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Navigazione di robot terrestri tramite analisi di traversabilità di ambienti outdoor
No full textThis thesis describes the research activity carried out on the navigation of unmanned ground vehicles in outdoor unstructured environments. These environments are very common in a wide variety of real-application scenarios, such as search and rescue for post-disaster response, monitoring of the environment and industrial facilities, precision farming, planetary exploration etc.. For this reason, robotics researchers have been investigating such kind of environments for decades. However, the problem of vehicle navigation in these scenarios is not fully solved. In fact, a general approach for ground vehicle motion planning, taking into account both the robot and the environment features, is still far to be defined. In the literature, this problem has been addressed through the so-called traversability analysis. It can be seen as an assessment of the difficulty for a specific ground vehicle, characterized by its own locomotion features, to cross a terrain area, which is in turn characterized by its own morphology and appearance.
The works reported in this thesis are related to the problem of geometry-based traversability analysis. It consists in deriving maps of traversing costs from three-dimensional models of the environment. These costmaps are extremely useful in challenging environments, as they are used in robot motion planning to avoid unsafe paths for the vehicle itself. Still in the context of 3D reconstructions, a solution for the remote drive of mobile robotic platforms has been developed. The aim has been to enhance the operator interface with helpful information, including traversing costs, via graphical elements presented in a mixed reality context. Finally, coverage path planning for unmanned aerial vehicles has been investigated as well. It is a specific kind of path planning related to three-dimensional photogrammetric reconstruction. In particular, an approach to manage a flock of aerial vehicles has been developed, in order to parallelize the coverage mission. The coverage task is the first step needed for the environment reconstruction. Eventually the traversability analysis can be performed on the obtained reconstruction.
Experimental and on-field trials have also been performed on a real mobile robotic platform, for the testing of the proposed approaches. The results achieved are reported and widely discussed
Methods for Sentiment Analysis and Social Media Popularity of Crowdsourced Visual Contents
No full textThis thesis collects all the research work done by the PhD candidate in the Joint Open Lab for Wireless Applications in multi-deVice Ecosystems (JOL WAVE Catania) of TIM Telecom Italia, which granted his doctoral fellowship.
The crowdsourcing paradigm opens new opportunities to understand various aspects of people's interactions, preferences and behaviors.
In this thesis we investigated methods aimed to infer people's reaction toward visual contents, under different headings.
We first focus on the task of understanding how people visit a place (e.g., a cultural heritage site) and infer what catch most their attention and interest, by means of the analysis of the shared photos taken by the users themselves.
Then, addressing the issues related to the noisy text associated to images, we defined a method for Image Popularity Prediction, considering an alternative source of text automatically extracted from the visual content. We first highlight the drawbacks of the text used in most of the state of the art methods, and then experimentally compared the two sources of text.
Starting from the analysis of the state of the art in image popularity prediction, we observed that a time-aware approach is needed, as the temporal normalization commonly employed in literature makes two contents published at different times incomparable. For this reason we introduced a new task, named Image Popularity Dynamics Prediction, which aims to predict the evolution of the engagement scores of a photo over a period of 30 days from its upload. To challenge the problem, we introduce a large scale dataset of 20K photos whose engagement scores have been tracked for 30 days. Moreover, we presented an approach that is able to perform the prediction at time zero.
Furthermore, we investigated methods for scene popularity estimation, from a set of videos taken by people attending a public event.
This involved the definition of methods for unsupervised video segmentation and scene clustering, able to work in both mobile and wearable domains.
The methods have been developed considering unconstrained scenarios without any prior on the input videos. In appendix, we also report some additional results and the pseudocode of the developed algorithms
Advanced Ecocomposites Materials
No full textThe thesis is divided into five chapters: the first four chapters cover the state of the art review on wood plastic composites, lignin and the recycling of bioplastics. The fifth chapter cover the experimental work of the thesis. In chapter fifth the materials and methods used are firstly presented followed by the discussion on the results obtained.
The research work performed during the PhD was focused on the development of novel eco-compatible thermoplastic composites. The experimental work was based on the use of two polymer matrices: polypropylene and poly(lactid acid). Polypropilene is not biodegradable but by the addition of a lignin based polymer the carbon biocontent was increased obtaining a formulation readily available and suitable for applications. The results presented on these blends outlined an increased thermal stability and mechanical resistance due to the addition of the lignin based system. This result is promising for the application of this blend in the automotive field. Many automotive parts, such as for example the under hood parts, require improved thermal performances that can be fulfilled by the proposed approach.
To overcome the problem of the use of petroleum based plastic the use of PLA was investigated in the research. PLA can be synthetized starting from sugar resulting in a ecofriendly matrix. PLA can be composted so it is a viable option to improve the ecocompability of polymers. However, PLA has an high cost of production which, since now, limited its acceptance in mass production. Therefore, to reduce PLA cost and, at the same time, improve the mechanical and thermal properties the addition of lignin was studied. The results obtained showed that, as for PP, lignin is a potentially good additive. However, the results showed some processing issues due to the thermal stability of PLA which was negatively affected by the reactive moiety of lignin.
The results obtained confirmed that combining natural fillers (i.e. lignin) with polymers synthetized by natural sources (i.e. PLA) promising blends can be obtained. However, processing should be optimized to minimize the degradation. To achieve such goal, a feasible process could be to chemical modify the lignin structure or the PLA matrix. Lignin is a multifunctional polymers thus, the approach could be oriented to link moiety which can reduce the interaction with the ester group of PLA.
In addition to the improvement of the thermal stability of PLA/Lignin blends future work will be oriented to the use of such blends as matrix for natural fiber composites. This further development will be pursued to obtain sytems suitable for structural applications
Least energy solutions for elliptic problems
No full textQuesta tesi di Dottorato riguarda lo studio dell'esistenza di soluzioni di minima energia e soluzioni nodali di minima energia per problemi ellittici non lineari in presenza di una nonlinearità con condizioni di crescita subcritica.
La tesi è divisa in tre capitoli. Nel primo capitolo vengono richiamati nozioni e risultati di base, che saranno necessari per dimostrare i nostri risultati principali. Infatti, in molti problemi di calcolo variazionali, non è sufficiente parlare di soluzioni classiche delle equazioni differenziali, ma è necessario introdurre la nozione di soluzione debole e lavorare nei cosiddetti spazi di Sobolev. Nel secondo capitolo, proviamo un risultato generale di esistenza di soluzioni di minima energia e soluzioni nodali di minima energia per un particolare problema problema di Dirichlet, caratterizzato da una funzione di Carathéodory. L'ultimo capitolo riguarda la generalizzazione di alcuni risultati precedenti ralativi a casi speciali di f. Infini, saranno proposti alcuni problemi aperti, riguardanti la restrizione alla varietà di Nehari del funzionale dell'energia associato al problema di Dirichlet, quando la non linearità è del tipo con and
TOF-based diagnostics system development and Geant4 simulation of the ELIMED transport and dosimetry beam line for high energy laser-driven ion beam applications @ ELI Beamlines
No full textThe acceleration processes based on the coherent interaction of high-power laser with matter is by now one of the most interesting topics in the field of particle acceleration, becoming a real alternative to conventional approaches. Some of the peculiarities of laser accelerated ion beams, if well controlled, are very promising for fundamental research as well as for multidisciplinary applications, including the medical field.
In this framework, a complete transport and dosimetry beam line, named ELIMED, has been realized at INFN-LNS and will be installed at ELI-Beamlines by the end of 2017.
It will be a section of the user-oriented ELIMAIA (ELI Multidisciplinary Applications of laser-Ion Acceleration) beam line at ELI-Beamlines, dedicated to the high-energy ion acceleration as well as high-intense X-rays generation and their possible multidisciplinary applications.
The present thesis describes the Monte Carlo Geant4-based application, simulating the complete ELIMED beam line, in terms of geometry as well as magnetic and electric fields.
Realistic top-to-bottom simulations have been performed to predict beam parameters and optimize dose distributions at the irradiation point in terms of homogeneity and dose delivered per shot in view of medical applications. In particular, the simulation performed clearly indicates the possibility to obtain a Spread Out Bragg Peak (SOBP) of clinical relevance with the selected proton beams. A specific on-line diagnostics system based on the Time Of Flight (TOF) technique coupled with diamond and/or silicon carbide detectors, has been developed and will be used for shot-to-shot energy distribution and flux
measurement. Considering the high-energy laser-driven ion beams that will be delivered at ELIMAIA, a new analysis procedure, optimized for high-energy laser-driven proton beams, to extract the energy distribution for a given in species from the TOF signal has been developed and validated. The experiments carried out in the multi-TW laser facilities, Rutherford Appleton Laboratory (RAL, UK), Ludwig Maximilians University Munchen (LMU, GE) and the Prague Asterix Laser System (PALS,CZ), will be described in details together with the results achieved using the TOF method for beam diagnostics. The results confirmed the reliability of the TOF technique and of the procedure developed for high-energy laser-driven ion beams, pointing out that TOF technique can be particularly
suitable for the on-line diagnosis of the high-energy ion beam characteristics, giving real time information useful to optimize transport as well as to investigate specific nuclear reactions occuring in the laser-target interaction
Effetti clinici e placentari dell'iperglicemia in gravidanza in donne con diabete mellito
No full textNelle donne diabetiche la placenta presenta delle alterazioni strutturali e funzionali potenzialmente correlabili a una disregolazione del sistema insulina/IGF che possono essere responsabili di un alterato trasporto di nutrienti al feto e di un aumentata crescita fetale. In queste donne la valutazione del sistema insulina/IGF placentare può fornire importanti informazioni sui meccanismi delle complicanze fetali/neonatali e materne e sulle patologie dell età evolutiva dei bambini nati da madre diabetica. Scopo dello studio è stato quello di valutare l effetto del compenso glicemico sulla placenta in termini di espressione di IR e IGF-1R e di valutare la fosforilazione recettoriale e la trasmissione del segnale intracellulare. Sono state studiate: 40 pazienti con gravidanza fisiologica, 20 pazienti con diabete gestazionale (GDM), 20 pazienti con diabete mellito tipo 1 (DMT1). Le pazienti con DMT1 hanno mostrato: una minore fosforilazione di AKT (0.6±0.1 UD) rispetto agli altri due gruppi (1.7±0.2 UD nel gruppo delle gravidanze fisiologiche; 1.9±0.6 UD nel gruppo GDM). Il dato permane anche se correggiamo i valori per la glicemia peri-parto. La deficitaria fosforilazione di AKT (e quindi una meno efficace attivazione della via metabolica), potrebbe essere implicata nella maggiore frequenza di macrosomia/LGA registrata nei neonati da madri con DMT1 (50%). Una simile tendenza è stata trovata quando, indipendentemente dalla diagnosi, le pazienti sono state divise in base alla presenza o meno della macrosomia: nelle placente delle donne con macrosomia la fosforilazione di AKT è risultata deficitaria rispetto alle placente delle donne senza macrosomia. Le pazienti con DMT1 hanno inoltre mostrato una maggiore fosforilazione di IGF-IR (3.6±0.6 UD) rispetto agli altri due gruppi (1.8±0.2 UD nel gruppo delle gravidanze fisiologiche; 2.9±0.8 UD nel gruppo GDM). Tale differenza significativa, però, scompare se correggiamo i valori per la glicemia peri-parto. Quindi tale maggiore fosforilazione potrebbe essere verosimilmente legata agli aumentati livelli di glicemia in acuto che si verificano nel periodo subito prima del parto. Ciò potrebbe significare che la fosforilazione di IGF-IR (rispetto a quella di IR) sia implicata nel determinismo di alcuni outcome neonatali sfavorevoli legati al periodo peri-parto (come ad esempio l ipoglicemia neonatale o la prematurità). Dall analisi di regressione lineare è emerso che l emoglobina glicata media del II e III trimestre correla positivamente con l espressione di AKT. Il peggiore compenso metabolico nelle fasi centrali della gravidanza potrebbe, quindi, condizionare la trasduzione del segnale intracellulare a valle del recettore insulinico. E inoltre emerso che il peso della placenta non correla con l espressione di IR, IGF-IR, ERK, AKT e con la loro fosforilazione nella placenta al momento del parto. Pertanto, potrebbero coesistere altri fattori in grado di influenzare la crescita della placenta. Tuttavia non si può escludere anche un ruolo di IR e IGF-IR dal momento che lo studio è stato effettuato a termine di gravidanza, mentre è possibile che tali recettori siano coinvolti in epoca gestazionale differente da quella finale.
In letteratura è riportato che IR, IGF-IR e i loro ligandi sono importanti per la crescita placentare e fetale, ma i dati nelle donne diabetiche sono scarsi. Questo è il primo studio in cui vengono messi in relazione gli esiti sfavorevoli della gravidanza con l espressione e la fosforilazione di fattori di crescita a livello placentare
Push-Pull copolymers in thin film for electronic application
No full textIn this work, push-pull copolymers have been synthesized by electrochemical and chemical methods in order to fabricate new devices on flexible substrates, for electronic applications in several areas as electrochromism, solar cells and sensors.
Electrochemical synthesis was employed to synthesize copolymers composed of acceptor (A) N,N -bis(2-octyldodecyl)-2,6-bis(5-(thioph-2-yl)thiophen-2-yl)naphthalene-1,4,5,8-bis(dicarboximide) (s-NDI2ODT4) and donor (D) ethylenedioxythiophene (EDOT) units on (indium tin oxide/polyethylene terephtalate) ITO/PET substrates, allowing for the fabrication of electrochromic devices, featuring an optical contrast of 29%. In the same way, it was possible to fabricate novel electrochromic devices by combining NDI2ODT4 with the novel system bis-thiophene fulleropyrrolidine (bis-Th2P-C60). Moreover, it was also possible to demonstrate that P(NDI2ODT4), P(bis-Th2P-C60), co(NDI2ODT4-bis-Th2P-C60) are good electron acceptor in planar heterojunction(PHJ)-based Organic Solar Cells (OSCs) with poly(3-hexylthiophene-2,5-diyl) (P3HT). Electrochromic devices and OSCs based on bis-Th2P-C60 combined with P(NDI2ODT4), do not show good results. This can be explained by the fact that bis-Th2P-C60 imposes a distortion of the main polymeric chain. In addition, the combination of fulleropyrrolidine (A) and thiophene (D) moieties in copolymers has shown to improve the morphology in thin film bulk heterojunctions (BHJs). In particular, the small percentages of a novel tetra-thiophene fulleropyrrolidine (Th4P-C60) copolymer acted as segregation modulators in BHJs based on P3HT mixed with Phenyl-C61-butyric acid methyl ester (PCBM) allowing to improve the state-of-the-art power conversion efficiency of plastic P3HT/PCBM OSCs up to 4.46 %.
Finally, preliminary results are shown on the application of Th4P-C60 based systems electrochemically co-deposited with hemin molecules for the recognition of H2O2 in plastic electrochemical sensors. This gives interesting perspectives for the application of properly designed D-A copolymers and/or co-deposited systems for the recognition of those drugs developing H2O2 during their metabolism
Properties and correlation of flares and coronal mass ejections and their possible relevance on the southern night sky background: a statistical study
No full textThis Thesis is devoted to a statistical study of solar phenomena (flares and coronal
mass ejections) and their possible effects on the Earth.
The Sun, our star, can be considered a huge laboratory where we can study the
interaction of a ionized gas with magnetic fields. In particular, the solar atmosphere
(the outer layers of the Sun, those which are accessible to observations) is characterized
by phenomena that due their existence to localized magnetic fields: sunspots,
faculae, filaments, active regions, bright points, coronal holes, etc. The occurrence
of these phenomena is variable, depending on the so-called activity cycle, characterized
by a period of 11 years.
Moreover, in some situations, the magnetic field that permeates the active regions,
from an initial potential field configuration (characterized by the minimum
energy content), can slowly store energy, changing its configuration to more complex
and more energetic ones. When the magnetic field configuration is not able
to maintain its equilibrium, the stored magnetic energy is abruptly released, giving
rise to phenomena that are generally termed as solar eruptions but that, depending
on their characteristics, are distinguished between flares, filament eruptions and
coronal mass ejections.
In the last decades, the possibilities offered by new computer capabilities, new
instruments and by satellite observations, have allowed us to understand many of
the characteristics of these eruptions, as well as their effects on the Earth magnetosphere
and ionosphere.
However, despite the progress in our comprehension of these phenomena, there
are still many aspects that need to be clarified: how and where is the energy stored,
what causes the trigger of the eruption, how the different phenomena are related to
each other and how they can affect our environment, to cite only a few.
In this scenario, the work carried out in this Thesis has been motivated by three
main questions:
-- Are there preferential locations on the Sun where the magnetic field is prone
to produce eruptive events ?
-- What kind of correlation exists between flares (mainly confined to the solar
atmosphere) and coronal mass ejections that, by definition, expel magnetized
clouds into the interplanetary space ?
-- Can the charged particles emitted during these events and arriving to the Earth
ionosphere have a role in the observed variations of the night-sky background?
The attempt to provide answers to the previous questions has been faced in this
Thesis from an observational / statistical point of view.
More precisely, the dataset that have been used in order to answer the first two
questions have been retrieved from public archives of flares and coronal mass ejections
relevant to the last two solar cycles (23 and 24), while in order to provide an
answer to the third question, also data acquired by the Pierre Auger Observatory
have been used.
The main results obtained in this Thesis can be summarized as follows:
-- The spatial and temporal distribution of the flares analyzed show persistent
domains of occurrence within well defined belts of longitude, with a behavior
similar to the one observed for other activity phenomena, like the sunspots.
-- There is a temporal correlation between flares and CMEs for the 60 % of the
events analyzed; the time interval (between 10-130 minutes) however depends
on the dataset used. Moreover, the majority of CMEs with highest velocities
show a clear temporal correlation with flares.
-- The variations in the night-sky background analyzed for the nights when a
major impact of charged particles associated to CMEs was expected, could not
be clearly correlated to these events
Procedure predittive e postdittive a supporto del remote sensign in archeologia. Casi studio dai comuni di Bronte e Maletto (CT)
No full textIl presente lavoro è finalizzato allo sviluppo di indagini archeologiche di tipo predittivo e postdittivo per un'area circoscritta del versante nord-occidentale dell'Etna. A tal fine, si è fatto ricorso alle possibilità offerte dal remote sensing e dalle analisi di immagini multilaterali space-born
Studio dei meccanismi patogenetici dell'insufficienza surrenalica nella cirrosi epatica
No full textAd oggi è ampiamente nota la prevalenza e la rilevanza clinica dell insufficienza surrenalica nel paziente cirrotico, rimangono tuttavia da chiarire i meccanismi patogenetici responsabili dell insorgenza della sindrome. Numerose teorie patogenetiche sono stata avanzate per spiegare l insorgenza dell insufficienza surrenalica nel paziente epatopatico tra le quali la carenza di substrati per la steroidogenesi, la disfunzione dell asse ipotalamo-ipofisi surrene, il danno strutturale della ghiandola e la resistenza tissutale ai glucocorticoidi. Abbiamo condotto un primo studio con lo scopo di indagare la carenza di substrati quale meccanismo patogenetico dell insufficienza surrenalica del cirrotico. Sono stati arruolati 81 pazienti con cirrosi e 30 sani di controllo, tutte le frazioni lipoproteiche sono state misurate e la funzionalità surrenalica (LDSST) è stata valutata in tutti i soggetti epatopatici. I pazienti cirrotici come noto, mostravano più bassi livelli di lipoproteine circolanti, tuttavia i livelli di HDL e Apo-AI risultavano parametri predittori di insufficienza surrenalica nei pazienti cirrotici stabili. In un secondo lavoro abbiamo invece testato l ipotesi del danno dell asse ipotalamo ipofisi surrene (HPA) come meccanismo patogenetico sottostante la disfunzione del surrene. 121 pazienti cirrotici sono stati consecutivamente arruolati e sottoposti dapprima al LDSST per lo studio della funzione del surrene, in caso di alterata risposta i pazienti sono stati sottoposti al LST, ossia ad una stimolazione prolungata con ACTH per valutare la risposta dell asse HPA. Il 55% dei pazienti con alterata risposta al LDSST mostravano una mancata produzione di cortisolo al LST suggerendo la presenza di un alterazione dell HPA in questi pazienti. Con lo scopo di testare la terza ipotesi patogenetica dell insufficienza surrenalica ossia la resistenza tissutale ai glucocorticoidi stiamo ad oggi conducendo due studi in parallelo su popolazione cirrotica stabile e ACLF