1,721,003 research outputs found
Zeitschrift fur Geomorphologie (Borntraeger, Germania) (ISSN 0044-2798) (vol. 54, Suppl. 2, March 2010), “Pure and Applied Karst Geomorphology”
No full textDe Waele J., Plan. L., Filipponi M., Gutierrez F., Parise M., Guest-Editors of Zeitschrift fur Geomorphologie (Borntraeger, Germania) (ISSN 0044-2798) (vol. 54, Suppl. 2, March 2010), “Pure and Applied Karst Geomorphology”, 328 pages, 15 paper
An experimental comparison between methane and carbon dioxide hydrates formation: characterization of common aspects and differences between the two multiphase processes
No full textThe injection of CO2 in gas hydrate reservoirs has been intensively studied for its role in methane recovery and carbon dioxide storage. This study investigated the formation of methane and carbon dioxide hydrate in a smallscale experimental apparatus, which was well-suited for simulating natural gas hydrate reservoirs and intervening with replacement strategies. Four tests were conducted, equally divided between the two guest compounds under consideration. The process was considered as a first-order chemical kinetic equation for the time dependence and the hydrate formation rate was calculated according to it. In addition, studies were classified on the basis of the quantity
of hydrates generated and the gas inputs with considering the temperature trend and total time length. As expected, CO2 hydrate formation showed better kinetics during the first phase of tests, proving a more intense nucleation and rapid growth of crystals. After a certain time period, CH4 hydrate formation became more prominent, mainly due to the appearance of secondary nucleation sites, which were not observed in the presence of CO2. The results shown in this work explain why the CO2 replacement process usually of interest for only the most superficial layers; moreover, the explanation is not limited to the formation of a superficial CO2 hydrate shell, which prevents the flow of gaseous CO2 into deep layers. The results prove that the different kinetics of the process, depending of the guest compound, makes replacement extremely effective in the first period, while lowers it drastically on the second phase, due to the higher production of secondary nucleation sites in the presence of methane
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
On the cooling potential of retro reflective façades and pavement in urban canyons
No full textRetro-reflective (RR) materials represent an opportunity to reduce UHI phenomenon due to their ability to reflect most of the incident energy towards the same incoming direction. The optical properties of RR materials suggest that they could be effectively applied as coatings in order to reflect the solar radiation beyond the urban canyon.
The RR behaviour depends on the angular distribution of the incident energy: for small incident angle the radiation is reflected mainly backward in the incoming direction; for large angles RR materials reflect the radiation symmetrically with respect to the surface normal. To overtake the limit of RR materials of being mainly retroreflective only for small angles of incidence, the investigation is focused on the optic interaction between vertical and horizontal RR surfaces. Therefore, the aim of this paper is to investigate the synergic effect of RR pavements and façades on a physical model in which urban canyon layouts with H/D equal to 1 and 2 are represented. To evaluate the global cooling effect of RR pavements and façades, a new parameter, called equivalent albedo, is introduced and calculated over the canyon’s ceiling. The results show that a canyon with RR vertical surfaces and RR pavement reflects outward more radiation than a canyon with RR vertical surfaces and diffusive pavement due to the interaction of optical properties of the materials
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