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New evidence of functional interactions within the hand motor system
Get PDFHumans developed the ability to use their hands as tools to actively interact with the surrounding world. On a daily basis, without effort or a conscious will to act, we can manipulate dozens of objects placed in the environment to achieve different purposes. This, at first glance simple, ability relies on a network of cerebral areas computing a series of complex neural processes. The core cerebral regions involved in transforming visual inputs into hand actions have been identified within two distinct pareto-frontal networks, the dorsomedial and dorsolateral pathways. These pathways have been traditionally considered to process different types of information independently. The dual-route model of the hand motor system represents a milestone within the literature exploring the neural correlates of motor control. Nevertheless, following the recent improvement of the technical and analytical approaches adopted to investigate brain’s functioning, this initial description has been considered reductive. Nowadays, it is clear that the neural processes needed to produce a hand action require the integration of different information (e.g. spatial location of the object, spatial location of the arm, grip aperture, goal to pursue, etc.) that imply the exchange of information between anatomically distant, but functionally interconnected, cerebral areas.
In light of the most recent neuroscientific advance in the field of motor control, we investigated the specific role of the cerebral areas of the motor system and their functional interactions during the planning and execution of hand actions. In the present thesis, we adopted several methodologies (TMS, fMRI) and analysis approaches (univariate, MVPA, DCM), to explore the involvement of defined areas in specific motor tasks, their representational content and their connectivity profiles.
In the three neuroimaging studies here presented, we first considered the functional dynamics that occur within the hand network (Chapter 2). Secondly, we described a broader and integrated hand motor system including also the ventral stream, always considered as specialized in perceiving visual inputs (Chapter 3). Finally, we focused on the often neglected homologous regions within the right hemisphere (Chapter 4), providing a pan of the hand motor system in its entirety.
The first study (Chapter 2) adopted a combined TMS-fMRI approach, and focused on understanding the interactions between the dorsomedial and dorsolateral pathways of the hand motor system. We adopted a delayed-reach-and-grasp task, performed under different perceptual conditions (eyes opened or closed), and we perturbed the activity of SPOC in the dorsomedial pathway of the left hemisphere by means of rTMS. We used univariate and multivariate analysis to investigate the modifications occurring during the planning phase of the action within areas functionally connected with the region stimulated with TMS. We found that when the normal activity of SPOC is altered, changes in encoding grasping action information occur within the dorsolateral pathway. This study showed a causal interaction between the dorsomedial and dorsolateral pathway of the hand motor network, which are traditionally considered to be specialized and independent.
In the second study (Chapter 3), we adopted fMRI to explore the possible communication between dorsal and ventral stream, verifying the possible complementary and supportive role of the temporal cortex in motor control. To this aim, we adopted a delayed tool-pantomiming task known to recruit the ventral stream. Our delayed pantomiming task allowed us to consider the planning phase of the movement together with the execution of the pantomime. With multivariate analysis, we explored where in the dorsal and in the ventral streams different abstract goals of an action, i.e. independent from the tool identity, are represented in respect to more concrete aspects, related to the tool considered in the pantomime. In addition, we investigated the possible functional interactions between temporal and fronto-parietal regions, showing an exchange of information between the two pathways both with MVPA and connectivity analysis (DCM). Overall, these results point out a hand motor system that not only relies on the specialized-for-action dorsal network, but also on temporal lobe areas.
In the third study of the thesis (Chapter 4), we combined data from Chapter 3 with a complementary fMRI session. In the second session we changed instruction modality and effector used to perform the pantomime, while experimental design and the task requirement were unchanged. This approach allowed focusing on understanding: (i) changes in the encoding of concrete and abstract representation based on task requirements (i.e. different instruction modality and effector) and (ii) the possible encoding of tool pantomimes’ information also outside the classically-defined left-lateralized tool network, in homologous regions within the right hemisphere. Overall, we found task-dependent changes in the representational content of the considered areas both in the left and in the right hemisphere. These results provided novel insights into the neural correlates of tool pantomime, pointing towards the supportive role of the temporal cortices and of the right hemisphere when planning and pantomiming this type of action.
Overall, our studies contributed delineating a novel view on the organization of the hand motor system describing (i) the functional specialization of its different cerebral areas and (ii) the interactions occurring between these regions. Our research highlighted how the hand motor system has a functionally interconnected organization in which, to different degrees, various areas located in three main cerebral routes (ventral stream, dorsolateral and dorsomedial pathways) communicate to build a meaningful motor output
Study of Wear Mechanisms in Braking Systems with HVOF-Coated Discs
No full textThe European Union has undertaken several efforts to reduce the non-exhaust particulate matter emissions from road vehicles. One of the major sources of these emissions is the wear of brake pads and discs. The experimental work presented in this thesis has been performed within the European project called LOWBRASYS that aims at reducing the particulate matter emissions due to the wear of the components of braking systems. Different strategies have been identified for reaching this aim but the present work focuses on the investigation of the wear mechanisms at the disc-pad interface and on their role on the emission in the atmosphere and in the environment of wear debris. In order to achieve the reduction in the particulate matter emissions, the traditional gray cast iron discs have been coated with different cermet coatings deposited via high velocity oxygen fuel (HVOF) process. A further attempt for improving the wear resistance of the gray cast iron discs was performed by applying on them an industrial heat treatment. The cermet coatings have been widely employed in the field of the oil and gas industry for improving the wear resistance and the service life of valves and pipes but their use in the field of road-vehicles-braking-systems has never been explored so far. The present work focuses on the tribological characterization of HVOF coated and heat treated discs performed by means of laboratory-scale-pin-on-disc tribometers at both room and high temperatures (300°C). The sliding speed of 1.57 m/s and the nominal contact pressure of 1 MPa used for this characterization have been selected in order to replicate the actual contact conditions between brake pads and brake discs during an urban cycle braking action. Since the use of lab-scale experimental apparatuses, these tests have not been meant to reproduce real braking conditions for which specific dyno bench tests have been performed in further characterization tests. The pins used during the PoD characterization, made of three different commercially-available friction materials, had dimensions of 12 mm in height and 6 and 10 mm in diameter. The discs, 6 mm in thickness and 58.9 mm in diameter, were coated with a 70 µm thick layer of cermet materials. The heat treated discs had the same dimensions of the coated ones. The tested specimens have been machined from the real braking components, the pins have been extracted from the brake pads while the discs from the braking tracks of the rotors. Since the novelty of the application of the HVOF coatings in the field of braking systems, two preliminary studies of the surface parameters of the coated discs and of the running-in of the pin-disc system have been performed. The first one was conducted on WC-CoCr coated discs polished with different intensities in order to achieve four different average surface roughnesses: 5, 1, 0.1, 0.04 µm respectively. The results of the study highlighted that the wear of the friction material decreased by four order of magnitude by passing from an average surface roughness equal to 5 µm to 0.04 µm. The friction coefficient followed the opposite trend passing from 0.3 for the 5 µm rough coating to 0.7 for the 0.04 µm. The SEM observation of the wear tracks on the discs revealed a high material transfer from the pins in the case of the 5 µm rough coatings due to the abrasive interaction exerted by the hard coating asperities on the relatively soft friction material. The compactness of the material transferred onto the disc surface increased as the average surface roughness of the coating decreased leading to the formation of contact patches also on the coated disc surfaces. From the profilometric analysis of the worn disc their wear resulted negligible. The EDXS analysis of the secondary plateaus of pins detected an increasingly concentration of tungsten and cobalt with the decrease in the surface roughness of the coating meaning that, although the wear of the coating could not be detected from the profilometer, some minor transfer of material occurred during the sliding action. From all the considerations mentioned above the most promising surface roughness, in terms of frictional performances and industrial feasibility, was equal to 1 µm.
The second study aimed at the investigation of the running-in stage of the WC-CoCr and Cr3C2-NiCr coated discs in the as-sprayed (Ra ≈ 5 µm) and polished conditions (Ra ≈ 1 µm). From this former investigation the polishing procedure of the coated discs was found fundamental in order to reach the best frictional and wear performances; the spontaneous surface modifications occurring during pin-on-disc tests were not as efficient as the controlled polishing procedure in reducing the surface parameters of the coated discs and so in improving their performances.
On the basis of the results of the two former studies presented above, the tribological characterization at both room and high temperature (300°C) of the WC-CoCr, Cr3C2-NiCr, WC-Cr3C2-CoCr, WC-FeCrAlY coated discs and of the heat treated one was performed on specimens with an average surface roughness at around 1 µm. Three different friction material formulations were used in order to optimize their frictional and wear performances with the disc counterface. In all cases the EDXS analysis detected the presence of the coating elements, i.e. tungsten, cobalt and nickel, inside the secondary plateaus of the friction material. Depending on the abrasive content of the friction materials and on the testing temperature the amount of the transferred elements varied, i.e. a low amount of abrasives and a high testing temperature gave rise to a reduction in the elements transferred on the pin surfaces. The best tribological combination was the coupling between the friction material FMB, i.e. the one with the lowest amount of abrasives, and the WC-FeCrAlY coated disc.
The results attained with the pin-on-disc tribological characterization of the friction materials were validated during full-scale dyno bench tests. These tests were performed on the most promising materials and they had a twofold aim: as mentioned above they were used to validate the results of the tribometer tests and to collect the particulate matter emitted during braking. The analysis of the wear debris highlighted that, in the case of the friction material FM4 slid against the WC-CoCr coated disc, some cobalt was present. From the deeper analysis of the debris resulted that traces of tungsten and cobalt were found only in the coarser fraction of wear debris, collected on the PM1 filter. The coupled SEM+EDXS analysis of the finer particulate matter, with an average aerodynamic diameter varying from 0.25 to 0.054 µm, did not detected the presence of the coating elements. This was consistent with the observations of the PM1 wear debris that identified WC particles with dimensions comparable to that of the initial carbide particle size inside the coatings; the wear mechanism of the coatings seemed to be the carbide pullout from the metallic matrix without the further fragmentation of the particles due to sliding. Nevertheless, during one of the TEM observation of the particles with an average aerodynamic diameter of 0.094 µm the SAED analysis detected the presence of W2C. On the basis of this last observation and considering that the presence of cobalt inside the finest fraction of debris could not be completely disregarded since it could remain stuck on the W2C particles, the selected coating material for the application in braking systems was the WC-FeCrAlY. This conclusion was consistent with the frictional and wear data attained from the PoD tribological characterization that identified the FMB friction material and the WC-FeCrAlY coated discs as the best coupling in terms of frictional and wear behavior.
The study of the thermal behavior of the novel developed braking materials during a pin-on-disc room temperature test was performed by means of a finite element simulation based on the perfect contact approach. The heat flux applied as the thermal input of the model was calculated from the experimental data acquired during the tests. The calibration of the boundary conditions was performed by comparing the experimental curves of the temperatures acquired during the tests with the temperature curves calculated from the FE analysis. The results of the simulations showed that the temperature field during the pin-on-disc tests was influenced from both the friction coefficient and from the thermal properties of the coated discs, i.e. the lower thermal conductivity of the coatings gave rise to a higher average contact temperature with respect the uncoated cast iron discs. The results of FE analysis were then used to propose an analytical relationship that could be used for describing the raise in temperature during a pin-on-disc test without performing further thermal simulations
Learning from noisy data through robust feature selection, ensembles and simulation-based optimization
Get PDFThe presence of noise and uncertainty in real scenarios makes machine learning a challenging task. Acquisition errors or missing values can lead to models that do not generalize well on new data. Under-fitting and over-fitting can occur because of feature redundancy in high-dimensional problems as well as data scarcity. In these contexts the learning task can show difficulties in extracting relevant and stable information from noisy features or from a limited set of samples with high variance. In some extreme cases, the presence of only aggregated data instead of individual samples prevents the use of instance-based learning. In these contexts, parametric models can be learned through simulations to take into account the inherent stochastic nature of the processes involved. This dissertation includes contributions to different learning problems characterized by noise and uncertainty. In particular, we propose i) a novel approach for robust feature selection based on the neighborhood entropy, ii) an approach based on ensembles for robust salary prediction in the IT job market, and iii) a parametric simulation-based approach for dynamic pricing and what-if analyses in hotel revenue management when only aggregated data are available
Dynamic interaction between shear bands
Get PDFA shear band of finite length, formed inside a ductile material at a certain stage of a continued homogeneous strain, provides a dynamic perturbation to an incident wave field, which strongly influences the dynamics of the material and affects its path to failure. The investigation of this perturbation is presented for a ductile metal, with reference to the incremental mechanics of a material obeying the J_2-deformation theory of plasticity (a special form of prestressed, elastic, anisotropic, and incompressible solid). The treatment originates from the derivation of integral representations relating the incremental mechanical fields at every point of the medium to the incremental displacement jump across the shear band faces, generated by an impinging wave. The boundary integral equations (under the plane strain assumption) are numerically approached through a collocation technique, which takes account of the singularity at the shear band tips and permits the analysis of an incident wave impinging on a shear band.
It is shown that the presence of the shear band induces a resonance, visible in the incremental displacement field and in the stress intensity factor at the shear band tips, which promotes shear band growth. Moreover, the waves scattered by the shear band are shown to generate a fine texture of vibrations, parallel to the shear band line and propagating at a long distance from it, but leaving a sort of conical shadow zone, which emanates from the tips of the shear band.
Moreover, the approach is generalised to study the interaction of multiple shear bands showing that it may lead to resonance and corresponding growth of shear bands, but also to their annihilation. At the same time, multiple scattering may bring about focusing or, conversely, shielding from waves. Due to the difficulties inherent to the experimental analysis of time-harmonic dynamics of shear bands, the proposed mechanical model represents the only practical possibility of analyzing the fine micromechanisms governing material collapse and discloses the complex interplay between dynamics and shear band growth or arrest
Figure di un ossimoro. Interpretazioni della filosofia italiana dall'Unità ai nostri giorni
Get PDFNella tesi di dottorato dal titolo Figure di un ossimoro. Storie della filosofia italiana dall’Unità ai giorni nostri ci si propone di confrontare e analizzare tre differenti risposte alla stessa domanda: esiste una filosofia italiana? E se esiste, quali sono i caratteri che consentono di distinguerla dalle altre tradizioni nazionali?
Il problema che qui si pone è quello del carattere di per sé stesso ossimorico dell’espressione ‘filosofia nazionale’, in cui l’unione dei due termini appare contraddittorio alla luce della connessione istituita tra un soggetto – la filosofia – che ha o aspira ad avere carattere o validità universale e un aggettivo – nazionale – che sembra costringerlo indebitamente all’interno di una dimensione particolare.
Per questo motivo ci si concentra su tre momenti nei quali la discussione intorno a questo argomento è stata più accesa all’interno del dibattito filosofico nel nostro Paese.
Il primo capitolo della tesi è dedicato a Bertrando Spaventa, colui che Giovanni Gentile considera il primo ad aver scritto una «Storia della filosofia italiana». Principale esponente (insieme a Francesco De Sanctis) dell’hegelismo napoletano, Spaventa è autore negli anni immediatamente a cavallo dell’Unità d’Italia del volume La filosofia italiana nelle sue relazioni con la filosofia europea. Attraverso questo lavoro, lo schema storiografico della Lezioni hegeliane sulla storia della filosofia veniva ampliato, includendo al suo interno alcuni filosofi italiani contemporanei (principalmente Galluppi, Rosmini e Gioberti). Seguendo dettagliatamente il percorso che ha condotto Spaventa alla composizione dell’opera, questa tesi mira a smentire le accuse di ‘nazionalismo’ che sono state mosse al suo autore nel corso degli ultimi due secoli, fino ad oggi. Smarcando la Teoria della Circolazione del pensiero italiano sia dalle interpretazioni gentiliane che da quelle marxiste, si cerca infatti di mostrare come essa in realtà, oltre a costituire dichiaratamente e consapevolmente una risposta alle posizioni giobertiane (e, più in generale, neo-guelfe), rappresenti il primo vero tentativo di superare la retorica risorgimentale sul tema “filosofia italiana”. La principale preoccupazione di Spaventa si dimostra quella di smentire la posizione secondo cui la filosofia italiana, per mantenersi autentica, avrebbe dovuto al tempo stesso dimostrarsi autarchica rispetto alle elaborazioni filosofiche straniere colpevoli di comprometterne il messaggio. In questo modo si mostra la circostanzialità di un’opera come La filosofia italiana nelle sue relazioni con la filosofia europea, mettendo al tempo stesso in evidenza come essa sia il frutto di una specifica interpretazione della filosofia hegeliana circa il rapporto tra storia e filosofia, che determina una presa di posizione a proposito del ruolo ‘rivoluzionario’ della filosofia nel processo di costituzione dell’‘epoca’.
Il secondo capitolo è dedicato a Eugenio Garin, autore a sua volta di una famosa e fortunata “Storia della filosofia italiana”. Attraverso il confronto tra la prima edizione del ’47 e la seconda edizione del ’66, si mostra il progressivo abbandono da parte di Garin dei presupposti teorici che giustificavano la composizione di una Storia della filosofia italiana intesa á lá longue durée. In particolare, si collega questo riposizionamento storiografico di Garin alla riflessione metodologica condotta nel corso degli anni ’50. Attraverso il recupero di materiale inedito, vengono ricostruite le vicende del dibattito sul rapporto tra filosofia e storia della filosofia nell’Italia degli anni ’50, contribuendo a chiarire la posizione di Garin al suo interno e la scelta da parte dello storico di frammentare la narrazione storiografica in una costellazione di momenti determinati.
Nel terzo capitolo viene preso in considerazione il dibattito contemporaneo sull’Italian Theory. Attraverso una panoramica sulle posizioni più diffuse, si mettono in evidenza i vari significati che l’espressione ha assunto fuori dall’Italia (dov’è stata coniata) e nel nostro Paese. In particolare la ricerca si concentra sulla declinazione del tema offerta da Roberto Esposito, il quale, attraverso un l’uso della geofilosofia di Deleuze e Guattari, si è recentemente impegnato nella ricostruzione della genealogia dell’Italian Thought. Il rapporto dialettico tra le categorie geofilosofiche di ‘terra’ e ‘territorio’ è utilizzato da Esposito per giustificare una narrazione della storia della filosofia italiana che superi le difficoltà implicite nell’utilizzo di un’aggettivazione di tipo nazionale. Attraverso un confronto con le posizioni di Spaventa e Garin, si cerca qui di mettere in evidenza come l’utilizzo dell’aggettivo ‘Italian’, crei alcuni fraintendimenti dal punto di vista storiografico.
Questi tre autori, con modalità e argomentazioni diverse (che la tesi ricostruisce nel dettaglio), hanno risposto tutti affermativamente rispetto alla possibilità di distinguere una ‘filosofia italiana’ e tutti e tre hanno riconosciuto nel Rinascimento il momento genetico della ‘differenza italiana’. Per questo motivo, il quarto capitolo della tesi è dedicato alla ricostruzione delle immagini del Rinascimento che vengono presentate nei loro lavori e che si collegano alla particolare declinazione del tema ‘filosofia italiana’ offerta da ciascuno di loro, costituendo, in fondo, una sorta di ‘banco di prova’ delle loro posizioni. Bertrando Spaventa, in controtendenza rispetto alla storiografia italiana dell’epoca, propone un’immagine positiva del Rinascimento italiano, quale momento fondante della filosofia moderna. Attraverso il recupero del Rinascimento e il suo collegamento con la filosofia europea da Descartes a Hegel, Spaventa sfida apertamente la storiografia europea (da Brucker a Hegel a Tennemann), secondo la quale la mancata Riforma, avrebbe impedito all’Italia l’ingresso nella modernità filosofica. Eugenio Garin (di cui si prendono in considerazione solamente i lavori degli anni ’50, composti cioè a ridosso della Storia della filosofia Italiana), in accordo con quanto teorizzerà in La filosofia come sapere storico, àncora la sua ricostruzione della filosofia italiana dell’Umanesimo e del Rinascimento alla peculiare situazione storico-politica della Penisola e ne rintraccia la caratteristica principale in una certa propensione ad abbandonare ‘le grandi cattedrali di idee’ a favore di una ‘filosofia terrena’ che assume i tratti di una vera e propria ‘filosofia civile’. Spaventa, quindi, aveva cercato di mostrare le possibili connessioni che intercorrevano tra il nostro Rinascimento e la modernità europea conquistata attraverso la Riforma. Anche gli studi di Garin, una volta abbandonate le grandi narrazioni, tendevano progressivamente a concentrarsi sulla ricostruzione delle relazioni dei cenacoli culturali della penisola con il pensiero europeo. Se entrambi questi autori, quindi, avevano contribuito – in maniera ben diversa – ad accantonare quel “complesso di inferiorità” che da tempo accompagnava (e spesso ancora accompagna) la filosofia italiana, reinserendola all’interno di un percorso condiviso, nella tesi si mette in evidenza che, al contrario, l’Italian Thought, ne rintraccia la peculiarità nel suo essersi mantenuta ‘autonoma’ sin dal principio. In particolare, Roberto Esposito fa dell’esclusione della filosofia italiana dai percorsi seguiti dalla filosofia moderna il suo tratto distintivo, nonché il principale fattore che ne determinerebbe la capacità di sopravvivere al crollo dei paradigmi della modernità filosofica. In questo modo, quel il rapporto rispetto a quel ‘complesso di inferiorità’ viene rovesciato e si trasforma, se non in una pretesa di superiorità, almeno in una possibilità di vantaggio per la filosofia italiana. Un vantaggio che, tuttavia, deriva paradossalmente dal suo essere una filosofia costitutivamente amoderna in una ‘condizione postmoderna’
A Spatial Decision Support System for thermal energy planning at the regional scale
Get PDFThe focus of the Ph.D. dissertation is on the thermal part of the energy planning issue since the space conditioning (heating and cooling – H&C) of buildings represents about 75% of the energy consumed by European residential buildings and only 16% of the heating and cooling consumption is covered by renewable energy sources (RES). At the same time, the increased complexity of the spatial planning process when energy issues are involved has made clear the need for new “energy-aware” tools and methods used in this field.
The proposed methodology is GIS (Geographical Information System)-based and performed at regional scale given that the movement of energy planning activities from national to regional and local scale allows a much more detailed analysis of both the energy demand and supply, balancing them more effectively. The integration of the spatial dimension within energy analyses can also provide the decision-makers with a spatially-explicit approach towards the energy transition and the development of sustainable energy plans and strategies. The general aim of the Ph.D. thesis is to develop a Spatial Decision Support System (SDSS) allowing the decision-makers to take into account (during the planning process) both the improvement of the energy production from RES and the energy renovation of the existing building stock. The SDSS aims also to connect the energy planning (supply side) with spatial planning (demand side) by seeking synergies between the two fields. This connection is made taking advantage of the framework of the Strategic Environmental Assessment (SEA).
The Ph.D. thesis is partially developed within a European co-financed project included in the Interreg Alpine Space programme. The GRETA project was designed to foster the use of shallow geothermal energy (SGE) in energy plans and strategies along the Alps. SGE is a low-carbon source for H&C of buildings, which exploits the heat stored within the ground, a local source widely available and less dependent from changes in time compared to other RES. Despite this, its exploitation is not yet diffused and its growth is limited mainly by factors such as scarce knowledge, complicated and fragmented legislation, and high installation costs. Considering all these issues, the research questions that shaped the Ph.D. activities are:
➢ How to estimate the thermal energy demand of the residential building stock at the regional scale, as a starting point for developing sustainable energy strategies aimed at the reduction of the thermal energy consumption in the existing buildings.
➢ How to integrate this appraisal in the energy planning of a region in order to elaborate different scenarios for the energy balance between thermal demand and supply, fostering the use of shallow geothermal energy (SGE) that is a renewable source still not well-known and not exploited.
➢ How to encourage the connection between energy planning and spatial planning towards the common goal of sustainable energy transition, helping to fill the gap between the development of plans and strategies and their implementation, thanks to the Strategic Environmental Assessment (SEA) framework.
The proposed methodology has been applied in a case study, i.e. Valle d’Aosta, an Italian alpine region. Almost all the data processing is performed with open-source software (GRASS GIS, QGIS, Python, and R) and applying a spatially-explicit approach, for pushing the integration of the spatial dimension in the energy analysis. The spatial units of analysis are the single building and the census tract. The single building has been chosen as the smallest unit available for ensuring a better characterization of the thermal energy demand and of the potential energy production from SGE. Moreover, the scenario analysis for the energy renovation of buildings is better performed at the building level; so, it is particularly suitable for developing an SDSS. Nevertheless, some data processing is done at the census tract level, using aggregated and statistical information to estimate the required values at the building level. The reason for this twofold scale of analysis is that the data availability often changes depending on time, space and data provider. For instance, for the case study area only little data was available at the building level for the whole region. Therefore, the methodology integrates data from different sources to fill this knowledge gap.
The methodology applied in the case study is divided into two parts:
1) The first one concerns the data collection and processing for the spatial estimation of the space heating demand of the existing building stock. At the end of it, the technical and economic suitability of SGE (performed within the GRETA project) for covering the energy demand of buildings and replacing some fossil fuels is evaluated.
2) The second one is carried out in the framework of SEA, by defining common objectives and developing scenarios for the integration of SGE in the energy planning process, as the short-term objective, and the coordination of energy and spatial planning goals, as the long-term objective. In the Ph.D. thesis, SEA is intended as a conceptual framework for integrating energy and spatial planning, rather than as an evaluation tool.
The main outputs of the Ph.D. thesis are: (i) the spatial evaluation of the space heating demand of each residential building of the case study, without using the “archetypes approach”; (ii) the development of a method for the integration of data from different sources and for its estimation if missing at the building level; (iii) the use of SEA as a framework for connecting energy planning and spatial planning fields, to support strategic decision-making processes. Even though the Ph.D. case study is a typical alpine region, (iv) the developed methodology can be applied at different scales and not only on alpine regions but potentially in every kind of context. Since it strongly depends on the availability of data, the replicability of the methodology is quite high.
The main expected impacts of these outputs are: (1) SDSS allows to reach a trade-off between the number of input data and the level of detail often required by decision-makers; (2) SDSS can support the decision-makers allowing them to analyse from various viewpoints different energy scenarios and also to localise where is better to address the energy measures; (3) the results at the building level represent a starting point for defining and developing strategies for the energy transition of settlements at different scales; (4) SEA used as a strategic tool for integrating energy and spatial planning, by coordinating strategic objectives, and linking the thesis outputs to the energy decision-making process
Machine Learning Methods for Urban Computing
Get PDFMachine Learning Methods for Urban Computing World population is increasingly moving from rural areas to urban centers, making large cities densely populated. In urban areas, there is greater access to work, a wide variety of options for education and training, ease of transport and the abundance of attractive places within a few kilometers. Across huge cities, people tend to move more and have to do it faster than in the past. On the other hand, heavy traffic (e.g., traffic jams), overbuilding and changes in the urban lifestyle can cause several new problems such as noise, atmospheric pollution (i.e., smog) and severe traffic congestions. However, the rise of novel data sources and machine learning techniques can help to tackle such problems and improve the quality of life of citizens. Indeed, in a smart city environment, the huge amount of data generated daily can be captured by sensors, actuators, and mobile devices. It goes without saying that using such data opens the door to several applications, including forecasting of urban displacements, land use classification and event detection in an urban environment. Motived by these opportunities, Urban Computing (UC) leverages on heterogeneous data sources and applies machine learning techniques to tackle these big challenges that modern cities are facing. In this perspective, one of the core questions when designing UC systems is how to enable models to learn from different urban data sources and thus how to represent urban spaces. The mainstream approach is to represent input objects as feature vectors that encode several aspects of the urban environment such as the presence of people, density of urban activities, and mobility flows. However, this tedious approach of manually feature engineering can be extremely complex, time-consuming and domain-specific dependent. Additionally, it can become even more complex when aggregating multiple geographical data sources such as point-of- interests, administrative boundaries, and mobility data. A valid alternative to feature-based methods is using kernels, which are non-linear functions that map input examples into some high dimensional space allowing for learning more powerful discriminative decision functions. Given a representation of the input object, kernels map it into some high-dimensional space where implicitly a large number of features are generated, allowing for learning robust discriminative functions. In this way the effort for the feature engineering pro- cess can be greatly reduced. Machine Learning Methods for Urban Computing
Kernel methods have been widely applied in Natural Language Processing on tasks such as question answering, semantic role labeling and even for solving linguistic games. Taking inspiration from these successful cases, in this thesis we adapt kernel learning for solving novel tasks in UC. First, we focus on the problem of aggregating multiple urban data sources to provide datasets that fuse knowledge from a wide variety of data sources. Next, we focus on the problem of designing an input structure that is representative of urban space. In particular, we propose to model urban areas with tree structures that are fed to tree kernel functions for automatically generate expressive features. We propose several urban space representations that demonstrated to be very effecting in solving novel urban computing tasks such as land use classification and next location prediction in human mobility. Then, by applying a mining algorithm we enabled the interpretation of urban zones, providing help in the difficult problem of understanding the high-level urban characteristics of a city. In fact, our mined substructures provide help in identifying the different urban nature of cities. Finally, we explore the application of machine learning models to novel urban data sources by solving solve innovative tasks such as predicting the future presence of influenza-like symptoms looking at the people’s mobility behaviors
On-line sensing of the interlacing process
Get PDFThis thesis deals with the study of the yarn interlacing. The interlacing process is commonly employed by textile industries to impart cohesion points to a multi-filament yarn. Indeed, this work has been realized in the framework of a collaboration between the Department of Physics of the University of Trento (Italy) and Aquafil S.p.A., a company producing Nylon 6 yarn.
The interlacing of the filaments into periodic knots is caused by their interaction with a turbolent flow, but the full dynamics is not well characterized. Additionally, one problem that textile industries need to face is the irregularity of the process, still difficult to improve. A regular knots distance is required to ensure the homogeneous appearance of the final fabric.
Hence, it is interesting to understand which are the key parameters affecting and influencing interlacing, to improve its regularity. For this reason, the present work focuses on a deeper understanding of the process dynamics. Then, different on-line sensing techniques that measure the knots distance are investigated and compared. The evaluation of the process regularity during yarn production allows, as a further step, to change the machine parameters on-line, avoiding waste of time and material.
In Chapter 1 is given the background knowledge about the yarn production process, starting from the raw material. The attention will be focused on interlacing, with an overview of the state of the art literature on that topic.
In Chapter 2 the yarn-air interaction is investigated, with a high speed analysis of the yarn motion in an interlacer. A dynamics of interlacing is proposed, indicating the key role played by the turbolent pattern, observed by means of a tracer.
Chapter 3 studies the vibrations close to the interlacer, to monitor a possible flow modulation caused by the yarn-air interaction.
In Chapter 4 and Chapter 5 two sensing techniques have been approached, based on the use of a microphone and a photodiode. The issues related to those measurements have been investigated, for a final comparison of their performance in terms of capability of detecting the cohesion points distance on-line, on a running yarn
Contesting the European Union in times of crisis: an analysis of Facebook interactions
Get PDFThe Eurozone crisis and the migration crisis generated a set of decisions at the EU level that aims to jointly
mitigate the adverse consequences of economic and political turmoil. However, electoral successes by
Eurosceptics at both EU and national levels and shrinking public support for the EU, as evidenced by
Eurobarometer surveys, have shown that Euroscepticism has been surging in parallel with tighter cooperation
of member states in crisis-ridden policy areas. Consequently, EU institutions have embraced the connecting
potential of social media by implementing a series of online communication strategies aimed at selflegitimation and strengthening of public support for European integration.
This study addresses the nature of Euroscepticism as reflected in online discussions via conducting a qualitative
content analysis of Facebook debates unfolding on the pages of the European Parliament and the European
Commission during the peak moments of the Eurozone crisis and the migration crisis. Moreover, the study
identifies the public interpretations of different aspects of the two crises framed as existential for the process
of European integration. The rhetorical analysis of the Facebook posts reveals how EU institutions utilize social
media in order to respond to and normalise public discontent, whereas elite interviews triangulate the findings.
The analysis of EU-focused transnational discussions complements the existing studies drawing on public
opinion polls regarding public attitudes towards European integration, and re-conceptualises the common
explanations for public Euroscepticism, mainly based on utilitarian or cultural hypotheses. The findings
stemming from the rhetorical analysis and interviews demonstrate that EU crisis communication perpetuates
the ingrained neo-functionalist and elitist modes of interaction despite the novel online communication
setting
Surface Treatments to Protect Conventional and Rheo-High Pressure Die Cast Al-Si Alloys from Corrosion
Get PDFRheocasting process integrated with the high pressure die casting method (Rheo-HPDC) has established itself as a new promising technology to produce high-quality components. However, different types of microstructural segregation induced by the semi-solid process influence the properties of the final component. The semi-solid microstructural features and the new compositions require detailed corrosion studies and verification. The first part of this thesis deals with microstructural and corrosion studies of the conventional and Rheo-HPDC Al-Si alloys.
In this part, corrosion properties of two Al–Si alloys containing 2.5 and 4.5 wt % silicon cast by Rheo-HPDC method were examined in the diluted Harrison solution using polarization and electrochemical impedance spectroscopy (EIS) techniques on as-cast and ground surfaces.
The microstructural studies revealed that samples taken from different positions (with respect to the feeding gate) contain different fractions of solid and liquid parts of the initial slurry. It was shown that the Rheo-HPDC Al-Si alloys are prone to the localized form of corrosion inside the eutectic region at the interface of aluminum with silicon phase and intermetallic particles. Electrochemical behavior of as-cast, ground surface, and bulk material was shown to be different due to the presence of a segregated skin layer and the surface quality. Corrosion properties of the two Al-Si alloys cast by the conventional and Rheo-HPDC process were also evaluated and compared in 0.01, 0.05, 0.1 and 0.6 M NaCl solutions. The conventional HPDC and semi-solid alloys presented similar EIS responses. However, the semi-solid samples with a lower fraction of the eutectic phase showed slightly higher impedance values in the more diluted sodium chloride solutions. Corrosion morphological features, including localized corrosion, trenching and co-operative corrosion rings were comparable for both types of alloys. However, in the anodic polarization test, the semi-solid alloys presented a higher resistance to pitting corrosion.
To protect aluminum alloys from corrosion, chromium-based conversion coating has been successfully used for decades, due to its extensive protection. However, rising concerns and new restrictions on the environmental hazards of Cr (VI) compounds have led to intensive efforts to develop alternative coatings. The second and third parts of this thesis address the effort to investigate two alternatives in this field. Cerium-based conversion coatings were deposited on the conventional and Rheo-HPDC Al-Si alloys by immersion in cerium nitrate aqueous solutions. Different parameters were studied to optimize the conversion coating, and NaCl or H2O2 were also added to the solution to modify or accelerate the deposition process. The results revealed that applying cerium-based conversion coating on Al-Si alloys, is possible and a selective deposition is obtained due to the presence of iron-rich intermetallic particles inside the eutectic region. Under the accelerated conditions, the deposition mechanism includes dissolution of the aluminum matrix, selective dissolution of aluminum from the noble intermetallic particles, oxidation of iron from these particles, and the deposition of cerium hydroxide/oxide layer. The results revealed that the improvement in corrosion resistance in the presence of selectively deposited cerium-based conversion coating is more significant compared to the homogenous coating obtained from the conversion solution containing H2O2.
The aluminum alloy with a higher amount of silicon showed more active surface during the conversion process which reduces the required concentration of Ce(NO3)3 but also makes it difficult to work with more aggressive solutions.
In the third part of this thesis, the possible protective effect of polypyrrole coating on pure aluminum and Rheo-HPDC Al-Si alloys was investigated. Different electropolymerization solutions containing the Py monomer, SDS, DHBDS (Tiron), C6H8O7 and NaNO3 were used.
The presence of nitrate anions led to the passivation of the aluminum electrode (both pure and alloy) during the electropolymerization and to the deposition of a thicker/more conductive coating.
These facts resulted in longer and more efficient corrosion protection in NaCl solutions. This polypyrrole coating was able to keep the alloys’ surface potential noble for at least 168 hours. Which can be attributed to the anodic protection provided by the reduction of the polymer.
It was shown that the presence of silicon phase or intermetallic particles has a positive effect on the electropolymerization of polypyrrole film. Therefore, the coatings deposited on the alloys possess higher thicknesses compared to those deposited on the pure aluminum.
In the presence of chloride ions, all coatings suffered from the formation of blisters as a result of severe (localized) galvanic interaction of polypyrrole with aluminum. This may question the application of polypyrrole coating in concentrated NaCl solutions. However, it is shown that the protection efficiency can be improved by altering the solution chemistry which affects the polymer/metal interface and the conductivity and the barrier properties of the coating. Therefore, the application of polypyrrole in corrosion protection is not totally ruled out but needs specific considerations