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Yves Pomeau
Yves Pomeau, born in 1942, is a French mathematician and physicist, emeritus research director at the CNRS and corresponding member of the French Academy of sciences. He was one of the founders of thLaboratoire de Physique Statistique, École Normale Supérieure, Paris He is the son of René Pomeau. Career Yves Pomeau did his state thesis in plasma physics, almost without any adviser, at the University of Orsay-France in 1970. After his thesis, he spent a year as a postdoc with Ilya Prigogine in Brussels. He was a researcher at the CNRS from 1965 to 2006, ending his career as DR0 in the Physics Department of the Ecole Normale Supérieure (ENS) (Statistical Physics Laboratory) in 2006. He was a lecturer in physics at the École Polytechnique for two years (1982–1984), then a scientific expert with the Direction générale de l'armement until January 2007. He was Professor, with tenure, part-time at the Department of Mathematics, University of Arizona, from 1990 to 2008. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lattice Gas Automaton
Lattice gas automata (LGCA), or lattice gas cellular automata, are a type of cellular automaton used to simulate fluid flows, pioneered by HPP model, Hardy–Pomeau–de Pazzis and Uriel Frisch, Frisch–Brosl Hasslacher, Hasslacher–Yves Pomeau, Pomeau. They were the precursor to the lattice Boltzmann methods. From lattice gas automata, it is possible to derive the macroscopic Navier–Stokes equations. Interest in lattice gas automaton methods levelled off in the early 1990s, as the interest in the lattice Boltzmann started to rise. However, an LGCA variant, termed BIO-LGCA, is still widely used to model collective migration in biology. Basic principles As a cellular automaton, these models comprise a lattice, where the sites on the lattice can take a certain number of different states. In lattice gas, the various states are particles with certain velocities. Evolution of the simulation is done in discrete time steps. After each time step, the state at a given site can be determ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Connecticut
Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York to the west, and Long Island Sound to the south. Its capital is Hartford and its most populous city is Bridgeport. Historically the state is part of New England as well as the tri-state area with New York and New Jersey. The state is named for the Connecticut River which approximately bisects the state. The word "Connecticut" is derived from various anglicized spellings of "Quinnetuket”, a Mohegan-Pequot word for "long tidal river". Connecticut's first European settlers were Dutchmen who established a small, short-lived settlement called House of Hope in Hartford at the confluence of the Park and Connecticut Rivers. Half of Connecticut was initially claimed by the Dutch colony New Netherland, which included much of the land between the Connecticut and Delaware Rivers, although the firs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boolean Network
A Boolean network consists of a discrete set of boolean variables each of which has a Boolean function (possibly different for each variable) assigned to it which takes inputs from a subset of those variables and output that determines the state of the variable it is assigned to. This set of functions in effect determines a topology (connectivity) on the set of variables, which then become nodes in a network. Usually, the dynamics of the system is taken as a discrete time series where the state of the entire network at time ''t''+1 is determined by evaluating each variable's function on the state of the network at time ''t''. This may be done synchronously or asynchronously. Boolean networks have been used in biology to model regulatory networks. Although Boolean networks are a crude simplification of genetic reality where genes are not simple binary switches, there are several cases where they correctly convey the correct pattern of expressed and suppressed genes. The seemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Front (physics)
In physics, a front can be understood as an interface between two different possible states (either stable or unstable) in a physical system. For example, a weather front is the interface between two different density masses of air, in combustion where the flame is the interface between burned and unburned material or in population dynamics where the front is the interface between populated and unpopulated places. Fronts can be static or mobile depending on the conditions of the system, and the causes of the motion can be the variation of a free energy, where the most energetically favorable state invades the less favorable one, according to Pomeau or shape induced motion due to non-variation dynamics in the system, according to Alvarez-Socorro, Clerc, González-Cortés and Wilson. From a mathematical point of view, fronts are solutions of spatially extended systems connecting two steady states, and from dynamical systems point of view, a front corresponds to a heteroclinic orbit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timeline Of Computational Physics
The following timeline starts with the invention of the modern computer in the late interwar period. 1930s * John Vincent Atanasoff and Clifford Berry create the first electronic non-programmable, digital computing device, the Atanasoff–Berry Computer, that lasted from 1937 to 1942. 1940s *Nuclear bomb and ballistics simulations at Los Alamos National Laboratory and Ballistic Research Laboratory (BRL), respectively. * Monte Carlo simulation (voted one of the top 10 algorithms of the 20th century by Jack Dongarra and Francis Sullivan in the 2000 issue of Computing in Science and Engineering) is invented at Los Alamos National Laboratory by John von Neumann, Stanislaw Ulam and Nicholas Metropolis. * First hydrodynamic simulations performed at Los Alamos National Laboratory. * Ulam and von Neumann introduce the notion of cellular automata. 1950s * ''Equations of State Calculations by Fast Computing Machines'' introduces the Metropolis–Hastings algorithm. Also, important ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lattice Boltzmann Methods
The lattice Boltzmann methods (LBM), originated from the lattice gas automata (LGA) method (Hardy- Pomeau-Pazzis and Frisch- Hasslacher- Pomeau models), is a class of computational fluid dynamics (CFD) methods for fluid simulation. Instead of solving the Navier–Stokes equations directly, a fluid density on a lattice is simulated with streaming and collision (relaxation) processes. The method is versatile as the model fluid can straightforwardly be made to mimic common fluid behaviour like vapour/liquid coexistence, and so fluid systems such as liquid droplets can be simulated. Also, fluids in complex environments such as porous media can be straightforwardly simulated, whereas with complex boundaries other CFD methods can be hard to work with. Algorithm Unlike CFD methods that solve the conservation equations of macroscopic properties (i.e., mass, momentum, and energy) numerically, LBM models the fluid consisting of fictive particles, and such particles perform consecutive propa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brosl Hasslacher
Brosl Hasslacher (May 13, 1941 – November 11, 2005) was a theoretical physicist. Brosl Hasslacher obtained a bachelor's in physics from Harvard University in 1962. He did his Ph.D. with D.Z. Freeman and Yang Chen-Ning, C.N. Yang at the State University of New York at Stony Brook. After having several postdoctoral and research positions at Institute for Advanced Study in Princeton, New Jersey, Caltech, ENS in Paris, and CERN, he settled for more than twenty years at the Theoretical Division of the Los Alamos National Laboratory. There he was involved in theoretical, experimental, and numerical work in theoretical physics, high-energy physics, nonlinear dynamics, fluid dynamics, nanotechnology, and robotics. In the 1970s, he worked on the extended hadron model, collaborating with A. Neveu. During the 1980s, Hasslacher pioneered with Uriel Frisch and Yves Pomeau the Lattice Gas Automata, ''lattice-gas'' method for discrete simulation of fluid flow. As part of the Los Alamos Nation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uriel Frisch
Uriel Frisch (born in Agen, in France, on December 10, 1940) is a French mathematical physicist known for his work on fluid dynamics and turbulence. Biography From 1959 to 1963 Frisch was a student at the École Normale Supérieure. Early in his graduate studies, he became interested in turbulence, under the mentorship of Robert Kraichnan, a former assistant to Albert Einstein. Frisch earned a Ph.D. in 1967 from the University of Paris, and since then he has worked at the French National Centre for Scientific Research (CNRS). He retired in 2006, and became a director of research emeritus at CNRS.Curriculum vitae retrieved 2012-03-05. Frisch's wife Hélène is also a physicist, and the grand daughter of mathematician Paul Lévy [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Chaotic Maps
In mathematics, a chaotic map is a map (namely, an evolution function) that exhibits some sort of chaotic behavior. Maps may be parameterized by a discrete-time or a continuous-time parameter. Discrete maps usually take the form of iterated functions. Chaotic maps often occur in the study of dynamical systems. Chaotic maps often generate fractals. Although a fractal may be constructed by an iterative procedure, some fractals are studied in and of themselves, as sets rather than in terms of the map that generates them. This is often because there are several different iterative procedures to generate the same fractal. List of chaotic maps List of fractals * Cantor set * de Rham curve * Gravity set, or Mitchell-Green gravity set * Julia set - derived from complex quadratic map * Koch snowflake - special case of de Rham curve * Lyapunov fractal * Mandelbrot set - derived from complex quadratic map * Menger sponge * Newton fractal * Nova fractal - derived from Newton fractal * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Pulsation
Stellar pulsations are caused by expansions and contractions in the outer layers as a star seeks to maintain equilibrium. These fluctuations in stellar radius cause corresponding changes in the luminosity of the star. Astronomers are able to deduce this mechanism by measuring the spectrum and observing the Doppler effect. Many intrinsic variable stars that pulsate with large amplitudes, such as the classical Cepheids, RR Lyrae stars and large-amplitude Delta Scuti stars show regular light curves. This regular behavior is in contrast with the variability of stars that lie parallel to and to the high-luminosity/low-temperature side of the classical variable stars in the Hertzsprung–Russell diagram. These giant stars are observed to undergo pulsations ranging from weak irregularity, when one can still define an average cycling time or period, (as in most RV Tauri and semiregular variables) to the near absence of repetitiveness in the irregular variables. The W Virginis variables ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logistic Map
The logistic map is a polynomial mapping (equivalently, recurrence relation) of degree 2, often referred to as an archetypal example of how complex, chaotic behaviour can arise from very simple non-linear dynamical equations. The map was popularized in a 1976 paper by the biologist Robert May, in part as a discrete-time demographic model analogous to the logistic equation written down by Pierre François Verhulst. Mathematically, the logistic map is written where is a number between zero and one, that represents the ratio of existing population to the maximum possible population. This nonlinear difference equation is intended to capture two effects: * ''reproduction'' where the population will increase at a rate proportional to the current population when the population size is small. * ''starvation'' (density-dependent mortality) where the growth rate will decrease at a rate proportional to the value obtained by taking the theoretical "carrying capacity" of the environment l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intermittency
In dynamical systems, intermittency is the irregular alternation of phases of apparently periodic and chaotic dynamics ( Pomeau–Manneville dynamics), or different forms of chaotic dynamics (crisis-induced intermittency). Pomeau and Manneville described three routes to intermittency where a nearly periodic system shows irregularly spaced bursts of chaos. These (type I, II and III) correspond to the approach to a saddle-node bifurcation, a subcritical Hopf bifurcation, or an inverse period-doubling bifurcation. In the apparently periodic phases the behaviour is only nearly periodic, slowly drifting away from an unstable periodic orbit. Eventually the system gets far enough away from the periodic orbit to be affected by chaotic dynamics in the rest of the state space, until it gets close to the orbit again and returns to the nearly periodic behaviour. Since the time spent near the periodic orbit depends sensitively on how closely the system entered its vicinity (in turn dete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
