Modello coesivo per l’avanzamento di fratture mediante rilascio nodale di strutture discretizzate con elementi finiti

La simulazione numerica della propagazione di una frattura in MODO I, viaggiante ad elevatavelocità in un acciaio a comportamento duttile è realizzata attraverso un modello coesivo che governa ladistribuzione delle forze di rilascio nodale. Come noto, la ricerca di un valore di tensione all’apice non ha alcunsenso nel caso elastico; infatti, la tensione può essere valutata solo mediante fattori di campo. Nel caso elasto-plastico, incrudimento e softening di origine geometrica o legato al progressivo danneggiamento influisconodecisamente sull’andamento esponenziale del campo tensionale. È possibile comunque individuare un valore diriferimento, di entità finita, mediante estrapolazione delle tensioni elasto-plastiche nella zona di inizio softeningdella frattura. Tale grandezza può essere presa come fattore di riferimento per il calcolo delle forze di rilasciocoesive e quindi dell’energia dissipata. Nel lavoro viene discusso come determinare, dal campo di tensioneelasto-plastico locale, il valore che governa la zona coesiva al variare del T-stress

Modello coesivo per l’avanzamento di fratture mediante rilascio nodale di strutture discretizzate con elementi finiti

La simulazione numerica della propagazione di una frattura in MODO I, viaggiante ad elevata velocità in un acciaio a comportamento duttile è realizzata attraverso un modello coesivo che governa la distribuzione delle forze di rilascio nodale. Come noto, la ricerca di un valore di tensione all’apice non ha alcun senso nel caso elastico; infatti, la tensione può essere valutata solo mediante fattori di campo. Nel caso elastoplastico, incrudimento e softening di origine geometrica o legato al progressivo danneggiamento influiscono decisamente sull’andamento esponenziale del campo tensionale. È possibile comunque individuare un valore di riferimento, di entità finita, mediante estrapolazione delle tensioni elasto-plastiche nella zona di inizio softening della frattura. Tale grandezza può essere presa come fattore di riferimento per il calcolo delle forze di rilascio coesive e quindi dell’energia dissipata. Nel lavoro viene discusso come determinare, dal campo di tensione elasto-plastico locale, il valore che governa la zona coesiva al variare del T-stres

Molecular analysis of a sunflower gene encoding an homologous of the B subunit of a CAAT binding factor

A genomic DNA fragment containing the complete LEAFY COTYLEDON1-LIKE (HaL1L) gene was retrieved by chromosome walking. Its sequence was confirmed and elongated by screening a sunflower genomic DNA BAC Library. HaL1L, whose cDNA had already been sequenced and characterized, encodes a NF-YB subunit of a CCAAT box-binding factor (NF-Y) involved in the early stages of zygotic and somatic embryogenesis in the Helianthus genus. In the HaL1L 50-flanking region, elements specific to a putative TATA-box promoter and two ‘‘CG isles’’ were identified. An investigation of the methylation status of these CG rich DNA regions showed that differentially methylated cytosines were recognizable in the DNA of embryos on the fifth day after pollination in comparison to leaf DNA suggesting that during plant development epigenetic regulation of HaL1L transcription was achieved by methylating cytosine residues. We also searched the HaL1L nucleotide sequence for cis-regulatory elements able to interact with other transcription factors (TFs) involved in the HaL1L regulation. Of the elements identified, one of the most intriguing is WUSATA, the target sequence for the WUSCHEL (WUS) TF, which may be part of a complex regulation network controlling embryo development. In this article, we show that the WUSATA target site, located in the intron of HaL1L, is able to bind the TF WUS. Interestingly, we found auxin and abscisic acid responsive motifs in the HaL1L promoter region suggesting that this gene may additionally by under hormonal control. Finally, the presence of a cytoplasmic polyadenylation signal downstream to the coding region indicates that this gene may also be controlled at the translation level by a temporarily making the pre-synthesized HaL1L mRNA unavailable for protein synthesis

Open-addressing hashing with unequal-probability keys

This paper describes the use of a drone in collecting data for mapping discontinuities within a marble quarry. A topographic survey was carried out in order to guarantee high spatial accuracy in the exterior orientation of images. Photos were taken close to the slopes and at different angles, depending on the orientation of the quarry walls. This approach was used to overcome the problem of shadow areas and to obtain detailed information on any feature desired. Dense three-dimensional (3D) point clouds obtained through image processing were used to rebuild the quarry geometry. Discontinuities were then mapped deterministically in detail. Joint attitude interpretation was not always possible due to the regular shape of the cut walls; for every discontinuity set we therefore also mapped the uncertainty. This, together with additional fracture characteristics, was used to build 3D discrete fracture network models. Preliminary results reveal the advantage of modern photogrammetric systems in producing detailed orthophotos; the latter allow accurate mapping in areas difficult to access (one of the main limitations of traditional techniques). The results highlight the benefits of integrating photogrammetric data with those collected through classical methods: the resulting knowledge of the site is crucially important in instability analyses involving numerical modelling.Part of the present study was undertaken within the framework of the Italian National Research Project PRIN2009, funded by the Ministry of Education, Universities and Research, which involves the collaboration between the University of Siena, ‘La Sapienza’ University of Rome, and USL1 of Massa and Carrara (Mining Engineering Operative Unit – Department of Prevention). The authors acknowledge M. Pellegri and D. Gullì (USL1, Mining Engineering Operative Unit – Department of Prevention), M. Ferrari, M. Profeti and V. Carnicelli (Cooperativa Cavatori Lorano), X. Chaoshui and P.A. Dowd (School of Civil, Environmental and Mining Engineering, University of Adelaide, South Australia) and M. Bocci (Geographike) for their support of this research

Application of an integrated geotechnical and topographic monitoring system in the Lorano marble quarry (Apuan Alps, Italy)

PublishedThis is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.geomorph.2015.04.009Accurate slope stability analysis is essential for human activity in high-risk geological contexts. This may, however, not be enough in the case of quarrying where the dynamic and evolving environment also requires effective monitoring. A well-designed monitoring system requires the acquisition of a huge dataset over time, improving knowledge of the study area and helping to refine prediction from stability analysis.This paper reports the implementation of an integrated monitoring system in a marble quarry in the Apuan Alps (Italy) and some of the results obtained. The equipment consists of a traditional geotechnical monitoring system (extensometers, crackmeters and clinometers) and two modern topographic monitoring systems (a terrestrial interferometer and a robotic total station). This work aims to provide in-depth knowledge of the large scale rock mass behaviour as a result of marble exploitation, thereby allowing continuous excavation. The results highlight the importance of integrating different monitoring systems.The present study was undertaken within the framework of the Italian National Research Project PRIN2009, funded by the Ministry of Education, Universities and Research, which involves the collaboration between the University of Siena, “La Sapienza” University of Rome, and USL1 of Massa and Carrara (Mining Engineering Operative Unit - Department of Prevention)

A GPU-based survey for millisecond radio transients using ARTEMIS

Astrophysical radio transients are excellent probes of extreme physical processes originating from compact sources within our Galaxy and beyond. Radio frequency signals emitted from these objects provide a means to study the intervening medium through which they travel. Next generation radio telescopes are designed to explore the vast unexplored parameter space of high time resolution astronomy, but require High Performance Computing (HPC) solutions to process the enormous volumes of data that are produced by these telescopes. We have developed a combined software /hardware solution (code named ARTEMIS) for real-time searches for millisecond radio transients, which uses GPU technology to remove interstellar dispersion and detect millisecond radio bursts from astronomical sources in real-time. Here we present an introduction to ARTEMIS. We give a brief overview of the software pipeline, then focus specifically on the intricacies of performing incoherent de-dispersion. We present results from two brute-force algorithms. The first is a GPU based algorithm, designed to exploit the L1 cache of the NVIDIA Fermi GPU. Our second algorithm is CPU based and exploits the new AVX units in Intel Sandy Bridge CPUs.Comment: 4 pages, 7 figures. To appear in the proceedings of ADASS XXI, ed. P.Ballester and D.Egret, ASP Conf. Se

A case study integrating remote sensing and distinct element analysis to quarry slope stability assessment in the Monte Altissimo area, Italy

This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.enggeo.2014.09.003. First available online 22 September 2014Over last decade geomatic techniques have been increasingly used for the geometrical characterization of rock slopes. Terrestrial laser scanning and digital terrestrial photogrammetry in particular are now frequently used in the characterization of joint surfaces and slope geometry. Although the use of these techniques for the structural characterization of slopes is widely documented, limited research has been undertaken to improve our understanding of the importance of the derived data quality in the construction of slope geometry imported into 3D numerical models. One of the most common problems encountered in the use of these techniques, especially in case of slopes with complex geometry, is the presence of occlusions. In this context, the aims of this paper are to describe how the integrated use of terrestrial laser scanning, digital terrestrial photogrammetry and topographic surveys can mitigate the influence of occlusions and how the slope geometry gained from these surveys can be important in slope stability analyses. For this purpose a case study in the Monte Altissimo area (Apuan Alps, Italy) will be presented. Several geomatic techniques were used for studying a slope overhanging the Granolesa quarry. Special emphasis will be given to the importance of using Total Station and Differential GPS surveys as tools for data fusion. Moreover, in order to validate this procedure, the accuracy and precision of the output were determined through comparison of 3D models derived from laser scanning and digital terrestrial photogrammetry.Furthermore, two different analyses with the three-dimensional distinct element code, 3DEC, were carried out in order to highlight the advantages and limitations of using data obtained from terrestrial remote sensing techniques as opposed to models based on topographic maps.The authors wish to thank the Tuscany Region which funded this research (Announcement 6744/2008 POR CREO 2007–2013). Moreover, we are extremely grateful to Henraux S.p.A., Prof. Pier Lorenzo Fantozzi (University of Siena), Geol. Sergio Mancini, Geol. Vinicio Lorenzoni and Ing. Matteo Lapini (Ingeo Systems s.r.l.) for their assistance and advices in this research

An integrated remote sensing-GIS approach for the analysis of an open pit in the Carrara marble district, Italy: slope stability assessment through kinematic and numerical methods

PublishedJournal Article© 2015 Elsevier Ltd. Over the last decade, terrestrial laser scanning and digital terrestrial photogrammetry techniques have been increasingly used in the geometrical characterization of rock slopes. These techniques provide innovative remote sensing tools which overcome the frequent problem of rock slope inaccessibility. Comprehensive datasets characterizing the structural geological setting and geometry of the slopes can be obtained. The derived information is very useful in rock slope investigations and finds application in a wide variety of geotechnical and mine operations. In this research an integrated remote sensing - GIS approach is proposed for the deterministic kinematic characterization of the Lorano open pit in the Apuan Alps of Italy. Based on the results of geomatic and engineering geological surveys, additional geomechanical analysis using a 3D finite difference method will be presented in order to provide a better understanding of the role of stress-induced damage on slope performance