The increasing demand for sensitive electrochemical sensors in various medical and industrial applications promotes the fabrication of novel sensing materials with improved electrocatalytic and analytical performances. This work deals with the development of a composite material based on gold nanoparticles (AuNPs) embedded in poly(3,4-ethylenedioxythiophene) (PEDOT) layer for electrochemical determination of caffeic acid (CA). CA is a phenolic compound with excellent antioxidant properties that is present in vegetables, fruits, and alcoholic and non-alcoholic beverages. Its analytical quantification is of great interest in food production monitoring and healthcare applications. Therefore, the development of sensitive analytical devices for CA monitoring is required. The AuNPs have been prepared in situ onto PEDOT coated glassy carbon electrode (GC) by means of an innovative procedure consisting on the use of a sinusoidal voltage (SV) superimposed on a constant potential. The physico-chemical properties of the PEDOT-AuNPs composite material were investigated by a range of techniques including cyclic voltammetry, electrochemical quartz crystal microbalance, and scanning electron microscopy. The glassy carbon electrode/poly(3,4-ethylenedioxythiophene)-gold nanoparticles-sinusoidal voltage (GC/PEDOT-AuNPs-SV) sensor exhibited good analytical performance toward the CA quantification with a linear response over a wide concentration range from 10 µM to 1 mM. In addition, the proposed GC/PEDOT-AuNPs-SV sensor was successfully applied in the determination of total polyphenols content expressed as equivalents of CA in juice samples.

This paper deals with the field-circuit type finite element analysis of the dynamic regimes of the threephase squirrel cage induction generator used in the isolated small power wind conversion systems.The numerical analysis of the squirrel cage induction generator using circuit models may lead to inaccurate results due to the usual simplifying hypotheses. This paper proposes a field-circuit model of the machine that is much more elaborated, being able to successfully take into account the complex specific phenomena such as: magnetic saturation, skin effect in the rotor bars, teeth harmonics etc.Among the dynamic regimes specific to the operation of the induction generator integrated in the isolated wind conversion systems, this paper is focused on the following aspects: self excitation phenomenon in case of open-circuit, three-phase short-circuit and dynamic response of the generator in case of load variations.

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