The influence of intermittent convection movements on electrochemical voltammograms is investigated. When the bath temperature rises to 315 K, the voltammograms exhibit irregular plateaus that differ for independent voltammetry scans, even when the setup is maintained under exactly the same conditions. In this paper, we show that such behavior can be caused by convection movements that develop in the electrolytic cell as a consequence of velocity fluctuations, since no bubbles or regular convective patterns are observed at this temperature. Theoretical current-potential curves for the heterogeneous deposition of metals on silicon electrodes is derived from a model consisting of a one-dimensional balance equation that includes diffusion, convection, and reaction through a time-dependent boundary condition. We obtain the current density associated with the adsorption of particles on the surface and, through this expression, we consider the effect of constant convective velocities on voltammograms. Finally, we examine the effect of random convective movements, described by a Monte Carlo algorithm that takes into account the random temporal fluctuations around a null convective current. The model predicts accentuated fluctuations on the current profiles, especially on the current plateaus that correspond to a stationary current regime. The validity of the theoretical model is checked against experimental data.

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This paper presents investigations laminated plates under moderately large transverse displacements and initial instability, through the Generalized Finite Element Methods-GFEM. The von Kármán plate hypothesis are used along with Kirchhoff and Reissner-Mindlin kinematic plate bending models to approximate transverse displacements and critical buckling loads. The generalized approximation functions are either C 0 or C k continuous functions, with k being arbitrarily large. It is well known that in GFEM, when both the partition of unity (PoU) and the enrichments functions are polynomials, the stiffness matrices are singular or ill conditioned, which causes additional difficulties in applications that requires the solution of algebraic eigenvalues problems, like in the determination of natural frequencies of vibration or the initial buckling loads. Some investigations regarding this problem are presently addressed and some aspects and advantages of using C k-GFEM are observed. In addition, comparisons are presented between the classical GFEM and the Stable-GFEM (SGFEM) with regard to the evaluation of the initial critical buckling loads. The numerical experiments use reference values from analytical and numerical results obtained in the open literature.