Dipartimento di Ingegneria Informatica, Modellistica, Elettronica e Sistemistica - Tesi di Dottorato

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Questa collezione raccoglie le Tesi di Dottorato afferenti al Dipartimento di Ingegneria Informatica, Modellistica, Elettronica e Sistemistica dell'Università della Calabria.

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    Entity resolution: effective schema and data reconciliation.
    (2004) Folino, Francesco; Talia, Domenico; Saccà, Domenico; Manco, Giuseppe
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    Declarative Semantics for Consistency Maintenance
    (2006) Caroprese, Luciano; Zumpano, Ester; Talia, Domenico
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    Il Problema del VMI: un approccio risolutivo basato sul metodo di decomposizione
    (2008) Rende, Francesco; Musmanno, Roberto; Laganà, Demetrio; Grandinetti, Lucio
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    Modelling complex data mining applications in a formal framework
    (2008) Locane, Antonio; Saccà, Domenico; Manco, Giuseppe; Talia, Domenico
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    Schedulazione di agenti in un Call Center Multiskill
    (2008) Pisacane, Ornella; Grandinetti, Lucio; L'Ecuyer, Pierre; Musmanno, Roberto
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    Resource reservation protocol and predictive algorithms for QoS support in wireless environments
    (2008-01) Fazio, Peppino; Talia, Domenico; Marano, Salvatore
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    Advances in mining complex data: modeling and clustering
    (2009) Ponti,Giovanni; Greco,Sergio; Palopoli,Luigi
    In the last years, there has been a great production of data that come from di®erent application contexts. However, although technological progress pro- vides several facilities to digitally encode any type of event, it is important to de¯ne a suitable representation model which underlies the main character- istics of the data. This aspect is particularly relevant in ¯elds and contexts where data to be archived can not be represented in a ¯x structured scheme, or that can not be described by simple numerical values. We hereinafter refer to these data with the term complex data. Although it is important de¯ne ad-hoc representation models for complex data, it is also crucial to have analysis systems and data exploration tech- niques. Analysts and system users need new instruments that support them in the extraction of patterns and relations hidden in the data. The entire process that aims to extract useful information and knowledge starting from raw data takes the name of Knowledge Discovery in Databases (KDD). It starts from raw data and consists in a set of speci¯c phases that are able to transform and manage data to produce models and knowledge. There have been many knowledge extraction techniques for traditional structured data, but they are not suitable to handle complex data. Investigating and solving representation problems for complex data and de¯ning proper algorithms and techniques to extract models, patterns and new information from such data in an e®ective and e±cient way are the main challenges which this thesis aims to face. In particular, two main aspects related to complex data management have been investigated, that are the way in which complex data can be modeled (i.e., data modeling), and the way in which homogeneous groups within complex data can be identi¯ed (i.e., data clustering). The application contexts that have been objective of such studies are time series data, uncertain data, text data, and biomedical data. It is possible to illustrate research contributions of this thesis by dividing them into four main parts, each of which concerns with one speci¯c area and data type: vi Abstract Time Series | A time series representation model has been developed, which is conceived to support accurate and fast similarity detection. This model is called Derivative time series Segment Approximation (DSA), as it achieves a concise yet feature-rich time series representation by com- bining the notions of derivative estimation, segmentation and segment approximation. Uncertain Data | Research in uncertain data mining went into two di- rections. In a ¯rst phase, a new proposal for partitional clustering has been de¯ned by introducing the Uncertain K-medoids (UK-medoids) al- gorithm. This approach provides a more accurate way to handle uncertain objects in a clustering task, since a cluster representative is an uncertain object itself (and not a deterministic one). In addition, e±ciency issue has been addressed by de¯ning a distance function between uncertain objects that can be calculated o²ine once per dataset. In a second phase, research activities aimed to investigate issues related to hierarchical clustering of uncertain data. Therefore, an agglomera- tive centroid-based linkage hierarchical clustering framework for uncer- tain data (U-AHC) has been proposed. The key point lies in equipping such scheme with a more accurate distance measure for uncertain objects. Indeed, it has been resorted to information theory ¯eld to ¯nd a mea- sure able to compare probability distributions of uncertain objects used to model uncertainty. Text Data |Research results on text data can be summarized in two main contributions. The ¯rst one regards clustering of multi-topic documents, and a framework for hard clustering of documents according to their mix- tures of topics has been proposed. Documents are assumed to be modeled by a generative process, which provides a mixture of probability mass functions (pmfs) to model the topics that are discussed within any spe- ci¯c document. The framework combines the expressiveness of generative models for document representation with a properly chosen information- theoretic distance measure to group the documents. The second proposal concerns distributional clustering of XML documents, focusing on a the development of a distributed framework for e±ciently clustering XML documents. The distributed environment consists of a peer-to-peer network where each node in the network has access to a portion of the whole document collection and communicates with all the other nodes to perform a clustering task in a collaborative fashion. The proposed framework is based on modeling and clustering XML documents by structure and content. Indeed, XML documents are transformed into transactional data based on the notion of tree tuple. The framework is based on the well-known paradigm of centroid-based partitional clustering to conceive the distributed, transactional clustering algorithm. Biomedical Data | Research results on time series and uncertain data have been involved to support e®ective and e±cient biomedical data man- agement. The focus regarded both proteomics and genomics, investigat- Abstract vii ing Mass Spectrometry (MS) data and microarray data. In the speci¯c, a Mass Spectrometry Data Analysis (MaSDA) system has been de¯ned. The key idea consists in exploiting temporal information implicitly contained in MS data and model such data as time series. The major advantages of this solution are the dimensionality and the noise reduction. As re- gards micrarray data, U-AHC has been employed to perform clustering of microarray data with probe-level uncertainty. A strategy to model probe- level uncertainty has been de¯ned, together with a hierarchical clustering scheme for analyzing such data. This approach performs a gene-based clustering to discover clustering solutions that are well-suited to capture the underlying gene-based patterns of microarray data. The e®ectiveness and the e±ciency of the proposed techniques in clus- tering complex data are demonstrated by performing intense and exhaustive experiments, in which such proposals are extensively compared with the main state-of-the-art competitors.
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    Rheology of highly-concentrated-in-oil emulsions
    (2010) Lupi, Francesca Romana; De Cindio, Bruno
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    Chemical-physical characterization of complex systems: the case of pectins
    (2010-12-02) Checchetti, Andrea; De Cindio, Bruno
    In industrial process, separation of the hydrolyzed pectin solution is performed by centrifugal and filtration technologies. The effect of water addition to the hydrolyzed citrus peels slurry on the separation efficiency was investigated, with the aim to improve pectin recovery. Different dilution ratios were tested and it was found that the pectin recovery increases when increasing water addition passing through a maximum value. No relevant effects on pH and pectin yield were found when increasing the contact time between water and hydrolyzed slurry, confirming that no further progress of hydrolysis or extraction processes is caused by the dilution. Therefore, the increase in pectin recovery can be attributed only to the water addition. Intrinsic viscosity properties of commercial pectins and their mixtures in dilute solutions were investigated by using capillary viscometer. Influence of degree of esterification on interaction polymer-solvent was studied in order to provide additional evidence that can be used to elucidate the mechanism of the intermolecular interaction between two pectins and to determine their compatibility in dilute solutions. The viscosity measurements of ternary system have been performed by two techniques: 1. The first was determined by putting the polymer A and B with certain weight ratio in a pure solvent 2. The second was determined by putting the polymer A (referred to as guest or probe polymer) in solution in which the polymer B (referred to as host or matrix polymer) is found at a constant concentration. This technique is called the method of polymer solvent. By using the first method, two compatibility criteria, based on specific viscosity data and derived for synthetic polymers, have been applied to pectin mixtures at different degree of esterification (DE). Data revealed that positive molecular interaction take place when pectin in solution have a different DM (i.e. HM/LM mixtures), whilst an incompatible behavior was found for similar pectin (i.e. both HM and LM). In the case of incompatible pairs of pectin, also the apparent molecular weight of ternary solution showed an increase with respect to the additive mixing rule, due to repulsive forces. On the contrary, due to attractive forces in case of compatible pectin pairs, the molecular weight is lower than the calculated average. By using the polymer-solvent method, the coefficient (KAB) of interaction between polymers has been calculated. The analyzing of this parameter KAB allowed to justify the results obtained.
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    Applicazione della programmazione stocastica nella gestione delle sale operatorie
    (2011) Pirelli, Domenico; Conforti, Domenico; Bruni, Maria Elena; Grandinetti, Lucio
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    Scambi di conoscenza e flussi di capitale intellettuale nelle relazioni interorganizzative tra PMI
    (2011) Gitto, Davide Salvatore; Migliarese, Piero; Grandinetti, Lucio
    Il presente lavoro di tesi ha come obiettivo quello di esplorare il modo in cui relazioni interorganizzative (RI) e capitale intellettuale (CI) s’influenzano reciprocamente all’interno delle piccole e medie imprese (PMI). Lo scopo è di pervenire ad un modello concettuale non definitivo che aiuti a comprendere, da un lato come relazioni stabili e durature possano influenzare positivamente il capitale intellettuale e quindi le performance di una PMI, dall’altro come il capitale intellettuale di un’impresa (e i meccanismi implementati per gestirlo) possa a sua volta impattare sulla qualità delle relazioni collaborative da questa instaurate. L’ambizione della ricerca è evidentemente quella di identificare un insieme di meccanismi organizzativi, direttamente controllabili e attivabili dalle PMI, che consentano a queste di migliorare la propria attitudine e capacità collaborativa. La rilevanza della ricerca è comprovata dal notevole impatto che entrambi gli elementi oggetto di studio, RI e CI, hanno sulla competitività delle PMI. La crucialità delle relazioni collaborative, oltre ad essere stata dimostrata da un ampio filone in letteratura1, è testimoniata dal vivo interesse suscitato in ambito sia politico che comunitario e sfociato in numerose iniziative volte a favorire l’agglomerazione di PMI in forme reticolari d’impresa2. Anche la rilevanza del capitale intellettuale, oltre ad essere sancita a livello scientifico e accademico (Resource-based view, Knowledge-based view, ecc.) è stata riconosciuta a livello politico europeo mediante la stessa strategia di Lisbona. Il legame tra RI e CI è stato già in parte evidenziato in letteratura attraverso una serie di studi volti ad evidenziare come relazioni più o meno solide influenzassero gli scambi di conoscenza tra le parti coinvolte (Reagans and McEvily, 2003). Tuttavia, manca un inquadramento definito ed esaustivo che evidenzi come anche il capitale intellettuale dell’impresa incida sulla sua capacità collaborativa e, quindi, sulla qualità delle relazioni da essa attivabili. Il capitale intellettuale di un’impresa è un fattore generalmente controllabile e progettabile. Incentrare l’analisi sul ruolo che il CI dell’impresa ha sulla capacità di questa di instaurare solide relazioni interorganizzative, quindi, consente anche di superare i limiti che le attuali prospettive teoriche presentano in termini di carenza di indicazioni pratiche ed efficaci. Mentre, infatti, gli studi afferenti all’economic geography e alla regional science assumono la prossimità geografica come fattore causa del fenomeno collaborativo, le prospettive della social embeddedness e dei social network individuano nei rapporti sociali e nella forza dei legami interpersonali le determinanti chiave per solide e proficue relazioni interorganizzative. Tanto la prossimità geografica, quanto la social embeddedness e la forza dei legami, tuttavia, presentano scarsi livelli di controllabilità e progettabilità, essendo un elemento sostanzialmente casuale il primo e dei fattori essenzialmente individuali ed esogeni i secondi. Per affrontare la ricerca, considerata la complessità del tema trattato, si è optato per un approccio qualitativo-induttivo che consentisse di esplorare a fondo le relazioni di causa effetto tra RI e CI. La strategia di ricerca adottata, dunque, è stata quella del caso di studio multiplo. Sono state analizzate, in modo approfondito, 6 PMI operanti a Vibo Valentia e specializzate nella fornitura di impianti per il settore Oil & Gas. Attraverso la somministrazione di interviste aperte e semi strutturate, nonché l’impiego di ulteriori tecniche per la raccolta dei dati, si è esplorato a fondo il legame reciproco tra relazioni commerciali instaurate dalle imprese e capitale intellettuale appreso nel corso del tempo grazie a tali relazioni. L’analisi del campione ha consentito di elaborare un modello teorico non conclusivo che sembra illuminare adeguatamente il rapporto tra le due variabili esaminate. Il modello emerso prevede un’evoluzione reciproca e circolare, in cui relazioni stabili e durature con i clienti vengono utilizzate come fonte primaria di nuove conoscenze e competenze da parte delle imprese fornitrici, e a loro volta le nuove competenze apprese vengono impiegate proattivamente da parte di quest’ultime per creare e consolidare relazioni commerciali nuove e meno solide. Un ruolo fondamentale in questa dinamica è giocato dai meccanismi operativi di apprendimento implementati dalle imprese in esame. Una varietà di meccanismi diversi, infatti, sembra determinare una maggior velocità con cui il capitale intellettuale viene incrementato. Maggiori livelli di capitale intellettuale, a loro volta, consentono un’espansione ed un consolidamento più repentino delle relazioni commerciali, e una minore dipendenza da pochi clienti stabili e longevi come uniche fonti di apprendimento. Nonostante il carattere esplorativo della tesi di ricerca, il modello emerso sembra evidenziare come anche le PMI possano migliorare la propria capacità collaborativa attraverso l’implementazione deliberata ed intenzionale di opportuni meccanismi organizzativi. Il presente lavoro lascia ampio margine a potenziali sviluppi futuri, sia attraverso la possibilità di condurre nuovi casi di studio confermativi che indagini empiriche più quantitative. È consigliabile, inoltre, esplorare ulteriormente il tipo di meccanismi di apprendimento che è più opportuno impiegare in presenza di diverse componenti di capitale intellettuale e di diverse relazioni collaborative (clienti, fornitori, concorrenti).
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    Metodi euristici per la soluzione dello stochastic dial a ride problem
    (2011) Grande, Maria Grazia; Guerriero, Francesca; Grandinetti, Lucio
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    Models and Policies for Service Industries via Revenue Management
    (2011) Olivito, Filomena; Miglionico, Giovanna; Guerriero, Francesca; Grandinetti, Lucio
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    Modeling of biotechnological and food-industry processes
    (2011) Saraceno, Alessandra; De Cindio, Bruno; Curcio, Stefano
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    Non-conventional approaches to statical and dynamical analysis of geometrically nonlinear structure
    (2011) La Sala, Gabriella; Casciaro, Raffaele; Lopez, Salvatore
    The purpose of the work presented in this thesis is to implement two innovative approaches in order to analyze elastic instability problems both in statical and in dynamical eld. The proposed formulations have their main feature in the possibility of describing large rotations without the use of rotation matrices in order to overcome complex manipulations required to obtain conservative descriptions and well-posed transformation matrices. The basis is a total Lagrangian description, where the rigid body motions (translations and rotations) are separated from the total deformation that consequently can be treated using the small-deformation linearized theory. The principal di erence between the suggested two models concerns the chosen parameterization of nite rotations, with distances applied to twoand three-dimensional nite elements in the rst and slopes applied to two node nite element beams in the second one. The theoretical features of the the approaches are presented and their main items are discussed referring to some implementations to planar and spatial beam and thin plate models. An incursion into dynamics has also been performed. The present approach is featured by the fact that the formulation is simple, the expressions in the equations of the nonlinear system are explicit and computationally e cient, and the analysis is robust and economical. A large amount of numerical analysis is performed and the good agreement with the results reported in the literature shows the accuracy and capability of the proposed approaches for numerical implementations.
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