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LOWER BOUNDS ON SELF-FOCUSING SO AS TO MAINTAIN RING INTEGRITY NEAR THE INITIATION OF ACCELERATION IN AN ELECTRON RING ACCELERATOR

Description: Relationships necessary for ring stability are derived between the self-focusing forces of an electron ring and the magnetic field gradient defocusing forces present near and just subsequent to the start of ring acceleration.
Date: April 16, 1970
Creator: Pellegrini, Claudio & Sessler, Andrew.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Resonant Soft X-Ray Contrast Variation Methods as Composition-Specific Probes of Thin Polymer Film Structure

Description: We have developed complementary soft x-ray scattering and reflectometry techniques that allow for the morphological analysis of thin polymer films without resorting to chemical modification or isotopic 2 labeling. With these techniques, we achieve significant, x-ray energy-dependent contrast between carbon atoms in different chemical environments using soft x-ray resonance at the carbon edge. Because carbon-containing samples absorb strongly in this region, the scattering length density depends… more
Date: April 4, 2008
Creator: Welch, Cynthia; Welch, Cynthia F.; Hjelm, Rex P.; Mang, Joseph T.; Hawley, Marilyn E.; Wrobleski, Debra A. et al.
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Partner: UNT Libraries Government Documents Department
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Breaking the Curse of Cardinality on Bitmap Indexes

Description: Bitmap indexes are known to be efficient for ad-hoc range queries that are common in data warehousing and scientific applications. However, they suffer from the curse of cardinality, that is, their efficiency deteriorates as attribute cardinalities increase. A number of strategies have been proposed, but none of them addresses the problem adequately. In this paper, we propose a novel binned bitmap index that greatly reduces the cost to answer queries, and therefore breaks the curse of cardinali… more
Date: April 4, 2008
Creator: Wu, Kesheng; Wu, Kesheng; Stockinger, Kurt & Shoshani, Arie
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Surface species formed by the adsorption and dissociation of water molecules on Ru(0001) surface containing a small coverage of carbon atoms studied by scanning tunneling microscopy

Description: The adsorption and dissociation of water on a Ru(0001) surface containing a small amount ({le} 3 %) of carbon impurities was studied by scanning tunneling microscopy (STM). Various surface species are formed depending on the temperature. These include molecular H{sub 2}O, H{sub 2}O-C complexes, H, O, OH and CH. Clusters of either pure H{sub 2}O or mixed H{sub 2}O-OH species are also formed. Each of these species produces a characteristic contrast in the STM images and can be identified by exper… more
Date: April 26, 2008
Creator: UCB, Dept of Materials Science and Engineering
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Partner: UNT Libraries Government Documents Department
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System-level modeling for geological storage of CO2

Description: One way to reduce the effects of anthropogenic greenhousegases on climate is to inject carbon dioxide (CO2) from industrialsources into deep geological formations such as brine formations ordepleted oil or gas reservoirs. Research has and is being conducted toimprove understanding of factors affecting particular aspects ofgeological CO2 storage, such as performance, capacity, and health, safetyand environmental (HSE) issues, as well as to lower the cost of CO2capture and related processes. Howe… more
Date: April 24, 2006
Creator: Zhang, Yingqi; Oldenburg, Curtis M.; Finsterle, Stefan & Bodvarsson, Gudmundur S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Electrical Contacts to Individual Colloidal Semiconductor Nanorods

Description: We report the results of charge transport studies on single CdTe nanocrystals contacted via evaporated Pd electrodes. Device charging energy, E{sub c}, monitored as a function of electrode separation drops suddenly at separations below {approx}55 nm. This drop can be explained by chemical changes induced by the metal electrodes. This explanation is corroborated by ensemble X-Ray photoelectron spectroscopy (XPS) studies of CdTe films as well as single particle measurements by transmission electr… more
Date: April 1, 2008
Creator: Trudeau, Paul-Emile; Sheldon, Matt; Altoe, Virginia & Alivisatos, A. Paul
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Partner: UNT Libraries Government Documents Department

Long-term Stability of Biogeochemically Reduced U and Cr in Contaminated Sediments

Description: The general goal of this report is to diminish concentrations of metals/radionuclide in groundwaters of contaminated sites to below MCL values through reduction to lower solubility species.
Date: April 19, 2007
Creator: Tetsu Tokunaga, Jiamin Wan, Yongman Kim, Terry Hazen, Eoin Brodie, Zuoping Zheng, Jackie Pena
Item Type: Refine your search to only Presentation
Partner: UNT Libraries Government Documents Department
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The Absence of Plasma in"Spark Plasma Sintering"

Description: Spark plasma sintering (SPS) is a remarkable method for synthesizing and consolidating a large variety of both novel and traditional materials. The process typically uses moderate uni-axial pressures (<100 MPa) in conjunction with a pulsing on-off DC current during operation. There are a number of mechanisms proposed to account for the enhanced sintering abilities of the SPS process. Of these mechanisms, the one most commonly put forth and the one that draws the most controversy involves the… more
Date: April 10, 2008
Creator: Hulbert, Dustin M.; Anders, Andre; Dudina, Dina V.; Andersson, Joakim; Jiang, Dongtao; Unuvar, Cosan et al.
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Partner: UNT Libraries Government Documents Department
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Electronic structure effects in liquid water studied by photoelectron spectroscopy and density functional theory

Description: We present valence photoelectron emission spectra of liquid water in comparison with gas-phase water, ice close to the melting point, low temperature amorphous and crystalline ice. All aggregation states have major electronic structure changes relative to the free molecule, with rehybridization and development of bonding and anti-bonding states accompanying the hydrogen bond formation. Sensitivity to the local structural order, most prominent in the shape and splitting of the occupied 3a{sub 1}… more
Date: April 29, 2008
Creator: Nordlund, Dennis; Odelius, Michael; Bluhm, Hendrik; Ogasawara, Hirohito; Pettersson, Lars G.M. & Nilsson, Anders
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Supercomputers: Super-polluters?

Description: Thanks to imperatives for limiting waste heat, maximizing performance, and controlling operating cost, energy efficiency has been a driving force in the evolution of supercomputers. The challenge going forward will be to extend these gains to offset the steeply rising demands for computing services and performance.
Date: April 8, 2008
Creator: Mills, Evan; Mills, Evan; Tschudi, William; Shalf, John & Simon, Horst
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Partner: UNT Libraries Government Documents Department
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Toward fully self-consistent simulation of the interaction of E-Clouds and beams with WARP-POSINST

Description: To predict the evolution of electron clouds and their effect on the beam, the high energy physics community has relied so far on the complementary use of 'buildup' and 'single/multi-bunch instability' reduced descriptions. The former describes the evolution of electron clouds at a given location in the ring, or 'station', under the influence of prescribed beams and external fields [1], while the latter (sometimes also referred as the 'quasi-static' approximation [2]) follows the interaction bet… more
Date: April 9, 2012
Creator: Lawrence Livermore National Laboratory
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Multi-year search for a diffuse flxu of muon neutrinos with AMANDA-II

Description: A search for TeV-PeV muon neutrinos from unresolved sources was performed on AMANDA-II data collected between 2000 and 2003 with an equivalent livetime of 807 days. This diffuse analysis sought to find an extraterrestrial neutrino flux from sources with non-thermal components. The signal is expected to have a harder spectrum than the atmospheric muon and neutrino backgrounds. Since no excess of events was seen in the data over the expected background, an upper limit of E{sup 2}{Phi}{sub 90%C.L.… more
Date: April 13, 2008
Creator: Collaboration, IceCube; Klein, Spencer; Achterberg, A. & Collaboration, IceCube
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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LUsim: A Framework for Simulation-Based Performance Modelingand Prediction of Parallel Sparse LU Factorization

Description: Sparse parallel factorization is among the most complicated and irregular algorithms to analyze and optimize. Performance depends both on system characteristics such as the floating point rate, the memory hierarchy, and the interconnect performance, as well as input matrix characteristics such as such as the number and location of nonzeros. We present LUsim, a simulation framework for modeling the performance of sparse LU factorization. Our framework uses micro-benchmarks to calibrate the param… more
Date: April 15, 2008
Creator: Univ. of California, San Diego
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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On the Suitability of Lanthanides as Actinide Analogs

Description: With the current level of actinide materials used in civilian power generation and the need for safe and efficient methods for the chemical separation of these species from their daughter products and for long-term storage requirements, a detailed understanding of actinide chemistry is of great importance. Due to the unique bonding properties of the f-elements, the lanthanides are commonly used as structural and chemical models for the actinides, but differences in the bonding between these 4f … more
Date: April 11, 2008
Creator: Szigethy, Geza & Raymond, Kenneth N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The silicon microstrip sensors of the ATLAS semiconductor tracker

Description: This paper describes the AC-coupled, single-sided, p-in-n silicon microstrip sensors used in the Semiconductor Tracker (SCT) of the ATLAS experiment at the CERN Large Hadron Collider (LHC). The sensor requirements, specifications and designs are discussed, together with the qualification and quality assurance procedures adopted for their production. The measured sensor performance is presented, both initially and after irradiation to the fluence anticipated after 10 years of LHC operation. The … more
Date: April 13, 2007
Creator: Collaboration, ATLAS SCT & Spieler, Helmuth G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A Coupled Model for Natural Convection and Condensation in HeatedSubsurface Enclosures Embedded in Fractured Rock

Description: In heated tunnels such as those designated for emplacementof radioactive waste at Yucca Mountain, axial temperature gradients maycause natural convection processes that can significantly influence themoisture conditions in the tunnels and in the surrounding fractured rock.Large-scale convection cells would provide an effective mechanism foraxial vapor transport, driving moisture out of the formation away fromthe heated tunnel section into cool end sections (where no waste isemplaced). To study … more
Date: April 14, 2006
Creator: Halecky, N.; Birkholzer, J. T.; Webb, S. W.; Peterson, P. F. & Bodvarsson, G. S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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NATURAL CONVECTION IN PASSIVE SOLAR BUILDINGS: EXPERIMENTS, ANALYSIS AND RESULTS

Description: Computer programs have been developed to numerically simulate natural convection in two- and three-dimensional room geometries. The programs have been validated using published data from the literature, results from a full-scale experiment performed at the Massachusetts Institute of Technology, and results from a small-scale experiment performed at LBL. One of the computer programs has been used to study the influence of natural convection on the thermal performance of a single zone in a direct… more
Date: April 1, 1981
Creator: Gadgil, A.; Bauman, F. & Kammerud, R.
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Partner: UNT Libraries Government Documents Department
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Kaolinite dissolution and precipitation kinetics at 22oC and pH 4

Description: Dissolution and precipitation rates of low defect Georgia kaolinite (KGa-1b) as a function of Gibbs free energy of reaction (or reaction affinity) were measured at 22 C and pH 4 in continuously stirred flowthrough reactors. Steady state dissolution experiments showed slightly incongruent dissolution, with a Si/Al ratio of about 1.12 that is attributed to the re-adsorption of Al on to the kaolinite surface. No inhibition of the kaolinite dissolution rate was apparent when dissolved aluminum was … more
Date: April 1, 2008
Creator: Steefel, Carl; Yang, L. & Steefel, C.I.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Performances of Multi-Level and Multi-Component Compressed BitmapIndices

Description: This paper presents a systematic study of two large subsetsof bitmap indexing methods that use multi-component and multi-levelencodings. Earlier studies on bitmap indexes are either empirical or foruncompressed versions only. Since most of bitmap indexes in use arecompressed, we set out to study the performance characteristics of thesecompressed indexes. To make the analyses manageable, we choose to use aparticularly simple, but efficient, compression method called theWord-Aligned Hybrid (WAH) … more
Date: April 30, 2007
Creator: Wu, Kesheng; Stockinger, Kurt & Shoshani, Arie
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Frustrated spin correlations in diluted spin ice Ho2-xLaxTi2O7

Description: We have studied the evolution of the structural properties as well as the static and dynamic spin correlations of spin ice Ho2Ti2O7, where Ho was partially replaced by non-magnetic La. The crystal structure of diluted samples Ho2-xLaxTi2O7 was characterized by x-ray and neutron diffraction and by Ho L-III-edge and Ti K-edge extended x-ray absorption fine structure (EXAFS) measurements. It is found that the pyrochlore structure remains intact until about x = 0.3, but a systematic increase in loc… more
Date: April 30, 2008
Creator: Ehlers, Georg; Ehlers, G.; Mamontov, E.; Zamponi, M.; Faraone, A.; Qiu, Y. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Preparation of Size-tunable, Highly Monodisperse PVP-Protected Pt-nanoparticles by Seed-mediated Growth

Description: We demonstrate a preparative method which produces highly-monodisperse Pt-nanoparticles of tunable size without the external addition of seed particles. Hexachloroplatinic acid is dosed slowly to an ethylene glycol solution at 120 C and reduced in the presence of a stabilizing polymer poly-N-vinylpyrollidone (PVP). Slow addition of the Pt-salt first will first lead to the formation of nuclei (seeds) which then grow further to produce larger particles of any desired size between 3 and 8nm. The a… more
Date: April 2, 2008
Creator: Koebel, Matthias Michael; Jones, Louis C. & Somorjai, Gabor A.
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Partner: UNT Libraries Government Documents Department
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A HIGH-RESOLUTION HIGH-LUMINOSITY BETA-RAY SPECTROMETER DESIGN EMPLOYING AZIMUTHALLY VARYING MAGNETIC FIELDS

Description: A double-focusing magnetic field for a spectrometer of the flat type which gives radial focusing to roughly the sixth order, and which utilizes azimuthal variation of the field coefficients, has been devised.
Date: April 6, 1966
Creator: Bergkvist, Karl-Erik & Sessler, Andrew M.
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Partner: UNT Libraries Government Documents Department
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TRANSVERSE COHERENT RESISTIVE INSTABILITIES OF AZIMUTHALLY BUNCHED BEAMS IN PARTICLE ACCELERATORS

Description: The transverse electromagnetic coupling of bunches of particles with each other is investigated theoretically, and shown to incorporate the possibility (due to the effect of nonperfectly conducting vacuum chamber walls) of coherent instability even when the longitudinal distance between bunches is much larger than the transverse dimensions of the vacuum tank. The modes of oscillation in which the bunches move rigidly are investigated; criteria for stability, and expressions for the small amplit… more
Date: April 1, 1966
Creator: Courant, Ernest D. & Sessler, Andrew M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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