1,720,956 research outputs found
Identification of Constitutive Model Parameters for Crashworthiness of Composite Structures Using Multiobjective Optimization
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An Inverse Approach to Identify the Constitutive Model Parameters for Crashworthiness Modelling of Composite Structures
No full textThis paper deals with an inverse technique, based on a multi-objective optimization, for the identification of model parameters defining damage and failure mechanisms in composite materials. The identification process is based on experimental tests of thin-walled cylinders in composite material and finite element analyses. The parameters identified are then used in finite element analysis to predict the dynamic response of subsequently modified energy absorbing structures manufactured for high performance vehicles. Overall assessment shows a good correlation between the experimental and numerical results. The numerical solutions are within 3% of experimental test data and yield noticeable structural performance improvement when evaluating the parameters under static loading
Composite Materials and Bird-Strike Analysis Using Explicit Finite Element Commercial Codes
No full textThe impact of a bird represents one of the most dangerous events for the safety of the modern aircraft. Statistics report that the consequences can be tragic, especially for the small airplanes. In this work, the impact of a bird against a nacelle inlet is analysed by the means of a proven Explicit Finite Element (FE) code, LSTC LS-Dyna. In particular, the dynamic characterisation of the composite materials used in manufacturing the external skin of the inlet was achieved by referring to the drop-tests carried Out using thin walled tubes of the same material. The data collected were used to define and tune the damage law of the numerical model. Once the material constitutive model was validated, an actual bird impact test was numerically analysed. In particular, two different bird models were considered: the customary Finite Element and the nodal masses bird model. The numerical results obtained were eventually qualitatively compared with experimental. In conclusion, some remarks on the results obtained are made
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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