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Monolithic Nickel (II) Oxide Aerogels Using an Organic Epoxide: The Importance of the Counter Ion

Description: The synthesis and characterization of nickel (II) oxide aerogel materials prepared using the epoxide addition method is described. The addition of the organic epoxide propylene oxide to an ethanolic solution of NiCl{sub 2} 6H{sub 2}O resulted in the formation of an opaque light green monolithic gel and subsequent drying with supercritical CO{sub 2} gave a monolithic aerogel material of the same color. This material has been characterized using powder X-ray diffraction, electron microscopy, elem… more
Date: January 13, 2004
Creator: Gash, A. E.; Satcher, J. H. & Simpson, R. L.
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open access

On Multigrid for Overlapping Grids

Description: The solution of elliptic partial differential equations on composite overlapping grids using multigrid is discussed. An approach is described that provides a fast and memory efficient scheme for the solution of boundary value problems in complex geometries. The key aspects of the new scheme are an automatic coarse grid generation algorithm, an adaptive smoothing technique for adjusting residuals on different component grids, and the use of local smoothing near interpolation boundaries. Other im… more
Date: January 13, 2004
Creator: Henshaw, W
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open access

File System Workload Analysis for Large Scale Scientific Computing Applications

Description: Parallel scientific applications require high-performance I/O support from underlying file systems. A comprehensive understanding of the expected workload is therefore essential for the design of high-performance parallel file systems. We re-examine the workload characteristics in parallel computing environments in the light of recent technology advances and new applications. We analyze application traces from a cluster with hundreds of nodes. On average, each application has only one or two ty… more
Date: January 13, 2004
Creator: Wang, Feng; Xin, Qin; Hong, Bo; Brandt, Scott A.; Miller, Ethan L.; Long, Darrell D. E. et al.
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open access

Enhanced Video Surveillance (EVS) with speckle imaging

Description: Enhanced Video Surveillance (EVS) with Speckle Imaging is a high-resolution imaging system that substantially improves resolution and contrast in images acquired over long distances. This technology will increase image resolution up to an order of magnitude or greater for video surveillance systems. The system's hardware components are all commercially available and consist of a telescope or large-aperture lens assembly, a high-performance digital camera, and a personal computer. The system's s… more
Date: January 13, 2004
Creator: Carrano, C J
Item Type: Refine your search to only Report
open access

Preliminary report on self-healing minefield (frogs) concepts and utility in battle

Description: The purpose of this study is to determine battlefield effectiveness of the self-healing minefield (''Frogs'') concept system compared to basecases of the standard AP/AT (anti-personnel/anti-tank) mixed minefield, the AT (anti-tank) pure minefield, and no minefields. This involves tactical modeling where a basecase with and without mines is compared to the concept system. However, it is first necessary to establish system characteristics and behavior of the Frog mine and minefield in order to do… more
Date: January 13, 2000
Creator: Greenwalt, R J & Magnoli, D
Item Type: Refine your search to only Report
open access

Ultra-thick, low-stress nanostructured diamond films

Description: We describe a hot-filament chemical vapor deposition process for growing freestanding nanostructured diamond films, {approx}80 {micro}m thick, with residual tensile stress levels {le} 90 MPa. We characterize the film microstructure, mechanical properties, chemical bond distribution, and elemental composition. Results show that our films are nanostructured with columnar grain diameters of {le} 150 nm and a highly variable grain length along the growth direction of {approx}50-1500 nm. These films… more
Date: January 13, 2005
Creator: Kucheyev, S O; Biener, J; Tringe, J W & Wang, Y M
Item Type: Refine your search to only Article
open access

Differential Forms Basis Functions for Better Conditioned Integral Equations

Description: Differential forms offer a convenient way to classify physical quantities and set up computational problems. By observing the dimensionality and type of derivatives (divergence,curl,gradient) applied to a quantity, an appropriate differential form can be chosen for that quantity. To use these differential forms in a simulation, the forms must be discretized using basis functions. The 0-form through 2-form basis functions are formed for surfaces. Twisted 1-form and 2-form bases will be presented… more
Date: January 13, 2005
Creator: Fasenfest, B.; White, D.; Stowell, M.; Rieben, R.; Sharpe, R.; Madsen, N. et al.
Item Type: Refine your search to only Article
open access

The Structure of the Cubic Coincident Site Lattice Rotation Group

Description: This work is intended to be a mathematical underpinning for the field of grain boundary engineering and its relatives. The interrelationships within the set of rotations producing coincident site lattices in cubic crystals are examined in detail. Besides combining previously established but widely scattered results into a unified context, the present work details newly developed representations of the group structure in terms of strings of generators (based on quaternionic number theory, and in… more
Date: January 13, 2004
Creator: Reed, B W; Minich, R W; Rudd, R E & Kumar, M
Item Type: Refine your search to only Article
open access

Fast Wavefront Reconstruction in Large Adaptive Optics Systems Using the Fourier Transform

Description: Wavefront Reconstruction using the Fast Fourier Transform and spatial filtering is shown to be computationally tractable and sufficiently accurate for use in large Shack Hartmann-based adaptive optics systems (up to at least 10,000 actuators). This method is significantly faster and can have lower noise propagation than traditional VMM reconstructors. The boundary problem which prevented the accurate reconstruction of phase in circular apertures using square-grid FTs is identified and solved. T… more
Date: January 13, 2002
Creator: Poyneer, L; Gravel, D T & Brase, J M
Item Type: Refine your search to only Article
open access

A Detailed Chemical Kinetic Model for TNT

Description: A detailed chemical kinetic mechanism for 2,4,6-tri-nitrotoluene (TNT) has been developed to explore problems of explosive performance and soot formation during the destruction of munitions. The TNT mechanism treats only gas-phase reactions. Reactions for the decomposition of TNT and for the consumption of intermediate products formed from TNT are assembled based on information from the literature and on current understanding of aromatic chemistry. Thermodynamic properties of intermediate and r… more
Date: January 13, 2005
Creator: Pitz, W J & Westbrook, C K
Item Type: Refine your search to only Article
open access

DEVELOPMENTS IN THE MEASUREMENT OF ACTINIDES AND129I AT LLNL BY ACCELERATOR MASS SPECTROMETRY

Description: The application of ultra-sensitive heavy isotope measurements continues to expand in a variety of fields relevant to the management of nuclear materials, including nuclear isotope forensics and radiobioassay. We have developed a heavy isotope accelerator mass spectrometry (AMS) system at Lawrence Livermore National Laboratory's (LLNL) Center for Accelerator Mass Spectrometry (CAMS). The system was designed particularly for the measurement of actinide concentrations and isotopic ratios, but also… more
Date: January 13, 2005
Creator: Brown, T A; Marchetti, A A; Weyhenmeyer, C E; Knezovich, J P; Hamilton, T F & Nimz, G J
Item Type: Refine your search to only Article
open access

Self-Interstitial Transport in Vanadium

Description: We study the diffusion of self-interstitial atoms (SIAs) and SIA clusters in vanadium via molecular dynamics simulations with an improved Finnis-Sinclair potential (fit to first-principles results for SIA structure and energetics). The present results demonstrate that single SIAs exist in a <111>-dumbbell configuration and migrate easily along <111> directions. Changes of direction through rotations into other <111> directions are infrequent at low temperatures, but become pro… more
Date: January 13, 2005
Creator: Zepeda-Ruiz, L A; Rottler, J; Wirth, B D; Car, R & Srolovitz, D J
Item Type: Refine your search to only Article
open access

Simulations of Inertial Confinement Fusion Driven by a Novel Synchrotron Radiation-Based X-Ray Igniter

Description: The advantages and challenges of using a powerful x-ray source for the fast ignition of compressed Inertial Confinement Fusion (ICF) targets have been considered. The requirements for such a source together with the optics to focus the x-rays onto compressed DT cores lead to a conceptual design based on Energy Recovery Linacs (ERLs) and long wigglers to produce x-ray pulses with the appropriate phase space properties. A comparative assessment of the parameters of the igniter system indicates th… more
Date: January 13, 2004
Creator: Shlyaptsev, V & Tatchyn, R
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open access

Application of Novel High Order Time Domain Vector Finite Element Method to Photonic Band-Gap Waveguides

Description: In this paper we motivate the use of a novel high order time domain vector finite element method that is of arbitrary order accuracy in space and up to 5th order accurate in time; and in particular, we apply it to the case of photonic band-gap (PBG) structures. Such structures have been extensively studied in the literature with several practical applications; in particular, for the low loss transmission of electromagnetic energy around sharp 90 degree bends [1]. Typically, such structures are … more
Date: January 13, 2004
Creator: Rieben, R; White, D & Rodrigue, G
Item Type: Refine your search to only Article
open access

Portent of Heine's Reciprocal Square Root Identity

Description: Precise efforts in theoretical astrophysics are needed to fully understand the mechanisms that govern the structure, stability, dynamics, formation, and evolution of differentially rotating stars. Direct computation of the physical attributes of a star can be facilitated by the use of highly compact azimuthal and separation angle Fourier formulations of the Green's functions for the linear partial differential equations of mathematical physics.
Date: January 13, 2003
Creator: Cohl, H W
Item Type: Refine your search to only Article
open access

The Autonomous Pathogen Detection System

Description: We developed, tested, and now operate a civilian biological defense capability that continuously monitors the air for biological threat agents. The Autonomous Pathogen Detection System (APDS) collects, prepares, reads, analyzes, and reports results of multiplexed immunoassays and multiplexed PCR assays using Luminex{copyright} xMAP technology and flow cytometer. The mission we conduct is particularly demanding: continuous monitoring, multiple threat agents, high sensitivity, challenging environ… more
Date: January 13, 2009
Creator: Dzenitis, J M & Makarewicz, A J
Item Type: Refine your search to only Article
open access

Characterizing the Nano and Micro Structure of Concrete toImprove its Durability

Description: New and advanced methodologies have been developed to characterize the nano and microstructure of cement paste and concrete exposed to aggressive environments. High resolution full-field soft X-ray imaging in the water window is providing new insight on the nano scale of the cement hydration process, which leads to a nano-optimization of cement-based systems. Hard X-ray microtomography images of ice inside cement paste and cracking caused by the alkali?silica reaction (ASR) enables three-dimens… more
Date: January 13, 2009
Creator: Monteiro, Paulo J. M.; Kirchheim, A. P.; Chae, S.; Fischer, Peter; MacDowell, Alastair A.; Schaible, Eirc et al.
Item Type: Refine your search to only Article
open access

Viable Supersymmetry and Leptogenesis with Anomaly Mediation

Description: The seesaw mechanism that explains the small neutrino masses comes naturally with supersymmetric (SUSY) grand unification and leptogenesis. However, the framework suffers from the SUSY flavor and CP problems, and has a severe cosmological gravitino problem. We propose anomaly mediation as a simple solution to all these problems, which is viable once supplemented by the D-terms for U(1)_Y and U(1)_B-L. Even though the right-handed neutrino mass explicitly breaks U(1)_B-L and hence reintroduces t… more
Date: January 13, 2005
Creator: Ibe, Masahiro; Kitano, Ryuichiro; Murayama, Hitoshi & Yanagida, Tsutomu
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open access

The New Minimal Standard Model

Description: We construct the New Minimal Standard Model that incorporates the new discoveries of physics beyond the Minimal Standard Model (MSM): Dark Energy, non-baryonic Dark Matter, neutrino masses, as well as baryon asymmetry and cosmic inflation, adopting the principle of minimal particle content and the most general renormalizable Lagrangian. We base the model purely on empirical facts rather than aesthetics. We need only six new degrees of freedom beyond the MSM. It is free from excessive flavor-cha… more
Date: January 13, 2005
Creator: Davoudiasl, Hooman; Kitano, Ryuichiro; Li, Tianjun & Murayama, Hitoshi
Item Type: Refine your search to only Article
open access

Pulse Radiolysis of Aqueous Thiocyanate Solution

Description: The pulse radiolysis of N2O saturated aqueous solutions of KSCN was studied under neutral pH conditions. The observed optical absorption spectrum of the SCN• radical in solution is more complex than previously reported, but it is in good agreement with that measured in the gas phase. Kinetic traces at 330 nm and 472 nm corresponding to SCN• and (SCN)2•¯, respectively, were fit using a Monte Carlo simulation kinetic model. The rate coefficient for the oxidation of SCN¯ ions by OH radicals, an im… more
Date: January 13, 2005
Creator: Milosavljevic, Bratoljub H. & LaVerne, Jay A.
Item Type: Refine your search to only Article
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