5,942 research outputs found
Recurrence-based time series analysis by means of complex network methods
Complex networks are an important paradigm of modern complex systems sciences
which allows quantitatively assessing the structural properties of systems
composed of different interacting entities. During the last years, intensive
efforts have been spent on applying network-based concepts also for the
analysis of dynamically relevant higher-order statistical properties of time
series. Notably, many corresponding approaches are closely related with the
concept of recurrence in phase space. In this paper, we review recent
methodological advances in time series analysis based on complex networks, with
a special emphasis on methods founded on recurrence plots. The potentials and
limitations of the individual methods are discussed and illustrated for
paradigmatic examples of dynamical systems as well as for real-world time
series. Complex network measures are shown to provide information about
structural features of dynamical systems that are complementary to those
characterized by other methods of time series analysis and, hence,
substantially enrich the knowledge gathered from other existing (linear as well
as nonlinear) approaches.Comment: To be published in International Journal of Bifurcation and Chaos
(2011
Second-Order Consensus of Networked Mechanical Systems With Communication Delays
In this paper, we consider the second-order consensus problem for networked
mechanical systems subjected to nonuniform communication delays, and the
mechanical systems are assumed to interact on a general directed topology. We
propose an adaptive controller plus a distributed velocity observer to realize
the objective of second-order consensus. It is shown that both the positions
and velocities of the mechanical agents synchronize, and furthermore, the
velocities of the mechanical agents converge to the scaled weighted average
value of their initial ones. We further demonstrate that the proposed
second-order consensus scheme can be used to solve the leader-follower
synchronization problem with a constant-velocity leader and under constant
communication delays. Simulation results are provided to illustrate the
performance of the proposed adaptive controllers.Comment: 16 pages, 5 figures, submitted to IEEE Transactions on Automatic
Contro
Concurrent enhancement of percolation and synchronization in adaptive networks
Co-evolutionary adaptive mechanisms are not only ubiquitous in nature, but
also beneficial for the functioning of a variety of systems. We here consider
an adaptive network of oscillators with a stochastic, fitness-based, rule of
connectivity, and show that it self-organizes from fragmented and incoherent
states to connected and synchronized ones. The synchronization and percolation
are associated to abrupt transitions, and they are concurrently (and
significantly) enhanced as compared to the non-adaptive case. Finally we
provide evidence that only partial adaptation is sufficient to determine these
enhancements. Our study, therefore, indicates that inclusion of simple adaptive
mechanisms can efficiently describe some emergent features of networked
systems' collective behaviors, and suggests also self-organized ways to control
synchronization and percolation in natural and social systems.Comment: Published in Scientific Report
- …