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Statistical fluctuations in heavy-ion collisions

Description: The relevance of the statistical equilibrium limit to the description of substantially relaxed degrees of freedom is discussed. Fluctuations are considered specifically in the following processes: the correlation between entrance-channel angular momentum and exit-channel kinetic energy; the sharing of the dissipated kinetic energy between the two fragments; the magnitude and the alignment of the fragment angular momentum including the effect of shell structure. It is found that statistical fluc… more
Date: February 1, 1982
Creator: Moretto, Luciano G.
Partner: UNT Libraries Government Documents Department
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Torque ripple in a Darrieus, vertical axis wind turbine

Description: Interaction between a steady wind and a rotating, Darrieus, vertical axis wind turbine produces time periodic aerodynamic loads which cause time dependent torque variations, referred to as torque ripple, to occur in the mechanical link between the turbine and the electrical generator. There is concern for the effect of torque ripple upon fatigue life of drive train components and upon power quality. An analytical solution characterizing the phenomenon of torque ripple has been obtained which is… more
Date: January 1, 1980
Creator: Reuter, R.C. Jr.
Partner: UNT Libraries Government Documents Department
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Pseudorapidity densities and fluctuations in central sup 32 S interactions at 200A GeV

Description: Observations of heavy ion interactions at the highest available accelerator energies provide essential information for the analysis and interpretation of cosmic ray interactions. We report on an experiment in which emulsion chamber detectors were exposed to beams of 200A GeV {sup 32}S ions at the CERN SPS. We present statistical features of pseudorapidity distributions from central collisions in the experimental sample and compare them with the predictions from the Lund Model (FRITIOF) which co… more
Date: January 1, 1990
Partner: UNT Libraries Government Documents Department
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Static and dynamic spin fluctuations in the spin glass doping regime in La sub 2-x Sr sub x CuO sub 4+y

Description: We review the results of neutron scattering studies of the static and dynamic spin fluctuations crystals of La{sub 2-x}Sr{sub x}CuO{sub 4+{delta}} in the doping regime intermediate between the Neel and superconducting regions. In this regime the in-plane resistance is linear in temperature down to {approximately}80 K with a crossover due to logarithmic conductance effects at lower temperatures. The static spin correlations are well-described by a simple model in which the inverse correlation le… more
Date: January 1, 1991
Creator: Birgeneau, R.J.; Belk, N.; Kastner, M.A.; Keimer, B. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Physics); Endoh, Y. (Tohoku Univ., Sendai (Japan). Dept. of Physics); Erwin, R.W. (National Inst. of Standards and Technology, Gaithersburg, MD (United States)) et al.
Partner: UNT Libraries Government Documents Department
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Phase space distribution of particles near an isolated difference resonance

Description: We have studied the phase space distribution of beam particles near an isolated difference resonance. The numerical simulation has shown that the distribution can quickly settle down to a final state if its initial state is Gaussian. The final state can be treated as a stationary state as long as the high order fluctuation can be neglected. From the Liouville equation, the emittances of beam particles are calculated approximately. There is a good agreement between analytical and numerical resul… more
Date: January 1, 1991
Creator: Shi, Jicong; Huang, Yunxiang & Ohnuma, Shoroku.
Partner: UNT Libraries Government Documents Department
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Role of rotational degrees of freedom in heavy-ion collisions

Description: The degrees of freedom affected by the angular momentum are identified. The relevance of the equilibrium fluctuations in a diffusive evolution of the system is discussed. The statistical limit is described and chosen as a reference for comparing with experiment. The rigid rotation regime is shown to be reached in a variety of reactions. The fragment spin alignment is measured from ..gamma..-ray multiplicities and anisotropies as well as from sequential fission angular distributions. Good agreem… more
Date: April 1, 1982
Creator: Moretto, Luciano G.
Partner: UNT Libraries Government Documents Department
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Thermal and quantal isospin and spin fluctuations in heavy ion reactions

Description: The isobaric charge distributions are discussed in terms of quantal and classical isospin fluctuations. The roles of mass asymmetry and of the higher giant isovector modes are treated within the framework of a cylinder model that is worked out exactly. Spin fluctuations are considered first in terms of quantal fluctuations in a cylinder model and second in terms of thermal fluctuations in a two-sphere model. The results are applied to the calculation of in- and out-of-plane angular distribution… more
Date: January 1, 1980
Creator: Moretto, Luciano G.
Partner: UNT Libraries Government Documents Department
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On the causes of compositional order in the Ni sub c Pt sub (1-c) alloys

Description: We review, briefly, the arguments which gave rise to the current controversy concerning the origin of compositional order in Ni{sub c}Pt{sub 1-c} alloys. We note that strain fluctuations play an important role in determining the state of compositional order in this system and outline a theoretical framework that takes account of them. 29 refs., 4 figs.
Date: January 1, 1991
Creator: Gyorffy, B.L. (Bristol Univ. (United Kingdom). H.H. Wills Physics Lab.); Pinski, F.J. (Cincinnati Univ., OH (United States). Dept. of Physics); Ginatempo, B. (Messina Univ. (Italy). Ist. di Fisica Teorica); Johnson, D.D. (Sandia National Labs., Albuquerque, NM (United States)); Staunton, J.B. (Warwick Univ., Coventry (United Kingdom). Dept. of Physics); Shelton, W.A. et al.
Partner: UNT Libraries Government Documents Department
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Overview of recent results from the Advanced Toroidal Facility

Description: An overview of recent experimental results from the Advanced Toroidal Facility (ATF) is presented. Beam-heated plasmas with {bar n}{sub e} of 10{sup 20} m{sup {minus}3} and {tau}{sub E}{asterisk} of {approx}20 ms have been achieved. Thermal collapse of the plasmas is mitigated by wall conditioning and particle fueling. Confinement time scales positively with density and magnetic field, offsetting deterioration with power. Results fit the LHD scaling and the drift wave turbulence scaling. Bootst… more
Date: January 1, 1989
Creator: Anabitarte, E.; Hidalgo-Vera, C. (Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Madrid (Spain)); Anderson, F. S. B. (Wisconsin Univ., Madison, WI (USA)); Bell, G. L.; Gandy, R. F. (Auburn Univ., AL (USA)); Bell, J. D. et al.
Partner: UNT Libraries Government Documents Department
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Longitudinal spin fluctuations in nickel

Description: The longitudinal and transverse spin fluctuations in Ni have been measured below {Tc} by means of polarized neutron scattering in the momentum range 0.06 < q < 0.18 {angstrom}{sup -1}. In transverse scans spin wave peaks at E{sub q} = Dq{sup 2} appear as expected from early measurements performed with unpolarized neutrons. The longitudinal magnetic scattering {sub {chi}L}(q, E), on the other hand, is quasielastic without any signature of inelastic peaks near E{sub q}. The q and T dependences of… more
Date: October 10, 1989
Creator: Boeni, P.; Martinez, J. L. & Tranquada, J. M.
Partner: UNT Libraries Government Documents Department
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The fast simulation of electromagnetic and hadronic showers

Description: A program for the fast simulation of electromagnetic and hadronic showers using parameterizations for the longitudinal and lateral profile is described. The fluctuations and correlations of the parameters are taken into account in a consistent way. Comparisons with data over a wide energy range are made. 15 refs., 17 figs.
Date: October 1, 1989
Creator: Grindhammer, G.; Rudowicz, M.; Peters, S. (Stanford Linear Accelerator Center, Menlo Park, CA (USA) & Max-Planck-Institut fuer Physik und Astrophysik, Muenchen (Germany, F.R.). Werner-Heisenberg-Inst. fuer Physik)
Partner: UNT Libraries Government Documents Department
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Low frequency noise in freely suspended tin films at the superconducting transition. [Spectral density]

Description: The spectral density, S/sub v/(f), of the voltage noise across 1-D current-biased tin films has been measured at the superconducting transition. Each film was freely suspended between two thermal clamps a distance L apart in a vacuum can. A thin layer of lead was evaporated on the outer portion of the films to leave an uncoated middle region of length l. S/sub v/(f) was flat at frequencies below f/sub L/ approximately D/L/sup 2/, where D is the thermal diffusivity. At frequencies between f/sub … more
Date: July 1, 1977
Creator: Ketchen, M.B. & Clarke, J.
Partner: UNT Libraries Government Documents Department
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Plasma turbulence calculations on supercomputers

Description: This report discusses using supercomputers to calculate the fluctuation in plasma parameters in magnetic confinement devices. (LSP)
Date: January 1, 1991
Creator: Carreras, B. A.; Charlton, L. A.; Dominguez, N.; Drake, J. B.; Garcia, L.; Leboeuf, J. N. et al.
Partner: UNT Libraries Government Documents Department
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Reservoir response to tidal and barometric effects

Description: Solid earth tidal strain and surface loading due to fluctuations in barometric pressure have the effect, although extremely minute, of dilating or contracting the effective pore volume in a porous reservoir. If a well intersects the formation, the change in pore pressure can be measured with sensitive quartz pressure gauges. Mathematical models of the relevant fluid dynamics of the well-reservoir system have been generated and tested against conventional well pumping results or core data at the… more
Date: May 29, 1980
Creator: Hanson, J.M.
Partner: UNT Libraries Government Documents Department
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Effects of (. cap alpha. ,n) contaminants and sample multiplication on statistical neutron correlation measurements

Description: The complete formalism for the use of statistical neutron fluctuation measurements for the nondestructive assay of fissionable materials has been developed. This formalism includes the effect of detector deadtime, neutron multiplicity, random neutron pulse contributions from (..cap alpha..,n) contaminants in the sample, and the sample multiplication of both fission-related and background neutrons.
Date: January 1, 1980
Creator: Dowdy, E. J.; Hansen, G. E.; Robba, A. A. & Pratt, J. C.
Partner: UNT Libraries Government Documents Department
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Theory and Fluid Simulations of Boundary Plasma Fluctuations

Description: Theoretical and computational investigations are presented of boundary plasma microturbulence that take into account important effects of the geometry of diverted tokamaks--in particular, the effect of x-point magnetic shear and the termination of field lines on divertor plates. We first generalize our previous 'heuristic boundary condition' which describes, in a lumped model, the closure of currents in the vicinity of the x-point region to encompass three current-closure mechanisms. We then us… more
Date: January 9, 2007
Creator: Cohen, R. H.; LaBombard, B.; LoDestro, L. L.; Rognlien, T. D.; Ryutov, D. D.; Terry, J. L. et al.
Partner: UNT Libraries Government Documents Department
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Beyond Boltzmann-Gibbs statistics: Maximum entropy hyperensemblesout-of-equilibrium

Description: What is the best description that we can construct of athermodynamic system that is not in equilibrium, given only one, or afew, extra parameters over and above those needed for a description ofthe same system at equilibrium? Here, we argue the most appropriateadditional parameter is the non-equilibrium entropy of the system, andthat we should not attempt to estimate the probability distribution ofthe system, but rather the metaprobability (or hyperensemble) that thesystem is described by a par… more
Date: February 23, 2006
Creator: Crooks, Gavin E.
Partner: UNT Libraries Government Documents Department
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Modeling the Benefits of Storage Technologies to Wind Power

Description: Rapid expansion of wind power in the electricity sector is raising questions about how wind resource variability might affect the capacity value of wind farms at high levels of penetration. Electricity storage, with the capability to shift wind energy from periods of low demand to peak times and to smooth fluctuations in output, may have a role in bolstering the value of wind power at levels of penetration envisioned by a new Department of Energy report ('20% Wind by 2030, Increasing Wind Energ… more
Date: June 1, 2008
Creator: Sullivan, P.; Short, W. & Blair, N.
Partner: UNT Libraries Government Documents Department
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Modeling Microbunching from Shot Noise Using Vlasov Solvers

Description: Unlike macroparticle simulations, which are sensitive to unphysical statistical fluctuations when the number of macroparticles is smaller than the bunch population, direct methods for solving the Vlasov equation are free from sampling noise and are ideally suited for studying microbunching instabilities evolving from shot noise. We review a 2D (longitudinal dynamics) Vlasov solver we have recently developed to study the microbunching instability in the beam delivery systems for x-ray FELs and p… more
Date: May 1, 2008
Creator: Venturini, Marco; Venturini, Marco & Zholents, Alexander
Partner: UNT Libraries Government Documents Department
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Experimental characterization of initial conditions and spatio-temporal evolution of a small Atwood number Rayleigh-Taylor mixing layer

Description: The initial multi-mode interfacial velocity and density perturbations present at the onset of a small Atwood number, incompressible, miscible, Rayleigh-Taylor instability-driven mixing layer have been quantified using a combination of experimental techniques. The streamwise interfacial and spanwise interfacial perturbations were measured using high-resolution thermocouples and planar laser-induced fluorescence (PLIF), respectively. The initial multi-mode streamwise velocity perturbations at the… more
Date: September 26, 2005
Creator: Mueschke, N J; Andrews, M J & Schilling, O
Partner: UNT Libraries Government Documents Department
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Empirical Analysis of the Spot Market Implications ofPrice-Responsive Demand

Description: Regardless of the form of restructuring, deregulatedelectricity industries share one common feature: the absence of anysignificant, rapid demand-side response to the wholesale (or, spotmarket) price. For a variety of reasons, most electricity consumers stillpay an average cost based regulated retail tariff held over from the eraof vertical integration, even as the retailers themselves are oftenforced to purchase electricity at volatile wholesale prices set in openmarkets. This results in consid… more
Date: August 1, 2005
Creator: Siddiqui, Afzal S.; Bartholomew, Emily S. & Marnay, Chris
Partner: UNT Libraries Government Documents Department
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Metal particles produced by laser ablation for ICP-MSmeasurements

Description: Pulsed laser ablation (266nm) was used to generate metal particles of Zn and Al alloys using femtosecond (150 fs) and nanosecond (4 ns) laser pulses with identical fluences of 50 J cm{sup -2}. Characterization of particles and correlation with Inductively Coupled Plasma Mass Spectrometer (ICP-MS) performance was investigated. Particles produced by nanosecond laser ablation were mainly primary particles with irregular shape and hard agglomerates (without internal voids). Particles produced by fe… more
Date: June 1, 2007
Creator: Gonzalez, Jhanis J.; Liu, Chunyi; Wen, Sy-Bor; Mao, Xianglei & Russo, Richard E.
Partner: UNT Libraries Government Documents Department
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STOUT SMEARING FOR TWISTED FERMIONS.

Description: The effect of Stout smearing is investigated in numerical simulations with twisted mass Wilson quarks. The phase transition near zero quark mass is studied on 12{sup 3} x 24, 16{sup 3} x 32 and 24{sup 3} x 48 lattices at lattice spacings a {approx_equal} 0.1-0.125 fm. The phase structure of Wilson fermions with twisted mass ({mu}) has been investigated in [1,2]. As it is explained there, the observed first order phase transition limits the minimal pion mass which can be reached in simulations a… more
Date: July 30, 2007
Creator: SCHOLZ,W.; JANSEN, K.; McNEILE, C.; MONTVAY, I.; RICHARDS, C.; URBACH, C. et al.
Partner: UNT Libraries Government Documents Department
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