1,720,964 research outputs found
Liquid Composite Molding for aeronautical structures
No full textLiquid Composite Molding (LCM) has gained popularity recently due to environmental concerns associated with open tool manufacturing. One subclass of LCM processes, that is gaining current research interest in aerospace field, is Resin Transfer Molding (RTM).The increasing number of papers and conferences about RTM shows that it is a very interesting technique in the aerospace, automotive and military industry. The reason why RTM is attracting a lot of attention is its potential of reducing manufacturing cost and creating an integrated part with complex geometry and high fiber volume fraction. Nevertheless, industry hesitancy to adopt this class of manufacturing process is due to unfamiliarity with the process, especially from a qualification point of view. This paper describes an application of procedure to improve reliability and predictability of RTM technology in order to decrease development cost and make the risk of quality defects during production as small as possible. Numerical and experimental results are reported. The helicopter transmission gearbox has been identified as a candidate for being redesigned using RTM technology
Manufacturing approach to realize a prototype of a helicopter transmission component by composite materials
No full textRe-design of a helicopter component transmission by composite material
No full textThe aim of this paper is to present an innovative application of composite materials by resin transfer moulding (RTM) technology for a helicopter component transmission traditionally made by metallic materials. This task requires a structural analysis performed simultaneously with an appropriate tooling design and the investigation of the material processability. In this work we present the structural optimization design for a component to be manufactured with braided preform, as well as a study of permeability and selection of resins. The purpose of the structural design was to minimize the weight of the structure through reduction of the total thickness with preservation or improvement of the mechanical performances. A simplified finite element model was adopted to obtain the distribution of thickness along the conical profile. In order to study the relationship between braided angle and permeability parallel to the mandrel axis, several experiments was conducted at different braided angles for some of thicknesses. This will be necessary to evaluate the best strategy of an injection scheme. The processability of a selected set of resins for aerospace RTM applications was carried out. The materials were chosen in order to guarantee the high mechanical, physical and thermal performance of the component in exam
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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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