1,721,010 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
Condition based maintenance through electrical signature analysis : a case study
No full textIn modern industrial applications, because of the increasing requirements in term of quality and efficiency, the employment of an effective maintenance strategy is becoming crucial. As a consequence, the service activity is moving towards the development of diagnostics and prognostics techniques aiming to minimize the impact of the failures on the production. In previous papers two simple diagnostic indexes has been presented. It has been shown that under some hypothesis they are effective to detect rotor faults of inverter-fed asynchronous machines. In this work, the effect on indexes due to the accuracy of the current measurement chain has been investigated. This has led to the development of a low-cost diagnostic device employing. Hall-effect current transducers and a dsPIC microcontroller. Finally, it will be shown that the indexes computed by means of this economical hardware are close to that obtained employing a PC interfaced with a much more accurate current acquisition system
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
Order-Disorder Transformation in RuBr3 and MoBr3: A Two-Dimensional Ising Model
No full textABSTRACT: Several trihalides (Cl, Br, I) of elements of groups 4, 5, 6, and 8 of the periodic table, such as TiI3, show a crystal structure made by parallel infinite columns, running along c, of face-sharing octahedra [MX6]. The metals placed within the columns may interact with one of the nearest neighbors, so that long and short MM distances regularly alternate along the columns; two distinct conformations are possible for the columns, one with M-M pairs centered at z = 1/4, the other with M-M pairs centered at z = 3/4. Below a certain temperature the distribution of the two types of columns in the a,b plane is ordered, giving rise to an orthorhombic form, with space group Pnmm. Over this temperature a transition to a hexagonal form, with space group P63/mcm, is observed. We, through X-ray diffraction studies carried out at different temperatures, estimate this transition temperature for RuBr3 and MoBr3 crystals and show that the hexagonal form too consists of ordered columns, the..
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
Effects of the speed loop on the diagnosis of rotor faults in induction machines
No full textThe development of high-performance static converters and advanced control techniques has led to a widespread diffusion of asynchronous drive systems in industrial plants. One of the strong points of the induction machines is their reliability; however, an unexpected failure may still result in a considerable economic loss. This fact has stimulated a prolific research activity concerning the continuous monitoring of the wear status of induction machines. The knowledge of their condition allows implementing condition-based maintenance techniques, which have proven to be very effective in critical processes. In previous papers, the authors have focused their attention on the detection of broken rotor bars in inverter-fed induction machines. Two indexes have been defined: Both of them are simple methods to estimate the same fault indicator, namely, the ratio between the amplitude of the power oscillation and the average power draw of the drive system.
However, this fault indicator exhibits a noticeable dependence on the mechanical load as well as on the speed loop parameters.
In this paper, a deep investigation about these dependences is provided. The study suggests introducing a new fault indicator which is much less sensitive with respect to the torque developed by the motor. Furthermore, the analysis allows predicting how the speed loop affects the fault detection techniques. The results of the study and the effectiveness of the new fault indicator have been first verified bymeans of numerical simulations and then validated through an experimental activity
A VI based tool for inverter fed induction motor diagnostic
No full textNowadays Virtual Instruments (more briefly called VIs) are very useful tools both in research and industrial applications.
Their greatflexibility, re-configurability, reliability and ease of use allow an effective implementation of complex measurements architectures. In particular, the capability to manage long measurement processes without staff presence makes the VIs a powerful support for the development of diagnostic techniques which require a continuous monitoring ofthe system. In this paper a novel VI-based diagnostic monitoring technique which permits the identification of rotor faults in small inverter-fed induction motors will be presented
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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