Sicurezza nei cantieri: analisi di rischio e condizioni di impiego di macchine operatrici e mezzi di sollevamento di materiali

Nel vasto quadro delle problematiche in materia di sicurezza nelle grandi opere di cantierizzazione, caratterizzate da alti livelli di meccanizzazione, la garanzia di adeguatezza delle macchine operatrici e delle attrezzature di sollevamento si pone certamente fra le esigenze prioritarie. La nota discute una tecnica di analisi e gestione del rischio coerente con le esigenze, logiche prima che normate, di rigore ed oggettività di analisi. Prendendo spunto da un approccio di provata efficacia, la tecnica consente di pervenire ad una verifica circa la sicurezza ed adeguatezza delle macchine allo impiego specifico, e può pertanto stabilire uno strumento utile agli analisti e ai tecnici degli Organi di Vigilanza, tanto in fase di scelte iniziali quanto in occasione di verifiche in corso d'opera. Un esempio di applicazione del metodo -seppure sviluppato per fronteggiare un problema contingente- conferma la validità generale della tecnica, a prescindere, come nel caso illustrato, dalla data di costruzione delle macchine in esame, e la sua efficacia anche quale riferimento per la identificazione di soluzioni di adeguamento realistiche e compatibili

Thermal transmittance in graphene based networks for polymer matrix composites

Graphene nanoribbons (GNRs) can be added as fillers in polymer matrix composites for enhancing their thermo-mechanical properties. In the present study, we focus on the effect of chemical and geometrical characteristics of GNRs on the thermal conduction properties of composite materials. Configurations consisting of single and triple GNRs are here considered as representative building blocks of larger filler networks. In particular, GNRs with different length, relative orientation and number of cross-linkers are investigated. Based on results obtained by Reverse Non-equilibrium Molecular Dynamics simulations, we report correlations relating thermal conductivity and thermal boundary resistance of GNRs with their geometrical and chemical characteristics. These effects in turn affect the overall thermal transmittance of graphene based networks. In the broader context of effective medium theory, such results could be beneficial to predict the thermal transport properties of devices made of polymer matrix composites, which currently find application in energy, automotive, aerospace, electronics, sporting goods, and infrastructure industries

Empirical analysis and classification of database errors in Scopus and Web of Science

In the last decade, a growing number of studies focused on the qualitative/quantitative analysis of bibliometric-database errors. Most of these studies relied on the identification and (manual) examination of relatively limited samples of errors. Using an automated procedure, we collected a large corpus of more than 10,000 errors in the two multidisciplinary databases Scopus and Web of Science (WoS), mainly including articles in the Engineering-Manufacturing field. Based on the manual examination of a portion (of about 10%) of these errors, this paper provides a preliminary analysis and classification, identifying similarities and differences between Scopus and WoS. The analysis reveals interesting results, such as: (i) although Scopus seems more accurate than WoS, it tends to forget to index more papers, causing the loss of the relevant citations given/obtained, (ii) both databases have relatively serious problems in managing the so-called Online-First articles, and (iii) lack of correlation between databases, regarding the distribution of the errors in several error categories. The description is supported by practical examples concerning a variety of errors in the Scopus and WoS database

Multi-Objective Reconfiguration of Radial Distribution Systems using Reliability Indices

This paper deals with the distribution network recon- figuration problem in a multi-objective scope, aiming to determine the optimal radial configuration by means of minimizing the active power losses and a set of commonly used reliability indices for- mulated with reference to the number of customers. The indices are developed in a way consistent with a mixed-integer linear pro- gramming (MILP) approach. A key contribution of the paper is the efficient implementation of the -constraint method using lexico- graphic optimization in order to solve the multi-objective optimiza- tion problem. After the Pareto efficient solution set is generated, the resulting configurations are evaluated using a backward/for- ward sweep load-flow algorithm to verify that the solutions ob- tained are both non-dominated and feasible. Since the -constraint method generates the Pareto front but does not incorporate deci- sion maker (DM) preferences, a multi-attribute decision making procedure, namely, the technique for order preference by simi- larity to ideal solution (TOPSIS) method, is used in order to rank the obtained solutions according to the DM preferences, facilitating the final selection. The applicability of the proposed method is as- sessed on a classical test system and on a practical distribution syste

Avvio e gestione di attività estrattive: un approccio in "Prevention Through Design"

Una efficace analisi e gestione dei rischi presso le unità estrattive, su cui fondare l'attività in coerenza con le norme vigenti in materia di sicurezza del lavoro, implica un approccio pro-attivo, tenuto conto dei diversi fattori coinvolti. In tale contesto un approccio pro-attivo richiede una approfondita analisi di rischio, fondata sulla valutazione delle possibili opzioni progettuali e la conoscenza del sito e del programma di coltivazione; nel presente lavoro viene esposta una metodologia basata su un sistema di registrazione dei dati tecnici supportata da un apposito software interattivo, in grado di aiutare la valutazione degli aspetti generali e specifici della sicurezza di comparto e di singole unità estrattive. Il lavoro è stato svolto dal Dipartimento di Ingegneria del Territorio, dell'Ambiente e delle Geotecnologie del Politecnico di Torino (già Autore di Linee Guida in materia di sicurezza per il comparto estrattivo) con il supporto dell'Ufficio Tutela Ambientale della Provincia di Torino

DTT device: Conceptual design of the superconducting magnet system

In the European Fusion Roadmap, one of the main challenges to be faced is the risk mitigation related to the impossibility of directly extrapolate to DEMO the divertor solution adopted in ITER, due to the very large loads expected. Thus, a satellite experimental facility oriented toward the exploration of robust divertor solutions for power and particles exhaust and to the study of plasma-material interaction scaled to long pulse operation, is currently being designed. Clearly, design requirements for this experiment are quite challenging, to account for the extreme operation conditions, which shall be as representative as possible of the DEMO ones, but in a much smaller device and at lower costs. A feasibility assessment has been carried out for the fully superconducting magnet system of the compact Divertor Tokamak Test (DTT) facility project. The overall magnet system is based on NbTi and Nb3Sn Cable-in-Conduit Conductors, and it adopts some of the most recent developments in this field. It consists of 18 Toroidal Field (TF), 6 Poloidal Field (PF) and 6 Central Solenoid (CS) module coils. In order to cope with the machine requirements such as plasma major and minor radii, magnetic field on plasma axis, plasma current, and inductive flux requirement, the Nb3Sn TF coil is characterized by a peak field of 11.4 T on the conductor, operating at 46.3 kA; the Nb3Sn CS modules are characterized by a peak field of about 13 T, with a conductor operating current of 23 kA; the PF coils are wound using NbTi conductors operating at a maximum peak field of 4.0 T, with operating currents in the range 21 kA to 25 kA, depending on the PF coil. Profiting of the compact machine size, and thus of relatively short conductor lengths, the TF coil winding pack is conceived as layer wound and made of two distinct sections, a low- and a high-field one, employing different superconductor cross-sections, and electrically connected through an embedded "ENEA-type" joint. The main features of the magnet system are described here; the results of mechanical, electrical and thermohydraulic analyses, which are discussed here, indicate that the proposed design fulfills all the required criteria. In addition, a brief description of the In-Vessel coils is given, though they are not superconducting, for the sake of completeness

Design of effective fins for fast PCM melting and solidification in shell-and-tube latent heat thermal energy storage through topology optimization

This paper presents a unique solution to the problem of heat transfer intensification in shell-and-tube latent heat thermal energy storage units by means of high conducting fins. We developed a design approach using topology optimization and multi-phase computational fluid dynamics. No assumption is made about the fins layout, which freely evolves along the optimization process resulting in more efficient non-trivial geometries. At each optimization iteration, the fluid-dynamic response in the phase change material is computed by solving the transient Navier-Stokes equations augmented with a phase-change porosity term. Coupling large design freedom to detailed physics modeling allowed studying the effect of convective transport on both design and performance of latent heat thermal storage units. Results indicate that accounting for fluid flow in design optimization studies is crucial for performance. It is shown that melting and solidification can be enhanced remarkably through natural convection by using well engineered fins with specific design features, that could hardly be revealed with alternative design routes. These features make designs optimized for melting fundamentally different from those optimized for solidification