1731 research outputs found
Sort by
Indoor positioning using FM radio signals
No full textLocation based services are becoming an indispensable part of the life. Wide adoption of the Global Positioning System in mobile devices, combined with Wi-Fi and cellular networks, have practically solved the problem of outdoor localization and opened a new market. This, however, is the case only for outdoors. There are numerous areas of ubiquitous computing, which require the knowledge of user position indoors. Awareness of user's location is important in such areas as smart environments, assisted daily living, behaviour analysis studies.
Over the past years, a significant effort has been dedicated to development of indoor localization systems. The results vary in characteristics, performance, and cost. Despite the effort, the existing indoor positioning systems are still limited: they either require expensive infrastructure (UWB, ultrasound), have limited coverage (Wi-Fi, Bluetooth, RFID, DECT) or low accuracy (cellular networks). The cost of commercial systems is prohibitive for their wide adoption (Ubisense).
The main objective of this thesis was to determine the feasibility of indoor positioning using FM radio signals, generated either by local transmitters or by broadcasting FM stations. The performance of FM localization cannot be simply predicted from other technologies, such as Wi-Fi or GSM, due to significantly lower frequencies (around 100~MHz vs. units of GHz) leading to differences in signal propagation. Moreover, FM represents a popular and well-established technology, readily available in many mobile devices. At the infrastructure side, broadcasting FM stations provide almost ubiquitous coverage, while short-range FM transmitters are available license-free from conventional electronics markets.
The results indicate that indoor positioning using broadcasting FM stations outperforms in terms of accuracy both Wi-Fi and GSM indoor localization systems (for confidence levels up to 90% and in all cases, respectively). Due to the passive nature of the client devices, the system can be used in sensitive areas where local radio transmission, such as Wi-Fi or GSM, is prohibited for safety or security reasons. Finally, an FM receiver has significantly lower power consumption than a Wi-Fi module and provides 2.6 to 5.5 times longer battery life in localization mode
Active learning methods for classification and regression problems
No full textIn the pattern recognition community, one of the most critical problems in the design of supervised classification and regression systems is given by the quality and the quantity of the exploited training samples (ground-truth). This problem is particularly important in such applications in which the process of training sample collection is an expensive and time consuming task subject to different sources of errors. Active learning represents an interesting approach proposed in the literature to address the problem of ground-truth collection, in which training samples are selected in an iterative way in order to minimize the number of involved samples and the intervention of human users.
In this thesis, new methodologies of active learning for classification and regression problems are proposed and applied in three main application fields, which are the remote sensing, biomedical, and chemometrics fields. In particular, the proposed methodological contributions include: i) three strategies for the support vector machine (SVM) classification of electrocardiographic signals; ii) a strategy for SVM classification in the context of remote sensing images; iii) combination of spectral and spatial information in the context of active learning for remote sensing image classification; iv) exploitation of active learning to solve the problem of covariate shift, which may occur when a classifier trained on a portion of the image is applied to the rest of the image; moreover, several strategies for regression problems are proposed to estimate v) biophysical parameters from remote sensing data and vi) chemical concentrations from spectroscopic data; vii) a framework for assisting a human user in the design of a ground-truth for classifying a given optical remote sensing image.
Experiments conducted on simulated and real data sets are reported and discussed. They all suggest that, despite their complexity, ground-truth collection problems can be tackled satisfactory by the proposed approaches
Service life of organic coatings: strategies for improving aesthetic and protective durability
No full textIt is probably needless to mention that organic coatings are of paramount importance nowadays. Although the huge number of applications and their wide spread can suggest that organic coatings have now reached a level of maturity, they are still mysterious from a certain point of view. The behaviour of these systems is not completely understood yet, especially as regarding the relationships between the chemical formulation and the manufacturing/applications technologies on one side, and the final properties on the other side. In this scenario, durability is regarded the most crucial point and finding satisfying design solutions is not straightforward.
Automotive and architecture are perhaps two of the most challenging areas where the durability is claimed at overcoming hurdles and satisfying increasing expectations. The first part of this research handled durability issues in these two fields. Novel strategies for attaining high performance organic coatings were explored. In order to validate the proposed strategies, the research has been carried out in collaboration with industrial partners operating in these areas, thus making it possible to produce and test real organic coatings.
The second part of the investigation was aimed at exploring the corrosion protection capabilities of self-repairing organic coatings. The attention was specifically focused onto the preemptive healing polyurethane coatings and their barrier properties
Ri-formare il maschile: la strutturazione culturale contemporanea dell'identità maschile e la rappresentazione delle sue forme eccentriche in The Beast in the Jungle di Henry James, The Secret Sharer di Joseph Conrad e L'Immoraliste di André Gide
No full textIl presente lavoro è suddiviso in due macro-aree, ognuna delle quali sviluppa un'ulteriore segmentazione in capitoli. La prima macro-area tematizza la maschilità da un punto di vista eminentemente teorico e si coagula intorno a diverse unità concettuali problematiche quali la costruzione e la rappresentazione dell'identità maschile, del genere (gender) e della performance, cercando, così, di circoscrivere l'oggetto di studio della vasta disciplina nota al mondo accademico anglosassone col nome di Men's Studies, la quale sta godendo di una crescente visibilità.
Gli strumenti epistemologici interdisciplinari utilizzati per avvicinarsi al complesso mondo della maschilità provengono in larga parte dal pensiero femminista, le cui intuizioni teoriche hanno consentito di gettare le basi concettuali adatte a un'indagine sul maschile che permettesse di abbattere il tradizionale silenzio degli uomini sugli uomini. Il potere maschile, infatti, si sempre sottratto alle negoziazioni identitarie e si è appropriato indebitamente del discorso storiografico pubblico, imponendo il suo punto di vista come l'unica pratica epistemologica accettabile.
Grazie agli spunti di riflessione offerti dei principali esponenti della disciplina (Raewyn Connell, Harry Brod, Michael Kimmel solo per citarne alcuni) si cercherà di evidenziare le complessità legate alla discussione dell'identità maschile, alla costituzione e alle modalità performative della stessa. Nonostante la situazione di indubbio vantaggio socio-politico nella quale si trovano gli uomini - ma sarebbe più corretto specificare gli esponenti della cosiddetta "maschilità egemonica": bianca, occidentale, benestante, eterosessuale - diventare uomini sembra un processo faticoso che prevede un sempre maggiore scorporamento dall'elemento femminile con il quale ogni uomo si trova in una naturale simbiosi nel momento della nascita. Essere maschi si rivela in molti casi un percorso oppositivo, traumatico e doloroso, di allontanamento dalla femminilità: ciò che è proprio dell'identità maschile, in opposizione all'identità femminile, ha sede esattamente nella differenziazione e nella separazione dal materno. L'identità maschile sembra, più di quella femminile, un obiettivo da raggiungere, un traguardo che l'uomo ottiene dimostrando a se stesso e alla società di non essere un bebé, una donna, un omosessuale.
La forte componente normativa della maschilità egemonica produce l'esclusione degli uomini che non esibiscono dei tratti tradizionalmente "virili": su questa base, la seconda macro-area è legata all'analisi testuale di tre racconti, scritti a cavallo tra il diciannovesimo e il ventesimo secolo, i cui protagonisti esplorano dei percorsi eccentrici di maschilità e di desiderio maschile. La rappresentazione di un'identità che sembra allontanarsi dalle rigide e monolitiche pratiche di genere egemoniche dell'epoca presenta delle evidenti criticità.
The Beast in the Jungle (1903) di Henry James evidenzia la precarietà dei costrutti convenzionali della maschilità tradizionale, rappresentando l'angoscia esistenziale ed emotiva di un uomo incapace di amare la donna con la quale decide di condividere la propria vita e il peso oppressivo delle rigide e prescrittive strutturazioni identitarie di genere operate tacitamente dalle istituzioni sociali in cui il protagonista si trova a vivere e che gli impongono una continua dissimulazione. Marcher è un anti-eroe terrorizzato dall'esplorazione della propria sfera intima: attraverso il suo protagonista, James sperimenta una nuova forma di desiderio maschile che suggerisce interessanti orizzonti interpretativi della novella in un'ottica di genere. L'identità maschile di Marcher non percorre i consueti binari della maschilità egemonica eterosessuale: il posizionamento della sua soggettività maschile, così faticosamente ricercata nel corso della narrazione, si traduce nel racconto di una strutturazione identitaria complessa e sofferta, poiché disancorata da un orizzonte di desiderio condiviso dalla società dell'epoca. Oltre a infrangere un imperativo morale (non riuscire a provare passione per qualcuno che lo ama), Marcher si scontra anche con le aspettative sociali che lo vorrebbero impegnato con una donna in un legame eterosessuale stabile e codificato socio-culturalmente. Attraverso i modelli espressivi della preterizione e della perifrasi, che postulano il desiderio eccentrico come indicibile e innominabile, James riesce a strutturare e a rappresentare i dubbi, le sofferenze e le lacerazioni di un'identità maschile non ortodossa.
The Secret Sharer (1909), celebre racconto di Joseph Conrad, raffigura un microcosmo maschile nel quale il desiderio del capitano nei confronti del giovane fuggitivo che nasconde nella propria cabina porterà a un progressivo allontanamento dalla rigida giurisprudenza marittima, simbolo di un regime identitario patriarcale apparentemente inscalfibile. Ancora una volta, la poetica dell'indicibile permette di alludere a un'eccentricità di genere la cui piena espressione si sarebbe rivelata irrappresentabile. Attraverso la rappresentazione di uomini fragili, irrequieti, a volte codardi e capaci di azioni riprovevoli, Conrad mette in discussione le convenzioni narrative e contenutistiche che costituiscono tradizionalmente l'impianto strutturale della letteratura d'avventura per ragazzi, e, indirettamente, sembra voler rappresentare il conflitto tra la ripetizione di una maschilità vittoriana antiquata e oppressiva e l'articolazione sperimentale di nuove forme eccentriche del desiderio maschile. Conrad attacca un'ideologia di genere fortemente prescrittiva, ponendo sotto scrutinio la normatività di certi tratti ideali maschili. Vari elementi testuali contribuiscono a corroborare una lettura di The Secret Sharer come (anche) la storia di un'esplorazione momentanea di una forma d'identità maschile non conforme all'ortodossia vittoriana e la rappresentazione di piaceri fissati in un istante narrativo al di fuori delle coordinate sociali della spazialità e della temporalità. L'irruzione improvvisa del corpo nudo di Leggatt produrrà una tortuosa deviazione dai canonici percorsi formativi ed esperienziali di un ragazzo che si appresta a diventare uomo a bordo della propria nave, problematizzando quel "compito assegnato" dalla società alla sua esistenza, simboleggiato dal corpo (femminile) della nave che egli dovrà dimostrare di saper controllare e guidare. Sebbene non vi sia uno spazio pubblico e visibile per la maschilità eccentrica, Conrad sembra, tuttavia, permetterle una forma di sopravvivenza, pur anticipando, con una sensibilità che è stata definita proto-modernista, la crisi irreversibile in cui verserà la maschilità occidentale dalla prima guerra mondiale in poi e che trae le sue radici storico-culturali dalla rigida normatività vittoriana di genere, invocata dalle politiche imperialiste e rappresentata emblematicamente dai canoni, dalle convenzioni letterarie e dalle relazioni di genere della narrativa d'avventura per ragazzi, specchio di un mondo ormai in declino.
L'Immoraliste (1902), opera giovanile di Andrè Gide, descrive la riscoperta e la reinvenzione dell'antieroe in seguito a una lunga malattia. Michel, il protagonista, arriva a una definizione del proprio sé maschile attraverso il rifiuto della categoria egemonica di maschilità diffusa nella Francia fin de siècle. Gide illustra la possibilità di rappresentare delle forme non convenzionali di maschilità plurali: in seguito all'accettazione della propria identità più autentica, Michel è colpito da una malattia che lo porta quasi alla morte. Metaforicamente, a morire sarà la vecchia identità maschile di Michel, intossicato dai condizionamenti sociali che lo avevano intrappolato in una maschilità normativa e che erano fonte di enorme disagio esistenziale. Gide riesce a descrivere magistralmente le complesse traiettorie della psicologia del suo protagonista, immerso in un percorso faticoso di ricerca della propria identità maschile più autentica attraverso processi di auto-affermazione, di regressione, di sgretolamenti, di disagio esistenziale e di malattia. Attraverso la ricerca dei margini di possibilità e impossibilità di esplorare i confini simbolici tra la moralità, l'abiezione e il privilegio coloniale, Gide sembra voler delineare un profilo di identità maschile alternativo a quello egemonico e tradizionale, rappresentando una soggettività maschile diversa da quella ritenuta accettabile dalla classe borghese privilegiata nella Francia a cavallo tra il diciannovesimo e il ventesimo secolo.
L'obiettivo di questo lavoro consiste nel dimostrare come le categorie di genere così come ci sono state trasmesse soffrano di un'evidente precarietà; in particolare, l'identità maschile sembra essere un'entità ideale, monolitica, a volte opprimente, con una forte componente normativa, sempre più lontana dalla vita e dai corpi di molti uomini. I testi analizzati mostrano come già un secolo fa la costruzione egemonica del genere si rivelasse inadeguata e come gli autori si muovessero nella direzione di un ripensamento delle categorie della maschilità convenzionale e di una sperimentazione di nuove forme del sentire, verso ciò che si potrebbe definire, non senza una dovuta prudenza, una nuova scrittura maschile
Feature-Based Choice and Similarity Perception in Normal-Form Games: An Experimental Research
No full textIn my thesis, I investigate how strategic behavior forms in the mind of the subjects and how is it possible to influence or manipulate it, without proposing modifications of the utility function, but referring to possible logical and psychological processes.
I start from the assumption that agents are boundedly rational, and unable to process the whole information contained in a strategic situation. Moreover, they are also assumed to be unable to “rationally” process the
information they gathered, but rather look for intuitive solutions.
I claim that these “intuitive solutions” are largely influenced by some non-strategic features, and that manipulating them without altering the true strategic structure of the game would influence agents’ strategic behavior.
For this reason, I define this behavior as “feature-based choice”
Development of Free Energy Calculation Methods for the Study of Monosaccharides Conformation in Computer Simulations
No full textThis thesis is devoted to the study of the conformation of monosacchrides in six-membered ring form. The main goal is to develop and apply new computational tools to investigate conformational properties and to improve the description of carbohydrates in the framework of molecular dynamics simulations.
In the field of monosaccharides, modeling the system within the molecular dynamics framework presents troublesome aspects. The most important issue is that some force fields (e.g., the chosen gromos 45a4 parameter set) fail in reproducing the conformational preferences of the sugar constituents, with the appearance of unphysical conformations. This lack stems from the fact that the conformational behavior, dominated by few structures, generates a severe bottleneck: the non-ergodicity of the system by any practical means. This aspect explains the interest in free energy calculations, and methods exist, such as umbrella sampling or metadynamics, that allow to accelerate the sampling of different conformations by adding bias forces. In general, accelerated sampling methods are based on the choice of collective variables (CVs), which is of particular importance for the proper reconstruction of free energy landscapes. In the field of conformational analysis, suitable CVs have to be considered to describe non-planar, puckered conformations of cyclic structures.
One of the main goals of this work is the enhancement of the gromos 45a4 force field for carbohydrates, with respect to the ability to describe ring conformation (that is, puckering) of six-membered rings. To this end, the development of efficient computational tools for the investigation of the general puckering problem are presented. In particular, we indicate how to exploit the capabilities of the metadynamics algorithm applied to the investigation of puckered ring conformers, exploring also different parametrizations of puckered structures to assess their respective advantages as collective variables for metadynamics
On Neighbors, Groups and Application Invariants in Mobile Wireless Sensor Networks
No full textThe miniaturization and energy-efficient operation of wireless sensor networks (WSNs) provides unprecedented opportunities for monitoring mobile entities. The motivation for this thesis is drawn from real-world applications including monitoring wildlife, assisted living, and logistics. Nevertheless, mobility unveils a series of problems that do not arise in fixed scenarios. Through applications, we distill three of those, as follows.
Neighbor discovery, or knowing the identity of surrounding nodes, is the precondition for any communication between nodes. As compared to other existing solutions, we provide a framework that approaches the problem from the perspectives of latency (the time required to detect an amount of contacts), lifetime (the time nodes are expected to last) and probability (the fraction of contacts guaranteed to be detected within a given latency). By formalizing neighbor discovery as an optimization problem, we obtain a significant improvement w.r.t. the state-of-art. We offer a solver providing the optimal configuration and an implementation for popular WSN devices.
Group membership, or knowing the identity of the transitively connected nodes, can be either the direct answer to a requirement (e.g., caring for people that are not self-sufficient), or a building-block for higher-level abstractions. Earlier works on the same problem target either less constrained devices such as PDAs or laptops or, when targeting WSN devices, provide only post-deployment information on the group. Instead, we provide three protocols that cover the solution space. All our protocols empower each node with a
run-time global view of the group composition.
Finally, we focus on the behavior of the processes monitored by WSNs. We present a system that validates whether global invariants describing the safe behavior of a monitored system are satisfied. Although similar problems have been tackled before, the invariants we target are more complex and our system evaluates them in the network, at run-time. We focus on invariants that are expressed as first-order logic formulas over the state of multiple nodes. The requirement for monitoring invariants arises in both fixed and mobile
environments; we design and implement an efficient solution for each. Noteworthy is that the solution targeting mobility bestows each node with an eventually consistent view on the satisfaction of the monitored invariants; in this context, the group membership algorithms play the role of global failure detectors
Experimental study of ion-molecule reactions of aromatic hydrocarbons
No full textThis thesis presents experimental studies, based on guided ion beam mass spectrometric techniques and coupled to theoretical interpretations by quantum chemistry, on ionic mechanisms for the molecular growth of aromatic hydrocarbons with a particular relevance for understanding the formation of large molecules in ionized gases such as planetary iono-spheres, plasmas and combustion systems. The starting point of this dissertation is a study of the reactivity of naphthyl cation C10H7+ with benzene. Ion-molecule reactions leading to hydrocarbon growth via the formation of new C-C bond are studied with special reference to the association product C16H13+. Another experiment in this dissertation concerns the reactivity of the C12H9+ ion with benzene. The growth of hydrocarbon ions up to C18H15+ species via C–C bond forming reactions is observed. The adduct formation route is found to be exothermic and barrierless, while other products are found to have energy barriers. The last topic addressed in this thesis is the experimental investigation of the possible formation mechanisms of the ion C12H10O+, observed in benzene/air plasma corona discharges at atmospheric pressure
Hydrological simulations at basin scale using distributed model and remote sensing with a focus of soil moisture
Get PDFRemotely-sensed precipitation and soil moisture products are becoming increasingly important sources of information in earth science system. However, there are still high
degree of uncertainties inherited in remotely-sensed precipitation and soil moisture products, and limited studies have focused on evaluation of these products. In this study, GEOtop model (Rigon et al. 2006), which is physically-based distributed hydrological model, is used to assess the use of remotely-sensed precipitation and soil
moisture products for hydrological applications. The study area is Little Washita watershed (583 km2), Oklahoma, USA. To assess these products, the model has to be first calibrated and validated at different locations in the watershed using extensive ground-based measurements. The Southern Great Plains 1997 (SGP97) and SGP99 Hydrology Experiment are used for model calibration and validation, respectively. The model is reasonably calibrated and validated at watershed scale at different locations in
the watershed for: heat fluxes, soil temperature profiles, soil moisture profiles, and streamflows. Regarding soil moisture evolution, we studied the spatial variability of the near-surface soil moisture from GEOtop simulations and estimates from Electronically Scanned Thinned Array Radiometer (ESTAR). Results show that GEOtop simulations and ESTAR estimates show very different magnitude and spatial patterns of near-surface soil moisture. Spatial patterns derived from GEOtop simulations are in agreement with the previous findings obtained from the same study area using ground-based measurements of soil moisture and theoretical model simulations. We conclude that GEOtop simulation results are more accurate and that ESTAR estimates are not a reliable source of data for characterizing the spatial variability of near-surface soil
moisture. GEOtop simulations show that the spatial distribution of near-surface soil moisture is highly controlled by soil texture and river network. Furthermore, we investigated the effect of vegetation, surface roughness, and topography on ESTAR. Results show that there are insignificant effects of vegetation except for interception, surface roughness, and topography on ESTAR. In addition, we investigated the scaling properties of near-surface soil moisture. Results show that near-surface soil moisture has multiscaling behaviour. On the other hand, spatial soil moisture patterns are studied using geostatistical techniques: Ordinary kriging, external drift kriging and conditional Gaussian simulations (CGSs). Krigings show that soil moisture patterns in the watershed are highly controlled by gradient and cosine aspect. All CGSs clearly show soil moisture patterns. Spatial soil moisture patterns produced by CGSs are much better than the
patterns reproduced by kriging algorithms. Regarding remotely-sensed precipitation products, we have investigated the utility of these products for hydrological simulations during non-winter seasons. Results show that all remotely-sensed precipitation products (Climate Prediction Center’s morphing technique (CMORPH), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks - Cloud Classification System (PERSIANN-CCS)- and Next Generation Weather Radar (NEXRAD Stage III)) are fairly reproducing the streamflows, but CMORPH often overestimates streamflows. Thus it concluded that all the above mentioned remotely-sensed precipitation products have value for streamflow
simulations
Geometrical features induced in polymer structures by self-assembly and their exploitation for biomedical use
No full textIn material science, the possibility of creating chemical or physical patterns on various materials has opened a wide range of possibilities. Several techniques are available for patterning; among these, self assembled structures raised great interest. Changing the environmental humidity during solvent evaporation from a cast polymer solution, the condensation of water droplets is promoted, which self-assembled in a regular array; these drops form a template for the formation of an array of pores on the film, called Breath Figures. A similar mechanism seems to happen not only during film casting, but also during the formation of fibers in the electrospinning process.
This work is focused on the understanding of the mechanisms involved in pores formation due to the interaction of polymeric solution surface with humidity. The process parameters were controlled to tune the pores arrays features, according to the purpose they are used for. Moreover, the interface between the polymeric surface and the water droplets was exploited to promote the migration of hydrophilic chemical groups, obtaining the chemical functionalization of the inner surfaces of pores. In this way, a topographical and chemical pattern was obtained on the film surface. The formation of pores was studied on the surfaces of flat films and on electrospun fibers; both structures were developed for two main applications: drug release and interactions with cells. Porous films were demonstrated to release proteins in a controlled manner, depending on pores features and on chemical patterning. In particular, the release of protein with high molecular weight was developed. Films were demonstrated to influence cells adhesion depending on pores dimension and distribution.
Pores on the surface of fibers where demonstrated to influence the release of drugs from mats produced by coaxial electrospinning. Similarly to films, electrospun fibers were studied to understand their ability to influence cells behavior. The final aim is the production of patches for drug release and of scaffolds that combine the ability to support tissue growth and the release of therapeutic molecules