1,720,959 research outputs found
Studio numerico parametrico dell’influenza di fattori ambientali, geostrutturali e geomeccanici sulla stabilità di falesie in rocce tenere
No full textLa stabilità precaria delle falesie rocciose genera spesso condizioni di pericolosità elevata lungo le coste con il coinvolgimento di strutture ed infrastrutture ubicate in sommità e/o di utenti delle spiagge che si sviluppano al piede. In generale, detta stabilità dipende da vari fattori, quali: il comportamento fisico-meccanico della roccia costituente la falesia, la relativa suscettibilità ai processi di weathering, l’assetto geo-strutturale dell’ammasso o le azioni naturali ed antropiche che comportano modifiche della geometria e dei carichi agenti sulla falesia, per citarne alcuni
PORE NETWORK MODEL TO PREDICT FLOW PROCESSES IN UNSATURATED CALCARENITES
No full textThe knowledge of infiltration mechanisms in vadose zone is the key to forecast the components of the hydrologic cycle such as run-off generation and aquifer recharge. Besides, slope stability, settlements and bearing capacity of foundations, and rock weathering are issues in which infiltration processes play an important role. In Apulia and Basilicata (Southern Italy) representative calcarenites outcrops are exposed along both the coastline and internal areas. These calcarenites belong to the Calcarenite di Gravina Fm. (Middle Pliocene-Lower Pleistocene) and are mainly constituted by fine- medium- and coarse-grained packstones and grainstones. The whole geological formation represents an important hydrogeologic unit which controls groundwater recharge and transport of contaminants within a complex, multilayered system comprising a wide and deep aquifer hosted into the Mesozoic basement. A smart analytical and numerical tool based on the pore bundle model conceptualization and the Richards' equation was developed to predict infiltration and retention mechanism of calcarenites. This work investigated the impact of bimodal poresize distribution on the unsaturated flow from dry to wet conditions obtained through conventional and unconventional laboratory tests and petrophysical characterization, also completed with mercury intrusion porosimetry and image analysis. Laboratory experiments were carried out on medium-grained grainstones sampled at Canosa di Puglia (Tufarelle locality), by means of infiltration tests conducted starting from a different degree of saturation and varying the inlet flow rate. The experimental data were compared with the pore network model prediction. For the rock samples used, the study disclosed that macroporosity mainly affects the propagation of the wetting front and infiltration rate. Thus, the wetting front develops principally during the infiltration of water through the interconnected macropores following the pathways having minimum flow resistance with a gravity driven flow velocity higher than the diffusive flow though micropores
An integrated approach to elaborate 3-D geological and geotechnical models: a case study from the Daunia Sub-Apennine (Apulia, southern Italy).
Full text linkIn the Daunia Sub-Apennine (Apulia, southern Italy) slope instability processes due to rainfalls and earthquakes are widespread and cause significant damage to buildings and other structures, and, in some cases, loss of life. A detailed slope stability assessment requires information on the predisposing and triggering factors, and a good knowledge of the geological and environmental conditions as well. As concerns seismic-induced landslides, conventional methods used for slope stability analysis can be divided in: i) force-based pseudo-static methods, ii) displacement-based methods, and iii) stress-strain methods. Detailed representations of geological and geotechnical units as well as static and dynamic geotechnical characterization of materials have to be considered for the correct choice of the method for slope stability analysis, since these are fundamental for slope behaviour prediction and modelling.
The purpose of this paper was to present a methodological approach for elaborating detailed 3-D geological and geotechnical models for areas very heterogeneous in terms of geological and soil properties. In the southern portion of the eastern Daunia Sub-Apennine, the outermost formations of the chain domain crop out. These are represented by the Cretaceous-Miocene and Pliocene wedge-top basin units, followed upwards, in the easternmost portion, by the Plio-Pleistocene foredeep units and by Quaternary filling deposits. A high susceptibility to slope failures for the area is testified by the large number of slope movements consisting in mud flows, roto-translational and composite landslides, and soil slips. Field variability of the slope movements from site to site for mechanisms, velocity, depth of rupture surfaces and volume of materials involved is due to the presence of structurally complex formations, characterised by very poor mechanical properties and high variability of their lithological and structural features. The construction of geological and geotechnical models able to represent realistic information is conditioned by the efficacy of the methods used for assessing the spatial lithofacies distribution and parametrization.
The case study of Deliceto is here presented, where the 3-D geological model was built based on the results of stratigraphic correlations between core logs and 2-D geological sections. In-situ surveys were performed by means of classical geological and geomorphological methods, and continuous coring boreholes. Silty-clayey sandstone materials (Conglomerates and Sandstones of Castello Schiavo) crop out along the slopes and rest on clayey silts and marls of turbidite origin (Flysch di Faeto). The Flysch di Faeto Fm. is a structurally complex geological unit which consists of three main lithofacies: 1) silty clays; 2) silty marly clays 3) marls and shales. A series of geotechnical laboratory tests, carried out in accordance with international standards for the static and dynamic characterization of materials, made it possible to obtain a detailed 3-D geotechnical model. In particular, resonant column (RC), cyclic torsional shear (CTS) and standard and cyclic triaxial (TXC) tests were performed on the silty clayey geotechnical unit of the Flysch di Faeto Fm., because it is highly susceptible to geotechnical fatigue resulting from cyclic stresses. The results of the laboratory tests confirmed a variable post-cyclic degradation in the range 40-80% and 12-36%, respectively for the secant shear modulus (G) and the undrained cohesion (cu) associated with an increase between 2.92% and 19.90% for the damping ratio (D), demonstrating the heterogeneity of the material in terms of geological and geotechnical characteristics
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
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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