19 research outputs found
Parametric ordering of complex systems
Cellular automata (CA) dynamics are ordered in terms of two global
parameters, computable {\sl a priori} from the description of rules. While one
of them (activity) has been used before, the second one is new; it estimates
the average sensitivity of rules to small configurational changes. For two
well-known families of rules, the Wolfram complexity Classes cluster
satisfactorily. The observed simultaneous occurrence of sharp and smooth
transitions from ordered to disordered dynamics in CA can be explained with the
two-parameter diagram
Transport Phenomena at a Critical Point -- Thermal Conduction in the Creutz Cellular Automaton --
Nature of energy transport around a critical point is studied in the Creutz
cellular automaton. Fourier heat law is confirmed to hold in this model by a
direct measurement of heat flow under a temperature gradient. The thermal
conductivity is carefully investigated near the phase transition by the use of
the Kubo formula. As the result, the thermal conductivity is found to take a
finite value at the critical point contrary to some previous works. Equal-time
correlation of the heat flow is also analyzed by a mean-field type
approximation to investigate the temperature dependence of thermal
conductivity. A variant of the Creutz cellular automaton called the Q2R is also
investigated and similar results are obtained.Comment: 27 pages including 14figure