1,721,098 research outputs found
Nonlinear degenerate parabolic equations with irregular initial data
No full textExistence and regularity results for a class of degenerate nonlinear parabolic equations are proved for irregular initial data like the Dirac mass. Indeed the diffusion operator may degenerate as the solution diverges and may depend on space and time variables in a non-regular way, too
Regularity and time behavior of the solutions to weak monotone parabolic equations
No full textIn this paper, we study the behavior in time of the solutions for a class of parabolic problems including the p-Laplacian equation and the heat equation. Either the case of singular or degenerate equations is considered. The initial datum u is a summable function and a reaction term f is present in the problem. We prove that, despite the lack of regularity of u, immediate regularization of the solutions appears for data f sufficiently regular and we derive estimates that for zero data f become the known decay estimates for these kinds of problems. Besides, even if f is not regular, we show that it is possible to describe the behavior in time of a suitable class of solutions. Finally, we establish some uniqueness results for the solutions of these evolution problems
Existence and uniqueness for a class of nonlinear elliptic equations with measure data
No full textWe study existence and uniqueness of Radon measure-valued solutions for a class of nonlinear elliptic equations in inhomogeneous media. Solutions are constructed by a regularization procedure which relies on a standard approximation of the measure data and satisfy both a persistence property and a compatibility condition prescribing the structure of their concentrated and diffuse parts with respect to a suitable capacity
Regularity results and asymptotic behavior for a noncoercive parabolic problem
No full textIn this paper we study the regularity and the behavior in time of the solutions to a quasilinear class of noncoercive problems whose prototype is {ut-div(a(x,t,u)∇u)=-div(uE(x,t))inΩ×(0,T),u(x,t)=0on∂Ω×(0,T),u(x,0)=u0(x)inΩ. In particular we show that under suitable conditions on the vector field E, even if the problem is noncoercive and although the initial datum u is only an L1(Ω) function, there exist solutions that immediately improve their regularity and belong to every Lebesgue space. We also prove that solutions may become immediately bounded. Finally, we study the behavior in time of such regular solutions and we prove estimates that allow to describe their blow-up for t near zero
On the behavior in time of solutions to Motion of Non-Newtonian fluids
Get PDFWe study the behavior on time of weak solutions to the non-stationary motion of an incompressible fluid with shear rate dependent viscosity in bounded domains when the initial velocity .
Our estimates show the different behavior of the solution as the growth condition of the stress tensor varies. In the "dilatant" or "shear thickening" case we prove that the decay rate does not depend on , then our estimates also apply for irregular initial velocity
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
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