1,720,958 research outputs found
Water infiltration in unsaturated calcarenites
No full textIn Puglia e Basilicata (Sud Italia) affiorano estesi depositi calcarenitici, a grana variabile da fine a grossa, appartenenti alla formazione della Calcarenite di Gravina (Pliocene-Pleistocene inferiore), depositi che fanno parte dei sistemi idrogeologici superficiali Apulo e Lucano. Si tratta di rocce tenere e porose, solo a luoghi ben cementate, il cui comportamento idraulico è fortemente condizionato dal fabric. Nell'unità calcarenitica i processi di infiltrazione avvengono principalmente attraverso una porosità primaria aperta, costituita da vuoti intergranulari, intragranulari e da impronta; più raro è il contributo di una porosità secondaria determinata dalla presenza di fratture e di condotti carsici, a loro volta ampliati da processi di dissoluzione. Nel complesso, le calcareniti sono caratterizzate da porosità e permeabilità alte, per cui la valutazione del tasso di infiltrazione d'acqua in zona vadosa assume importanza fondamentale per la stima della potenzialità di ricarica della falda superficiale e l'analisi dei meccanismi di migrazione di inquinanti nell'acquifero. In questo lavoro sono presentati i risultati di uno studio sulla infiltrazione in calcareniti insature combinando dati petrofisici di laboratorio e misure in situ ottenute attraverso test infiltrometrici con anello singolo e tomografie di resistività elettrica 3D (ERT) in modalità time-lapse
A Geostatistical Approach to Estimate Soil Moisture as a Function of Geophysical Data and Soil Attributes
No full textSuccessful implementation of site-specific irrigation requires an understanding of within-field-variability of soil parameters. These parameters can be estimated by direct sampling or by indirect surveying using geophysical data. The geophysical outputs are quite sensitive to soil water content; therefore, they can be used as covariates in soil water content (SWC) estimation.
The objectives of this study were to use geophysical and soil data as auxiliary variables in the estimation of soil water content through geostatistical techniques.
The surveys were carried out in a test site at the agricultural experimental farm located in south-eastern Italy in dry and wet soil conditions. The plot was surveyed with an EMI sensor and two different mono-static GPR systems, one with central frequencies of 600/1600 MHz and the other with a central frequency of 250 MHz. Forty-eight soil cores were collected for laboratory analysis of textural properties. One hundred and sixteen soil samples up to 0.30m-depth were collected to measure the SWC with gravimetric method. Kriging with external drift (KED), a non-stationary geostatistical technique, was used to estimate SWC with EMI, GPR and soil data as covariates. Cross-validation test was used to assess the goodness of the estimates and compare KED with ordinary kriging.
The results showed that the approach using the auxiliary variables can be preferred to univariate kriging in terms of correlation between true and estimated values and capability of interpretation of spatial variability. Kriging with external drift proved to be a valid tool in sensor data fusion and could be effectively applied in Precision Irrigatio
Ground penetrating radar survey of a prehistoric site in southern Italy
No full textIn this paper, we present and discuss the results of a ground penetrating radar (GPR) study carried out in an area of southern Italy where a karst cave with prehistoric remains was found. The aim of the study involved the imaging of the subsurface stratigraphy, both inside and outside the cave, in order to assist archaeologists in an excavation programme.
The survey grid comprised 18 intersecting GPR profiles. Problems associated with the use of the GPR within a cave environment are highlighted and the data processing sequence designed to extract useful geo-archaeological signatures is described. Interpretation of the radar sections was controlled by the excavation of two trenches (inside and outside the cave), allowing detailed outlining the complex stratigraphy and the reconstruction of Palaeolithic and Neolithic subsurface horizons
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
A Combined Approach of Sensor Data Fusion and Multivariate Geostatistics for Delineation of Homogeneous Zones in an Agricultural Field
No full textTo assess spatial variability at the very fine scale required by Precision Agriculture, different proximal and remote sensors have been used. They provide large amounts and different types of data which need to be combined. An integrated approach, using multivariate geostatistical data-fusion techniques and multi-source geophysical sensor data to determine simple summary scale-dependent indices, is described here. These indices can be used to delineate management zones to be submitted to differential management. Such a data fusion approach with geophysical sensors was applied in a soil of an agronomic field cropped with tomato. The synthetic regionalized factors determined, contributed to split the 3D edaphic environment into two main horizontal structures with different hydraulic properties and to disclose two main horizons in the 0–1.0-m depth with a discontinuity probably occurring between 0.40 m and 0.70 m. Comparing this partition with the soil properties measured with a shallow sampling, it was possible to verify the coherence in the topsoil between the dielectric properties and other properties more directly related to agronomic management. These results confirm the advantages of using proximal sensing as a preliminary step in the application of site-specific management. Combining disparate spatial data (data fusion) is not at all a naive problem and novel and powerful methods need to be developed
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
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