1,720,981 research outputs found
Exakte und sanfte Rekonstruktion von strukturierten Signalen mittels atomischer und totaler Variation-Normminimierung
No full textThis thesis treats regularization techniques of inverse problems using TV- and atomic norms. In the first part of the thesis, the two concepts are connected, making a unified treatment in the rest of the thesis possible. Concretely, it is proven that for reasonable dictionaries, atomic norms can be calculated with the help of TV -minimization, and that the TV -norm can be considered as an atomic norm with respect to a special dictionary in a Hilbert space. The theory is formulated in an infinite-dimensional setting - finite dimensional examples are however also included as subcases. In the following chapter, a result on the structure of solutions of TV -regularized problems is proven. Formulated and proven in an abstract setting, it states that in most cases, there will exist sparse solutions of the TV -regularized problems. In the chapter thereafter, exact recovery guarantees are discussed. The main aim of that chapter is to provide a link between TV -minimization and atomic norm-minimization with respect to certain dictionaries in so-called reproducible Kernel Hilbert spaces. These results are then applied to produce recovery guarantees for measurement models not previously treated in the literature. In the chapter thereafter, the framework of soft recovery is developed. A method is presented to prove approximate support recovery guarantees. This is first formulated in a very general manner, and then applied to numerous examples. New results on the recoverability of large peaks in standard, finite dimensional dictionary sparse recovery is proven, as well as soft recovery guarantees for several different types of superresolution problems. In the final chapter, methods for numerical resolution of infinite dimensional TV-regularized problems are discussed. The main novel finding is a connection between grid discretization of the TV -regularized problem and linearization of the operator used to probe the signal.Diese Doktorarbeit behandelt Regularisierungstechniken für inverse Probleme, die TV- und atomische Normen verwenden. Im ersten Tail der Arbeit werden die beiden Konzepte verbunden, so dass eine einheitliche Behandlung in den weiteren Teilen der Arbeit möglich ist. Konkret wird bewiesen dass atomische Norme für vernünftige Dictionaries mittels TV-minimierung berechnet werden können, und dass die TV-Norm als eine atomische Norm bezüglich eines bestimmten Dictionary in einem Hilbertraum aufgefasst werden kann. Die Theorie wird in einem unendlichdimensionalen Rahmen formuliert, endlichdimensionale Beispiele sind allerdings auch als Spezialfälle inkludiert. Im darauffolgenden Kapitel wird ein Resultat zur Struktur von Lösungen von TV-regularisierte Probleme bewiesen. Das Resultat wird in einem abstrakten Rahmen formuliert und bewiesen, und sagt aus, dass es in den meisten Fällen dünn besetzte Lösungen existieren. Im Kapitel danach werden exakte Rekonstruktionsgarantien diskutiert. Das Hauptzeil dieses Kapitels ist es, eine Verbindung zwischen TV-Minimierung und atomische Norm-Minimierung bezüglich bestimmte Dictionaries in sogenannten Reproducing Kernel-Hilberträume herzustelen. Diese Resultate werden danach verwendet, um Rekonstruktionsgarantien zu erzeugen für Messmodelle, die bisher nicht betrachtet wurden. Im nächsten Kapitel wird das Konzept der sanften Rekonstruktion entwickelt. Es wird eine Methode vorgestellt, die verwendet werden kann, um approximative Trägerrekonstruktionsgarantien zu beweisen. Diese wird zunächst in einer sehr allgemeinen Form formuliert, und anschließend an mehreren Beispielen appliziert. Es werden sowohl eue Resultate zur Rekonstruktionsmöglichkeit von große Komponenten in endlichdimensionale Dictionary-dünn-besetzte Signale, als auch sanfte Rekonstruktionsgarantien für mehrere Arten von Superresolutionsprobleme bewiesen. Im letzten Kapitel werden Methode zur numerischen Lösung von unendlichdimensionale TV-regularisierte Probleme diskutiert. Das hauptsächliche neue Erkenntnis ist die Herstellung einer Verbindung zwischen Gitterdiskretizierung vom TV-regularisierten Problem und eine Linearisierung des Operators, die für die Messung der Signale verwendet wird
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Iterative Discretization of Optimization Problems Related to Superresolution
No full textInternational audienceWe study an iterative discretization algorithm for solving optimization problems regularized by the total variation norm over the space M(Ω) of Radon measures on a bounded subset Ω of R d. Our main motivation to study this problem is the recovery of sparse atomic measures from linear measurements. Under reasonable regularity conditions, we arrive at a linear convergence rate guarantee
Iterative Discretization of Optimization Problems Related to Superresolution
No full textInternational audienceWe study an iterative discretization algorithm for solving optimization problems regularized by the total variation norm over the space M(Ω) of Radon measures on a bounded subset Ω of R d. Our main motivation to study this problem is the recovery of sparse atomic measures from linear measurements. Under reasonable regularity conditions, we arrive at a linear convergence rate guarantee
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