1,720,960 research outputs found
La Macro-Area: la pianura di Pisa
No full textIl management e la conoscenza delle aree di pianura
hanno assunto un ruolo di fondamentale importanza
perché intensamente antropizzate e sede di ingenti interessi
socio-economici. La gestione delle risorse idriche,
il monitoraggio dei fenomeni di subsidenza, la
tutela del patrimonio archeologico ed edilizio sono,
perciò elementi di crescente attenzione ma che non
possono prescindere anche da una conoscenza approfondita
dell’architettura stratigrafica del sottosuolo.
Il grado di attendibilità dei modelli di circolazione dei
fluidi, base indispensabile per una corretta ed efficace
gestione della risorsa idrica, è strettamente connesso
all’accuratezza della ricostruzione dell’architettura
sedimentaria del sottosuolo e, di conseguenza, ai
modelli interpretativi che mettono in relazione litofacies
ed ambienti deposizionali. Tali relazioni debbono
inoltre essere costrette all’interno di un quadro cronostratigrafico
che restituisca un’evoluzione stratigrafico
- deposizionale coerente sia in termini di spazio che
di tempo. Lo stesso grado di dettaglio è necessario
complemento nella ricerca archeologica per meglio
definire le caratteristiche ambientali nel quale un certo
sito si sviluppava, oppure per elaborare carte del potenziale
archeologico che sono di fondamentale importanza
per la redazione di piani strutturali efficaci.
Questi ultimi, infine, non possono non tenere conto
dei fenomeni di subsidenza, che sono facilmente contestualizzabili
e misurabili solo all’interno di un quadro
crono-stratigrafico e deposizionale del sottosuolo
ben definito, o di particolari depositi con caratteristiche
geotecniche peculiari (a Pisa è ben noto il “pancone”)
la cui distribuzione e spessore sono definibili
e prevedibili solo laddove siano disponibili modelli
affidabili dell’architettura deposizionale del sottosuolo.
Lo studio ad alta risoluzione delle successioni sedimentarie
tardo-quaternarie delle aree di pianura è,
inoltre, di fondamentale importanza per la verifica dei modelli della stratigrafia sequenziale che costituisce
l’approccio metodologico moderno utilizzato per la
ricerca di idrocarburi o di qualsiasi atro tipo di fluido.
Lo scarso grado o l’assenza di deformazione tettonica
che caratterizzano i depositi di queste aree e la possibilità
di effettuare datazioni assolute permette una
definizione di dettaglio, a scala di bacino, dei vari modelli
deposizionali e della loro evoluzione in funzione
di fattori di controllo, quali l’eustatismo o il clima. In
questo senso, la grande attenzione rivolta attualmente
al riscaldamento globale e alle possibili variazioni del
livello del mare ad esso connesse (IPCC, 2001, 2007,
ALLEY, 2003, NATIONAL RESEARCH iCOUNCILNRC,
2002), trova un importante riferimento in questi
sistemi deposizionali, il cui studio e modellizzazione
potrebbero consentire una finestra di osservazione più
ampia per la previsione degli scenari futuri legati ai
cambiamenti climatici in atto.
La possibilità di studiare nel dettaglio la stratigrafia di
sottosuolo e di ricostruirne in modo corretto l’architettura
deposizionale, non può però prescindere dalla
realizzazione di sondaggi a carotaggio continuo, unico
strumento di osservazione diretta del sottosuolo, e
dall’utilizzo di un approccio di tipo multidisciplinare
al loro studio
Ricostruzione dell’architettura deposizionale dei depositi tardo quaternari del sottosuolo della pianura di Pisa attraverso l’utilizzo di sistemi di modellazione 3d
No full textThe elevation net for the saltwater intrusion phenomenon analysis in the coastal plain of Pisa
Get PDFIn coastal plains, such as that of Pisa, with particular reference to groundwater, the marine intrusion phenomenon occurs not only through the freshwater/saltwater interface in the aquifer along the shore line, but also by the rise of the salt wedge in watercourses, in case they are in hydraulic connection with the aquifer itself.
The depth of the interface is primarily regulated by the hydrostatic freshwater/saltwater balance, that can be modified by anthropic exploitation of groundwater.
To date, seawater intrusion is considered one of the most extensive and important processes that degrade water quality through an increase in salinity levels up to values exceeding the standard for drinking water and irrigation systems, and endangering the future use of coastal waters.
Given the potential harmfulness of the phenomenon, in order to monitor its evolution, control wells are set up, within which it is possible to perform routine analysis aimed at measuring the characteristic parameters of the phenomenon itself.
The essential foundation to reconstruct the freshwater/saltwater interface, and therefore also for the recognition of the phenomenon of seawater intrusion, is represented by piezometric reconstructions integrated with hydrogeochemical information that can be obtained directly from measurements made in wells and indirectly through laboratory tests carried out on samples of water. A serious limitation of the piezometric reconstructions is mostly represented by the margin of approximation with which the height of water points has been established, which in turn result in uncertainty in the relationship between piezometric and hydrometric elevation. This paper presents various methodologies, GNSS and conventional, to determine piezometers elevation, also evaluating the accuracy obtainable and the requirements in terms of time, personnel and equipment
THE ACCURACY ANALYSIS OF LIDAR-DERIVED ELEVATION DATA FOR THE GEOMETRIC DESCRIPTION OF CROSS-SECTIONS OF A RIVERBED
Get PDFThe work stems from a joint study between the Laboratory ASTRO (Department of Civil and Industrial Engineering – University of Pisa), the municipality of Pisa and the province of Arezzo on the advanced analysis and use of digital elevation data. Besides, it is framed in the research carried on by ASTRO about the definition of the priority informative layers for emergency management in the territory, as of PRIN 2008. Specifically, this work is in continuity with other already published results concerning rigorous accuracy checks of LIDAR data and testing of the procedures to transform raw data in formats consistent with CTR and survey data. The analysis of sections of riverbed, derived from interpolation by DTMs featuring different grid density with those detected topographically, is presented. Validation by differential GNSS methodology of the DTMs used showed a good overall quality of the model for open, low-sloping areas. Analysis of the sections, however, has shown that the representation of small or high-sloping (ditches, embankments) morphological elements requires a high point density such as in laser scanner surveys, and a small mesh size of the grid. In addition, the correct representation of riverside structures is often hindered by the presence of thick vegetation and poor raw LIDAR data filtering
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
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