Browsing by Author "Sancho, Jose Maria"

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, 19930401)
Article
Restricted access  publisher's policyAnalytical 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 phaseseparation dynamics at low temperature.
Lacasta Palacio, Ana María; Sancho, Jose Maria; Hernández Machado, Aurora; Toral, Raul. (American Physical Society, 19930901)
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Open AccessWe present numerical results of the deterministic GinzburgLandau equation with a concentrationdependent 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; PeacockLópez, E.; Tsironis, G P; Lindenberg, Katja; Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria (1988)
Article
Open AccessThe recent theory of Tsironis and Grigolini for the mean firstpassage 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, 19990131)
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Open AccessWe present a study of the evaporation dynamics of a substance undergoing a coarsening process. The system is modeled by the CahnHilliard 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)
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Open AccessWe 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, 19960401)
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Open AccessWe study the effects of external noise in a onedimensional model of front propagation. Noise is introduced through the fluctuations of a control parameter leading to a multiplicative stochastic partial differential equation. ... 
Firstpassage 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 (19890815)
Article
Open AccessA precise digital simulation of a bistable system under the effect of colored noise is carried out. A set of data for the mean firstpassage time is obtained. The results are interpreted and compared with presently available ... 
Firstpassage times for a marginal state driven by colored noise
Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria (The American Physical Society, 19910118)
Article
Open AccessThe dynamical process through a marginal state (saddle point) driven by colored noise is studied. For small correlation time of the noise, the mean firstpassage time and its variance are calculated using standard methods. ... 
Fluctuations in domain growth: GinzburgLandau equations with multiplicative noise
Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria; Hernández Machado, Aurora (The American Physical Society, 19930701)
Article
Open AccessGinzburgLandau equations with multiplicative noise are considered, to study the effects of fluctuations in domain growth. The equations are derived from a coarsegrained 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, 20041115)
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Open AccessWe 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; HernándezMachado, Aurora; Sancho, Jose Maria (American Physical Society, 19931001)
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Open AccessFront 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, 19970901)
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Open AccessA twodimensional reactiondiffusion 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, 19921001)
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Open AccessWe develop an algorithm to simulate a Gaussian stochastic process that is nonδcorrelated in both space and time coordinates. The colored noise obeys a linear reactiondiffusion 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, 19880601)
Article
Open AccessWe extend the partial resummation technique of FokkerPlanck 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 RiksWempner, BatozDhatt, PowellSimons y otros en el programa de elementos finitos F.E.A.P
Sancho, Jose Maria; Ortiz, Jesús (20090309T16:16:24Z)
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Open AccessLos 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, 20070228)
Article
Open AccessWe 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 equation approach for slow dynamics in magnetic systems
Sancho, Jose Maria; Lacasta Palacio, Ana María; Torrent Serra, Maria del Carmen; García Ojalvo, Jordi; Tejeda Gómez, José Arturo (Elsevier Science, 1993)
Article
Restricted access  publisher's policyWe present a magnetic model based on a Langevin equation which exhibits slow relaxation dynamics of ln(t) type. The system is composed of magnetic particles which are under the influence of a local potential and interact ... 
Langevin equations with multiplicative noise: application to domain growth
Sancho, Jose Maria; HernándezMachado, A.; Ramírez de la Piscina Millán, Laureano; Lacasta Palacio, Ana María (Jagiellonian University, Polish Academy of Arts and Sciences, 19930501)
Article
Open AccessLangevin Equations of GinzburgLandau form, with multiplicative noise, are proposed to study the effects of fluctuations in domain growth. These equations are derived from a coarsegrained methodology. The CahnHiliardCook ... 
Modelization of surface diffusion of a molecular dimer
Romero, A. H.; Lacasta Palacio, Ana María; Sancho, Jose Maria (American Physical Society, 20040520)
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Open AccessA 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 GinzburgLandau equations with multiplicative noise: application to domain growth
Ramírez de la Piscina Millán, Laureano; Sancho, Jose Maria; Hernández Machado, Aurora (The American Physical Society, 19930701)
Article
Open AccessWe 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 ...