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Sant'Ambrogio di Torino, Italy

Cattani A.,Corso Duca degli Abruzzi
Mathematical Biosciences and Engineering

The aim of this work is to investigate the dynamics of a neural network, in which neurons, individually described by the FitzHugh-Nagumo model, are coupled by a generalized diffusive term. The formulation we are going to exploit is based on the general framework of graph theory. With the aim of defining the connection structure among the excitable elements, the discrete Laplacian matrix plays a fundamental role. In fact, it allows us to model the instantaneous propagation of signals between neurons, which need not be physically close to each other. This approach enables us to address three fundamental issues. Firstly, each neuron is described using the well-known FitzHugh-Nagumo model which might allow to differentiate their individual behaviour. Furthermore, exploiting the Laplacian matrix, a well defined connection structure is formalized. Finally, random networks and an ensemble of excitatory and inhibitory synapses are considered. Several simulations are performed to graphically present how dynamics within a network evolve. Thanks to an appropriate initial stimulus a wave is created: it propagates in a self-sustained way through the whole set of neu- rons. A novel graphical representation of the dynamics is shown. Source

Ferraris M.,Institute of Materials Physics and Engineering | Salvo M.,Institute of Materials Physics and Engineering | Casalegno V.,Institute of Materials Physics and Engineering | Avalle M.,Corso Duca degli Abruzzi | Ventrella A.,Institute of Materials Physics and Engineering
International Journal of Applied Ceramic Technology

The results of an experimental investigation on epoxy-joined silicon carbide tested in shear mode by four different configurations of torsion test are presented and compared to results obtained by asymmetric four-point bending and four different lap tests in compression. All samples have been joined by an epoxy adhesive (Araldite AV119) which is to be considered as a model brittle joining material chosen to obtain several joined samples in a reasonable time. Advantages and disadvantages of each configuration are discussed and compared to results previously obtained with epoxy-joined Carbon/Carbon composites and ceramics tested with the same methods. © 2012 American Ceramic Society. Source

Cardu M.,Polytechnic University of Turin | Iabichino G.,Corso Duca degli Abruzzi | Oreste P.,Polytechnic University of Turin | Rispoli A.,University of Turin
Acta Geotechnica

The use of tunnel boring machines (TBMs) is increasingly popular in tunnelling. One of the most important aspects in the use of these machines is to assess with certain accuracy the effectiveness of the action of the discs on the cutter-head in the different rock types to be excavated. A specific machine, called an intermediate linear cutting machine (ILCM), has been developed at the Politecnico di Torino in order to study, on a reduced scale in detail in the laboratory, the interaction between the discs of the TBM and the rock: this machine allows a series of grooves to be cut on a rock sample of 0.5 × 0.3 × 0.2 m, through the rolling of a 6.5-in. disc, and evaluation, during testing, of the parameters associated with the action of the cutting tool. The parameters measured during the tests were compared with the results obtained employing two analytical methods widely used for predicting the performance of TBMs: the Colorado School of Mines (CSM) model and the Norwegian University of Science and Technology (NTNU) model. The latter showed a greater ability to reproduce tests conducted using the ILCM. However, as with the CSM model, it does not allow the optimal excavation condition (the ratio, which minimizes the specific energy of excavation, between the groove spacing and the penetration of the disc), necessary for the correct design of the TBM cutter-head, to be identified. An example, based on a real case of a tunnel in Northern Italy, allowed a demonstration of how the NTNU model provides results in line with the measurements taken during the excavation and represents, therefore, a model that is able to reliably simulate both laboratory tests and the action of a TBM on site. The NTNU model, together with the results of the tests with ILCM targeted on the identification of the optimal conditions of excavation, may allow the correct dimensioning of the TBM cutter-head to be attained in order to effectively implement the excavation. © 2016 Springer-Verlag Berlin Heidelberg Source

Ahmad M.,DAppolonia S.p.A. | Demichela M.,Corso Duca degli Abruzzi | Leva M.C.,College Green
30th Center for Chemical Process Safety International Conference 2015 - Topical Conference at the 2015 AIChE Spring Meeting and 11th Global Congress on Process Safety

This paper presents a statistical analysis of past accidents that occurred between 1988 and 2012 reported to the European Commission's Major Accident Reporting System (eMARS) focusing on human and organizational factor (HOF) assessment. The main purpose of this analysis is to provide guidelines for the HOF analysis and its quantification for accident risk assessment in chemical process industries. In this analysis both operational and diagnostic layers are considered with respect to human actions. For the purpose of this analysis, five identified organizational factors have been selected as Performance Shaping Factors (PSF) for human actions/interventions. The SPAR- H model has been applied to evaluate the affect of PSFs on the human reliability. The overall framework has been modeled by using a newly developed approach, the Method for Error Deduction and Incident Analysis (MEDIA). In MEDIA new HOF action- based taxonomies have also been developed. By using a score method it is possible to identify the most critical PSF for human reliability, which should be improved in order to improve the overall human reliability. Copyright © (2015) by AIChE All rights reserved. Source

Smeacetto F.,Polytechnic University of Turin | Salvo M.,Polytechnic University of Turin | D'Herin Bytner F.D.,Polytechnic University of Turin | Leone P.,Corso Duca degli Abruzzi | Ferraris M.,Polytechnic University of Turin
Journal of the European Ceramic Society

This work describes the design of three new glass and glass ceramic compositions to join the ceramic electrolyte (YSZ wafer) to the metallic interconnect (Crofer22APU) in planar SOFC stacks. The designed sealants are low-sodium, barium free and boron-oxide free silica-based glasses. The sealing process was optimized for the most promising composition and joined Crofer22APU/glass-ceramic sealant/YSZ samples were morphologically characterized and tested for 300 h in humidified hydrogen atmosphere at the fuel cell operating temperature of 800 °C. The study showed that the use of the glass-ceramic was successful in joining the YSZ ceramic electrolyte to the Crofer22APU metallic interconnect and in preventing severe corrosion effects at the Crofer22APU/glass-ceramic interface after static treatments in humidified hydrogen at 800 °C for 300 h. © 2009 Elsevier Ltd. All rights reserved. Source

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