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Seminars

The unexpected synchronization

Speaker Prof. Zoltán Néda
Affiliation Babeș-Bolyai University, Romania
Date August 17, 2012 (Fri)
Time 4:00 p.m.
Venue Room 522, 5/F, Chong Yuet Ming Physics Building, HKU

Abstract

Emerging synchronization of a large number of non-identical oscillators coupled through phase-minimizing forces is a fascinating collective behavior. Such phenomena are frequent in biological and social systems. Biological and social systems are usually more complex than simple mechanical or electric oscillators, and one might assume that synchronization is not their primary aim. A recently introduced synchronization model assumes that spontaneous synchronization might arise also as a byproduct of various optimization processes. Therefore, models that aim to describe realistically such systems should take also this possibility into consideration and step over the picture offered by simple physical oscillators interacting through phase-minimizing forces. The present talk contributes in such sense, considering a system of oscillators coupled through simple optimization rules. The oscillators are stochastic elements capable of emitting pulses and detecting the pulse emitted by the others. They have several operational modes, characterized by different oscillating periods. Shifting between these modes is induced by a simple optimization rule: the average output intensity of the oscillators is kept around a fixed G threshold. This dynamical rule has the role of coupling and triggers a complex collective behavior. Computer simulations suggest that for a given interval of the G parameter partial synchronization of the elements can occur. Appearance and disappearance of synchronization as a function of G indicates a phase-transition type behavior. The observed synchronization is highly nontrivial. In contrast with simple synchronization models, here no direct phase-difference minimizing interactions are considered. Another important aspect of the considered system is that the periodicity of the output for the whole ensemble is increased relative to the periodicity level of one element. This suggests interesting practical applications as well. An experimental realization of the system is also discussed.

Coffee and tea will be served 20 minutes prior to the seminar.