1,720,960 research outputs found
Energy conservation and high-frequency damping in numerical time-integration
No full textMomentum and energy conserving time integration procedures are receiving increased interest due to the central role of conservation properties in relation to the problems under investigation. However, most problems in structural dynamics are based on models that are first discretized in space, en this often leads to a fairly large number of high-frequency modes, that are not represented well - and occasionally directly erroneously - by the model. It is desirable to cure this problem by devising algorithms that include the possibility of introducing algorithmic energy dissipation of the high-frequency modes. The problem is well known from classic collocation based algorithms - notably various forms of the Newmark algorithm where the equation of motion is supplemented by approximate relations between displacement, velocity and acceleration. Here adjustment of the algorithmic parameters can be used to introduce so-called alpha-damping, and an improved form leading only to high-frequency damping can be obtained by suitable averaging of the equilibrium equation at consecutive time steps. Conservative time integration algorithms are obtained by use of an integral of the equation of motion and the acceleration therefore does not appear as an independent parameter of these algorithms. Typically they do not contain algorithmic parameters either. Algorithmic damping can then be introduced in two ways: either by introducing artificial damping in terms of the displacement and velocity vectors, or by introducing additional variables to represent damping. In the present paper it is demonstrated, how damping equivalent to the alpha-damping of the Newmark algorithm can be introduced directly via displacement and velocity dependent terms. It is furthermore shown, how this damping can be improved by introduction of a new set of variables related to the displacement and velocity vectors by a suitable first order filter with scalar coefficients. By this device an algorithmic damping can be obtained that is of third order in the low-frequency regime. It is an important feature of both algorithms that they can be arranged to require in each time step only the solution of a system of equations of the same size of the corresponding quasi-static problem, followed by one or three vector updates with scalar coefficients - the so-called 'single step - single solve' property
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
A Study of the Historical Construction Technology of Bell Towers in Cyprus
No full textThis paper aims to present the historical construction technology of churches’ bell towers in Cyprus, starting with the initiation of their use and addressing the development of their distinctive morphology adapting and mixing various architectural styles. Traditional bell towers are tall and slender unreinforced masonry structures that are known to be particularly vulnerable to earthquake actions encountered in seismogenic regions, such as Cyprus. Therefore, iron and wood elements with high tensile capacities were commonly utilized in Cypriot bell towers in the form of ties. In particular, the bell tower of Saint John’s church in Psevdas village was constructed using such technology and is an example case studied in more detail in the present work. This tower suffered a partial collapse during an earthquake on May 12th, 2016 and underwent restoration within the next year. Based on the knowledge gathered from the case of the damaged tower and the visual inspection of other bell towers in Cyprus, the use of timber and iron ties in these masonry structures is deemed to be essential for their protection from seismic actions
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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