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Nonequilibrium fluctuations in shock compression of polycrystalline [alpha]-iron

Description: The existence of mesoscale stress and velocity fluctuation has been recognized by experimentalists and theoretical analysts. Good examples are stress fields around crack tips and in composite materials. However, the issue of heterogeneous and nonequilibrium shock-front dynamics on the grain scale has been largely ignored, in spite of the fact that they must strongly influence the processes such as shear banding, fracture, and phase transition occurring under the above conditions. These phenomen… more
Date: January 1, 2001
Creator: Horie, Y. (Yasuyuki) & Yano, K. (Kazushige)
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Partner: UNT Libraries Government Documents Department
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On magnetic fluctuation spectra in the solar wind and the influence of mode dispersion

Description: Magnetic fluctuation power spectra in the solar wind are commonly observed to have a power-law form with a spectral index s = 5/3 at frequencies lower than about 1 Hz. This characteristic feature of magnetic fluctuation spectra defines what is called the inertial range and may be described, in wavenumber space, by Kolmogorov diffusion. For higher frequencies, it has been suggested that collisionless damping of Alfven and magnetosonic waves leads to steeper power-laws; this regime is sometimes l… more
Date: January 1, 2001
Creator: Gary, S. Peter; Stawicki, O. (Olaf) & Li, H. (Hui)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Calibration of a gamma calibration well with an energy-compensated Geiger-Mueller (G-M) tube.

Description: A working-standard Radcal model 1515 radiation monitor with the 1800cc ion chamber was used previously at Los Alamos National Laboratory (LANL) to calibrate and perform routine QA checks on the low-level gamma well, which produces exposure rates in the range of 0.2 mR/h to 10 mR/h. During long integration times (e.g. 24-48 hrs) with the 1800 cc ion chamber, which were required to obtain the necessary precision, changes in temperature and pressure and fluctuations in the zero offset introduced e… more
Date: January 1, 2001
Creator: George, G. L. (Gerald L.); Seagraves, D. T. (David T.) & Valdez, D. T. (Darlene T.)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Experimental heat leak measurements on the APT 210 KW CW RF power coupler

Description: A cryogenic test rig was designed and fabricated to measure the heat leak from room temperature to 2 K from the Accelerator Production of Tritium (APT) 700 MHz, 210 kW continuous wave (CW) co-axial power coupler (PC). The outer conductor of the PC is stainless steel with 15 {micro}m copper film on the inside. The copper inner conductor operates at room temperature and contributes considerable infra-red radiation heat load to 2 K. Two thermal intercept heat exchangers cooled by supercritical hel… more
Date: January 1, 2001
Creator: Blumenfelda, P. E.; Prenger, F. Coyne; Kelley, J. P. (John Patrick); Currie, S. A. (Scott A.); Stewart, J. A. (James A.) & Waynert, J. A. (Joseph A.)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Single chain stochastic polymer modeling at high strain rates.

Description: Our goal is to develop constitutive relations for the behavior of a solid polymer during high-strain-rate deformations. In contrast to the classic thermodynamic techniques for deriving stress-strain response in static (equilibrium) circumstances, we employ a statistical-mechanics approach, in which we evolve a probability distribution function (PDF) for the velocity fluctuations of the repeating units of the chain. We use a Langevin description for the dynamics of a single repeating unit and a … more
Date: January 1, 2001
Creator: Harstad, E. N. (Eric N.); Harlow, Francis Harvey, & Schreyer, H. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Elastic properties of HMX.

Description: Atomistic molecular dynamics simulations have been used to calculate isothermal elastic properties for {beta}-, {alpha}-, and {delta}-HMX. The complete elastic tensor for each polymorph was determined at room temperature and pressure via analysis of microscopic strain fluctuations using formalism due to Rahman and Parrinello [J. Chem. Phys. 76,2662 (1982)]. Additionally, the isothermal compression curve was computed for {beta}-HMX for 0 {le} p {le} 10.6 GPa; the bulk modulus K and its pressure … more
Date: January 1, 2001
Creator: Sewell, T. D. (Thomas D.); Bedrov, D. (Dmitry); Menikoff, Ralph & Smith, G. D. (Grant D.)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Probing spatial correlations in the inhomogeneous glassy state of the cuprates by Cu NMR.

Description: We discuss the crossover of the form of the Cu NMR spin echo decay at the onset of Cu wipeout in lanthanum cuprates. Experimentally, the echo decay undergoes a crossover from Gaussian to exponential form below the temperature where the Cu NMR intensity drops. The wipeout and the change in behavior both arise because the nuclei experience spatially inhomogeneous spin fluctuations at low temperatures. We argue that regions where the spin fluctuations remain fast are localized on length scales of … more
Date: January 1, 2001
Creator: Curro, N. J. (Nicholas J.)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Fluctuation probes of quark deconfinement

Description: Fluctuations in the multiplicities and momentum distributions of particles emitted in relativistic heavy-ion collisions have been widely considered as probes of thermalization and the statistical nature of particle production in such reactions. The characteristic behavior of temperature and pion multiplicity fluctuations in the final state has been proposed as a tool for the measurement of the specific heat and, specifically, for the detection of a critical point in the nuclear matter phase dia… more
Date: June 20, 2001
Creator: Asakawa, M.; Heinz, U. & Muller, B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Effects of buoyancy on the flowfields of lean premixed turbulentv-flames

Description: Open laboratory turbulent flames used for investigating fundament flame turbulence interactions are greatly affected by buoyancy. Though much of our current knowledge is based on observations made in these open flames, the effects of buoyancy are usually not included in data interpretation, numerical analysis or theories. This inconsistency remains an obstacle to merging experimental observations and theoretical predictions. To better understanding the effects of buoyancy, our research focuses … more
Date: March 1, 2001
Creator: Cheng, R. K.; Bedat, B.; Yegian, D. T. & Greenberg, P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Advanced Computational Model for Three-Phase Slurry Reactors Progress Report: October 2001

Description: In the second year of the project, the Eulerian-Lagrangian formulation for analyzing three-phase slurry flows in a bubble column is further developed. The approach uses an Eulerian analysis of liquid flows in the bubble column, and makes use of the Lagrangian trajectory analysis for the bubbles and particle motions. An experimental set for studying a two-dimensional bubble column is also developed. The operation of the bubble column is being tested and diagnostic methodology for quantitative me… more
Date: October 1, 2001
Creator: Ahmadi, Goodarz
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Heavy Neutral Beam Probe for Edge Plasma Analysis in Tokamaks

Description: The Heavy Neutral Beam Probe (HNBP) developed initially with DOE funding under the Small Business Innovation Research (SBIR) program was installed on the Tokamak de Varennes (TdeV) at the CCFM. This diagnostic was designed to perform fundamental measurements of edge plasma properties. The hardware was capable of measuring electron density and potential profiles with high spatial and temporal resolution. Fluctuation spectra for these parameters were obtained with HNBP for transport studies.
Date: January 4, 2001
Creator: Castracane, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Potential oscillations and S-shaped polarization curve in the continuous electro-oxidation of CO on platinum single-crystal electrodes

Description: The occurrence of an S-shaped polarization curve in a simple model for the continuous electrochemical oxidation of CO on a platinum electrode is discussed. In the model, the S-shaped polarization curve is caused by the competitive Langmuir-Hinshelwood mechanism between surface-bonded CO and OH. The reaction is studied experimentally on single-crystal platinum rotating disk electrodes in perchloric and sulfuric acid solution, and it is shown that the voltammetry is in good agreement with the mod… more
Date: March 1, 2001
Creator: Koper, Marc T.M.; Schmidt, Thomas J.; Markovic, Nenad M. & Ross, Philip N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Thermodynamic Critical Field and Superconducting Fluctuation of Vortices for High Temperature Cuprate Superconductor: La-214

Description: Thermodynamics has been studied systematically for the high temperature cuprate superconductor La{sub 2-x}Sr{sub x}CuO{sub 4-{delta}}, La-214, in the entire superconductive region from strongly underdoped to strongly overdoped regimes. Magnetization studies with H{parallel}c have been made in order to investigate the changes in free energy of the system as the number of carriers is reduced. Above the superconducting transition temperature, the normal-state magnetization exhibits a two-dimension… more
Date: May 1, 2001
Creator: Huh, Yung Moo
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Edge Turbulence Imaging in the Alcator C-Mod Tokamak

Description: The 2-D radial vs. poloidal structure of edge turbulence in the Alcator C-Mod tokamak [I.H. Hutchinson, R. Boivin, P.T. Bonoli et al., Nuclear Fusion 41(2001) 1391] was measured using fast cameras and compared with 3-D numerical simulations of edge plasma turbulence. The main diagnostic is Gas Puff Imaging (GPI), in which the visible D(subscript alpha) emission from a localized D(subscript 2) gas puff is viewed along a local magnetic field line. The observed D(subscript alpha) fluctuations have… more
Date: November 26, 2001
Creator: Zweben, S. J.; Stotler, D. P.; Terry, J. L.; LaBombard, B.; Greenwald, M.; Muterspaugh, M. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Thermodynamic Critical Field and Superconducting Fluctuation of Vortices for High Temperature Cuprate Superconductor: La-214

Description: Thermodynamics has been studied systematically for the high temperature cuprate superconductor La{sub 2-x}Sr{sub x}CuO{sub 4-{delta}}, La-214, in the entire superconductive region from strongly underdoped to strongly overdoped regimes. Magnetization studies with H {parallel} c have been made in order to investigate the changes in free energy of the system as the number of carriers is reduced. Above the superconducting transition temperature, the normal-state magnetization exhibits a two-dimensi… more
Date: June 25, 2001
Creator: Finnemore, Douglas K.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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Scalar mesons in three-flavor linear sigma models

Description: The three flavor linear sigma model is studied in order to understand the role of possible light scalar mesons in the pi-pi, pi-K and pi-eta elastic scattering channels. The K-matrix prescription is used to unitarize tree-level amplitudes and, with a sufficiently general model, we obtain reasonable ts to the experimental data. The effect of unitarization is very important and leads to the emergence of a nonet of light scalars, with masses below 1 GeV. We compare with a scattering treatment usin… more
Date: September 2001
Creator: Black, Deirdre; Fariborz, Amir H.; Moussa, Sherif; Nasri, Salah & Schrechter, Joseph
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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HIGH PERFORMANCE PLASMAS ON THE NATIONAL SPHERICAL TORUS EXPERIMENT

Description: The National Spherical Torus Experiment has produced toroidal plasmas at low aspect ratio (A = R/a = 0.86d0.68m - 1.3, where R is the major radius and a is the minor radius of the torus) with plasma currents of 1.4MA. The rapid development of the machine has led to very exciting physics results during the first full year of physics operation. Pulse lengths in excess of 0.5s have been obtained with inductive current drive. Up to 4MW of High Harmonic Fast Wave (HHFW) heating power has been applie… more
Date: January 1, 2001
Creator: Gates, D. & Peng, Yueng Kay Martin
Item Type: Refine your search to only Book
Partner: UNT Libraries Government Documents Department
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Solar Power: Using Photovoltaics to Preserve California's Electricity Capacity Reserves

Description: The California Power Authority (CPA) is committed to increasing the use of renewable energy supplies--such as photovoltaics and wind--as a hedge against price fluctuations of electricity and natural gas. The CPA wants to own and operate an adequate supply of reserve generation that: - Can be deployed quickly in response to severe summer peak loads, unexpected loss of base and intermediate generation units, and failure of critical transmission facilities; - Will minimize the reliance on spot mar… more
Date: September 1, 2001
Creator: Herig, C..
Item Type: Refine your search to only Text
Partner: UNT Libraries Government Documents Department
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Phase equilibria in a system of 'breathing' molecules

Description: It is now well known that details in the intermolecular potential can significantly affect the qualitative features of a phase diagram where temperature is plotted against density for the coexistence curves among fluid and solid phases. While previous calculations of phase diagrams have assumed a time-invariant potential function, this report concerns the phase diagram for ''breathing'' molecules, i.e., molecules whose strength of intermolecular attraction fluctuates in time. Such fluctuations … more
Date: September 30, 2001
Creator: Wu, Jianzhong & Prausnitz, John
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Geographical and Temporal Dynamics of Chaetocnema Pulicaria and Their Role in Stewart's Disease of Corn in Iowa

Description: This thesis investigated the biology and importance of the corn flea beetle vector and its role in the Stewart's disease of corn pathosystem. This was accomplished by determining the number of corn flea beetle generations that occur in Iowa and by quantifying the proportions of those populations found to be infested with the causal agent of Stewart's disease, pantoea stewartii. In addition, a preliminary study was conducted to determine how soil temperature was influenced by air temperature and… more
Date: May 27, 2001
Creator: Esker, Paul David
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
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On the mass and salt budgets for a region of the continental shelf in the southern Mid-Atlantic Bight

Description: Two field studies were conducted across and along the continental shelf, one from February to May 1996 (deployment 1) and the other from July to October 1996 (deployment 2), in part to determine the mass and salt budgets of shelf water from south of Cape Henry to north of Cape Hatteras, the southernmost portion of the Mid-Atlantic Bight. The temporal means of current meter records indicated that most of the water enters the region across its northern boundary near the shelf break as part of a s… more
Date: December 1, 2001
Creator: Kim, Yoo Yin; Weatherly, Georges L. & Pietrafesa, Leonard J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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On the Choice of Method to Cancel 60 Hz Disturbances in Beam Position and Energy

Description: Because the voltage applied to magnets in accelerators is likely to be rectified, there can be 60 Hz related fluctuations in beam position and energy. Correcting such errors as well as other less repeatable errors can be done with combinations of feedback, feedforward, real time repetitive control, and batch update repetitive control. This paper studies how to mix these approaches for optimized performance. It is shown that use of feedback control can be counterproductive because of the waterbe… more
Date: June 1, 2001
Creator: Akogyeram, R.A.; Longman, R.W.; Hutton, Andrew & Juang, J.-N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Revised Theory of Transient Mass Fluctuations

Description: Several publications during the last 10 years by Woodward and colleagues have: (1) indicated a theory based on special relativity, that predicted transient mass fluctuations; (2) cited specific embodiments where a net average force would be present; (3) suggested a few ways that this theory might be tested in the laboratory; and (4) reported such test results incorporating these embodiments, which are interpreted to support theory (1) to (3) above. In this paper we show that: (1) the average fo… more
Date: September 4, 2001
Creator: Whealton, J.H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Measurement of Lower-hybrid Drift Turbulence in a Reconnecting Current Sheet

Description: We present a detailed study of fluctuations in a laboratory current sheet undergoing magnetic reconnection. The measurements reveal the presence of lower-hybrid-frequency range fluctuations on the edge of current sheets produced in the Magnetic Reconnection Experiment (MRX). The measured fluctuation characteristics are consistent with theoretical predictions for the lower-hybrid drift instability (LHDI). Our observations suggest that the LHDI does not provide any significant turbulent resistivi… more
Date: June 20, 2001
Creator: Carter, T.A.; Ji, H.; Trintchouk, F.; Yamada, M. & Kulsrud, R.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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