95,301 research outputs found

    Description of Charged Particle Pseudorapidity Distributions in Pb+Pb Collisions with Tsallis Thermodynamics

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    The centrality dependence of pseudorapidity distributions for charged particles produced in Au+Au collisions at sNN=130\sqrt{s_{NN}}=130 GeV and 200 GeV at RHIC, and in Pb+Pb collisions at sNN=2.76\sqrt{s_{NN}}=2.76 TeV at LHC are investigated in the fireball model, assuming that the rapidity axis is populated with fireballs following one distribution function. We assume that the particles in the fireball fulfill the Tsallis distribution. The theoretical results are compared with the experimental measurements and a good agreement is found. Using these results, the pseudorapidity distributions of charged particles produced in Pb+Pb central collisions at sNN=5.02\sqrt{s_{NN}}=5.02 TeV and 10 TeV are predicted.Comment: 9 pages, 8 figure

    Dynamic microscopic structures and dielectric response in the cubic-to-tetragonal phase transition for BaTiO3 studied by first-principles molecular dynamics simulation

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    The dynamic structures of the cubic and tetragonal phase in BaTiO3 and its dielectric response above the cubic-to-tetragonal phase transition temperature (Tp) are studied by first-principles molecular dynamics (MD) simulation. It's shown that the phase transition is due to the condensation of one of the transverse correlations. Calculation of the phonon properties for both the cubic and tetragonal phase shows a saturation of the soft mode frequency near 60 cm-1 near Tp and advocates its order-disorder nature. Our first-principles calculation leads directly to a two modes feature of the dielectric function above Tp [Phys. Rev. B 28, 6097 (1983)], which well explains the long time controversies between experiments and theories

    A novel dual-stator hybrid excited synchronous wind generator

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    This paper presents a novel dual-stator hybrid excited synchronous wind generator and describes its structural features and operation principle. The no-load magnetic fields with different field currents are computed by 3-D finite-element method. Static characteristics, including the flux-linkage and EMF waveforms of stator windings, and inductance waveforms of armature windings and field winding, are analyzed. The simulation results show that due to the dual-stator structure, the air-gap magnetic flux can be easily controlled, while the output voltage can be increased effectively. Tests are performed on the prototype machine to validate the predicted results, and an excellent agreement is obtained