7,868 research outputs found
Time lagged ordinal partition networks for capturing dynamics of continuous dynamical systems
We investigate a generalised version of the recently proposed ordinal
partition time series to network transformation algorithm. Firstly we introduce
a fixed time lag for the elements of each partition that is selected using
techniques from traditional time delay embedding. The resulting partitions
define regions in the embedding phase space that are mapped to nodes in the
network space. Edges are allocated between nodes based on temporal succession
thus creating a Markov chain representation of the time series. We then apply
this new transformation algorithm to time series generated by the R\"ossler
system and find that periodic dynamics translate to ring structures whereas
chaotic time series translate to band or tube-like structures -- thereby
indicating that our algorithm generates networks whose structure is sensitive
to system dynamics. Furthermore we demonstrate that simple network measures
including the mean out degree and variance of out degrees can track changes in
the dynamical behaviour in a manner comparable to the largest Lyapunov
exponent. We also apply the same analysis to experimental time series generated
by a diode resonator circuit and show that the network size, mean shortest path
length and network diameter are highly sensitive to the interior crisis
captured in this particular data set
Homoclinic orbits, and self-excited and hidden attractors in a Lorenz-like system describing convective fluid motion
In this tutorial, we discuss self-excited and hidden attractors for systems
of differential equations. We considered the example of a Lorenz-like system
derived from the well-known Glukhovsky--Dolghansky and Rabinovich systems, to
demonstrate the analysis of self-excited and hidden attractors and their
characteristics. We applied the fishing principle to demonstrate the existence
of a homoclinic orbit, proved the dissipativity and completeness of the system,
and found absorbing and positively invariant sets. We have shown that this
system has a self-excited attractor and a hidden attractor for certain
parameters. The upper estimates of the Lyapunov dimension of self-excited and
hidden attractors were obtained analytically.Comment: submitted to EP
Dynamical Systems, Stability, and Chaos
In this expository and resources chapter we review selected aspects of the
mathematics of dynamical systems, stability, and chaos, within a historical
framework that draws together two threads of its early development: celestial
mechanics and control theory, and focussing on qualitative theory. From this
perspective we show how concepts of stability enable us to classify dynamical
equations and their solutions and connect the key issues of nonlinearity,
bifurcation, control, and uncertainty that are common to time-dependent
problems in natural and engineered systems. We discuss stability and
bifurcations in three simple model problems, and conclude with a survey of
recent extensions of stability theory to complex networks.Comment: 28 pages, 10 figures. 26/04/2007: The book title was changed at the
last minute. No other changes have been made. Chapter 1 in: J.P. Denier and
J.S. Frederiksen (editors), Frontiers in Turbulence and Coherent Structures.
World Scientific Singapore 2007 (in press
Chaos in generically coupled phase oscillator networks with nonpairwise interactions
The Kuramoto-Sakaguchi system of coupled phase oscillators, where interaction
between oscillators is determined by a single harmonic of phase differences of
pairs of oscillators, has very simple emergent dynamics in the case of
identical oscillators that are globally coupled: there is a variational
structure that means the only attractors are full synchrony (in-phase) or splay
phase (rotating wave/full asynchrony) oscillations and the bifurcation between
these states is highly degenerate. Here we show that nonpairwise coupling -
including three and four-way interactions of the oscillator phases - that
appears generically at the next order in normal-form based calculations, can
give rise to complex emergent dynamics in symmetric phase oscillator networks.
In particular, we show that chaos can appear in the smallest possible dimension
of four coupled phase oscillators for a range of parameter values
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