1,720,962 research outputs found
Influence of localized surface plasmon excitation in silver nanoparticles on the performance of silicon solar cells
No full textSilver nanoparticles have been fabricated on glass and silicon substrates, and silicon solar cells, by evaporation of 10 nm layers followed by thermal annealing. Distinct localized surface plasmon resonances are observed in the optical spectra of the annealed samples, and these strongly affect the cell reflectance and spectral response, both positively and negatively. At short wavelengths photocurrent is improved due to forward-scattering by quadrupolar modes, while at longer wavelengths photocurrent is deteriorated due to back-scattering by dipolar modes. Back-scattering is attributed to modification of the angular scattering distribution of the nanoparticles by the silicon substrate
Diamond coatings on tungsten carbide and their erosive wear properties
No full textDiamond coatings up to 60-?m thick have been grown by microwave plasma CVD (MPCVD) on sintered tungsten carbide (WC) substrates, and their erosive wear properties are investigated under high velocity air–sand erosion testing. Two different sintered tungsten carbide (WC) substrates have been investigated and compared, the binder being either 6% Co or 5% Ni by weight. Significant differences in morphology, residual stress, adhesion and erosion performance are seen as a function of pre-deposition treatment, deposition conditions and the source of the substrates. Adherent coatings could be deposited to a thickness of 35 ?m. They offer significantly better erosion resistance compared to uncoated substrates, with the erosion rate being lowered by up to a factor between 5 and 20 for particle test velocities of 148 and 63 m s?1, respectively. The steady-state erosion rates of the coatings are a function of a gradual micro-chipping mechanism. However, the life of the coating is dependent on the progression of sub-surface damage promoted by sub-surface shear stresses associated with the particle impacts. It is thought that the coating debonding is driven by the shear stresses interacting with the grain boundary porosity at th
Growth and erosive wear performance of diamond coatings on WC substrates
No full textAdherent diamond coatings up to ~30 ?m thick have been grown by microwave plasma CVD on WC substrates and their erosive wear properties investigated under high velocity air–sand erosion testing. Coating properties, particularly residual stress and adhesion, are sensitive functions of surface pre-treatment and deposition procedures. Adherent coatings offer significantly better erosion resistance compared to uncoated substrates, with the erosion rate being lower by up to a factor of ~5 based on the results obtained to date. Also films with low residual stress appear to exhibit longer lifetimes under testing. Failure tends to occur catastrophically along the coating–substrate interface. The grain boundaries do not appear to represent an easy route for crack propagation. Their strength appears to be comparable to that of the grains themselves
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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