270,090 research outputs found
Parameter mismatches,variable delay times and synchronization in time-delayed systems
We investigate synchronization between two unidirectionally linearly coupled
chaotic non-identical time-delayed systems and show that parameter mismatches
are of crucial importance to achieve synchronization. We establish that
independent of the relation between the delay time in the coupled systems and
the coupling delay time, only retarded synchronization with the coupling delay
time is obtained. We show that with parameter mismatch or without it neither
complete nor anticipating synchronization occurs. We derive existence and
stability conditions for the retarded synchronization manifold. We demonstrate
our approach using examples of the Ikeda and Mackey-Glass models. Also for the
first time we investigate chaos synchronization in time-delayed systems with
variable delay time and find both existence and sufficient stability conditions
for the retarded synchronization manifold with the coupling delay lag time.
Also for the first time we consider synchronization between two
unidirectionally coupled chaotic multi-feedback Ikeda systems and derive
existence and stability conditions for the different anticipating, lag, and
complete synchronization regimes.Comment: 12 page
Synchronization of chaotic oscillator time scales
This paper deals with the chaotic oscillator synchronization. A new approach
to detect the synchronized behaviour of chaotic oscillators has been proposed.
This approach is based on the analysis of different time scales in the time
series generated by the coupled chaotic oscillators. It has been shown that
complete synchronization, phase synchronization, lag synchronization and
generalized synchronization are the particular cases of the synchronized
behavior called as "time--scale synchronization". The quantitative measure of
chaotic oscillator synchronous behavior has been proposed. This approach has
been applied for the coupled Rossler systems.Comment: 29 pages, 11 figures, published in JETP. 100, 4 (2005) 784-79
Feedback-dependent control of stochastic synchronization in coupled neural systems
We investigate the synchronization dynamics of two coupled noise-driven
FitzHugh-Nagumo systems, representing two neural populations. For certain
choices of the noise intensities and coupling strength, we find cooperative
stochastic dynamics such as frequency synchronization and phase
synchronization, where the degree of synchronization can be quantified by the
ratio of the interspike interval of the two excitable neural populations and
the phase synchronization index, respectively. The stochastic synchronization
can be either enhanced or suppressed by local time-delayed feedback control,
depending upon the delay time and the coupling strength. The control depends
crucially upon the coupling scheme of the control force, i.e., whether the
control force is generated from the activator or inhibitor signal, and applied
to either component. For inhibitor self-coupling, synchronization is most
strongly enhanced, whereas for activator self-coupling there exist distinct
values of the delay time where the synchronization is strongly suppressed even
in the strong synchronization regime. For cross-coupling strongly modulated
behavior is found
Synchronization service integrated into routing layer in wireless sensor networks
The time synchronization problem needs to be considered in a distributed system. In Wireless Sensor Networks (WSNs) this issue must be solved with limited computational, communication and energy resources. Many synchronization protocols exist for WSNs. However, in most cases these protocols are independent entities with specific packets, communication scheme and network hierarchy. This solution is not energy efficient. Because it is very rare for synchronization not to be necessary in WSNs, we advocate integrating the synchronization service into the routing layer. We have implemented this approach in a new synchronization protocol called Routing Integrated Synchronization Service (RISS). Our tests show that RISS is very time and energy efficient and also is characterized by a small overhead. We have compared its performance experimentally to that of the FTSP synchronization protocol and it has proved to offer better time precision than the latter protocol
Phase Synchronization in Temperature and Precipitation Records
We study phase synchronization between atmospheric variables such as daily
mean temperature and daily precipitation records. We find significant phase
synchronization between records of Oxford and Vienna as well as between the
records of precipitation and temperature in each city. To find the time delay
in the synchronization between the records we study the time lag phase
synchronization when the records are shifted by a variable time interval of
days. We also compare the results of the method with the classical
cross-correlation method and find that in certain cases the phase
synchronization yields more significant results.Comment: 11 pages including 8 figure
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