Now showing items 11-30 of 47

  • Effective diffusion in a stochastic velocity field 

    Careta i Pons, Agustí; Sagués Mestre, Francesc; Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria (Springer Verlag, 1993-04-01)
    Article
    Restricted access - publisher's policy
    Analytical results are derived for the effective dispersion of a passive scalar in a stochastic velocity field evolving in a fast time scale. These results are favorably compared with direct computer simulation of ...
  • Effects of domain morphology in phase-separation dynamics at low temperature. 

    Lacasta Palacio, Ana María; Sancho, Jose Maria; Hernández Machado, Aurora; Toral, Raul. (American Physical Society, 1993-09-01)
    Article
    Open Access
    We present numerical results of the deterministic Ginzburg-Landau equation with a concentration-dependent diffusion coefficient, for different values of the volume fraction phi of the minority component. The morphology of ...
  • Escape over a potential barrier driven by colored noise: large but finite correlation time 

    de la Rubia, Francisco Javier; Peacock-López, E.; Tsironis, G P; Lindenberg, Katja; Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria (1988)
    Article
    Open Access
    The recent theory of Tsironis and Grigolini for the mean first-passage time from one metastable state to another of a bistable potential for long correlation times of the noise is extended to large but finite correlation times.
  • Evaporation and coarsening dynamics with open boundaries 

    Lacasta Palacio, Ana María; Sagués Mestre, Francesc; Sancho, Jose Maria; Sokolov, Igor M. (Americah Physical Society, 1999-01-31)
    Article
    Open Access
    We present a study of the evaporation dynamics of a substance undergoing a coarsening process. The system is modeled by the Cahn-Hilliard equation with absorbing boundaries. We have found that the dynamics, although of ...
  • Exported oscillator competition: a concept to analyze complex rhythms 

    Lacasta Palacio, Ana María; Sancho, Jose Maria; Sagués Mestre, Francesc (American Physical Society, 2005)
    Article
    Open Access
    We study the interaction between two independent nonlinear oscillators competing through a neutral excitable element. The first oscillator, completely deterministic, acts as a normal pacemaker sending pulses to the neutral ...
  • External fluctuations in front propagation 

    Armero Rovira, J.; Sancho, Jose Maria; Casademunt, Jaume; Lacasta Palacio, Ana María; Ramírez de la Piscina Millán, Laureano; Sagués Mestre, Francesc (American Physical Society, 1996-04-01)
    Article
    Open Access
    We study the effects of external noise in a one-dimensional model of front propagation. Noise is introduced through the fluctuations of a control parameter leading to a multiplicative stochastic partial differential equation. ...
  • First-passage time in a bistable potential with colored noise 

    Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria; de la Rubia, Francisco Javier; Lindenberg, Katja; Tsironis, G P (1989-08-15)
    Article
    Open Access
    A precise digital simulation of a bistable system under the effect of colored noise is carried out. A set of data for the mean first-passage time is obtained. The results are interpreted and compared with presently available ...
  • First-passage times for a marginal state driven by colored noise 

    Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria (The American Physical Society, 1991-01-18)
    Article
    Open Access
    The dynamical process through a marginal state (saddle point) driven by colored noise is studied. For small correlation time of the noise, the mean first-passage time and its variance are calculated using standard methods. ...
  • Fluctuations in domain growth: Ginzburg-Landau equations with multiplicative noise 

    Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria; Hernández Machado, Aurora (The American Physical Society, 1993-07-01)
    Article
    Open Access
    Ginzburg-Landau equations with multiplicative noise are considered, to study the effects of fluctuations in domain growth. The equations are derived from a coarse-grained methodology and expressions for the resulting ...
  • From subdiffusion to superdiffusion of particles on solid surfaces 

    Lacasta Palacio, Ana María; Sancho, Jose Maria; Sokolov, Igor M.; Lindenberg, K. (American Physical Society, 2004-11-15)
    Article
    Open Access
    We present a numerical and partially analytical study of classical particles obeying a Langevin equation that describes diffusion on a surface modeled by a two dimensional potential. The potential may be either periodic ...
  • Front and domain growth in the presence of gravity. 

    Lacasta Palacio, Ana María; Hernández-Machado, Aurora; Sancho, Jose Maria (American Physical Society, 1993-10-01)
    Article
    Open Access
    Front and domain growth of a binary mixture in the presence of a gravitational field is studied. The interplay of bulk (and surface) diffusion mechanisms is analyzed. An equation for the evolution of interfaces is derived ...
  • Front propagation in spatially modulated media 

    Armero, J.; Lacasta Palacio, Ana María; Ramírez de la Piscina Millán, Laureano; Casademunt, Jaume; Sancho, Jose Maria; Sagués Mestre, Francesc (American Physical Society, 1997-09-01)
    Article
    Open Access
    A two-dimensional reaction-diffusion front which propagates in a modulated medium is studied. The modulation consists of a spatial variation of the local front velocity in the transverse direction to that of the ...
  • Generation of spatiotemporal colored noise 

    García Ojalvo, Jordi; Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria (American Physical Society, 1992-10-01)
    Article
    Open Access
    We develop an algorithm to simulate a Gaussian stochastic process that is non-δ-correlated in both space and time coordinates. The colored noise obeys a linear reaction-diffusion Langevin equation with Gaussian white noise. ...
  • Higher order colored noise effects in multivariable systems. 

    Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria (American Physical Society, 1988-06-01)
    Article
    Open Access
    We extend the partial resummation technique of Fokker-Planck terms for multivariable stochastic differential equations with colored noise. As an example, a model system of a Brownian particle with colored noise is studied. ...
  • Implementación de los métodos de Riks-Wempner, Batoz-Dhatt, Powell-Simons y otros en el programa de elementos finitos F.E.A.P 

    Sancho, Jose Maria; Ortiz, Jesús (2009-03-09T16:16:24Z)
    Article
    Open Access
    Los fundamentos teóricos del método de Riks y su utilidad para el paso de puntos límite en el análisis no lineal de estructuras, están actualmente bien establecidos, pero resta aún una importante labor de normalización y ...
  • Langevin dynamics of A+A reactions in one dimension 

    Sancho, Jose Maria; Romero, A. H.; Lacasta Palacio, Ana María; Lindenberg, Katja (IOP Publishing, 2007-02-28)
    Article
    Open Access
    We propose a set of Langevin equations of motion together with a reaction rule for the study of binary reactions. Our scheme is designed to address this problem for arbitrary friction ° and temperature T. It easily ...
  • Langevin equations with multiplicative noise: application to domain growth 

    Sancho, Jose Maria; Hernández-Machado, A.; Ramírez de la Piscina Millán, Laureano; Lacasta Palacio, Ana María (Jagiellonian University, Polish Academy of Arts and Sciences, 1993-05-01)
    Article
    Open Access
    Langevin Equations of Ginzburg--Landau form, with multiplicative noise, are proposed to study the effects of fluctuations in domain growth. These equations are derived from a coarse-grained methodology. The Cahn--Hiliard--Cook ...
  • Modelization of surface diffusion of a molecular dimer 

    Romero, A. H.; Lacasta Palacio, Ana María; Sancho, Jose Maria (American Physical Society, 2004-05-20)
    Article
    Open Access
    A simple model for a dimer molecular diffusion on a crystalline surface, as a function of temperature, is presented. The dimer is formed by two particles coupled by a quadratic potential. The dimer diffusion is modeled by ...
  • Numerical algorithm for Ginzburg-Landau equations with multiplicative noise: application to domain growth 

    Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria; Hernández Machado, Aurora (The American Physical Society, 1993-07-01)
    Article
    Open Access
    We consider stochastic partial differential equations with multiplicative noise. We derive an algorithm for the computer simulation of these equations. The algorithm is applied to study domain growth of a model with a ...
  • Numerical study of A+A -> 0 and A+B ->0 reactions with inertia 

    Romero, A. H.; Lacasta Palacio, Ana María; Sancho, Jose Maria; Lindenberg, Katja (American Institute of Physics, 2007-11-30)
    Article
    Open Access
    Using numerical methods we study the annihilation reactions A + A → 0 and A + B → 0 in one and two dimensions in the presence of inertial contributions to the motion of the particles. The particles move freely following ...