Air cushioning with a lubrication/ inviscid balance

The air cushioning effect in the gap between an almost inviscid body of water and a nearby solid wall (or another body of water) is studied theoretically and is found to depend on predominantly lubricating forces in the air, in certain applications. The situation in which the density and viscosity in air are taken as small compared with those in water is investigated. In this situation potential-flow dynamics in the water couples with lubrication behaviour in the air, leading to a nonlinear integro-differential system for the evolution of the interface. The numerical values of the main parameters are investigated and indicate a wide range of practical applications. Specifically, the lubrication/inviscid balance holds for typical global Reynolds numbers below the order of the viscosity ratio divided by the cube of the density ratio, i.e. below about 10$^{7}$ in the case of air and water; for Reynolds numbers of that order the lubrication behaviour is replaced by an unsteady boundary-layer response, whereas above that order formally the response is totally inviscid. A variety of spatio-temporal flow solutions are presented for the lubrication/inviscid system and these all indicate a relatively rapid closure of the gap, in a common form which is analysed

Recent N^* Results From J/\psi Decays

Based on 7.8 million J/\psi events collected at BEPC, the events for J/\psi \to p\bar{p}\pi^0 and p\bar{p}\eta have been selected and reconstructed. Clear peaks are observed around 1480 MeV in p\pi^0 (\bar{p}\pi^0) invariant mass spectrum and near the threshold for $\eta$ production in p\eta(\bar{p}\eta) invariant mass spectrum. A partial wave analysis of J/\psi \to p\bar{p}\eta data has been performed. Two J^P={1/2}^- resonances are observed with mass and width (M, \Gamma) at (1540^{+15}_{-17}, 178^{+20}_{-22}) MeV and (1648^{+18}_{-16}, 150)MeV, and are considered to be the nucleon resonances S_{11}(1535) and S_{11}(1650) respectively.Comment: 4 pages, 4 figures, proceedings for Hadron9

Mass formulas and thermodynamic treatment in the mass-density-dependent model of strange quark matter

The previous treatments for strange quark matter in the quark mass-density-dependent model have unreasonable vacuum limits. We provide a method to obtain the quark mass parametrizations and give a self-consistent thermodynamic treatment which includes the MIT bag model as an extreme. In this treatment, strange quark matter in bulk still has the possibility of absolute stability. However, the lower density behavior of the sound velocity is opposite to previous findings.Comment: Formatted in REVTeX 3.1, 5 pages, 3 figures, to appear in PRC6

A Statistical Study on Photospheric Magnetic Nonpotentiality of Active Regions and Its Relationship with Flares during Solar Cycles 22-23

A statistical study is carried out on the photospheric magnetic nonpotentiality in solar active regions and its relationship with associated flares. We select 2173 photospheric vector magnetograms from 1106 active regions observed by the Solar Magnetic Field Telescope at Huairou Solar Observing Station, National Astronomical Observatories of China, in the period of 1988-2008, which covers most of the 22nd and 23rd solar cycles. We have computed the mean planar magnetic shear angle (\bar{\Delta\phi}), mean shear angle of the vector magnetic field (\bar{\Delta\psi}), mean absolute vertical current density (\bar{|J_{z}|}), mean absolute current helicity density (\bar{|h_{c}|}), absolute twist parameter (|\alpha_{av}|), mean free magnetic energy density (\bar{\rho_{free}}), effective distance of the longitudinal magnetic field (d_{E}), and modified effective distance (d_{Em}) of each photospheric vector magnetogram. Parameters \bar{|h_{c}|}, \bar{\rho_{free}}, and d_{Em} show higher correlation with the evolution of the solar cycle. The Pearson linear correlation coefficients between these three parameters and the yearly mean sunspot number are all larger than 0.59. Parameters \bar{\Delta\phi}, \bar{\Delta\psi}, \bar{|J_{z}|}, |\alpha_{av}|, and d_{E} show only weak correlations with the solar cycle, though the nonpotentiality and the complexity of active regions are greater in the activity maximum periods than in the minimum periods. All of the eight parameters show positive correlations with the flare productivity of active regions, and the combination of different nonpotentiality parameters may be effective in predicting the flaring probability of active regions.Comment: 20 pages, 5 figures, 4 tables, accepted for publication in Solar Physic

Some remarks on the angular momenta of galaxies, their clusters and superclusters

We discuss the relation between angular momenta and masses of galaxy structures base on the Li model of the universe with global rotation. In our previous paper (God{\l}owski et al 2002) it was shown that the model predicts the presence of a minimum in this relation. In the present paper we discuss observational evidence allowing us to verify this relation. We find null angular momentum J=0 for the masses corresponding to mass of galaxy grups and non-vanishing angular momenta for other galactic structures. We check these theoretical predictions analysing Tully's galaxy grups. The existing data comparing alignment in different galactic structure are consistent with obtained theoretical relation $J(M)$ if we interpret the groving alignment as the galactic increasing angular momenta in the galactic structure.Comment: 20 pages 1 figure. GRG accepte

Electronic Structures of Cu/S Co-doped/Anatase TiO 2 by First-principles

ABSTRACT The structural parameters, band structures and density of states of anatase TiO2 co-doped with Cu and S were calculated by first-principles based on the density functional theory. The results indicate that the volumes of the co-doped TiO2 increase due to the lattice distortion. The calculated X-ray diffraction pattern shows that the crystal phase of TiO2 is still kept as anatase after Cu and S co-doping. The band gap of TiO2 broadened when S substitutes for Ti or O along with Cu substitutes for Ti. The calculated partial density of states shows that the impurity energy levels mainly come from the Cu 3d and S 3p orbital. The calculated results may provide some theoretical foundations for the photocatalytic activity enhancement of TiO2 co-doped with Cu and S