1,720,958 research outputs found
Modal Density Influence on Modal Complexity Quantification in Dynamic Systems
Full text linkFrom an engineering point of view, it is important to recognize the proportional or non-proportional nature of the damping in dynamic systems. In the first case, the mode shapes are real, whereas in the second case they are complex. Typically, the entity of non-proportional damping is estimated through appropriate indices that measure the relative weight of the imaginary part of the mode shapes. A serious problem for the practical applicability of these indices is their dependence on the accuracy of the mode shapes identification. Above all, the modal density affects the identification quality by injecting fictitious complexity in the mode shapes regardless the identification technique used. It is the purpose of the paper to contribute to evaluate the effectiveness of the non-proportionality indices in the presence of modal density. The work is based on the comparison between theoretical (exact) solutions and experimental solutions. The results show that the error is almost constant up to a certain value of the modal density beyond which it markedly diverges. The results show also that the indices share the same trend even if differently scaled. The selection of the best index is also addressed. © 2017 The Authors. Published by Elsevier Ltd
Experimental Validation of Damage Indices Based on Complex Modes for Damage Detection in Vibrating Structures
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Effects of modal density in system identification using the Hilbert transform
No full textThe paper aims to review and deepen the effects of the modal density in the dynamical identification with the Complex Plane Representation (CPR) method that is based on the Hilbert transform of the motion response of mechanical systems. It is demonstrated that the strong accuracy in the identification of the modal parameters with the CPR method can be somewhat corrupted for high modal densities. Theoretical and numerical solutions are used to analyze the problem and validate the CPR results
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
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