1,721,006 research outputs found
The existence of solutions for dynamic inclusions on time scales via duality
No full textAbstractThe problem of the existence of solutions to nabla differential equations and nabla differential inclusions on time scales is considered. Under a special form of the set-valued constraint map, sufficient conditions for the existence of at least one solution, that stays in the constraint set, are derived
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
Analysis of a Shear beam model with suspenders in thermoelasticity of type III
No full textWe conduct an analysis of a one-dimensional linear problem that describes the vibrations of a connected suspension bridge. In this model, the single-span roadbed is represented as a thermoelastic Shear beam without rotary inertia. We incorporate thermal dissipation into the transverse displacement equation, following Green and Naghdi’s theory. Our work demonstrates the existence of a global solution by employing classical Faedo–Galerkin approximations and three a priori estimates. Furthermore, we establish exponential stability through the application of the energy method. For numerical study, we propose a spatial discretization using finite elements and a temporal discretization through an implicit Euler scheme. In doing so, we prove discrete stability properties and a priori error estimates for the discrete problem. To provide a practical dimension to our theoretical findings, we present a set of numerical simulations.This research is part of first author’s Ph.D., which is carried out at Ferhat Abbas Sétif 1 University. Chabekh is grateful to the financial support of Ferhat Abbas Sétif 1 University, Algeria, for a one-month visit to the R&D Unit CIDMA, Department of Mathematics, University of Aveiro. The hospitality of the host institution is here gratefully acknowledged. Torres is supported by the Portuguese Foundation for Science and Technology (FCT) within project UIDB/04106/2020.publishe
Computação algébrica no cálculo das variações: determinação de simetrias e leis de conservação
No full textOs problemas de optimização dinâmica (em espaços de funções) tratados
pelo calculo das variações, são normalmente resolvidos por recurso às condições
necessárias de Euler-Lagrange, que são equações diferenciais de segunda ordem (ou
de ordem superior, quando os problemas variacionais envolvem derivadas de ordem
superior a um). Estas equações são, em geral, não lineares e de difícil resolução.
Uma forma de as simplificar consiste em obter leis de conservação: primeiros integrais
das equações diferenciais de Euler-Lagrange. Os primeiros integrais permitem
baixar a ordem das equações e, em casos extremos, com um número suficientemente
grande de primeiros integrais independentes, resolver o problema por completo. Se
em áreas como a Física e a Economia a questão da existência de leis de conservação
é resolvida de forma bastante natural, a própria aplicação sugerindo as leis de conservação (e.g. conservação de energia, conservação da quantidade de movimento,
conservação do rendimento, etc.), de um ponto de vista estritamente matemático,
dado um problema do calculo de variações, o processo de obtenção das leis de conservação ou, até mesmo, a demonstração de que elas existem (ou não), deixa de ser
uma questão óbvia. Neste trabalho mostramos como um sistema de computação
algébrica como o Maple pode ser muito útil na abordagem a estas questões. Apresentamos
um conjunto de facilidades computacionais simbólicas que permitem,
de uma forma sistemática e automática, identificar as leis de conservação de uma
dada funcional integral do calculo das variações. O algoritmo usado tem por base o
célebre teorema de Emmy Noether, que associa a existência de leis de conservação
`as propriedades de invariância do problema (à existência de simetrias variacionais).
Vários exemplos ilustrativos são apresentados, mostrando a utilidade das ferramentas desenvolvidas
Smarandache sequences: explorations and discoveries with a computer algebra system
Get PDFWe study Smarandache sequences of numbers, and related problems,
via a Computer Algebra System. Solutions are discovered, and some
conjectures presented
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