International Journal of Bifurcation and Chaos

More than one third of the 88 globally-independent Cellular Automata rules exhibit robust simple Bernoulli-shift dynamics. Among them we find rule , which we proved to be chaotic in the previous episodes of our chronicle, and rule , the famous global majority rule. Therefore, we cannot overstate the importance of the Bernoulli σ_τ-shift rules which we will present in two parts of our continuing odyssey on the Nonlinear Dynamics Perspective of Cellular Automata. This paper covers the first 15 of the 30 Bernoulli σ_τ-shift rules. In this paper, after recalling the main concepts of Bernoulli rules — such as the role of the three Bernoulli parameters σ, τ and β — we will display the basin tree diagrams of these rules together with a convenient summary of the results extracted from them. Then, we will show that the superstring is an excellent testing signal to find the robust behavior of a given rule. Finally, we will conclude this paper with a discussion about the difference between robust and nonrobust ω-limit orbits of the Bernoulli σ_τ-shift rules.

Stickiness refers to chaotic orbits that stay in a particular region for a long time before escaping. For example, stickiness appears near the borders of an island of stability in the phase space of a 2-D dynamical system. This is pronounced when the KAM tori surrounding the island are destroyed and become cantori (see [Contopoulos, 2002]). We find the time scale of stickiness along the unstable asymptotic curves of unstable periodic orbits around an island of stability, that depends on several factors: (a) the largest eigenvalue |λ| of the asymptotic curve. If λ > 0 the orbits on the unstable asymptotic manifold in one direction (fast direction) escape faster than the orbits in the opposite direction (slow direction) (b) the distance from the last KAM curve or from the main cantorus (the cantorus with the smallest gaps) (c) the size of the gaps of the main cantorus and (d) the other cantori, islands and asymptotic curves. The most important factor is the size of the gaps of the main cantorus. Then we find when the various KAM curves are destroyed. The distance of the last KAM curve from the center of an island gives the size of the island. When the central periodic orbit becomes unstable, chaos is also formed around it, limited by a first KAM curve. Between the first and the last KAM curves there are still closed invariant curves. The sizes of the islands as functions of the perturbation, have abrupt changes at resonances. These functions have some universal features but also some differences. A new type of stickiness appears near the unstable asymptotic curves of unstable periodic orbits that extend far into the large chaotic sea. Such a stickiness lasts for long times, increasing the density of points close to the unstable asymptotic curves. However after a much longer time, the density becomes almost equal everywhere outside the islands of stability. We consider also stickiness near the asymptotic curves from new periodic orbits, and stickiness in Anosov systems and near totally unstable orbits. In systems that allow escapes to infinity the stickiness delays the escapes. An important astrophysical application is the case of barred-spiral galaxies. The spiral arms outside corotation consist mainly of sticky chaotic orbits. Stickiness keeps the spiral forms for times longer than a Hubble time, but after a much longer time most of the chaotic orbits escape to infinity.

We recall three well-known theorems related to the simplest codimension-one bifurcations occurring in discrete time dynamical systems, such as the fold, flip and Neimark–Sacker bifurcations, and analyze these bifurcations in presence of certain degeneracy conditions, when the above mentioned theorems are not applied. The occurrence of such degenerate bifurcations is particularly important in piecewise smooth maps, for which it is not possible to specify in general the result of the bifurcation, as it strongly depends on the global properties of the map. In fact, the degenerate bifurcations mainly occur in piecewise smooth maps defined in some subspace of the phase space by a linear or linear-fractional function, although not necessarily only by such functions. We also discuss the relation between degenerate bifurcations and border-collision bifurcations.

In this study, we present results concerning seismogenesis in the Hellenic region (land and sea of Greece), applying nonlinear analysis to an earthquake time series. The model of the dripping faucet is used as a physical interpretation of the seismic process and the construction of inter-event seismic time series. Geometrical and dynamical characteristics estimated in the reconstructed state space support the low dimensional, chaotic character of the global seismic process in the Hellenic region. The method of stochastic surrogate data was employed to the exclusion of "pseudo chaos" caused by the nonlinear distortion of a purely stochastic process. These results are in agreement with general theoretical models concerning distributed driven threshold dynamics applied to the case of seismic processes. Moreover, the observed global character of low dimensionality and chaoticity over such a complex system of faults supports the hypothesis that seismogenesis is characterized by spatiotemporal intermittent chaos throughout the Hellenic region.

In this work some complex behaviors of a controlled reverse flow reactor is presented. The control system introduces discrete events making the model an infinite dimensional hybrid system. The study is conducted through continuation techniques and brute force numerical simulations. Together with standard bifurcations like pitchfork, saddle-node and Neimark–Sacker, varying the set-point parameter of the controller, several novel aspects are singled out: an unusual sequence of period-adding bifurcation phenomena, a new route to chaos and the coexistence of Zeno states with quasi-periodic and chaotic regimes. The period-adding phenomena dictate the transition between symmetric and asymmetric multiperiodic regimes and a simple rule for the occurrence of symmetry breaking and recovery is found. The new route to chaos is a transition from a quasi-periodic regime to chaos due to the presence of Zeno phenomena, typical of hybrid systems. The chaos is characterized by Zeno-like oscillations.

A complex processing of the dynamic programming is implemented with the parallel architecture of Cellular Neural Networks. Dynamic programming is an efficient algorithm to find optimal path and Cellular Neural Network is a parallel computation architecture composed of identical computation cell array and identical connections at each cell. Breaking down complex processing of the dynamic programming into a sequence of simple steps, the dynamic programming algorithm can be built with the nonlinear templates of Cellular Neural Networks. The procedure to breakdown the complex computation into the sequence of CNN building blocks is illustrated. To show the feasibility of the proposed method, the designed CNN-based dynamic programming is applied for detecting the traces of road boundaries. Edge information of road image is extracted and assigned as local distance value accordingly, then dynamic programming algorithm is implemented by a nonlinear CNN template. The proposed algorithm and its possible circuit structure are described, and simulation results are reported.

In this letter, we investigate the stationary solutions of multiple output levels RTD-based cellular neural networks (CNN) by using Chua's driving-point plot methods. Moreover, we present some sufficient conditions, that are concise and easy to be validated, to determine the existence of the stationary solutions. Finally, we give four illustrative examples to show the effectiveness of our results.

The identification problem for excitable media is investigated in this paper. A new scalar coupled map lattice (SCML) model is introduced and the orthogonal least squares algorithm is employed to determinate the structure of the SCML model and to estimate the associated parameters. A simulated pattern and a pattern observed directly from a real Belousov–Zhabotinsky reaction are identified. The identified SCML models are shown to possess almost the same local dynamics as the original systems and are able to provide good long term predictions.

Recently, the synchronization issue in chaotic systems has become a hot topic in nonlinear dynamics and has aroused great interest among researchers due to the theoretical significance and potential applications. In this paper, complete periodic synchronization is considered for the delayed neural networks with discontinuous activation functions. Under the framework of Filippov solution, a novel control method is presented by using differential inclusions theory, nonsmooth Lyapunov method and linear matrix inequality (LMI) approach. Based on a newly obtained necessary and sufficient condition, several criteria are derived to ensure the global asymptotical stability of the error system, and thus the response system synchronizes with the drive system. Moreover, the estimation gains are obtained. With these new and effective methods, complete synchronization is achieved. Simulation results are given to illustrate the theoretical results.

This paper provides a unified approach for achieving and analyzing global synchronization of a class of master-slave coupled multiscroll chaotic systems under linear state-error feedback control. A general mathematical model for such a class of multiscroll chaotic systems is first established. Based on some special properties of such systems, two less-conservative frequency-domain criteria for the desirable global synchronization are rigorously proven by means of the absolute stability theory. The analysis is then applied to two master-slave coupled modified Chua's circuits, obtaining the corresponding simple and precise algebraic criteria for global synchronization, which are finally verified by numerical simulations.

We numerically study the synchronization of two nonidentical pendulum motions, pivoting on a common movable frame from the point of view of dynamic phase transition. When the difference in the pendulum lengths is not too large, it is shown that the system settles into the dynamic state of the antiphase synchronization with phase difference π. We observe that there is a bistable region where either the antiphase synchronized state or the desynchronized state can be stabilized. We also find that there exists a hysteresis effect around the dynamic phase transition as the length difference is adiabatically changed.

We propose a very simple implementation of a second-order nonautonomous chaotic oscillator, using a threshold controller as the only source of nonlinearity. We demonstrate the efficacy and simplicity of our design through numerical and experimental results. Further, we show that this approach of using a threshold controller as a nonlinear element, can be extended to obtain autonomous and multiscroll chaotic attractor circuits as well.

Spatiotemporal chaotic systems have been applied to design pseudo-random-bit generators or ciphers for better cryptographic performance, where spatiotemporal chaos is desirable. This paper presents a chaotification method (or anti-chaos control) for creating spatiotemporal systems, which are originally either nonchaotic or chaotic, strongly chaotic. Sufficient conditions on the system parameters for chaotification are obtained. A mathematically rigorous proof shows that the chaotified system satisfying the parameter conditions is chaotic in the sense of Li–Yorke and Devaney, respectively. Moreover, the chaotification method is applicable to other spatiotemporal systems even with different configurations. Simulation results have illustrated the effectiveness of the proposed chaotification method. Additionally, the statistical properties of the spatiotemporal systems and their chaotified counterparts are analyzed and compared, showing that the chaotification method endows the spatiotemporal systems with good statistical properties. Therefore, the chaotification method can be used for applications of spatiotemporal systems in cryptography.

A simple approach for generating (2N + 1)-scroll chaotic attractor from a modified Colpitts oscillator model is proposed in this paper. The key strategy is to increase the number of index-2 equilibrium points by introducing a triangle function to directly replace the nonlinearity term of Colpitts oscillator model. The dynamical characteristics of the new multiscroll chaotic system are studied comprehensively. A circuit realization structure is introduced and the experimental results demonstrate that (2N + 1)-scroll chaotic attractors can be obtained in practical circuit.

This paper considers the critical periods of third-order planar Hamiltonian systems. It is assumed that the origin of the system is a center. With the aid of symbolic and numerical computations, we show the existence of seven local critical periods. This is the maximal number of local critical periods that a cubic Hamiltonian system can have.

The dynamics of the curlicue curves with memory endowed in their dynamics is addressed in this study.

In our recent letter [de Lacy Costello et al., 2009] we described the formation of spontaneous complex tessellations of the plane constructed in simple chemical reactions between drops of metal salts and ferricyanide or ferrocyanide loaded gels. In this paper, we provide more examples of binary tessellations and extend our analysis to tessellations constructed via tertiary mixtures of reactants. We also provide a classification system which describes the tessellation based on the reactivity of the metal salt with the substrate and also the cross-reactivity of the primary products. This results in balanced tessellations where both reactants have equal reactivity or unbalanced tessellations where one reactant has a lower reactivity with the gel. The products can also be partially or fully cross reactive which gives a highly complex tessellation.

The tessellations are made up of colored cells (corresponding to different metal ferricyanides or ferrocyanides) separated by bisectors of low precipitate concentration. The tessellations constructed by these reactions constitute generalized Voronoi diagrams. In the case of certain binary or tertiary combinations of reactants where the diffusion/reaction rates differ, then multiplicatively weighted crystal growth Voronoi diagrams are constructed. Where one reactant has limited or no reactivity with the gel (or the products are cross reactive) then the fronts originating from the reactive metal ions cross the fronts originating from the partially reactive metal ions. The fronts can annihilate in the formation of a second Voronoi diagram relating to the relative positions of the reactive drops. Therefore, two or more generalised or weighted Voronoi diagrams can be calculated in parallel by these simple chemical systems.

However when these reactions were used to calculate an additively weighted Voronoi diagram (the reaction was initiated at different time intervals) the diagram constructed did not correspond to the theoretical calculation. We use the failure of these reactions to construct an additively weighted Voronoi diagram to prove a mechanism of substrate competition for bisector formation.

These tessellations are an important class of pattern forming reactions and are useful in modeling natural pattern forming phenomena in addition to being a great resource for scientific demonstrations.