SHEER “smart” database: technical note

The SHEER database brings together a large amount of data of various types: interdisciplinary site data from seven independent episodes, research data and those for the project results dissemination process. This concerns mainly shale gas exploitation test sites, processing procedures, results of data interpretation and recommendations. The smart SHEER database harmonizes data from different fields (geophysical, geochemical, geological, technological, etc.), creates and provides access to an advanced database of case studies of environmental impact indicators associated with shale gas exploitation and exploration, which previously did not exist. A unique component of the SHEER database comes from the monitoring activity performed during the project in one active shale gas exploration and exploitation site at Wysin, Poland, which started from the pre-operational phase. The SHEER database is capable of the adoption of new data such as results of other Work Packages and has developed an over-arching structure for higher-level integration

When instrument location makes the difference on rainfall thresholds definition: Lessons learned at Cancia, Dolomites

Since debris flows represent one of the most dangerous natural hazard in mountain areas, Early Warning Systems (EWSs) play a crucial role in reducing the risk of these hazardous processes. Robust event pre-alert usually relies on long time series of local rainfall measures. Oftentimes regional rain gauge networks present an insufficient spatial density to grasp the highly variable spatio-temporal dynamics of debris-flow triggering events and thus relying on such networks for developing rainfall thresholds might lead to relatively low rainfall estimates. The present paper reports the development of operational rainfall thresholds for the Cancia EWS, Dolomites (NE Italy). The instrumentation configuration led to the derivation and implementation of a set of rainfall thresholds that significantly enhanced pre-alarm reliability thanks to an optimal spatial distribution of multiple rain gauges within the catchment. Notwithstanding the small number of debris flows occurred during the calibration period, rainfall thresholds were derived considering the whole population of rainfall events showcasing the statistical properties of those events that led to debris-flow initiation. Finally, the validation period served as proof of work for the proposed thresholds with no raised false alarms and with the identification of few minor, but correctly detected, debris flows

Graphene nanoplatelets render poly(3-hydroxybutyrate) a suitable scaffold to promote neuronal network development

The use of composite biomaterials as innovative bio-friendly neuronal interfaces has been poorly developed so far. Smart strategies to target neuro-pathologies are currently exploiting the mixed and complementary characteristics of composite materials to better design future neural interfaces. Here we present a polymer-based scaffold that has been rendered suitable for primary neurons by embedding graphene nanoplatelets (GnP). In particular, the growth, network formation, and functionality of primary neurons on poly(3-hydroxybutyrate) [P(3HB)] polymer supports functionalized with various concentrations of GnP were explored. After growing primary cortical neurons onto the supports for 14 days, all specimens were found to be biocompatible, revealing physiological growth and maturation of the neuronal network. When network functionality was investigated by whole patch-clamp measurements, pure P(3HB) led to changes in the action potential waveform and reduction in firing frequency, resulting in decreased neuronal excitability. However, the addition of GnP to the polymer matrix restored the electrophysiological parameters to physiological values. Interestingly, a low concentration of graphene was able to promote firing activity at a low level of injected current. The results indicate that the P(3HB)/GnP composites show great potential for electrical interfacing with primary neurons to eventually target central nervous system disorders

A model-based early warning system for runoff-generated debris-flow occurrence: Preliminary results

Early warning systems for debris flows are low cost measures for mitigating this kind of hazard. The early warning systems provide a timely alert for upcoming events in order to take protective measures, such as closing railways-roads, evacuating people from the threatened areas, and put rescue forces into readiness. These systems usually are sensor-based, and the alert time is the interval between the timing of the first detachment of debris flow by a sensor and its arrival into the threatened area. At the purpose of increasing the alert time, we propose an early warning system based on a model-cascade: nowcasting, hydrological- and triggering models. Nowcasting anticipates rainfall pattern that is transformed into runoff by the hydrological model. The triggering model estimates the volume of sediments that the runoff can entrain, and compares it with a critical threshold. If this is exceeded the alert is launched. The proposed early warning system is tested against the available data of the Rovina di Cancia (Northeast Italy) site

Studio dei meccanismi di deposizione dei Debris Flow: integrazioni tra esperienze di laboratorio, analisi di campo e modellazioni numeriche

This research is related to the study and modelling of the depositional processes of debris flows and an understanding of the related rheological behaviour. The main aims of this study are to analyse the depositional features of a debris flow, to verify the possible contribution of laboratory tests, carried out by means of a tilting-plane rheometer, to determine the rheological parameters and to investigate the reliability and limitations of computer models employed for debris flow simulation and rheological parameter determination. The laboratory tests were been carried out at the Institute for Hydrological and Geological Protection of the Italian National Research Council (CNR IRPI) in Padova. The physical model consists of a 2 x 1 m tilting plane with inclination from 0° to 38°, on which a steel tank with a removable gate has been installed. A fixed horizontal plane (1.5 x 1 m), with an artificial roughness to simulate natural basal friction, served as the deposition area. In total, 93 laboratory tests were carried out: 62 tests simulated the quasi-static formation of a fan (with the tank installed at the lower end of the tilting plane), the remaining 31 examined dynamic fan formation by the means of a flume. The steel tank, with a removable gate facing the deposition plane, is parallelepiped with a square base (15 x 15 cm and 33 cm high) having a maximum volume of 7 dm3. The laboratory tests were conducted using three different materials: plastic cylinders with a diameter and height of 3 mm; medium to fine gravel; and debris-flow matrix (with a diameter < 19 mm), varying amounts of water were added to the debris-flow matrix to test solid concentrations in a range between 0.45 and 0.67. Data analysis included the development of semi-empirical equations for runout distance, the maximum width of the deposit and total travel distance. An energy balance approach was tested in order to determinate the rheological parameters of the debris-flow matrix, this method is based on the comparison between the potential energy of the mass stored in the tank and the work made in the process of deposit formation. The field sites related to the debris-flow events are located upstream of the town of Cortina d'Ampezzo (Fiames locality, Belluno, Italy), where an intense rainstorm triggered six debris flows during the afternoon of 5th July 2006. Immediately following the event, field surveys were carried out in the study area. These field surveys made it possible to measure several features, including the debris-flow deposits, main channels and initiation areas. Samples taken from the debris-flow deposits have been used for laboratory tests. Total travel distances and the runout distance on fans measured in the field were compared with formulas found in the literature (empirical/statistical and physically oriented) and also compared to the results of the laboratory tests. An estimation of shear stress from the field site was calculated using Johnson's (1970) formula. The Fiames debris-flow event of 5th July 2006 and the laboratory tests (dynamic runs) were simulated using FLO-2D, while RAMMS (Rapid Mass MovementS) was used solely to simulate the Fiames event. FLO-2D (O'Brien, 2003) is a two-dimensional flood routing model with a rigid bed (debris-flow simulations) or a mobile bed (sediment transport simulations), it simulates water flows in wide rivers as well as non-Newtonian flows over alluvial fans. FLO-2D numerically routes a flood hydrograph while predicting the area of inundation, the maximum depth and the flow velocity in each cell of the square grid system derived from input topographic data. RAMMS was developed in 2005 by the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf and the Swiss Federal Institute for Snow and Avalanche Research (SLF), Davos. RAMMS uses a one-phase approach based on Voellmy rheology (Voellmy, 1955; Salm et al. 1990). The input file combines the total volume of the debris flow located in a release area with a mean depth. The model predicts the area of inundation, the maximum depth and the flow velocity in each triangular-shape cell of the input DTM. The limitations of the numerical simulations relating to the laboratory tests were investigated to verify to what extent rheological parameters could be determined using this indirect method. The analysis of the Fiames event enabled understanding of the rheological behaviour related to the dolomitic debris-flows and the influence exerted by the input parameters on the final results. Finally, some improvements to the RAMMS model were proposed to obtain simulations in keeping with the events observed in the field

Reologia e distanza di arresto dei debris flow: sperimentazioni su modello fisico a piccola scala

Lo studio di campo delle caratteristiche di movimento delle colate fangose e fangoso-detritiche (debris flow) presenta delle notevoli difficolt\ue0 tecniche e operative a causa dell\u2019imprevedibilit\ue0 temporale del fenomeno, della sua breve durata e dell\u2019elevata forza distruttiva del flusso. Per questa ragione l\u2019uso di modelli fisici a scala ridotta pu\uf2 considerarsi un valido strumento di indagine per l\u2019analisi reologica dei debris flow o quanto meno della loro componente medio-fine (ghiaie, sabbie, limi, argille), che ne condiziona fortemente gli sforzi deformativi di tipo viscoso, frizionale e collisionale. In questo ambito si sono svolte alcune prove sperimentali mediante un reometro a piano inclinato, costituito da una canaletta, lunga 2 m, seguita da un piano orizzontale che funge da zona di deposizione. La canaletta \ue8 dotata di un serbatoio per il carico delle miscele fangoso-granulari, dal quale vengono poi rilasciati impulsivamente, a mezzo di una paratoia, flussi a concentrazione volumetrica nota. Sono state testate alcune miscele costituite da sedimenti campionati da recenti depositi di colata: due campioni (uno indisturbato ed uno rimaneggiato) provengono da un debris flow verificatosi in zona Dolomitica (falde del massiccio del Pomagagn\uf2n, Cortina d\u2019Ampezzo, Belluno) e sono caratterizzati da diverse percentuali dei sedimenti coesivi, un terzo campione \ue8 composto da materiale prevalentemente sabbioso prelevato dalla colata del rio Gabbiolo (affluente del torrente Sarca di Val Genova, Trento), un ultimo campione (rio Val degli Schivi, Trento) presenta un discreto assortimento di sedimenti a grana grossa e a grana fine. Le prove sperimentali hanno portato a determinare delle relazioni piuttosto strette tra la pendenza media di attrito dei vari flussi gravitativi e la loro concentrazione volumetrica, mettendo in luce come la composizione granulometrica dei sedimenti ne influenzi grandemente la mobilit\ue0. Le sperimentazioni hanno inoltre suggerito un metodo per la stima della distanza di arresto, che \ue8 stato verificato mediante il confronto con eventi reali

Basal shear stress of debris flow in the runout phase

A laboratory device is proposed to assess the basal shear stresses generated by debris-flow mixtures during their runout phase. The device consists of an inclinable box with a gate facing a deposition plane. The box is filled with a selected debris-flow mixture, and after sudden opening of the gate, the features of the dam-break deposit can be measured. Based on some simplified assumptions of the energy balance, a methodology is proposed to assess basal shear stresses. The device has been tested using sediment samples from debris-flow deposits generated by two catchments of the Dolomites (Cortina d'Ampezzo, Belluno, Italy) by carrying out runout tests for different sediment concentrations by volume. The results show how the static Coulomb friction law is valid in the runout phase, with friction angles on the order of the angle of repose of the same material in dry conditions. The data elaboration also yields an innovative constitutive equation for shear stresses. This relation merges the Coulomb mixture approach with the concept of a one-phase flow with a certain rheology. This integration offers a useful insight into the weaknesses of the rheological approach if it is not properly scaled up to the ambient pressure of interest

When instrument location makes the difference on rainfall thresholds definition: Lessons learned at Cancia, Dolomites

Since debris flows represent one of the most dangerous natural hazard in mountain areas, Early Warning Systems (EWSs) play a crucial role in reducing the risk of these hazardous processes. Robust event pre-alert usually relies on long time series of local rainfall measures. Oftentimes regional rain gauge networks present an insufficient spatial density to grasp the highly variable spatio-temporal dynamics of debris-flow triggering events and thus relying on such networks for developing rainfall thresholds might lead to relatively low rainfall estimates. The present paper reports the development of operational rainfall thresholds for the Cancia EWS, Dolomites (NE Italy). The instrumentation configuration led to the derivation and implementation of a set of rainfall thresholds that significantly enhanced pre-alarm reliability thanks to an optimal spatial distribution of multiple rain gauges within the catchment. Notwithstanding the small number of debris flows occurred during the calibration period, rainfall thresholds were derived considering the whole population of rainfall events showcasing the statistical properties of those events that led to debris-flow initiation. Finally, the validation period served as proof of work for the proposed thresholds with no raised false alarms and with the identification of few minor, but correctly detected, debris flows

GaN-based laser wireless power transfer system

The aim of this work is to present a potential application of gallium nitride-based optoelectronic devices. By using a laser diode and a photodetector, we designed and demonstrated a free-space compact and lightweight wireless power transfer system, whose efficiency is limited by the efficiency of the receiver. We analyzed the effect of the electrical load, temperature, partial absorption and optical excitation distribution on the efficiency, by identifying heating and band-filling as the most impactful processes. By comparing the final demonstrator with a commercial RF-based Qi system, we conclude that the efficiency is still low at close range, but is promising in medium to long range applications. Efficiency may not be a limiting factor, since this concept can enable entirely new possibilities and designs, especially relevant for space applications

Impact of thermal treatment on the optical performance of InGaN/GaN light emitting diodes

This paper describes a detailed analysis of the effects of high temperatures on the optical performance and structural characteristics of GaN-based LED structures with a high threading dislocation density. Results show that, as a consequence of storage at 900 \ub0C in N2 atmosphere, the samples exhibit: (i) an increase in the efficiency of GaN and quantum-well luminescence, well correlated to an increase in carrier lifetime; (ii) a decrease in the parasitic luminescence peaks related to Mg acceptors, which is correlated to the reduction in the concentration of Mg in the p-type region, detected by Secondary Ion Mass Spectroscopy (SIMS); (iii) a diffusion of acceptor (Mg) atoms to the quantum well region; (iv) a reduction in the yield of Rutherford Backscattering Spectrometry (RBS)-channeling measurements, possibly due to a partial re-arrangement of the dislocations, which is supposed to be correlated to the increase in radiative efficiency (see (i))