Sudeshna Sinha 《Europhysics letters》2019,128(4)

We study the dynamics of coupled systems,ranging from maps supporting chaotic attractors to nonlinear differential equations yielding limit cycles,under different coupling classes,connectivity ranges and initial states. Our focus is the robustness of chimera states in the presence of a few time-varying random links,and we demonstrate that chimera states are often destroyed,yielding either spatiotemporal fixed points or spatiotemporal chaos,in the presence of even a single dynamically changing random connection. We also study the global impact of random links by exploring the Basin Stability of the chimera state,and we find that the basin size of the chimera state rapidly falls to zero under increasing fraction of random links. This indicates the extreme fragility of chimera patterns under minimal spatial randomness in many systems,significantly impacting the potential observability of chimera states in naturally occurring scenarios.https://doi.org/10.1209/0295-5075/128/40004  相似文献   

    

M. Anvari;M. Wächter;J. Peinke 《Europhysics letters》2016,116(6)

Wind energy, inserted into the power grid by wind turbines, is strongly influenced by the turbulent fluctuations of wind speed in the atmospheric layer. Here we investigate the power production of a wind farm and show that due to the presence of large-scale and long-time correlation in wind velocity, turbines interact with each other. This interaction can result in phase locking in pairs of turbines. We show that there are time intervals during which some pairs of turbines are temporally phase locked. This intermediate phase locking leads to the statistical effect that the short-time fluctuations of the cumulative power output of the wind farm become non-Gaussian, i.e., intermittent power production occurs. Contrary to phase-locked states, there are some time intervals where all turbines are phase unlocking and consequently the probability density function of the temporal increment of cumulative power production of the wind farm has almost Gaussian distribution. The phase-locked states, which can be distinct from phase-unlocked states by their dynamical features, are evaluated by reconstructed stochastic differential equations.https://doi.org/10.1209/0295-5075/116/60009  相似文献   

    

B. Subash;V. K. Chandrasekar;M. Lakshmanan 《Europhysics letters》2015,109(1)

We demonstrate that the synchronization of an array of electrically coupled spin torque nano-oscillators (STNO) modelled by Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation can be enhanced appreciably in the presence of a common external microwave magnetic field. The applied microwave magnetic field stabilizes and enhances the regions of synchronization in the frequency determining parameter space. We have identified two regions of synchronization in the parameter space of our analysis, where the oscillators are exhibiting synchronized oscillations thereby emitting improved microwave power. To characterize the synchronized oscillations we have calculated the locking range in the domain of external source frequency.https://doi.org/10.1209/0295-5075/109/17009  相似文献   

    

N. Semenova;A. Zakharova;E. Schöll;V. Anishchenko 《Europhysics letters》2015,112(4)

We analyze nonlocally coupled networks of identical chaotic oscillators with either time-discrete or time-continuous dynamics (Henon map, Lozi map, Lorenz system). We hypothesize that chimera states, in which spatial domains of coherent (synchronous) and incoherent (desynchronized) dynamics coexist, can be obtained only in networks of oscillators with nonhyperbolic chaotic attractors and cannot be found in networks of systems with hyperbolic chaotic attractors. This hypothesis is supported by analytical results and numerical simulations for hyperbolic and nonhyperbolic cases.https://doi.org/10.1209/0295-5075/112/40002  相似文献   

    

Junhong Li;Bangpin Hou;Yonghong Zhao;Lianfu Wei 《Europhysics letters》2015,110(6)

We investigate the entanglement between two movable mirrors in an optomechanical cavity, in which a Kerr-down-conversion crystal consisting of a Kerr nonlinear medium and an optical parametric amplifier (OPA) is placed. The effects of the nonlinear media on the entanglement have been analyzed. It is shown that the Kerr nonlinear medium makes the perfect entanglement in some discrete frequency regions. Furthermore, when the input vacuum field is squeezed, the frequency range for producing the entanglement can be effectively extended and the reachable maximal entanglement can be enhanced by the Kerr nonlinear medium, while the OPA medium reduces the degree of the entanglement and necks the frequency range for generating the entanglement. These results suggest that nonlinear media could serve as a new handle to coherently control the entanglement between the vibrational modes of the micromirrors in the optomechanical cavity system.https://doi.org/10.1209/0295-5075/110/64004  相似文献   

    

G. S. M. Ngueuteu;R. Yamapi;P. Woafo 《Europhysics letters》2015,112(3)

We investigate quenching oscillations phenomena in a system of two diffusively and mutually coupled identical fractional-order Stuart-Landau oscillators. We first consider the uncoupled unit and find that the stabilizing virtue of the fractional derivative yields suppression of oscillations via a Hopf bifurcation. The oscillatory solutions of the fractional-order Stuart-Landau equation are provided as well. Quenching phenomena are then investigated in the coupled system. It is found that the fractional derivatives enhance oscillation death by widening its domain of existence in coupling strength space and initial conditions space, leading to oscillation death dominance. A region of stable homogeneous steady state appears where the uncoupled oscillators are resting and not oscillating as usually accepted for the realization of amplitude death.https://doi.org/10.1209/0295-5075/112/30004  相似文献   

    

Darka Labavić;Hildegard Meyer-Ortmanns 《Europhysics letters》2015,109(1)

We study the mutual conversion of regimes of collective fixed-point behavior and collective synchronized oscillations in a system of coupled dynamical units, which individually can be in an excitable or oscillatory state. The conversion is triggered by the change of a single bifurcation parameter. Of particular interest is the arrest of oscillations. We identify the criterion that determines the seeds of arrest and the propagation of arrest fronts in terms of the vicinity to the future attractor. Due to a high degree of multistability we observe versatile patterns of phase locked motion in the oscillatory regime. Quenching the system into the regime, where oscillatory states are metastable, we observe qualitatively distinct approaches of the fixed-point attractor, depending on the initial seeds. If the seeds of arrest are isolated single sites of the lattice, the arrest propagates via bubble formation, visually similar to nucleation processes; if the seed is extended along a line of lowest amplitudes, the freezing follows the spatial patterns of phase-locked motion with long interfaces between arrested and oscillating units. For spiral patterns of oscillator phases these interfaces are arranged along the arms of the spirals.https://doi.org/10.1209/0295-5075/109/10001  相似文献   

    

R. F. Mikalsen;B. C. Hagen;V. Frette 《Europhysics letters》2018,121(5)

Synchronized,pulsating temperatures are observed experimentally in smoldering fires. The entire sample volume (1.8 l) participates in the pulsations (pulse period 2–4 h). The synchrony lasts up to 25 h and is followed by a spontaneous transition to either disordered combustion or self-extinguishment. The synchronization is obtained when the fuel bed is cooled to the brink of extinguishment. Calculations for adiabatic conditions,including heat generation from combustion (nonlinear in temperature) and heat storage in sample (linear in temperature),predict diverging sample temperature. Experimentally,heat losses to surroundings (linear in temperature) prevent temperatures to increase without bounds and lead to pulsations.https://doi.org/10.1209/0295-5075/121/50002  相似文献   

    

Zhouchao Wei;Fatemeh Parastesh;Hamed Azarnoush;Sajad Jafari;Dibakar Ghosh;Matjaž Perc;Mitja Slavinec 《Europhysics letters》2018,123(4)

Chimeras are special states that are composed of coexisting spatial domains of coherent and incoherent dynamics, which typically emerge in identically coupled oscillators. In this paper, we study a network of nonlocally coupled Hindmarsh-Rose neurons that are subject to an alternating current. We show that chimera states emerge when the neurons are connected through electrical synapses. The considered model has two coexisting attractors, namely a limit cycle and a chaotic attractor, to which the dynamics converges in dependence on the initial conditions. While earlier research reported the existence of chimeras in Hindmarsh-Rose neuronal networks mainly through chemical synapses, here we show that an alternating current in an electrically coupled network can also evoke chimeras, whereby the spatial positions of coherent and incoherent domains vary with time. Remarkably, we also observe chimera states in locally coupled neurons through electrical synapses, which reduce the relaxation of nonlocallity in the coupling configuration. The existence of nonstationary chimeras is confirmed by means of a local order parameter.https://doi.org/10.1209/0295-5075/123/48003  相似文献   

    

M. Winkler;J. Sawicki;I. Omelchenko;A. Zakharova;V. Anishchenko;E. Schöll 《Europhysics letters》2019,126(5)

Complex multiplex networks consist of several subnetwork layers,which interact via pairwise inter-layer connections. Relay synchronization between distant layers which are not directly connected,but only via a relay layer,can be observed in multiplex networks. We study three-layer networks of discrete logistic maps,where each individual layer is a nonlocally coupled ring,and demonstrate scenarios of relay synchronization of complex patterns in the outer layers which interact via an intermediate layer. We find regimes of relay synchronization for chimera states,i.e.,patterns of coexisting coherent and incoherent domains,and a transition from phase chimeras to amplitude chimeras for increasing inter-layer coupling. We determine analytically the approximate critical coupling strengths for the existence of phase chimeras.https://doi.org/10.1209/0295-5075/126/50004  相似文献