1,721,164 research outputs found
Dehydration, rehydration with reconstruction of oxide surfaces exposed to high temperatures
No full textThe paper reports results relative to the effects introduced, to the conditions of the surface of ZrO2 samples, by treatments at 800°C.The interfacial electrostatic behaviour of the samples soon after preparation, shows several peculiarities, a point of zero charge at pH 8.2 and the presence of some degree of surface heterogeneity. The pattern presented, however, by the aged powder(one year), is markedly different with regular trends and a point of zero charge at pH = 6.8. It is suggested that the calcination step at 800°C determines removal, at least in part, of the water chemisorbed at the surface. During the long aging the powder undergoes re-hydration with a reconstruction of a hydrous surface layer of Zr(OH)4 which shields entirely the former ZrO2 surface and imposes on the system the behaviour of bulk Z r(OH)4 phases
A Study on the Electromagnetic Backscattering from Wind-Roughened Water Surfaces
No full textIn this paper we report the results of a study regarding the backscattering from wind-roughened water surfaces. The reference profile data has been deducted by an experiment held at the University of Heidelberg circular wave tank facility. The scattering theory is based on a fractal description of the surface and a combined use of the Kirchhoff approximation and the small perturbation method (SPM). The scattering results are tested versus the ones obtained via the periodic-surface moment method. The study shows the reliability of the novel approach
On the Inversion of Wind Scatterometer Incomplete Data Sets
No full textERS-1/2 wind scatterometers (WSC) data sets may contain
cells in which two, instead of three, measurements are available. These
data sets are called incomplete. Operational inversion procedures discard
such data sets and therefore no wind field is estimated. This is very limiting
in semi-closed seas such as the Mediterranean Sea. In this paper we
propose a new inversion procedure capable to retrieving near surface wind
fields from incomplete data sets. This procedure is an enhancement of an
algorithm already proposed and tested by the authors. A set of comprehensive
experiments are presented and discussed. It is shown that the inversion
procedure gets to remarkable results even in presence of a large number of
doublets
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
On the Inversion of Wind Scatterometer Data
No full textThe scatterometer is a real aperture radar capable to perform a set of normalized radar cross section measurements under different azimuth angles for each resolution cell. The main field of application of a wind scatterometer regards the sea surface wind field determination. As a matter of fact, once such measurements have been performed it is possible to determine the sea surface wind field by means of an inversion procedure. In this paper we present a novel inversion scheme which is an evolution of the procedure nowday used by the Italian Space Agency (ASI) under the Italian Processing and Archiving Facility (I-PAF). A full comparative study shows that the novel inversion scheme better behaves whenever light wind regimes are in question
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