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ϕ-Meson production at forward rapidity in p-Pb collisions at sNN=5.02 TeV and in pp collisions at s=2.76 TeV
No full textThe first study of phi-meson production in p-Pb collisions at forward and backward rapidity, at a nucleonnucleon centre-of-mass energy root s(NN)= 5.02 TeV, has been performed with the ALICE apparatus at the LHC. The phi-mesons have been identified in the dimuon decay channel in the transverse momentum (p(T)) range 1 < p(T) < 7GeV/c, both in the p-going (2.03 < y < 3.53) and the Pb-going (-4.46 < y < -2.96) directions - where ystands for the rapidity in the nucleon-nucleon centre-of-mass - the integrated luminosity amounting to 5.01 +/- 0.19nb(-1) and 5.81 +/- 0.20nb(-1), respectively, for the two data samples. Differential cross sections as a function of transverse momentum and rapidity are presented. The forward-backward ratio for f-meson production is measured for 2.96 <|y| < 3.53, resulting in a ratio similar to 0.5 with no significant p(T) dependence within the uncertainties. The p(T) dependence of the phi nuclear modification factor R-pPb exhibits an enhancement up to a factor 1.6 at p(T) = 3-4GeV/c in the Pb-going direction. The p(T) dependence of the f-meson cross section in pp collisions at root s= 2.76 TeV, which is used to determine a reference for the p-Pb results, is also presented here for 1 < pT< 5GeV/c and 2.5 < y < 4, for a 78 +/- 3nb(-1) integrated luminosity sample. (C) 2017 The Author(s). Published by Elsevier B.V
A.L.P.S ATELIER E LABORATORI PER IL PROGETTO SOSTENIBILE
No full textA.L.P.S ATELIER E LABORATORI PER IL PROGETTO SOSTENIBILE /MOUNTAINS/ HANGAR25 Mountains al Salone del Libro Off è un evento speciale del Salone dedicato tutto alla montagna con mostre, incontri, libri, film e eventi presso i nuovi spazi espostivi di Hangar 25 a Torino con di patrocinio di Regione Piemonte, Città metropolitana di Torino, Città di Torino, Città di Ivrea, UNCEM. La mostra A.L.P.S. Atelier e Laboratori per il Progetto Sostenibile, a cura di Daniele Regis, illustra le attività didattiche degli Atelier multidisciplinari "Riabitare le Alpi" del Corso di Laurea magistrale in Architettura per il progetto e le tesi di Laurea -dal Piemonte sud occidentale alla Carnia - su progetti di sviluppo sostenibile per le Alpi del Dipartimento Architettura e Design del Politecnico di Torino
Fatigue damage assessment of electric roads based on probabilistic load models
No full textThe electro-mobility is becoming an increasingly present reality in recent years. The most important drawback of this technology is known to be limited battery autonomy. In an attempt to overcome this problem, for specific studies and testing, a number of roads have been implemented with coil systems in order to transfer power to electric vehicles, as described in this article. While on the one hand this could solve the problem of charging, on the other hand the introduction of a technology within an existing infrastructure could result in further structural issues. Since little or no information on the possible structural effect of the introduction of a charging system in the road is currently available, this study has focused on the long-term fatigue analysis of an electric road infrastructure in which an inductive wireless charging system has been introduced into the road structure. To perform the fatigue analysis, a recursive procedure defined within a probabilistic framework was developed and applied to a benchmark case study. The results obtained from the analysis represent an initial database for the definition of strategies and protocols for the monitoring, maintenance and operations of future electric roads infrastructures
Arc Welding Processes: An Electrical Safety Analysis
No full textManual metal arc welding can be a hazardous practice if proper precautions are not taken. The welding procedure uses an open electric arc between an electrode and the metals to be joined. Besides the obvious risks of burns and inflammation of the cornea, which are prevented by using proper personal protective equipment, the operator may also be subject to the risk of electric shock from the exposed parts of the welding circuit, both the electrode and the workpiece. In addition, the welding current, by straying from the intended path, can cause localized heating of parts, with the risks of triggering fires and/or explosive atmospheres. Because of the high current required by the arc welding equipment, operators are exposed also to strong electromagnetic fields. This paper seeks to clarify the aforementioned issues, especially in light of the fact that the risk associated with electric shocks may be unknown to welders and their supervisors
Investigation and optimization of the performance of gravity water wheels
No full textWater wheels are rotating hydraulic machines that were introduced thousands of years ago to generate energy from water. Gravity water wheels are driven by the weight of the water flow and a portion of the flow kinetic energy. In the last decades, due to the increasing diffusion of micro hydropower plants (installed power less than 100 kW), gravity water wheels are being recognized as attractive hydraulic machines to produce electricity. Unfortunately, most of the engineering knowledge on water wheels is dated back to the XIX century, with several gaps and uncertainty. Additional work is still needed to fully understand the power losses and the performance within water wheels, that could lead to further improvements in efficiency. The scope of the present thesis is the investigation and improvement of the performance of gravity water wheels. This aim was achieved using physical experiments to quantify water wheels performance under different hydraulic conditions, theoretical models to estimate and predict the efficiency, and numerical simulations to optimize the design. Undershot, breastshot and overshot water wheels were investigated, in order to give a wide overview on all the kinds of gravity water wheels. Sagebien and Zuppinger undershot wheels were investigated at Southampton University, under the supervision of prof. Gerald Muller, from October 2015 until April 2016. These two wheels differ based on the shape of the blades. The blades of Sagebien wheels are optimized to reduce the inflow power losses, while those of Zuppinger wheels are conceived to minimize the outflow power losses. The objective of the experiments was to understand which of the two designs is better in term of efficiency. The tests showed that the Sagebien type exhibits a more constant efficiency as a function of the flow rate and the hydraulic head than the Zuppinger type. The maximum efficiency (excluding leakages) was identified as 88%. Breastshot water wheels were investigated experimentally, theoretically and using numerical Computational Fluid Dynamic (CFD) methods at Politecnico di Torino. The maximum experimental efficiency was estimated as 75% using a sluice gate inflow. A vertical inflow weir was also investigated, and found to have a more constant efficiency versus the rotational speed of the wheel, but with similar maximum values. A theoretical model that was developed to estimate the power output, power losses and efficiency, had a discrepancy with the experiments of 8%. A dimensionless law was also developed to estimate the power output. Numerical CFD simulations were performed to understand the effects of the number and shape of the blades on the efficiency. The optimal number of blades was 48 for the investigated wheel, and the efficiency can be improved using a circular shape. The numerical discrepancy with experiments was less than 6%. Overshot water wheels were investigated using a similar approach as done for breastshot wheels, and were found to have a maximum experimental efficiency of 85%. A theoretical model was developed to estimate the power losses and the efficiency, in particular to quantify the volumetric losses at the top of the wheel, that is the fraction of the flow which can not enter into the buckets and that is lost. Then, numerical simulations will be started to try to improve the wheel efficiency, reducing the previous volumetric losses. More specifically, a circular wall around the periphery of the wheel was added to the original design, leading to a performance improvement up to 60%. The results of this work show that water wheels can be considered attractive hydropower converters
Oxygen evolution catalysis in alkaline conditions over hard templated nickel-cobalt based spinel oxides
No full textIn this work, two series of cobalt-based spinel catalysts, Co3O4 and NiCo2O4, were synthesised by a hard template method with SBA-15 and were investigated as non-noble catalysts for the oxygen evolution reaction (OER) under basic conditions. The effect of synthesis conditions, i.e., heating rate and calcination temperature, and the addition of minor amounts of iron were evaluated with respect to the OER activity. Moreover, the influence of the alkali cation type in the electrolyte (Li, Na, K) was also evaluated. The highest activity was found for the NiCo2O4 obtained with the lowest heating rate. The increase in the heating rate and calcination temperature results in the decrease of the available surface area for the reaction, leading to the deterioration of the activity. The incorporation of 3 wt.% of iron in the lattice of NiCo2O4 and Co3O4 resulted in a decrease of the OER activity, however, the deactivation was much less severe in the case of NiCo2O4 than for Co3O4. Among the alkaline electrolytes used, KOH resulted in the highest catalytic activity both for NiCo2O4 and Co3O4
Weak Localization in Electric-Double-Layer Gated Few-layer Graphene
No full textWe induce surface carrier densities up to ~ 7 x 10^14 cm^(-2) in few-layer graphene devices by electric double layer gating with a polymeric electrolyte. In 3-, 4- and 5-layer graphene below 20-30K we observe a logarithmic upturn of resistance that we attribute to weak localization in the diffusive regime. By studying this effect as a function of carrier density and with ab-initio calculations we derive the dependence of transport, intervalley and phase coherence scattering lifetimes on total carrier density. We find that electron-electron scattering in the Nyquist regime is the main source of dephasing at temperatures lower than 30K in the ~ 10^13 cm^(-2) to ~ 7 x 10^14 cm^(-2) range of carrier densities. With the increase of gate voltage, transport elastic scattering is dominated by the competing effects due to the increase in both carrier density and charged scattering centers at the surface. We also tune our devices into a crossover regime between weak and strong localization, indicating that simultaneous tunability of both carrier and defect density at the surface of electric double layer gated materials is possible
Douglas-Gunn Method Applied to Dosimetric Assessment in Magnetic Resonance Imaging
No full textThe Douglas-Gunn method has been applied to the solution of Pennes' bioheat equation to estimate the heating of bulk metallic prostheses caused by the energy deposition due to the gradient magnetic field of a magnetic resonance imaging (MRI) scanner. The proposed method has been implemented to work on a graphic processing unit and the accuracy and numerical efficiency has been compared with the explicit Euler scheme. As an example of application, the heating of a realistic hip prosthesis during the execution of a 3-D true fast imaging with steady precession MRI sequence has been finally evaluated
Patrimoni religiosi: temi "antichi" per strategie nuove di gestione e valorizzazione
No full textI temi della valorizzazione e in particolare della gestione dei patrimoni -nello specifico storici e di grandi entità- è di forte attualità, in particolare a partire da una stagione di provvedimenti legislativi a carattere nazionale e internazionale (Codice Beni Culturali, provvedimenti "Sistema Paese" sui Beni demaniali, accento sul "Riuso" dei patrimoni storici da parte di enti nazionali quali il CNAPPC, ecc.) che, almeno sulla carta, li hanno individuati come temi centrali. I momenti non solo del loro censimento, conoscenza e messa in efficienza, ma anche quello del loro mantenimento nel tempo e della loro gestione vedono come fase centrale quella della individuazione della funzione, compatibile con le caratteristiche degli edifici e con quelle dei contesti. Ragionamenti ormai consolidati per la categoria dei beni culturali -in particolare pubblici e demaniali e ancor più per le funzioni museali- che, se trasferiti al segmento del patrimonio architettonico religioso, aprono spazi di ricerca e di sperimentazione con caratteri di innovazione e originalità. In particolare, due i temi specifici di indagine che si vogliono illustrare nel dettaglio per futuri sviluppi di ricerca nel seno delle discipline estimativo-gestionali: 1. in ottica INSPIRE, l'interoperabilità delle banche dati conoscitive del patrimonio religioso, richiesta dagli standard internazionali di catalogazione (ICCD), con attenzione sui metadati relativi alla natura giuridica dei proprietari, gestori, concessionari, ecc., alla natura vincolistica (ove presente), allo stato di conservazione, ai costi parametrici d'investimento e di manutenzione; 2. il monitoraggio delle attività e la loro gestione in termini di efficacia ed efficienza, in una logica "di qualità", secondo gli indicatori e gli standard testati a livello internazionale -nel campo museale- nei processi di accreditamento. Tali declinazioni, apparentemente settoriali, se analizzate consapevolmente nelle fasi preliminari agli interventi di adeguamento e/o trasformazione, hanno delle ricadute significative nelle strategie di valorizzazione dei patrimoni, consentendo di avere un quadro analitico -ancorchè complesso- su cui individuare un elenco di priorità di intervento, per la quantificazione parametrica delle risorse finanziarie da investire e da ricercare secondo le attuali tecniche del fundraising