We observe chimeralike states in an ensemble of oscillators using a type of global coupling consisting of two components: attractive and repulsive mean-field feedback. We identify existence of two types of chimeralike states in a bistable Liénard system; in one type, both the coherent and the incoherent populations are in chaotic states (called as chaos-chaos chimeralike states) and, in another type, the incoherent population is in periodic state while the coherent population has irregular small oscillation. Interestingly, we also recorded a metastable state in a parameter regime of the Liénard system where the coherent and noncoherent states migrates from one to another population. To test the generality of the coupling configuration, we present another example of bistable system, the van der Pol-Duffing system where the chimeralike states are observed, however, the coherent population is periodic or quasiperiodic and the incoherent population is of chaotic in nature. Furthermore, we apply the coupling to a network of chaotic Rössler system where we find the chaos-chaos chimeralike states.
An array of excitable Josephson junctions under global mean-field interaction and a common periodic forcing shows emergence of two important classes of coherent dynamics, librational and rotational motion in the weaker and stronger coupling limits, respectively, with transitions to chimeralike states and clustered states in the intermediate coupling range. In this numerical study, we use the Kuramoto complex order parameter and introduce two measures, a libration index and a clustering index to characterize the dynamical regimes and their transition and locate them in a parameter plane.PACS numbers: 05.45.Xt, 05.45.Gg A surprising new phenomenon was reported in the last decade, namely, the chimera states [1][2][3][4][5][6][7][8] that emerge via a symmetry breaking of a homogeneous synchronous state in a large population of nonlocally coupled identical phase oscillators into two coexisting spatially extended coherent and noncoherent subpopulations. Presently, existence of chimera states has been reported in identical limit cycle oscillators [8,9], chaotic systems [9-13] and very recently in excitable systems in presence of noise [14]. It drew special attention after noticing a similar behavior in the brain of some sleeping animals [15]. It has been now confirmed in laboratory experiments [16][17][18]. Most surprisingly, chimeralike states were observed in globally coupled network of identical oscillators [19][20][21][22][23] which was unexpected because of the presence of a perfect symmetry in such a network. The reason of symmetry breaking of a homogeneous state into coexisting coherent and nocoherent states still remains a puzzle.In We report a search, in this paper, for chimera states in a Josephson junction array under global mean-field interaction if they exist at all and under what conditions? The existence of a state of order and turbulence was reported earlier [30] in a forced Josephson junction array under global mean-field influence, which showed signatures of chimera states, however, no categorical statement was made at that time. We revisit that parameter space of the Josephson junction array under the same condition and confirm existence of chimeralike states. In the process, we notice two important classes of coherent states, one regular librational motion and a regular rotational motion in the array, which are typical dynamical features [32] of a single Josephson junction. In cylindrical space [37], the trajectory of a junction is localized during a libration while it encircles the cylinder during a rotational motion (Fig. 4). Most importantly, we observe a transition between the two coherent states for changing coupling interaction. Increasing the coupling strength from a weaker range, the coherent librational motion emerges above a threshold and continues for a range of coupling, then transits to coherent rotational motion for large coupling via successive chimeralike states and clusarXiv:1612.08557v1 [nlin.CD]
A void (i.e. the complete absence of macroscopic dust particles) can be generated in the bulk plasma region of a cogenerated dusty plasma with the help of a positively dc-biased ring electrode placed between two electrodes of dc discharge. This void region can then be dynamically controlled by varying the external positive bias voltage through the ring electrode.
An experimental observation of spatiotemporal evolution of dust density waves (DDWs) in cogenerated dusty plasma in the presence of modified field induced by glass plate is reported. Various DDWs, such as vertical, oblique, and stationary, were detected simultaneously for the first time. Evolution of spatiotemporal complexity like bifurcation in propagating wavefronts is also observed. As dust concentration reaches extremely high value, the DDW collapses. Also, the oblique and nonpropagating mode vanishes when we increase the number of glass plates, while dust particles were trapped above each glass plates showing only vertical DDWs.
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