Publications

@article{Sharma2017,
title = {Time-delayed conjugate coupling in dynamical systems},
author = {Amit Sharma and Manish Dev Shrimali and Awadhesh Prasad and Ram Ramaswamy},
url = {https://ramramaswamy.org/papers/168.pdf},
doi = {10.1140/epjst/e2017-70026-4},
issn = {19516401},
year = {2017},
date = {2017-01-01},
journal = {European Physical Journal: Special Topics},
volume = {226},
number = {9},
pages = {1903–1910},
abstract = {textcopyright 2017, EDP Sciences and Springer-Verlag GmbH Germany. We study the effect of time-delay when the coupling between nonlinear systems is “conjugate”, namely through dissimilar variables. This form of coupling can induce anomalous transitions such as the emergence of oscillatory dynamics between regimes of amplitude death and oscillation death. The specific cases of coupled Landau-Stuart oscillators as well as a predator-prey model system with cross-predation are discussed. The dynamical behaviour is analyzed numerically and the regions corresponding to different asymptotic states are identified in parameter space.},
keywords = {Amplitude Death, Landau-Stuart, Oscillation Death, Time Delay},
pubstate = {published},
tppubtype = {article}
}

@article{Prasad2008b,
title = {The effect of time–delay on anomalous phase synchronization},
author = {A Prasad, J Kurths and R Ramaswamy},
url = {https://doi.org/10.1016/j.physleta.2008.08.043},
doi = {10.1016/j.physleta.2008.08.043},
year = {2008},
date = {2008-09-29},
journal = {Physics Letters A},
volume = {372},
number = {40},
pages = {6150-6154},
abstract = {Anomalous phase synchronization in nonidentical interacting oscillators is manifest as the increase of frequency disorder prior to synchronization. We show that this effect can be enhanced when a time-delay is included in the coupling. In systems of limit-cycle and chaotic oscillators we find that the regions of phase disorder and phase synchronization can be interwoven in the parameter space such that as a function of coupling or time-delay the system shows transitions from phase ordering to disorder and back.},
keywords = {Synchronization, Time Delay},
pubstate = {published},
tppubtype = {article}
}

@article{Azad2004,
title = {Symbol sequence analysis of climatic time signals},
author = {R Azad, J Subba Rao, and R Ramaswamy},
url = {https://doi.org/10.1016/j.nonrwa.2003.11.003},
doi = {10.1016/j.nonrwa.2003.11.003},
year = {2004},
date = {2004-07-01},
journal = {Nonlinear Analysis: Real World Applications },
volume = {5},
number = {3},
pages = {487-500},
abstract = {The conditional entropy of two symbolic sequences encoded faithfully from different chaotic time signal data is minimised at zero relative shift of the two signals if the signals have their origin in same underlying dynamics. We show that this minimum in conditional entropies E(Z/X) and E(X/Z) obtained after suitably ‘coarse–graining’ the time signals of, say, variables X and Z have marked differences depending upon the degree of dynamical coupling of the variables in the model. This technique has also been shown to be useful in studying delayed dependences of time signals. Application is made to climate data of four meteorological stations in India, namely New Delhi, Jaipur, Sundernagar and Chennai in order to determine (a) the commonality of underlying dynamics, (b) relative strength of dynamical coupling of different variables and (c) the delay implicit in the dynamics. The method appears robust to measurement noise.},
keywords = {climate, dynamical coupling, entropy, Time Delay},
pubstate = {published},
tppubtype = {article}
}