Dipartimento di Fisica - Tesi di Dottorato
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Questa collezione raccoglie le Tesi di Dottorato afferenti al Dipartimento di Fisica dell'Università della Calabria.
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Item Applicazione dei big data nel turismo, marketing ed education(Università della Calabria, 2020-03-18) Giglio, Simona; Critelli, Salvatore; Pantano, PietroIl mondo è attualmente inondato da dati e l’avanzare delle tecnologie digitali amplifica questo fenomeno in modo esponenziale. Tale fenomeno viene etichettato con il concetto di Big Data ovvero le tracce digitali che le nostre attività quotidiane lasciano per effetto dell’uso massiccio dei sistemi ICT (Information Communication Technologies). I Big Data sono diventati il nuovo microscopio che rende “misurabile” la società. Per tali ragioni, la ricerca è incentrata sull’analisi dei Big data, estratti dai social media, da indagini online, da piattaforme di recensioni e da database, attraverso l’applicazione di tecniche e strumenti sviluppati nell’ambito dell’Intelligenza Artificiale. Algoritmi di machine learning, analisi semantica ed analisi statistica sono stati utilizzati per estrarre, dai Big Data, informazione sotto forma di “conoscenza” e “valore”, dimostrando come dati di grandi dimensioni possano fungere da ricca fonte di informazione, da un lato, per comprendere il comportamento dell’utente, parte integrante di una società complessa (conoscenza), e dall’altro, per sostenere i processi decisionali e i servizi forniti agli utenti/consumatori (valore). Il lavoro si caratterizza per un approccio multidisciplinare tra settori differenti quali le scienze sociali, le scienze statistiche e l’informatica. Questo ha permesso di fondare la ricerca sui Big Data nella teoria, e fornire un efficace recupero e analisi dei dati nella pratica. Le tecniche di machine learning sono state applicate per (i) il riconoscimento delle immagini, (ii) per la creazione di cluster, (iii) per l’analisi del testo (sentiment analysis) e (iv) per la profilazione di classi di utenti. Per il riconoscimento delle immagini l’approccio ha richiamato le reti neurali artificiali (deep artificial neural networks), algoritmi e sistemi computazionali ispirati al cervello umano utilizzando le potenzialità del programma Wolfram Mathematica e la disponibilità di dati estratti da social network quali Flickr, Twitter, Instagram ed altre piattaforme come TripAdvisor. Gli strumenti utilizzati nella ricerca hanno permesso di indagare e di rilevare in modo oggettivo dall’analisi di immagini e di testi condivisi sul web, alcuni comportamenti cognitivi degli utenti/consumatori alla base delle loro scelte nonché l’attrattività di una destinazione turistica e la qualità dell’esperienza dell’utente. Lo studio del significato delle parole nel testo ha aperto la strada al web semantico che permette ad un utente di acquisire informazioni approfondite durante una ricerca attraverso un sistema formato da una rete di relazioni e connessioni tra documenti. Partendo dalle ricerche di Ogden e Richards sullo studio del significato e di Jakobson che studiò i processi comunicativi, si è cercato di strutturare e sistematizzare un processo che riflette un atto comunicativo ed informativo tale che un simbolo (immagine) attraverso l’applicazione di un significante (machine learning che si sostituisce al processo mentale proprio dell’uomo) permettesse l’esplicitazione di un referente (oggetto\etichetta) che opportunatamente porta alla trasmissione di un messaggio sotto forma di conoscenza. Il tutto coordinato da un sistema in grado di coniugare fattori differenti in un’ottica interdisciplinare dove l’analisi dei dati combacia perfettamente con la linguistica. Attingendo da studi precedenti, i risultati raggiunti dimostrano che gli algoritmi di analisi dei Big Data quali l’apprendimento automatico contribuiscono da un lato alla comprensione sull’esperienza dell’utente verso un luogo, una destinazione; d’altra parte, la loro analisi fornisce una conoscenza sistematica delle valutazioni dei consumatori su un determinato prodotto o servizio e verso lo sviluppo di una sorta di “intelligenza sociale”. Inoltre i risultati della ricerca propongono come, un approccio più sofisticato al monitoraggio dei social media nel contesto turistico e nel marketing, nonché nel settore dell’education, possa contribuire a migliorare le decisioni strategiche e le politiche operative degli stakeholder nonché ad avere una visione psicologica sugli atteggiamenti e sul comportamento di un ampio spettro di utenti.Item Nano materials and innovative laser-based accelerators for cultural heritage(2017-07-12) Veltri, Simona; Pantano, Pietro; Bonanno, Assunta; Antici, PatrizioUniversità della Calabria, Dipartimento di FisicaItem Nano materials and innovative laser-based accelerators for cultural heritage(2017-07-12) Veltri, Simona; Pantano, Pietro; Bonanno, Assunta; Antici, PatrizioItem Charged-particle distributions and material measurements in ps = 13 TeV pp collisions with the ATLAS Inner Detector(2017-07-14) Cairo, Valentina Maria Martina; Pantano, Pietro; Dell'Acqua, Andrea; Schioppa, MarcoThe Run 2 of the Large Hadron Collider, which began in Spring 2015, offers new challenges to the Experiments with its unprecedented energy scale and high luminosity regime. To cope with the new experimental conditions, the ATLAS Experiment was upgraded during the first long shutdown of the collider, in the period 2013-2014. The most relevant change which occurred in the ATLAS Inner Detector was the installation of a fourth pixel layer, the Insertable B-Layer, at a radius of 33 mm together with a new thinner beam pipe. The Pixel Services, located between the Pixel and SCT detectors, were also modified. Owing to the radically modified ID layout, many aspects of the track reconstruction programs had to be re-optimized. In this thesis, the improvements to the tracking algorithms and the studies of the material distribution in the Inner Detector are described in detail, together with the improvements introduced in the geometry model description in simulation as well as the re-evaluation and the reduction of the systematic uncertainty on the estimate of the track reconstruction efficiency. The results of these studies were applied to the measurement of Charged-Particle Multiplicity in proton–proton collisions at a centre-of-mass energy of 13 TeV. The chargedparticle multiplicity, its dependence on transverse momentum and pseudorapidity and the dependence of the mean transverse momentum on the charged-particle multiplicity are presented for various fiducial phase spaces. The measurements are corrected for detector effects, presented as particle-level distributions and are compared to the predictions of different Monte Carlo event generators. New sets of recommended performance figures along with the related systematic uncertainties were also derived for several aspects of the ATLAS tracking, such as track reconstruction efficiency, fake rate and impact parameter resolution. These recommendations provide information on appropriate working points, i.e. track selection criteria with wellunderstood performance. They apply to physics analyses using Inner Detector tracks in Run 2 data and are important inputs for other objects based on tracks, such as jets. A simulation-based method which uses the tracking recommendations to calibrate light-jets mis-tagged as b-jets it is also presented in the context of the measurement of the crosssection of the W-boson produced in association with b-jets at 13 TeV, together with an overview of the inclusiveW-boson cross-section analysis.Item Charged-particle distributions and material measurements in ps = 13 TeV pp collisions with the ATLAS Inner Detector(2017-07-14) Cairo, Valentina Maria Martina; Pantano, Pietro; Dell'Acqua, Andrea; Schioppa, MarcoThe Run 2 of the Large Hadron Collider, which began in Spring 2015, offers new challenges to the Experiments with its unprecedented energy scale and high luminosity regime. To cope with the new experimental conditions, the ATLAS Experiment was upgraded during the first long shutdown of the collider, in the period 2013-2014. The most relevant change which occurred in the ATLAS Inner Detector was the installation of a fourth pixel layer, the Insertable B-Layer, at a radius of 33 mm together with a new thinner beam pipe. The Pixel Services, located between the Pixel and SCT detectors, were also modified. Owing to the radically modified ID layout, many aspects of the track reconstruction programs had to be re-optimized. In this thesis, the improvements to the tracking algorithms and the studies of the material distribution in the Inner Detector are described in detail, together with the improvements introduced in the geometry model description in simulation as well as the re-evaluation and the reduction of the systematic uncertainty on the estimate of the track reconstruction efficiency. The results of these studies were applied to the measurement of Charged-Particle Multiplicity in proton–proton collisions at a centre-of-mass energy of 13 TeV. The chargedparticle multiplicity, its dependence on transverse momentum and pseudorapidity and the dependence of the mean transverse momentum on the charged-particle multiplicity are presented for various fiducial phase spaces. The measurements are corrected for detector effects, presented as particle-level distributions and are compared to the predictions of different Monte Carlo event generators. New sets of recommended performance figures along with the related systematic uncertainties were also derived for several aspects of the ATLAS tracking, such as track reconstruction efficiency, fake rate and impact parameter resolution. These recommendations provide information on appropriate working points, i.e. track selection criteria with wellunderstood performance. They apply to physics analyses using Inner Detector tracks in Run 2 data and are important inputs for other objects based on tracks, such as jets. A simulation-based method which uses the tracking recommendations to calibrate light-jets mis-tagged as b-jets it is also presented in the context of the measurement of the crosssection of the W-boson produced in association with b-jets at 13 TeV, together with an overview of the inclusiveW-boson cross-section analysis.Item Charged-particle distributions and material measurements in ps = 13 TeV pp collisions with the ATLAS Inner Detector(2017-07-14) Cairo, Valentina Maria Martina; Pantano, Pietro; Schioppa, Marco; Dell'Acqua, AndreaThe Run 2 of the Large Hadron Collider, which began in Spring 2015, offers new challenges to the Experiments with its unprecedented energy scale and high luminosity regime. To cope with the new experimental conditions, the ATLAS Experiment was upgraded during the first long shutdown of the collider, in the period 2013-2014. The most relevant change which occurred in the ATLAS Inner Detector was the installation of a fourth pixel layer, the Insertable B-Layer, at a radius of 33 mm together with a new thinner beam pipe. The Pixel Services, located between the Pixel and SCT detectors, were also modified. Owing to the radically modified ID layout, many aspects of the track reconstruction programs had to be re-optimized. In this thesis, the improvements to the tracking algorithms and the studies of the material distribution in the Inner Detector are described in detail, together with the improvements introduced in the geometry model description in simulation as well as the re-evaluation and the reduction of the systematic uncertainty on the estimate of the track reconstruction efficiency. The results of these studies were applied to the measurement of Charged-Particle Multiplicity in proton–proton collisions at a centre-of-mass energy of 13 TeV. The chargedparticle multiplicity, its dependence on transverse momentum and pseudorapidity and the dependence of the mean transverse momentum on the charged-particle multiplicity are presented for various fiducial phase spaces. The measurements are corrected for detector effects, presented as particle-level distributions and are compared to the predictions of different Monte Carlo event generators. New sets of recommended performance figures along with the related systematic uncertainties were also derived for several aspects of the ATLAS tracking, such as track reconstruction efficiency, fake rate and impact parameter resolution. These recommendations provide information on appropriate working points, i.e. track selection criteria with wellunderstood performance. They apply to physics analyses using Inner Detector tracks in Run 2 data and are important inputs for other objects based on tracks, such as jets. A simulation-based method which uses the tracking recommendations to calibrate light-jets mis-tagged as b-jets it is also presented in the context of the measurement of the crosssection of the W-boson produced in association with b-jets at 13 TeV, together with an overview of the inclusiveW-boson cross-section analysisItem <> comunicazione scientifica nell'arte tra realtà e realtà aumentata(2014-06-05) Rinaudo, Daniela; Pantano, PietroItem <> genesi del circuito di Chua: uso del computer animation per divulgare la teoria del caos(2014-01-31) Laria, Giuseppe; Pantano, PietroItem Experimental and theoretical study of polyhedral carbon Nano-Onions(2018-02-23) Basantes Valverde, Marlon Danilo; Pantano, Pietro; Caputi, Lorenzo; De Luca, GiorgioCarbon nano-onions (CNOs), in their spherical or polyhedral forms, represent an important class of nanomaterials due to their peculiar physical and electrochemical properties. Among the different methods of production, arc discharge between graphite electrodes sustained by deionized water is one of the most promising to obtain good quality CNOs. The arc discharge method is applied to optimize the production of CNOs, and the synthesized nanomaterials by TEM was studied. An innovative experimental arrangement is used to obtain CNOs dispersed in water together with other carbon nanomaterials, and a black hard cathodic deposit. A simple mechanical grinding of the deposit it allowed to obtain turbostratic polyhedral CNOs with different aspect ratios, which exhibited higher stability towards burning in air, compared to CNOs found in water. A mechanism for the formation of the CNOs contained in the deposit, different from the generally accepted mechanism responsible for the synthesis of CNOs dispersed in water, is hypothesized. These spherical or polyhedral multi-shell fullerenes are widely studied owing to their interesting electronic and mechanical proprieties; nevertheless, comparative studies on these nanoparticles remain scarce. Herein, some key electronic proprieties of single and double walled icosahedral fullerenes as function of their sizes were calculated in the frame of the Density Functional Theory. In particular, structures of icosahedral polyhedral fullerenes, previously validated, were used to get the gap between the Highest Occupied Molecular Orbital and the Lowest Unoccupied Molecular Orbital levels (H-L gap), electron affinity, first ionization potential, electronegativity as well as the Density of the electronic States. This work shows that the H-L gap of the single-wall fullerenes decreases as the nanoparticles size increases, whereas an opposite trend was obtained for the double walled fullerenes. Going from single to double wall nanoparticles; a systematic and marked decrease of the H-L gap was found although, this difference reduces increasing the size of the double walled up obtaining an inversion. The DOS structures of SW nanoparticles changes radically adding a second shell, and the extent of these changes depends on the sizes of the analyzed fullerenesItem Study of the electronic and structural properties of tin dioxide and armchair graphene nanoribbons(2016-02-02) Villamagua Conza, Luis Miguel; Pantano, Pietro; Carini, Manuela; Stashans, ArvidsThis dissertation is focused on the study of the electrical and structural properties of two emerging materials, the tin dioxide (SnO2) and graphene, which have attracted the interest of the semiconductor-device community due to their extraordinary characteristics. The SnO2 has been studied by means of ab initio simulations (Vienna ab initio Simulation Package, VASP). Both n-type and p-type conductivities were investigated. The intrinsic n-type conductivity has been achieved through two schemes: the first one through the combination of oxygen deficiencies and interstitial atoms inside the SnO2 lattice, whereas in the second one, through the combination of interstitial and/or substitutional hydrogen atoms inside the SnO2 lattice. On the other hand, the p-type conductivity was achieved by codoping n-type SnO2 (from earlier configurations) with low concentrations of nitrogen and aluminum impurities. The performed theoretical studies, to a good extent, agree with the experimental results provided by our collaboration group at the National Central University, Jhong-Li (Taiwan). In prospective, these results confirmed that SnO2 is a promising candidate to replace indium in transparent conductive oxides (TCOs) used in photovoltaic, thin-film transistor, and transparent electronic applications. The theoretical study of graphene has been conducted by means of a tight-binding approach (Atomistic ToolKit simulation package, ATK): the electrical and structural properties of edge-defected armchair graphene nanoribbons (AGNRs) were studied. It was found that Stone-Wales defect (very common in carbon allotropes) placed at the edges of the AGNRs can spark an extra opening of the energy gap in graphene, in addition to that obtained through the quantum confinement of electrons. Moreover, an experimental study on the electrical properties of graphene was carried out at the Tyndall National Institute (Ireland) to understand the influence of multiple cleaning treatments on graphene field-effect transistor (GFET) devices. Debris from residual polymers that appeared during device fabrication was swept off the graphene surface without significantly degrading the electronic properties of the graphene flake. The results suggest that the unusual but extraordinary properties of these graphene allotropes can be considered as a very innovative booster for semiconductor devices, allowing the improvement of the scaling trend beyond that obtained with conventional materials.