1,720,958 research outputs found
Three state lattice-gas model for two-component gas adsorption in solids
No full textA molecular field method is used to study a spin-one Ising (lattice-gas) model appropriate for the multilayer adsorption of a two-component gas. The model is used in its simplest form to discribe the phase transition and coadsorption isotherms of the mixture. We found that the phase transition occurs in a narrow interval of the total coverage. The adsorption isotherms depend on the chemical potentials of both components and on the temperature. The density profiles of both components are also presented
Hydrogen desorption from magnesium hydride - graphite nanocomposites produced by ball milling
No full textAbstract
Magnesium hydride–graphite composites produced via ball milling exhibit fast H2 desorption/absorption kinetics; moreover, their activation behaviour is particularly attractive if compared with MgH2-based materials obtained so far. In this work, we report the phase analysis (by X-ray diffraction) and investigate the crystal structure and the desorption behaviour (using a home-made Sievert apparatus) of MgH2–graphite composites produced by ball milling. Milling with graphite is found to improve the desorption rate of MgH2 changing the reaction mechanism
Coadsorption isotherms of multilayer adsorbates with lateral interactions
No full textAbstract
Multilayer lattice–gas model which accounts for lateral interactions between adsorbed molecules is used in the frame of the mean field approach to describe coadsorption phenomena and phase transition in multilayered lattice. The differential ratio which measure the strength of the adsorption is represented. We find that the phase transition occurs at high enough attractive interactions between adsorbed species and the shape of the isotherms depends strongly on the chemical potential of both components and on the strength of the lateral interactions
Idruri metallici nanocristallini per immagazzinamento di idrogeno: compositi a base Mg prodotti tramite macinazione ad alta energia di polveri
No full text(Articolo su invito
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
- …
