19,486 research outputs found

    Properties of a magnetic superconductor with weak magnetization - application to ErNi2B2CErNi_2B_2C

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    Using a Ginsburg-Landau free energy functional, we study the HTH-T phase diagram of a weak magnetic superconductor, where the magnetization from the magnetic component is marginal in supporting a spontaneous vortex phase in absence of external magnetic field. In particular, the competition between the spiral state and spontaneous vortex phase is analysed. Our theory is applied to understand the magnetic properties of ErNi2B2CErNi_2B_2C.Comment: 13 pages, 4 postscript figure

    Finding Faces in Cluttered Scenes using Random Labeled Graph Matching

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    An algorithm for locating quasi-frontal views of human faces in cluttered scenes is presented. The algorithm works by coupling a set of local feature detectors with a statistical model of the mutual distances between facial features it is invariant with respect to translation, rotation (in the plane), and scale and can handle partial occlusions of the face. On a challenging database with complicated and varied backgrounds, the algorithm achieved a correct localization rate of 95% in images where the face appeared quasi-frontally

    The Radon Monitoring System in Daya Bay Reactor Neutrino Experiment

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    We developed a highly sensitive, reliable and portable automatic system (H3^{3}) to monitor the radon concentration of the underground experimental halls of the Daya Bay Reactor Neutrino Experiment. H3^{3} is able to measure radon concentration with a statistical error less than 10\% in a 1-hour measurement of dehumidified air (R.H. 5\% at 25^{\circ}C) with radon concentration as low as 50 Bq/m3^{3}. This is achieved by using a large radon progeny collection chamber, semiconductor α\alpha-particle detector with high energy resolution, improved electronics and software. The integrated radon monitoring system is highly customizable to operate in different run modes at scheduled times and can be controlled remotely to sample radon in ambient air or in water from the water pools where the antineutrino detectors are being housed. The radon monitoring system has been running in the three experimental halls of the Daya Bay Reactor Neutrino Experiment since November 2013

    Novel Phases and Finite-Size Scaling in Two-Species Asymmetric Diffusive Processes

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    We study a stochastic lattice gas of particles undergoing asymmetric diffusion in two dimensions. Transitions between a low-density uniform phase and high-density non-uniform phases characterized by localized or extended structure are found. We develop a mean-field theory which relates coarse-grained parameters to microscopic ones. Detailed predictions for finite-size (LL) scaling and density profiles agree excellently with simulations. Unusual large-LL behavior of the transition point parallel to that of self-organized sandpile models is found.Comment: 7 pages, plus 6 figures uuencoded, compressed and appended after source code, LATeX, to be published as a Phys. Rev. Let

    Heuristic derivation of continuum kinetic equations from microscopic dynamics

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    We present an approximate and heuristic scheme for the derivation of continuum kinetic equations from microscopic dynamics for stochastic, interacting systems. The method consists of a mean-field type, decoupled approximation of the master equation followed by the `naive' continuum limit. The Ising model and driven diffusive systems are used as illustrations. The equations derived are in agreement with other approaches, and consequences of the microscopic dependences of coarse-grained parameters compare favorably with exact or high-temperature expansions. The method is valuable when more systematic and rigorous approaches fail, and when microscopic inputs in the continuum theory are desirable.Comment: 7 pages, RevTeX, two-column, 4 PS figures include
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