1,720,973 research outputs found
A fracture mechanics-based approach to study bowing effect in marble facades
No full textMarble façade panels tend to exhibit bowing deflections even after a short time of exposure to environmental actions. In particular, under cyclic thermal action irreversible deformations accumulate due to a progressive decohesion of the calcite grains. In the present paper, a theoretical model, combining continuous mechanics principle and fracture mechanics tools, is presented to calculate the maximum bowing of the slab and its fatigue life under a given temperature time history. The model is applied to the case study of the court building of Pescara (Italy) to estimate the bowing deflection in the marble slabs due to thermal actions
Additional insights to EC7 from the application of reliability-based design methods: the case of debris flow protection structures
Full text linkDebris flows are dangerous natural processes that cause extensive damages to infrastructures and urbanized areas and can lead to loss of human lives. Their unpredictability, their extremely high motion and their magnitude are the main causes of these harms. Mitigation measures are fundamental for reducing the associated risk and protecting infrastructures in mountainous areas. Their design is still an open issue: there are many formulations to evaluating impact pressure. Moreover, the uncertainties in the determination of flow characteristics (velocity and thickness) are significantly high and difficult to quantify. In the European Union, the design of any type of structures involved in rock mechanics field must comply with EN-1997 Geotechnical Design (CEN 2004) (EC7). For debris flow countermeasures, EC7 requirements are very difficult to apply in practice since partial safety factors are not provided for these phenomena. However, the basic philosophy of reliability-based design (RBD), as defined in EN1990 (CEN 2002) may be a suitable and complementary approach to provide geotechnical structures with a uniform probability of failure. Reliability Based Design (RBD) can provide additional insights to EC7 design and can be applied when partial factors have still to be proposed (by EC7) to cover uncertainties of less common parameters, as in case of debris flow countermeasures. This paper presents an analysis of the advantages and limitations on the applicability of RBD approach to debris flow countermeasures, by using the first-order reliability method (FORM). In particular, data availability, the possibilities for analysing data in a statistical framework and the choice of performance function are the main limitation of the method, which force to make assumptions regarding statistical distribution of the considered parameters. A sensitivity analyses, comparing different equations, commonly used for debris flow impact pressure estimation, were performed for quantifying the effect of the selected performance function on the RBD results
In situ stress measurements interpretations in large underground marble quarry by 3D modeling
No full textThis paper describes the studies and the in situ stress measurements carried out to support the stability
analysis of underground ornamental stones quarries. In particular, this paper describes the findings,
evidence and analysis carried out at the Ravaccione and Fantiscritti quarries, which are located in the
Carrara basin, Italy. Themain activities carried out during the study are starting with the characterization of
the rock mass which has been done through the interpretation of data obtained from in situ geostructural
surveys, combining the geometrical and mechanical characteristics of the discontinuities with the
mechanical features of the rock matrix in order to assess the proper rock index in accordance with the
more diffused classification systems. Further consideration regarding the tectonic stress orientation are
done through the observation of kinematic indicators on brittle structures-such as faults, fractures s.l.
(joints s.s., and fractures with no evidence of movement) and systems of conjugated fractures, in order to
evaluate the tectonic stress main orientation for the studied area. Then several in situ measurements of
actual state of stress on various location inside the Ravaccione and Fantiscritti quarries where carried out
using CSIRO cells. This preliminary work lead to the geometric reconstruction of the rock mass, carried out
using the computer code Resoblocks. This phase allowed, once the current excavation geometry was given,
to define the geometry of a discontinuous rock mass model on which, thereafter, a numerical simulations
was carried out using the computer code 3DECs. At last, the comparison between the numerical model
results and the in situ tests allowed the back analysis of the site and lead to a most satisfying model
calibration to be used for the provisional analysis of further excavation development
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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