1,720,989 research outputs found
Thermodynamic modeling of the phase behavior of binary systems of ionic liquids and carbon dioxide with the group contribution equation of state
Full text linkThe group contribution equation of state (GC-EOS) was applied to predict the phase behavior of binary systems of ionic liquids of the homologous families 1-alkyl-3-methylimidazolium hexafluorophosphate and tetrafluoroborate with CO2. Pure group parameters for the new ionic liquid functional groups [-mim] [PF6] and [-mim] [BF4] and interaction parameters between these groups and the paraffin (CH3, CH2) and CO2 groups were estimated. The GC-EOS extended with the new parameters was applied to predict high-pressure phase equilibria in binary mixtures of the ionic liquids [emim][PF6], [bmim][PF6], [hmim][PF6], [bmim][BF4], [hmim][BF4], and [omim][BF4] with CO2. The agreement between experimental and predicted bubble point data for the ionic liquids was excellent for pressures up to 20 MPa, and even for pressures up to about 100 MPa, the agreement was good. The results show the capability of the GC-EOS to describe phase equilibria of systems consisting of ionic liquids. © 2007 American Chemical Society.Fil: Breure, Bianca. Delft University of Technology; Países BajosFil: Bottini, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Witkamp, Geert-Jan. Delft University of Technology; Países BajosFil: Peters, Cor J.. Delft University of Technology; Países Bajo
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
Measurement of the phase behavior of the ternary system carbon dioxide + acetone + phenanthrene
Full text linkAs a representative model system for the gas-anti-solvent (GAS) process, the phase behavior of the ternary system carbon dioxide + acetone + phenanthrene has been studied experimentally. Carbon dioxide was chosen as the gaseous anti-solvent, acetone was chosen as the organic solvent, and phenanthrene was chosen as the model solute. In each experiment, a solution of phenanthrene in acetone was expanded using carbon dioxide as the anti-solvent. A synthetic method was used for the measurements of the various phase boundaries. Three-phase equilibrium data solid (phenanthrene)-liquid-vapor were obtained from intersection of two-phase isopleths vapor-liquid and solid-liquid. For a variety of compositions, results are reported for this ternary system within temperature and pressure ranges of (295 to 350) K and (1.0 to12.5) MPa, respectively. As was established in a previous study on the system carbon dioxide + 2-propanol + salicylic acid, it turned out that also in the system carbon dioxide + acetone + phenanthrene the carbon dioxide concentration significantly affects the optimum operational conditions of the GAS process (i.e., at lower concentrations carbon dioxide acts as a co-solvent, while at higher concentrations it acts as an anti-solvent). Also, it is shown that at a certain temperature, it is possible to precipitate most of the dissolved solute within only a small pressure window.Fil: De La Fuente, Juan C.. Universidad Técnica Federico Santa María; ChileFil: Bottini, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahia Blanca. Planta Piloto de Ingeniería Química (I). Grupo Vinculado al Plapiqui - Investigación y Desarrollo en Tecnología Química; ArgentinaFil: Peters, Cor J.. Delft University of Technology; Países Bajo
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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