44 Matching Results

Search Results

Results: 1 - 24 next
open access

Beam Simulations for IRE and Driver - Status and Strategy

Description: The methods and codes employed in the U.S. Heavy Ion Fusion program to simulate the beams in an Integrated Research Experiments (IRE) facility and a fusion driver are presented in overview. A new family of models incorporating accelerating module impedance, multi-beam, and self-magnetic effects is described, and initial WARP3d particle simulations of beams using these models are presented. Finally, plans for streamlining the machine-design simulation sequence, and for simulating beam dynamics f… more
Date: March 13, 2001
Creator: Friedman, A; Grote, D P & Lee, E P
Partner: UNT Libraries Government Documents Department
open access

Comparision of Limit Load Solutions with Results of a Collapse Tests of Perforated Plates with a Triangular Penetration Pattern

Description: Limit load solutions obtained by elastic-perfectly plastic finite element analysis (EPP-FEA) are compared to results of tests of low-alloy steel perforated plate geometries loaded to full plastic collapse. Results are given for two plastic-collapse tests of flat circular disks with circular penetrations arranged in a triangular pattern and drilled normal to the surface of the plate. The ligament efficiency (minimum distance between holes divided by the distance between the centers of the holes)… more
Date: December 13, 2001
Creator: Jones, D.P. & Gordon, J.L.
Partner: UNT Libraries Government Documents Department
open access

C{sub 2}D{sub 5}I dissociation and D + CH{sub 3} {yields} CH{sub 2}D + H at high temperature : implications to the high pressure rate constant for CH{sub 4} dissociation.

Description: The shock tube technique with H- and D-atom atomic resonance absorption spectrometry (ARAS) detection has been used to study the thermal decomposition of C{sub 2}D{sub 5}I and the reaction, CH{sub 3} + D'' CH{sub 2}D + H, (1) over the temperature ranges, 924-1370 K and 1294-1753 K, respectively. First-order rate constants for the thermal decomposition of C{sub 2}D{sub 5}I can be expressed by the Arrhenius equation, logk{sub C2D5I} = (10.397 {+-} 0.297) - (7700 {+-} 334 K)/T, giving k{sub C2D5I}… more
Date: December 13, 2001
Creator: Su, M.-C. & Michael, J. V.
Partner: UNT Libraries Government Documents Department
open access

Reimplementing the EPICS static database access library.

Description: The Static Database Access library was first introduced in EPICS (Experimental Physics and Industrial Control System) Release 3.11 in 1994. It provides an application program interface (API) for database configuration tools written in C to manipulate database record definitions and is used for various tasks within the core EPICS software. This paper describes the structure of a replacement for the original library that adds a native C++ API and will make some future enhancements to EPICS signif… more
Date: November 13, 2001
Creator: Johnson, A. N. & Kraimer, M. R.
Partner: UNT Libraries Government Documents Department
open access

Radio AGN Surveys

Description: We present a short overview of radio surveys for AGN, including the ''complete'' flux limited surveys and ''filtered'' surveys. We also describe our ultra-steep spectrum search for the highest redshift radio galaxies, and our follow-up VLA and ATCA observations of the most distant (z = 5.19) and the most luminous z < 2 radio galaxy known.
Date: November 13, 2001
Creator: De Breuck, C.; van Breugel, W.; Rottgering, H. & Carilli, C. L.
Partner: UNT Libraries Government Documents Department
open access

Superlubricity and wearless sliding in diamondlike carbon films.

Description: Diamondlike carbon (DLC) films have attracted great interest in recent years mainly because of their unusual optical, electrical, mechanical, and tribological properties. Such properties are currently being exploited for a wide range of engineering applications including magnetic hard disks, gears, sliding and roller bearings, scratch resistant glasses, biomedical implants, etc. Systematic studies on carbon-based materials in our laboratory have led to the development of a new class of amorphou… more
Date: December 13, 2001
Creator: Erdemir, A.
Partner: UNT Libraries Government Documents Department
open access

["A Question of Loyalty" article, March 13, 2001]

Description: An article, written by Chris Bull for the LGBT magazine "The Advocate", that covers the Republican Unity Coalition, Log Cabin Republicans, and their members' responses to the new Bush administration. On the second page is an advertisement for a new movie.
Date: March 13, 2001
Creator: Bull, Chris
Partner: UNT Libraries Special Collections
open access

EIGER: Electromagnetic Interactions GEneRalized

Description: The EIGER (Electromagnetic Interactions Generalized) modeling suite is a joint development activity by the Lawrence Livermore National Lab, Sandia National Labs, the University of Houston, and the Navy (Space and Naval Warfare Systems Center-San Diego). The effort endeavors to bring the next generation of hybrid, higher-order, full-wave analysis methods into a single integrated framework. The tools are based upon frequency-domain solutions of Maxwell's equations to model scattering and radiatio… more
Date: June 13, 2001
Creator: Champagne, N J; Sharpe, R M & Rockway, J W
Partner: UNT Libraries Government Documents Department
open access

Sustainment of Spheromak Pasmas in SSPX

Description: SSPX (Sustained Spheromak Physics eXperiment) was constructed to investigate the key physics issues of buildup and sustainment of spheromak plasmas with elevated electron temperature. Long pulse buildup to high magnetic field and temperature, at modest gun current, may point the way to a potentially simpler and more compact fusion reactor. Reported here are T{sub e} measurements in new magnetic flux geometries, results from sustainment experiments with {approx}1ms pulses, and power balance mode… more
Date: June 13, 2001
Creator: Stallard, B. W.; Hill, D. N.; Holcomb, C.; Hooper, E. B.; McLean, H. S.; Wood, R. D. et al.
Partner: UNT Libraries Government Documents Department
open access

Toward Robust Climate Baselining: Objective Assessment of Climate Change Using Widely Distributed Miniaturized Sensors for Accurate World-Wide Geophysical Measurements

Description: A gap-free, world-wide, ocean-, atmosphere-, and land surface-spanning geophysical data-set of three decades time-duration containing the full set of geophysical parameters characterizing global weather is the scientific perquisite for defining the climate; the generally-accepted definition in the meteorological community is that climate is the 30-year running-average of weather. Until such a tridecadal climate base line exists, climate change discussions inevitably will have a semi-speculative… more
Date: November 13, 2001
Creator: Teller, E.; Leith, C.; Canavan, G.; Marion, J. & Wood, L.
Partner: UNT Libraries Government Documents Department
open access

Investigations on 10-Hz sub-Joule fs-Laser Pumped Neon- and Nickel-Like X-Ray Lasers

Description: Experimental investigations on the conditions to achieve transient gain in neon-like Ti and nickel-like molybdenum XUV laser pumped by a 10-HZ sub-Joule femtosecond laser are presented. The 4d-4p (J = 0-1) {lambda} = 18.9 nm and 4f-4d (J = 1-11) {lambda} = 22.6 nm lines in Ni-like Mo as well as the 3p-3s (J = 0-1) {lambda} = 32.6 nm line in neon-like titanium have been observed. The Ni-like laser lines show a threshold behavior with respect to the pump irradiance as they appear only above 10{su… more
Date: August 13, 2001
Creator: Tommasini, R; Nilsen, J & Fill, E E
Partner: UNT Libraries Government Documents Department
open access

Theorectical Studies of Excitation in Low-Energy Electron-Polyatomic Molecule Collisions

Description: This paper focuses on the channeling of energy from electronic to nuclear degrees of freedom in electron-polyatomic molecule collisions. We examine the feasibility of attacking the full scattering problem, both the fixed-nuclei electronic problem and the post-collision nuclear dynamics, entirely from first principles. The electron-CO{sub 2} system is presented as an example. We study resonant vibrational excitation, showing how a6 initio, fixed-nuclei electronic cross sections can provide the n… more
Date: August 13, 2001
Creator: Rescigno, T N; McCurdy, C W; Isaacs, W A; Orel, A E & Meyer, H D
Partner: UNT Libraries Government Documents Department
open access

Test Results for a Reciprocating Pump Powered by Decomposed Hydrogen

Description: A four-chamber piston pump has been tested in several evolving configurations. A significant improvement over an earlier hyadrazine pump is the elimination of warm gas leakage in the powerhead. This has been achieved through the used of soft seals for the power piston and intake-exhaust valves, with gas temperatures approaching 800 K (980 F). The pumped fluid serves as a coolant, and the cylinder walls and heads are made of aluminum for high thermal conductivity, low mass, and affordability.
Date: June 13, 2001
Creator: Whitehead, J C
Partner: UNT Libraries Government Documents Department
open access

Photoemission and Photoabsorption Investigation of the Electronic Structure of Ytterbium Doped Strontium Fluoroapatite

Description: X-ray photoemission and x-ray photoabsorption were used to study the composition and the electronic structure of ytterbium doped strontium fluoroapatite (Yb:S-FAP). High resolution photoemission measurements on the valence band electronic structure was used to evaluate the density of occupied states of this fluoroapatite. Element specific density of unoccupied electronic states in Yb:S-FAP were probed by x-ray absorption spectroscopy (XAS) at the Yb 4d (N{sub 4,5}-edge), Sr 3d (M{sub 4,5}-edge)… more
Date: July 13, 2001
Creator: Nelson, A J; van Buuren, T; Bostedt, C; Schaffers, K I & Terminello, L
Partner: UNT Libraries Government Documents Department
open access

Long Range Weather Prediction III: Miniaturized Distributed Sensors for Global Atmospheric Measurements

Description: We continue consideration of ways-and-means for creating, in an evolutionary, ever-more-powerful manner, a continually-updated data-base of salient atmospheric properties sufficient for finite differenced integration-based, high-fidelity weather prediction over intervals of 2-3 weeks, leveraging the 10{sup 14} FLOPS digital computing systems now coming into existence. A constellation comprised of 10{sup 6}-10{sup 9} small atmospheric sampling systems--high-tech superpressure balloons carrying e… more
Date: November 13, 2001
Creator: Teller, E.; Leith, C.; Canavan, G. & Wood, L.
Partner: UNT Libraries Government Documents Department
open access

Detailed Chemical Kinetic Reaction Mechanisms for Incineration of Organophosphorus and Fluoro-Organophosphorus Compounds

Description: A detailed chemical kinetic reaction mechanism is developed to describe incineration of the chemical warfare nerve agent sarin (GB), based on commonly used principles of bond additivity and hierarchical reaction mechanisms. The mechanism is based on previous kinetic models of organophosphorus compounds such as TMP, DMMP and DIMP that are often used as surrogates to predict incineration of GB. Kinetic models of the three surrogates and GB are then used to predict their consumption in a perfectly… more
Date: December 13, 2001
Creator: Glaude, P A; Melius, C; Pitz, W J & Westbrook, C K
Partner: UNT Libraries Government Documents Department
open access

Concurrent Multiscale Modeling of Embedded Nanomechanics

Description: We discuss concurrent multiscale simulations of dynamic and temperature-dependent processes found in nanomechanical systems coupled to larger scale surroundings. We focus on the behavior of sub-micron Micro-Electro-Mechanical Systems (MEMS), especially micro-resonators. The coupling of length scales methodology we have developed for MEMS employs an atomistic description of small but key regions of the system, consisting of millions of atoms, coupled concurrently to a finite element model of the… more
Date: April 13, 2001
Creator: Rudd, R E
Partner: UNT Libraries Government Documents Department
open access

X-ray Optics and Diagnostics for the First Experiments on the Linac Coherent Light Source

Description: The Linac Coherent Light Source (LCLS) is a 1.5 to 15 {angstrom}-wavelength free-electron laser (FEL), currently proposed for the Stanford Linear Accelerator Center (SLAC). The photon output consists of high brightness, transversely coherent pulses with duration < 300 fs, together with a broad spontaneous spectrum with total power comparable to the coherent output. The output fluence, and pulse duration, pose special challenges for optical component and diagnostic designs. We discuss some of… more
Date: June 13, 2001
Creator: Wootton, A.; Arthur, J.; Barbee, T.; Bionta, R.; London, R.; Park, H. S. et al.
Partner: UNT Libraries Government Documents Department
open access

Resolving the mystery of prompt CO{sub 2} : the HCCO + 0{sub 2} reaction.

Description: The reaction of methyl radicals with hydrogen atoms is studied with a combination of ab initio quantum chemistry, variational transition state theory, and classical trajectory simulations. The interaction between the two radicals, including the umbrella mode of the methyl radical, is examined at the CAS+1+2 level using an augmented correlation consistent polarized valence triple zeta basis set. The implementation of an analytic representation of the ab initio data within variable reaction coord… more
Date: December 13, 2001
Creator: Klippenstein, S.; Miller, J. & Harding, L.
Partner: UNT Libraries Government Documents Department
open access

Validation of Two CFD Urban Dispersion Models using High Resolution Wind Tunnel Data

Description: Numerical modeling of air flow and pollutant dispersion around buildings in the urban environment is a challenging task due to the geometrical variations of buildings and the extremely complex flow created by such surface-mounted obstacles. Building-scale air flows inevitably involve flow impingement, stagnation, separation, a multiple vortex system, and jetting effects in street canyons. Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL) have developed two … more
Date: July 13, 2001
Creator: Chan, S; Stevens, D E & Smith, W. S.
Partner: UNT Libraries Government Documents Department
open access

Chemistry and Physics Challenges in Spallation Neutron Source Safety Analyses

Description: The SNS is a Department of Energy (DOE) research facility under construction near Oak Ridge, Tennessee. The SNS includes a 300-m long, 1 GeV, 2 MW, linear accelerator that produces neutrons by collisions of high-energy protons with mercury target nuclei. The mercury target atoms are in a circulating mercury loop that is water-cooled. The mercury loop operates at a nominal average temperature of 75 C (60 C nominal cold leg temperature and 90 C nominal hot leg temperature). The overall target sys… more
Date: June 13, 2001
Creator: Lowrie, RR
Partner: UNT Libraries Government Documents Department
Back to Top of Screen