1,720,960 research outputs found
GIS-based subsurfacedatabeses and 3-d geological modeling as a tool for the set up of hydrogeological framework: Nabeul Hammamet coastal aquifer case study (Nortgeast Tunisia)
No full textThe subsurface data are a basic requirement for the set up of hydrogeological framework. Geographic information systems (GIS) tools have proved their usefulness in hydrogeology over the years which allow for management, synthesis, and analysis of a great variety of subsurface data. However, standard multi-layered systems are quite limited for modeling, visualizing, and editing subsurface data and geologic objects and their attributes. This paper presents a methodology to support the implementation of hydrogeological framework of the multi-layered aquifer system in Nabeul-Hammamet (NH) coastal region (NE, Tunisia). The methodology consists of (1) the development of a complete and generally accepted hydrogeological classification system for NH aquifer system (2) the development of relational databases and subsequent GIS-based on geological, geophysical and hydrogeological data, and (3) the development of meaningful three-dimensional geological and aquifer models, using GIS subsurface software, RockWorks 2002. The generated 3-D geological models define the lithostratigraphy and the geometry of each depositional formation of the region and delineate major aquifers and aquitards. Where results of the lithologic model revealed that there is a wide range of hydraulic conductivities in the modeled area, which vary spatially and control the groundwater flow regime. As well, 17 texturally distinct stratigraphic units were identified and visualized in the stratigraphic model, while the developed aquifer model indicates that the NH aquifer system is composed of multi-reservoir aquifers subdivided in aquifers units and separated by sandy clay aquitards. Finally, this study provides information on the storing, management and modeling of subsurface spatial database. GIS has become a useful tool for hydrogeological conceptualization and groundwater management purposes and will provide necessary input databases within different groundwater numerical models
Salt Water Intrusion Characterisation in the Coastal Aquifer of Nabeul Hammamet Using Geophysical Methods.
No full textTime Domain Electromagnetic (TDEM) survey was carried out in the Mediterranean coast of Tunisia (Nabeul Hammamet), in order to delineate the salt water intrusion into coastal fresh water aquifer detected by drilling wells. The survey was also carried out to determine the geometry of the fresh water aquifer and to identify the continuity between the aquifer system of Nabeul-Hammamet and the bordering aquifer system on the northern side (coastal aquifer of Korba). One dimensional interpretation of the TDEM data was correlated to existing data of borehole Logs (Gamma Ray, Spontaneous Potential, Resistivity). The results indicate that TDEM survey was able to map the interface between fresh and salt water, and estimate depth of the basement when sitting new monitoring wells
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
Microstructure et granulométrie des dépôts turbiditiques de la retenue du barrage Sidi Salem (Tunisie)
No full textMicrostructure and grain-size of the turbidity deposits in the Sidi Salem reservoir (Tunisia). The densimetry-gamma recording, the grain-size and the microscopic analysis of modern sediment recovered from the Sidi Salem reservoir confirm the turbidity origin of these deposits. Some of those sequences were typical of turbidity deposits. The grain-size studies of the sequences and fauna contents show the evolution of dynamic sedimentation. Some results testify to the partial remobilisation of fine deposits by density current.Les enregistrements gamma-densimétriques des carottes de sédiments, les analyses granulométriques et les microstructures observées sur les lames minces d'échantillons de sédiments de la retenue du barrage Sidi Salem confirment l'origine turbiditique des dépôts. Certains cycles sont typiques de dépôts turbiditiques. L'étude fine des dépôts, notamment du point de vue granulométrique et de leur contenu faunis-tique, montre l'évolution des conditions de sédimentation.Ben Mammou A. Microstructure et granulométrie des dépôts turbiditiques de la retenue du barrage Sidi Salem (Tunisie). In: Géologie Méditerranéenne. Tome 23, numéro 1, 1996. pp. 63-75
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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