1,720,968 research outputs found
Geomechanical analysis of unstable rock wedges by means of geostructural and infrared thermography surveys
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Relation between crack initiation-damage stress thresholds and failure strength of intact rock
No full textThe analysis of a wide literature dataset of mechanical parameters related to intact rocks from more than 480 unconfined compression tests, coupled with new laboratory tests on 132 specimens, is proposed herein with the aim of analyzing the mechanical behavior of a great variety of rock types, mainly focusing on their crack initiation (σci) and crack damage (σcd) stress levels. These thresholds can be employed as warning indicators for rock mass damage and breakouts and represent important input parameters for numerical models. International literature lacks in a detailed analysis on the mutual dependence existing between the main mechanical properties of intact rocks and their crack stress thresholds. In this paper, the study of the correlation between crack initiation-crack damage stress levels and the failure strength of sedimentary, metamorphic and igneous rocks is carried out through single and multiple regression approaches aimed at finding reliable prediction models, which can be useful when time-consuming laboratory experimental procedures need to be avoided. The correlation between predicted and measured values demonstrates that defined models represent a good tool for the empirical estimation of σci and σcd, and can be useful for preliminary engineering design dealing with stressinduced brittle fracturing, especially when the definition of warning indicators for rock mass damage and breakouts is needed. In fact, it is known that underground instability mainly depends on the redistribution of stresses around the excavation, which can produce induced stress concentrations, resulting in sudden release of stored energy and causing stress-induced brittle failure phenomena
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
Ground deformation monitoring using InSAR and meteorological time series and least-squares wavelet software. A case study in Catania, Italy
Full text linkPersistent Scatterers Interferometric Synthetic Aperture Radar (PS-InSAR) is an advanced satellite remote sensing technique which allows an effective monitoring of ground movement. In this work, PS-InSAR time series as well as precipitation and temperature time series in a region in Catania, Italy are utilized during 2018–2022, and their possible interconnections with land subsidence/uplift due to groundwater level change are investigated. First, the potential jumps in the displacement time series are removed, and then the Sequential Turning Point Detection (STPD) is applied to estimate the times when the velocity of the displacement time series changes. The results show a significant correlation between the frequency of turning points in displacement time series and precipitation trend change, particularly during the winter season. Furthermore, the Least-Squares Cross Wavelet Analysis (LSCWA) is applied to estimate the coherency and phase delay between the displacement and weather cycles in the time-frequency domain. The annual cycles of displacement and temperature show more coherency than the ones of displacement and precipitation across the study region. The results presented herein are important for infrastructure and water management planning
InfraRed Thermography proposed for the estimation of the Cooling Rate Index in the remote survey of rock masses
No full textLandslide Impact on Nature Reserves: First Results on the Multisensor Survey of Unstable Slopes in Protected Areas
No full textThis study is focused on the use of digital close -range remote surveying techniques for the identification and mapping of landslide phenomena along rock slopes in protected areas. This activity is part of a research project aimed at the digital analysis of slope models. The techniques compared herein are based on photographic and photogrammetric applications, carried out from both ground and aerial surveys, and on the use of infrared thermography in two test sites located within the Cinque Terre National Park (Liguria, Italy) and the "Timpa di Acireale" nature reserve (Sicily, Italy). The analysis of oblique aerial photographs allowed detecting key geomorphological indicators of past landslide movements and to carry out preliminary observations on unstable outcrops. The use of digital close -range sensors for the aerial photogrammetric survey allowed building a digital slope model to be analysed for the recognition and mapping of previous landslides. Moreover, key structural features, likely controlling the slope stability, were highlighted. Infrared thermography allowed detecting signs of landslides, providing the possibility of validating the photogrammetric data. In both protected areas, an almost zero level of environmental disturbance was guaranteed. Finally, both the potential and limitations of the techniques, used for the noninvasive morphological survey, are highlighted
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