1,720,959 research outputs found
Variational linear problems in wave- obstacle interaction.
No full textWe discuss the problem of the steady two-dimensional flow past fixed disturbances
in an open channel of finite depth. We consider different types of obstacles: submerged or
surface-piercing bodies and localized perturbations of a horizontal bottom. By a special variational
approach, we prove the unique solvability of the linearized problem for supercritical
velocities of the unperturbed flow. We also discuss extensions of the variational method to the
limit case of a submerged beam and to subcritical velocities
Concentration along geodesics for a nonlinear Steklov problem arising in corrosion modeling
No full textWe consider the problem of finding pairs (λ, u), with λ > 0 and u a harmonic function in a three-dimensional torus-like domain D, satisfying the nonlinear boundary condition ∂νu = λ sinh u on ∂D. This type of boundary condition arises in corrosion modeling (Butler-Volmer condition). We prove the existence of solutions which concentrate along some geodesics of the boundary ∂D as the parameter λ goes to zero
Nonlinear equations: methods, models and applications. Proceedings of the 3rd International Workshop on Nonlinear Analysis and Applications held in Bergamo, July 9--13, - Progress in Nonlinear Differential Equations and their Applications
No full textFor semilinear partial differentizl equations of mixed elliptic- hyperbolic type with various boundary condiions, the nonexistence of nontrivial solutions is shown for domains which are suitably star shaped and for nonlinearities with supercritical grouth in a suitable sense. The results follow from integral identities of Pohozaev type which are suitably calibrated to an invariance with respect to anisotropic dilation in the linear part of the equation. For the Dirchlet problem, in which the boundary condition is placed on the entire boundary, the techniques is completely analogous to the classical elliptic case as firsdt developed by Pohozaev [34]in the supercritical case. At critical growth , the nonexistence principle is established by combining the dilation identity with another energy identity. For "open" boundary value problems in which the boundary condition is placed on a proper subset of the boundary, sharp Hardy-Sobolev inequalities are used to control terms in the integral identity corresponding to the lack of a boundary condition as was first done in [23] for certain two dimensional problems
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
- …
