Reconstruction from image correspondences

A single picture provides a largely incomplete representation of the scene one is looking at. Usually it reproduces only a limited spatial portion of the scene according to the standpoint and the viewing angle, besides it contains only instantaneous information. Thus very little can be understood on the geometrical structure of the scene, the position and orientation of the observer with respect to it remaining also hard to guess. When multiple views, taken from different positions in space and time, observe the same scene, then a much deeper knowledge is potentially achievable. Understanding inter-views relations enables construction of a collective representation by fusing the information contained in every single image. Visual reconstruction methods confront with the formidable, and still unanswered, challenge of delivering a comprehensive representation of structure, motion and appearance of a scene from visual information. Multi-view visual reconstruction deals with the inference of relations among multiple views and the exploitation of revealed connections to attain the best possible representation. This thesis investigates novel methods and applications in the field of visual reconstruction from multiple views. Three main threads of research have been pursued: dense geometric reconstruction, camera pose reconstruction, sparse geometric reconstruction of deformable surfaces. Dense geometric reconstruction aims at delivering the appearance of a scene at every single point. The construction of a large panoramic image from a set of traditional pictures has been extensively studied in the context of image mosaicing techniques. An original algorithm for sequential registration suitable for real-time applications has been conceived. The integration of the algorithm into a visual surveillance system has lead to robust and efficient motion detection with Pan-Tilt-Zoom cameras. Moreover, an evaluation methodology for quantitatively assessing and comparing image mosaicing algorithms has been devised and made available to the community. Camera pose reconstruction deals with the recovery of the camera trajectory across an image sequence. A novel mosaic-based pose reconstruction algorithm has been conceived that exploit image-mosaics and traditional pose estimation algorithms to deliver more accurate estimates. An innovative markerless vision-based human-machine interface has also been proposed, so as to allow a user to interact with a gaming applications by moving a hand held consumer grade camera in unstructured environments. Finally, sparse geometric reconstruction refers to the computation of the coarse geometry of an object at few preset points. In this thesis, an innovative shape reconstruction algorithm for deformable objects has been designed. A cooperation with the Solar Impulse project allowed to deploy the algorithm in a very challenging real-world scenario, i.e. the accurate measurements of airplane wings deformations.

Methodologies for visual correspondence

Visual correspondence is a key computer vision task that aims at identifying projections of the same 3D point into images taken either from different viewpoints or at different time instances. This task has been the subject of intense research activities in the last years in scenarios such as object recognition, motion detection, stereo vision, pattern matching, image registration. The approaches proposed in literature typically aim at improving the state of the art by increasing the reliability, the accuracy or the computational efficiency of visual correspondence algorithms. The research work carried out during the Ph.D. course and presented in this dissertation deals with three specific visual correspondence problems: fast pattern matching, stereo correspondence and robust image matching. The dissertation presents original contributions to the theory of visual correspondence, as well as applications dealing with 3D reconstruction and multi-view video surveillance.

Sviluppo di un tomografo multi-energy per lo studio pre-clinico di nuove metodiche diagnostiche finalizzate al riconoscimento precoce della patologia tumorale

A new multi-energy CT for small animals is being developed at the Physics Department of the University of Bologna, Italy. The system makes use of a set of quasi-monochromatic X-ray beams, with energy tunable in a range from 26 KeV to 72 KeV. These beams are produced by Bragg diffraction on a Highly Oriented Pyrolytic Graphite crystal. With quasi-monochromatic sources it is possible to perform multi-energy investigation in a more effective way, as compared with conventional X-ray tubes. Multi-energy techniques allow extracting physical information from the materials, such as effective atomic number, mass-thickness, density, that can be used to distinguish and quantitatively characterize the irradiated tissues. The aim of the system is the investigation and the development of new pre-clinic methods for the early detection of the tumors in small animals. An innovative technique, the Triple-Energy Radiography with Contrast Medium (TER), has been successfully implemented on our system. TER consist in combining a set of three quasi-monochromatic images of an object, in order to obtain a corresponding set of three single-tissue images, which are the mass-thickness map of three reference materials. TER can be applied to the quantitative mass-thickness-map reconstruction of a contrast medium, because it is able to remove completely the signal due to other tissues (i.e. the structural background noise). The technique is very sensitive to the contrast medium and is insensitive to the superposition of different materials. The method is a good candidate to the early detection of the tumor angiogenesis in mice. In this work we describe the tomographic system, with a particular focus on the quasi-monochromatic source. Moreover the TER method is presented with some preliminary results about small animal imaging.

Evaluation of a multi variated analysis for the selection of t-tbar multijet events in the current CMS implemented environment at LHC

In the present study we are using multi variate analysis techniques to discriminate signal from background in the fully hadronic decay channel of ttbar events. We give a brief introduction to the role of the Top quark in the standard model and a general description of the CMS Experiment at LHC. We have used the CMS experiment computing and software infrastructure to generate and prepare the data samples used in this analysis. We tested the performance of three different classifiers applied to our data samples and used the selection obtained with the Multi Layer Perceptron classifier to give an estimation of the statistical and systematical uncertainty on the cross section measurement.

Cross-layer optimizations in multi-hop ad hoc networks

Unlike traditional wireless networks, characterized by the presence of last-mile, static and reliable infrastructures, Mobile ad Hoc Networks (MANETs) are dynamically formed by collections of mobile and static terminals that exchange data by enabling each other's communication. Supporting multi-hop communication in a MANET is a challenging research area because it requires cooperation between different protocol layers (MAC, routing, transport). In particular, MAC and routing protocols could be considered mutually cooperative protocol layers. When a route is established, the exposed and hidden terminal problems at MAC layer may decrease the end-to-end performance proportionally with the length of each route. Conversely, the contention at MAC layer may cause a routing protocol to respond by initiating new routes queries and routing table updates. Multi-hop communication may also benefit the presence of pseudo-centralized virtual infrastructures obtained by grouping nodes into clusters. Clustering structures may facilitate the spatial reuse of resources by increasing the system capacity: at the same time, the clustering hierarchy may be used to coordinate transmissions events inside the network and to support intra-cluster routing schemes. Again, MAC and clustering protocols could be considered mutually cooperative protocol layers: the clustering scheme could support MAC layer coordination among nodes, by shifting the distributed MAC paradigm towards a pseudo-centralized MAC paradigm. On the other hand, the system benefits of the clustering scheme could be emphasized by the pseudo-centralized MAC layer with the support for differentiated access priorities and controlled contention. In this thesis, we propose cross-layer solutions involving joint design of MAC, clustering and routing protocols in MANETs. As main contribution, we study and analyze the integration of MAC and clustering schemes to support multi-hop communication in large-scale ad hoc networks. A novel clustering protocol, named Availability Clustering (AC), is defined under general nodes' heterogeneity assumptions in terms of connectivity, available energy and relative mobility. On this basis, we design and analyze a distributed and adaptive MAC protocol, named Differentiated Distributed Coordination Function (DDCF), whose focus is to implement adaptive access differentiation based on the node roles, which have been assigned by the upper-layer's clustering scheme. We extensively simulate the proposed clustering scheme by showing its effectiveness in dominating the network dynamics, under some stressing mobility models and different mobility rates. Based on these results, we propose a possible application of the cross-layer MAC+Clustering scheme to support the fast propagation of alert messages in a vehicular environment. At the same time, we investigate the integration of MAC and routing protocols in large scale multi-hop ad-hoc networks. A novel multipath routing scheme is proposed, by extending the AOMDV protocol with a novel load-balancing approach to concurrently distribute the traffic among the multiple paths. We also study the composition effect of a IEEE 802.11-based enhanced MAC forwarding mechanism called Fast Forward (FF), used to reduce the effects of self-contention among frames at the MAC layer. The protocol framework is modelled and extensively simulated for a large set of metrics and scenarios. For both the schemes, the simulation results reveal the benefits of the cross-layer MAC+routing and MAC+clustering approaches over single-layer solutions.

Argumentation and artifacts for intelligent multi-agent systems

Reasoning under uncertainty is a human capacity that in software system is necessary and often hidden. Argumentation theory and logic make explicit non-monotonic information in order to enable automatic forms of reasoning under uncertainty. In human organization Distributed Cognition and Activity Theory explain how artifacts are fundamental in all cognitive process. Then, in this thesis we search to understand the use of cognitive artifacts in an new argumentation framework for an agent-based artificial society.

Multi-Country Event Study Methods

Which event study methods are best in non-U.S. multi-country samples? Nonparametric tests, especially the rank and generalized sign, are better specified and more powerful than common parametric tests, especially in multi-day windows. The generalized sign test is the best statistic but must be applied to buy-and-hold abnormal returns for correct specification. Market-adjusted and market-model methods with local market indexes, without conversion to a common currency, work well. The results are robust to limiting the samples to situations expected to be problematic for test specification or power. Applying the tests that perform best in simulation to merger announcements produces reasonable results.

EXAM-S: an Analysis tool for Multi-Domain Policy Sets

As distributed collaborative applications and architectures are adopting policy based management for tasks such as access control, network security and data privacy, the management and consolidation of a large number of policies is becoming a crucial component of such policy based systems. In large-scale distributed collaborative applications like web services, there is the need of analyzing policy interactions and integrating policies. In this thesis, we propose and implement EXAM-S, a comprehensive environment for policy analysis and management, which can be used to perform a variety of functions such as policy property analyses, policy similarity analysis, policy integration etc. As part of this environment, we have proposed and implemented new techniques for the analysis of policies that rely on a deep study of state of the art techniques. Moreover, we propose an approach for solving heterogeneity problems that usually arise when considering the analysis of policies belonging to different domains. Our work focuses on analysis of access control policies written in the dialect of XACML (Extensible Access Control Markup Language). We consider XACML policies because XACML is a rich language which can represent many policies of interest to real world applications and is gaining widespread adoption in the industry.

Ottimizzazione delle reti di distribuzione idrica tramite algoritmi genetici multi-obiettivo

Water distribution networks optimization is a challenging problem due to the dimension and the complexity of these systems. Since the last half of the twentieth century this field has been investigated by many authors. Recently, to overcome discrete nature of variables and non linearity of equations, the research has been focused on the development of heuristic algorithms. This algorithms do not require continuity and linearity of the problem functions because they are linked to an external hydraulic simulator that solve equations of mass continuity and of energy conservation of the network. In this work, a NSGA-II (Non-dominating Sorting Genetic Algorithm) has been used. This is a heuristic multi-objective genetic algorithm based on the analogy of evolution in nature. Starting from an initial random set of solutions, called population, it evolves them towards a front of solutions that minimize, separately and contemporaneously, all the objectives. This can be very useful in practical problems where multiple and discordant goals are common. Usually, one of the main drawback of these algorithms is related to time consuming: being a stochastic research, a lot of solutions must be analized before good ones are found. Results of this thesis about the classical optimal design problem shows that is possible to improve results modifying the mathematical definition of objective functions and the survival criterion, inserting good solutions created by a Cellular Automata and using rules created by classifier algorithm (C4.5). This part has been tested using the version of NSGA-II supplied by Centre for Water Systems (University of Exeter, UK) in MATLAB® environment. Even if orientating the research can constrain the algorithm with the risk of not finding the optimal set of solutions, it can greatly improve the results. Subsequently, thanks to CINECA help, a version of NSGA-II has been implemented in C language and parallelized: results about the global parallelization show the speed up, while results about the island parallelization show that communication among islands can improve the optimization. Finally, some tests about the optimization of pump scheduling have been carried out. In this case, good results are found for a small network, while the solutions of a big problem are affected by the lack of constraints on the number of pump switches. Possible future research is about the insertion of further constraints and the evolution guide. In the end, the optimization of water distribution systems is still far from a definitive solution, but the improvement in this field can be very useful in reducing the solutions cost of practical problems, where the high number of variables makes their management very difficult from human point of view.

New Synthetic Polyamines as Multi-Target-Directed Ligands for the Treatment of Alzheimer's Disease and Cancer: Design, Synthesis and Biological Evaluation

Alzheimer's disease (AD) and cancer represent two of the main causes of death worldwide. They are complex multifactorial diseases and several biochemical targets have been recognized to play a fundamental role in their development. Basing on their complex nature, a promising therapeutical approach could be represented by the so-called "Multi-Target-Directed Ligand" approach. This new strategy is based on the assumption that a single molecule could hit several targets responsible for the onset and/or progression of the pathology. In particular in AD, most currently prescribed drugs aim to increase the level of acetylcholine in the brain by inhibiting the enzyme acetylcholinesterase (AChE). However, clinical experience shows that AChE inhibition is a palliative treatment, and the simple modulation of a single target does not address AD aetiology. Research into newer and more potent anti-AD agents is thus focused on compounds whose properties go beyond AChE inhibition (such as inhibition of the enzyme β-secretase and inhibition of the aggregation of beta-amyloid). Therefore, the MTDL strategy seems a more appropriate approach for addressing the complexity of AD and may provide new drugs for tackling its multifactorial nature. In this thesis, it is described the design of new MTDLs able to tackle the multifactorial nature of AD. Such new MTDLs designed are less flexible analogues of Caproctamine, one of the first MTDL owing biological properties useful for the AD treatment. These new compounds are able to inhibit the enzymes AChE, beta-secretase and to inhibit both AChE-induced and self-induced beta-amyloid aggregation. In particular, the most potent compound of the series is able to inhibit AChE in subnanomolar range, to inhibit β-secretase in micromolar concentration and to inhibit both AChE-induced and self-induced beta-amyloid aggregation in micromolar concentration. Cancer, as AD, is a very complex pathology and many different therapeutical approaches are currently use for the treatment of such pathology. However, due to its multifactorial nature the MTDL approach could be, in principle, apply also to this pathology. Aim of this thesis has been the development of new molecules owing different structural motifs able to simultaneously interact with some of the multitude of targets responsible for the pathology. The designed compounds displayed cytotoxic activity in different cancer cell lines. In particular, the most potent compounds of the series have been further evaluated and they were able to bind DNA resulting 100-fold more potent than the reference compound Mitonafide. Furthermore, these compounds were able to trigger apoptosis through caspases activation and to inhibit PIN1 (preliminary result). This last protein is a very promising target because it is overexpressed in many human cancers, it functions as critical catalyst for multiple oncogenic pathways and in several cancer cell lines depletion of PIN1 determines arrest of mitosis followed by apoptosis induction. In conclusion, this study may represent a promising starting pint for the development of new MTDLs hopefully useful for cancer and AD treatment.

Tecnologie appropriate per la gestione delle georisorse nei paesi in via di sviluppo e nei paesi dell'America Latina. Creazione di una metodologia multi criteria per la valutazione dei progetti di sviluppo umano

Benessere delle popolazioni, gestione sostenibile delle risorse, povertà e degrado ambientale sono dei concetti fortemente connessi in un mondo in cui il 20% della popolazione mondiale consuma più del 75% delle risorse naturali. Sin dal 1992 al Summit della Terra a Rio de Janeiro si è affermato il forte legame tra tutela dell’ambiente e riduzione della povertà, ed è anche stata riconosciuta l’importanza di un ecosistema sano per condurre una vita dignitosa, specialmente nelle zone rurali povere dell’Africa, dell’Asia e dell’America Latina. La natura infatti, soprattutto per le popolazioni rurali, rappresenta un bene quotidiano e prezioso, una forma essenziale per la sussistenza ed una fonte primaria di reddito. Accanto a questa constatazione vi è anche la consapevolezza che negli ultimi decenni gli ecosistemi naturali si stanno degradando ad un ritmo impressionate, senza precedenti nella storia della specie umana: consumiamo le risorse più velocemente di quanto la Terra sia capace di rigenerarle e di “metabolizzare” i nostri scarti. Allo stesso modo aumenta la povertà: attualmente ci sono 1,2 miliardi di persone che vivono con meno di un dollaro al giorno, mentre circa metà della popolazione mondiale sopravvive con meno di due dollari al giorno (UN). La connessione tra povertà ed ambiente non dipende solamente dalla scarsità di risorse che rende più difficili le condizioni di vita, ma anche dalla gestione delle stesse risorse naturali. Infatti in molti paesi o luoghi dove le risorse non sono carenti la popolazione più povera non vi ha accesso per motivi politici, economici e sociali. Inoltre se si paragona l’impronta ecologica con una misura riconosciuta dello “sviluppo umano”, l’Indice dello Sviluppo Umano (HDI) delle Nazioni Unite (Cfr. Cap 2), il rapporto dimostra chiaramente che ciò che noi accettiamo generalmente come “alto sviluppo” è molto lontano dal concetto di sviluppo sostenibile accettato universalmente, in quanto i paesi cosiddetti “sviluppati” sono quelli con una maggior impronta ecologica. Se allora lo “sviluppo” mette sotto pressione gli ecosistemi, dal cui benessere dipende direttamente il benessere dell’uomo, allora vuol dire che il concetto di “sviluppo” deve essere rivisitato, perché ha come conseguenza non il benessere del pianeta e delle popolazioni, ma il degrado ambientale e l’accrescimento delle disuguaglianze sociali. Quindi da una parte vi è la “società occidentale”, che promuove l’avanzamento della tecnologia e dell’industrializzazione per la crescita economica, spremendo un ecosistema sempre più stanco ed esausto al fine di ottenere dei benefici solo per una ristretta fetta della popolazione mondiale che segue un modello di vita consumistico degradando l’ambiente e sommergendolo di rifiuti; dall’altra parte ci sono le famiglie di contadini rurali, i “moradores” delle favelas o delle periferie delle grandi metropoli del Sud del Mondo, i senza terra, gli immigrati delle baraccopoli, i “waste pickers” delle periferie di Bombay che sopravvivono raccattando rifiuti, i profughi di guerre fatte per il controllo delle risorse, gli sfollati ambientali, gli eco-rifugiati, che vivono sotto la soglia di povertà, senza accesso alle risorse primarie per la sopravvivenza. La gestione sostenibile dell’ambiente, il produrre reddito dalla valorizzazione diretta dell’ecosistema e l’accesso alle risorse naturali sono tra gli strumenti più efficaci per migliorare le condizioni di vita degli individui, strumenti che possono anche garantire la distribuzione della ricchezza costruendo una società più equa, in quanto le merci ed i servizi dell’ecosistema fungono da beni per le comunità. La corretta gestione dell’ambiente e delle risorse quindi è di estrema importanza per la lotta alla povertà ed in questo caso il ruolo e la responsabilità dei tecnici ambientali è cruciale. Il lavoro di ricerca qui presentato, partendo dall’analisi del problema della gestione delle risorse naturali e dal suo stretto legame con la povertà, rivisitando il concetto tradizionale di “sviluppo” secondo i nuovi filoni di pensiero, vuole suggerire soluzioni e tecnologie per la gestione sostenibile delle risorse naturali che abbiano come obiettivo il benessere delle popolazioni più povere e degli ecosistemi, proponendo inoltre un metodo valutativo per la scelta delle alternative, soluzioni o tecnologie più adeguate al contesto di intervento. Dopo l’analisi dello “stato del Pianeta” (Capitolo 1) e delle risorse, sia a livello globale che a livello regionale, il secondo Capitolo prende in esame il concetto di povertà, di Paese in Via di Sviluppo (PVS), il concetto di “sviluppo sostenibile” e i nuovi filoni di pensiero: dalla teoria della Decrescita, al concetto di Sviluppo Umano. Dalla presa di coscienza dei reali fabbisogni umani, dall’analisi dello stato dell’ambiente, della povertà e delle sue diverse facce nei vari paesi, e dalla presa di coscienza del fallimento dell’economia della crescita (oggi visibile più che mai) si può comprendere che la soluzione per sconfiggere la povertà, il degrado dell’ambiente, e raggiungere lo sviluppo umano, non è il consumismo, la produzione, e nemmeno il trasferimento della tecnologia e l’industrializzazione; ma il “piccolo e bello” (F. Schumacher, 1982), ovvero gli stili di vita semplici, la tutela degli ecosistemi, e a livello tecnologico le “tecnologie appropriate”. Ed è proprio alle Tecnologie Appropriate a cui sono dedicati i Capitoli successivi (Capitolo 4 e Capitolo 5). Queste sono tecnologie semplici, a basso impatto ambientale, a basso costo, facilmente gestibili dalle comunità, tecnologie che permettono alle popolazioni più povere di avere accesso alle risorse naturali. Sono le tecnologie che meglio permettono, grazie alle loro caratteristiche, la tutela dei beni comuni naturali, quindi delle risorse e dell’ambiente, favorendo ed incentivando la partecipazione delle comunità locali e valorizzando i saperi tradizionali, grazie al coinvolgimento di tutti gli attori, al basso costo, alla sostenibilità ambientale, contribuendo all’affermazione dei diritti umani e alla salvaguardia dell’ambiente. Le Tecnologie Appropriate prese in esame sono quelle relative all’approvvigionamento idrico e alla depurazione dell’acqua tra cui: - la raccolta della nebbia, - metodi semplici per la perforazione di pozzi, - pompe a pedali e pompe manuali per l’approvvigionamento idrico, - la raccolta dell’acqua piovana, - il recupero delle sorgenti, - semplici metodi per la depurazione dell’acqua al punto d’uso (filtro in ceramica, filtro a sabbia, filtro in tessuto, disinfezione e distillazione solare). Il quinto Capitolo espone invece le Tecnolocie Appropriate per la gestione dei rifiuti nei PVS, in cui sono descritte: - soluzioni per la raccolta dei rifiuti nei PVS, - soluzioni per lo smaltimento dei rifiuti nei PVS, - semplici tecnologie per il riciclaggio dei rifiuti solidi. Il sesto Capitolo tratta tematiche riguardanti la Cooperazione Internazionale, la Cooperazione Decentrata e i progetti di Sviluppo Umano. Per progetti di sviluppo si intende, nell’ambito della Cooperazione, quei progetti che hanno come obiettivi la lotta alla povertà e il miglioramento delle condizioni di vita delle comunità beneficiarie dei PVS coinvolte nel progetto. All’interno dei progetti di cooperazione e di sviluppo umano gli interventi di tipo ambientale giocano un ruolo importante, visto che, come già detto, la povertà e il benessere delle popolazioni dipende dal benessere degli ecosistemi in cui vivono: favorire la tutela dell’ambiente, garantire l’accesso all’acqua potabile, la corretta gestione dei rifiuti e dei reflui nonché l’approvvigionamento energetico pulito sono aspetti necessari per permettere ad ogni individuo, soprattutto se vive in condizioni di “sviluppo”, di condurre una vita sana e produttiva. È importante quindi, negli interventi di sviluppo umano di carattere tecnico ed ambientale, scegliere soluzioni decentrate che prevedano l’adozione di Tecnologie Appropriate per contribuire a valorizzare l’ambiente e a tutelare la salute della comunità. I Capitoli 7 ed 8 prendono in esame i metodi per la valutazione degli interventi di sviluppo umano. Un altro aspetto fondamentale che rientra nel ruolo dei tecnici infatti è l’utilizzo di un corretto metodo valutativo per la scelta dei progetti possibili che tenga presente tutti gli aspetti, ovvero gli impatti sociali, ambientali, economici e che si cali bene alle realtà svantaggiate come quelle prese in considerazione in questo lavoro; un metodo cioè che consenta una valutazione specifica per i progetti di sviluppo umano e che possa permettere l’individuazione del progetto/intervento tecnologico e ambientale più appropriato ad ogni contesto specifico. Dall’analisi dei vari strumenti valutativi si è scelto di sviluppare un modello per la valutazione degli interventi di carattere ambientale nei progetti di Cooperazione Decentrata basato sull’Analisi Multi Criteria e sulla Analisi Gerarchica. L’oggetto di questa ricerca è stato quindi lo sviluppo di una metodologia, che tramite il supporto matematico e metodologico dell’Analisi Multi Criteria, permetta di valutare l’appropriatezza, la sostenibilità degli interventi di Sviluppo Umano di carattere ambientale, sviluppati all’interno di progetti di Cooperazione Internazionale e di Cooperazione Decentrata attraverso l’utilizzo di Tecnologie Appropriate. Nel Capitolo 9 viene proposta la metodologia, il modello di calcolo e i criteri su cui si basa la valutazione. I successivi capitoli (Capitolo 10 e Capitolo 11) sono invece dedicati alla sperimentazione della metodologia ai diversi casi studio: - “Progetto ambientale sulla gestione dei rifiuti presso i campi Profughi Saharawi”, Algeria, - “Programa 1 milhão de Cisternas, P1MC” e - “Programa Uma Terra e Duas Águas, P1+2”, Semi Arido brasiliano.