Marcin Kapitaniak

Synchronous motion of two vertically excited planar elastic pendula

Abstract The dynamics of two planar elastic pendula mounted on the horizontally excited platform have been studied. We give evidence that the pendula can exhibit synchronous oscillatory and rotation motion and show that stable in-phase and anti-phase synchronous states always co-exist. The complete bifurcational scenario leading from synchronous to asynchronous motion is shown. We argue that our results are robust as they exist in the wide range of the system parameters.

Chaos in coupled clocks

We consider the dynamics of two pendulum clocks (with pendulums of the same length but different masses) suspended on the same beam. We give evidence that besides the complete and phase synchronizations, the considered system can exhibit long period synchronization and chaotic behavior. We argue that the observed phenomena are robust.

The three-dimensional dynamics of the die throw

A three-dimensional model of a die throw which considers the die bounces with dissipation on the fixed and oscillating table has been formulated. It allows simulations of the trajectories for dice with different shapes. Numerical results have been compared with the experimental observation using high speed camera. It is shown that for the realistic values of the initial energy the probabilities of the die landing on the face which is the lowest one at the beginning is larger than the probabilities of landing on any other face. We argue that non-smoothness of the system plays a key role in the occurrence of dynamical uncertainties and gives the explanation why for practically small uncertainties in the initial conditions a mechanical randomizer approximates the random process.

Synchronization Thresholds of Coupled Self-Excited Nonidentical Pendula Suspended on the Vertically Displacing Beam

The synchronization of a number of self-excited nonidentical pendula (with the same masses and different lengths) hanging on the same beam which can move vertically has been investigated. We identify different synchronous configurations and investigate their stability. An approximate analytical analysis of the energy balance allows to derive the synchronization conditions, phase difference between the pendula and explains the observed types of synchronizations. We give evidence of two thresholds (in a number of pendula and differences in lengths) after which the synchronization is not observed. It has been shown that for more than three pendula with sufficiently large differences in the lengths the synchronization is not observed and the pendula perform quasi-periodic oscillations. Our results are robust as they exist for the wide set of system parameters.

Synchronization extends the life time of the desired behavior of globally coupled systems

Synchronization occurs widely in natural and technological world, but it has not been widely used to extend the life time of the desirable behavior of the coupled systems. Here we consider the globally coupled system consisting of n units and show that the initial synchronous state extends the lifetime of desired behavior of the coupled system in the case when the excitation of one or few units is suddenly (breakdown of energy supply) or gradually (as the effect of aging and fatigue) switched off. We give evidence that for the properly chosen coupling the energy transfer from the excited units allows unexcited units to operate in the desired manner. As proof of concept, we examine the system of coupled externally excited rotating pendula. After the partial excitation switch off the initial complete synchronization of all pendula is replaced by phase synchronization with a constant phase shift between the clusters of excited and unexcited pendula. Our results show that the described extension of the systems life time occurs for the wide range of coupling parameters and is robust to the external perturbations.

Chaos and Hyperchaos in Coupled Antiphase Driven Toda Oscillators

The dynamics of two coupled antiphase driven Toda oscillators is studied. We demonstrate three different routes of transition to chaotic dynamics associated with different bifurcations of periodic and quasi-periodic regimes. As a result of these, two types of chaotic dynamics with one and two positive Lyapunov exponents are observed. We argue that the results obtained are robust as they can exist in a wide range of the system parameters.