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Autor Brito, Ricardo |
Documentos disponibles escritos por este autor (47)
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It is shown that neither the Schrödinger equation nor the Klein-Gordon one with logarithmic nonlinearities have dissipative solutions. In the case of one-dimensional space, numerical experiments with different Cauchy data, in the nonrelativistic[...]texto impreso
It is shown that the Schrödinger equation nor the Klein-Gordon one with logarithmic nonlinearities have dissipative solutions. In the case of one-dimensional space, numerical experiments with different Cauchy data, in the nonrelativistic case, l[...]texto impreso
Brito, Ricardo ; Soto, R. | 2007-12In this paper we present a method to calculate Casimir Forces for non equilibrium systems with long range correlations. The origin of the force are the fluctuating fields, and the modification that the external, macroscopic objects induce in the[...]texto impreso
Brito, Ricardo ; Soto, R. | 2009-12It has been recently reported that a granular mixture in which grains differ in their restitution coefficients presents segregation: the more inelastic particles sink to the bottom. When other segregation mechanisms as buoyancy and the Brazil nu[...]texto impreso
An adiabatic piston, separating two granular gases prepared in the same macroscopic state, is found to eventually collapse to one of the sides. This new instability is explained by a simple macroscopic theory which is furthermore in qualitative [...]texto impreso
The solutions of the homogeneous nonlinear Boltzmann equation for inelastic Maxwell models, when driven by different types of thermostats, show, in general, overpopulated high energy tails of the form similar toexp(-ac), with power law tails and[...]texto impreso
Casimir forces can appear between intrusions placed in different media driven by several fluctuation mechanisms, either in equilibrium or out of it. Herein, we develop a general formalism to obtain such forces from the dynamical equations of the[...]texto impreso
The time dependence of deviations from the Gaussian state in a freely cooling homogeneous system of smooth inelastically colliding spheres is investigated by kinetic theory. We determine the full time dependence of the coefficients of an expansi[...]texto impreso
Rodríguez Parrondo, Juan Manuel ; Blanco, J. M. ; Cao García, Francisco Javier ; Brito, Ricardo | E D P Sciences | 1998-08-01The efficiency of different types of Brownian motors is calculated analytically and numerically. We find that motors based on flashing ratchets present a,low efficiency and an unavoidable entropy production. On the other hand, a certain class of[...]texto impreso
A collisional model of a confined quasi-two-dimensional granular mixture is considered to analyze homogeneous steady states. The model includes an effective mechanism to transfer the kinetic energy injected by vibration in the vertical direction[...]texto impreso
The total energy E(t) in a fluid of inelastic particles is dissipated through inelastic collisions. When such systems are prepared in a homogeneous initial state and evolve undriven, E(t) decays initially as t^(?2) ~ exp[?2?? ] (known as Haff's [...]texto impreso
A lattice gas automaton lacks Galilei invariance, and equilibria of systems moving with a finite speed \u --> \ are not simply related by a Galilei transformation to the equilibrium distribution in the rest frame. In the hydrodynamic description[...]texto impreso
In the present work, we propose a method to determine fluctuation-induced forces in nonequilibrium systems. These forces are the analog of the well-known Casimir forces, which were originally introduced in quantum field theory and later extended[...]texto impreso
We present a generalization of the Green-Kubo expressions for thermal transport coefficients mu in complex fluids of the generic form mu=mu(infinity)+integral(infinity)(0) dtV(-1) (0), i.e. a sum of an instantaneous transp[...]texto impreso
Muñoz Tapia, R. ; Brito, Ricardo ; Rodríguez Parrondo, Juan Manuel | American Physical Society | 2017-09-26Passive filters allowing the exchange of particles in a narrow band of energy are currently used in microrefrigerators and energy transducers. In this Rapid Communication, we analyze their thermal properties using linear irreversible thermodynam[...]texto impreso
Monte Carlo simulations of the spatially homogeneous Boltzmann equation for inelastic Maxwell molecules, performed by Baldassarri et al. (cond-mat/0111066), have shown that general classes of initial distributions evolve for large times into a s[...]texto impreso
Schnautz, T. ; Brito, Ricardo ; Kruelle, C.A. ; Rehberg, I. | American Physical Society | 2005-07-08Transport effects in a monolayer consisting of a binary granular mixture, confined in a horizontally vibrating circular dish, are studied experimentally and compared with a reduced theoretical model. Depending on the ratio of the particles' mate[...]texto impreso
Non-mean-field-type excess correlations at short times are present in three-dimensional (3D) computer simulations of the velocity autocorrelation function, but absent in 1D, 2D, and 4D. They are caused by ring collisions in a quasi-3D slab of si[...]texto impreso
The use of bibliometric indicators would simplify research assessments. The 2014 Research Excellence Framework (REF) is a peer review assessment of UK universities, whose results can be taken as benchmarks for bibliometric indicators. In this st[...]texto impreso
The inverse two-spin correlation function of a one-dimensional three-state Potts lattice with constant nearest-neighbor interactions in a uniform external field is derived exactly. It is shown that the external field induces long-range correlati[...]texto impreso
Brito, Ricardo ; Bussemaker, H. J. ; Ernst, M. H. ; Matsui, J. | 1995-09Using analytic and simulation techniques, we study the long-and intermediate-time behavior of the velocity autocorrelation function in two-dimensional lattice gas automata with stationary states that violate detailed balance. Such models are pro[...]texto impreso
Van Noije, T. P. C. ; Ernst, M. H. ; Brito, Ricardo ; García Orza, José Antonio | American Physical Society | 1997-07-21Using fluctuating hydrodynamics we describe the slow buildup of long range spatial correlations in a freely evolving fluid of inelastic hard spheres. In the incompressible limit, the behavior of spatial velocity correlations (including r^(-d) be[...]texto impreso
We present generalized Green-Kubo expressions for thermal transport coefficients mu in non-conservative fluid-type systems, of the generic form mu = mu(infinity)+ integral(o)(infinity) dtV(-1) [I-epsilon exp[tL] I](0), where exp[tL] is a pseudo-[...]texto impreso
Spatial fluctuations in dissipative systems, such as rapid granular flows, behave very differently from those in elastic fluids. Fluctuations in the flow field drive the linear and nonlinear instability in the density field (clustering), while v[...]texto impreso
García Orza, José Antonio ; Brito, Ricardo ; Van Noije, T. P. C. ; Ernst, M. H. | 1997-08An initially homogeneous freely evolving fluid of inelastic hard spheres develops inhomogeneities in the dow field u(r, t) (vortices) and in the density held n(r, t) (clusters), driven by unstable fluctuations, delta a = {delta n, delta u}. Thei[...]texto impreso
The majority of lattice gases have, apart from the physical conserved quantities of particle number, momentum and energy, spurious ones, usually staggered in space and time. At the level of linear excitations these staggered modes may be purely [...]texto impreso
Martínez, Froilán C. ; Cuesta, José A. ; Molera, Juan M. ; Brito, Ricardo | 1995-02Deterministic and stochastic cellular automata models available to study two-dimensional traffic fIow are compared in this paper. It is shown that a connection between them can be made only when the infinite time and infinite system limits are t[...]texto impreso
FCHC lattice gases are the basic models for studying flow problems in three-dimensional systems. This paper presents a self-contained theoretical analysis and some computer simulations of such lattice gases, extended to include an arbitrary numb[...]texto impreso
In the double rank analysis of research publications, the local rank position of a country or institution publication is expressed as a function of the world rank position. Excluding some highly or lowly cited publications, the double rank plot [...]texto impreso
The dynamics of inelastic hard spheres is described in terms of the binary collision expansion, yielding the corresponding pseudo-liouville equation and BBGKY hierarchy for the reduced distribution functions. Based on cluster expansion technique[...]texto impreso
The kinetic theory for tagged-particle problems in lattice-gas cellular automata is extended beyond Boltzmann's mean-field approximation by including correlated ring-type collisions. This theory provides explicit expressions for the velocity aut[...]texto impreso
This paper deals with solutions of the nonlinear Boltzmann equation for spatially uniform freely cooling inelastic Maxwell models for large times and for large velocities, and the nonuniform convergence to these limits. We demonstrate how the ve[...]texto impreso
We investigate the segregation of a dense binary mixture of granular particles that only differ in their restitution coefficient. The mixture is vertically vibrated in the presence of gravity. We find a partial segregation of the species, where [...]texto impreso
We review some exact results for the morion of a tagged particle in simple models. Then, we study the density dependence of the sill-diffusion coefficient D_(N)(?) in lattice systems with simple symmetric exclusion in which the particles can jum[...]texto impreso
The shear viscosity in the dilute regime of a model for confined granular matter is studied by simulations and kinetic theory. The model consists on projecting into two dimensions the motion of vibrofluidized granular matter in shallow boxes by [...]texto impreso
The shear viscosity in the dilute regime of a model for confined granular matter is studied by simulations and kinetic theory. The model consists on projecting into two dimensions the motion of vibrofluidized granular matter in shallow boxes by [...]texto impreso
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Van Noije, T. P. C. ; Ernst, M. H. ; Brito, Ricardo | 1998-05The clustering instability in freely evolving granular fluids manifests itself in the density-density correlation function and structure factor. These functions are calculated from fluctuating hydrodynamics. As time increases, the structure fact[...]texto impreso
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The majority of LGCAs has spurious conservation laws, the so-called staggered invariants, first discovered by Kadanoff, McNamara, and Zanetti. Consequently there are additional hydrodynamic modes of diffusive type, which modify mode coupling the[...]texto impreso
Grosfils, Patrick ; Boon, Jean-Pierre ; Brito, Ricardo ; Ernst, M. H. | American Physical Society | 1993-10We investigate the space and time behavior of spontaneous thermohydrodynamic fluctuations in a simple fluid modeled by a lattice-gas automaton and develop the statistical-mechanical theory of thermal lattice gases to compute the dynamical struct[...]texto impreso
The complete time dependence of the stress-stress correlation functions in lattice gas cellular automata is calculated from the ring kinetic theory using numerical and analytical methods. This provides corrections, typically of 10-20%, to the us[...]texto impreso
Objectives: Research is the foundation of technological progress; the aim of this study is to investigate research success in the USA, the EU and other countries in basic medical, biochemical and biotechnological topics. Methods: Research assess[...]texto impreso
Molera, Juan M. ; Martínez, Froilán C. ; Cuesta, José A. ; Brito, Ricardo | 1995-01In this paper we present a theoretical analysis of a recently proposed two-dimensional cellular automata model for traffic flow in cities with the ingredient of a turning capability. Numerical simulations of this model show that there is a trans[...]texto impreso
A kinetic description of lattice-gas automaton models for reaction-diffusion systems is presented. It provides corrections to the mean-field rate equations in the diffusion-limited regime. When applied to the two-species Maginu model, the theory[...]texto impreso
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In this paper we show how, under certain restrictions, the hydrodynamic equations for the freely evolving granular fluid fit within the framework of the time dependent Landau-Ginzburg (LG) models for critical and unstable fluids. The granular fl[...]