Influence of temperature and applied potential on the permeability of polyphenol films prepared on vitreous carbon in acid and alkaline media

The electrochemical polymerization of phenol is known to rapidly produce a thin insulating film at the anode surface. This film generally blocks further polymerization. The objective of this study is to show that, depending on the operating conditions, polymeric films resulting from phenol oxidation present different properties and that certain films can be so porous that they allow the oxidation of phenol to continue. The deposition of polyphenol films with improved permeability could be attractive in the removal of phenol from polluted solutions. Polyphenol films were prepared in aqueous solution on a vitreous carbon anode either by cyclic voltammetry or by electro-oxidation at constant potential. The apparent permeability P (%) of the films prepared by these techniques was evaluated by monitoring changes in the electrode response towards phenol and potassium ferricyanide at 25 and 85 °C and as a function of the potential applied during electropolymerization performed either in acidic (1 mol L^?1 H₂SO₄) or in alkaline (1 mol L^?1 NaOH) aqueous solution. It was shown that: (1) the polyphenol film electrosynthesized in alkaline medium was more permeable than that prepared in acidic medium, (2) the apparent permeability was higher when the polyphenol film was electrosynthesized with simultaneous oxygen evolution and (3) the use of a high temperature in the polyphenol film preparation, especially in the presence of a concomitant oxygen evolution, significantly enhanced its apparent permeability (P ≥ 100 %). These results are interpreted in terms of a mixed-transport mechanism involving both pore and membrane diffusion. The effect of the permeability of the polymeric film on the removal of phenol from aqueous solution by electropolymerization is discussed.     

Robust behavioral modeling of dynamic nonlinearities using Gegenbauer polynomials with application to RF power amplifiers

In this article, we propose a new set of basis functions based on Gegenbauer polynomials suitable for robust behavioral modeling of nonlinear dynamic systems. These polynomials can be optimized for maximum model identification stability under different input signal distributions. The efficiency and robustness of the proposed polynomial models are demonstrated and compared to the ones of previously published models. The obtained results revealed an exceptional numerical stability regardless of the input signal statistics, making the proposed new models suitable for multimode and broadband nonlinear wireless transmitters. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:268–279, 2014.     

Electronic implementation of a PWM electrical nerve stimulation system for medical treatment of acute and chronic pains

In this paper we will implement a transcutaneous electrical nerve stimulation (TENS) designed for medical applications in order to reduce acute and chronic pains. This procedure uses electrical currents pulses applied on the skin area via electrodes. Two kinds of stimulation are adopted: the peripheral nerve stimulation (PNS) and the spinal cord stimulation (SCS). In either, a small pulse generator sends electrical pulses to the nerves (in PNS stimulation) or to the spinal cord (SCS stimulation). Previous studies on TENS technique showed that the obtained results are not very satisfactory and depend on the patient’s state, condition, age, and stimulation parameters. In order to optimize the conditions and parameters stimulation during treatments, we present in this paper a new strategy called pulse width modulation stimulation (PWM-TENS) based on a parametric computing of frequency, current intensity, pulse duration of stimuli. To implement our approach, we used an embedded platform under Arduino-Uno with five several programs depending on the pain category and according to international medical standards and specifications. The first tests on 15 volunteer patients showed satisfaction ratio (EVA) after 5–12 days and a pain reduction between 80 and 20 after 1 month of stimulation. This result is important because it prolongs the analgesic effect and reduces therapeutic rehabilitation period. The medical aspect of the subject is to have a medical tool that allows objective evaluations for short and medium periods of pain treatments with dynamic evaluation metrics.     

On the lattice of specifications: Applications to a specification methodology

In this paper we investigate the lattice properties of the natural ordering between specifications, which expresses that a specification expresses a stronger requirement than another specification. The lattice-like structure that we uncover is used as a basis for a specification methodology.     

Improvement of DV-Hop localization algorithm for randomly deployed wireless sensor networks

Telecommunication Systems - The Distance Vector-Hop (DV-Hop) algorithm is a well-known technique for wireless sensor networks node location due to its robustness, simplicity and cost effectiveness....     

Seismic noise attenuation by means of an anisotropic non-linear diffusion filter

Noise attenuation is a major seismic data processing concern. In seismic data, noise can appear as random, coherent and/or impulsive. Recently, many different techniques, ranging from relatively simple processes to extremely complex ones, have been used for noise attenuation. Image filtering techniques are relatively new methods in seismic exploration. We introduced the anisotropic non-linear diffusion filter which is an effective way to de-noise images. Since a seismic section can be considered as an image of a two-variable function, we implemented the anisotropic non-linear diffusion filter to reduce both random and Gaussian noises. This filter is shown to be effective in removing noise while preserving edges and hence reducing resolution loss in seismic data. The anisotropic non-linear diffusion filter, with Tukey's function to guide the diffusivity, was applied to synthetic and real seismic data. The results show a signal-to-noise ratio increase with reflector continuity in addition to better recovery of reflector amplitudes even when dealing with complex subsurface geological structures.