Effect of graphite oxide electrochemically exfoliated over a multimode interference filter.

In this work, we study multimodal interference filters with a graphite oxide coating. Use of the multimodal interference filter shows a distinctive peak in the signal spectrum, and when using the exfoliated graphite coated multimodal interference filter, the signal shows different spectral changes, such as the full width at half maximum of the curve, the maximum power, and central wavelength, which indicates that graphite oxide absorbs part of the energy. In addition, microscope observations when a He-Ne laser is passed through the filter confirm that graphite oxide is adhered to the filter.

Extensive study of shape and surface structure formation in the mercury beating heart system.

A phenomenological study of the mercury beating heart system in a three electrode electrochemical cell configuration forced with a harmonic perturbation is presented. The system is controlled via a potentiostat, where the mercury drop is electrically connected to a platinum wire and acts as the working electrode. This configuration exhibits geometrical shapes and complex surface structures when a harmonic signal is superimposed to the working electrode potential. This study involves a wide range of frequencies and amplitudes of the forcing signal. Differents levels of structure complexity are observed as a function of the parameters of the applied perturbation. At certain amplitudes and frequencies, rotational behavior is also observed.

Detecting bifurcations in an electrochemical cell employing an assisted reference model strategy.

Bifurcations are detected in experiments involving the electrochemical oxidation of copper in phosphoric acid. Ideally, a bifurcation detection protocol requires a model with good qualitative and quantitative prediction capabilities that is also able to reproduce the drift inherent to the electrochemical experiment. A generic protocol for manipulation of nonlinear systems is proposed to achieve this goal. This protocol is based on a good qualitative predictor coupled to a modified Kalman filter that corrects the quantitative errors of the model point by point, adapting to the slowly varying conditions imposed by the electrochemical drift.

Chaos induction using a reference model assisted control.

A stable period two orbit in the parametric vicinity of a chaotic attractor is prevented from being reached, via the exclusion of trajectories from its near vicinity using a reference model based control strategy. This results in the inception of sustained chaotic dynamics. The reference model control strategy includes a predictive term enabling delimitation of precluded zones for the system dynamics. This technique for promotion of chaotic behavior is illustrated by using an experimental electrochemical cell involving the potentiostatic electro-dissolution of copper in phosphoric acid.