1,721,003 research outputs found
Evaluation of Effective Strain and n-Value of ITER TF Conductor Samples
No full textThe acceptance tests of the Cable in Conduit Conductors for the Toroidal Field coils of the ITER magnet system are being performed at the SULTAN facility in Villigen, Switzerland. The main physical quantity measured in these tests is the current sharing temperature, Tcs . In Tcs measurements, the E-T characteristic curve of the conductor is traced. This curve is utilized here to evaluate the equivalent n-index and the effective strain of the superconducting Nb3Sn cable, under the simplifying assumptions of a uniform strain, current density and temperature distribution in the cable cross section. The variations of n-index and effective strain with mechanical cycling and their sensitivity to the applied transverse load and to the warm up-cooldown process are presented for various conductor samples tested recently
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
Error estimation in the Tcs measurement of TF conductors in the SULTAN facility
No full textThe main parameter measured in the tests of the TF conductors for the ITER machine is the current sharing temperature. In the voltmetric assessment of Tcs, the voltages are measured on the conductor jacket, due to the technical difficulties to introduce voltage taps inside the stainless steel conduit. The average voltages measured on the jacket do not exactly correspond to those that arise along the single strands, as shown by the presence of early voltages arising during the current ramp up, when the cable is still in the superconducting phase. It is therefore not trivial to evaluate the difference between the cable and jacket voltages, that gives rise to an experimental error in the measurement of Tcs. This paper reports the results of a vast simulation campaign performed with a detailed electromagnetic model of the Cable in Conduit Conductor, in which the origin and the extent of these differences have been investigated, giving an estimate for the experimental error. The impact on measurements of other sources of error such as the signal/noise ratio and the error in the temperature measurements is also reported
Non linear analysis of the cable layout influence on the stiffness of a ITER full size conductor
No full textSensitivity Analysis of Tcs Measurement on ITER TF Conductors
No full textThe measurement of current sharing temperature of Cable in Conduit Conductors is the main test for the acceptance of
superconducting cables for the ITER Project. This temperature is
defined as the one at which the average electric field along the cable reaches a critical value of 10 microV/m. Due to the complexity of the measurement, the evaluation of Tcs from the experimental results is not straightforward. Different techniques of elaboration of the raw experimental data can result in rather different estimations of Tcs.
The aim of this work is to elaborate a standardized procedure of
data treatment to be applied to all measurements. To this purpose,
the assessment of the impact of the different measurement
methodologies and data treatment techniques applied in the procedure is very important. A sensitivity analysis is therefore presented, to evaluate the influence on the final evaluation of of
the main parameters and methodologies involved in the proposed
procedure
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