1,720,974 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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Initiatie van vermoeiingsscheuren en facetvorming in Ti-6Al-4V draden
No full textIn Ti-6Al-4V, fatigue cracks can nucleate internally instead of at the surface. Internal or subsurface cracks in titanium alloys are found to initiate at faceted features, which can be seen on the fracture surface after failure. These facets are fractured primary α (hcp) grains, which have broken in a very planar manner. The main purpose of this work is to study internal fracture in drawn Ti-6Al-4V wires, which has not been done before, since all published studies use forged or rolled samples. Fatigue tests with load ratio R=0.1 and a frequency of 60 Hz have been performed on wires with average α grain sizes of approximately 1, 2, 5 and 10 µm. In total, 50 samples were successfully tested. Four samples broke due to an internally initiated crack after testing at a maximum stress of 750 MPa: three samples with average alpha grain size 5 μm, which failed after 2.6 x 10^7, 5.7 x 10^7 and 9.6 x 10^7 cycles, and one sample with average alpha grain size 10 μm, which failed after 7.6 x 10^6 cycles. In general, an increase in grain size resulted in lower fatigue lives. In the four samples with internal crack initiation, a cluster of facets was observed at the initiation site on the fracture surface. The projected area size of the facet-containing area was not related to the fatigue life, and the estimated threshold stress intensity factor range was between 6 and 8 MPa√m. The actual surface area, taking into account the roughness, was correlated to the fatigue life. The facets were not smooth, but showed some nano-roughness with linear markings. As a result of the crystallographic texture, the facets were highly inclined, at angles mostly between 50° and 70°. Nearly all facets were parallel to a prismatic lattice plane. The linear markings on these facets were parallel to the direction of the prismatic slip system, which means that facet formation most likely occurred by a prismatic slip band mechanism. One anomalous facet was observed in the sample with an average grain size of 10 µm. This facet coincided with a near-basal plane, and displayed a fan-shaped pattern instead of linear markings, which indicates that a cleavage mechanism took place. These observations suggest that both a slip-based and a cleavage-based mechanism are possible, depending on the grain size, local texture and possibly other parameters. A local comparison of Taylor factors showed that the Taylor factor of each faceted grain had a tendency towards being higher than the Taylor factors of its corresponding neighbouring grains. It is suggested that the Taylor factor may be used to distinguish between plastically hard and soft grain orientations, and therefore could be capable of explaining the stress distribution between grains, which is the root cause for facet formation. Fracture surface cross-sections revealed secondary facets, which in some cases extended through more than one grain. Short crack growth through a grain boundary occurred when two compatible slip systems were present in these grains. This compatibility could be expressed by calculating misalignment factors. Additionally, a limited number of dwell fatigue tests have been performed, with a hold time of 30 or 120 s at maximum load. Introducing a hold time at maximum load drastically reduced the amount of cycles to failure by two to three orders of magnitude compared to regular fatigue tests, and promoted surface crack initiation. This was caused by strain accumulation due to cold creep, which occurred during each maximum load hold. A recovery process took place during each minimum load hold, which caused an increased initial strain rate during each following maximum load hold.status: Publishe
The influence of the alpha grain size on internal fatigue crack initiation in drawn Ti-6Al-4V wires
No full textAbstractIn the very high cycle fatigue regime, the location of crack initiation in titanium alloys is known to shift from the surface towards the bulk of the material. This internal fatigue crack initiation results in faceted features on the fracture surface. These facets are in fact alpha grains that have been broken in a planar manner. Typically, a cluster of many facets is observed either just below the surface or deeper inside the bulk. In this study, uniaxial tension-tension fatigue tests are performed on Ti-6Al-4V wires which have been subjected to different heat treatments in order to vary the alpha grain size. Four different microstructures are obtained, with average alpha grain sizes of approximately 1, 2, 5 and 10 µm. The fatigue life is found to decrease with increasing grain size. Electrochemical polishing of the wires prior to fatigue testing is applied in order to promote internal crack initiation at higher stresses and consequently shorter testing durations. Four samples broke due to an internal crack: three samples with average alpha grain size 5 µm, which failed after 2.6 x 107, 5.7 x 107 and 9.6 x 107 cycles, and one sample with average alpha grain size 10 µm, which failed after only 7.6 x 106 cycles. The threshold stress intensity factor range, which is calculated from the size of the facet-containing area, is between 5 and 6 MPa.m1/2 for all four samples. Fractographic examination of the facets reveals that they are not smooth, but show roughness at the nanoscale. This roughness has a linear appearance for nearly all facets, except for one anomalous facet in the sample with the largest grain size, which shows a fan-shaped pattern. From electron backscatter diffraction measurements on cross-sections of the fracture surfaces obtained by focused ion beam milling, it is also found that nearly all the facets coincide with a prismatic plane, and the linear markings are parallel to the prismatic slip direction. Only the anomalous facet has a near-basal orientation. These observations suggest the possibility that facets are formed by either a slip-based mechanism or a cleavage-based mechanism, and that the alpha grain size is one of the parameters that controls which mechanism occurs
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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