1,720,958 research outputs found
Multi-scale damage analysis of composite structures
No full textThe number of applications of composite materials in different industries including aerospace, marine, automotive and civil are increasing due to the several advantages they provide. However, there are still some applications that composite materials are not used because of the lack of deep knowledge and fast methods in composite modelling. Therefore deeper understanding of damage behaviour and faster methodologies are required in order to increase the usage of composites. The aim of this research is to take the advantage of the multi scale nature of the material in order to define structural behaviour of composites. The structure can be considered in three scales: macro-level, meso-level and micro-level. Composite materials gain most of the advantages becoming heterogeneous material, however this feature have significant effects on the behaviour of the macroscopic level. An accurate and fast approach at macro level is required to estimate the structural response and effect of micro level mechanisms should be investigated to define this macro level response. In this thesis, the studies are conducted in two level: Macro and Micro. A composite stiffened plate is modelled with finite element approach at macro level. The model is generated with geometrically non-linear and materially linear approximations. The results show good agreement with experiments in literature. But, the accuracy of the modelling is improved by including material non-linearity. Therefore, a progressive damage model is developed and applied to a composite plate at meso-level. The results presented the requirement of damage modelling. In order to have an accurate way of predicting the damage behaviour of structures, micro-level mechanisms are modelled. An RVE model is generated in order to model micro level responses of composite materials. The model provided good approximations for material properties compared to experimental estimations with numerical modelling approach and seem promising to model damage behaviour of composites. Despite the increased usage composites, manufacturing variability is still not well understood. To increase structural safety it will be important to understand the effect of inherent variations on the failure, how do variations from different manufacturing processes effect the structural reliability? Increasingly material variations are being investigated, with an assumption that these variations are more important than topological defects. In this study, the impact of material and topological variations on structural integrity are compared via a reliability assessment. By using direct monte-carlo simulations, the reliability of top-hat stiffened plates is explored. Halpin-Tsai and Representative Volume Elements are utilised to characterise the material and an empirically adapted Navier grillage method is employed for structural analysis. The reliability of structures with only material variations (up to 20%) exhibited significant differences when equivalent variations are applied for both levels. Material variations have an order of magnitude higher impact on structural reliability of stiffened plates than topological variations (up to 20%), meaning that the focus on materials is justified but that topological defects should be further investigated
Modelling the different mechanical response and increased stresses exhibited by structures made from natural fibre composites
No full textNatural fibres exhibit improved sustainability and similar mechanical properties to E-glass. However, for laminates there is a larger difference in properties and limited assessments of structural components. An analytical method for grillages is developed which is generally shown to predict the stress to within 5% of an FEA model. The simulations demonstrate a change in structural response between flax and carbon, with flax demonstrating higher stresses than expected for the lower Young’s modulus for the same topology. Flax is shown to be more sensitive to transverse Young’s modulus than standard composites and a better characterisation of this property is required
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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