1,720,972 research outputs found
Effects of the Nb3Sn Wire Cross Section Configuration on the Thermal Stability Performance
No full textThe thermal and electrical conductivities of the normal matrix of LTS wires have a remarkable influence on the wire stability. In particular, in Nb3Sn wires, a bronze matrix in the region of the superconducting filaments may act as a thermal and electrical barrier between the filaments and the copper matrix. This phenomenon is analyzed here through a numerical model accounting for these thermal and electrical transverse resistances. The model is applied to a parametric analysis of the effect of the main properties of the wire matrix on the quench energy
and velocity. A 2D analysis of the wire cross section is applied to
investigate how a configuration change could improve the wire
stability
Comparing Thermal Stability of NbTi and NbSn Wires
No full textThe investigation of quenching in low temperature superconducting wires is of great relevance for a proper design of superconductive cables and magnets. This paper reports the experimental results of a vast measurement campaign of quench induced by laser pulses on NbTi and NbSn wires in pool boiling Helium I. A comparison of the quench behavior of two typical NbTi and NbSn wires is shown from different standpoints. Different qualitative behaviors of the voltage traces recorded during quenches and recoveries on NbTi and NbSn wires are reported and analyzed. It is shown that the NbSn wire exhibits a quench or no-quench behavior, whereas quenches and recoveries are exhibited by the NbTi wire. The two wires are also compared considering the behaviors of the two main parameters describing quench, i.e. quench energies and quench velocities, with respect to operation current and pulse duration and magnetic field. It is shown that the NbSn wire exhibits a ‘kink’ of the quench energy vs current curve that makes the quench energy of NbSn lower than that of NbTi at some intermediate current levels. Both the qualitative differences of the voltage traces and the different behaviors of quench energies and velocities are interpreted through a coupled electromagnetic- thermal model, with special emphasis on the detailed description of heat exchange with liquid helium
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
Stability of Nb3Sn superconducting wires: the role of the normal matrix
No full textThe stability of ���� superconducting wires is
a crucial issue in the design and operation of reliable superconducting
magnets. High current density magnets, such as those
presently developed for future accelerator projects, may be subject
to premature quenches due to local releases of energy. In
this paper we study the results of stability experiments that have
been performed using a single mode Diode Laser with an optical
fiber to illuminate the superconducting strand surface and trigger
fast quenches. The development and propagation of laser-induced
quenches have been measured on Nb3Sn strands in LHe bath by
means of three voltage taps. This paper deals with the numerical
analysis of the experimental results. A coupled electric and
thermal model has been developed to study the quench propagation.
The experimental evidence of a different qualitative behavior
of the voltage traces recorded on ���� strands with respect to
NbTi strands is explained by means of a more detailed physical
model of ���� strands, that takes into account electrical and
thermal transverse resistances
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
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