1,720,999 research outputs found
Optimal Control and Lyapunov exponents
No full textIl presente lavoro è suddiviso in due parti. Nella prima sono presentate la teoria degli esponenti di Lyapunov e la teoria del Controllo Ottimo da un punto di vista geometrico. Sono riportati
i risultati principali di queste due teorie e vengono abbozzate le dimostrazioni dei teoremi più importanti. Nella seconda parte, usando queste due teorie, abbiamo provato a trovare una stima
per gli esponenti di Lyapunov estremali associati ai sistemi dinamici lineari switched sul gruppo di Lie SL2(R). Abbiamo preso in considerazione solo il caso di un sistema generato da due matrici A,B ∈ sl2(R) che generano l’intera algebra di Lie. Abbiamo suddiviso il problema in alcuni possibili casi a seconda della posizione nello spazio tridimensionale sl2(R) del segmento di estremi A e B rispetto al cono delle matrici nilpotenti. Per ognuno di questi casi, abbiamo trovato una candidata soluzione ottimale. Riformuleremo il problema originale di trovare una stima per gli
esponenti di Lyapunov in un problema di Controllo Ottimo. Dopodiché, applichiamo il Principio del massimo di Pontryagin e troveremo un controllo e la corrispondente traiettoria che soddisfa
tale Principio
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
Introduction to optimal control theory
No full textThese are lecture notes of the introductory course in Optimal Control theory treated from the geometric point of view. Optimal Control Problem is reduced to the study of controls (and corresponding trajectories) leading to the boundary of attainable sets. We discuss Pontryagin Maximum Principle, basic existence results, and apply these tools to concrete simple optimal control problems. Special sections are devoted to the general theory of linear time-optimal problems and linear-quadratic problems
"Good Lie Brackets" for Control Affine Systems
No full textInternational audienceWe consider a smooth system of the form , and study controllability issues on the group of diffeomorphisms of . It is well-known that the system can arbitrarily well approximate the movement in the direction of any Lie bracket polynomial of . Any Lie bracket polynomial of is good in this sense. Moreover, some combinations of Lie brackets which involve the drift term are also good but surely not all of them. In this paper we try to characterize good ones and, in particular, all universal good combinations, which are good for any nilpotent truncation of any system
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
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