1,721,009 research outputs found
Processing of Acousto-Ultrasonic Data for analysis of temperature parameters and damage detection in CFRP Structures
No full textThe aim of this work is to study the damage detection capability by means of Lamb wave propagation
in a CFRP omega-stringer stiffened panel in presence of changing environmental conditions.
Temperature influence in Lamb wave propagation as well as damage detection methods for changing
environmental conditions have already been studied on other stiffened structures, although for
different materials and geometries.
For the actuation and sensing a network of bonded piezoceramic transducer has been used and the
temperature test has been performed introducing the structure in an oven with temperatures going
from 40°C until 80°C. A total of 13 delaminations or debondings have been induced in three zones of
the structure geometry with a mobile impactor. After the impact introduction the temperature test
has been repeated in order to compare the data acquired before and after the impact in the same
environmental conditions.
The temperature test has been used to first identify by experimental means the variations in Lamb
wave propagation through the given CFRP-stiffened panel caused by temperature. Afterwards, signal
processing permits to determinate the adequate modes, frequencies and parameters in order to
detect damage. Dispersion curves assisted by a scatter study prove that A0 mode is the most suited
mode for SHM means since it is the most sensitive to alterations in the structure. The last part of the
study is finds several parameters capable to detect damage in spite of temperature variations.Outgoin
Processing of Acousto-Ultrasonic Data for analysis of temperature parameters and damage detection in CFRP Structures
No full textThe aim of this work is to study the damage detection capability by means of Lamb wave propagation
in a CFRP omega-stringer stiffened panel in presence of changing environmental conditions.
Temperature influence in Lamb wave propagation as well as damage detection methods for changing
environmental conditions have already been studied on other stiffened structures, although for
different materials and geometries.
For the actuation and sensing a network of bonded piezoceramic transducer has been used and the
temperature test has been performed introducing the structure in an oven with temperatures going
from 40°C until 80°C. A total of 13 delaminations or debondings have been induced in three zones of
the structure geometry with a mobile impactor. After the impact introduction the temperature test
has been repeated in order to compare the data acquired before and after the impact in the same
environmental conditions.
The temperature test has been used to first identify by experimental means the variations in Lamb
wave propagation through the given CFRP-stiffened panel caused by temperature. Afterwards, signal
processing permits to determinate the adequate modes, frequencies and parameters in order to
detect damage. Dispersion curves assisted by a scatter study prove that A0 mode is the most suited
mode for SHM means since it is the most sensitive to alterations in the structure. The last part of the
study is finds several parameters capable to detect damage in spite of temperature variations.Outgoin
Processing of Acousto-Ultrasonic Data for analysis of temperature parameters and damage detection in CFRP Structures
No full textThe aim of this work is to study the damage detection capability by means of Lamb wave propagation
in a CFRP omega-stringer stiffened panel in presence of changing environmental conditions.
Temperature influence in Lamb wave propagation as well as damage detection methods for changing
environmental conditions have already been studied on other stiffened structures, although for
different materials and geometries.
For the actuation and sensing a network of bonded piezoceramic transducer has been used and the
temperature test has been performed introducing the structure in an oven with temperatures going
from 40°C until 80°C. A total of 13 delaminations or debondings have been induced in three zones of
the structure geometry with a mobile impactor. After the impact introduction the temperature test
has been repeated in order to compare the data acquired before and after the impact in the same
environmental conditions.
The temperature test has been used to first identify by experimental means the variations in Lamb
wave propagation through the given CFRP-stiffened panel caused by temperature. Afterwards, signal
processing permits to determinate the adequate modes, frequencies and parameters in order to
detect damage. Dispersion curves assisted by a scatter study prove that A0 mode is the most suited
mode for SHM means since it is the most sensitive to alterations in the structure. The last part of the
study is finds several parameters capable to detect damage in spite of temperature variations.Outgoin
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
Damage Identification in Composite Panels Using Acousto-Ultrasonic Waves
No full textA methodology for the identification of barely visible impact damage using acousto-ultrasonic waves on a typical aircraft composite structure is implemented. Delaminations and debondings have been introduced in two stiffened panels by means of impact loads
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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