1,721,492 research outputs found
On the Approximation of Miscible Displacement in Porous Media by a Method of Characteristics Combined with a Mixed Method
No full textDuran, R.. (1986). On the Approximation of Miscible Displacement in Porous Media by a Method of Characteristics Combined with a Mixed Method. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/4496
Sharp Maximum Norm Error Estimates for Finite Element Approximations of the Stokes Problem in 2-D
No full textDuran, R.; Nochetto, R.H.; Wang, J.. (1987). Sharp Maximum Norm Error Estimates for Finite Element Approximations of the Stokes Problem in 2-D. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/4586
Computing k different solutions to the assignment problem
No full textAssignment problems are about the best way of matching the elements of a first set with the elements of a second set. In Semi-Assignment problems, more than one element of the first set can be assigned to each element of the second. In many situations, a solution to the same Assignment or Semi-Assignment problem has to be implemented more than once, and for a fairness reason it may not be desirable to always implement the same solution. Another common situation is when more than a single solution to the (Semi-)Assignment has to be generated, so as to give the decision maker a portfolio of options to choose in. This can happen because not all the problem constraints could be considered in the problem formulation, and the decision maker may want to choose between alternative solutions. In both cases, one is interested in defining several alternative solutions to the problem, still optimizing their cost. In this paper we discuss two specific situations for which we present optimization algorithms. The algorithms are computationally tested on a set of instances from the literature and from a real world application
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
Analysis of finite element approximations of stokes equations with nonsmooth data
Full text linkIn this paper we analyze the finite element approximation of the Stokes equations with nonsmooth Dirichlet boundary data. To define the discrete solution, we first approximate the boundary datum by a smooth one and then apply a standard finite element method to the regularized problem. We prove almost optimal order error estimates for two regularization procedures in the case of general data in fractional order Sobolev spaces and for the Lagrange interpolation (with appropriate modifications at the discontinuities) for piecewise smooth data. Our results apply in particular to the classic lid-driven cavity problem, improving the error estimates obtained in Cai and Wang [Math. Comp., 78 (2009), pp. 771-787]. Finally, we introduce and analyze an a posteriori error estimator. We prove its reliability and efficiency and show some numerical examples which suggest that optimal order of convergence is obtained by an adaptive procedure based on our estimator
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