1,721,203 research outputs found
Towards Modeling and Simulation of Dynamic Overconstrained Connectors in Modelica
Full text linkCyber-Physical Systems are ever-increasing in complexity and new methods and tools for developing them are needed. To support these highly dynamic systems, increasing the flexibility of the modeling languages is desirable. This paper proposes and examines a Modelica language extension to support dynamic overconstrained graphs with reconfiguration at runtime. Two applications of this new feature are also discussed: synchronous AC power systems and incompressible fluid networks. Reported findings suggest that supporting dynamic overconstrained graphs might yield performance benefits and provide the possibility of simulating systems that can not currently be simulated in existing Modelica tools.</p
A New OpenModelica Compiler High Performance Frontend
Full text linkThe equation-based object-oriented Modelica language allows easy composition of models from components. It is very easy to create very large parametrized models using component arrays of models. Current open-source and commercial Modelica tools can with ease handle models with a hundred thousand equations and a thousand states. However, when the system size goes above half a million (or more) equations the tools begin to have problems with scalability. This paper presents the new frontend of the OpenModelica compiler, designed with scalability in mind. The new OpenModelica frontend can handle much larger systems than the current one with better time and memory performance. The new frontend was validated against large models from the ScalableTestSuite library and Modelica Standard Library, with good results
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
L’impact différencié de la faillite de Lehman Brothers sur les valeurs bancaires et financières américaines : une étude d’événement
No full textThe spectacular failure of the 150-year old investment bank Lehman Brothers has been perceived by many as a major turning point in the global financial crisis that broke out in the summer 2007. The specter of systemic risk raised fears of a full-scale collapse of the US financial sector due to financial contagion and concerns about significant disturbances outside the US, in international financial markets. Through the use of stock market data, this article examines the investors’ reaction to Lehman Brothers collapse in an attempt to identify a contagion effect on the surviving financial institutions. The empirical analysis indicates that (i) the collateral damages were limited to the largest financial firms ; (ii) the most affected institutions were the surviving “ non-bank” financial services firms (mortgage and specialty finance, investment services, and diversified financial services firms) ; (iii) the negative effect was strongly correlated with financial conditions of the surviving institutions.
Classification JEL : G21, G28.La faillite spectaculaire de la banque d’investissement Lehman Brothers a été perçue par de nombreux analystes comme un véritable point de retournement dans la crise financière actuelle. Le spectre du risque systémique a semé la panique parmi les investisseurs, non seulement aux États-Unis, mais aussi sur les marchés financiers internationaux. À l’aide de séries boursières sur le cours des actions des établissements financiers, nous analysons la perception de la faillite de Lehman Brothers aux États-Unis en étudiant la réaction des investisseurs à l’annonce de cet évènement spectaculaire et inattendu. Nos résultats montrent que les dommages collatéraux associés à cette faillite se sont fait sentir de manière significative dans plusieurs sous-groupes spécifiques d’institutions : (i) les entreprises spécialisées dans les services financiers proches du secteur d’activité de Lehman Brothers, mais aussi (ii) les plus grandes banques et entreprises financières, qui sont au coeur même du système financier, ainsi que (iii) les entreprises spécialisées dans les crédits immobiliers.
Classification JEL : G21, G28.Dumontaux Nicolas, Pop Adrian. L’impact différencié de la faillite de Lehman Brothers sur les valeurs bancaires et financières américaines : une étude d’événement. In: Revue d'économie financière, n°101, 2011. Le risque systémique 2. Repenser la supervision. pp. 261-272
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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