1,721,207 research outputs found
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
Laser as an innovative tool for laminates repair
No full textThe challenges during the mechanical machining of Fiber Reinforced Plastics like
delamination, fiber tearing and rapid tool wear are well known, nevertheless, the
relevance of CFRPs in the industrial community is still increasing. Due to this fact the
development of new methods for machining and treatment is needed to close this
technological gap. A promising cost-saving and time-saving technique is represented
by the laser ablation of bulk material. This paper presents the implementation of a
laser system for the treatment of laminates whose mechanical properties have been
compromised by external damage during the operation. The purpose of this
approach is to remove damaged material to provide a cavity for refilling with repair
plies. Our results show that it is possible to achieve a reliable and automatable
process with an even removal rate to perform arbitrary repair cavity geometries. The
laser machining set-up, equipped with a pulsed UV-laser and a galvo-scanning head,
avoids heat affected zones (HAZ) and detachment of fibers from the thermoplastic
matrix (here: PEEK). The laser-ablated and repaired laminates were then used to
prepare standard specimens to be tested according to DIN 65148. Detailed results of
the DIN 65148 of the repaired structure are presented in the final part of the paper
Laser-based repair for carbon fiber reinforced composites
No full textRecent progress in laser system technology enables innovative techniques for the machining of CFRPs. A representative application is the layer-by-layer removal of damaged composite material to provide a cavity for refilling with repair plies. Results show that it is possible to achieve a reliable and automatable removal rate to perform arbitrary repair cavity geometries, obtaining a relevant time reduction with respect to the conventional manual grinding process. The combination of modern UV-laser sources with a scanning technology enables scanning speeds of up to 4.0 m s-1, and suppresses heat affected zones and detachment of fibers from the polymer matrix. The interlaminar shear strength of repaired laminates and reference specimens have been measured and evaluated according to DIN 65148, and the results are reported here
Laser-based repair of carbon fiber reinforced plastics
Full text linkThe recent progress in laser system technology enables innovative techniques for machining of carbon fiber reinforced plastics (CFRPs). A representative application is the layer-by-layer removal of damaged composite material to provide a cavity for refilling with repair plies. Results show that it is possible to achieve a reliable and automatable removal rate to perform arbitrary repair cavity geometries, obtaining a relevant time-reduction with respect to the conventional manual grinding process. The combination of modern UV-laser sources with a scanning technology enabling deflection speeds up to 2 m/s, suppresses heat affected zones (HAZs) and detachment of fibers from the polymer matrix. A method for the selective removal of surface matrix without damaging the fibers beneath is also presented
Chapter 12: Laser-based repair for carbon fiber reinforced composites.
No full textThe recent progress in laser system technology enables innovative techniques for machining of CFRPs. A representative application is the layer by layer removal of damaged composite material to provide a cavity for refilling with repair plies. Results show that it is possible to achieve a reliable and automatable removal rate to perform arbitrary repair cavity geometries, obtaining a relevant time-reduction respect to the conventional manual grinding process. The combination of modern UV-laser sources with a scanning technology enabling deflection speeds up to 4,0m/s, suppresses heat affected zones (HAZ) and detachment of fibers from the polymer matrix. Finally, according to DIN 65148, the interlaminar shear strength of repaired laminates and reference specimens were measured and evaluated
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
- …
