1,721,405 research outputs found
A FRACTURE MECHANICS-BASED MICROMECHANICAL MODEL FOR FATIGUE BEHAVIOUR OF FIBRE-REINFORCED COMPOSITES
No full textComposite materials are widely used in engineering
applications due to their remarkable mechanical
properties, such as significant strength, elastic modulus,
fatigue strength and fatigue damage tolerance. They
consist of two or more constituents combined at a
macroscopic level, and their classification is usually based
on the kind of matrix material (polymers, metals,
ceramics) and reinforcing phase (fibres, particles, flakes).
Among them, fibre-reinforced composites (FRCs) are
often used for their fabrication simplicity and affordable
costs. Typical damage phenomena leading to a significant
loss of the mechanical performance are: matrix cracking,
fibre-matrix debonding, fibre breaking, fibre instabilities.
In particular, matrix cracking and fibre-matrix debonding
are crucial for the proper assessment of in-service safety
and the optimal design of such a class of materials.
In this work, a micro-mechanical model for FRCs
under cyclic loading is presented together with a
numerical example which shows the effect of fibre
orientations on fatigue behaviour
FE modelling of buckling and postbuckling of pultruded FRP built-up columns with closely spaced profiles
No full textPrevious research papers on this subject do not raise the issue of a systematic approach to the design of PFRP built-up members, which should consider: various basic profiles (C- and L-shaped, etcetera); different types of connection between basic profiles (battens and or lacings, connected by bolting and/or bonding, etcetera); changes in geometric characteristics (member total length, spacing of the battens, etcetera); and various types of loading.
In this context, the present paper has as the main objective to develop a design equation for built-up columns made of pultruded material. The proposed design equation is based on a preliminary series of parametric analyses of columns comprised of two closely spaced C-shaped profiles
Fracture toughness of hybrid fibre reinforced concrete
No full textIn the present paper, the fracture behaviour of
HFRC (hybrid fibre reinforced concrete)
specimens is examined, with copper and
polypropylene fibrillated fibres being randomly
distributed in concrete. The modified twoparameter
model is employed to compute the
critical stress intensity factor (fracture
toughness), taking into account the possible
kinked crack occurring during the stable crack
propagation
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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