1,122 research outputs found
Emergent global oscillations in heterogeneous excitable media: The example of pancreatic beta cells
Using the standard van der Pol-FitzHugh-Nagumo excitable medium model I
demonstrate a novel generic mechanism, diversity, that provokes the emergence
of global oscillations from individually quiescent elements in heterogeneous
excitable media. This mechanism may be operating in the mammalian pancreas,
where excitable beta cells, quiescent when isolated, are found to oscillate
when coupled despite the absence of a pacemaker region.Comment: See home page http://lec.ugr.es/~julya
Weighted networks are more synchronizable: how and why
Most real-world networks display not only a heterogeneous distribution of
degrees, but also a heterogeneous distribution of weights in the strengths of
the connections. Each of these heterogeneities alone has been shown to suppress
synchronization in random networks of dynamical systems. Here we review our
recent findings that complete synchronization is significantly enhanced and
becomes independent of both distributions when the distribution of weights is
suitably combined with the distribution of degrees. We also present new results
addressing the optimality of our findings and extending our analysis to phase
synchronization in networks of non-identical dynamical units.Comment: Proceedings of the CNET 2004 (29 August - 2 September 2004
Chimera states: Effects of different coupling topologies
Collective behavior among coupled dynamical units can emerge in various forms
as a result of different coupling topologies as well as different types of
coupling functions. Chimera states have recently received ample attention as a
fascinating manifestation of collective behavior, in particular describing a
symmetry breaking spatiotemporal pattern where synchronized and desynchronized
states coexist in a network of coupled oscillators. In this perspective, we
review the emergence of different chimera states, focusing on the effects of
different coupling topologies that describe the interaction network connecting
the oscillators. We cover chimera states that emerge in local, nonlocal and
global coupling topologies, as well as in modular, temporal and multilayer
networks. We also provide an outline of challenges and directions for future
research.Comment: 7 two-column pages, 4 figures; Perspective accepted for publication
in EP
On Optimal Synchronization of Diffusively Coupled Heterogeneous Van der Pol Oscillators
This paper proposes a novel method to achieve and preserve synchronization
for a set of connected heterogeneous Van der Pol oscillators. Unlike the
state-of-the-art synchronization methods, in which a large coupling gain is
applied to couple any pair of connected oscillators, the proposed method first
casts the whole synchronization process into two phases. The first one
considers the period from the beginning to the first instant of
synchronization, while the second phase covers the following time in which
synchronization must be preserved. It is shown that a large coupling gain is
adopted for the first phase, while the averaged coupling gain to preserve the
synchronization in the second phase can be reduced significantly by using an
offline optimized coupling law. Efficiency and performance of this method are
confirmed by a set of numerical tests with different graphs and system
dynamics.Comment: To be published in IFAC World Congress, 202
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