Friday, November 18, 2016

How synchrony and asynchrony co-exist

From the news article:
The team built a system of three coupled platforms, each supporting up to 15 ticking metronomes whose motions were individually tracked. A chimera state in this system consisted of in-phase, or synchronous, motion of a subset of the metronomes, and asynchronous motion of the others. By varying characteristics of the system, such as the strength of coupling between the platforms or the number of metronomes, they could deduce which factors led to more perfect chimera states. [...]

In addition to developing a method for better understanding these important, complex systems, Sorrentino views the effort to be a powerful educational tool. The tabletop scale and visual nature of the measurements and effects offer students more direct involvement with the concepts being investigated.

"It's a full experience for the student [and] we have a broad authorship," Sorrentino said, highlighting the collaboration between undergraduates, graduate students and senior researchers. "It's really a team effort."
This is the technical article described in the news article:

Symmetry effects on naturally arising chimera states in mechanical oscillator networks
Karen Blaha1, Ryan J. Burrus1, Jorge L. Orozco-Mora, Elvia Ruiz-Beltrán, Abu B. Siddique, V. D. Hatamipour and Francesco Sorrentino

Chaos 26, 116307 (2016);


Coupled oscillators were believed to exclusively exist in a state of synchrony or disorder until Kuramoto theoretically proved that the two states could coexist, called a chimera state, when portions of the population had a spatial dependent coupling. Recent work has demonstrated the spontaneous emergence of chimera states in an experiment involving mechanical oscillators coupled through a two platform swing. We constructed an experimental apparatus with three platforms that each contains a population of mechanical oscillators in order investigate the effects of a network symmetry on naturally arising chimera states. We considered in more detail the case of 15 metronomes per platform and observed that chimera states emerged as a broad range of parameters, namely, the metronomes' nominal frequency and the coupling strength between the platforms. A scalability study shows that chimera states no longer arise when the population size is reduced to three metronomes per platform. Furthermore, many chimera states are seen in the system when the coupling between platforms is asymmetric.

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