1,720,956 research outputs found
New Remedial Approaches to the Breakdown of Lanczos-type Algorithms
Full text linkThere are numerous algorithms for the solution of systems of linear equations and eigenvalue problems. Among such methods, one of the best known iterative schemes is the Lanczos algorithm. It has however, a very serious shortcoming in that it break down frequently before achieving convergence to an acceptable solution. This project focuses on investigating this breakdown issue. There are a number of attempts to address it. Restarting and Switching as implemented previously by Farooq and Maharani, which rely on guessing the appropriate number of iterations before halting the Lanczos process and restarting it or switching to a different one. This guess is very sensitive to the type of problem solved, its data and size. If underestimated then the process is stopped too early, too often. This means that a lot of stable iterations are wasted, potentially. If, on the other hand, this number is over-estimated, then the process will breakdown which means that restarting and / or switching will be more costly. The aim of this thesis is to avoid guessing the number of iteration by monitoring the parameters of the recurrence relations on which the given Lanczos-type algorithms are based, which cause breakdown. This monitoring is targeted to the appropriate or problematic parameters. In this thesis we show that this approach is effective as it does not require too much extra work. At the same time it cuts on the wasted iterations and the full blown breakdown caused by inaccurate guesses of the number of iterations one has to let the algorithm run before halting it. Although this is the core of our contributions in this thesis, we have also suggested new Lanczos-type algorithms and tested them against existing ones. This work complements that of Farooq, Mahrani, Baheux and the Brezinski team. The results show that we have made Lanczos-type algorithms old and new more reliable and robust
The computation of matrix functions in particular, the matrix exponential
No full textMatrix functions in general are an interesting area in matrix analysis and are used in many areas of linear algebra and arise in numerous applications in science and engineering. We consider how to define matrix functions and how to compute matrix functions. To be concrete, we pay particular attention to the matrix exponential. The matrix exponential is one of the most important functions of a matrix. In this thesis, we discuss some of the more common matrix functions and their general properties, and we specifcally explore the matrix exponential. In principle, there are many different methods to calculate the exponential of a matrix. In practice, some of the methods are preferable to others, but none of which is entirely satisfactory from either a theoretical or a computational point of view. Computations of the matrix exponential using Taylor Series, Pade Approximation, Scaling and Squaring, Eigenvectors and Schur Decomposition methods are provided. In this project we checked rate of convergence and accuracy of the matrix exponential
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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