124,001 research outputs found

    Multiple anode arc lamp system

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    A high-intensity xenon arc lamp having a plurality of separate anodes axially disposed in a symmetrical pattern which spaced a discharge gap from a common cathode is presented

    Indicator providing continuous indication of the presence of a specific pollutant in air

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    A continuous HCl in-air indicator was developed which consists of a tube-like element with an inlet end through which a continuous stream of air containing HCl enters. The air flows downstream from the inlet end and exits the element's outlet end. Positioned between the element's inlet and outlet ends are first and second spaced apart photoelectric units, which are preferably positioned adjacent the inlet and outlet ends, respectively. Ammonia gas is injected into the air, flowing through the element, at a position between the two photoelectric units. The ammonia gas reacts with the HCl in the air to form ammonium chloride particles. The difference between the outputs of the two photoelectric units is an indication of the amount of HCl in the air stream

    A note on Volterra integral equations and topological dynamics

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    Topological dynamics theory applied to nonlinear Volterra equation

    Optimal Energy Estimation in Path-Integral Monte Carlo Simulations

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    We investigate the properties of two standard energy estimators used in path-integral Monte Carlo simulations. By disentangling the variance of the estimators and their autocorrelation times we analyse the dependence of the performance on the update algorithm and present a detailed comparison of refined update schemes such as multigrid and staging techniques. We show that a proper combination of the two estimators leads to a further reduction of the statistical error of the estimated energy with respect to the better of the two without extra cost.Comment: 45 pp. LaTeX, 22 Postscript Figure

    Monte Carlo Study of the Phase Structure of Compact Polymer Chains

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    We study the phase behavior of single homopolymers in a simple hydrophobic/hydrophilic off-lattice model with sequence independent local interactions. The specific heat is, not unexpectedly, found to exhibit a pronounced peak well below the collapse temperature, signalling a possible low-temperature phase transition. The system size dependence at this maximum is investigated both with and without the local interactions, using chains with up to 50 monomers. The size dependence is found to be weak. The specific heat itself seems not to diverge. The homopolymer results are compared with those for two non-uniform sequences. Our calculations are performed using the methods of simulated and parallel tempering. The performances of these algorithms are discussed, based on careful tests for a small system.Comment: 13 pages LaTeX, 6 Postscript figures, References adde

    A short note on the presence of spurious states in finite basis approximations

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    The genesis of spurious solutions in finite basis approximations to operators which possess a continuum and a point spectrum is discussed and a simple solution for identifying these solutions is suggested
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