1,721,252 research outputs found
A note on closed degrees of difficulty of the Medvedev lattice
No full textWe consider some nonprincipal filters of the Medvedev lattice. We prove that the filter generated by the nonzero closed degrees of difficulty is not principal and we compare this filter, with respect to inclusion, with some other filters of the lattice. All the filters considered in this paper are disjoint from the prime ideal generated by the dense degrees of difficulty
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
Wulff shape characterizations in overdetermined anisotropic elliptic problems
Full text linkWe study some overdetermined problems for possibly anisotropic degenerate elliptic PDEs, including the well-known Serrin's overdetermined problem, and we prove the corresponding Wulff shape characterizations by using some integral identities and just one pointwise inequality. Our techniques provide a somehow unified approach to this variety of problems
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
Low-cost sensorless BLDC for organic fluids treatment in sterile environments
No full textThis paper presents the design and realization of a brushless DC motor-based gear pump for the treatment of organic fluids in sterile environments. Details of the FEM simulations used throughout the mechanical and electromagnetic design of the electrical machine and of the sensorless control algorithm, implemented on a motion control-oriented fixed point DSP, are reported. Construction and experimental testing of a prototype are reported as well. The realized pump features a very compact design and a fairly efficient operation. © 2008 IEEE
A Double Three-Phase Axial-Flux Synchronous Reluctance Motor
No full textIn this paper, an innovative double three-phase axial-flux synchronous reluctance motor is proposed. This configuration can be manufactured using metal additive manufacturing (AM). Thanks to the multi-phase solutions an high reliability is ensured and the chance to power separately the two stators can lead to some advantages in terms of torque ripple and MMF shape at the airgap. The traditional geometry is analyzed, and then a new solution is deepened with the purpose of reducing the saturation level in the rotor and the torque ripple. At the same time an improvement of the torque density per unit volume is obtained thanks to the innovative simplified design. The rotor geometry is simplified and the total machine volume is reduced. 2D and 3D simulations results are provided in the paper
A Synthetic Nickel Electrocatalyst with Turnover Frequency Above 100,000 s-1 for H2 Production
No full textThe break-through article “A Synthetic Nickel Electrocatalyst with a Turnover Frequency Above 100 000 s−1 for H2 Production” by Monte L. Helm et al. (Science2011, 333, 863) presents results of great interest in the field of hydrogen production, in view of a fantastic turnover frequency obtained by an elegant catalyst design, inspired by nature, and the use of a largely available and cheap metal
Wikidata alla Fondazione Levi di Venezia. Il caso di studio del Fondo Gambara
Full text linkL’articolo presenta un caso di studio per la pubblicazione su Wikidata dei dati del Fondo Gambara, raccolta grafica composta da duecento-due ritratti, prevalentemente di musicisti della fine dell’Ottocento conservata presso la Fondazione Ugo e Olga Levi di Venezia. Lo scopo dello studio era la sperimentazione della pubblicazione di un campione di dati del database Levidata su Wikidata e la definizione del flusso di lavoro ottimale da utilizzare in modo più esteso per la pubblicazione progressiva dei dati di tutti i fondi rilevanti individuati. L’articolo presenta le fasi del processo di pubblicazione dei dati: individuazione e raccolta, analisi ed elaborazione dello schema delle proprietà di Wikidata, riconciliazione, caricamento e controllo. Si discutono infine i risultati raggiunti e i vantaggi attesi e ottenuti dalla pubblicazione dei dati su Wikidata.A case study on the publication on Wikidata of the dataset of Fondo Gambara, a collection of 202 portraits mostly of musicians of the XIX century held at Fondazione Ugo e Olga Levi (Venice, Italy), is presented. The purpose of the case study was to test the publication of data from Levidata on Wikidata and to define the best workflow to be implemented in larger scale for the publication of data of any relevant collection of Fondazione Levi. The paper illustrates each step of the publication process of the data: data individuation and harvesting, analysis and elaboration of Wikidata properties schema, reconciliation, uploading, and final testing. Results of the process, expected advantages, and obtained achievements of the data publication on Wikidata are also discussed
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