Non-Universal Finite Size Effects with Universal Infinite-Size Free Energy for the α\alpha-XY model

We study finite size effects in a family of systems in which a parameter controls interaction-range. In the long-range regime where the infinite-size free energy is universal, we show that the finite size effects are not universal but depend on the interaction-range. The finite size effects are observed through discrepancies between time-averages of macroscopic variables in Hamiltonian dynamics and canonical averages of ones with infinite degrees of freedom. For a high energy regime, the relation to a pair of the discrepancies is theoretically predicted and numerically confirmed. We also numerically show that the finite-size effects of macroscopic variables in the canonical ensemble are close to ones in the dynamical systems.Comment: Proceedings of the workshop Comlexty and Nonextensivity - New Trends in Statistical Mechancs - (CN-Kyoto

A Discovery of a Peculiar Pulsar in the Small Magellanic Cloud

We report on a peculiar X-ray binary pulsar IKT1 = RXJ0047.3-7312 observed with XMM-Newton in Oct. 2000. The X-ray spectrum is described by a two-component spectrum. The hard component has a broken power-law with respective photon indices of 0.2 and 1.8, below and above the break energy at 5.8 keV. The soft component can be modeled by a blackbody of kT = 0.6 keV. The X-ray flux shows a gradual decrease and periodic variations of about 4000 s. The averaged flux in 0.7-10.0 keV is 2.9x10^-12 ergs/cm^2/s, which is ~10 times brighter than that in a ROSAT observation in Nov. 1999. In addition to the 4000-s variation, we found coherent pulsations of 263 +/- 1 s. These discoveries strengthen the Be/X-ray binary scenario proposed by the ROSAT and ASCA observations on this source, and confirm that most of the hard sources in the Small Magellanic Cloud are X-ray binary pulsars. A peculiar property of this XBP is that the coherent pulsations are found only in the soft component, and the folded light curve shows a flat top shape with a sharp dip. We discuss the nature of this XBP focusing on the peculiar soft component.Comment: 5 pages, 5figures, Accepted for publication in PAS

Sol-gel synthesis of molecular sieving silica membranes

Polymeric silica sol was synthesized by the acid catalyzed hydrolysis and condensation of tetra-ethyl-ortho-silicate. Calcined unsupported membranes made from this sol showed microporous nature. Supported membranes on alumina were prepared by dipping and calcining. Helium showed activated diffusion with an apparent activation energy of 17 kJ mol−1. H2 permeation was comparable to that of helium under identical conditions. N2, Ar, O2, C3H6, C3H8, n-C4H10 and i-C4H10 permeation values were extremely small and therefore difficult to fit appropriate diffusion models. At 303 K hydrocarbon permeation was about 2 times higher than that of N2, Ar or O2. permselectivity around 1000 and helium permeation in the order of 10−7–10−8 mol m−2 s−1 Pa−1 were measured in the temperature range of 303–460 K. Comparison of Eact, selectivity and He and N2 permeation of different samples evidenced the dependence of nitrogen flux on processing defects. Obviously permeation rate of nitrogen molecule was insignificant through majority pores of the membrane

Modeling the effect of 1 MeV electron irradiation on the performance of n(+)-p-p(+) silicon space solar cells

Energetic particles such as electrons and protons induce severe degradation on the performance of solar cells used to power satellites and space vehicles. This degradation is usually attributed to lattice damage in the active region of the solar cell. One of the phenomena observed in silicon solar cells exposed to 1 MeV electron irradiation is the anomalous degradation of the short circuit current. It initially decreases followed by a recovery before falling again with increasing electron fluence. This behavior is usually attributed to type conversion of the solar cell active region. The other figures of merit, on the other hand, decrease monotonically. In this work numerical simulator SCAPS (Solar Cell Capacitance Simulator) is used to elucidate this phenomenon. The current-voltage characteristics of a Si n+–p–p+ structure are calculated under air mass zero spectrum with the fluence of 1 MeV electrons as a variable parameter. The effect of irradiation on the solar cell is simulated by a set of defects of which the energy levels lie deep in energy gap of silicon (much larger than the characteristic thermal energy kT far from either the conduction or valence band). Although several types of deep levels are induced by irradiation including deep donors (exchange electrons mainly with the conduction band), deep acceptors (exchange electrons mainly with the valence band) and/or generation recombination centers (exchange electrons with both the conduction and valence bands), it was found that, only one of them (the shallowest donor) is responsible for the anomalous degradation of the short circuit current. It will be also shown, by calculating the free charge carrier profile in the active region, that this behavior is not related to type conversion but to a lateral widening of the space charge region