldstone, R.; Instenes, S. & Lawver, B.
Object Type:
Report
System:
The UNT Digital Library
Power Electronic Thermal System Performance and Integration
Thermal control is a critical factor in power electronics equipment. NREL aims to integrate and improve thermal system performance in power electronics.
Date:
November 8, 2007
Creator:
Bennion, K.
Object Type:
Presentation
System:
The UNT Digital Library
Ion Beam Induced Surface Modulations from Nano to Pico: Optimizing Deposition During Erosion and Erosion During Deposition.
Ion beams of sufficient energy to erode a surface can lead to surface modulations that depend on the ion beam, the material surface it impinges, and extrinsic parameters such as temperature and geometric boundary conditions. Focused Ion Beam technology both enables site-specific placement of these modulations and expedites research through fast, high dose and small efficient use of material. The DualBeam (FIB/SEM) enables in situ metrology, with movies observing ripple formation, wave motion, and the influence of line defects. Nanostructures (ripples of >400nm wavelength to dots spaced <40nm) naturally grow from atomically flat surfaces during erosion, however, a steady state size may or may not be achieved as a consequence of numerous controlled parameters: temperature, angle, energy, crystallography. Geometric factors, which can be easily invoked using a FIB, enable a controlled component of deposition (and/or redeposition) to occur during erosion, and conversely allow a component of etching to be incurred during (ion-beam assisted) deposition. High angles of ion beam inclination commonly lead to 'rougher' surfaces, however, the extreme case of 90.0{sup o} etching enables deposition of organized structures 1000 times smaller than the aforementioned, video-recorded nanostructures. Orientation and position of these picostructures (naturally quantized by their atomic spacings) may be …
Date:
November 8, 2007
Creator:
MoberlyChan, W J & Schalek, R
Object Type:
Article
System:
The UNT Digital Library
Modeling EERE Deployment Programs
The purpose of this report is to compile information and conclusions gathered as part of three separate tasks undertaken as part of the overall project, “Modeling EERE Deployment Programs,” sponsored by the Planning, Analysis, and Evaluation office within the Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE). The purpose of the project was to identify and characterize the modeling of deployment programs within the EERE Technology Development (TD) programs, address improvements to modeling in the near term, and note gaps in knowledge where future research is needed.
Date:
November 8, 2007
Creator:
Cort, Katherine A.; Hostick, Donna J.; Belzer, David B. & Livingston, Olga V.
Object Type:
Report
System:
The UNT Digital Library
Dislocation nucleation in bcc Ta single crystals studied by nanoindentation
The study of dislocation nucleation in closed-packed metals by nanoindentation has recently attracted much interest. Here, we address the peculiarities of the incipient plasticity in body centered cubic (bcc) metals using low index Ta single-crystals as a model system. The combination of nanoindentation with high-resolution atomic force microscopy provides us with experimental atomic-scale information on the process of dislocation nucleation and multiplication. Our results reveal a unique deformation behavior of bcc Ta at the onset of plasticity which is distinctly different from that of closed-packed metals. Most noticeable, we observe only one rather than a sequence of discontinuities in the load-displacement curves. This and other differences are discussed in context of the characteristic plastic deformation behavior of bcc metals.
Date:
August 8, 2007
Creator:
Biener, M M; Biener, J; Hodge, A M & Hamza, A V
Object Type:
Article
System:
The UNT Digital Library
The NOvA Technical Design Report
Technical Design Report (TDR) describes the preliminary design of the NOvA accelerator upgrades, NOvA detectors, detector halls and detector sites. Compared to the March 2006 and November 2006 NOvA Conceptual Design Reports (CDR), critical value engineering studies have been completed and the alternatives still active in the CDR have been narrowed to achieve a preliminary technical design ready for a Critical Decision 2 review. Many aspects of NOvA described this TDR are complete to a level far beyond a preliminary design. In particular, the access road to the NOvA Far Detector site in Minnesota has an advanced technical design at a level appropriate for a Critical Decision 3a review. Several components of the accelerator upgrade and new neutrino detectors also have advanced technical designs appropriate for a Critical Decision 3a review. Chapter 1 is an Executive Summary with a short description of the NOvA project. Chapter 2 describes how the Fermilab NuMI beam will provide a narrow band beam of neutrinos for NOvA. Chapter 3 gives an updated overview of the scientific basis for the NOvA experiment, focusing on the primary goal to extend the search for {nu}{sub {mu}} {yields} {nu}{sub e} oscillations and measure the sin{sup 2}(2{theta}{sub 13}) parameter. …
Date:
October 8, 2007
Creator:
Ayres, D. S.; Drake, G. R.; Goodman, M. C.; Grudzinski, J. J.; Guarino, V. J.; Talaga, R. L. et al.
Object Type:
Report
System:
The UNT Digital Library
Amplification of an ultra short pulse laser by stimulated Raman scattering of a 1 ns pulse in a low density plasma
Experiments are described in which a 1mJ, 1ps, 1200 nm seed laser beam is amplified by interaction with an intersecting 350 J, 1ns, 1054 nm pump beam in a low density (1 x 10{sup 19}/cm{sup 3}) plasma. The transmission of the seed beam is observed to be enhanced by > {approx} 25 x when the plasma is near the resonant density for stimulated Raman scattering (SRS), compared to measured transmissions at wavelengths just below the resonant value. The amplification is observed to increase rapidly with increases in both pump intensity and plasma density.
Date:
October 8, 2007
Creator:
Kirkwood, R. K.; Dewald, E.; Niemann, C.; Meezan, N.; Wilks, S. C.; Price, D. W. et al.
Object Type:
Article
System:
The UNT Digital Library
Using IOR to analyze the I/O Performance for HPC Platforms
The HPC community is preparing to deploy petaflop-scale computing platforms that may include hundreds of thousands to millions of computational cores over the next 3 years. Such explosive growth in concurrency creates daunting challenges for the design and implementation of the I/O system. In this work, we first analyzed the I/O practices and requirements of current HPC applications and used them as criteria to select a subset of microbenchmarks that reflect the workload requirements. Our analysis led to selection of IOR, an I/O benchmark developed by LLNL for the ASCI Purple procurement, as our tool to study the I/O performance on two HPC platforms. We selected parameterizations for IOR that match the requirements of key I/O intensive applications to assess its fidelity in reproducing their performance characteristics.
Date:
June 8, 2007
Creator:
Shan, Hongzhang & Shalf, John
Object Type:
Article
System:
The UNT Digital Library
A low-energy linear oxygen plasma source
A new version of a Constricted Plasma Source is described,characterized by all metal-ceramic construction, a linear slit exit of180 mm length, and cw-operation (typically 50 kHz) at an average power of1.5 kW. The plasma source is here operated with oxygen gas, producingstreaming plasma that contains mainly positive molecular and atomic ions,and to a much lesser degree, negative ions. The maximum total ion currentobtained was about 0.5 A. The fraction of atomic ions reached more than10 percent of all ions when the flow rate was less then 10 sccm O2,corresponding to a chamber pressure of about 0.5 Pa for the selectedpumping speed. The energy distribution functions of the different ionspecies were measured with a combinedmass spectrometer and energyanalyzer. The time-averaged distribution functions were broad and rangedfrom about 30eV to 90 eV at 200 kHz and higher frequencies, while theywere only several eV broad at 50 kHz and lower frequencies, with themaximum located at about 40 eV for the grounded anode case. This maximumwas shifted down to about 7 eV when the anode was floating, indicatingthe important role of the plasma potential for the ion energy for a givensubstrate potential. The source could be scaled to greater length and maybe useful for …
Date:
January 8, 2007
Creator:
Anders, Andre & Yushkov, Georgy Yu.
Object Type:
Article
System:
The UNT Digital Library
First principles calculations of the effect of Pt on NiAl surfaceenergy and the site preference of Pt
Pt-modified NiAl is widely used as a coating material in industry. In this study, the surface energies of NiAl with and without Pt are investigated using first-principles calculations. The presence of Pt in NiAl takes the surface electronic states to higher energies, resulting in an increased surface energy, which explains some of the beneficial effects of Pt on the oxidation resistance of NiAl. The electronic structure of NiAl-Pt alloys is also analyzed in terms of the site preference of Pt in NiAl. Results show that Pt bonds strongly to Al, giving its site preference on the Ni site.
Date:
March 8, 2007
Creator:
Yu, Rong & Hou, Peggy Y.
Object Type:
Article
System:
The UNT Digital Library
Breakdown of Electrostatic Predictions for the Nonlinear Dispersion Relation of a Stimulated Raman Scattering-Driven Plasma Wave
The kinetic nonlinear dispersion relation, and frequency shift {delta}{omega}{sub srs}, of a plasma wave driven by stimulated Raman scattering (SRS) are presented. Our theoretical calculations are fully electromagnetic, and use an adiabatic expression for the electron susceptibility which accounts for the change in phase velocity as the wave grows. When k{lambda}{sub D} {approx}> 0.35 (k being the plasma wave number and {lambda}{sub D} the Debye length), {delta}{omega}{sub srs} is significantly larger than could be inferred by assuming that the wave is freely propagating. Our theory is in excellent agreement with 1-D Eulerian Vlasov-Maxwell simulations when 0.3 {le} k{lambda}{sub D} {le} 0.58, and allows discussion of previously proposed mechanisms for Raman saturation. In particular, we find that no 'loss of resonance' of the plasma wave would limit the Raman growth rate, and that saturation through a phase detuning between the plasma wave and the laser drive is mitigated by wave number shifts.
Date:
May 8, 2007
Creator:
Benisti, D; Strozzi, D J & Gremillet, L
Object Type:
Article
System:
The UNT Digital Library
Substrate-induced band gap opening in epitaxial graphene
Graphene has shown great application potential as the hostmaterial for next-generation electronic devices. However, despite itsintriguing properties, one of the biggest hurdles for graphene to beuseful as an electronic material is the lack of an energy gap in itselectronic spectra. This, for example, prevents the use of graphene inmaking transistors. Although several proposals have been made to open agap in graphene's electronic spectra, they all require complexengineering of the graphene layer. Here, we show that when graphene isepitaxially grown on SiC substrate, a gap of ~;0.26 eV is produced. Thisgap decreases as the sample thickness increases and eventually approacheszero when the number of layers exceeds four. We propose that the originof this gap is the breaking of sublattice symmetry owing to thegraphene-substrate interaction. We believe that our results highlight apromising direction for band gap engineering of graphene.
Date:
September 8, 2007
Creator:
Zhou, S. Y.; Gweon, G.-H.; Fedorov, A. V.; First, P. N.; de Heer, W. A.; Lee, D.-H. et al.
Object Type:
Article
System:
The UNT Digital Library
Experimental measurements of the 15O(alpha,gamma)19Ne reaction rate and the stability of thermonuclear burning on accreting neutron stars
Neutron stars in close binary star systems often accrete matter from their companion stars. Thermonuclear ignition of the accreted material in the atmosphere of the neutron star leads to a thermonuclear explosion which is observed as an X-ray burst occurring periodically between hours and days depending on the accretion rate. The ignition conditions are characterized by a sensitive interplay between the accretion rate of the fuel supply and its depletion rate by nuclear burning in the hot CNO cycle and the rp-process. For accretion rates close to stable burning the burst ignition therefore depends critically on the hot CNO breakout reaction {sup 15}O({alpha}, {gamma}){sup 19}Ne that regulates the flow between the hot CNO cycle and the rapid proton capture process. Until recently, the {sup 15}O({alpha}, {gamma}){sup 19}Ne reaction rate was not known experimentally and the theoretical estimates carried significant uncertainties. In this paper we perform a parameter study of the uncertainty of this reaction rate and determine the astrophysical consequences of the first measurement of this reaction rate. Our results corroborate earlier predictions and show that theoretically burning remains unstable up to accretion rates near the Eddington limit, in contrast to astronomical observations.
Date:
May 8, 2007
Creator:
Fisker, J.; Tan, W.; Goerres, J.; Wiescher, M. & Cooper, R.
Object Type:
Article
System:
The UNT Digital Library
Strain dependence of the Mn anisotropy in ferromagnetic semiconductors observed by x-ray magnetic circular dichroism
None
Date:
May 8, 2007
Creator:
Arenholz, Elke; Edmonds, K.W.; van der Laan, G.; Farley, N.R.S.; Arenholz, E.; Campion, R.P. et al.
Object Type:
Article
System:
The UNT Digital Library
A Potential Application of Uncertainty Analysis to Doe-Std-3009-94 Accident Analysis
None
Date:
May 8, 2007
Creator:
Palmrose, D. E. & Yang, J. M.
Object Type:
Article
System:
The UNT Digital Library
Distance-Two Interpolation for Parallel Algebraic Multigrid
Algebraic multigrid (AMG) is one of the most efficient and scalable parallel algorithms for solving sparse linear systems on unstructured grids. However, for large three-dimensional problems, the coarse grids that are normally used in AMG often lead to growing complexity in terms of memory use and execution time per AMG V-cycle. Sparser coarse grids, such as those obtained by the Parallel Modified Independent Set coarsening algorithm (PMIS) [7], remedy this complexity growth, but lead to non-scalable AMG convergence factors when traditional distance-one interpolation methods are used. In this paper we study the scalability of AMG methods that combine PMIS coarse grids with long distance interpolation methods. AMG performance and scalability is compared for previously introduced interpolation methods as well as new variants of them for a variety of relevant test problems on parallel computers. It is shown that the increased interpolation accuracy largely restores the scalability of AMG convergence factors for PMIS-coarsened grids, and in combination with complexity reducing methods, such as interpolation truncation, one obtains a class of parallel AMG methods that enjoy excellent scalability properties on large parallel computers.
Date:
May 8, 2007
Creator:
De Sterck, H; Falgout, R; Nolting, J & Yang, U M
Object Type:
Article
System:
The UNT Digital Library
Berkeley Seismological Laboratory Seismic Moment Tensor Report for the August 6, 2007 M3.9 Seismic event in central Utah
We have performed a complete moment tensor analysis of the seismic event, which occurred on Monday August 6, 2007 at 08:48:40 UTC 21 km from Mt.Pleasant, Utah. In our analysis we utilized complete three-component seismic records recorded by the USArray, University of Utah, and EarthScope seismic arrays. The seismic waveform data was integrated to displacement and filtered between 0.02 to 0.10 Hz following instrument removal. We used the Song et al. (1996) velocity model to compute Green's functions used in the moment tensor inversion. A map of the stations we used and the location of the event is shown in Figure 1. In our moment tensor analysis we assumed a shallow source depth of 1 km consistent with the shallow depth reported for this event. As shown in Figure 2 the results point to a source mechanism with negligible double-couple radiation and is composed of dominant CLVD and implosive isotropic components. The total scalar seismic moment is 2.12e22 dyne cm corresponding to a moment magnitude (Mw) of 4.2. The long-period records are very well matched by the model (Figure 2) with a variance reduction of 73.4%. An all dilational (down) first motion radiation pattern is predicted by the moment tensor …
Date:
August 8, 2007
Creator:
Ford, S.; Dreger, D. & Hellweg, P.
Object Type:
Report
System:
The UNT Digital Library
Experimental study of radium partitioning between anorthite and melt at 1 atm
We present the first experimental radium mineral/melt partitioning data, specifically between anorthite and a CMAS melt at atmospheric pressure. Ion microprobe measurement of coexisting anorthite and glass phases produces a molar D{sub Ra} = 0.040 {+-} 0.006 and D{sub Ra}/D{sub Ba} = 0.23 {+-} 0.05 at 1400 C. Our results indicate that lattice strain partitioning models fit the divalent (Ca, Sr, Ba, Ra) partition coefficient data of this study well, supporting previous work on crustal melting and magma chamber dynamics that has relied on such models to approximate radium partitioning behavior in the absence of experimentally determined values.
Date:
March 8, 2007
Creator:
Miller, S.; Burnett, D.; Asimow, P.; Phinney, D. & Hutcheon, I.
Object Type:
Article
System:
The UNT Digital Library
The Spin- and Angel-Resolved Photelectron Spectrometer
A spin- and angle-resolved x-ray photoelectron spectrometer for the study of magnetic materials will be discussed. It consists of a turntable with electron lenses connected to a large hemispherical analyzer. A mini-Mott spin detector is fitted to the output of the hemispherical analyzer. This system, when coupled to a synchrotron radiation source will allow determination of a complete set of quantum numbers of a photoelectron. This instrument will be used to study ferromagnetic, antiferromagnetic and nonmagnetic materials. Some prototypical materials systems to be studied with this instrument system will be proposed.
Date:
May 8, 2007
Creator:
Mankey, G J; Morton, S A; Tobin, J G; Yu, S W & Waddill, G D
Object Type:
Article
System:
The UNT Digital Library
Greensheet (Houston, Tex.), Vol. 38, No. 476, Ed. 1 Thursday, November 8, 2007
Free weekly newspaper that includes business and classified advertising.
Date:
November 8, 2007
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 37, No. 632, Ed. 1 Thursday, February 8, 2007
Free weekly newspaper that includes business and classified advertising.
Date:
February 8, 2007
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 38, No. 157, Ed. 1 Tuesday, May 8, 2007
Free weekly newspaper that includes business and classified advertising.
Date:
May 8, 2007
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 38, No. 214, Ed. 1 Friday, June 8, 2007
Free weekly newspaper that includes business and classified advertising.
Date:
June 8, 2007
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Greensheet (Houston, Tex.), Vol. 38, No. 158, Ed. 1 Tuesday, May 8, 2007
Free weekly newspaper that includes business and classified advertising.
Date:
May 8, 2007
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History