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Spatiotemporal intermittency and scaling laws in coupled map lattices  [PDF]
Neelima Gupte,Zahera Jabeen
Physics , 2005,
Abstract: We discuss the spatiotemporal intermittency (STI) seen in coupled map lattices (CML-s). We identify the types of intermittency seen in such systems in the context of several specific CML-s. The Chat\'e-Manneville CML is introduced and the on-going debate on the connection of the spatiotemporal intermittency seen in this model with the problem of directed percolation is summarised. We also discuss the STI seen in the sine circle map model and its connection with the directed percolation problem, as well as the inhomogenous logistic map lattice which shows the novel phenomenon of spatial intermittency and other types of behaviour not seen in the other models. The connection of the bifurcation behaviour in this model with STI is touched upon. We conclude with a discussion of open problems.
Persistence at the onset of spatiotemporal intermittency in coupled map lattices  [PDF]
Gautam I. Menon,Sudeshna Sinha,Purusattam Ray
Physics , 2002, DOI: 10.1209/epl/i2003-00240-x
Abstract: We study persistence in coupled circle map lattices at the onset of spatiotemporal intermittency, an onset which marks a continuous transition, in the universality class of directed percolation, to a unique absorbing state. We obtain a local persistence exponent of theta_l = 1.49 +- 0.02 at this transition, a value which closely matches values for theta_l obtained in stochastic models of directed percolation. This result constitutes suggestive evidence for the universality of persistence exponents at the directed percolation transition. Given that many experimental systems are modelled accurately by coupled map lattices, experimental measurements of this persistence exponent may be feasible.
Intermittency in Inhomogeneous Coupled Map Lattices  [PDF]
Ashutosh Sharma,Neelima Gupte
Physics , 1999,
Abstract: We study the phenomenon of intermittency in inhomogeneous lattices of coupled map where inhomogeneity appears in the form of different values of map parameters at adjacent sites.The system exhibits spatiotemporal intermittency in various regions of parameter space.We identify the types of co-dimension two bifurcations which give rise to spatio-temporal or purely spatial intermittency and study the mechanism in one case, that of synchronised fixed point Power law distributions of laminar lengths is observed in vicinity of such co-dim 2 points and the exponents fall in three ranges for three different types of bifurcations. Three of the exponents seen in this model show good agreement with those observed in fluid experiments with quasi-one dimensional geometries.
Probabilistic signatures of spatiotemporal intermittency in the coupled sine circle map lattice  [PDF]
Zahera Jabeen,Neelima Gupte
Physics , 2008, DOI: 10.1007/s12043-008-0110-4
Abstract: The phase diagram of the coupled sine circle map lattice exhibits a variety of interesting phenomena including spreading regions with spatiotemporal intermittency, non-spreading regions with spatial intermittency, and coherent structures termed solitons. A cellular automaton mapping of the coupled map lattice maps the spreading to non-spreading transition to a transition from a probabilistic to a deterministic cellular automaton. The solitonic sector of the map shows spatiotemporal intermittency with soliton creation, propagation and annihilation. A probabilistic cellular automaton mapping is set up for this sector which can identify each one of these phenomena.
Spatiotemporal structure of Lyapunov vectors in chaotic coupled-map lattices  [PDF]
Ivan G. Szendro,Diego Pazó,Miguel A. Rodríguez,Juan M. López
Physics , 2007, DOI: 10.1103/PhysRevE.76.025202
Abstract: The spatiotemporal dynamics of Lyapunov vectors (LVs) in spatially extended chaotic systems is studied by means of coupled-map lattices. We determine intrinsic length scales and spatiotemporal correlations of LVs corresponding to the leading unstable directions by translating the problem to the language of scale-invariant growing surfaces. We find that the so-called 'characteristic' LVs exhibit spatial localization, strong clustering around given spatiotemporal loci, and remarkable dynamic scaling properties of the corresponding surfaces. In contrast, the commonly used backward LVs (obtained through Gram-Schmidt orthogonalization) spread all over the system and do not exhibit dynamic scaling due to artifacts in the dynamical correlations by construction.

Luo Xiao-shu,Fang Jin-qing,

中国物理 B , 2000,
Abstract: We propose a method that allows one to control spatiotemporal chaos by applying pulses proportional to the system variables and compressing the phase space of strange attractor in nonlinear system. The method is illustrated by the coupled map lattices at different strengths of coupling. Various numerical results are given. The advantage of this method is that it does not need to know any previous knowledge of the system dynamics.
Nonlinear feedback control of spatiotemporal chaos in coupled map lattices  [cached]
Jin-Qing Fang,M. K. Ali
Discrete Dynamics in Nature and Society , 1996, DOI: 10.1155/s1026022697000289
Abstract: We describe a nonlinear feedback functional method for study both of control and synchronization of spatiotemporal chaos. The method is illustrated by the coupled map lattices with five different connection forms. A key issue addressed is to find nonlinear feedback functions. Two large types of nonlinear feedback functions are introduced. The efficient and robustness of the method based on the flexibility of choices of nonlinear feedback functions are discussed. Various numerical results of nonlinear control are given. We have not found any difficulty for study both of control and synchronization using nonlinear feedback functional method. The method can also be extended to time continuous dynamical systems as well as to society problems.
Spatiotemporal intermittency and scaling laws in the coupled sine circle map lattice  [PDF]
Zahera Jabeen,Neelima Gupte
Physics , 2006, DOI: 10.1103/PhysRevE.74.016210
Abstract: We study spatio-temporal intermittency (STI) in a system of coupled sine circle maps. The phase diagram of the system shows parameter regimes with STI of both the directed percolation (DP) and non-DP class. STI with synchronized laminar behaviour belongs to the DP class. The regimes of non-DP behaviour show spatial intermittency (SI), where the temporal behaviour of both the laminar and burst regions is regular, and the distribution of laminar lengths scales as a power law. The regular temporal behaviour for the bursts seen in these regimes of spatial intermittency can be periodic or quasi-periodic, but the laminar length distributions scale with the same power-law, which is distinct from the DP case. STI with traveling wave (TW) laminar states also appears in the phase diagram. Soliton-like structures appear in this regime. These are responsible for cross-overs with accompanying non-universal exponents. The soliton lifetime distributions show power law scaling in regimes of long average soliton life-times, but peak at characteristic scales with a power-law tail in regimes of short average soliton life-times. The signatures of each type of intermittent behaviour can be found in the dynamical characterisers of the system viz. the eigenvalues of the stability matrix. We discuss the implications of our results for behaviour seen in other systems which exhibit spatio-temporal intermittency.
Effect of asynchronicity on the universal behaviour of coupled map lattices  [PDF]
Neelima Gupte,T. M. Janaki,Sudeshna Sinha
Physics , 2002,
Abstract: We investigate the spatiotemporal dynamics of coupled circle map lattices, evolving under synchronous (parallel) updating on one hand and asynchronous (random) updating rules on the other. Synchronous evolution of extended spatiotemporal systems, such as coupled circle map lattices, commonly yields multiple co-existing attractors, giving rise to phenomena strongly dependent on the initial lattice. By marked contrast numerical evidence here strongly indicates that asynchronous evolution eliminates most of the attractor states arising from special sets of initial conditions in synchronous systems, and tends to yield more global attractors. Thus the phenomenology arising from asynchronous evolution is more generic and robust in that it is obtained from many different classes of initial states. Further we show that in parameter regions where both asynchronous and synchronous evolution yield spatio-temporal intermittency, asynchronicity leads to better scaling behaviour.
A Spatiotemporal Chaotic Sequence Based on Coupled Chaotic Tent Map Lattices System With Uniform Distribution  [cached]
Jiandong Liu,Kai Yang
Journal of Computers , 2011, DOI: 10.4304/jcp.6.2.190-199
Abstract: A coupled chaotic map lattices system with uniform distribution (CML-UD) consisting of tent maps, which generates spatiotemporal chaos, is presented based on the security from the point view of cryptography. The system inherited the coupled diffusion and parallel iteration mechanism of coupled map lattices(CML). Through the dual non-linear effect of the rolled-out and folded-over of local lattices tent map and modular algorithms, CML-UD allows the system to enter into an ergodic state, and to rapidly generate uniform distributed multi-dimensional pseudo-random sequences concurrently. The experimental results show that, the spatiotemporal chaos sequences generated by the system has the same differential distribution character with the real random sequence of which each element has equal appearance rate, and it effectively restrains the short-period phenomenon which is easy to occur in digital chaotic system. In addition, it had many special properties such as zero correlation in total field, uniform invariable distribution and the maximum Lyapunov exponent is much bigger and steady. All of the properties suggest that the CML-UD possesses the potential application in encryption.
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