Analisi delle prestazioni di elettrolizzatori tipo PEM

Le fonti di energia rinnovabili rappresentano una forma di energia indispensabile al sostentamento dell’attuale sistema produttivo mondiale. L’energia eolica e fotovoltaica ricoprono un ruolo fondamentale nel panorama rinnovabile, e portano con se l’inevitabile svantaggio derivato dall’impossibilita di controllare la fonte primaria di energia. I sistemi di accumulo ed immagazzinamento di energia assumeranno un ruolo strategico nel prossimo scenario energetico, in particolare nell’elaborato viene posta l’attenzione sui sistemi Power-to-Gas. La tecnologia Power-to-Gas consente di produrre gas ad alta potenza specifica (idrogeno o metano sintetico), usando elettricità proveniente da fonti rinnovabili. L’elettrolisi è il metodo più efficiente per convertire energia elettrica in idrogeno. Tra le varie tecnologie, gli elettrolizzatori di tipologia PEM (Proton Exchange Membrane), sono considerati i più adatti all’accoppiamento con fonti di energia rinnovabile, per via della loro risposta alle variazioni di carico e dell’ampio campo di funzionamento. Il lavoro di tesi si concentra sull’analisi delle prestazioni di elettrolizzatori tipo PEM, ed in particolare sull’elettrolizzatore inserito all’interno del “Laboratorio di Microreti di Generazione ed Accumulo” del Tecnopolo di Ravenna. Il laboratorio ha lo scopo di studiare e testare sistemi per la produzione di energia elettrica da fonte rinnovabile e per l’accumulo. L’impianto è costituito principalmente da due pannelli fotovoltaici con il compito di produrre energia, due batterie per accumulare l’energia prodotta dai pannelli, un elettrolizzatore e tre bombole a idruri metallici per lo stoccaggio di idrogeno. Dai dati sperimentali ottenuti dalle prove in laboratorio si è ricavato un modello matematico black-box dell’elettrolizzatore. Il modello gestisce le equazioni della curva caratteristica (P;η). In seguito il modello ottenuto è stato confrontato con un caso analogo presente in letteratura.

From trust who to trust what. A fresh perspective on trust in the era of blockchain

In the last few years, a remarkable technological revolution has been taking place around the world. Such a technological revolution is not just a means to the end of improving efficiency, but an important end of social order. In this work, I show that blockchain is one important example. I discuss that the success of a disintermediated transaction is conditioned on the level of trust in the rules-of-code. In what follows, the dissertation is organized in three studies. Study 1 is a theoretical paper where I present and discuss a model of how blockchain-like technologies can automate and algorithmically dictate the nurturing of trust. Based on study 1, study 2 is aimed to develop and validate a quantitative scale to measure each component of the proposed trust model. Lastly, study 3 is intended to investigate how telematic equipment can affect individual trusting behavior under condition of information asymmetry. The introduction of black box in the Italian automobile insurance market is the set of this study. Overall, the dissertation offers some major contributions for theory and practice about the dynamics underlying the development of trust in the rising era of blockchain transactions.

Intervista camminata e altri metodi qualitativi per monitorare l'efficacia dei progetti di Educazione Avventura con adolescenti a rischio

INTRODUZIONE - La presente ricerca è incentrata sul monitoraggio dell’efficacia dei progetti di Educazione Avventura con adolescenti difficili, in particolare del progetto “Lunghi cammini educativi”. A partire da un’analisi della letteratura sull’educazione esperienziale nature-based e in particolare sull’Adventure Education con adolescenti difficili, è stata progettata una rilevazione empirica attraverso cui sperimentare un metodo di monitoraggio finalizzato a cogliere la dimensione processuale (che nella ricerca nell’ambito resta spesso inesplorata, poiché sono maggiormente diffusi i metodi di monitoraggio cosiddetti “black-box”), utilizzando un sistema integrato di diverse tecniche di rilevazione. Le due principali domande che hanno guidato la ricerca sono state: 1.Quali processi educativi significativi si innescano e possono essere osservati durante l’esperienza? 2.Il metodo dell’intervista camminata, integrato ad altri metodi, è utile per individuare e monitorare questi processi? METODO - Collocandosi all’interno di un framework metodologico qualitativo (influenzato da riflessioni post-qualitative, paradigma delle mobilità e sguardo fenomenologico), la ricerca prende la forma di uno studio di caso singolo con due unità di analisi, e prevede la triangolazione di diversi metodi di raccolta dei dati: analisi documentale; osservazione partecipante nei cammini e nelle riunioni di équipe; interviste (prima, durante, dopo il cammino) con differenti tecniche: camminata, “image-elicited”, tradizionale, online. RISULTATI - L’analisi tematica abduttiva delle interviste e delle osservazioni conferma quanto già evidenziato dalla letteratura circa la centralità della dilatazione del campo d’esperienza e del lavoro su alcune life skills (in particolare, competenze personali e growth mindset). Emergono anche alcuni key findings inattesi: il notevole “peso” dello stile educativo dell’accompagnatore; la “scoperta” del ruolo della quotidianità all’interno dell’esperienza straordinaria; la necessità di consapevolezza riguardo al potenziale educativo dell’ambiente (naturale e/o antropizzato), per una maggiore intenzionalità nelle scelte strategiche di cammino. L’intervista camminata, nonostante alcuni limiti, si conferma come metodo effettivamente utile a cogliere la dimensione processuale, e coerente con il contesto indagato.

Registratore di dati di evento (EDR). Regolamento europeo 2019/2144 e caso studio.

Il numero dei decessi per incidenti stradali nel mondo continua ad aumentare secondo ritmi preoccupanti, così come anche il numero dei feriti e i conseguenti costi sociali legati al fenomeno. In Europa, e più in generale nei paesi ad alto reddito, il progresso tecnologico e le azioni legislative hanno permesso di raggiungere importanti successi nel miglioramento della sicurezza stradale con conseguente riduzione del numero dei decessi. Purtroppo però, i numeri testimoniano come ci sia ancora molta strada da percorrere. In questa tesi vengono presentate numerose statistiche aggiornate sul fenomeno dell’incidentalità stradale e vengono analizzate le azioni intraprese a livello europeo volte al raggiungimento degli obbiettivi internazionali ed europei fissati per il 2030 ed il 2050. Viene poi analizzato nel dettaglio il recente Regolamento Europeo 2019/2144 con particolare riferimento al Registratore di Dati di Evento (EDR) rientrante tra gli Advanced Driver Assistance Systems (ADAS) resi obbligatori dallo stesso Regolamento Europeo 2019/2144. A tal proposito viene illustrato, tramite un caso studio verificatosi in Emilia-Romagna, come un dispositivo EDR possa essere utilizzato efficacemente per ricostruire la dinamica di un sinistro stradale.

Semiclassical approach to black hole absorption of electromagnetic radiation emitted by a rotating charge

We consider an electric charge, minimally coupled to the Maxwell field, rotating around a Schwarzschild black hole. We investigate how much of the radiation emitted from the swirling charge is absorbed by the black hole and show that most of the photons escape to infinity. For this purpose we use the Gupta-Bleuler quantization of the electromagnetic field in the modified Feynman gauge developed in the context of quantum field theory in Schwarzschild spacetime. We obtain that the two photon polarizations contribute quite differently to the emitted power. In addition, we discuss the accurateness of the results obtained in a full general relativistic approach in comparison with the ones obtained when the electric charge is assumed to be orbiting a massive object due to a Newtonian force.

Non-planar double-box, massive and massless pentabox Feynman integrals in the negative-dimensional approach

The negative-dimensional integration method is a technique which can be applied, with success, in usual covariant gauge calculations. We consider three two-loop diagrams: the scalar massless non-planar double-box with six propagators and the scalar pentabox in two cases, where six virtual particles have the same mass, and in the case all of them are massless. Our results are given in terms of hypergeometric functions of Mandelstam variables and also for arbitrary exponents of propagators and dimension D.

Sudan Black B treatment reduces autofluorescence and improves resolution of in situ hybridization specific fluorescent signals of brain sections

Interference by autofluorescence is one of the major concerns of immunofluorescence analysis of in situ hybridization-based diagnostic assays. We present a useful technique that reduces autofluorescent background without affecting the tissue integrity or direct immunofluorescence signals in brain sections. Using six different protocols, such as ammonia/ethanol, Sudan Black B (SBB) in 70% ethanol, photobleaching with UV light and different combinations of them in both formalin-fixed paraffin-embedded and frozen human brain tissue sections, we have found that tissue treatment of SBB in a concentration of 0.1% in 70% ethanol is the best approach to reduce/eliminate tissue autofluorescence and background, while preserving the specific fluorescence hybridization signals. This strategy is a feasible, non-time consuming method that provides a reasonable compromise between total reduction of the tissue autofluorescence and maintenance of specific fluorescent labels.

Modeling of phase equilibrium and vapor adsorption on carbon black based on a combination of a lattice theory and equation of state

A thermodynamic approach is developed in this paper to describe the behavior of a subcritical fluid in the neighborhood of vapor-liquid interface and close to a graphite surface. The fluid is modeled as a system of parallel molecular layers. The Helmholtz free energy of the fluid is expressed as the sum of the intrinsic Helmholtz free energies of separate layers and the potential energy of their mutual interactions calculated by the 10-4 potential. This Helmholtz free energy is described by an equation of state (such as the Bender or Peng-Robinson equation), which allows us a convenient means to obtain the intrinsic Helmholtz free energy of each molecular layer as a function of its two-dimensional density. All molecular layers of the bulk fluid are in mechanical equilibrium corresponding to the minimum of the total potential energy. In the case of adsorption the external potential exerted by the graphite layers is added to the free energy. The state of the interface zone between the liquid and the vapor phases or the state of the adsorbed phase is determined by the minimum of the grand potential. In the case of phase equilibrium the approach leads to the distribution of density and pressure over the transition zone. The interrelation between the collision diameter and the potential well depth was determined by the surface tension. It was shown that the distance between neighboring molecular layers substantially changes in the vapor-liquid transition zone and in the adsorbed phase with loading. The approach is considered in this paper for the case of adsorption of argon and nitrogen on carbon black. In both cases an excellent agreement with the experimental data was achieved without additional assumptions and fitting parameters, except for the fluid-solid potential well depth. The approach has far-reaching consequences and can be readily extended to the model of adsorption in slit pores of carbonaceous materials and to the analysis of multicomponent adsorption systems. (C) 2002 Elsevier Science (USA).

Pasture grazing by black-striped wallabies (Macropus dorsalis) in central Queensland

Black-striped wallabies (Macropus dorsalis) are uncommon to rare in most of their former range, yet in parts of central Queensland where they are still locally common they are regarded as a serious pasture pest. There is considerable pressure from cattle graziers to reduce their density because of the putative damage that they cause to cattle pasture. Here we examined the effects of this species and other herbivores on pasture by monitoring vegetation cover between 1993 and 1998 in exclosures in brigalow, and poplar box communities on three grazing properties in the Maranoa region. The exclosures selectively allowed access to either: all vertebrate grazers including cattle; rabbits, bettongs, and wallabies; rabbits and bettongs; no vertebrate grazers. The greatest effects on the structure and species composition of pasture were caused by cattle, but wallabies did consume commercially important quantities of grass at some times of the year. This conflicts with local opinion that sees wallabies as the major cause of pasture degradation. Herein lies the management problem that sees continued reduction in wallaby habitat, and fragmentation of the species.

Constructing the National Canon in Ireland and Macedonia: The Function of Folklore in the Plays The Countess Cathleen and The Land of Heart’s Desire by William Butler Yeats, and Proud Flesh and The Black Hole by Goran Stefanovski and Their Role in Strengthening National Identity

Erasmus Mundus Masters “Crossways in European Humanities” June 2011

Renova black toilet paper: The creation of a glocal market space

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics

Description of continuous data using bar graphs: a misleading approach

INTRODUCTION:With the ease provided by current computational programs, medical and scientific journals use bar graphs to describe continuous data.METHODS:This manuscript discusses the inadequacy of bars graphs to present continuous data.RESULTS:Simulated data show that box plots and dot plots are more-feasible tools to describe continuous data.CONCLUSIONS:These plots are preferred to represent continuous variables since they effectively describe the range, shape, and variability of observations and clearly identify outliers. By contrast, bar graphs address only measures of central tendency. Bar graphs should be used only to describe qualitative data.

Detection of road accident accumulation zones with a visual analytics approach

Nowadays, road accidents are a major public health problem, which increase is forecasted if road safety is not treated properly, dying about 1.2 million people every year around the globe. In 2012, Portugal recorded 573 fatalities in road accidents, on site, revealing the largest decreasing of the European Union for 2011, along with Denmark. Beyond the impact caused by fatalities, it was calculated that the economic and social costs of road accidents weighted about 1.17% of the Portuguese gross domestic product in 2010. Visual Analytics allows the combination of data analysis techniques with interactive visualizations, which facilitates the process of knowledge discovery in sets of large and complex data, while the Geovisual Analytics facilitates the exploration of space-time data through maps with different variables and parameters that are under analysis. In Portugal, the identification of road accident accumulation zones, in this work named black spots, has been restricted to annual fixed windows. In this work, it is presented a dynamic approach based on Visual Analytics techniques that is able to identify the displacement of black spots on sliding windows of 12 months. Moreover, with the use of different parameterizations in the formula usually used to detect black spots, it is possible to identify zones that are almost becoming black spots. Through the proposed visualizations, the study and identification of countermeasures to this social and economic problem can gain new grounds and thus the decision- making process is supported and improved.