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Similarity-Guided Streamline Placement with Error Evaluation

Description: Most streamline generation algorithms either provide a particular density of streamlines across the domain or explicitly detect features, such as critical points, and follow customized rules to emphasize those features. However, the former generally includes many redundant streamlines, and the latter requires Boolean decisions on which points are features (and may thus suffer from robustness problems for real-world data). We take a new approach to adaptive streamline placement for steady vector… more
Date: August 15, 2007
Creator: Chen, Y.; Cohen, J. D. & Krolik, J. H.
Partner: UNT Libraries Government Documents Department
open access

Increasing FTIR spectromicroscopy speed and resolution through compressive imaging

Description: At the Advanced Light Source at Lawrence Berkeley National Laboratory, we are investigating how to increase both the speed and resolution of synchrotron infrared imaging. Synchrotron infrared beamlines have diffraction-limited spot sizes and high signal to noise, however spectral images must be obtained one point at a time and the spatial resolution is limited by the effects of diffraction. One technique to assist in speeding up spectral image acquisition is described here and uses compressive … more
Date: October 15, 2007
Creator: Gallet, Julien; Riley, Michael; Hao, Zhao & Martin, Michael C
Partner: UNT Libraries Government Documents Department
open access

Spatial resolution limits for synchrotron-based infrared spectromicroscopy

Description: Detailed spatial resolution tests were performed on beamline 1.4.4 at the Advanced Light Source synchrotron facility in Berkeley, CA. The high-brightness synchrotron source is coupled at this beamline to a Thermo-Electron Continumum XL infrared microscope. Two types of resolution tests in both the mid-IR (using a KBr beamsplitter and an MCT-A* detector) and in the near-IR (using a CaF2 beamsplitter and an InGaAS detector) were performed and compared to a simple diffraction-limited spot size mod… more
Date: October 15, 2007
Creator: Levenson, Erika; Lerch, Philippe & Martin, Michael C.
Partner: UNT Libraries Government Documents Department
open access

Tile-based Level of Detail for the Parallel Age

Description: Today's PCs incorporate multiple CPUs and GPUs and are easily arranged in clusters for high-performance, interactive graphics. We present an approach based on hierarchical, screen-space tiles to parallelizing rendering with level of detail. Adapt tiles, render tiles, and machine tiles are associated with CPUs, GPUs, and PCs, respectively, to efficiently parallelize the workload with good resource utilization. Adaptive tile sizes provide load balancing while our level of detail system allows tot… more
Date: August 15, 2007
Creator: Niski, K. & Cohen, J. D.
Partner: UNT Libraries Government Documents Department
open access

Optimal Heat Collection Element Shapes for Parabolic Trough Concentrators

Description: For nearly 150 years, the cross section of the heat collection tubes used at the focus of parabolic trough solar concentrators has been circular. This type of tube is obviously simple and easily fabricated, but it is not optimal. It is shown in this article that the optimal shape, assuming a perfect parabolic figure for the concentrating mirror, is instead oblong, and is approximately given by a pair of facing parabolic segments.
Date: November 15, 2007
Creator: Bennett, C
Partner: UNT Libraries Government Documents Department
open access

Sequence finishing and mapping of Drosophila melanogasterheterochromatin

Description: Genome sequences for most metazoans are incomplete due tothe presence of repeated DNA in the pericentromeric heterochromatin. Theheterochromatic regions of D. melanogaster contain 20 Mb of sequenceamenable to mapping, sequence assembly and finishing. Here we describethe generation of 15 Mb of finished or improved heterochromatic sequenceusing available clone resources and assembly and mapping methods. We alsoconstructed a BAC-based physical map that spans approximately 13 Mb ofthe pericentromer… more
Date: June 15, 2007
Creator: Hoskins, Roger A.; Carlson, Joseph W.; Kennedy, Cameron; Acevedo,David; Evans-Holm, Martha; Frise, Erwin et al.
Partner: UNT Libraries Government Documents Department
open access

Soft Error Vulnerability of Iterative Linear Algebra Methods

Description: Devices become increasingly vulnerable to soft errors as their feature sizes shrink. Previously, soft errors primarily caused problems for space and high-atmospheric computing applications. Modern architectures now use features so small at sufficiently low voltages that soft errors are becoming significant even at terrestrial altitudes. The soft error vulnerability of iterative linear algebra methods, which many scientific applications use, is a critical aspect of the overall application vulner… more
Date: December 15, 2007
Creator: Bronevetsky, G & de Supinski, B
Partner: UNT Libraries Government Documents Department
open access

Environmental Stewardship: How Semiconductor Suppliers Help to Meet Energy-Efficiency Regulations and Voluntary Specifications in China

Description: Recognizing the role that semiconductor suppliers can playin meeting energy-efficiency regulations and voluntary specifications,this paper provides an overview of Chinese policies and implementingbodies; a discussion of current programs, their goals, and effectiveness;and possible steps that can be taken tomeet these energy-efficiencyrequirements while also meeting products' high performance and costgoals.
Date: January 15, 2007
Creator: Aizhen, Li; Fanara, Andrew; Fridley, David; Merriman, Louise & Ju, Jeff
Partner: UNT Libraries Government Documents Department
open access

Organic carbon distribution, speciation, and elementalcorrelations within soil microaggregates: applications of STXM and NEXAFSspectroscopy

Description: Soils contain the largest inventory of organic carbon on the Earth's surface. Therefore, it is important to understand how soil organic carbon (SOC) is distributed in soils. This study directly measured SOC distributions within soil microaggregates and its associations with major soil elements from three soil groups (Phaeozem, Cambisol, and Ultisol), using scanning transmission X-ray microscopy (STXM) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at a spatial resolution of… more
Date: March 15, 2007
Creator: Wan, Jiamin; Tyliszczak, Tolek & Tokunaga, Tetsu K.
Partner: UNT Libraries Government Documents Department
open access

Fission Product Gamma-Ray Line Pairs Sensitive to Fissile Material and Neutron Energy

Description: The beta-delayed gamma-ray spectra from the fission of {sup 235}U, {sup 238}U, and {sup 239}Pu by thermal and near-14-MeV neutrons have been measured for delay times ranging from 1 minute to 14 hours. Spectra at all delay times contain sets of prominent gamma-ray lines with intensity ratios that identify the fissile material and distinguish between fission induced by low-energy or high-energy neutrons.
Date: November 15, 2007
Creator: Marrs, R. E.; Norman, E. B.; Burke, J. T.; Macri, R. A.; Shugart, H. A.; Browne, E. et al.
Partner: UNT Libraries Government Documents Department
open access

The Life-cycle of Operons

Description: Operons are a major feature of all prokaryotic genomes, buthow and why operon structures vary is not well understood. To elucidatethe life-cycle of operons, we compared gene order between Escherichiacoli K12 and its relatives and identified the recently formed anddestroyed operons in E. coli. This allowed us to determine how operonsform, how they become closely spaced, and how they die. Our findingssuggest that operon evolution may be driven by selection on geneexpression patterns. First, both … more
Date: March 15, 2007
Creator: Price, Morgan N.; Arkin, Adam P. & Alm, Eric J.
Partner: UNT Libraries Government Documents Department
open access

Optimal Technology Selection and Operation of Microgrids inCommercial Buildings

Description: The deployment of small (<1-2 MW) clusters of generators,heat and electrical storage, efficiency investments, and combined heatand power (CHP) applications (particularly involving heat activatedcooling) in commercial buildings promises significant benefits but posesmany technical and financial challenges, both in system choice and itsoperation; if successful, such systems may be precursors to widespreadmicrogrid deployment. The presented optimization approach to choosingsuch systems and their o… more
Date: January 15, 2007
Creator: Marnay, Chris; Venkataramanan, Giri; Stadler, Michael; Siddiqui,Afzal; Firestone, Ryan & Chandran, Bala
Partner: UNT Libraries Government Documents Department
open access

Microwave Ion Source and Beam Injection for an Accelerator-drivenNeutron Source

Description: An over-dense microwave driven ion source capable ofproducing deuterium (or hydrogen) beams at 100-200 mA/cm2 and with atomicfraction>90 percent was designed and tested with an electrostaticlow energy beam transport section (LEBT). This ion source wasincorporatedinto the design of an Accelerator Driven Neutron Source(ADNS). The other key components in the ADNS include a 6 MeV RFQaccelerator, a beam bending and scanning system, and a deuterium gastarget. In this design a 40 mA D+ beam is produce… more
Date: February 15, 2007
Creator: Vainionpaa, J. H.; Gough, R.; Hoff, M.; Kwan, J. W.; Ludewigt, B. A.; Regis, M. J. et al.
Partner: UNT Libraries Government Documents Department
open access

Baryon Triality And Neutrino Masses From An Anomalous FlavorU(1)

Description: We construct a concise U(1){sub X} Froggatt-Nielsen model in which baryon triality, a discrete gauge Z{sub 3}-symmetry, arises from U(1){sub X} breaking. The proton is thus stable, however, R-parity is violated. With the proper choice of U(1){sub X} charges we can obtain neutrino masses and mixings consistent with an explanation of the atmospheric and solar neutrino anomalies in terms of neutrino oscillations, with no right-handed neutrinos required. The only mass scale apart from M{sub grav} i… more
Date: August 15, 2007
Creator: Dreiner, Herbi K.; Luhn, Christoph; Murayama, Hitoshi & Thormeier,Marc
Partner: UNT Libraries Government Documents Department
open access

Detection of low energy single ion impacts in micron scaletransistors at room temperature

Description: We report the detection of single ion impacts throughmonitoring of changes in the source-drain currents of field effecttransistors (FET) at room temperature. Implant apertures are formed inthe interlayer dielectrics and gate electrodes of planar, micro-scaleFETs by electron beam assisted etching. FET currents increase due to thegeneration of positively charged defects in gate oxides when ions(121Sb12+, 14+, Xe6+; 50 to 70 keV) impinge into channel regions. Implantdamage is repaired by rapid the… more
Date: October 15, 2007
Creator: Batra, A.; Weis, C. D.; Reijonen, J.; Persaud, A.; Schenkel, T.; Cabrini, S. et al.
Partner: UNT Libraries Government Documents Department
open access

John Pendry: His Contributions to the Development of LEED Surface Crystallography

Description: In this paper we discuss the pivotal role played by Sir John Pendry in the development of Low Energy Electron Diffraction (LEED) during the past three decades; the earliest understanding on the physics of LEED to the development of sophisticated methods for the structural solution of complex surfaces.
Date: October 15, 2007
Creator: Somorjai, Gabor A. & Rous, P. J.
Partner: UNT Libraries Government Documents Department
open access

The National Ignition Facility: The world's largest optical system

Description: The National Ignition Facility (NIF), a 192-beam fusion laser, is presently under construction at the Lawrence Livermore National Laboratory with an expected completion in 2008. The facility contains 7,456 meter-scale optics for amplification, beam steering, vacuum barriers, focusing, polarization rotation, and wavelength conversion. A multiphase program was put in place to increase the monthly optical manufacturing rate by up to 20x while simultaneously reducing cost by up to 3x through a sub-… more
Date: October 15, 2007
Creator: Stolz, C J
Partner: UNT Libraries Government Documents Department
open access

High intensity production of high and medium charge state uraniumand other heavy ion beams with VENUS

Description: The next generation, superconducting ECR ion source VENUS(Versatile ECR ion source for NUclear Science) started operation with 28GHzmicrowave heating in 2004. Since then it has produced world recordion beam intensities. For example, 2850 e mu A of O6+, 200 e mu A of U33+or U34+, and in respect to high charge state ions, 1 e mu A of Ar18+, 270e mu A of Ar16+, 28 e mu A of Xe35+ and 4.9 e mu A of U47+ have beenproduced. A brief overview of the latest developments leading to theserecord intensitie… more
Date: November 15, 2007
Creator: Leitner, Daniela; Galloway, Michelle L.; Loew, Timothy J.; Lyneis, Claude M.; Castro-Rodriguez, Ingrid & Todd, Damon S.
Partner: UNT Libraries Government Documents Department
open access

Templated Control of Au nanospheres in Silica Nanowires

Description: The formation of regularly-spaced metal nanostructures in selectively-placed insulating nanowires is an important step toward realization of a wide range of nano-scale electronic and opto-electronic devices. Here we report templated synthesis of Au nanospheres embedded in silica nanowires, with nanospheres consistently spaced with a period equal to three times their diameter. Under appropriate conditions, nanowires form exclusively on Si nanostructures because of enhanced local oxidation and re… more
Date: March 15, 2007
Creator: Tringe, J. W.; Vanamu, G. & Zaidi, S. H.
Partner: UNT Libraries Government Documents Department
open access

Parallel Computation of Three-Dimensional Flows using Overlapping Grids with Adaptive Mesh Refinement

Description: This paper describes an approach for the numerical solution of time-dependent partial differential equations in complex three-dimensional domains. The domains are represented by overlapping structured grids, and block-structured adaptive mesh refinement (AMR) is employed to locally increase the grid resolution. In addition, the numerical method is implemented on parallel distributed-memory computers using a domain-decomposition approach. The implementation is flexible so that each base grid wit… more
Date: November 15, 2007
Creator: Henshaw, W & Schwendeman, D
Partner: UNT Libraries Government Documents Department
open access

Effect of Saline Waste Solution Infiltration Rates on Uranium Retention and Spatial Distribution in Hanford Sediments

Description: The accidental overfilling of waste liquid from tank BX-102 at the Hanford Site in 1951 put about 10 metric tons of U(VI) into the vadose zone. In order to understand the dominant geochemical reactions and transport processes occurred during the initial infiltration and help understand current spatial distribution, we simulated the waste liquid spilling event in laboratory sediment columns using synthesized metal waste solution. We found that, as the plume propagating through sediments, pH decr… more
Date: March 15, 2007
Creator: Wan, Jiamin; Tokunaga, Tetsu K.; Kim, Yongman; Wang, Zheming; Lanzirotti, Antonio; Saiz, Eduardo et al.
Partner: UNT Libraries Government Documents Department
open access

Analysis of pumping-induced unsaturated regions beneath aperennial river

Description: The presence of an unsaturated region beneath a streambedduring groundwater pumping near streams reduces the pumping capacity whenit reaches the well screens, changes flow paths, and alters the types ofbiological transformations in the streambed sediments. Athree-dimensional, multi-phase flow model of two horizontal collectorwells along the Russian River near Forestville, California was developedto investigate the impact of varying the ratio of the aquifer tostreambed permeability on (1) the fo… more
Date: May 15, 2007
Creator: Su, G.W.; Jasperse, J.; Seymour, D.; Constantz, J. & Zhou, Q.
Partner: UNT Libraries Government Documents Department
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