1,721,112 research outputs found
Multiscale characterization of thin films elasticity by Impulse Excitation Technique and X-ray diffraction
No full textLes dépôts élaborés par pulvérisation cathodique magnétron sont généralement polycristallins, texturés et composés de différentes phases. De plus, plusieurs études ont montré que le comportement élastique des couches minces dépend des paramètres du procédé. L’objectif de cette thèse est de développer une méthodologie qui permet de déterminer les constantes d’élasticité d’un dépôt à une échelle macroscopique et mésoscopique (cristal). La méthodologie développée dans ce travail a permis de déterminer les constantes d’élasticité macroscopiques d’une couche mince de tungstène biphasé (Wα+Wβ) et les constantes d’élasticité mésoscopiques de la phase Wβ . Le comportement élastique de cette phase n’est pas connu dans la bibliographie ce qui motive la présente étude. Les constantes d’élasticité macroscopiques ont été mesurées à l’aide de la Technique d’Excitation Impulsionnelle (TEI). Une étude métrologique de cette méthode a été effectuée puis une formulation améliorée pour déterminer le module de cisaillement a été proposée. Les constantes d’élasticité mésoscopiques de la phase métastable Wβ ont été déterminées par une méthode inverse couplant TEI, diffraction des rayons-X, et le modèle micromécanique de Kröner-Eshelby. La démarche a pris en compte les proportions des phases, leur texture et la présence de porosités.Thin films deposited by magnetron sputtering are generally polycristalline, textured and composed of different phases. Several works have shown that the elastic behavior of thin films depends on the deposition parameters. In this work a methodology to determine the macroscopic and mesoscopic elasticity constants of thin films was developed. It was used to determine the macroscopic elasticity constants of a two-phases (Wα+Wβ) tungsten coating and the mesoscopic (crystal scale) elasticity constants of the Wβ phase. The main motivation on studying the metastable Wβ tungsten phase is the absence of information on its elastic behavior in the literature. The macroscopic elasticity constants were measured using the Impulse Excitation Technique (IET). A metrological study of this method was performed and a new formulation to determine the shear modulus was proposed. The mesoscopic elasticity constants of the Wβ phase were determined through an inverse method coupling IET, X-ray diffraction and the Kröner-Eshelby micromechanical model. The proportions and the textures of the phases were taken into account in the process, along with the presence of porosity
Development of sustainable architectural coatings produced by hybrid PVD and ALD technologies
No full textL’objectif de cette thèse est de développer une nouvelle génération des couches minces duplex par la combinaison hybride des techniques de pulvérisation cathodique magnétron et de dépôt de couches atomiques. La structure, la morphologie, le comportement mécanique et les propriétés électrochimiques des revêtements ont été évaluées. Différentes architectures de revêtements hybrides : ALD/PVD, PVD/ALD et PVD/ALD/PVD ont été étudiées. L’étude a été réalisée sur la combinaison des couches minces d’AlZr, CrN et CrCN déposées par PVD, et Al₂O₃, ZnO, TiO₂ et Al₂O₃-ZnO nanolaminées déposées par ALD. Pour mieux comprendre le rôle de chaque type de couche sur les propriétés physico-chimiques du revêtement hybride, la position et l’architecture de la couche ALD ainsi que l’influence de la variation de la période des bicouches de nanolaminées ont été analysées. Les résultats obtenus indiquent que la combinaison hybride des revêtements PVD et ALD présente une stratégie prometteuse pour améliorer la résistance à la corrosion par piqûres des aciers utilisés pour les applications maritimes.The PhD thesis aims to develop a new generation of duplex thin films performed by the combination of magnetron sputtering and atomic layer deposition techniques. The structure, morphology, mechanical behavior and electrochemical properties of different hybrid coatings architectures ALD/PVD, PVD/ALD and PVD/ALD/PVD were investigated. In this study, AlZr, CrN and CrCN PVD thin layers and Al₂O₃, ZnO, TiO₂ and Al₂O₃-ZnO nanolaminates ALD layers were combined in hybrid coatings. The position and the architecture of the ALD layer in the hybrid coatings as well as the influence of the variation of the nanolaminate bilayers period thickness were studied in order to further investigate their effect on the physico-chemical properties. The results revealed that the PVD and ALD hybrid coatings combination is a promising strategy to improve the pitting corrosion resistance of steels used in marine applications
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Advanced coatings for protection of metallic structures used in aqueous mediums
No full textInternational audienc
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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