1,721,051 research outputs found
Identification of two cracks in a simply supported beam from minimal frequency measurements
No full textThis paper presents a diagnostic technique for the identification of two cracks of equal severity in a simply supported beam under flexural vibrations. The crack is simulated by a rotational spring connecting the two adjacent segments of the beam. The analysis is based on an explicit expression of the frequency sensitivity to damage and the damaged system is considered as a perturbation of the virgin system. By measuring the changes of first three natural frequencies it is possible to study the inverse problem – identification of crack location and severity. The inverse problem is ill-posed, namely, even by leaving symmetrical positions aside, cracks with different severity in two sets of different locations can produce identical changes in first three natural frequencies. Numerical results show that if the natural frequencies used as data in identification are affected by errors relatively small with respect to the frequency-induced changes, then damage identification leads to satisfactory 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
Diagnostic impact of ultrasonography in abdominal diseases
No full textThe diagnostic accuracy of conventional radiography and ultrasound (US) in patients with acute or chronic abdominal pain was investigated by the authors in two prospective studies to assess the capabilities of the two imaging techniques. 262 patients (135 men and 127 women, age range: 25-83 years) were entered into the study within 8 months. The patients were divided into different groups according to clinical presentation (80 patients with acute and 182 with chronic pain) and to the referring physician (a hospital clinician for 127 patients and a general practitioner for 135 patients). For each technique the presence (positive result) or the absence (negative result) of abnormal imaging features related to clinical symptoms was recorded and the agreement of conventional radiography and US findings was assessed. Statistical analysis showed similar sensitivity of conventional radiography and US in the examination of acute hospitalized patients (54.3% positive results), chronic hospitali..
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