1,359,138 research outputs found
FREDE: Anytime Graph Embeddings
No full textLow-dimensional representations, or embeddings, of a graph's nodes facilitate
several practical data science and data engineering tasks. As such embeddings
rely, explicitly or implicitly, on a similarity measure among nodes, they
require the computation of a quadratic similarity matrix, inducing a tradeoff
between space complexity and embedding quality. To date, no graph embedding
work combines (i) linear space complexity, (ii) a nonlinear transform as its
basis, and (iii) nontrivial quality guarantees.
In this paper we introduce FREDE (FREquent Directions Embedding), a graph
embedding based on matrix sketching that combines those three desiderata.
Starting out from the observation that embedding methods aim to preserve the
covariance among the rows of a similarity matrix}, FREDE iteratively improves
on quality while individually processing rows of a nonlinearly transformed PPR
similarity matrix derived from a state-of-the-art graph embedding method} and
provides, at any iteration, column-covariance approximation guarantees in due
course almost indistinguishable from those of the optimal approximation by SVD.
Our experimental evaluation on variably sized networks shows that FREDE
performs almost as well as SVD and competitively against state-of-the-art
embedding methods in diverse data science tasks, even when it is based on as
little as 10% of node similarities.Comment: As appeared in VLDB 1
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The Seventh Letter: A Discussion of Myles Burnyeat and Michael Frede, The Pseudo-Platonic Seventh Letter
No full textBurnyeat and Frede argue that the seventh of the letters ascribed to Plato is no more genuine than any other letter purporting to be from a philosopher before Epicurus; that its true author is far too remote from Plato for it to give any reliable evidence about Plato’s thoughts and activities; and that it is to be appreciated as a fine tragedy in prose. This review criticizes some of the details of their arguments, while endorsing and amplifying their conclusion
Una causa dibattuta a Napoli per acquisto di libri nel 1469
No full textDe Frede Carlo. Una causa dibattuta a Napoli per acquisto di libri nel 1469. In: Scriptorium, Tome 10 n°2, 1956. pp. 259-261
Global goals for a better and more sustainable world demanding electrification and power electronics
No full textEn este número de In Genium dedicado a los Objetivos de Desarrollo Sostenibles (ODS) definidos por la ONU, desde la Sección de Ing. Eléctrica, Electrónica e Informática, invitamos al Prof. Frede Blaabjerg, de la Universidad de Aalborg en Dinamarca, a escribir un artículo para la revista. El Prof. Blaabjerg ha trabajado por más de 30 años en temas de Electrónica de Potencia aplicada a sistemas de energía y accedió gentilmente a escribir un artículo especial para In-Genium.Academia de la Ingeniería de la provincia de Buenos Aire
Michael Frede, A Free Will. Origin of the Notion in Ancient Thought
No full textLe décès de Michael Frede en 2007 avait laissé inédites six leçons données par lui à l’Université de Californie au titre de 84th Sather Professor of Classical Literature (1997-1998). La parution d’une version définitive de ces leçons était prévue dès l’origine dans les Sather Classical Lectures Series, mais avait été sans cesse repoussée par M. Frede, qui manifestement souhaitait constituer un complément de recherche pour livrer au public une thèse originale pleinement étayée. Il s’agissait e..
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Virtual inertia operation of renewables
No full textThe synchronous rotating inertia is the key parameter of power system stability. Increasing the penetration of nonsynchronous generators, e.g., wind turbine, photovoltaics, and energy storage system, in the power grids leads to some stability challenges due to the lack of rotating mass and kinetic inertia in the system. In this chapter, the effect of high penetration of renewables on power system stability is shown. Moreover, the recent low-inertia grid challenges in Europe and South Australia are presented. Technically, in order to achieve 100% renewables, providing virtual inertia is a demand. The virtual synchronous machine (VSM) is a promising solution to emulate the behavior of a synchronous machine and provide inertia virtually. In this chapter, the theoretical concept of VSM, as well as the control structure, is also presented. Furthermore, the VSM implementation in the power system is explained, and some RMS simulation results are provided in a fault situation. Since in a controller based on the swing equation, the current is not controlled in the short time frame directly, a current limitation controller is also implemented in VSM and scrutinized in this chapter.</p
Single-Phase Induction Motor and AC Drives
No full textThis chapter presents the working principle and modeling of the single-phase induction motor (SPIM), as well as the control strategies of the SPIM with several different power electronics device-based variable frequency AC drives. The SPIM has been widely used for the water pumps, compressors, and fans with no tough demand for high performance and they are especially used at small-rated power below 1 kW. Besides the conventional single-phase main power supply, the SPIM can also be supplied by a single-phase or three-phase voltage source inverter. This chapter will first introduce the working principle of the SPIM, and then establish the modeling of the motor. Thereafter, this chapter will present theoretical analysis on how the SPIM performance is influenced by different supply methods, i.e., including the supply methods using a single-phase inverter with a running capacitor, or using a three-phase inverter with/without a running capacitor. Further comparisons will be made in terms of starting torque, starting current, pulsation torque, efficiency, etc. Simulation results are provided to compare and demonstrate the similarities and differences between these power electronics device-based variable frequency AC drives for SPIM
Phase-locked loops and their design
No full textThis chapter provides a comprehensive overview of the recent attempts for designing of the advanced three-phase and single-phase phase-locked loops (PLLs). The operating principle of both three-phase and single-phase PLLs is explained. Furthermore, the different features and applications of the PLLs are carefully discussed. Finally, the performance comparison guidance is provided and that could be a quick reference for proper selections of appropriate PLLs for researchers and engineers.</p
Variations on the Author
No full text“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
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