Large deformation numerical assessment of rock anchor response under axial loading for offshore renewable energy applications

The study presented in this paper aims to advance the current understanding of Rock Anchor (RA) performance under axial loading through large deformation numerical analyses. Simulations are conducted using the Geotechnical Particle Finite Element Method within a coupled hydro-mechanical framework. Experimental data from the literature is used to calibrate a strain hardening plasticity constitutive model for rocks. The calibrated model is then used to investigate rate effects on the axial response of a novel rock anchor design. The axial pullout induces rock dilatation at the bottom edge of the anchor with the consequent formation of a zone of negative water pressure change and a bulb of positive pore water pressure change above it. Depending on the pullout rate, distinct drained, partially drained, and undrained hydraulic regimes are identified. These, along with the variable damage distributions, are shown to influence the rock anchor axial capacity considerably. The geometrical and elastic properties of the rock anchor modelled as a deformable body, along with the interface friction angle between the anchor and the rock are also explored. Results such as load capacity curves, stress path evolutions, and stress distributions on the rock-rock anchor interface are analysed emphasizing their impact on rock anchor design

The enhancement of excitonic emission crossing Saha equilibrium in trap passivated CH3NH3PbBr3 perovskite

Metal-halide semiconductor perovskites have received great attention for the development of stable and efficient light emitting diodes and lasers, since they combine high charge carrier mobility and light emission spectral-purity with low-cost fabrication methods. Nevertheless, the role of excitons, free carries and trap states in perovskite light emission properties is still unclear due to their interdependence. In this paper we selectively manage trapping and light emission mechanisms by a reversible laser-assisted trap-passivation process performed on a CH3NH3PbBr3 perovskite layer, coupled to the inner modes of a high-quality micro-cavity, which only affects the radiative recombination. We show that photoluminescence is dominated by exciton radiative decay process and that trap states passivation increases the exciton gemination rate by reducing coulombic scattering of free electrons due to the ionized impurities. This picture provides a more general description than the model based on trap states-free Saha thermodynamic equilibrium between photo-generated species. The interdependence of free carries, trap states and excitons in the light emission properties of CH3NH3PbBr3 perovskite thin films and their relationship to device performance is a subject of debate. Here, the authors investigate the role of non-radiative recombination and demonstrate that the photoluminescence is dominated by exciton radiative decay processes

Tracking dynamics of magma migration in open-conduit systems

Open-conduit volcanic systems are typically characterized by unsealed volcanic conduits feeding permanent or quasi-permanent volcanic activity. This persistent activity limits our ability to read changes in the monitored parameters, making the assessment of possible eruptive crises more difficult. We show how an integrated approach to monitoring can solve this problem, opening a new way to data interpretation. The increasing rate of explosive transients, tremor amplitude, thermal emissions of ejected tephra, and rise of the very-long- period (VLP) seismic source towards the surface are interpreted as indicating an upward migration of the magma column in response to an increased magma input rate. During the 2014 flank eruption of Stromboli, this magma input pre- ceded the effusive eruption by several months. When the new lateral effusive vent opened on the Sciara del Fuoco slope, the effusion was accompanied by a large ground deflation, a deepening of the VLP seismic source, and the cessation of summit explosive activity. Such observations suggest the drainage of a superficial magma reservoir confined between the crater terrace and the effusive vent. We show how this model successfully reproduces the measured rate of effusion, the observed rate of ground deflation, and the deepening of the VLP seismic source. This study also demonstrates the ability of the geophysical network to detect superficial magma recharge within an open-conduit system and to track magma drainage during the effusive crisis, with a great impact on hazard assessment

A Correlated Double Sampling Technique for Charge-Sensitive Amplifiers based on TFTs

In this work is presented a low-noise Charge Sensitive Amplifier (CSA) suitable for the readout of high-impedance pyroelectric sensors. The circuit exploits a novel Correlated Double Sampling (CDS) technique which allows both continuous-time integration and cancellation of the Thin-Film Transistor (TFT) 1/f noise. The CSA has been implemented in a printed unipolar Organic TFT technology and simulation results demonstrate a Signal-to-Noise Ratio (SNR) improvement of approximately 10 dB when the proposed CDS technique is applied at the frequency of 500 Hz. This result is expected e.g., to extend the proximity detection range and improve the safety in human-machine applications using large-area infrared-sensing surfaces. Moreover, the proposed technique can be used in generic Analog Frontend Electronics embedding switched capacitor amplifiers, to suppress correlated noise sources

I Nuovi strumenti finanziari delle società cooperative: verso il mercato dei capitali?

La riforma del diritto delle societa` di capitali (D.Lgs. n. 6/2003) ha introdotto innovazioni estremamente rilevanti nella disciplina delle cooperative, con particolare riguardo al tema del finanziamento dell’impresa, che pone problemi del tutto peculiari in questa forma di societa`. Di seguito si esamineranno, nella prospettiva economico-finanziaria ed in quella societaria, alcuni aspetti specifici che rivestono una particolare importanza rispetto al rapporto con il mercato dei capitali

A colour tunable microcavity by weak-to-strong coupling regime transition through a light-switchable material

An organic based microcavity showing fully reversible colour tunability has been achieved for the first time. The emission output changes according to the modulation from pure photonic to polaritonic resonant modes through UV irradiation of the light-switchable matrix