Search results for "Impédance"
showing 4 items of 4 documents
Protonic ceramic fuel cell : elaboration and characterization. Investigation of the BaZr0.8Y0.2O3-d electrolyte by electrochemical impedance spectros…
2021
One of the current global challenges is to find novel, clean and efficient techniques for the energy production. The use of electrochemical cells and hydrogen is one of the solutions. These cells convert the excess energy produced by conventional systems into hydrogen by steam electrolysis. The hydrogen can be stored and transformed into electricity when needed in the fuel cell mode. Among the different electrochemical cells, protonic ceramic electrochemical cells have attracted much attention due to their high efficiency at intermediate temperature (400 – 600 °C). In addition, these systems offer the advantage of not diluting the fuel in electrolysis mode. This thesis work focuses on the e…
Conditioning metallic aluminum in magnesium phosphate cements
2016
This work deals with the stabilization / solidification of radioactive waste using cement.More particularly, it aims at assessing the chemical compatibility between metallic aluminum and mortars based on magnesium phosphate cement. The physical and chemical processes leading to setting and hardening of the cement are first investigated. X-ray diffraction (XRD), thermogravimetry (TGA) and nuclear magnetic resonance spectroscopy (31P and11B MAS-NMR) arefirst used to characterize the solid phases formed during hydration, while inductively coupled plasma atomic emission spectroscopy analysis (ICP-AES), electrical conductimetry and pH measurementsprovide information on the pore solution composit…
Modifications électrochimiques de surfaces et dispositifs électroniques organiques
2018
Organic electronics remains a fruitful research field thanks to the diversity of molecular structures reachable by organic synthesis. Molecular materials offer convenient shaping processes, such as solution processing techniques, which can be used for the fabrication of organic devices on plastic substrates.Our works can be summarized as the elaboration of conductometric devices thanks to electrochemistry and the study of their electrical and sensing properties. They deal with two topics: the development of new transducers based on substituted polyanilines and phthalocyanines and the study of the influence of electrochemical modifications on the behavior of known devices.We first developped…
Opérateur DtN pour les guides cylindriques à paroi traitée en présence d'un écoulement uniforme
2010
National audience; On s'intéresse au problème de rayonnement acoustique d'une source dans une conduite cylindrique axisymétrique infinie dont la paroi est recouverte d'un matériau absorbant en présence d'un écoulement uniforme. Dans le but d'utiliser la méthode des éléments finis, le domaine infini doit être tronqué par une frontière artificielle sur laquelle une condition limite transparente est introduite. La méthode exposée dans ce travail consiste à écrire la condition transparente sous la forme d'un opérateur Dirichlet to Neumann (DtN) obtenu par la généralisation de travaux réalisés dans le cas d'un guide 2D infini. Cet opérateur est basé sur une décomposition modale qu'il est facile …