1,721,044 research outputs found
Numerical simulation of the Fontainebleau Sandstones cementation
No full textThiry Médard, Maréchal Benoit, Goblet Patrick, Ledoux Emmanuel. Numerical simulation of the Fontainebleau Sandstones cementation. In: Transferts dans les systèmes sédimentaires : de l'échelle du pore à celle du bassin. Réunion spécialisée SGF-TRABAS/CNRS, Paris 27-28 septembre 1999. Résumés. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1999. pp. 139-142. (Sciences Géologiques. Mémoire, 99
Rapport III.16. Modélisation non linéaire des écoulements et de la compaction dans le système aquifère de Mexico
No full textLe bilan en eau dans la vallée de Mexico était en équilibre jusqu’au début des années trente, la recharge naturelle, d’environ 8 m3/s pour une surface de 1500 km2, alimentait encore quelques sources à l’ouest et l’exploitation d’eau souterraine représentait moins de 1%. En 1980, la pression de l’eau avait diminué sous l’effet d’un pompage excessif qui dépassait la recharge naturelle de plus de 260%. Ceci a eu pour conséquence une compaction des aquitards avec un tassement total du sol d’environ 6,5 m dans la zone centrale de la ville.
Pour cette étude, un logiciel a été développé en partant du modèle NEWSAM élaboré au Centre d’informatique Géologique. Le modèle a été modifié pour simuler la compaction non-linéaire des aquitards résultant des variations de la pression de l’eau dans un système aquifère hétérogène en exploitation à l’échelle régionale.
L’application du modèle au cas de la ville de Mexico a permis d’analyser quantitativement : 1) le bilan en eau du bassin, 2) la subsidence totale due à l’exploitation. Le régime permanent du système (avant 1930) est simulé en prenant en compte le bilan en eau dans le bassin et sert ensuite de condition initiale à la simulation de la période d’exploitation 1930-1986. Le calage du modèle en régime transitoire est effectué sur les deux variables : charge hydraulique et subsidence observées.Rivera Alfonso, Ledoux Emmanuel. Rapport III.16. Modélisation non linéaire des écoulements et de la compaction dans le système aquifère de Mexico. In: Les eaux souterraines et la gestion des eaux. Progrès - qualité - quantité. Vingt et unièmes journées de l'hydraulique. Sophia-Antipolis, 29-31 janvier1991. Tome 3, 1991
Rapport IV.6. Évolution à long terme de la qualité des eaux souterraines dans un bassin hydrogéologique, provoquée par l’activité humaine
No full textIn large sedimentary basins with multilayered aquifers, the total dissolved salts content of the water of each layer varies with depth, and with the mecanism of recharge. Modifications of the natural conditions, due to pumping, may, in the long run, change this salt content of groundwater. In arid zones, also, the high evaporation rates may lead to a rapid salt buid-up of the water-table aquifer, and a progressive contamination of the deeper aquifers.
A digital model is given which offers an approximate solution of the transport equations in multilayered aquifers, and which is applied to a case study.Dans les aquifères sédimentaires multicouches, la salinité des eaux des différents horizons varie en fonction de leur profondeur et de leur condition d’alimentation.
Les perturbations apportées aux équilibres naturels par les exploitations peuvent modifier à long terme cette salinité des eaux souterraines. En pays aride enfin, les fortes évaporations peuvent conduire à une rapide salinisation des nappes phréatiques et à une contamination progressive des nappes profondes.
Un modèle mathématique de résolution approchée des équations du transport en aquifères multicouches est présenté, avec une application à un problème réel.Besbes Mustapha, Ledoux Emmanuel, Levassor A., Marsily Ghislain de. Rapport IV.6. Évolution à long terme de la qualité des eaux souterraines dans un bassin hydrogéologique, provoquée par l’activité humaine. In: La mécanique des fluides et l'environnement. Prévision et maîtrise de la qualité de l'eau et de l'air. Compte rendu des quatorzièmes journées de l'hydraulique. Paris, 7-9 septembre 1976. Tome 2, 1977
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
