1,721,324 research outputs found
Cystic dilatation of the common bile duct. Difficult preoperative diagnosis. Apropos of a case
No full textComponenti a microonde per la linea di trasmissione dell'impianto LH per ITER
No full textA study involving high power trans-
mission line components is presented. First, a
combiner/splitter mode converter to maximize the
power transfer capability of the transmission line,
has been deeply analyzed. We demonstrate the in-
ecaciousness of such component, forcing the trans-
mission line system to be designed in oversized rect-
angular waveguides with apposite mode lters atten-
uating non-fundamental modes. Further, the design
of bends has been considered, minimizing the power
dispersion and the excitation of higher order modes
Microwave Components for the Lower Hybrid Transmission Line of ITER
No full textIn this paper the analysis and design of
the transmission line for the International Thermonuclear
Experimental Reactor system is presented. In particular,
three types of innovative microwave devices have been
studied, all of them working in oversized waveguides: a
high power combiner/splitter, different bends, and mode
filters. Each of them has been analyzed in relevant
specific settings and conditions. The whole system is
designed in order to allow both a very high power
capability, low transmission losses, and very limited
generation of higher order modes
Validation of Lower Hybrid coupling codes (Brambilla, GRILL3D-U,TOPLHA) with the FTU conventional grill
No full textdesign were continuously pursued in view of ITER severe edge conditions. The excitation of LH waves by means of a phased waveguide array was initially proposed in 1974 by Lallia. A systematic study of the coupling problem related to this launching structure was firstly done by Brambilla in 1976 under the so-called grill theory. Subsequently, more detailed analyses were performed, still adopting several approximations in order to simplify the problem, such as the absence of mode conversion and 2D antenna models. The following studies developed more sophisticated models, for instance taking into account new antenna concepts, fast wave excitation, finite poloidal dimensions, etc. At the same time, numerical tools implementing theoretical models were developed; they were essentially based on mode matching technique, single-pass approximation and a slab plasma model. From the antenna viewpoint, the first codes could handle very simple antenna geometries, which then considerably increased in complexity. Lately, due to remarkable developments in computational electromagnetic techniques, new codes, totally or partially based on full-wave antenna solvers, appeared too. This paper validates three LH coupling codes based on different solving techniques: TOPLHA, GRILL3D-U, Brambilla code. They have been run to compute the coupling between the LH waves, launched by a row of the independently phased waveguide array antenna (conventional grill), and some FTU plasmas. TOPLHA and GRILL3D-U have been already compared with another well-established code, i.e. ALOHA, in the frame of the EFDA task HCD-08-03-01, where the LH antenna, proposed for ITER, was used as benchmark. Furthermore a validation of TOPLHA, GRILL3DU and the Brambilla code has been recently done as regards to the FTU conventional grill in terms of average reflection coefficients. In this paper a more detailed analysis is presented by comparing simulated curves with experimental data, that refer to the reflection coefficients effectively measured at the antenna mouth by built-in directional couplers
Microwave components for the lower hybrid transmission line of ITER
No full textIn this paper the analysis and design of the transmission line for the International Thermonuclear Experimental Reactor system is presented. In particular, three types of innovative microwave devices have been studied, all of them working in oversized waveguides: a high power combiner/splitter, different bends, and mode filters. Each of them has been analyzed in relevant specific settings and conditions. The whole system is designed in order to allow both a very high power capability, low transmission losses, and very limited generation of higher order modes. © 2010 IEICE Institute of Electronics Informati
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
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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