1,721,020 research outputs found
Limits and Possible Enhancements of the Error Matrix Method for the Updating of Aeronautical Structures
No full textLocal characterization by cyclic indentation test of polymer matrix in 3D carbon fiber composites
No full textIn this work, local mechanical properties of PR520 epoxy resin matrix in 3D carbon fiber composite (in-situ) have been investigated through a cyclic indentation loading method and compared with that of the neat material. This loading enables to evaluate elastic as well as time dependent response of the material. The evolution of classical indentation and cyclic behaviour parameters with time is studied. The 3D carbon fiber composite used in this study contains a number of large resin pockets among fiber bundles (mesoscopic scale) with a characteristic dimension ranging from several hunred of micrometers to several millimeters. First of all, the homogeneity of polymer matrix was verified on the surface and in the volume of the composite. Then, a statistical analysis through Student t-test of in-situ parameters at the mesoscopic scale was performed with comparison to the neat material. The result showed that there is at least a 95% of probability that the neat and in-situ data sets belong to different populations. However this difference is quite small (between 1 and 2.5%) and almost constant with cycles
Application of the extra-modes method to the aeroelastic analysis of morphing wing structures
No full textWhen dealing with the design of morphing wings, conventional structural arrangements are commonly replaced by innovative solutions enabling shape changes through actively controlled elasticity or mechanical systems. In both cases, no simplified rules coming from consolidated experiences may be invoked to guarantee that a specific design will be characterized by stable and sustainable aeroelastic response to external loads expected in service.A rational approach for the aeroelastic analysis of the structural arrangements is therefore recommended since the earliest design stage so that the maturation of unflyable solutions is naturally avoided.The extra-modes method is herein detailed as a dramatically efficient tool to accomplish this paramount task. The morphing device is treated as a substructure and the aircraft (A/C) as the basic system on which the device is installed. Substructure's contribute to the aeroelastic response of the global system is expressed in terms of generalized parameters pertinent to additional and strategically defined modes capturing the substructure dynamics. After recalling the general formulation of the method, two case studies are presented in order to show its great potential to rapidly appreciate the aeroelastic behavior of a given design, irrespective of the maturity level of the design itself
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
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