Ricerc@Sapienza

The doubly-fed induction machine has long been reputed as a curiosity with few practical applications. Consequently, very often there was not enough space to treat this machine in undergraduate electrical machines curricula in the past. But times changed and today this machine is often an integral part of wind turbines as electric generator. This way, getting familiar with the relevant operating principles becomes a desirable task for undergraduate students. This paper proposes a circuit-based theoretical approach which may serve as a template for an undergraduate lecture.

The present contribution reports on the analysis of the electrochemical properties of screen-printed nickel oxide (NiO) in aqueous electrolyte when NiO is in the configuration of thin film (thickness, l ≤ 7 μm). This type of NiO samples presents mesoscopic morphology. The latter characteristic combined to the intrinsic electroactivity of the oxide leads to the observation of proportionality between NiO thickness and current density. In particular, NiO undergoes two distinct processes of oxidation with reversible features in aqueous media.