1,720,980 research outputs found
Thiophene hydrodesulfurization using unsupported nickel-neodymium bimetal catalysts
No full textThe hydrodesulfurization of thiophene was studied over unsupported nickel-neodymium bimetallic catalysts. The physical and chemical changes of bimetals were observed after calcination and presulfidation, respectively. The activity was increased with addition of neodymium to nickel catalysts and was in good correlation with the surface area of catalysts. Qualitative evidence from XRD and SEM on the role of Nd as a structural promoter were provided
Characteristics of intermetallic NdNi5 as an unsupported catalyst in thiophene hydrodesulfurization
No full textA systematic research is carried out on intermetallic NdNi5 for the hydrodesulfurization (HDS) of thiophene. The effect of calcination and presulfidation of intermetallic NdNi5 on thiophene HDS was examined and property changes of the catalyst during calcination, presulfidation, and reaction were observed by XRD, SEM, and surface area techniques. The intermetallic compound of NdNi5 is disintegrated to fine powder and recrystallized to Nd/Ni oxide and sulfide by calcination, presulfidation, and reaction. A model for the surface area increase of the catalyst during calcination, presulfidation, and reaction was proposed and the role of neodymium was explained
Long-term strength prediction of concrete with curing temperature
No full textThis paper describes a new strength time temperature prediction equation, which utilizes curing temperatures to improve the accuracy of estimates of long-term strength. To develop the model equation, existing data reported in the literature were collected and used. The data were converted into a relative strength ratio based on the strength at 28 days for 8 average curing temperatures in a range of -0.6 similar to 59.7 degrees C. The effect of the diffusion shell, which happens during cement hydration, on the long-term strength as a function of the curing temperature was considered using the rate constant model. Temperature influence factors such as rate constant, limiting strength, and reaction coefficient, which are functions of curing temperature, were incorporated in the new equation. Verification of the proposed model was performed by regression analysis. The results of regression analyses showed that the proposed model has higher reliability than existing model equations. The proposed model has higher accuracy at long-term ages the difference with existing models at an early age is not significant. (c) 2005 Elsevier Ltd. All rights reserved
CORRELATION OF HDS ACTIVITY WITH HEAT OF ADSORPTION OVER CARBON-SUPPORTED COMO CATALYSTS
No full textTemperature-programmed desorption (TPD) was carried out over the typical carbon-supported CoMo catalysts, and heat' of adsorption for each of thiophene and hydrogensulfide was obtained from the TPD spectra with different heating rate. The activity for hydrodesulfurization (HDS) of thiophene was measured in a microflow reactor at atmospheric pressure and 325-degrees-C. It was demonstrated that the HDS activity was well correlated with the difference in heat of adsorption between thiophene and hydrogensulfide
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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