1,720,963 research outputs found
Impact damage detection in composite plates using deflectometry and the Virtual Fields Method
No full textThis paper presents a new method for detecting damage in layered composite materials using a simple measurement technique, deflectometry. The aim is to locate the damage in a specimen and provide a “signature” from the measured surface slopes. Firstly, this method is applied to plate specimens using numerical and experimental data. Secondly, damage indicator based on a new application of the virtual fields method to compute local apparent gaps in equilibrium is presented and used to process the measurements on plates. It is shown that the damage indicator is very sensitive, allowing detection of damage that is difficult to identify directly from the strain maps
Time-resolved full-field imaging of ultrasonic Lamb waves using deflectometry
No full textThis pioneering experimental work is a proof of concept in which ultrasonic flexural waves have been imaged in a spatially and temporally resolved manner. Thin vibrating plates made of mirror glass and carbon/epoxy composite have been used in the experiments. Results obtained via a standard approach (scanning laser Doppler vibrometry) and the novel methodology based on deflectometry have been compared with a multi-physics finite element simulation. There is a very good correlation between the two experimental techniques. The numerical model provides insight into the experiments, but differs in its detailed structure due to uncertainties over material properties. The extreme slope resolution of deflectometry allows the measurement of peak-to-peak deflections of a few tens of nanometres in one shot. The use of an ultra-high speed camera allows for both space and time resolved measurements of Lamb waves which, to the best knowledge of the authors, has never been reported before. The limitations of the technique arise from the need for a flat specularly reflective surface. However, coating is possible for non-reflective materials and extension to moderately curved surfaces is possible in the future
Mechanical characterization of open cell aluminium foams reinforced by nickel electro-deposition
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Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
No full text“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
No full textWe 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
Low cost infrared thermography for automated crack monitoring in fatigue testing
No full textThe potential of using infrared thermography in the assessment of crack-tip parameters is described. The use of microbolometers is studied specifically to establish their suitability for use in thermoelastic stress analysis (TSA) for establishing the crack-tip parameters and for automatically monitoring crack growth using temperature measurement. To compare the behaviour of the two types of infrared cameras a camera model is devised, which is used to predict the thermoelastic response. A new automatic crack growth monitoring approach is developed based on the temperature measurement from the raw thermal data collected using the microbolometer. The thermoelastic response model and the crack monitoring procedure are demonstrated on 316 L stainless steel single edge notch tension (SENT) specimens. Cracks were established in the specimens, grown and monitored using both types of infrared detector. The procedure is validated using measurements from the photon detector and it is shown that accurate stress intensity factors (SIFs) can be obtained from growing cracks using directly the live readings from the microbolometer. The procedure provides a new means for non-contact measurements in fatigue testing, establishing crack growth rate and the SIFs with the potential for actuator control.</p
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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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