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Sep 22, 2013
09/13

by
Sudeshna Sinha

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We investigate the spatiotemporal dynamics of a network of coupled chaotic maps, with varying degrees of randomness in coupling connections. While strictly nearest neighbour coupling never allows spatiotemporal synchronization in our system, randomly rewiring some of those connections stabilises entire networks at $x^*$, where $x^*$ is the strongly unstable fixed point solution of the local chaotic map. In fact, the smallest degree of randomness in spatial connections opens up a window of...

Source: http://arxiv.org/abs/nlin/0205008v1

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Sep 23, 2013
09/13

by
Sitabhra Sinha; Sudeshna Sinha

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We study the evolution of a random weighted network with complex nonlinear dynamics at each node, whose activity may cease as a result of interactions with other nodes. Starting from a knowledge of the micro-level behaviour at each node, we develop a macroscopic description of the system in terms of the statistical features of the subnetwork of active nodes. We find the asymptotic characteristics of this subnetwork to be remarkably robust: the size of the active set is independent of the total...

Source: http://arxiv.org/abs/cond-mat/0510603v1

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Sep 23, 2013
09/13

by
Ramaswamy Jaganathan; Sudeshna Sinha

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A scheme of q-deformation of nonlinear maps is introduced. As a specific example, a q-deformation procedure related to the Tsallis q-exponential function is applied to the logistic map. Compared to the canonical logistic map, the resulting family of q-logistic maps is shown to have a wider spectrum of interesting behaviours, including the co-existence of attractors -- a phenomenon rare in one dimensional maps.

Source: http://arxiv.org/abs/nlin/0408034v1

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74

Sep 21, 2013
09/13

by
Sitabhra Sinha; Sudeshna Sinha

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We consider a random network of nonlinear maps exhibiting a wide range of local dynamics, with the links having normally distributed interaction strengths. The stability of such a system is examined in terms of the asymptotic fraction of nodes that persist in a non-zero state. Scaling results show that the probability of survival in the steady state agrees remarkably well with the May-Wigner stability criterion derived from linear stability arguments. This suggests universality of the...

Source: http://arxiv.org/abs/nlin/0402002v2

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Jul 20, 2013
07/13

by
Zahera Jabeen; Sudeshna Sinha

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We investigate the spatiotemporal dynamics of a network of coupled nonlinear oscillators, modeled by sine circle maps, with varying degrees of randomness in coupling connections. We show that the change in the basin of attraction of the spatiotemporal fixed point due to varying fraction of random links $p$, is crucially related to the nature of the local dynamics. Even the qualitative dependence of spatiotemporal regularity on $p$ changes drastically as the angular frequency of the oscillators...

Source: http://arxiv.org/abs/0804.0469v1

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Sep 23, 2013
09/13

by
Debabrata Biswas; Sudeshna Sinha

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The zeroes of the Husimi function provide a minimal description of individual quantum eigenstates and their distribution is of considerable interest. We provide here a numerical study for pseudo- integrable billiards which suggests that the zeroes tend to diffuse over phase space in a manner reminiscent of chaotic systems but nevertheless contain a subtle signature of pseudo-integrability. We also find that the zeroes depend sensitively on the position and momentum uncertainties with the...

Source: http://arxiv.org/abs/chao-dyn/9904047v1

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2.0

Jun 28, 2018
06/18

by
Anshul Choudhary; Sudeshna Sinha

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We consider a multi-species community modelled as a complex network of populations, where the links are given by a random asymmetric matrix J, with fraction 1-C of zero entries, where C reflects the over-all connectivity of the system. The non-zero elements of J are drawn from a gaussian distribution with mean 'mu' and standard deviation . The signs of the elements J reflect the nature of density-dependent interactions, such as predatory-prey, mutualism or competition, and their magnitudes...

Topics: Populations and Evolution, Biological Physics, Physics and Society, Quantitative Biology, Physics

Source: http://arxiv.org/abs/1509.08924

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2.0

Jun 29, 2018
06/18

by
Sudhanshu Shekhar Chaurasia; Sudeshna Sinha

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We explore the behaviour of an ensemble of chaotic oscillators coupled only to an external chaotic system, whose intrinsic dynamics may be similar or dissimilar to the group. Counter-intuitively, we find that a dissimilar external system manages to suppress the intrinsic chaos of the oscillators to fixed point dynamics, at sufficiently high coupling strengths. So, while synchronization is induced readily by coupling to an identical external system, control to fixed states is achieved only if...

Topics: Chaotic Dynamics, Nonlinear Sciences

Source: http://arxiv.org/abs/1607.00462

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Sep 19, 2013
09/13

by
Prashant M. Gade; Sudeshna Sinha

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We study the transition to phase synchronization in a model for the spread of infection defined on a small world network. It was shown (Phys. Rev. Lett. {\bf 86} (2001) 2909) that the transition occurs at a finite degree of disorder $p$, unlike equilibrium models where systems behave as random networks even at infinitesimal $p$ in the infinite size limit. We examine this system under variation of a parameter determining the driving rate, and show that the transition point decreases as we drive...

Source: http://arxiv.org/abs/cond-mat/0507164v1

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Sep 20, 2013
09/13

by
Prashant M. Gade; Sudeshna Sinha

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We study the dynamical behaviour of the collective field of chaotic systems on small world lattices. Coupled neuronal systems as well as coupled logistic maps are investigated. We observe that significant changes in dynamical properties occur only at a reasonably high strength of nonlocal coupling. Further, spectral features, such as signal-to-noise ratio (SNR), change monotonically with respect to the fraction of random rewiring, i.e. there is no optimal value of the rewiring fraction for...

Source: http://arxiv.org/abs/nlin/0405049v1

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7.0

Jun 28, 2018
06/18

by
Chandrakala Meena; K. Murali; Sudeshna Sinha

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We consider star networks of chaotic oscillators, with all end-nodes connected only to the central hub node, under diffusive coupling, conjugate coupling and mean-field type coupling. We observe the existence of chimeras in the end-nodes, which are identical in terms of the coupling environment and dynamical equations. Namely, the symmetry of the end-nodes is broken and co-existing groups with different synchronization features and attractor geometries emerge. Surprisingly, such chimera states...

Topics: Chaotic Dynamics, Nonlinear Sciences

Source: http://arxiv.org/abs/1509.01093

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4.0

Jun 30, 2018
06/18

by
Ankit Kumar; Vidit Agrawal; Sudeshna Sinha

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In this work we investigate time varying networks with complex dynamics at the nodes. We consider two scenarios of network change in an interval of time: first, we have the case where each link can change with probability pt, i.e. the network changes occur locally and independently at each node. Secondly we consider the case where the entire connectivity matrix changes with probability pt, i.e. the change is global. We show that network changes, occurring both locally and globally, yield an...

Topics: Nonlinear Sciences, Adaptation and Self-Organizing Systems

Source: http://arxiv.org/abs/1404.3196

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3.0

Jun 29, 2018
06/18

by
Vidit Agrawal; Promit Moitra; Sudeshna Sinha

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We explore the emergence of persistent infection in a patch of population, where the disease progression of the individuals is given by the SIRS model and an individual becomes infected on contact with another infected individual. We investigate the persistence of contagion qualitatively and quantitatively, under varying degrees of heterogeneity in the initial population. We observe that when the initial population is uniform, consisting of individuals at the same stage of disease progression,...

Topics: Quantitative Biology, Cellular Automata and Lattice Gases, Nonlinear Sciences, Populations and...

Source: http://arxiv.org/abs/1605.08575

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Sep 19, 2013
09/13

by
Ramakrishna Ramaswamy; Sudeshna Sinha; Neelima Gupte

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We describe adaptive control algorithms whereby a chaotic dynamical system can be steered to a target state with desired characteristics. A specific implementation considered has the objective of directing the system to a state which is more chaotic or mixed than the uncontrolled one. This methodology is easy to implement in discrete or continuous dynamical systems. It is robust and efficient, and has the additional advantage that knowledge of the detailed behaviour of the system is not...

Source: http://arxiv.org/abs/chao-dyn/9801024v1

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Jul 24, 2013
07/13

by
Swarup Poria; Manish Dev Shrimali; Sudeshna Sinha

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We investigate the spatiotemporal dynamics of a lattice of coupled chaotic maps whose coupling connections are dynamically rewired to random sites with probability p, namely at any instance of time, with probability p a regular link is switched to a random one. In a range of weak coupling, where spatiotemporal chaos exists for regular lattices (i.e. for p = 0), we find that p > 0 yields synchronized periodic orbits. Further we observe that this regularity occurs over a window of p values,...

Source: http://arxiv.org/abs/0807.0840v1

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Sep 18, 2013
09/13

by
T. M. Janaki; Sudeshna Sinha; Neelima Gupte

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We consider a lattice of coupled circle maps, a model arising naturally in descriptions of solid state phenomena such as Josephson junction arrays. We find that the onset of spatiotemporal intermittency (STI) in this system is analogous to directed percolation (DP), with the transition being to an unique absorbing state for low nonlinearities, and to weakly chaotic absorbing states for high nonlinearities. We find that the complete set of static exponents and spreading exponents at all critical...

Source: http://arxiv.org/abs/nlin/0210034v1

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48

Sep 19, 2013
09/13

by
Gautam I. Menon; Sudeshna Sinha; Purusattam Ray

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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...

Source: http://arxiv.org/abs/cond-mat/0208243v2

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Jul 22, 2013
07/13

by
Manish Dev Shrimali; Swarup Poria; Sudeshna Sinha

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It was observed that the spatiotemporal chaos in lattices of coupled chaotic maps was suppressed to a spatiotemporal fixed point when some fraction of the regular coupling connections were replaced by random links. Here we investigate the effects of different kinds of parametric fluctuations on the robustness of this spatiotemporal fixed point regime. In particular we study the spatiotemporal dynamics of the network with noisy interaction parameters, namely fluctuating fraction of random links...

Source: http://arxiv.org/abs/0807.0842v1

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3.0

Jun 30, 2018
06/18

by
Chandrakala Meena; Pranay Deep Rungta; Sudeshna Sinha

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We explore Random Scale-Free networks of populations, modelled by chaotic Ricker maps, connected by transport that is triggered when population density in a patch is in excess of a critical threshold level. Our central result is that threshold-activated dispersal leads to stable fixed populations, for a wide range of threshold levels. Further, suppression of chaos is facilitated when the threshold-activated migration is more rapid than the intrinsic population dynamics of a patch. Additionally,...

Topics: Chaotic Dynamics, Nonlinear Sciences

Source: http://arxiv.org/abs/1704.08506

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Sep 18, 2013
09/13

by
Kamal P. Singh; Rajeev Kapri; Sudeshna Sinha

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We demonstrate how the collective response of $N$ globally coupled bistable elements can strongly reflect the presence of very few non-identical elements in a large array of otherwise identical elements. Counter-intuitively, when there are a small number of elements with natural stable state different from the bulk of the elements, {\em all} the elements of the system evolve to the stable state of the minority due to strong coupling. The critical fraction of distinct elements needed to produce...

Source: http://arxiv.org/abs/1201.1083v1

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36

Sep 24, 2013
09/13

by
Neelima Gupte; T. M. Janaki; Sudeshna Sinha

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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...

Source: http://arxiv.org/abs/nlin/0205020v1

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27

Jul 19, 2013
07/13

by
S. M. Kamil; Gautam I. Menon; Sudeshna Sinha

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A variety of complex fluids under shear exhibit complex spatio-temporal behaviour, including what is now termed rheological chaos, at moderate values of the shear rate. Such chaos associated with rheological response occurs in regimes where the Reynolds number is very small. It must thus arise as a consequence of the coupling of the flow to internal structural variables describing the local state of the fluid. We propose a coupled map lattice (CML) model for such complex spatio-temporal...

Source: http://arxiv.org/abs/1005.2041v1

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41

Sep 23, 2013
09/13

by
S. M. Kamil; Sudeshna Sinha; Gautam I. Menon

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We propose and study a local map capable of describing the full variety of dynamical states, ranging from regular to chaotic, obtained when a nematic liquid crystal is subjected to a steady shear flow. The map is formulated in terms of a quaternion parametrization of rotations of the local frame described by the axes of the nematic director, subdirector and the joint normal to these, with two additional scalars describing the strength of ordering. Our model yields kayaking, wagging, tumbling,...

Source: http://arxiv.org/abs/0801.3876v2

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4.0

Jun 30, 2018
06/18

by
Sudhanshu Shekhar Chaurasia; Anshul Choudhary; Manish Dev Shrimali; Sudeshna Sinha

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We explore the dynamical consequences of switching the coupling form in a system of coupled oscillators. We consider two types of switching, one where the coupling function changes periodically and one where it changes probabilistically. We find, through bifurcation diagrams and Basin Stability analysis, that there exists a window in coupling strength where the oscillations get suppressed. Beyond this window, the oscillations are revived again. A similar trend emerges with respect to the...

Topics: Chaotic Dynamics, Nonlinear Sciences

Source: http://arxiv.org/abs/1701.07314

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2.0

Jun 29, 2018
06/18

by
Chiranjit Mitra; Anshul Choudhary; Sudeshna Sinha; Jürgen Kurths; Reik V. Donner

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Dynamical entities interacting with each other on complex networks often exhibit multistability. The stability of a desired steady regime (e.g., a synchronized state) to large perturbations is critical in the operation of many real-world networked dynamical systems such as ecosystems, power grids, the human brain, etc. This necessitates the development of appropriate quantifiers of stability of multiple stable states of such systems. Motivated by the concept of basin stability (BS) (Menck et...

Topics: Chaotic Dynamics, Nonlinear Sciences

Source: http://arxiv.org/abs/1612.06015

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Sep 21, 2013
09/13

by
K. Srinivasan; I. Raja Mohamed; K. Murali; M. Lakshmanan; Sudeshna Sinha

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A novel time delayed chaotic oscillator exhibiting mono- and double scroll complex chaotic attractors is designed. This circuit consists of only a few operational amplifiers and diodes and employs a threshold controller for flexibility. It efficiently implements a piecewise linear function. The control of piecewise linear function facilitates controlling the shape of the attractors. This is demonstrated by constructing the phase portraits of the attractors through numerical simulations and...

Source: http://arxiv.org/abs/1008.4011v1

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Sep 23, 2013
09/13

by
Edward H. Hellen; Syamal K. Dana; Jurgen Kurths; Elizabeth Kehler; Sudeshna Sinha

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We report the experimental verification of noise-enhanced logic behaviour in an electronic analog of a synthetic genetic network, composed of two repressors and two constitutive promoters. We observe good agreement between circuit measurements and numerical prediction, with the circuit allowing for robust logic operations in an optimal window of noise. Namely, the input-output characteristics of a logic gate is reproduced faithfully under moderate noise, which is a manifestation of the...

Source: http://arxiv.org/abs/1212.4470v2

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4.0

Jun 30, 2018
06/18

by
Behnam Kia; Sarvenaz Kia; John F. Lindner; Sudeshna Sinha; William L. Ditto

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We demonstrate how coupling nonlinear dynamical systems can reduce the effects of noise. For simplicity we investigate noisy coupled map lattices. Noise from different lattice nodes can diffuse across the lattice and lower the noise level of individual nodes. We develop a theoretical model that explains this observed noise evolution and show how the coupled dynamics can naturally function as an averaging filter. Our numerical simulations are in excellent agreement with the model predictions.

Topics: Nonlinear Sciences, Chaotic Dynamics

Source: http://arxiv.org/abs/1409.5186