1,721,004 research outputs found
On the morphology of stain etched porous silicon films
No full textMorphology of stain-etched porous silicon films was investigated by a non-destructive technique, based on reflectance spectrometry: dielectric function profiles were computed by spectral reflectance via a finite difference model, and porosity was deduced by the effective medium approximation. Theoretical calculations were supported by high-resolution electron microscopy observations. The relations among oxidising species concentration in the etching solution, porosity profile and surface reflectance of the films were investigated
Towards the morphology control of stain etched porous silicon
No full textPorous silicon films, nearly 100 nm thick, were produced by stain etching of n(+)-type silicon substrates. The films were studied by a non-destructive technique: dielectric function profiles were deduced by spectral reflectance via a finite difference model, and porosity was computed by the Effective Medium Approximation. The obtained information, combined with High Resolution Electron Microscopy observations, provided a deeper insight on the relations among technological process, morphology and reflective properties. Our preliminary results outline the possibility to control the porosity profile as well the reflectance of the porous films via the oxidising species concentration in the stain etching solution
A PRELIMINARY STUDY OF PHYSICAL AND MECHANICAL PROPERTIES OF SUSTAINABLE HEMP FIBERS BASED COMPOSITE MATERIALS FOR BUILDING INSULATED WALLS
No full textThis work investigates the possibility of preparing new eco-sustainable hemp based composite materials by means of an agro-industrial production chain set up. The physical, mechanical and microstructural properties of the hemp composite materials were investigated. Moreover, thermal insulating conductivity measurements were performed, to assess the highly insulating characteristics of the composites. Correlations between the investigated properties were made.
The results show the effectiveness of a correct mix-design in improving the physical, mechanical and microstructural properties of the composites. Materials exhibit a good combination of thermal insulation, weight and mechanical strength
Spectrophotometric characterisation of homogeneous and inhomogeneous thin films for architectural glazing applications
No full textThin solid films deposited on glazings for buildings reduce the intensity and modify the spectral curve of solar radiation in order to obtain better comfort in the indoor environmento The daylight and energy behaviour of a fenestration with a coated glass sheet can be characterised even in nonmeasurable conditions provided that the coating structure (number of layers and thicknesses) and the material optical parameters (refractive index and absorption coefficient) are known. Suitable computer programs then allow
natural illuminance and solar irradiance in the room to be
predicted. The required optical parameters of the film can be determined by spectrophotometric measurements and data processing. This characterisation is not straightforward when the film deposited on the glass substrate shows a refractive index variation through its thickness. In this paper an approach for inhomogeneous thin films is presented together with some examples of the application of the coated glasses in architectural glazings
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
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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