1,721,021 research outputs found
Homogenization of some linear and nonlinear partial differential equations [Elektronisk resurs]
No full textIn this thesis is studied two-scale convergence for sequences of linear and nonlinear evolution problems. In particular homogenization procedures, correctors and a numerical algorithm for such problems are studied. The main results are the following: We prove a crucial compactness results of two-scale convergence type. The compactness result is used to homogenize and prove corrector results for nonlinear parabolic problems with nonperiodic coefficients which oscillate with different speeds in the time and space variables. Moreover, we derive a numerical algorithm for this kind of problems. We prove compactness results of two-scale type, useful for homogenizing the linear Maxwell equations. We homogenize Maxwell´s equations by the use of two-scale convergence and prove some new corrector results. We prove two-scale compactness results applicable to nonlinear Maxwell´s systems. We define and characterize some function spaces which are well suited for Maxwell´s equations equipped with nonlinear constitutional relations. We prove the existence of a unique solution to the Maxwell system when the electric conductivity is uniformly monotone. Moreover, we homogenize the system and prove new corrector results in the case of nonperiodic coefficients. We prove a compactness result of two-scale type useful for Maxwell´s equations in the case of nonlinear permittivity and magnetic permeability. We prove the existence of solutions and homogenize and prove new corrector results for the Maxwell equations describing electromagnetic fields in nonperiodic materials with nonlinear permeability, permittivity and conductivity. We give some new examples of applications for homogenized linear and nonlinear Maxwell´s equations, e.g., the induced polarization phenomenon which is extensively used in prospecting for impregnation ores, ceramic varistors which are used as devices to protect electrical equipment against overvoltages, nonlinear optical applications and semiconductors in general.</p
Homogenization of quasiperiodic structures and two-scale cut-and-projection convergence
No full textNon UBCUnreviewedAuthor affiliation: Swedish Defence Research Agency, FOIOthe
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
Homogenization of some linear and nonlinear partial differential equations
No full textIn this thesis is studied two-scale convergence for sequences of linear and nonlinear evolution problems. In particular homogenization procedures, correctors and a numerical algorithm for such problems are studied. The main results are the following: We prove a crucial compactness results of two-scale convergence type. The compactness result is used to homogenize and prove corrector results for nonlinear parabolic problems with nonperiodic coefficients which oscillate with different speeds in the time and space variables. Moreover, we derive a numerical algorithm for this kind of problems. We prove compactness results of two-scale type, useful for homogenizing the linear Maxwell equations. We homogenize Maxwell´s equations by the use of two-scale convergence and prove some new corrector results. We prove two-scale compactness results applicable to nonlinear Maxwell´s systems. We define and characterize some function spaces which are well suited for Maxwell´s equations equipped with nonlinear constitutional relations. We prove the existence of a unique solution to the Maxwell system when the electric conductivity is uniformly monotone. Moreover, we homogenize the system and prove new corrector results in the case of nonperiodic coefficients. We prove a compactness result of two-scale type useful for Maxwell´s equations in the case of nonlinear permittivity and magnetic permeability. We prove the existence of solutions and homogenize and prove new corrector results for the Maxwell equations describing electromagnetic fields in nonperiodic materials with nonlinear permeability, permittivity and conductivity. We give some new examples of applications for homogenized linear and nonlinear Maxwell´s equations, e.g., the induced polarization phenomenon which is extensively used in prospecting for impregnation ores, ceramic varistors which are used as devices to protect electrical equipment against overvoltages, nonlinear optical applications and semiconductors in general.Godkänd; 1998; 20061123 (haneit
On the integral equation approach to solve Maxwell's equations
No full textThe electromagnetic field response, caused by an inhomogeneity in a homogeneous isotropic full space, is modelled and discussed. Maxwell's equations are solved by using Green's method which leads to a singular inhomogeneous Fredholm integral equation of the second kind. This equation contains some serious difficulties related to the evaluation of singular integrals when doing standard point collocation discretization. We state and prove a result, which avoids these diffi-culties. We also discuss some other attempts to avoid these difficulties in the literature.</p
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
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