1,720,982 research outputs found
Modello matematico di flusso nei sistemi acquiferi del Veneto Centrale
Get PDFFor the last thirty-five years, the aquifer system of Central Veneto (Italy) has been involved by an increasing demand of water for domestic and private use and by a relevant reduction of groundwater heads. The regional groundwater model developed is a large scale model taking origins from detailed studies of the hydrogeological system. Its purpose is to provide boundary conditions for the study of flow and transport models at smaller scale and to predict the behaviour of the aquifers in conditions different from the present-day ones (changes in rainfall trend, rivers regime, soil use). The three-dimensional flow model of the aquifer systems is based on a large number of experimental data, concerning both groundwater balance (measured rain in pluviometric stations, water flux dispersed by rivers and irrigation channels, water flux springing out of the springs, water withdrawal from a large number of private and public wells) and hydraulic permeability of aquifers. A three-dimensional geological model of the system has been created by means of geological sections and stratigraphies. The flow simulations are performed using a tetrahedral finite element code. The model is calibrated on the basis of real piezometric heads and is used to analyze the interaction between the unconfined aquifer, located in the northern part of the study area, and the multiaquifer system that originates in this area and proceeds towards the sea.
The model simulates reasonably well the water flow aquifers system of Central Veneto and permits to simulate the effects of changes in withdrawal policies and/or boundary conditions relevant to the complex aquifer system. The model will allow the establishment of causal relationships between withdrawal of water (whatever the production layer, and the extracted flow rates) and the fluctuations of piezometric heads anywhere in the system. We have investigated the robustness of the model towards variations of the geological model and towards variations of the hydraulic permeability of aquifers and low permeability lenses. The implemented 3D flow model has allowed to improve the understanding of the regional groundwater system and of its hydrogeological properties. The model permits to predict the response of the system to overpumping, fluctuations in recharges, relevant land use changes, new public derivations: so it is deemed of central importance for the management of water resources in the area
Alternative conceptual models and the robustness of groundwater management scenarios in the multi-aquifer system of the Central Veneto Basin, Italy
No full textA three-dimensional (3D) groundwater flow model of the deep multi-aquifer Quaternary deposits of the Po plain sedimentary basin, within a 3,300-km(2) area (Veneto, Italy), is developed, tested and applied to aid sustainable large-scale water-resources management. Integrated mathematical modelling proves significantly successful, owing to an unusual wealth of available geological, geophysical, and hydrologic data and to state-of-the-art numerical tools. Of particular interest is the evaluation of the influence of alternative conceptual models; that is, of reconstructed representations of the 3D geological model of the structure of the aquifers. The reference conceptual model is set up by means of extended geological sections and stratigraphic records, and is used to create a large, unstructured 3D finite element grid. By analyzing the effects on piezometric surfaces and on the overall water budget of geometrical perturbations from the reference structure, alternative geo-structural models, obtained by systematically shifting the pinch-out of the aquitards, are compared. Interestingly, the impacts of aquitard pinch-out prove far from negligible. The results suggest the critical importance of reliable geological models even for large, complex 3D models. The good practice of iteratively testing numerically the impact of surprises on the conceptual model, as more field information is collected, is thus supported
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
Implementazione di un sistema di previsione per la gestione delle piene in tempo reale: il Bacchiglione nel Vicentino
Get PDFDispelling 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
Modellazione idrologica del bacino idrografico del torrente Leogra
Get PDFLa presente tesi ha come scopo lo sviluppo e la taratura di un modello idrologico per la previsione degli eventi di piena del torrente Leogra. L'importanza del lavoro è connessa al ruolo fondamentale che il torrente ha nella formazione delle piene del fiume Bacchiglione a Vicenzaope
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