Terrestrial laser scanning, geomorphology and archaeology of a Roman gypsum quarry (Vena del Gesso Romagnola area, Northern Apennines, Italy)

Roman-period extractive sites in gypsum outcrops are very rare, and most have become very degraded by later weathering or quarrying activities. This paper describes, using laser scanning, photogrammetry and survey using a UAV-based survey, the uniquely well-preserved Roman-period gypsum quarry of Ca’ Castellina (Northern Apennines, Italy). This site was excavated only in the last few years and the excavations have brought to light some gypsum blocks and the ancient quarry benches showing excavation marks, the remains of a rectangular building and a great number of artefacts that range between the Protohistoric Period and the modern times. The size of the extracted blocks, the extraction methodologies and the age of a charcoal fragment (361 – 178B CE) found immediately at the contact between the gypsum quarry floor and the infilling sediments date the quarry back to the Roman age. Archaeological evidences demonstrate the building to have been used for a short period of time during the XVI-XVII century. Immediately after its abandonment most of the quarry floor has been covered with a thick detrital layer, protecting it from dissolution (fossilizing this floor and leaving it as if it was abandoned very recently), whereas the naked or poorly covered floor of this quarry has been subjected to dissolution phenomena of the exposed gypsum rocks, with a lowering of the surface, the smoothening of the corners and the formation of a set of deeply carved karren features. A 3D survey using both a laser scanning instrument and a drone-mounted photo camera have allowed to get precise measures on the size of the blocks that were extracted in this quarry, the traces of pick axe marks, and on the dissolution morphologies that have developed on the bare gypsum rock. These typical gypsum landforms show how fast these solution forms can develop where concentrated runoff flows on bare gypsum. To prevent this exceptional archaeological extractive site of being further dissolved, it will be important to plan some measures to be put in place in order to protect this delicate historical landmark

Modellimg and experimental charaterization of unsaturated flow in absorbent and swelling porous media

The present study aims at characterizing relevant morphological and hydraulic properties of absorbent hygiene products (AHP), consisting of storage layers made of cellulose fluff fibres and super absorbent polymer (SAP) particles, with different SAP/fluff ratio (SFR). The dependencies of these properties (e.g. porosity and hydraulic conductivity) on the absorption extent of the SAP particles has to be clearly acknowledged, in order to properly model with continuous assumptions this particular porous system. A comprehensive tailored experimental protocol is presented for the characterization of properties and constitutive parameters relevant to AHP performance. The results have been directed to set the closure equations and constitutive parameters of multiphase flow models in which the porous media is treated as a continuum. Computational fluid dynamics simulations were used to test the obtained closure equations. The performances of the composite materials have been characterized in terms of absorption time and absorbed fluid spatial distribution upon iterated imbibition/drainage cycles. A multi-scale approach was implemented using a model based on a discrete element method (DEM). Virtual experiments in DEM simulation were carried out and compared to the lab measurements

Monitoring of the Nirano Mud Volcanoes Regional Natural Reserve (North Italy) using Unmanned Aerial Vehicles and Terrestrial Laser Scanning

In the last years, measurement instruments and techniques for three-dimensional mapping as Terrestrial Laser Scanning (TLS) and photogrammetry from Unmanned Aerial Vehicles (UAV) are being increasingly used to monitor topographic changes on particular geological features such as volcanic areas. In addition, topographic instruments such as Total Station Theodolite (TST) and GPS receivers can be used to obtain precise elevation and coordinate position data measuring fixed points both inside and outside the area interested by volcanic activity. In this study, the integration of these instruments has helped to obtain several types of data to monitor both the variations in heights of extrusive edifices within the mud volcano field of the Nirano Regional Natural Reserve (Northern Italy), as well as to study the mechanism of micro-fracturing and the evolution of mud flows and volcanic cones with very high accuracy by 3D point clouds surface analysis and digitization. The large amount of data detected were also analysed to derive morphological information about mud-cracks and surface roughness. This contribution is focused on methods and analysis performed using measurement instruments as TLS and UAV to study and monitoring the main volcanic complexes of the Nirano Natural Reserve as part of a research project, which also involves other studies addressing gases and acoustic measurements, mineralogical and paleontological analysis, organized by the University of Modena and Reggio Emilia in collaboration with the Municipality of Fiorano Modenese

A Natural Laboratory for Understanding Volcano-Speleogenetic Processes and Planetary Caves

The volcanic island of Lanzarote hosts an impressive variety of cavities formed by different volcanic processes. The presence of well preserved lava fields belonging to historic eruptions and more ancient and weathered quaternary and pliocene terrains and the association with an arid climate provide the unique opportunity of studying volcanic caves at different stages of evolution on the same volcanic island. The different mechanisms of lava tube emplacement can be observed in great detail, from the most recent pyroducts of different sizes formed during the Timanfaya eruption (1730–1736) to the exceptionally voluminous conduits of the Corona volcano, formed during the Last Glacial Maximum and partially submerged by the sea level upraise during the Holocene. In addition, other type of cavities, like explosive and geyser vents, “hornitos” and sinkholes in pyroclastic deposits offer the opportunity to extend the study to other important volcano-speleogenetic processes in different settings. All these cavities are easily accessible and present a variety of morphological, mineralogical, biological and microbiological significances, allowing for a wide range of multidisciplinary studies. The countless analogies with lava tube collapses and other potential volcanic cave features detected on the Moon and Mars also provide an unprecedented research ground that offers hints to solve some open issues in the interpretation of still unresolved planetary cavities. These characteristics make the Lanzarote and Chinijo Islands UNESCO Global Geopark an exceptional case where the protection and scientific outreach has been extended to the volcanic subsurface. In this chapter we offer a review of the current knowledge and existing scientific studies on the volcanic caves of Lanzarote and we discuss future researches and protection issues that need to be addressed in order to fully include this geoheritage in strategic plans of environmental protection

Laser scanner survey and tru view applications of the "Grotta della lucerna" (Ravenna, Italy), a roman mine for lapis specularis

The Grotta della Lucerna (Lamp's Cave) is a small cavity (about 400 m long and 36 m depth) located in the Regional Park of Vena del Gesso Romagnola, in Zattaglia (Ravenna, Italy). This cave represent one of the few documented mining sites of Lapis Specularis in Italy, a particular type of secondary gypsum that was mined in Roman times and worked to obtain thin transparent cleveage sheets used for windows. Crystal processing traces and artificial changes made to facilitate the exploitation and transport of the raw material are visible in all areas currently explored. The archeological findings allow to constrain the period of exploitation between the 1st and the 4st century CE. We performed a laser scanner survey of the most accessible areas of the cave by carrying out 33 scans inside and 3 outside the cave. The data analysis allowed the costruction of a tridimensional model, from which it was possible to draw plans and sections with very high centimetric accuracy. With the Leica True View applications it was also possible to produce an interactive model wich permits the navigation inside the point data, with the possibility to move between the scans. Other operations are also possible such as distance measurements, notes and coordinates input, snap print directly by photos and points misured with the laser. This application has been used also for the drawing operations in bi-dimentional mode using the Cloudworks plug-in that allows to draw line and polyline directly from the True View in Auto-Cad. La Grotta della Lucerna \ue8 una piccola cavit\ue0 con uno sviluppo planimetrico di circa 400 m e 36 m di dislivello, situata Parco della Vena del Gesso Romagnola. Questa grotta rappresenta uno dei rari siti di estrazione di Lapis Specularis attualmente documentati in Italia, un particolare tipo di gesso secondario che veniva estratto in epoca romana per ricavare sottili lastre da utilizzare allo stesso modo delle lastre di vetro per finestre. Tracce di lavorazione ed adattamenti artificiali per facilitare i lavori di estrazione del materiale sono numerose e presenti in quasi tutte le zone della grotta attualmente esplorate. I ritrovamenti archeologici hanno aiutato a inquadrare il periodo di sfruttamento della grotta in miniera tra il I e il IV sec. d.C.. Per effettuare il rilevamento con laser scanner delle zone pi\uf9 accessibili della grotta sono state effettuate 33 scansioni all'interno e 3 all'esterno della cavit\ue0. L'analisi dei dati ottenuti ha permesso di ricavare un modello tridimensionale da cui \ue8 stato possibile ottenere piante e sezioni con una precisione centimetrica. Attraverso l'applicazione Leica True View \ue8 stato successivamente realizzato un modello interattivo che permette la navigazione all'interno del rilievo, in cui \ue8 possibile muoversi tra le varie scansioni ed eseguire diverse operazioni tra le quali misure di distanze, inserimento di testi, snap print, inserimento di coordinate direttamente dalle fotografie e dai punti di misura. Questa applicazione \ue8 stata utilizzata anche per realizzare i modelli bi-dimensionali tramite il plugin di Cloudworks, con il quale \ue8 stato possibile disegnare direttamente dal True View sul foglio di disegno in ambiente cad

Impact experiments of char and ash particles relevant to entrained-flow coal gasifiers

The present study addresses particle-wall interaction phenomena relevant to entrained-flow coal gasifiers. The dynamics of coal, char and ash particles as they are impacted onto a flat surface in cold and hot conditions and undergo momentum transfer and rebound, has been characterized by means of high speed imaging and tracking. Particle-wall collisions were described in terms of normal, tangential and global restitution coefficients. The influence of carbon conversion, impact velocity and surface properties and structure of the target on the dynamical pattern of rebound has been scrutinized. The results indicate that, even at ambient conditions, some plastic deformation occurs during the impact. The restitution coefficients decreased as temperature and carbon conversion increased. This feature was more pronounced at large carbon conversion, confirming the criticality of the char/slag transition to particle deposition on the wall. The dissipation of momentum associated with particle impact may promote the establishment of a dense-dispersed phase in the near-wall zone of entrained-flow slagging gasifiers