1,720,970 research outputs found
An Efficient Method to Take into Account Forecast Uncertainties in Large Scale Probabilistic Power Flow
No full textThe simulation of uncertainties due to renewable and load forecasts is becoming more and more important in security assessment analyses performed on large scale networks. This paper presents an efficient method to account for forecast uncertainties in probabilistic power flow (PPF) applications, based on the combination of PCA (Principal Component Analysis) and PEM (Point Estimate Method), in the context of
operational planning studies applied to large scale AC grids. The benchmark against the conventional PEM method applied to large power system models shows that the proposed method assures high speed up ratios, preserving a good accuracy of the marginal distributions of the outputs
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
Performance analysis of frequency regulation services provided by aggregates of domestic thermostatically controlled loads
No full textThis paper proposes a control method for allowing aggregates of thermostatically controlled loads to provide
synthetic inertia and primary frequency regulation services to the grid. The proposed control framework is fully
distributed and basically consists in the modification of the thermostat logic as a function of the grid frequency.
Three strategies are considered: in the first one, the load aggregate provides synthetic inertia by varying its active
power demand proportionally to the frequency rate of change; in the second one, the load aggregate provides
primary frequency regulation by varying its power demand proportionally to frequency; in the third one, the two
services are combined. The performances of the proposed control solutions are analyzed in the forecasted scenario
of the electric power system of Sardinia in 2030, characterized by a huge installation of wind and
photovoltaic generation and no coil and combustible oil power plants. The considered load aggregate is
composed by domestic refrigerators and water heaters. Results prove the effectiveness of the proposed approach
and show that, in the particular case of refrigerators and water heaters, the contribution to the frequency
regulation is more significant in the case of positive frequency variations. Finally, the correlation between the
regulation performances and the level of penetration of the load aggregate with respect to the system total load is
evaluated
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
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