1,721,037 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
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
Mineralogical and chemical variations in a sulphide waste-rock dump (Libiola mine, Liguria)
No full textWith this work we have studied the mineralogical, chemical, and NAPP (Net Acid Producing Potential) variations occurring on a 3.5 ha sulphide waste-rock dump built over a period of about 100 years by the dumping, in a vertical sequence, of both non-valuable mineralisations and non-mineralised rocks coming from underground and open-pit excavations. This dump, as well as the overall Libiola mine area, is characterised by active AMD (Acid Mine Drainage) processes triggered by the diffuse oxidation of sulphide minerals [1 and references therein]. Twenty-one sampling sites were choosed by defining a grid throughout the overall dump surface and the sampling points were selected within every cell where well-exposed vertical cuts occur. Qualitative and quantitative mineralogical analyses were performed by transmitted- and reflected-light optical microscopy and by SEM-EDS. Bulk chemistry was assessed by ICP-AES and XRF analyses whereas the NAPP evaluation was based on the "AMIRA P387A" procedure [2].
The studied samples are generally incoherent or weakly cemented by iron-oxide and -oxyhydroxides and vary from gravel-dominated to sandy-gravel sediments with a uniform particle size distribution in the range 2-64 mm. They are composed by variable amount (10-26 wt %) of sulphide mineralisation fragments (pyrite chalcopyrite sphalerite) showing various degree of oxidation. Mafic and ultramafic clasts (basalt, serpentinite and ophiolitic breccias) vary from 35 to 80 wt% and they are generally unaltered (serpentinite) or weakly altered. Secondary minerals are almost exclusively represented by Fe-oxyhydroxides (goethite) and -oxides (hematite) and they occur as cement filling interclast voids, homogeneous crusts (hardpan layers), and pseudomorphic replacement of sulphide mineralisation. They vary from 10 to 50 wt % and their abundance is strictly correlated to the sulphide content of the sample.
The bulk chemistry (major, minor, and trace elements) appears to be controlled either by the primary unaltered minerals and by the different alteration products. In fact, as evidenced by several authors [3 and references therein], Fe-oxydes and -oxyhydroxides have a good affinity for several transition- and heavy-metals, that they effectively scavenge by the circulating solutions. The distribution of metals of environmental concern on the waste dump has been further plotted on contour maps. These statistical interpolations allow to evidence significant spatial variations throughout the dump that reflect either the composition of the dumped materials and the evolutive stage of the AMD processes.
With the exception of few sites, all sampling points evidenced positive NAPP values which mean that AMD processes are still active and presumably should persist for long time, due to the high sulphide contents and to the complete absence of potentially neutralising mineral phases
Un modello semplificato ai valori medi del processo di combustione per la simulazione dei Sistemi Energetici.
No full text
Effetti d’onda nei motori turbodiesel. La velocità di modelli 0-D assieme all’accuratezza dei modelli 1-D
No full textMean Value Modeling of intake and exhaust systems of automotive engines: models identification and related errors
No full textControl and management issues are playing an important role in automotive applications to improve engine and powertrain performance and to lower specific fuel consumption and pollutant emissions. Mean Value Engine Models (MVEM) based on “grey-box” or faster “black-box” algorithms are usually adopted for control applications since they allow for real-time simulation of actual automotive engines. However, “grey“ or “black-box” models usually requires a significant amount of data (usually
from experimental investigations) for the identification of sub-models of each component: these data are often not available with the same degree of accuracy and, moreover, are usually gathered in operating conditions that are far from real on-engine
conditions.
In the paper a brief description of the identification procedures for MVMs of intake and exhaust systems developed by the authors is given. Uncertainties and shifts that affect results given by MVMs is analysed with reference to the accuracy of the identification procedure. To this extent a MVM of an actual turbocharged engine was used to analyse the effects on calculated outputs of defined shifts introduced in the identification parameters of intake/exhaust systems sub-models (with particular reference to
sub-models of compressor, turbine and EGR valves). Obtained results are reported in the paper to point out what sub-models have major effects on MVMs outputs and to study the degree of accuracy needed for their identification
The crystal structure of heulandite-Sr from Campegli (Liguria, Italy)
No full textThe crystal structure of heulandite-Sr, a natural zeolite from Campegli (Liguria), was refined in the Cm
space group. The average chemical analysis [1] is Ca2.20Sr1.90Ba0.10Na0.53K0.29 [Al9.35Si26.68O72]19.74H2O.
Six sites for the extra-framework cations were found, two of which, Ca2A and Ca2, related by symmetry
in the C2 and C2/m space group, show a very high difference in their occupancy factors. (An A is added to
the name of atoms related by symmetry in the C2/m space group). As the topological symmetry is C2/m,
the lowering of the symmetry is related to the order of the extra-framework cations, induced by the Si/Al
order in the tetrahedral (T and TA) sites. T and TA sites are not equivalents: their Al contents are in the
order T2A > T1A > T4A = T2. It is interesting to note that T2A and T2 have the maximum Al values of the
two groups. Sr1 and Sr1A are occupied by strontium, Ca2A and Ca2 by calcium, while K, Ba and perhaps
Na are in the K3 and K3A sites. Heulandite-Sr was compared with Sr-exchanged heulandite in Döbelin
and Armbruster [2] (Cm space group) and with heulandite-Ba published by Larsen et al. [3] (C2/m space
group). The reduction of symmetry in our heulandite and in the Sr-exchanged form is related to greater
order in the Si/Al distribution, which is confirmed by the higher value of the ‘‘S” order coefficient introduced
by Alberti [4].
2010 Elsevier Inc. All rights reserved
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