1,720,956 research outputs found
A linearized impact localization algorithm for the health monitoring of aerospace components
No full textLiterature presents a wide range of techniques and algorithms for the localization of impact source in isotropic structures. However, many of these methods involve either solving complex systems of nonlinear equations or a-priori training of the monitored structure. This is not only time consuming, but it requires high levels of computational effort that may often result in a poor estimation of the impact coordinates. This paper presents a novel structural health monitoring system for the impact localization on aluminium components. The proposed methodology, in contrast to current impact localization techniques, relies on an optimal sensor placement, which allows reducing the nonlinear system of equations to a linearized and simplified form. Two different Akaike Information Criterion (AIC) pickers are used to calculate the arrival times of the direct elastic waves originated by the impact source. To validate this methodology, experimental tests were carried out on aerospace components using four surface-bonded piezoelectric sensors. The results showed that this technique allows detecting and localizing the impact source with a high level of accuracy in any point of the structure
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
A Structural Health Monitoring Technique for the Reconstruction of Impact Forces in Aerospace Components
No full textDespite composite materials are widely used in aerospace components, they are characterized by low-impact resistance and, therefore, subject to barely visible damage. This can be due to a number of sources such as hailstones, tools drop, runaway debris and bird strikes. Hence, the real time knowledge of low-velocity impact magnitude on aeronautical composite structures is certainly one of the most demanded goal for structural health monitoring (SHM). This article proposes a novel ultrasonic SHM method for the reconstruction of the impact force history on composite components. The research work is based on an inverse problem applied to composite samples of unknown mechanical properties, whose global characteristics are obtained through the knowledge of the structural transfer function measured by a sparse array of surface-bonded piezoelectric sensors. Hierarchical interpolation methods are then used to reconstruct the magnitude of the impact force over the entire structural domain. Since the proposed methodology only requires the knowledge of the material response at discrete locations, it does overcome the limitation of current impact force reconstruction techniques, which require the use of either analytical models based on classical plate theory or numerical finite element simulations. This technique is experimentally validated on a composite panel with complex geometries by considering low-velocity impacts at multiple locations and different levels of magnitude
A hierarchical impact force reconstruction method for Aerospace composites
Full text linkThis research work presents a hierarchical method able to reconstruct the time history of the impact force on a composite wing stringer-skin panel by using the structural responses measured by a set of surface bonded ultrasonic transducers. Time reversal method was used to identify the impact location by the knowledge of structural responses recorded from a set of excitation points arbitrarily chosen on the plane of the structure. Radial basis function interpolation approach was then used to calculate the transfer function at the impact point and reconstruct the impact force history. Experimental results showed the high level of accuracy of the proposed impact force reconstruction method for a number of low-velocity impact sources and energies
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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