1,377 research outputs found
Transition from anticipatory to lag synchronization via complete synchronization in time-delay systems
The existence of anticipatory, complete and lag synchronization in a single
system having two different time-delays, that is feedback delay and
coupling delay , is identified. The transition from anticipatory to
complete synchronization and from complete to lag synchronization as a function
of coupling delay with suitable stability condition is discussed. The
existence of anticipatory and lag synchronization is characterized both by the
minimum of similarity function and the transition from on-off intermittency to
periodic structure in laminar phase distribution.Comment: 14 Pages and 12 Figure
Phase synchronization in time-delay systems
Though the notion of phase synchronization has been well studied in chaotic
dynamical systems without delay, it has not been realized yet in chaotic
time-delay systems exhibiting non-phase coherent hyperchaotic attractors. In
this article we report the first identification of phase synchronization in
coupled time-delay systems exhibiting hyperchaotic attractor. We show that
there is a transition from non-synchronized behavior to phase and then to
generalized synchronization as a function of coupling strength. These
transitions are characterized by recurrence quantification analysis, by phase
differences based on a new transformation of the attractors and also by the
changes in the Lyapunov exponents. We have found these transitions in coupled
piece-wise linear and in Mackey-Glass time-delay systems.Comment: 4 pages, 3 Figures (To appear in Physical Review E Rapid
Communication
Motion of Curves and Surfaces and Nonlinear Evolution Equations in (2+1) Dimensions
It is shown that a class of important integrable nonlinear evolution
equations in (2+1) dimensions can be associated with the motion of space curves
endowed with an extra spatial variable or equivalently, moving surfaces.
Geometrical invariants then define topological conserved quantities. Underlying
evolution equations are shown to be associated with a triad of linear
equations. Our examples include Ishimori equation and Myrzakulov equations
which are shown to be geometrically equivalent to Davey-Stewartson and Zakharov
-Strachan (2+1) dimensional nonlinear Schr\"odinger equations respectively.Comment: 13 pages, RevTeX, to appear in J. Math. Phy
Wheat Growth, Yield, and Yield Contributing Attributes as a Function of Nitrogen Levels
To evaluate the effect of different levels of nitrogen on growth and yield of wheat a field experiment was conducted in 2017-18 at research area of cereals and pulses section, Ayyub agricultural research institute, Faisalabad. Eight levels of nitrogen i.e. 0, 29, 58, 87, 116, 145, 174, 203 kg ha-1 were evaluated. Experiment was laid out under randomized complete block design (RCBD) with three replications with a net plot size of 10×5m. Data were recorded for growth and yield parameters like number of tillers, plant height, spiklets per spike, seeds per spike, biological yield, 1000 grain weight, grain yield and harvest index. Different levels of nitrogen significantly increased all the growth and yield parameters. Maximum number of tillers, highest plant height and biological yield was recorded from the treatment where nitrogen was applied @ 203 Kg ha-1 while 1000 grain yield, seeds per spike and grain yield was achieved highest from where nitrogen applied @ 145 Kg ha-1
Experimental confirmation of chaotic phase synchronization in coupled time-delayed electronic circuits
We report the first experimental demonstration of chaotic phase
synchronization (CPS) in unidirectionally coupled time-delay systems using
electronic circuits. We have also implemented experimentally an efficient
methodology for characterizing CPS, namely the localized sets. Snapshots of the
evolution of coupled systems and the sets as observed from the oscilloscope
confirming CPS are shown experimentally. Numerical results from different
approaches, namely phase differences, localized sets, changes in the largest
Lyapunov exponents and the correlation of probability of recurrence
(), corroborate the experimental observations.Comment: Physical_Review_E_82_065201(R) 201
Transition from phase to generalized synchronization in time-delay systems
The notion of phase synchronization in time-delay systems, exhibiting highly
non-phase-coherent attractors, has not been realized yet even though it has
been well studied in chaotic dynamical systems without delay. We report the
identification of phase synchronization in coupled nonidentical piece-wise
linear and in coupled Mackey-Glass time-delay systems with highly
non-phase-coherent regimes. We show that there is a transition from
non-synchronized behavior to phase and then to generalized synchronization as a
function of coupling strength. We have introduced a transformation to capture
the phase of the non-phase coherent attractors, which works equally well for
both the time-delay systems. The instantaneous phases of the above coupled
systems calculated from the transformed attractors satisfy both the phase and
mean frequency locking conditions. These transitions are also characterized in
terms of recurrence based indices, namely generalized autocorrelation function
, correlation of probability of recurrence (CPR), joint probability of
recurrence (JPR) and similarity of probability of recurrence (SPR). We have
quantified the different synchronization regimes in terms of these indices. The
existence of phase synchronization is also characterized by typical transitions
in the Lyapunov exponents of the coupled time-delay systems.Comment: Accepted for publication in CHAO
Quantitative Precipitation Nowcasting: A Lagrangian Pixel-Based Approach
Short-term high-resolution precipitation forecasting has important implications for navigation, flood forecasting, and other hydrological and meteorological concerns. This article introduces a pixel-based algorithm for Short-term Quantitative Precipitation Forecasting (SQPF) using radar-based rainfall data. The proposed algorithm called Pixel- Based Nowcasting (PBN) tracks severe storms with a hierarchical mesh-tracking algorithm to capture storm advection in space and time at high resolution from radar imagers. The extracted advection field is then extended to nowcast the rainfall field in the next 3. hr based on a pixel-based Lagrangian dynamic model. The proposed algorithm is compared with two other nowcasting algorithms (WCN: Watershed-Clustering Nowcasting and PER: PERsistency) for ten thunderstorm events over the conterminous United States. Object-based verification metric and traditional statistics have been used to evaluate the performance of the proposed algorithm. It is shown that the proposed algorithm is superior over comparison algorithms and is effective in tracking and predicting severe storm events for the next few hours. © 2012 Elsevier B.V
Global phase synchronization in an array of time-delay systems
We report the identification of global phase synchronization (GPS) in a
linear array of unidirectionally coupled Mackey-Glass time-delay systems
exhibiting highly non-phase-coherent chaotic attractors with complex
topological structure. In particular, we show that the dynamical organization
of all the coupled time-delay systems in the array to form GPS is achieved by
sequential synchronization as a function of the coupling strength. Further, the
asynchronous ones in the array with respect to the main sequentially
synchronized cluster organize themselves to form clusters before they achieve
synchronization with the main cluster. We have confirmed these results by
estimating instantaneous phases including phase difference, average phase,
average frequency, frequency ratio and their differences from suitably
transformed phase coherent attractors after using a nonlinear transformation of
the original non-phase-coherent attractors. The results are further
corroborated using two other independent approaches based on recurrence
analysis and the concept of localized sets from the original non-phase-coherent
attractors directly without explicitly introducing the measure of phase.Comment: 11 pages, 13 figures, Appear in Physical Review
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