1,721,056 research outputs found
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
Preliminary integrated core-SOL-divertor modelling for DTT tokamak with liquid metal divertor targets
No full textThe I-DTT tokamak has been analyzed by means of the integrated COREDIV code simulations when either Li or Sn are used as liquid divertor target materials. It has been found that power to divertor can be strongly mitigated with LMD. The reason is that the solution is determined by the LM divertor properties, leading to the requirements that the heat load to the liquid target is reduced below a threshold value. The threshold is due to the limits to the plasma contamination by the evaporated material. In the case of Li target, the limit is set to ∼8 MW/m2 and is achieved by strong Li radiation in the divertor (vapor shielding). For Li, there is a low density limit and solution is only achievable if the plasma density is high enough. The low density operation might be recovered if Kr seeding is applied. For the tin liquid divertor, H-mode operation is possible with efficient reduction of the heat flux to the divertor (∼11 MW/m2) in the evaporation efficiency reduced mode of operation and with the separatrix density high enough. The heat load reduction can be even more efficient (∼2.5 MW/m2) in the regime with strong evaporation but in this case the H-mode operation might be a problem. It appears that Ne seeding can hardly solve the H-mode operation problem but Li seeding seems to be better solution. The operation with higher edge plasma densities alleviates difficulties with the H-mode operation of liquid tin divertor
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
Perspectives for the liquid lithium and tin targets in the Italian Divertor Test Tokamak (I-DTT) divertor
No full textThe behaviour of the scrape-off plasma of the projected Italian tokamak I-DTT is analysed by means of the two-dimensional edge code TECXY for either Li or Sn as the liquid target material. A scan in the outer midplane separatrix density range n e,omp ≈ (0.5-1.1) × 1020 m-3 is carried out for several power inputs into the scrape-off layer (SOL) up to a maximum of P SOL = 35 MW. The radiative capability and peak load mitigation are higher for Sn than for Li, but only slightly so at high density, so that the entire density range can be explored with liquid Sn targets, unlike Li whose employment at low density and high power is questionable. However, if a ceiling to the Sn concentration is set for high core fusion performance, Sn mitigation at low density may drop below Li. Nonetheless, concerns about the Li option derive from the very large material consumption and from the fact that the main mechanism of impurity release is sputtering, which is outside the full control of the operator. Considering specifically the three main scenarios-low, medium and high density-at the maximum auxiliary power of 45 MW, operations are successful with Sn, whereas Li requires an additional impurity able to radiate in the core, except at the highest density. The snowflake plus configuration, compared with the standard single null, as a sample for advanced divertors, appears more suited to exploit the advantages of the liquid metal option. Concerning additional impurities, only Ar and Ne are considered at present. They can strongly help in reaching and studying deep detached conditions even at the maximum power, but are not essential for operations. Wide flexibility in designing the target refrigeration system is required to fully exploit its great potential
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
Comparison between liquid lithium and liquid tin targets in reactor relevant conditions for DEMO and I-DTT
No full textThe performance of divertor targets made of liquid metal, either lithium or tin, in highly powered tokamaks is analyzed for the proposed European DEMO and the projected Italian divertor test tokamak (I-DTT). The main tool is the 2D edge code TECXY, together with COREDIV. The results show that both materials are compatible with either DEMO or I-DTT under proper setting of the liquid divertor parameters. In general, operation at a high density is always highly recommended especially if detached conditions are desired. The latter can always be closely approached even when preserving an acceptable plasma purity with a proper setting of the target parameters and with the help of an additional impurity, which is able to radiate significantly inside the scrape-off layer plasma. For this action, Ar is preferred over Ne. Tin usually performs better than lithium for mitigation properties, reducing plasma pollution, material consumption, which in a DEMO-like device could be very high, and a definitely lower chemical affinity to hydrogen
A comparative study of the effects of liquid lithium and tin as DEMO divertor targets on the heat loads and SOL properties
No full textDispelling 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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