1,721,047 research outputs found
On extended models of plates based on linear strain gradient elasticity
No full text© 2018 Taylor & Francis Group, London. Here we discuss the possible ways of derivation of two-dimensional (2D) plate equations starting from the three-dimensional (3D) linear strain-gradient elasticity. Among various approaches we consider the direct approach, the through-the-thickness integration procedure and variational approaches based on minimization of total energy functional and other variational principles. We show that the non-classic boundary conditions of the 3D strain gradient elasticity and the reduction method may generally lead to different plate model, in general. As a result, the mechanics of plates based on strain gradient elasticity is broader than the classic theory
A note on design of fiber-nets for maximum stiffness
No full textFor a specific fiber-net, the design variables are relative fiber density and fiber orientations. With a given amount of fibers, our objective is to maximize the stiffness (minimize the compliance) for a continuum subjected to a given load situation. Analytical optimality criteria are derived, and numerical optimization procedures are presented. Applications to a wedge problem from the literature, Royer-Carfagni (2000), and to a skew plate problem are shown, and the study includes the influence of a basic material to be reinforced. The procedure described can be combined with localized optimal design for density, orientation, and shape, "pointwise" or for design regions
A model for calculation of stress corrosion crack growth
No full textAs much as 25% of all accidents in process industry reported to the Swedish Plant Inspectorate are caused by stress corrosion crack growth. The situation is believed to be similar in the all industrialised countries. It contributes to the severity of the accidents that they often occurs unexpectedly and at loads that may be far below what normally causes crack growth Experts in the fields of metallurgy, corrosion have treated stress corrosion using mechanical models based on elastic or elastic plastic stress fields where the crack tip is treated as a point. In view of the near tip load distribution this leads to paradoxic results. In the present model corrosion is forming the geometry of the crack tip and is thus itself creating the conditions for strain concentration. We incorporate an interaction between electro-chemical processes and the deformation of the crack tip region in a fracture mechanical theory. The model is based on material dissolution simply being proportional to the surface stretch. No crack growth criteria is used. Computation of the mechanical state is based on a finite element formulation for large strains. The formation of a crack from a surface depression via a pit is studied. Low frequency cyclic load is considered. At the end of a load cycle a metal oxide compound is growing on the crack surface. We assume that there is sufficient time for the chemical process to form a protective film that fully covers the crack surface. This temporarily interrupts the corrosion process. During the application of next load cycle the stretch of the surface breaks the protective film. This creates gaps in the film, which allow dissolution of the underlaying metal. The chemical environment of the crack tip is assumed to be constant and unaffected by the changing geometry as the crack is developing. We assume that there is a linear relationship between strain and corrosion rate, in the sense of removed material per unit of area during each load cycle. The model simulates how dissolution lead to surface roughness, how pits form and grow to become cracks in one continuous process. The resulting natural variation of lengths of the formed cracks causes the cracks to grow with different speeds. During continuation one crack after the other falls into a wake behind a larger crack. Thus, crack tip load of the smaller decreases and finally causes crack arrest: At the end of the simulation only one growing crack remains. The results are compared with experimental observations
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
- …
