1,720,966 research outputs found
Stress-based formulation for non-linear analysis of curved beams
No full textThe linear and non-linear analysis of curved beams is a very classical but still very discussed topic in literature. The most commonly used approach is the displacement approach, which is affected, as it is well known by locking phenomena.
A viable alternative to overcome the problem of locking encountered is represented by equilibrium formulation in static linear analysis and mixed formulations in dynamic and non-linear analysis. In particular, in non linear analysis of beams formulations based on a Hellinger-Reissner variational principle or modified Hu Washizu principle have been proposed in literature.
In this paper a valid alternative is proposed for the non-linear analysis of an arbitrarily curved, extensible, shear flexible, elastic planar beam. The proposed formulation is based on a new variational principle expressed in terms of stress components. In particular, the unknowns are represented by the bending moment and by a variable from which the shear and the axial force can be expressed and by the generalized forces at the extremities of the bar. The Euler-Lagrange equations of this principle are the elasto-kinematic relations related to the curvature and the moment equilibrium equation. The effectiveness of the approach is illustrated through numerical examples. A comparison in terms of displacements and stress with the other formulations available in literature ends the paper
Una formulazione mista agli sforzi e una modellazione geometrica nella dinamica lineare delle travi curve
No full textLa dinamica lineare delle travi curve è stata trattata facendo uso di una formulazione mista agli sforzi. Le azioni interne sono stata divise in tre parti: una in equilibrio con i carichi esterni, una autoequilibrata ed, infine, una in equilibrio con le forze di inerzia. Quest’ultima è stata ottenuta integrando un campo di spostamenti tale che il numero dei modi deformativi risulti pari al numero dei modi tensionali. Si è sviluppata una particolare descrizione geometria che si avvale delle sole coordinate dei punti interni che fungono da interelemento, e delle coordinate e delle tangenti nei punti di estremità. Detta rappresentazione è impostata su funzioni cubiche hermitiane modificate, modellate attraverso due parametri che aggiungono flessibilità alla descrizione classica. I parametri sono poi calcolati minimizzando la curvatura di tutto l’arco. Il metodo è stato testato con un esempio tratto dalla letteratura in cui vi è una soluzione esatta di riferimento
A mixed stress model for linear elastodynamics of arbitrarily curved beams
No full textThis work presents a mixed stress finite element for linear elastodynamics of arbitrarily curved beams based on a modified Hellinger-Reissner functional. A rational approach to choose the stress approximation is proposed. In particular, the self-equilibrated stress is augmented by some stress modes obtained from the lower-order displacement approximation using the equilibrium equations, in such a way that the total number of stress modes is equal to the number of strain modes. The rationale is to preserve all the interactions among the stresses, proper of a curved structure without compromising the flexibility of the element. An arbitrarily curved geometry is described using a parametric Hermitian interpolation scheme tuned by minimizing the initial curvature of the arch. The effectiveness of the present approach is numerically demonstrated
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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