1,720,959 research outputs found
Tracer design for tracking thermal fronts in geothermal reservoirs
No full textThis paper describes the first steps in the design of new custom-made tracers for the investigation of thermal characteristics in deep geothermal reservoirs. Based on ester hydrolysis, the influences of different substituents on the reaction kinetics are studied in detail using the analog phenol acetates under the influence of varying pH and temperatures. Furthermore, a 2-ethylbutyl-2-naphthol-6-sulfonic ester is tested in laboratory experiments for its applicability as a practical thermo-sensitive tracer, considering also the influences of brine and rock matrix. The reaction is shown to be strongly thermo-sensitive while the reaction kinetics can be varied by two orders of magnitude by altering the sterical hindrance groups. These changes in the reaction kinetics are found to be predictable by using the results of this work. It has been found that the half-life can be decreased by the factor of three, if the reacting group is sterically hindered from one side and by the factor of ten, if the reacting group is hindered from both sides. Also mesomeric and inductive effects of substituents on the aromatic ring have significant effects on reaction rates. The pH-dependency on the reaction speed could be quantified and it is shown that the reaction complete alkaline catalyzed. Therefore, this reaction fulfills the many considerations of a tracer-test, such as varying absolute temperature, test durations, and temperature gradients. (C) 2012 Elsevier Ltd. All rights reserved
Nottebohm, Martin Gustav
No full text* 12.11.1817 Lüdenscheid/D, † 29.10.1882 Graz. Musikwissenschaftler und Komponist
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
Nottebohm, Martin Gustav
No full text* 12.11.1817 Lüdenscheid/D, † 29.10.1882 Graz. Musikwissenschaftler und Komponist
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
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