1,720,958 research outputs found
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
Quasi-trivial solutions for uncoupled, homogeneous and quasi-homogeneous laminates with high number of plies
No full textQuasi-trivial (QT) sequences are a class of lamination stacks for which, in the framework of Classical Laminate Theory (CLT), the properties of uncoupling and/or homogeneity are verified in a closed-form solution [1]. These sequences have received great attention from the scientific community as they have proved to be an extremely powerful tool for the design and optimization of composite laminates. Nevertheless, two main reasons limit their adoption: first, to find QT sequences, a complex algorithm is required; second, calculations become computationally intensive for long QT sequences, thus limiting the maximum number of plies attainable. This constrains the use of QT stacks to applications involving only thin laminates. In order to exploit QT stacks for thick laminates new tools are proposed. Firstly, a new and more efficient algorithm for finding QT stacking sequences is developed and an original procedure is devised to effectively code it. The proposed algorithm finds a greater number of QT solutions, with respect to those given in [1]. Additionally, analytical relationships to obtain new QT sequences by superposition of known QT sequences are presented in [2]. Thanks to this new class of closed-form solutions, laminates can be designed using QT stacking sequences without limitations on the maximum number of plies. The results presented in this work open new possibilities for the design and optimisation of thick laminates. In addition, laminates with special requirements may be designed by superposition of QT stacks, thus reaching specific design goals that cannot otherwise be met
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 novel bio-inspired microstructure for improved compressive performance of multidirectional CFRP laminates
No full textIn this work, we design, manufacture, test and discuss the first bio-inspired microstructural concept to enhance longitudinal compressive performance of multidirectional (MD) Carbon Fibre Reinforced Polymer (CFRP) laminates. To do so, we take inspiration from biologically occurring layered materials; one remarkable example being the anchoring spicula of the deep-sea glass sponge Monoraphis chuni. We designed numerically various concepts and then devised a strategy to reproduce, in a MD CFRP laminate, the characteristic alternation of stiff and soft regions observed in this material, followed by a bespoke procedure to manufacture the laminate. We evaluated their performances by means of small-scale notched compression tests and direct comparison with an industrially relevant baseline laminate. Our results show that the proposed concept led to a statistically significant increase in the failure load and in the average ligament specific stress at failure. Furthermore, the designed microstructure showed potential to delay damage initiation from a stress concentration and to arrest damage propagation. We conclude that the presented microstructural concept is potentially of great value for the design of lightweight structures undergoing compression loading
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
Co-infused and secondary bonded composite stiffened panels in compression: Numerical and experimental strength assessment combined with NDI and guided waves based SHM
No full textAdhesive junctions or co-infusion of skin and stiffeners represent efficient manufacturing processes for aircrafts composites stiffened panels leading to weight saving, although they have not been widely adopted yet due to certification issues and the lack of well-established design tools and procedures. Airworthiness requirements for composite structures pose major challenges to the certification of adhesively bonded or co-infused stiffened structures. FAA Advisory Circular 20-107B prescribes the methods for substantiating the limit load capacity of any bonded stiffener, the failure of which would result in catastrophic loss of the airplane. Today, composites primary structures that work mostly under compressive loads are designed following the no-buckling criteria up to Ultimate Load. Such a design approach leads to stiffer and heavier structures if compared to letting the compressed skins work in post-buckling until failure. In order to exploit the full structural potentiality of this type of structures under compressive loads new design approaches, mostly based on Finite Element Modelling, have to be developed and validated with experimental results to correctly predict the nonlinear mechanisms of load absorption beyond skin buckling onset. Furthermore state-of-the art Non-Destructive-Techniques and Structural Health Monitoring Systems can be employed for a continuous monitoring of the joints health status. In this context, the joining technique of the stringers to the skin has a particular importance; indeed, although different joining processes barely influence the linear behavior of a stiffened plate until its first instability load, they are responsible for relevant differences in the ultimate failure load. This paper presents numerical and experimental activities carried out to study the behavior of compressed stiffened plates obtained by different manufacturing processes as well as monitoring techniques of the health status of the panels by classical NDT and guided waves based SHM systems. The numerical problem has been modelled with approaches of increasing complexity, from “classical” FE models to predict the first buckling load, to post-buckling analyses up to more refined techniques including the behavior of the skin-stiffener interface
Experimental assessment of Fully-Uncoupled Multi-Directional specimens for mode I delamination tests
No full textThis paper proposes an experimental study whose goal is to validate the concept of Fully-Uncoupled Multi-Directional (FUMD) specimens for delamination tests. In order to reduce the likelihood of delamination jump, a glass/epoxy UD-fabric composite was used to fabricate double cantilever beam specimens. Mode I tests were performed with standard UD specimens and with FUMD specimens having the following delamination interfaces: 0 °//0 °, 0°// 15°, 0 °//30 °, 0 °//45 ° and −45 °//45 °. Delamination fronts after the tests were observed by means of ultrasonic C-scans. By comparison with the UD specimens, it is shown that FUMD sequences are able to promote a fairly symmetric and flat delamination front. Analysis of the rotations of such specimens during the test confirms that they do exhibit an uncoupled mechanical behaviour. Critical energy release rate is found to be dependent on interface plies mismatch angle, but not on global stiffness of the specimens
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