Studio della propagazione della frattura in polibutene per tubi

Il Polibutene-1 isotattico (i-PB1) è un materiale polimerico usato per la produzione di tubi per il trasporto di fluidi in pressione. In questo lavoro si sono studiati due tipi di i-PB1 prodotti da Basell che differiscono per grado di isotatticità. Si sono condotte prove di frattura a diverse temperature e velocità di spostamento imposte. Si è utilizzata una configurazione di flessione su provini con singolo intaglio (SENB) unitamente a quella di doppia trave a sbalzo (DCB), quest’ultima limitatamente allo studio della fase di propagazione. Al fine di individuare con precisione l’innesco della frattura e la velocità di propagazione della stessa si è fatto ricorso a metodi ottici. Dal punto di vista fenomenologico durante la propagazione si assiste alla formazione di zone in cui il materiale risulta fortemente stirato. La frattura in esse avanza con una lacerazione continua che si alterna a salti repentini in occasione del brusco cedimento di queste zone, associato a conseguenti cadute del carico. Questa parziale instabilità è stata osservata sui due materiali per entrambe le configurazioni di prova. I risultati ottenuti sono stati interpretati seguendo l’approccio della meccanica della frattura e applicando uno schema di riduzione di tipo tempo-temperatura che ha permesso di descrivere il comportamento viscoelastico del materiale su un intervallo temporale di diverse decadi. I risultati hanno permesso di applicare un modello analitico per la previsione della vita utile di tubi in pressione. Il modello si è mostrato in buon accordo con i dati sperimentali disponibili da prove condotte su tubi dello stesso materiale

tetraxial textiles assessment of mesoscale mechanical modelling by experimental measurements

Tetraxial technical textiles were recently manufactured by a new loom developed to weave yarns in four directions. The textile has warp, weft, and two diagonal yarns oriented at symmetrical angles (typically ±45°) with respect to the warp direction. The peculiar yarns distribution could enhance the mechanical response of the textile in multiple directions aiming to almost isotropic in-plane behaviour. For the prediction of the mechanical performance of such tetraxial textiles, a reliable and accurate predictive model is of relevant importance. The present investigation aims to adopt the finite element numerical approach at the mesoscopic scale to predict the mechanical response for any in-plane loading of tetraxial textiles. An accurate modelling of the constitutive behaviour of the fibrous yarns was adopted considering a hyperelastic model. The modelling of the tetraxial unit cell allowed to have the mechanical behaviour for uniaxial and biaxial tensile and for shear loading conditions. The assessment of the accuracy of the numerical model was performed considering a huge experimental campaign dedicated to several hybrid tetraxial textiles. The comparison highlights the accuracy of the numerical model to predict the nonlinear behavior of the fabric for any loading condition and to provide the proper mechanical model for further optimization of tetraxial textiles supposed for different industrial applications

“Mura della Bastia” – Onigo di Pederobba (Treviso). Ricerche archeologiche, rilievo 3D laser scanning e anastilosi virtuale in un castello medievale del pedemonte trevigiano

The paper presents the results of the ongoing research coordinated by the Chair of Ancient Topography at the University of Padova. The work concerns the medieval site of “Mura della Bastia” in Onigo di Pederobba (Treviso), in the North-Eastern part of Italy. Historical information from written documents and results obtained from the archaeological investigation at the Onigo castle (1994-2007) are discussed. The study provided the historical reconstruction of recent collapses of the Onigo tower and allowed the virtual reconstruction of still-cohesive blocks, which had fallen down in 1989, and which were recovered during the summer of 2007. At this time, five of the ten building blocks have been positioned; the procedure was carried out by comparing the panoply of each agglomerate with the prospect of the tower, which was obtained from the photogrammetric rectification of the historical images (2D). The 3D survey of the tower and of nine blocks was performed with a Leica HDS 2500 laser scanner. The resulting point clouds were aligned with Cyclone software, also using the coordinates of some laser scanning targets, which were measured with the Leica TC 2003 total station in a local reference system. The final 3D model obtained by the co-registration of the scans was textured with the digital images acquired with a Canon EOS 1 ds Mark II camera. Subsequently, three of the five recognized blocks were positioned on the 3D model using Reconstructor software

Optical Properties and Ultrafast Near‐Infrared Localized Surface Plasmon Dynamics in Naturally p‐Type Digenite Films

Copper chalcogenides are materials characterized by intrinsic doping properties, allowing them to display high carrier concentrations due to their defect-heavy structures, independent of the preparation method. Such high doping enables these materials to display plasmonic resonances, tunable by varying their stoichiometry, as shown previously for Cu2-xS, Cu2-xSe, and Cu2-xTe, with 0 1 ns) signal associated with phonon-phonon scattering relaxation. These results confirm the possibility of fabricating Cu9S5 films retaining the plasmonic properties of individual NCs, anticipating integrating these films into heterojunctions with suitable hole acceptor materials to build hot-hole-transfer-based optoelectronic devices

ccdc80-l1 Is Involved in Axon Pathfinding of Zebrafish Motoneurons

Axon pathfinding is a subfield of neural development by which neurons send out axons to reach the correct targets. In particular, motoneurons extend their axons toward skeletal muscles, leading to spontaneous motor activity. In this study, we identified the zebrafish Ccdc80 and Ccdc80-like1 (Ccdc80-l1) proteins in silico on the basis of their high aminoacidic sequence identity with the human CCDC80 (Coiled-Coil Domain Containing 80). We focused on ccdc80-l1 gene that is expressed in nervous and non-nervous tissues, in particular in territories correlated with axonal migration, such as adaxial cells and muscle pioneers. Loss of ccdc80-l1 in zebrafish embryos induced motility issues, although somitogenesis and myogenesis were not impaired. Our results strongly suggest that ccdc80-l1 is involved in axon guidance of primary and secondary motoneurons populations, but not in their proper formation. ccdc80-l1 has a differential role as regards the development of ventral and dorsal motoneurons, and this is consistent with the asymmetric distribution of the transcript. The axonal migration defects observed in ccdc80-l1 loss-of-function embryos are similar to the phenotype of several mutants with altered Hedgehog activity. Indeed, we reported that ccdc80-l1 expression is positively regulated by the Hedgehog pathway in adaxial cells and muscle pioneers. These findings strongly indicate ccdc80-l1 as a down-stream effector of the Hedgehog pathway

RAPTOR: archeologia e tutela. Verso la pubblica amministrazione digitale

RAPTOR is a project, still under development, designed to build a simple and versatile tool in order to computerize the administrative procedures of the Italian Superintendence for Archaeological Heritage. Its purpose is to ensure a faster response to all kinds of external requests and to align, as much as possible, the Superintendency offices to the new Code of Digital Administration (CAD). RAPTOR geodatabase is based on open source software PostgreSQL and PostGIS, while the web-interface management is provided by PHP, JavaScript, GeoServer and OpenLayers. In this way all vector data can be entered into the system through specific compilation forms and displayed on a map, where they can also be queried. In short, RAPTOR will provide the users a complete and accurate mapping module, which will be able to show in real time a thematic cartography provided both with known archaeological evidence and negative areas

"Mura Bastia". Dati archeologici, informatizzazione e rilievi 3D laser scanning del Castello degli Onigo (Pederobba, Treviso)

This paper concerns computer applications for the management of archaeological data through GIS software, as related to the 2008 excavation campaign at “Mura Bastia”, Onigo (Treviso), Italy. The approach allows for the correlation of data previously acquired with those collected more recently using newer technologies. The shift from the traditional way of drawing archaeological records to the new digital technique began during the excavation of 2007. All of the walls and the layers were documented using a total station and a digital camera (photo-mosaic method). The elaboration of raw data was obtained using Free and Open Source Software only (GRASS, E-FOTO, GIMP, OPENJUMP, gvSIG). All of the new information levels (bi-dimensional raster and vector layers) were connected with the digitized plan of the old excavation into a GIS project that became the final product of the whole work. 3D terrestrial laser scanning surveys, integrated with classical topography and digital photogrammetric methodologies, allowed us to extract an accurate and photorealistic digital model of the Onigo castle. Moreover, a partial 3D virtual anastylosis of the tower was completed thanks to the reallocation of two missing elements in their correct position

The flood of the 6th century ad in the Tagliamento River (NE Italy): geomorphological and geoarchaeological evidence of the Medieval Diluvium

In the Mediterranenan basin, strong geomorphic processes occurred in several areas during the early Middle Age. In some alluvial plains a fast and strong activity phase was triggered and this led many rivers to avulse and/or to form widespread alluvial depositional units. According to some scholars, the severe flooding episode described by the Lombard historian Paolo Diacono as the aquae diluvium of 589 AD, corresponds to one of the most significant phases occurred in Northern Italy, even if its importance and areal extent is debated (Cremonini et al., 2013). Major changes are clearly testified in the alluvial systems of NE Italy and a wealth of information is especially documented in the alluvial megafan of Tagliamento River, both in the stratigraphic and in the archaeological records. Between the 5th and 9th century, the Tagliamento River experienced its last strong avulsive phase, with the abandonment of the path followed since the beginning of the 1st millennium BC (Lugugnana branch) and the activation of the branches of Concordia Sagittaria and Latisana; these two directions are 15 km a part one from the other but, at the end of this period, only the branch of Latisana survived. The temporary activation of the branch of Concordia is clearly documented by the alluvial unit that sealed large sectors of the Roman city of Concordia Sagittaria with a thickness of 1-5 m of silty sands, burying also the floor of the palaeo-Christian basilica, which is dated to the first part of the 6th century (Fontana, 2006; Fontana et al., 2014). In Cordovado, 10 km upstream of Concordia, a recent excavation exposed part of a gravelly braided palaeochannel with several embedded trunks, up to 5-meters long. Their radiocarbon dating measured a calibrated age between the second half of 6th century and the first part of the 7th, well matching the time of the hydraulic disaster described by Paolo Diacono (Frassine et al., 2014). Along the present direction of Tagliamento, the river formed a fluvial ridge reaching up to 4 m over the surrounding floodplain and sealed the Roman landscape. This elevated landform rapidly became an attracting feature for the early Medieval villages and, in Latisana, its first occupation is dated at least since the 11th century. The depositional period coinciding with the avulsive phase was also characterized by the structuration of the present cuspate delta of Tagliamento, consisting of 2 wings where now the tourist cities of Lignano Sabbiadoro and Bibione are present (Fontana, 2006). Since early studies, many Authors considered this Early Medieval period both for its archaeological and geomorphic importance, trying to sort out the natural from the human-induced component. Several papers stressed the importance of the coincidence between an important natural event/events and the lack of territorial management, particularly when compared to the strong anthropogenic control occurred in the centuries before. New stratigraphic and geomorphologic data from the megafan of Tagliamento support the assessment of the magnitude of the natural component (mainly driven by climate) of the alluvial processes occurred in the early Middle Ages. In particular, the chronological information allows to constrain one of the main flooding phases between the second half of the 6th and the first part of the 7th century. This evidence confirms the importance of so-called \u201cDiluvium\u201d described by Paolo Diacono but, in the Tagliamento River, the alluvial period lasted until the 10th-11th century

Un prototipo di Augmented Reality per la valorizzazione della villa romana di Torre di Pordenone (Friuli Venezia Giulia)

In 2008 a new excavation project started in the archaeological site of the Castle of Torre di Pordenone (Friuli Venezia Giulia, Italy), thanks to the efforts of the Municipality of Pordenone. During the archaeological campaign, a new rectangular building was discovered, in connection with the Roman villa already investigated in the 1930s. This building is divided into at least nine consecutive areas and the W side has a porticus supported by 8 pillars. Given the nature of the architectural elements, which are preserved in almost all cases at the foundation level, the Soprintendenza per i Beni Archeologici del Friuli Venezia Giulia (Nucleo Operativo di Pordenone), in cooperation with the Municipality of Pordenone and the Museo Archeologico del Friuli Occidentale, decided to test modern information technologies, in order to create a virtual tour, based on an accurate 3D reconstruction of the Roman building. The final prototype, developed for the project, has an Augmented Reality level that can be visualized through video-glasses (Head Mounted Display), thanks to the interaction with a high definition webcam and a tablet equipped with open source software