1,720,970 research outputs found
47)I derivati fenolici nelle medicazioni intermedie in endodonzia: revisione della letteratura.
No full textExperimental investigation and characterization of the rotating stall in a high pressure centrifugal compressor. Part IV: Impeller influence on diffuser stability
No full textVaneless diffuser rotating stall is a major problem for centrifugal compressors since it is a limit to their working range. In particular the last stage seems to be the most critical. In the literature some good correlations for predicting stall inception can be found but they do not adequately cover the case of the last stage configuration, especially for very low blade-outlet-width-to-impeller-radius-ratio impellers typically used in high-pressure applications. Extensive research has been performed to define diffuser stall limits for this family of stages: three impellers characterized by different blade-outlet-width-to-impeller-radius-ratios are tested with different diffuser configurations (different pinch shapes, diffuser widths and diffusion ratios). Part I and II report the results of these geometry modifications on diffuser stability for the first impeller. Part III, those for the second impeller. In this part the comparison of these results in terms of impeller influence on diffuser stability is reported
Experimental investigation and characterization of the rotating stall in a high pressure centrifugal compressor. Part III: Influence of diffuser geometry on stall inception and performance (2nd impeller tested)
No full textVaneless diffuser rotating stall is a serious problem for centrifugal compressors since it limits their working range. In particular the last stage seems to be the most critical from this point of view. In the literature some good correlations can be found for predicting stall inception but they hardly cover the case of last stage configuration, especially for very low blade-outlet-width-to-impeller-radius-ratio impellers typically used in high-pressure applications. Extensive research has been planned to define diffuser stall limits for this family of stages: three impellers characterized by different blade-outlet-width-to-impeller-radius-ratios are tested. The basic configuration comprises a 1:1 geometrical scale stage with a return channel upstream, a 2D impeller with a vaneless diffuser and a volute with a constant cross sectional area downstream. Several diffuser types with different widths, pinch shapes and diffusion ratios were tested. The results for the first impeller have already been reported in part I and II. In this part the effects of the above mentioned geometric parameter changes on stage stability and performance are presented with respect to the second impeller
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
Qualcosa è cambiato: dati e analisi sull’organizzazione intra-partitica dal Pci al Pds-Ds
No full textL'articolo ricostruisce il passaggio dal PCI al Pds-Ds secondo un approccio organizzativo e multidimensionale all'analisi del mutamento dei partiti. L'obiettivo è quello di superare l'approccio tradizionale fondato sui "modelli di partito", per proporre una nuova prospettiva in grado di cogliere in modo più puntuale la complessità delle forme organizzative che i partiti possono adottare. Attraverso il confronto degli statuti, il presente lavoro mira a comparare la disintermediazione intra-partitica nell'arco temporale che va dagli anni Settanta agli anni Duemila
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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