Browsing by Author "Goncalves, S"

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    Cellular automaton block model of traffic In a city
    (1997) Brunnet, LG; Goncalves, S
    We present a cellular automaton model of traffic in a city where cars sit between crossings so that they never block the transversal movements. They turn with probability gamma, 0 less than or equal to gamma less than or equal to 1. The model is presented in two variants depending on the direction of the flow on the different streets. We numerically find that the mean velocity of traffic continuously decreases with increasing concentration of cars. For a given concentration the mean velocity is minimum for gamma=0.5 in both variants of the model. Exact expressions for gamma=0, 0.5, 1 are found for an infinite city and a global picture emerges in terms of asymptotic order: local jam and fluctuations.
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    Molecular dynamics study of physisorbed xenon on Al(1 1 0)
    (1997) Goncalves, S; Ramirez, R; Kiwi, M
    The adsorption of Xe on the (1 1 0) face of an Al substrate is investigated by means of molecular dynamics. A thermodynamic transformation at constant temperature is studied as a function of the Lennard-Jones potential range parameter sigma(Xe-Al), for several sizes of the Xe island adsorbed on Al. This way a critical value of sigma(Xe-Al), for which the island undergoes a commensurate-incommensurate transition, is identified. The implications of our results are discussed in the context of experimental interpretation and compared with published Monte Carlo work on this system. (C) 1997 Published by Elsevier Science Ltd.
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    Non-universality of phase separation in two-dimensional critical binary-fluid mixtures
    (1997) Goncalves, S; Martinez, G; Iglesias, JR
    The domain growth in the late-time regime of phase-separating two-dimensional A-B critical fluid mixtures is investigated with molecular-dynamics simulations. Growth exponents are found to depend not only on temperature, as was previously shown, but also on the particular pair interaction potential. We study this dependence for two different molecular pair potentials with reduced strength among unequal particles and discuss possible mechanisms for the coarsening process as a function of temperature. At the low-temperature quenching regime the phase separation shows percolating patterns not previously reported, where a sequential aggregation of clusters gives rise to a possible multi-scaling behaviour.