Vilmos Gáspár

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We report numerical and experimental results indicating successful stabilization of unstable steady states and periodic orbits in an electrochemical system. Applying a continuous delayed-feedback technique not only periodic and chaotic oscillations are suppressed via stabilization of steady-state solutions but also the chaotic dynamics can be converted to(More)
Experimental results are presented on successful application of delayed-feedback control algorithms for tracking unstable steady states and periodic orbits of electrochemical dissolution systems. Time-delay autosynchronization and delay optimization with a descent gradient method were applied for stationary states and periodic orbits, respectively. These(More)
Chaotic systems are highly susceptible to control by using small perturbations to a system constraint. Feedback methods have been applied to taming chaos in magnetoelastic and hydrodynamic systems, electric circuits, lasers, chemical reactions, and tissues of heart and brain in vitro.1 The well-known Ott-Grebogi-Yorke (OGY) algorithm2 and its variations are(More)
Dynamics of oscillations in electrochemical systems are affected by both chemical and physical properties of the systems. Chemical properties include the type of electrochemical reaction, the electrode material, the composition of the electrolyte, etc., while physical properties include the solution resistance, the cell constant, the electrode size, the(More)
An experimentally accessible algorithm for changing the time scale associated with a dynamical variable is proposed. In general, a differential controller can be applied to (a) identify the essential species in oscillatory systems and (b) explore their role in the feedback loops. Here, we report on classifying electrochemical oscillators by changing the(More)
Experiments were carried out on synchronization and control of complex chaotic dynamics observed during the dissolution of two and four coupled nickel electrodes in sulfuric acid under potentiostatic conditions. In a given potential range the individually measured currents exhibit asynchronous chaotic oscillations. The complexity (as measured by the(More)
We report experimental control of complex (periodic and chaotic) oscillatory dynamics in an electrochemical system by applying a nonfeedback control method. By choosing an appropriate frequency for the periodic modulation of an accessible control parameter (e.g., circuit potential) not only are the chaotic dynamics converted to regular periodic behavior(More)
The chaotic evolution in the combustion of CO in a well-stirred flow reactor is controlled experimentally using a modified form of the simple proportional feedback (SPF) algorithm. An unstable period-1 oscillation is stabilized through the imposition of small, appropriate perturbations which are calculated from the observed experimental response of the(More)
Occurrence of bi- and trirhythmicities (coexistence of two or three stable limit cycles, respectively, with distinctly different periods) has been studied experimentally by applying delayed feedback control to the copper-phosphoric acid electrochemical system oscillating close to a Hopf bifurcation point under potentiostatic condition. The oscillating(More)
Impedance spectroscopy is applied to quantitatively characterize the bifurcations leading to current oscillations during anodic dissolution of a copper rotating-disk electrode in sodium acetate-glacial acetic acid and o-phosphoric acid electrolytes under potentiostatic control. The line of Hopf bifurcations in a diagram spanned by the uncompensated series(More)