1,721,442 research outputs found
Petri nets with discrete phase timing: A bridge between stochastic and functional analysis
No full textThe addition of timing specification in Petri Nets (PN) has followed two main lines: intervals for functional analysis or stochastic durations for performance and dependability analysis. The present paper proposes a novel technique to analyze time or stochastic PN models based on discretization. This technique can be seen as a bridge between the world of functional analysis and the world of stochastic analysis. The proposed discretization technique is based on the definition of a new construct called Discrete Phase Type Timing - DPT that can represent a discrete cumulative density function (cdf) over a finite support (or a deterministic cdf) as well as an interval with non-deterministic choice (or a deterministic duration). In both views, a preemption policy can be assigned and a strong (the transition must fire when the interval expires) or a weak (the transition can fire when the interval expires) firing semantics. The paper introduces the DPT construct and shows how the expanded state space can be built up resorting to a compositional approach based on Kronecker algebra. With this technique a functional model can be quantified by adding probability measures over the firing intervals without modifying the (compositional) structure of the PN model
La démographie historique en deuil : Robert A. Horvath (1916-1993)
No full textDupâquier Jacques. La démographie historique en deuil : Robert A. Horvath (1916-1993). In: Annales de démographie historique, 1994. pp. 355-356
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
Fluid stochastic petri nets augmented with flush-out arcs: A transient analysis technique
No full textFluid Stochastic (or Hybrid) Petri Nets with flush-out arcs are Petri net-based models with two classes of places: discrete places that carry a natural number of distinct objects (tokens), and fluid places that hold a positive amount of fluid, represented by a real number. For this kind of formalisms, equations can be automatically derived from the model. Such equations, however, are often too complex to be solved analytically and simple discretization techniques usually can be successfully applied only to simple cases. In this paper, we present a particular solution technique for transient solution that makes use of Kronecker-algebra
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
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