1,720,972 research outputs found

    Flow induced alignment of fibres in HPFRCC slabs: non-destructive magnetic survey and correlation with failure modes

    No full text
    Structural applications with Ultra High Performance Fibre Reinforced Concretes (UHPFRC) have been emerging worldwide thanks to the outstanding tensile strength and ductility of this category of advanced cement based materials. From a design point of view, a critical aspect is to guarantee the ductility of the structural response associated to local material non-brittleness, which strongly depends on the fibre dispersion and orientation. This work aims at considering the effect of fibre orientation on the behaviour of UHPFRC slab for composite bridges. Several square slabs made of UHPFRC were cast by changing the concrete flow direction and the position of internal cold joints, in order to document the structural consequences of defects in the casting process.. The slabs were tested under biaxial bending under hyperstatic conditions. For four of these slabs, featuring different casting methods in order to induce different, even “defective” dispersion of fibres, a non-destructive magnetic method was employed to provide a complete survey of local dispersion and orientation of the fibres. The damage process, with emphasis on the micro-crack formation and the crack opening, was measured by 3D digital image correlation. The on-going cracking and failure modes were hence analysed in view of the guessed dispersion and orientation of fibres, highlighting the important effect of fibre orientation on the ductility of UHPFRC slabs and the ability of combining magnetic methods and DIC analyses to capture those effects

    Going Beyond Counting First Authors in Author Co-citation Analysis

    Full text link
    The 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 link
    We 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 link
    We 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
    corecore