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1
BERNACCHIA, GIUSEPPE. "NONLINEAR OPERATORS FOR IMAGE PROCESSING: DESIGN, IMPLEMENTATION AND MODELING TECHNIQUES FOR POWER ESTIMATION." Doctoral thesis, Università degli studi di Trieste, 2000. http://thesis2.sba.units.it/store/handle/item/12679.
Повний текст джерелаАнотація:
1998/1999Negli ultimi anni passati le applicazioni multimediali hanno visto uno sviluppo notevole, trovando applicazione in un gran numero di campi. Applicazioni come video conferenze, diagnostica medica, telefonia mobile e applicazioni militari necessitano il trattamento di una gran mole di dati ad alta velocità. Pertanto, l'elaborazione di immagini e di dati vocali è molto importante ed è stata oggetto di numerosi sforzi, nel tentativo di trovare algoritmi sempre più veloci ed efficaci. Tra gli algoritmi proposti, noi crediamo che gli operatori razionali svolgano un ruolo molto importante, grazie alla loro versatilità ed efficacia nell'elaborazione di dati. Negli ultimi anni sono stati proposti diversi algoritmi, dimostrando che questi operatori possono essere molto vantaggiosi in diverse applicazioni, producendo buoni risultati. Lo scopo di questo lavoro è di realizzare alcuni di questi algoritmi e, quindi, dimostrare che i filtri razionali, in particolare, possono essere realizzati senza ricorrere a sistemi di grandi dimensioni e possono raggiungere frequenze operative molto alte. Una volta che il blocco fondamentale di un sistema basato su operatori razionali sia stato realizzato, esso pu6 essere riusato con successo in molte altre applicazioni. Dal punto di vista del progettista, è importante avere uno schema generale di studio, che lo renda capace di studiare le varie configurazioni del sistema da realizzare e di analizzare i compromessi tra le variabili di progetto. In particolare, per soddisfare l'esigenza di metodi versatili per la stima della potenza, abbiamo sviluppato una tecnica di macro modellizazione che permette al progettista di stimare velocemente ed accuratamente la potenza dissipata da un circuito. La tesi è organizzata come segue: Nel Capitolo 1 alcuni sono presentati alcuni algoritmi studiati per la realizzazione. Ne viene data solo una veloce descrizione, lasciando comunque al lettore interessato dei riferimenti bibliografici. Nel Capitolo 2 vengono discusse le architetture fondamentali usate per la realizzazione. Principalmente sono state usate architetture a pipeline, ma viene data anche una descrizione degli approcci oggigiorno disponibili per l'ottimizzazione delle temporizzazioni. Nel Capitolo 3 sono presentate le realizzazioni di due sistemi studiati per questa tesi. Gli approcci seguiti si basano su ASIC e FPGA. Richiedono tecniche e soluzioni diverse per il progetto del sistema, per cui é interessante vedere cosa pu6 essere fatto nei due casi. Infine, nel Capitolo 4, descriviamo la nostra tecnica di macro modellizazione per la stima di potenza, dando una breve visione delle tecniche finora proposte e facendo vedere quali sono i vantaggi che il nostro metodo comporta per il progetto.
In the past few years, multimedia application have been growing very fast, being applied to a large variety of fields. Applications like video conference, medical diagnostic, mobile phones, military applications require to handle large amount of data at high rate. Images as well as voice data processing are therefore very important and they have been subjected to a lot of efforts in order to find always faster and effective algorithms. Among image processing algorithms, we believe that rational operators assume an important role, due to their versatility and effectiveness in data processing. In the last years, several algorithms have been proposed, demonstrating that these operators can be very suitable in different applications with very good results. The aim of this work is to implement some of these algorithm and, therefore, demonstrate that rational filters, in particular, can be implemented without requiring large sized systems and they can operate at very high frequencies. Once the basic building block of a rational based system has been implemented, it can be successfully reused in many other applications. From the designer point of view, it is important to have a general framework, which makes it able to study various configurations of the system to be implemented and analyse the trade-off among the design variables. In particular, to meet the need far versatile tools far power estimation, we developed a new macro modelling technique, which allows the designer to estimate the power dissipated by a circuit quickly and accurately. The thesis is organized as follows: In chapter 1 we present some of the algorithms which have been studied for implementation. Only a brief overview is given, leaving to the interested reader some references in literature. In chapter 2 we discuss the basic architectures used for the implementations. Pipelined structures have been mainly used for this thesis, but an overview of the nowaday available approaches for timing optimization is presented. In chapter 3 we present two of the implementation designed for this thesis. The approaches followed are ASIC driven and FPGA drive. They require different techniques and different solution for the design of the system, therefore it is interesting to see what can be done in both the cases. Finally, in chapter 4, we describe our macro modelling techniques for power estimation, giving a brief overview of the up to now proposed techniques and showing the advantages our method brings to the design.
XII Ciclo
1969
Versione digitalizzata della tesi di dottorato cartacea.
2
CARINI, ALBERTO. "ADAPTIVE AND NONLINEAR SIGNAL PROCESSING." Doctoral thesis, Università degli studi di Trieste, 1997. http://thesis2.sba.units.it/store/handle/item/13000.
Повний текст джерела
3
FUSIELLO, ANDREA. "THREE-DIMENSIONAL VISION FOR STRUCTURE AND MOTION ESTIMATION." Doctoral thesis, Università degli studi di Trieste, 1999. http://thesis2.sba.units.it/store/handle/item/12451.
Повний текст джерелаАнотація:
1997/1998Questa tesi, intitolata Visione Tridimensionale per la stima di Struttura e Moto, tratta di tecniche di Visione Artificiale per la stima delle proprietà geometriche del mondo tridimensionale a partire da immagini numeriche. Queste proprietà sono essenziali per il riconoscimento e la classificazione di oggetti, la navigazione di veicoli mobili autonomi, il reverse engineering e la sintesi di ambienti virtuali. In particolare, saranno descritti i moduli coinvolti nel calcolo della struttura della scena a partire dalle immagini, e verranno presentati contributi originali nei seguenti campi. Rettificazione di immagini steroscopiche. Viene presentato un nuovo algoritmo per la rettificazione, il quale trasforma una coppia di immagini stereoscopiche in maniera che punti corrispondenti giacciano su linee orizzontali con lo stesso indice. Prove sperimentali dimostrano il corretto comportamento del metodo, come pure la trascurabile perdita di accuratezza nella ricostruzione tridimensionale quando questa sia ottenuta direttamente dalle immagini rettificate. Calcolo delle corrispondenze in immagini stereoscopiche. Viene analizzato il problema della stereovisione e viene presentato un un nuovo ed efficiente algoritmo per l'identificazione di coppie di punti corrispondenti, capace di calcolare in modo robusto la disparità stereoscopica anche in presenza di occlusioni. L'algoritmo, chiamato SMW, usa uno schema multi-finestra adattativo assieme al controllo di coerenza destra-sinistra per calcolare la disparità e l'incertezza associata. Gli esperimenti condotti con immagini sintetiche e reali mostrano che SMW sortisce un miglioramento in accuratezza ed efficienza rispetto a metodi simili Inseguimento di punti salienti. L'inseguitore di punti salienti di Shi-Tomasi- Kanade viene migliorato introducendo uno schema automatico per lo scarto di punti spuri basato sulla diagnostica robusta dei campioni periferici ( outliers ). Gli esperimenti con immagini sintetiche e reali confermano il miglioramento rispetto al metodo originale, sia qualitativamente che quantitativamente. Ricostruzione non calibrata. Viene presentata una rassegna ragionata dei metodi per la ricostruzione di un modello tridimensionale della scena, a partire da una telecamera che si muove liberamente e di cui non sono noti i parametri interni. Il contributo consiste nel fornire una visione critica e unificata delle più recenti tecniche. Una tale rassegna non esiste ancora in letterarura. Moto tridimensionale. Viene proposto un algoritmo robusto per registrate e calcolare le corrispondenze in due insiemi di punti tridimensionali nei quali vi sia un numero significativo di elementi mancanti. Il metodo, chiamato RICP, sfrutta la stima robusta con la Minima Mediana dei Quadrati per eliminare l'effetto dei campioni periferici. Il confronto sperimentale con una tecnica simile, ICP, mostra la superiore robustezza e affidabilità di RICP.
This thesis addresses computer vision techniques estimating geometrie properties of the 3-D world /rom digital images. Such properties are essential for object recognition and classification, mobile robots navigation, reverse engineering and synthesis of virtual environments. In particular, this thesis describes the modules involved in the computation of the structure of a scene given some images, and offers original contributions in the following fields. Stereo pairs rectification. A novel rectification algorithm is presented, which transform a stereo pair in such a way that corresponding points in the two images lie on horizontal lines with the same index. Experimental tests prove the correct behavior of the method, as well as the negligible decrease oLthe accuracy of 3-D reconstruction if performed from the rectified images directly. Stereo matching. The problem of computational stereopsis is analyzed, and a new, efficient stereo matching algorithm addressing robust disparity estimation in the presence of occlusions is presented. The algorithm, called SMW, is an adaptive, multi-window scheme using left-right consistency to compute disparity and its associated uncertainty. Experiments with both synthetic and real stereo pairs show how SMW improves on closely related techniques for both accuracy and efficiency. Features tracking. The Shi-Tomasi-Kanade feature tracker is improved by introducing an automatic scheme for rejecting spurious features, based on robust outlier diagnostics. Experiments with real and synthetic images confirm the improvement over the original tracker, both qualitatively and quantitatively. 111 Uncalibrated vision. A review on techniques for computing a three-dimensional model of a scene from a single moving camera, with unconstrained motion and unknown parameters is presented. The contribution is to give a critical, unified view of some of the most promising techniques. Such review does not yet exist in the literature. 3-D motion. A robust algorithm for registering and finding correspondences in two sets of 3-D points with significant percentages of missing data is proposed. The method, called RICP, exploits LMedS robust estimation to withstand the effect of outliers. Experimental comparison with a closely related technique, ICP, shows RICP's superior robustness and reliability.
XI Ciclo
1968
Versione digitalizzata della tesi di dottorato cartacea.
4
QUAIA, CHRISTIAN. "FROM VISION TO ACTION: A NEUROMIMETIC MODEL OF THE SACCADIC SYSTEM." Doctoral thesis, Università degli studi di Trieste, 2001. http://thesis2.sba.units.it/store/handle/item/12469.
Повний текст джерела
5
VLAHINIC, SASA. "LA MISURA DELLA DISTORSIONE ARMONICA E LE METODOLOGIE D'IDENTIFICAZIONE DELLE SORGENTI DI DISTURBO NELLA DETERMINAZIONE DELLA QUALITA' DELL'ENERGIA ELETTRICA." Doctoral thesis, Università degli studi di Trieste, 2003. http://thesis2.sba.units.it/store/handle/item/12763.
Повний текст джерела
6
FRANCO, ELISA. "A STABILIZING DISTRIBUTED RECEDING HORIZON CONTROL SCHEME FOR COOPERATIVE LINEAR AND NONLINEAR SYSTEMS." Doctoral thesis, Università degli studi di Trieste, 2007. http://thesis2.sba.units.it/store/handle/item/12283.
Повний текст джерела
7
Tampellini, Luca. "Interfaccia web per un sistema di condivisione semantica dell'informazione: studio e implementazione." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4385/.
Повний текст джерелаАнотація:
Questa tesi progettuale nasce per integrare gli sforzi attuali sullo sviluppo del web semantico.
La piattaforma di riferimento sulla quale è stato svolto il presente lavoro è SMART-M3. Questa piattaforma mette a disposizione uno spazio condiviso di informazioni, rappresentate e accessibili secondo le tecnologie del web semantico.
In questo scenario, nasce la necessità di disporre di un'interfaccia web capace di interagire con la piattaforma - in grado di risolvere la complessità intrinseca dei dati semantici - allo scopo di averne un completo controllo; ricerche precedenti a questo proposito hanno dato come frutto una libreria PHP che mi è stata consegnata come strumento per lo sviluppo dell'interfaccia.
La tesi si è articolata in 3 fasi principali: una fase iniziale di documentazione sull'argomento, eseguita principalmente sul libro “A developer's guide to the semantic web” di Liyang Yu e sulla tesi “Ontologie per il web semantico: un'analisi comparativa.” di Indrit Beqiri; una seconda fase, quella principale, di sviluppo del progetto informatico; una terza fase, infine, di sviluppo di questo elaborato di tesi, da considerarsi come la trattazione di tutto il percorso soprascritto, dall'inizio alla fine, secondo l'ordine cronologico in cui si svolto l'intero processo della tesi.
8
Aleo, Ignazio. "Complexity in motion." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1072.
Повний текст джерелаАнотація:
In the last few years a lot of works have been done in the field of motor control and in motion analysis. Several different hypotheses have been described and reviewed to understand living beings on motor coordination.
What is commonly referred to, as motor control is indeed an articulated problem that is, at least from a robotic perspective, often more suitably divided in: sensing (perception, cognition), deliberation, planning, kinematic control and dynamic control.
Through the pages of this work, several different problems related to motion control, to living beings motion and to its robotic counterpart will be addressed.
The strong underling motif of all the proposed algorithms and architectures (both software and hardware) is the presence of a real environment interaction.
From reflexes to motion planning, from architecture definition to smart sensor design and from kinematic modelling of the human body to the action-perception loop implementation, this thesis intends to be a first gatherer of information and ideas in this interesting and complex field.
9
La, Malfa Salvatore. "Rtd fluxgate magntometers." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1079.
Повний текст джерелаАнотація:
Fluxgate magnetometers have always been of interest to the technical and scientific communities as practical and convenient sensors for vector magnetic field measurements in the range of microtesla requiring a resolution of hundreds of picotesla at room temperature, and they find applicability in fields such as space, geophysical exploration and mapping, non destructive testing, as well as assorted military applications. In this Thesis the research work on RTD Fluxgate is presented along with the development of models, prototypes and their characterization.
Classical but also new technological approaches to realise low-cost Fluxgate magnetometers are proposed.
The design, development and characterization of an integrated mixed signal circuit expressly designed to read out the magnetic field information, and alternative readout strategies have also been described.
10
Saccullo, Giuseppe. "Advanced Ecocomposites Materials." Doctoral thesis, Università di Catania, 2019. http://hdl.handle.net/10761/4150.
Повний текст джерелаАнотація:
The thesis is divided into five chapters: the first four chapters cover the state of the art review on wood plastic composites, lignin and the recycling of bioplastics. The fifth chapter cover the experimental work of the thesis. In chapter fifth the materials and methods used are firstly presented followed by the discussion on the results obtained.
The research work performed during the PhD was focused on the development of novel eco-compatible thermoplastic composites. The experimental work was based on the use of two polymer matrices: polypropylene and poly(lactid acid). Polypropilene is not biodegradable but by the addition of a lignin based polymer the carbon biocontent was increased obtaining a formulation readily available and suitable for applications. The results presented on these blends outlined an increased thermal stability and mechanical resistance due to the addition of the lignin based system. This result is promising for the application of this blend in the automotive field. Many automotive parts, such as for example the under hood parts, require improved thermal performances that can be fulfilled by the proposed approach.
To overcome the problem of the use of petroleum based plastic the use of PLA was investigated in the research. PLA can be synthetized starting from sugar resulting in a ecofriendly matrix. PLA can be composted so it is a viable option to improve the ecocompability of polymers. However, PLA has an high cost of production which, since now, limited its acceptance in mass production. Therefore, to reduce PLA cost and, at the same time, improve the mechanical and thermal properties the addition of lignin was studied. The results obtained showed that, as for PP, lignin is a potentially good additive. However, the results showed some processing issues due to the thermal stability of PLA which was negatively affected by the reactive moiety of lignin.
The results obtained confirmed that combining natural fillers (i.e. lignin) with polymers synthetized by natural sources (i.e. PLA) promising blends can be obtained. However, processing should be optimized to minimize the degradation. To achieve such goal, a feasible process could be to chemical modify the lignin structure or the PLA matrix. Lignin is a multifunctional polymers thus, the approach could be oriented to link moiety which can reduce the interaction with the ester group of PLA.
In addition to the improvement of the thermal stability of PLA/Lignin blends future work will be oriented to the use of such blends as matrix for natural fiber composites. This further development will be pursued to obtain sytems suitable for structural applications.
11
PIUZZI, BARBARA. "NUOVO APPROCCIO AL BIOMONITORAGGIO: SVILUPPO DI STRUMENTAZIONE INNOVATIVA BASATA SU BIOSENSORI." Doctoral thesis, Università degli studi di Trieste, 2007. http://thesis2.sba.units.it/store/handle/item/12284.
Повний текст джерела
12
Gambuzza, Lucia Valentina. "Memristors and networks: new structures for complexity." Doctoral thesis, Università di Catania, 2014. http://hdl.handle.net/10761/1481.
Повний текст джерелаАнотація:
One of the most interesting aspects of complexity is that it occurs at
different levels. It may occur at the level of interactions among the
agents that compose a complex network: despite the relatively simple
behavior of each single unit, the whole network may exhibit holistic
collective dynamics, such self-organization, synchronization, robustness
to failure, and so on; and it may occur, in the form of an aperiodic
irregular behavior, at the level of a system described by a low-order set
of ordinary differential equations, three, for instance, in the case of
continuous-time systems. This thesis focuses on both levels of complexity.
The first part, in particular, deals with complexity at the level of a
single dynamical system. The main contributions of the work summarized in
this thesis refer to the use of a new electronic component for the design
of chaotic circuits. This new component, the memristor, is at the same
time a memory element and a nonlinear element and for this reason has been regarded in literature as an effective block to reduce the minimum number of components needed to build a chaotic circuit. The original aspect of this thesis is the focus on a realistic model of memristor, that is a
model derived starting from the analysis of the real memristor device
discovered in the HP laboratories. The use of such approach introduces
constraints in the design that are not considered in idealized models such
as piece-wise linear ones. The main results were: i) the introduction of a
configuration of two memristors in antiparallel which has been used as the
fundamental block to design a gallery of autonomous and non-autonomous
nonlinear circuits exhibiting a rich dynamics, including chaos; ii) the
design of a hybrid circuit which takes from the characterization
methodology of real memristors the idea of using a simple digital linear
control circuitry which allows chaos to be observed with the driving of a
single memristor.
The second part of the thesis focuses on synchronization on complex
networks. In particular, the onset of a new form of synchronization, named
remote synchronization, in complex networks has been investigated. Remote synchronization appears in star-like networks of coupled Stuart-Landau oscillators, where the hub node is characterized by an oscillation
frequency different from that of the leaves, as a regime in which the
peripheral nodes are synchronized each other but not with the hub. In this
thesis we have investigated if similar conditions can be observed in more
general frameworks. We have found that networks of not homogeneous nodes may display many pairs of nodes that, despite the fact that are not
directly connected nor connected through chains of synchronized nodes, are phase synchronized.
We have introduced measures to characterize this phenomenon and found that it is common both in scale-free and Erdos-Renyi networks. Furthermore, this is an important mechanism to form clusters of
synchronized nodes in a network. Finally, we have linked the
appearance of pairs of remotely synchronized nodes to a topological
condition of inhibition of direct paths or paths through chains of
synchronized nodes, thus elucidating a mechanism which has lead to the
definition of a series of topologies where remote synchronization is
found.
Finally, we have explored the use of memristor as a synapse for complex
networks. Also in this case, we have used a configuration of two HP
memristors and shown that such configuration provides an adaptation rule
for the links of a complex network, enabling the emergence of a set of
weights leading to synchronization.
13
Pellegrino, Antonio. "Metodi sperimentali per la caratterizzazione di schiume sintattiche e leghe metalliche ad elevato strain rate." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1109.
Повний текст джерелаАнотація:
Il presente lavoro di tesi riguarda la caratterizzazione a differenti strain rate di diverse tipologie di materiali impiegati in ambito aerospaziale e le problematiche sperimentali ad essa connesse.
Tale lavoro si inserisce nell¿ambito dell¿attività svolta dall¿Impact Engineering Lab dell¿Università di Oxford durante il periodo di formazione all¿estero della durata di un anno svolto sotto la supervisione del Dr. Nik Petrinic e del Dr. Vito Tagarielli ed è frutto della stretta attività di collaborazione tra il laboratorio suddetto ed una nota multinazionale operante nel settore aerospaziale.
All¿interno del lavoro di tesi vengono descritte accuratamente le differenti modalità di test relative ai test sui differenti materiali, le diverse e talvolta opposte problematiche inerenti i test su materiali polimerici e su materiali dotati di particolare resistenza, la definizione della geometria dei provini, l¿utilizzo dei vari equipaggiamenti impiegati, inclusa la messa a punto e la sincronizzazione dei segnali provenienti dalle diverse macchine di prova utilizzate e le telecamere ad elevato frame rate. Vengono inoltre discusse le modalità di elaborazione dei dati rilevati ed i risultati ottenuti a differenti velocità di deformazione valutando le variazioni di
comportamento meccanico del materiale in termini di proprietà elastiche, plastiche e di duttilità.
La totalità dei test illustrati è stata eseguita ricorrendo sia a misure di tipo
estensimetrico sia a misure di tipo ottico utilizzando opportune lenti di tipo
telecentrico e telecamere ad elevato frame rate. Inoltre, allo scopo di comprendere i meccanismo di deformazione e rottura di uno dei materiali caratterizzati si sono effettuate delle micrografie utilizzando un microscopio a scansione elettronica ESEM (Electon Scansion Environmental Microscope) ed analizzando visivamente lo stato delle superfici di rottura di provini testati in tensione e compressione a strain rate differenti.
14
Ventura, Cristina. "Theoretical and Experimental Development of a Photovoltaic Power System for Mobile Robot Applications." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1102.
Повний текст джерелаАнотація:
The primary goal of this work is the theoretical and experimental development of micro and mini systems for the photovoltaic production and the energy storage.
Robotics platforms should be, as much as possible, autonomous and self-sufficient, also from the energetic point of view. To this aim, up to now, the best compromise appears to be the use of micro solar power systems with rechargeable batteries. The use of this strategy for supplying systems with limited size and mass, but nevertheless high power requirements, such as a mobile robot, has been first studied. The system taken as test-bed in the experiment is a bio-inspired mobile robot, called TriBot.
First of all, a preliminary analysis of the feasibility of a photovoltaic system with batteries to supply this mobile robot has been done, considering the different solutions to place the PV cells on the robot structure, the different photovoltaic technologies and the power consumption of the robot, the conclusion is that, using the photovoltaic system here proposed, it is possible to increase the autonomy of the robot.
Since in the PV system here analyzed few solar cells can be employed, a very efficient charging system is an essential requisite. To this aim, a novel photovoltaic charge regulator, which uses the Fractional Open-Circuit Voltage MPPT method, is proposed.
A typical stand-alone photovoltaic system includes a solar array, batteries, regulator and load. In order to model the whole system and to evaluate its performance, a Simulink model in Matlab environment has been developed. In the simulator, measured values of the radiation and the temperature have been used, Anyhow, it will be possible also to use predicted values of radiation and temperature.
In this work, data given us by a weather forecast provider have been used. First of all the accuracy of these predicted data have been determined. Then, a method to classify each minute of a day as variable, cloudy, slightly cloudy or clear has been implemented. Using a neural network, a correlation between the classification of a specific day and the error done has been found. The knowledge of the available energy, in fact, should allow to implement power saving strategies, optimizing the activities of the robot.
Forecast and measured solar radiation are relative to the horizontal plane. However, the PV panel exposition is not assumed to be a control variable due to the fact that the robot can change its posture operating on uneven terrains. For these reasons, models are required to estimate the solar radiation on the plane of the PV array starting from the radiation on the horizontal plane. To this aim, Perez and Klucher models have been developed, these models require information at the same time on the global and the direct or diffuse radiation on the horizontal surface. Moreover, a neural network that allows to evaluate the global solar radiation on the tilted surface directly from the global solar radiation measured on the horizontal plane, without the need to slit it into the direct and diffuse components, has been developed.
Once that the solar radiation, measured or forecast, at any inclination and orientation are estimated; the power consumption of the robot and the efficiency of the charge regulator are known, all these information can be used in the Simulink model that, therefore, can become a very helpful tool to estimate the power production of the photovoltaic system and therefore the increase of the autonomy of the embedded systems used as load.
15
Belluomo, Paola. "New proposals for EEG and fMRI based Brain Computer Interface technology." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1305.
Повний текст джерелаАнотація:
In this manuscript three related aspects of research on BCI systems were discussed. These aspects were the evaluation of a nonlinear feature extraction algorithm for BCI, the analysis of the functional connectivity between the signals acquired in different brain regions when a user performs an operant conditioning paradigm with fMRI based BCI technology, and the development of BCIs applications for disabled subjects.
We have introduced a new EEG signals features extraction techniques based on nonlinear time series analysis. This signal processing approach was tested offline considering three sessions of imaginary motor tasks. The main objective is increasing the performance of BCI systems extracting a more robust feature. In order to reach this objective a fast algorithm that computes the largest Lyapunov exponent, the DivA [7], was used. This implementation results to be computationally less onerous than the conventional ones, since it is not based on the time-delay embedding concept and also no intermediate computational steps are needed to obtain the final result. For this reason the DivA is particularly suitable for real time analysis, thus for BCI applications. Our evaluations underline the capability and the potentiality of this method in respect to the classical approach. The idea for future works is to integrate the nonlinear algorithm investigated in this thesis in a BCI system, thus using it on line. The design of a BCI based on our nonlinear feature extraction method could improve the performance of the systems that use sensory motor rhythms as neurophysiologic signals.
The analysis of the functional connectivity between brain regions involved in the perception of pain is the second topic that were dealt with in this thesis. Thanks to the collaboration with the central institute of mental health, Heidelberg university in Mannheim, the dataset recorded with an fMRI based BCI technology have been analysed. The results reveal the possibility for a person to modulate the brain waves, in particular the neurophysiologic signals related to the perception of pain. Control over the pain modulatory system is an important target because it could enable a unique mechanism for clinical control over pain. Here, we found that using real-time functional MRI based BCI to guide training, subjects were able to learn to control activation both in anterior cingulated cortex and in the posterior insula. The BCI techniques could have an important role for treating disease, for example for the chronic pain treatment. An aspect that can be investigated in future work is the involvement of the medial cingulate cortex in the pain perception. Indeed when the subject deliberately induced increases or decreases in ACC or pIns fMRI activation, there was a corresponding change in the connection between the MCC and the other ROIs. In particular a more strong connection between MCC and pInsR can be noticed. In future works could be interesting to analyze the role of MCC in the perception of pain.
Finally, we proposed the designs of different EEG based BCI applications. We aim to provide a significant quality of life improvement to users with severe disabilities. All the applications designed have been tested for able-bodied users, the future idea is to test the applicability of such tools also for the locked-in patients.
16
Termini, Pietro Savio. "Insect brain modeling for cognitive robotics." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1304.
Повний текст джерелаАнотація:
During his history, man has always tried to imitate nature, to better know and understand himself.
Thanks to the improvement of electronic technologies, the instruments with which he has followed this target have been improved, with results more and more realistic. Trying to artificially reproduce what nature has slowly realized and time tested, humans find amazing problems and solutions, that give a contribution to their life quality. Robots are the way humans try to reproduce animals, and study their interaction with the environment. Robots help to better know animals and animals help to create efficient robots. Analyzing animal brains leads to new control systems that could allow robots to be able to orient themselves, to take decisions, to survive alone, to complete dangerous missions, to be completely autonomous. Robot implementation could also lead to predictions, for basic science, deriving from emergent properties of models.
The goal of this work is to design and simulate a simplified model of the brain of the Drosophila melanogaster.
Fly has a small brain that shows a wealth of complex behaviors. Genetic techniques allow to remove parts of the Drosophila brain and the analysis of mutants behavior can lead to hypotheses about the functions of every single brain part.
The bio-inspired models have been implemented in robotic structures and in robot simulators, in order to make comparisons between the real fly and the modeled one. This PhD research has been oriented toward two main lines: the first one has been directed to the insect brain modeling;
the second line has been oriented to the simulation and the implementation of the model in robotic structures and then to the analysis of the behavior of the robots in order to obtain comparative results with real flies as well as predictions about the behavior of the real flies under particular circumstances.
This thesis is divided in seven chapters. The first four chapters describe an original robotic architecture inspired by
the fruit fly \emph{Drosophila melanogaster}. In the last three chapters, instead,
one peculiar part of the insect brain, the Mushroom Bodies, is analyzed and modeled.
This structure presents a lot of interesting capabilities and it deserves attention and investigation.
Biological details will be given step by step, in order to emphasize the link between
biology and models
17
Di, Salvo Roberto. "Large scale ground truth generation for performance evaluation of computer vision methods." Doctoral thesis, Università di Catania, 2014. http://hdl.handle.net/10761/1493.
Повний текст джерелаАнотація:
In this thesis a set of novel video annotation methods for performance evaluation of object detection, tracking and recognition applications is proposed.
Large scale labeled datasets are of key importance for the development of automatic video analysis tools as they, from one hand, allow multi-class classifiers training and, from the other hand, support the algorithms evaluation phase. This is widely recognized by the multimedia and computer vision communities, as witnessed by the growing number of available datasets; however, the research still lacks in usable and effective annotation tools, since a lot of human effort is necessary to generate high quality ground truth data. However, it is not feasible to collect large video ground truths, covering as much scenarios and object categories as possible, by exploiting only the effort of isolated research groups.
For these reasons in this thesis we first present a semi-automatic stand-alone tool for gathering ground truth data with the aim of improving the user experience by providing edit shortcuts such as hotkeys and drag-and-drop, and by integrating computer vision algorithms to make the whole process automatic with a little intervention by the end users. In this context we also present a collaborative web-based platform for video ground truthing which integrates the stand-alone tools and provides an easy and intuitive user interface that allows plain video annotation and instant sharing/integration of the generated ground truths, in order not to only alleviate a large part of the effort and time needed, but also to increase the quality of the generated annotations.
These tools are specifically thought to help users in collecting annotations thanks to the introduction of simple interfaces, which considerably improve and facilitate their work, also by integrating novel methods for quality control, but still remain a burdensome task with regard to the attention and time needed to obtain good records.
To motivate the users and relieve them from the tiresome task of making manual annotations, we devised strategies to automatically create annotation by processing data from the crowd. To this end we initially develop an approach based on an online game to collect big noisy data. By exploiting the information, we then propose data-driven approaches, mainly based on image segmentation and statistical methods, which allow us to obtain reliable video annotations by using low quality and noisy data gathered quickly and easily from the game. Also we demonstrate that the quality of the obtained annotations increases as more users play with the game making it an effective and valid application for the collection of consistent ground truth data.
18
Amenta, Valeria Assunta. "Study of an innovative non intrusive load monitoring system for energy emancipation of domestic users: hardware and ICT optimized solutions." Doctoral thesis, Università di Catania, 2017. http://hdl.handle.net/10761/3641.
Повний текст джерелаАнотація:
Non-intrusive appliance load monitoring (NIALM) is the process of disaggregating a household s total electricity consumption into its contributing appliances. Smart meters are currently being deployed on national scales, providing a platform to collect aggregate household electricity consumption data. Existing approaches to NIALM require a manual training phase in which either sub-metered appliance data is collected or appliance usage is manually labelled. This training data is used to build models of the household appliances, which are subsequently used to disaggregate the household s electricity data. Due to the requirement of such a training phase, existing approaches do not scale automatically to the national scales of smart meter data currently being collected.
In this thesis an unsupervised disaggregation method is presented which, unlike existing approaches, does not require a manual training phase. A NIALM system reads real-time data from a smart meter, usually positioned at the point on the public electricity network at which the customers is connected, and uses algorithms not only to quantify how much energy is used in the home, but also to determine what main devices are being operated. NIALM algorithms need a complete load signature and complex optimization algorithms to find the right combination of single loads that fits the real electrical measurements. It is practically impossible to get the detailed signature of all appliances inside a house/building and sophisticated optimization algorithm are not suitable for on-line applications. To do so, we address the following topics.
First, a straightforward NIALM algorithm is proposed, it is based on both a simple load signature, rated active and reactive power and a heuristic disaggregation algorithm.
Second, on real applications, this approach cannot reach very high performances; this is the reason why an active involvement of users is considered. The users feedback aims to: correct the load signatures, reduce the error of disaggregation algorithm and increase the active participation of users in saving energy politics.
Third, the NIALM algorithm has been accurately tested numerically using as input load curves generated randomly but under given constraints. In this way, the causes of inefficiency of the proposed approach are quantitatively analyzed both separately and in different combinations.
The above contributions provide a solution which satisfies the requirements of a NIALM method which is both unsupervised (no manual interaction required during training) and uses only smart meter data (no installation of additional hardware is required). When combined, the contributions presented in this thesis represent an advancement in the state of the art in the field of non-intrusive appliance load monitoring, and a step towards increasing the efficiency of energy consumption within households.
19
Buzzanca, Marco. "Sociality in Complex Networks." Doctoral thesis, Università di Catania, 2018. http://hdl.handle.net/10761/3766.
Повний текст джерелаАнотація:
The study of network theory is nothing new, as we may find the first example of a proof of network theory back in the 18th century. However, in recent times, many researchers are using their time to investigate networks, giving new life to an old topic. As we are living in the era of information, networks are everywhere, and their complexity is constantly rising. The field of complex networks attempts to address this complexity with innovative solutions. Complex networks all share a series of common topological features, which revolve around the relationship between nodes, where relationship is intended in the most abstract possible way. Nonetheless, it is important to study these relationships because they can be exploited in several scenarios, like web page searching, recommender systems, e-commerce and so on. This thesis presents studies of sociality in complex networks, ranging from the microscale, which focuses the attention on the point of view of single nodes, to the mesoscale, instead shifts the interest in node groups.
20
Cammarata, Massimiliano. "Progetto degli edifici a quasi zero energia." Doctoral thesis, Università di Catania, 2016. http://hdl.handle.net/10761/3774.
Повний текст джерелаАнотація:
A seguito della direttiva europea 31/2010/ce e della Legge 90/2013 i nuovi edifici dovranno essere a quasi zero energia a partire dal 2021. Il lavoro esamina le problematiche sia di involucro che impiantistiche di questi edifici e propone un metodo dinamico per il calcolo dei consumi energetici mensili, stagionali ed annuali.
21
Cavallo, Marco. "H2F: a hierarchical Hadoop framework to process Big Data in geo-distributed contexts." Doctoral thesis, Università di Catania, 2018. http://hdl.handle.net/10761/3801.
Повний текст джерелаАнотація:
L ampia diffusione di tecnologie ha portato alla generazione di enormi quantità di dati, o di Big Data, che devono essere raccolti, memorizzati e elaborati attraverso nuove tecniche per produrre valore nel modo migliore. I framework distribuiti di calcolo come Hadoop, basati sul paradigma MapRe-
duce, sono stati utilizzati per elaborare tali quantità di dati sfruttando la potenza di calcolo di molti nodi di cluster.
Purtroppo, in molte applicazioni di big data, i dati da elaborare risiedono in diversi data center computazionali eterogeni e distribuiti in luoghi diversi.
In questo contesto le performance di Hadoop crollano drasticamente. Per affrontare questo problema, abbiamo sviluppato un Hierarchical Hadoop Framework(H2F) in grado di pianificare e distribuire task tra cluster geograficamente distanti in modo da ridurre al minimo il tempo di esecuzione complessivo delle applicazioni.
Le nostre valutazioni sperimentali mostrano che l utilizzo di H2F migliora notevolmente il tempo di elaborazione per dataset geodistribuiti rispetto ad un semplice sistema Hadoop.
22
Corradino, Claudia. "Hybrid System of Systems Control : the TOKAMAK scenario." Doctoral thesis, Università di Catania, 2018. http://hdl.handle.net/10761/3820.
Повний текст джерелаАнотація:
The basic definition of System-of-Systems (SoS) is that of a large-scale
integration of many independent, self-contained systems having the
common aim of satisfying a global need. Under this perspective, lots of
systems of systems can be found in several fields where a common final
goal drives systems towards a final SoS state. In nuclear fusion research
area, several examples of SoS applications can be made. From the integration
of all the constituents of the TOKAMAK machines which work
together to achieve a sustained nuclear fusion reaction, to the circuits
made of active analogue components mimicking plasma behavior, to
the neural networks made of connected units working together in order
to predict plasma variables behavior. In this work, investigation of
several SoS relevant in TOKAMAK scenario is performed and interesting
results enhancing the plant capabilities provided. This thesis itself
has been structured with a SoS-like structures where the integration of
self-contained chapters is performed in order to satisfy the global goal
that is improving TOKAMAK performances.
23
Leotta, Marco. "Context Awareness in the Internet of Things and its Applications." Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/3938.
Повний текст джерелаАнотація:
In the last decade the role of context awareness, traditionally focused on human to machine interaction, has broadened its perspectives to the machine to machine paradigma. The main goal of this dissertation is both to understand how to apply context awareness to situations , perceived by smart devices, and to conceptually stretch context modeling to a dynamic contextualization in human to machine interactions.
The roots of the Internet of Things paradigma reside in the efforts reached in the Wireless Sensor Networks technology, mostly in data aggregation and in energy saving, and the adoption of multi-agent modeling has gained context awareness application to machine to machine interaction. A well defined methodology, previously applied to human to machine interaction, now can be adopted for smart devices, that behave like humans.
Another evidence of the emergence of the Internet of Things technology nowadays comes from the everyday life experience. The Internet of Things is the key for the practical implementation of innovative software systems for the ubiquitous computing. Thanks to all these technologies, Smart devices (like the Nest Thermostat or the Apple Watch) are currently more and more integrated among them and they are becoming invisible servants for final users. As a proof of this new technological era, we can think about how the usage of the Siri tool has become an automated and unconscious mechanism in looking for a telephone number, in reaching a specific destination, or in driving home heating, to understand the potentialities of merging context awareness to the Internet of Things in a convergent and ubiquitous platform.
The enormous amount of smart devices, currently deployed in the world, have also to deal with an easy knowledge representation of sensed context, in order to provide new mechanisms to automate daily tasks, understanding the behavior of end-users within the surrounding environment.
On the other hand, the rapid growing number of smart devices deployed has a drawback in the future proliferation of high level context models, possibly coupled to lower context levels.
What emerges from the current study is the necessity to easy the management of multiple contexts, to be used by upper level applications. The dynamic contextualization solves this kind of issues, distinguishing from the total amount of features, captured from the surrounding environment, and the context model that is closely related to the issue to be solved.
Deep profiling on context aware usage enhances the development of context aware services, that can simply use an abstraction layer to properly manage underlying context models. What can be deduced is that the customization of context aware services to the user is a key process to narrow the gap between smart devices and their daily usage.
In this dissertation, the definition of high level scenarios have been determined by applying decision trees, for their huge potentialities expressed in dynamic context extraction.
Applications of these concepts were used in developing management systems, addressed to an audience of experienced surgeons in breast cancer, covering surgical suggestions. The formal analysis of multiple datasets (related to the diagnosis of breast cancer), using interactive and navigable decision trees, showed the enormous potentialities of the system, both in knowledge representation (and its spreading), and in the identification of the context, considering the related decision support system mechanisms.
The conclusion of the research activity considers the emergence of context awareness in a future world, more and more full of smart devices connected among them, as an adaptive paradigm, for intra device optimizations and for final users application level benefits.
24
Maiorca, Felice. "Innovative Electromechanical Transduction Mechanisms for Piezoelectric Energy harvesting from Vibration: Toward Micro and Nano Electro-Mechanical Systems." Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/3949.
Повний текст джерелаАнотація:
Vibration energy harvesting is one the hottest topics addressed by a big part of the scientific community. A lot of transduction mechanisms have been investigated and designed, based mechanical systems and transduction principles in order to recover energy coming from environmental vibrations. In this work, innovative transduction mechanisms will be described, suitable to harvesting energy from weak random vibrations, to rectifying and multiplying voltages avoiding the use of classic solutions based on diodes. Innovative devices will be introduced, based on nonlinear mechanical systems and piezoelectric transducers; analytical models will be provided and simulation results will be shown. Laboratory prototypes and experiments will be also described. Comparisons between simulations and experiments results will be provided in order to demonstrate the goodness of the proposed approaches. Finally, MEMS technologies suitable with piezoelectric energy harvesting, together with a very simple micro scale prototype, will be introduced as encouraging elements for future miniaturization of the devices.
25
Ognibene, Giulia. "Multifunctional nanocomposites obtained by hierarchical structures." Doctoral thesis, Università di Catania, 2017. http://hdl.handle.net/10761/3980.
Повний текст джерелаАнотація:
Il presente lavoro è focalizzato sullo sviluppo di nanocompositi multifunzionali innovativi basati sull'uso di una struttura gerarchica. A questo scopo, nanofibre polimeriche sono state prodotte per electrospinning. Questo processo utilizza un' alta tensione (circa il 10-20 kV) per caricare elettricamente una soluzione polimerica per la produzione di fibre ultra-sottili. Due diverse applicazioni sono stati proposte per le membrane termoplastiche ottenute. Nella prima, esse sono state utilizzate per fabbricare laminati compositi tenacizzati e nanorinforzati (utilizzando MWCNT) mediante Resin Transfer Molding (RTM) e altre tecniche di infusione. Mentre nella seconda applicazione, tali membrane sono state modificate con nanoparticelle inorganiche e utilizzate come membrane attive per filtrazione dell'acqua.
La necessità di tenacizzare materiali compositi si pone perché essi sono soggetti a delaminazione lungo piani interlaminari. La soluzione proposta a questo problema è stato l'uso di nanofibre che possono essere abbastanza piccole da rinforzare regioni della matrice che si trovano tra strati adiacenti del laminato. A questo scopo sono stati elettrofilati diversi polimeri e sono stati utilizzati come tenacizzanti in laminati compositi. La caratterizzazione di questi laminati, modificati con nanofibre, mostra proprietà termo-meccaniche simili a quelle dei sistemi ottenuti utilizzando la procedura standard. Inoltre, al fine di conferire altre funzionalità quali resistenza al fuoco, lightining-strike, auto-sensing, ecc al composito, sistemi di resine epossidiche con nanocariche sono stati studiati e caratterizzati.
Parlando di membrane per la filtrazione dell'acqua, attualmente, membrane polimeriche sono per lo più utilizzate per applicazioni di filtraggio grazie alle loro buone proprietà e bassi costi rispetto alle membrane inorganiche. Di conseguenza, i meccanismi di filtrazione di queste membrane si basano principalmente sugli effetti meccanici come setacciatura, quindi nessuna rimozione chimica delle sostanze tossiche può essere realizzata, questo porta ad effetti di fouling che limitano le prestazioni della membrana. L'idea è stata quella di sviluppare le membrane attive per il filtraggio dell'acqua, caratterizzate da un effetto combinato, setacciatura, proprietà foto-catalitiche e proprietà antibatteriche. A questo scopo, nanofili di ZnO cristallino sono stati cresciuti con un processo chimico da un bagno di deposizione sulle fibre PES ES. Le membrane ibride ottenute mostrano una buona attività fotocatalitica. Inoltre, membrane di PES antibatteriche sono state ottenute da un procedimento one step a partire da una soluzione polimerica con nanoparticelle d'argento precursori. La conversione da precursori argento a nanoparticelle di argento è confermata dalla spettroscopia UV-vis.
26
Pulvirenti, Mario. "Fault tolerant solutions for ac multidrive systems." Doctoral thesis, Università di Catania, 2016. http://hdl.handle.net/10761/4017.
Повний текст джерелаАнотація:
Questa tesi, presenta uno studio riguardante sistemi in cui operano più azionamenti elettrici, i quali possono essere collegati in modo da definire un sistema multi-drive. In questo modo, una nuova topologia tollerante ai guasti è stata sviluppata e verificata sperimentalmente, in cui i drive sani supportano quelli guasti, evitando interruzioni che potrebbero essere critiche per motivi di sicurezza o economiche. La valutazione delle performance e dell efficienza durante le operazioni dopo il guasto è realizzata con sistemi multi-drive con due o tre azionamenti elettrici. Il sistema multi-drive composto da due azionamenti, di cui uno rotante e l altro statico, è usato anche per analizzare un sistema di generazione eolica.
Un ulteriore aspetto analizzato, riguarda la stima corretta della posizione di rotore di un singolo azionamento elettrico, presente in un sistema multi-drive, con sensori a bassa risoluzione. A causa di guasti che possono accadere su tali sensori, un opportuna tecnica di compensazione è presentata e verificata con tre diversi algoritmi.
27
Zago, Vito. "Smoothed Particle Hydrodynamics method and flow dynamics: the case of lava numerical modeling and simulation." Doctoral thesis, Università di Catania, 2019. http://hdl.handle.net/10761/4145.
Повний текст джерелаАнотація:
Lo Smoothed Particle Hydrodynamics è un metodo Lagrangiano mesh-free che sta riscuotendo interesse nel campo della fluidodinamica computazionale. Grazie alla sua natura, il metodo SPH è in grado di gestire fluidi complessi caratterizzati da reolgie non-Newtoniane, superfici libere, dipendenze dalla temperatura, transizioni di fase, grandi deformazioni, e così via. Il metodo SPH è caratterizzato da una natura intrinsecamente parallela, che ne rende possibile l'esecuzione su hardware per il calcolo parallelo ad alte prestazioni, come ad esempio le moderne schede grafiche (GPU), ottenendo così tempi di simulazione vantaggiosi. In questa tesi lavoreremo su GPUSPH, un'implementazione su GPU del metodo SPH. Studieremo la simulazione di un fluido molto complesso: la lava. La combinazione di superficie libera, topografia naturale, transizioni di fase e la formazione di strutture come argini e tunnel, rende la modellazione e la simulazione della lava un aspetto di interesse nel campo della fluidodinamica computazionale, con un notevole impatto in numerosi campi dell'Ingegneria e della ricerca scientifica. Vedremo l'introduzione in GPUSPH di modelli e strategie che permetteranno di trattare le diverse caratteristiche delle colate laviche, includendo lo sviluppo di uno schema di integrazione semi-implicito, che permetterà la simulazione di fluidi altamente viscosi, assicurando robustezza e riducendo i tempi di simulazione.
La nuova implementazione sarà testata per verificarne la correttezza e studiarne i livelli accuratezza e performance raggiunti.
28
Pin, Gilberto. "Robust nonlinear receding horizon control with constraint tightening: off line approximation and application to networked control system." Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3122.
Повний текст джерелаАнотація:
2007/2008Nonlinear Receding Horizon (RH) control, also known as moving horizon control or nonlinear Model Predictive Control (MPC), refers to a class of algorithms that make explicit use of a nonlinear process model to optimize the plant behavior, by computing a sequence of future ma- nipulated variable adjustments. Usually the optimal control sequence is obtained by minimizing a multi-stage cost functional on the basis of open-loop predictions. The presence of uncertainty in the model used for the optimization raises the question of robustness, i.e., the maintenance of certain properties such as stability and performance in the presence of uncertainty. The need for guaranteeing the closed-loop stability in presence of uncertainties motivates the conception of robust nonlinear MPC, in which the perturbations are explicitly taken in account in the design of the controller. When the nature of the uncertainty is know, and it is assumed to be bounded in some compact set, the robust RH control can be determined, in a natural way, by solving a min–max optimal control problem, that is, the performance objective is optimized for the worst-case scenario. However, the use of min-max techniques is limited by the high computational burden required to solve the optimization problem. In the case of constrained system, a possibility to ensure the robust constraint satisfaction and the closed-loop stability without resorting to min-max optimization consists in imposing restricted (tightened) constraints on the the predicted trajectories during the optimization. In this framework, an MPC scheme with constraint tightening for discrete-time nonlinear systems affected by state-dependent and norm bounded uncertainties is proposed and discussed. A novel method to tighten the constraints relying on the nominal state prediction is described, leading to less conservative set contractions than in the existing approaches. Moreover, by imposing a stabilizing state constraint at the end of the control horizon (in place of the usual terminal one placed at the end of the prediction horizon), less stringent assumptions can be posed on the terminal region, while improving the robust stability properties of the MPC closed-loop system. The robust nonlinear MPC formulation with tightened constraints is then used to design off- line approximate feedback laws able to guarantee the practical stability of the closed-loop system. By using off-line approximations, the computational burden due to the on-line optimization is removed, thus allowing for the application of the MPC to systems with fast dynamics. In this framework, we will also address the problem of approximating possibly discontinuous feedback functions, thus overcoming the limitation of existent approximation scheme which assume the continuity of the RH control law (whereas this condition is not always verified in practice, due to both nonlinearities and constraints). Finally, the problem of stabilizing constrained systems with networked unreliable (and de- layed) feedback and command channels is also considered. In order to satisfy the control ob- jectives for this class of systems, also referenced to as Networked Control Systems (NCS’s), a control scheme based on the combined use of constraint tightening MPC with a delay compen- sation strategy will be proposed and analyzed. The stability properties of all the aforementioned MPC schemes are characterized by using the regional Input-to-State Stability (ISS) tool. The ISS approach allows to analyze the depen- dence of state trajectories of nonlinear systems on the magnitude of inputs, which can represent control variables or disturbances. Typically, in MPC the ISS property is characterized in terms of Lyapunov functions, both for historical and practical reasons, since the optimal finite horizon cost of the optimization problem can be easily used for this task. Note that, in order to study the ISS property of MPC closed-loop systems, global results are in general not useful because, due to the presence of state and input constraints, it is impossible to establish global bounds for the multi-stage cost used as Lyapunov function. On the other hand local results do not allow to analyze the properties of the predictive control law in terms of its region of attraction. There- fore, regional ISS results have to employed for MPC controlled systems. Moreover, in the case of NCS, the resulting control strategy yields to a time-varying closed-loop system, whose stability properties can be analyzed using a novel regional ISS characterization in terms of time-varying Lyapunov functions.
XXI Ciclo
1980
29
Assalone, Andrea. "Kernel - based continous - time systems identification: methods and tools." Doctoral thesis, Università degli studi di Trieste, 2014. http://hdl.handle.net/10077/9990.
Повний текст джерелаАнотація:
2012/2013Questa tesi ha lo scopo di formalizzare un nuovo filone teorico, che deriva dall’algebra degli operatori lineari integrali di Fredholm-Volterra agenti su spazi di Hilbert, per la sintesi di stimatori dello stato e parametrici per sistemi dinamici a tempo continuo sfruttando le misure ingressi/uscite, soggetti a perturbazione tempo-varianti. In maniera da ottenere stime non-asintotiche di sistemi dinamici a tempo continuo, i metodi classici tipicamente aumentano la dimensione del vettore delle variabili di decisione con le condizioni iniziali incognite di stati non misurati. Tuttavia, questo porta ad un accrescimento della complessitá dell’algoritmo. Recentemente, diversi metodi di stima algebrici sono stati sviluppati, sfruttando un approccio algebrico piuttosto che da una prospettiva statistica o teorica. Mentre le forti fondamenta teoriche e le proprietá di convergenza non asintotiche rappresentano caratteristiche notevoli per questi metodi, il principale inconveniente é che l’implementazione pratica produce una dinamica internamente instabile. Quindi, la progettazione di metodi di stima per questi tipi di sistemi é un argomento importante ed emergente. L’obiettivo di questo lavoro é quello di presentare alcuni risultati recenti, considerando diversi aspetti e affrontando alcuni dei problemi che emergono quando si progettano algoritmi di identificazione. Lo scopo é sviluppare un’architettura di stima con proprietá di convergenza molto veloci e internamente stabile. Seguendo un ordine logico, prima di tutto verrá progettato l’algoritmo di identificazione proponendo una nuova architettura basata sui kernel, utilizzando l’algebra degli operatori lineari integrali di Fredholm-Volterra. Inoltre, la metodologia proposta sará affrontata in maniera da progettare stimatori per sistemi dinamici a tempo continuo con proprietá di convergenza molto veloci, caratterizzati da gradi relativi limitati e possibilmente affetti da perturbazioni strutturate. Piú nello specifico, il progetto di adeguati kernel di operatori lineari integrali non-anticipativi dará origine a stimatori caratterizzati da proprietá di convergenza idealmente "non- asintotiche".Le analisi delle proprietá dei kernel verrá affrontata e due classi di funzioni kernel ammissibili saranno introdotte: una per il problema di stima parametrica e uno per il problema di stima dello stato. Gli operatori che verranno indotti da tali funzioni kernel proposte, ammettono realizzazione spazio-stato implementabile (cioé a dimensione finita e internamente stabile). Allo scopo di dare maggior completezza, l’analisi del bias dello stimatore proposto verrá esaminata, derivando le proprietá asintotiche dell’algoritmo di identificazione e dimostrando che le funzioni kernel possono essere pro- gettate tenendo in debito conto i risultati ottenuti in questa analisi.
This thesis is aimed at the formalization of a new theoretical framework, arising from the algebra of Fredholm-Volterra linear integral operators acting on Hilbert spaces, for the synthesis of non-asymptotic state and parameter estimators for continuous-time dynamical systems from input-output measurements subject to time-varying perturbations. In order to achieve non-asymptotic estimates of continuous-time dynamical systems, classical methods usually augment the vector of decision variables with the unknown initial conditions of the non measured states. However, this comes at the price of an increase of complexity for the algorithm. Recently, several algebraic estimation methods have been developed, arising from an algebraic setting rather than from a statistical or a systems-theoretic perspective. While the strong theoretical foundations and the non-asymptotic convergence property represent oustanding features of these methods, the major drawback is that the practical implementation ends up with an internally unstable dynamic. Therefore, the design of estimation methods for these kind of systems is an important and emergent topic. The goal of this work is to present some recent results, considering different frameworks and facing some of the issues emerging when dealing with the design of identification algorithms. The target is to develop a comprehensive estimation architecture with fast convergence properties and internally stable. Following a logical order, first of all we design the identification algorithm by proposing a novel kernel-based architecture, by means of the algebra of Fredholm-Volterra linear integral operators. Besides, the proposed methodology is addressed in order to design estimators with very fast convergence properties for continuous-time dynamic systems characterized by bounded relative degree and possibly affected by structured perturbations. More specifically, the design of suitable kernels of non-anticipative linear integral operators gives rise to estimators characterized by convergence properties ideally “non-asymptotic". The analysis of the properties of the kernels guaranteeing such a fast convergence is addressed and two classes of admissible kernel functions are introduced: one for the parameter estimation problem and one for the state estimation problem. The operators induced by the proposed kernels admit implementable (i.e., finite-dimensional and internally stable) state- space realizations. For the sake of completeness, the bias analysis of the proposed estimator is addressed, deriving the asymptotic properties of the identification algorithm and demonstrating that the kernel functions can be designed taking in account the results obtained with this analysis.
XXVI Ciclo
1984
30
Toffoli, Valeria. "Superhydrophobic BIOMEMS sensor arrays: development of actuation and readout electronic strategies." Doctoral thesis, Università degli studi di Trieste, 2014. http://hdl.handle.net/10077/9993.
Повний текст джерелаАнотація:
2012/2013La tecnologia dei sistemi micro-elettro-meccanici (MEMS) ha dimostrato d’avere grandi potenzialità in molti campi, in particolare nei sistemi bio-medicali. Essa si basa infatti su processi di fabbricazione ad altro volume produttivo, permettendo una considerevole riduzione dei costi per dispositivo. Un ulteriore beneficio di questa tecnologia risiede nella possibilità di dimensionare i dispositivi fino a raggiungere l’ordine del submicron, così da consentire l’integrazione e il monitoraggio in tempo reale di sistemi sensibili a biomarker di tipo medicale e biologici. Tra gli obiettivi futuri dei MEMS biomedicali (BioMEMS) vi è la realizzazione di dispositivi in grado di interfacciarsi direttamente con il paziente e definirne lo stato di salute grazie alla rilevazione del livello di centinaia di diversi biomarker (siano essi chimici o fisici). La medicina assumerebbe in questa visione una configurazione ad personam nella quale al paziente verrebbe prontamente somministrato un quantitativo di medicinale adatto alle risposte del suo organismo. A tale scopo i dispositivi MEMS devono essere in grado di effettuare analisi multiple operando in un ambiente liquido. Tuttavia è proprio l’ambiente liquido a comportare la riduzione di sensibilità e, quindi, di performance dei sensori MEMS. La presente ricerca si pone lo scopo di sviluppare nuovi sistemi elettronici di misurazione e attuazione di due distinte tipologie di BioMEMS risonanti operanti in liquido, i cantilever e i pillar. In particolare verrano trattati tre argomenti: la realizzazione di setup ottici per applicazione dei MEMS in liquido ed in aria, la progettazione di sistemi elettronici di attuazione e lettura di singoli pillar nel loro comportamento in frequenza e lo sviluppo di un software LabVIEW in grado di programmare un FPGA ed ottenere un PLL digitale da impiegarsi nell’analisi in tempo reale del comportamento in frequenza di RF-MEMS. Il primo progetto è stato sviluppato in collaborazione l'Università di Kaiserslautern (Germania) e prevedeva la realizzazione di sistemi microfluidici e setups ottici, interfacciati in modo tale da permettere la rilevazione della risposta in frequenza di molteplici MEMS operanti in parallelo. Nel secondo progetto l’obiettivo era la realizzazione di un sistema elettronico in grado di integrare in un unico dispositivo i sistemi di attuazione e lettura dei pillar. In particolare siamo stati in grado di modulare l’ampiezza di risonanza dei nostri dispositivi risonanti mediante l’applicazione della forza di polarizzazione Kelvin mentre lo sviluppo del sistema di lettura richiede ulteriore lavoro di indagine. Infine, nell'ultimo progetto è stato realizzato un sistema PLL digitale con 10 MHz di banda passante utilizzando la tecnologia della National Instruments (FlexRIO NI5781R). Mediante questo PLL si è potuto identificare la frequenza di risonanza di diverse tipologie di MEMS e se ne è seguite le variazioni in tempo reale . Le attività di ricerca sperimentale sono state eseguite presso il laboratorio CNR- IOM a Trieste.
XXVI Ciclo
1985
31
Sarra, Fiore Angelo. "Complex Networks: Data Analysis, Models, Tools, Applications." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1073.
Повний текст джерелаАнотація:
We live, as defined by prof. Chua, in the age of complexity, whose ubiquity
is the reason of the increasing interest in the scientific community.
Many of the systems that surround us are complex. The goal of understanding their properties motivates many researchers.
Universal laws and phenomena are essential to inquiry and to understand and all scientific endeavor is based on the existence of universality, which manifests itself in diverse ways. The study of complex systems as a new effort seeks to increase the ability to understand the universality that arises when systems are highly complex.
A complex system may be thinked as a system formed out of many components whose behavior is emergent, meaning that the behavior of the system cannot be simply inferred from the behavior of its components.
In fact, it is not possible to describe the whole without describing each part, and each part must be described in relation to other parts to understand the behavior of a complex system.
The amount of information necessary to describe the behavior of such a system is a measure of its complexity.
Usually, the behavior of a complex system is investigated considering how the simple units communicate. Thus, a complex system can be defined by its network of interactions and studied according to graph theory.
The aim of this PhD Thesis is to provide new tools and strategies for the analysis and modeling of complex systems. The designed tools will be then applied to two particular classes of complex systems: complex networks and cellular automata.
In particular, several fundamental topics of complex networks have been faced in this work. Starting from the key issue of data analysis in networks, which due to the large availability of data has now become a fundamental aspect of the research in complex networks, we found that existing models do not adequately reproduce the characteristics, often uniques, of the social networks analysed and introduced a new model of growing network based on an attachment to communities instead of sparse nodes. We have then considered one of the major applications of complex networks, i.e., power grids. While most of the approaches existing in literature are static ones and focuse on the network topology, we considered a model which explicitely takes into account the oscillatory dynamics of power grid nodes. Our results revealed different qualitative scenarios to the network failure. Finally, the Thesis focuses on a hardware tool for the emulation of a nearest-neighbor coupled network, which, despite its simple topology, is able to generate many complex phenomena and for a set of parameters is equivalent to a Turing machine.
The Thesis is organized as follow: in Chapter 1 complex systems and in particular complex networks will be introduced; Chapter 2 and 3 will describe the results obtained on social networks and power grids; Chapter 4 will introduce a new stand-alone complex system hardware emulator; in the conclusive Chapter the conclusions will be drawn.
32
Di, Stefan Agnese Giuseppa Federica. "Next generation of numerical models for inferring the volcano dynamics from geophysical observations." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1074.
Повний текст джерелаАнотація:
We present a 3D numerical model based on FEM (Finite Element Method) to jointly evaluate geophysical changes caused by dislocation and overpressure sources in volcanic areas. A coupled numerical problem was solved to estimate ground deformation, gravity and magnetic changes produced by stress redistribution accompanying magma migration within the volcano edifice. We successfully applied the integrated numerical procedure to image the inflation process of 2005-2006 and the magmatic intrusion of the 2008 eruption. A hybrid approach for forward and inverse geophysical modeling, based on Artificial Neural Networks (ANN) and Finite Element Method (FEM), is proposed in order to properly identify the parameters of volcanic pressure sources from geophysical observations at ground surface. Our FEM-based approach improves the reliability of model-based assessments of geophysical observations that can prelude to an impending eruption.
33
Tomarchio, Salvatore Gaspare. "Power Switching Converters with very low power consumption and high efficiency for energy savings." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1311.
Повний текст джерелаАнотація:
The objective of this research is the analysis of power switching converters with targets of very low power consumption and high efficiency for being used in new system for energy savings.
Typically, they are implemented as Switching Mode Power Supply (SMPS) modules in different type of applications in both consumer and energy businesses .
In particular have been considered power supply systems with output power in the class of low and medium power, in the range from few watts up to hundreds watts.
Referring to consumer business, the main fields of application are lighting and home appliances where in the last years the international Agencies and Governments have been focused their attention to ask for reducing the continuous energy waste.
Therefore, more restricted and challenging constraints have been fixed in order to reduce the energy waste and to improve the level of performances of new products, that pushed the introduction of new technologies and new design solutions.
In particular in the lighting applications the improvement in LED technologies is leading to the development of LED lamps with higher light efficiency and lower power consumption.
The analysis will start making a overview of the principal topologies of switching converters used to drive the LED bulbs. Advantages and disadvantages will be shown for each topology. Then the flyback topology will be analyzed and discussed in more details, since it is considered the most promising one. Finally, an alternative schematic will be proposed in order to increase the electrical performance of the whole power conversion system.
On the other side in the home appliance applications there are conditions where the energy is consumed by the device when this does not work or does not perform its main functions and that happens without the final user realizing it. One condition is when the device is put in standby status.
For this case the analysis of the commonly used techniques for reducing power consumption in the switching converter is discussed and a new technique for reducing power during the inactivity state of the appliance system is proposed.
The proposed solution works on the feedback network, introducing a perturbation on the feedback signal: in this way the main power transistor, in the converter, is switched off and the output voltage of the converter is settled to zero. This solution allows an important reduction of the effective power consumption of the system.
In order to confirm this solution an auxiliary SMPS with output power of 5 W to supply the user interface of a washing machine has been designed, and the converter topology used is a Flyback converter, compliant with the current regulations of the home appliance applications.
In addition a prototype is realized and then simulations in PSpice, thermal and electrical measurements are performed in order to verify the operations of the converter in different environmental and electrical conditions.
Looking at the business of energy conversion, in the design of applications of high power systems an important issue is to provide low voltages, in the range of tens of Volt, tapping from high voltage input line, which is usually in the range between hundreds of Volt to kilovolt, by means of switching power supplies. Low voltages are needed to supply the logic control circuits and the power semiconductors driving the applications. The supply system has to deal, consequently, with both wide input voltage range and electrical insulation. The evaluation of the operative conditions of a driving system for IGCT devices, used in a transmission system application with wide input voltage range, is described. The design of a 100 W supply converter is shown considering all the issues related with the series connection of power devices and the needs of insulation.
Converter design, modelling and experimental results are shown together with the evaluation of the efficiency of the proposed solution.
34
Mangiameli, Michele. "Navigation systems for autonomous robots based on open source gis technologies." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1302.
Повний текст джерелаАнотація:
Man has always dreamed of building artificial beings, which take over tedious or dangerous tasks, with abilities of entertainment and subject to human commands. In everyday language, these artificial beings are called robots . Robots are characterized for the capability to act in the environment using a mechanical locomotion system and to interact with the objects present in the environment using a handling system , or a perceptive capacity to measure parameters relating to their internal state using proprioceptive sensors, and to measure external parameters, using exteroceptive sensors, and the capability to establish an intelligent link between perceptions and actions, using a control system that works taking into account the mechanical constraints of the robot with respect to those inside the environment.There are two fundamental aspects for mobile robotics: the estimation of the robot position in the operating environment and the robotic mapping to acquire spatial models of the physical environment.This aspect is very serious when the operating environment of the robot is unknown. The mapping problem is generally considered as one of the most important challenges in the pursuit of building truly autonomous mobile robots, because it requires the integration of information gathered by the robots sensors into a given representation. So the two central aspects in mapping are the representation of the environment and the interpretation of sensor data. To acquire a map and to estimate its position, a robot should be equipped with sensors that enable it to perceive the outside world. Common sensors usable for this task include cameras, range finders using sonar, laser, and infrared technologies, radar, tactile sensors, compasses, laser scanner and GPS for outdoor applications.The navigation of a robot in an environment for reaching a goal requires the solution of three tasks: mapping, localization, and path planning. In this PhD thesis is the management of the navigation for autonomous mobile robots in outdoor environments using geographic information systems. This technology can be seen as an extension of classical topography but uses advanced functionality for the management of any type of information as a reference spatial and temporal in software environment.The GIS environment has a layered architecture where the raster layer represents the cartographic base georeferenced with topographic algorithms. On the raster base, different vector layers are overlapped as sets of geometric primitives (points, lines, areas, surfaces and volumes) for the representation of real-world phenomena.
For this reason, the core of this PhD thesis is the development of a navigation system for autonomous robots based on the GIS technology using cartography and maps geo-referenced with the rigorous approach of geomatics to analyze the satellite positioning data detected by the robot and to manage its navigation accurately. In particular the thesis exploited desktop GIS platforms and developed webGis platforms using free and open source software for optimizing and customizing these platforms. For managing the navigation of the robot and the spatial data, an external spatial DBMS (DataBase Management System) was also developed with free and open source technologies.This PhD thesis aims at developing a navigation system for autonomous robots based on the GIS technology using cartography and maps geo-referenced with the rigorous approach of geomatics to analyze the satellite positioning data detected by the robot and to manage its navigation accurately. In particular, the thesis exploits desktop GIS platforms and develops webGis platforms using free and open source software for optimizing and customizing these platforms. For managing the navigation of the robot and the spatial data, an external spatial DBMS (DataBase Management System) has been also developed with free and open source technologies.
35
De, Leo Elena. "Introducing communication and networking technologies into lab-on-chip systems." Doctoral thesis, Università di Catania, 2014. http://hdl.handle.net/10761/1494.
Повний текст джерелаАнотація:
Microfluidics is a science and a technology which deals with manipulation and control of small volumes of fluids flowing in channels of micro-scale size. It is currently used for Labs-On-a-Chip (LoCs) applications mainly. In this context, recently fluids have been used in the discrete form of droplets or bubbles dispersed into another immiscible fluid. In this case, droplets or bubbles can be exploited as a means to transport digital information between microfluidic components, with sequences of particles (i.e. droplets or bubbles) representing sequences of binary values.
LoCs are today realized through monolithic devices in which samples are processed by passing them through a predetermined sequence of elements connected by fixed and preconfigured microfluidic channels. To increase reusability of LoCs, effectiveness and flexibility, networking functionalities can be introduced so that the sequence of elements involved in the processing can be dynamically selected.
Accordingly, in this thesis we introduce the Networked LoC (NLoC) paradigm that brings networking concepts and solutions in microfluidic systems such as LoCs. More specifically, in this paper the need for the introduction of the NLoC paradigm is motivated, its required functions are identified, a system architecture is proposed, and the related physical level design aspects, such as channel characterization, information representation and information capacity are investigated; finally a switching device is proposed and studied.
36
Chiarello, Viviana. "Analisys and Syntesys of Thin-Film Solar Cells with Metallic Nanoparticles." Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/3803.
Повний текст джерелаАнотація:
In this thesis it is shown that the FEM-RBCI method can be successfully applied to the analysis of the scattering of time-harmonic electromagnetic waves at optical frequencies from metallic nanoparticles of arbitrary shape.
Moreover, the optimization of a thin solar cell with metallic nanoparticles is performed by means of Genetic Algorithms and the Finite Element Method. The goal is to design a solar cell which shows good performances in terms of sunlight absorption. Suitable Genetic Algorithms with varying crossover and mutation probabilities are employed. The optimum is reached in about half the time required by the standard procedure. The optimized solar cell performs well in the sunlight frequency bandwidth.
37
La, Delfa Gaetano Carmelo. "Methodologies and Technologies for Indoor Localization: a Computer Vision Based Approach." Doctoral thesis, Università di Catania, 2016. http://hdl.handle.net/10761/3928.
Повний текст джерелаАнотація:
The massive diffusion of smartphones we are seeing in the last years, the growing interest for everything related to wearable devices and Internet of Things (IoT), the exponential rise of Location Based Services (LBS: services based on the position of the users and accessible through the device) has meant that technologies capable of determining the position of the user inside a specific context have taken a crucial role in the consumer sector. In outdoor environments, GPS (Global Positioning System) can be considered today as a standard de facto , while the localization and navigation in indoor environments still remains one of the technological challenges of the next years.
Indoor Positioning Systems (IPS) have a remarkable importance in a lot of important market segments such as the retail sectors for con- textual advertising (commercial centers, supermarkets), touristic and transportation sectors (airports, museums), healthcare sectors (hospitals). Sometimes, in emergency situations they can make the difference between life and death. Even if actually doesn t exist a definitive solution as efficient and precise as GPS and with all its advantages, various approaches and methodologies has been proposed in the last years in scientific literature, and several technologies are appearing into the market. The researches have focused, rather than on realizing a general purpose IPS with high performances everywhere, on the development of a variety of solutions suitable for the specific place of deployment and which meet the specifics precision, security, invasiveness and cost requirements.
In the first part of this doctoral dissertation, after an overview on the main methodologies used for locating a user in an indoor environment, we will analyze the state of the art and present some of the most interesting cases. We will focus particularly on approaches which utilize the smartphone s inertial sensors and 2D visual markers based computer vision techniques. In the second part of the dissertation we will propose our own solution to the indoor localization problem. Such solution consists in a visual markers system deployed onto the area of interest s floor and a step detection algorithm. We will compare the performances of three types of markers, taken from the scientific literature, from the point of view of the specifications required by the suggested solution, and choose the most better performing one. We will then propose a client - server architecture for managing the whole process of tracking the user inside a building, and present an implementation of the client, on the iOS platform. Finally in the last part of the dissertation, we will show the obtained results, and talk about the possible future works.
38
Nunnari, Silvia. "Modeling solar radiation and wind speed time series for renewable energy applications." Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/3978.
Повний текст джерелаАнотація:
The problem of predicting weather variables, such as solar radiation and wind speed, is of great interest for integrating renewable energies plants, into the electric grid. Indeed, since renewable energy sources are intermittent in nature, predicting future values is important to allow the grid to dispatching generators, in order to satisfy the demand. There are essentially two ways to address the issue of weather variables prediction. One is by using Numerical Weather Forecasting (NWF) models, which are reliable, but also quite complex and requires real time information, usually available from Meteorological Agencies only. Furthermore, very powerful computers are required to solve the differential equations involved. The other kinds of methods are represented by the so-called statistical modeling approaches, which are based on the use of past data recorded at the site of interest. These latter kinds of methods, compared to the former ones, require less computational efforts, but are appropriate only for short time horizons. This PhD Thesis was devoted to study short-term prediction models for solar radiation and wind speed time series and assessing their performance in the range [1, 24] hours. It was also studied the predictability of the daily average values, which for obvious reasons, is much more difficult than that of predicting the hourly averages. To mitigate, as far as possible, the difficulties, the prediction was reformulated in terms of a classification problem. In such a way, instead of predicting 1-day ahead the average value, the target was to predict the class. In this framework, of course, the prediction is as far difficult as large is the number of considered classes. Thus accuracy of 1-day ahead prediction models of the wind speed class was studied, for various frameworks.
39
Pedroncelli, Giovanni. "Distributed Discrete Consensus Algorithms: Theory and Applications for the Task Assignment Problem." Doctoral thesis, Università degli studi di Trieste, 2015. http://hdl.handle.net/10077/10975.
Повний текст джерелаАнотація:
2013/2014Distributed computation paradigms belong to a research field of increasing interest. Using these algorithms will allow to exploit the capabilities of large scale networks and systems in the near future. Relevant information for the resolution of a problem are distributed among a network of agents with limited memory and computation capability; the problem is solved only by means of local computation and message exchange between neighbour agents. In this thesis we consider the multi-agent assignment problem dealt with distributed computation: a network of agents has to cooperatively negotiate the assignment of a number of tasks by applying a distributed discrete consensus algorithm which defines how the agents exchange information. Consensus algorithms are dealt with always more frequently in the related scientific literature. Therefore, in the first chapter of this thesis we present a related literature review containing some of the most interesting works concerning distributed computation and, in particular, distributed consensus algorithms: some of these works deal with the theory of consensus algorithms, in particular convergence properties, others deal with applications of these algorithms. In the second chapter the main contribution of this thesis is presented: aniterative distributed discrete consensus algorithm based on the resolution of local linear integer optimization problems (L-ILPs) to be used for the multi-agent assignment problem. The algorithm is characterized by theorems proving convergence to a final solution and the value of the convergence time expressed in terms of number of iterations. The chapter is concluded by a performance analysis by means of the results of simulations performed with Matlab software. All the results are presented considering two different network topologies in order to model two different real life scenarios for the connection among agents. The third chapter presents an interesting application of the proposed algorithm: a network of charging stations (considered as agents) has to reach a consensus on the assignment of a number of Electric Vehicles (EVs) requiring to be recharged. In this application the algorithm proposed in the previous chapter undergoes several modifications in order to model effectively this case: considering the inter-arrival times of vehicles to a charging station, a non-linear element appears in the objective function and therefore a novel algorithm to be performed before the assignment algorithm is presented; this algorithm defines the order in which the assigned vehicles have to reach a charging station. Moreover, a communication protocol is proposed by which charging stations and vehicles can communicate and exchange information also allowing charging stations to send to each assigned vehicle the maximum waiting time which can pass before a vehicle loses its right to be recharged. The chapter ends with an example of application of the rivisited assignment algorithm. In the fourth and last chapter, we present an application in an industrial environment: a network of Autonomous Guided Vehicles (AGVs) in a warehouse modeled as a graph has to perform the distributed discrete consensus algorithm in order to assign themselves a set of destinations in which some tasks are located. This application deals not only with the task assignment problem but also with the following destination reaching problem: therefore a distributed coordination algorithm is proposed which allows the AGVs to move into the warehouse avoiding collisions and deadlock. An example of the control strategy application involving both the assignment and coordination algorithms concludes this chapter.
XXVII Ciclo
1986
40
Basile, Graziano. "Analisi teorico sperimentale di materiali iperelastici." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1108.
Повний текст джерелаАнотація:
Il presente lavoro è incentrato sulla caratterizzazione di materiali a comportamento Iperelastico, e quindi volto alla determinazione dei parametri della funzione energia di deformazione.
Per la realizzazione delle prove meccaniche, sono stati progettati e realizzati i sistemi di test di tipo planare, utilizzati anche per prove monoassiali, e di un opportuno sistema per test biassiali.
I sistemi permettono in maniera agevole la realizzazione dei test necessari e passare in maniera veloce da un set-up ad un altro.
Per l impossibilità di poter applicare le tecniche di estensimetria di contatto, per via delle grandi deformazioni in gioco, è presentata una metodologia di rilievo mediante l utilizzo di una camera CCD ad alta risoluzione ed una procedura automatica di post elaborazione e sincronizzazione dei dati provenienti dalla prova mediante l utilizzo dei software Labview® e Matlab®.
Il sistema misuristico messo a punto ha dato ottimi risultati e la perfetta sovrapposizione delle curve sforzo-deformazione ottenute con le curve provenienti dalla macchina di prova, nel caso di prove monoassiali e planari, mostrando la bontà della procedura e l applicabilità sui test biassiali dove non è possibile effettuare un confronto diretto con i dati provenienti dalla macchina monoassiale.
Il materiale utilizzato al raggiungimento dello scopo è un silicone commerciale, prodotto dalla Angst + Pfister, con sigla VMQ.
Infine, ottenute le curve caratteristiche, quindi caratterizzato il materiale secondo il miglior fit con i modelli disponibili in letteratura, è stata verificata la rispondenza del modello con l analisi numerica agli elementi finiti.
È stato anche proposto un metodo iterativo basato sull analisi dell immagine e analisi numeriche agli elementi finiti per l identificazione della componente volumetrica.
Concludendo, il presente lavoro non ha avuto come unico obiettivo quello di testare un materiale a comportamento non lineare, ma anche quello di realizzare in maniera semplice ed accessibile una metodologia di test soprattutto nel caso bi-assiale e nel contempo capire e darne il giusto peso al termine volumetrico nei modelli di energia di deformazione.
41
Pagano, Francesco. "Smart Systems Based on Electroactive Polymers." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1307.
Повний текст джерелаАнотація:
The purpose of this thesis is the development and analysis of smart systems based on electroactive polymers (EAPs). Thanks to their sensing and actuation capabilities, devices based on EAPs, like ionic polymer metal composites (IPMCs), realized by using a noble metal or ionic polymer polymer composites (IP2Cs), where a conducting polymer replaces the metal, pave the road to the development of new integrated devices , being the conditioning circuitry very simple, that could be of high interest in fields such as engineering, biomechanics, aerospace, and robotics.
Furthermore, in the near future the entire system, included the conditioning circuitry, could be realized by using plastic based electronics, opening new possibilities for a post-silicon era.
Characteristics like the large deformations obtained under the ef-fect of a low level applied voltage signal, the capability to transform a mechanical stimulus into a detectable electrical signal and the vibra-tional characteristics of a cantilever beam, have contributed to selecting the IPMC as candidates for the research carried out.
The idea that drove this thesis is to proof the possibility to use EAPs to realize a smart systems that can both perform measurements in harsh environments while being energetically self-sufficient.
This has prompted the design, the realization and the test of sen-sors, such as a seismic sensor and a viscometer, and of a device able to harvest energy from ambient vibrations.
This work has allowed to assert that, although the technology used is still room for improvement, this idea is feasible.
42
Cappadonna, Fulvio Antonio. "Application of exact and approximate optimization methods to novel scheduling problems." Doctoral thesis, Università di Catania, 2014. http://hdl.handle.net/10761/1482.
Повний текст джерелаАнотація:
The application of exact and heuristic optimization techniques to scheduling problems pertaining to production processes has been widely investigated over the last decades by the relevant scientific literature in the field of industrial systems design and analysis. In general, the term scheduling is used with reference to the allocation of resources to tasks over time, so to execute all planned activities according to a given performance objective (minimization of costs, minimization of production time, due dates fulfilment, etc.). Even though basic scheduling problems have been effectively solved long time ago, this topic still remains attractive for expert and practitioners, as the technological innovation of production processes and the need for effective planning activities emerging from new sectors still set new frontiers to the scheduling optimization research.
The aim of the present Thesis is to investigate three scheduling problems that have not been addressed yet by the literature, even though they have a clear correspondence to real-world manufacturing environments.
The first problem addressed is the minimization of makespan in an unrelated parallel machine system with sequence-dependent setup times and limited human resources. Workers are needed to perform setup operations before each job is processed; they are supposed to be a critical resource as their number is assumed to be lower than the number of workstations available in the production shop. In addition, each worker is characterized by a provided skill level, which affects the time required for completing setup operations. Firstly, a Mixed Integer Linear Programming (MILP) model suitable for tackling small instances of the problem in hand is illustrated. Then, an optimization framework based on Genetic Algorithms (GAs) is presented with the aim of effectively addressing larger test cases. Three different procedures are proposed, namely a permutation based GA, a multi-encoding GA, and a hybrid GA. An extensive benchmark including both small-and large-sized instances is taken as reference for both calibration and comparison of the proposed methods, which have been performed by means of ANOVA analysis.
The second problem addressed is the minimization of makespan in a Flow Shop Sequence Dependent Group Scheduling (FSDGS) problem entailing the worker allocation issue. As first, a Mixed Integer Linear Programming (MILP) formulation for the problem is given. Then, a well-known benchmark arisen from literature is adopted for carrying out an extensive comparison campaign among three specifically developed metaheuristic methods based on a GA framework. Afterwards, the best procedure among those tested is compared with a well-performing algorithm recently proposed in the field of FSDGS problems.
The third problem addressed is the minimization of makespan in a hybrid flow shop inspired to a truly observed micro-electronics manufacturing environment, is illustrated. Overlap between jobs, waiting time limit of jobs within inter-stage buffers as well as machine unavailability time intervals represent just a part of the constraints which characterize the problem here investigated. A MILP model of the problem has been developed with the aim to validate the performance concerning the proposed optimization technique, based on a two-phase metaheuristics (MEs). In the first phase the proposed ME algorithm evolves similarly to a genetic algorithm equipped with a regular permutation encoding. Subsequently, a random search algorithm equipped with an m-stage permutation encoding is launched for improving the algorithm strength in terms of both exploration and exploitation. Extensive numerical studies on a benchmark of problems, along with a properly arranged ANOVA analysis, demonstrate the statistical outperformance of the proposed approach with respect to the traditional optimization approach based on a single encoding.
43
Leonardi, Ornella. "Circularly polarized antennas." Doctoral thesis, Università di Catania, 2014. http://hdl.handle.net/10761/1496.
Повний текст джерелаАнотація:
In recent years low profile, lightness, compactness, easy manufacturing
and integrability with solid-state devices on a circuit board have become a
priority in the antenna design. Microstrip antennas are a possible answer
to these new requirements in several areas, such as remote sensing, mobile satellite and cellular communications, direct broadcast satellite (DBS)
system and global positioning system (GPS).
Many of the above mentioned applications make use of circularly polarized
antennas. However, such requirement in planar microstrip antenna
is not a trivial task since many factors have to be considered including
fabrication tolerance and systematic errors in the manufacturing process.
In the present thesis we address the task to achieve circular polarization
with very compact planar antennas in two ways:
1) a more conventional one dealing with two innovative designs;
2) a less conventional one through of artificial materials, such as High
Impedance Surface (HIS).
As far as the first point is concerned, two standard designs have been
developed for a Dedicated Short Range Communication (DSRC) system.
In particular, we have proposed two innovative compact antennas that
represent a step forward with respect to other available DSRC solution.
The two proposed antenna prototypes have been optimized, fabricated
and experimentally tested. They represent an answer to the need of
achieving good circular polarization antennas in a small mobile On-Board
Unit (OBU) of a DSRC system.
As a further study, we have considered to improve performance such
as the radiated power, the gain and the directivity, or to reduce the global
antenna thickness. For this reason we have developed a full-wave model
for periodic surface and considered their employment to achieve circular
polarization. As a proof of concept, we have tested a simple arrangement
that allows circular polarization of the radiated field.
The thesis is organized as follows.
In the first part, we briefly introduce some relevant technical features
of microstrip antenna s. Then the properties of circular polarized waves
are discussed, with particular interest in wireless communications. The
circular polarization quality factors and antenna measurement setup are
briefly introduced and discussed.
In the second part, we address the design and the experimental characterization of two circularly polarized microstrip patch antenna prototypes.
In the last part of the thesis, High Impedance Surfaces (HIS) are
briefly introduced. Then, a simple FEM-model is presented and compared
with the standard FTDT-model used in literature. In this respect,
a rectangular-array-patch working as HIS surface is considered and tested
to achieve circular polarization with a printed dipole.
44
Castorina, Giovanni. "Microwave accelerating structures: an innovative parallel coupled electron LINAC." Doctoral thesis, Università di Catania, 2018. http://hdl.handle.net/10761/3791.
Повний текст джерелаАнотація:
Particle accelerators are employed in many fields of the physics, engineering and medicine science. Although the idea of acceleration of charged particles by means of time varying electromagnetic field is an almost century old, the research and development in this field is active more than ever. An efficient particle accelerator gives the opportunity to reach energy levels not yet achieved and allows the study of the deepest laws of the physics. Also a better performance of the particle accelerators is desirable in order to develop compact table-top machine for medical or industrial purpose. The work here presented takes place in this framework. A parallel coupled electron LINAC has been studied for high gradient operation in the X-band frequency. This kind of device can address some issues of high gradient accelerating LINAC. Due to decoupled propagation axes for RF power and beam it is possible to increase the structure shunt impedance without affecting the cell to cell coupling, combining the advantages of travelling and standing wave structures. Besides in case of a breakdown only the energy stored in one cell is involved in the discharge process and not the total energy stored of the section, thus the damages caused by the breakdown event are expected to be smaller. Following a discussion on how the proposed configuration was conceived, full wave simulations were carried out to numerically validate the idea and to optimize the single cell in order to minimize the probability of breakdowns. After a successful cold simulation a beam dynamics analysis has been done in order to estimate the properties of the beam moving inside the device. Due to the small irises dimension the transverse wakefield can be source of instability for the bunch propagation. Therefore this issue has been investigated by means of numerical methods. Finally, the problem of the beam alignment with respect to the accelerating section is addressed and the results of a device suitable to beam position measurement are presented.
45
Donvito, Lidia. "A Microfluidic Communication Network For Programmable Passive Droplet-Based Devices: Design, Modeling and Analysis." Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/3855.
Повний текст джерелаАнотація:
I dispositivi microfluidici costituiscono una rivoluzione nella manipolazione di piccole quantità di fluidi, anche inferiori al picolitro. Le gocce in questi dispositivi fungono da microreattori, poiché sono utilizzate per incapsulare campioni e reagenti. Esse vengono manipolate all'interno del dispositivo per eseguire, su un chip con area nell'ordine dei centimetri, esperimenti normalmente realizzabili solo in laboratorio. L'obiettivo di questa tesi è estendere le funzionalità attuali dei dispositivi microfluidici passivi che manipolano gocce. Questi dispositivi non richiedono l'integrazione di componenti elettronici sul chip microfluidico né strumentazione di controllo per manipolare le gocce in maniera attiva. Essi, piuttosto, sfruttano soltanto effetti idrodinamici e, quindi, non richiedono un processo di fabbricazione complesso e costoso essendo totalmente passivi. I dispositivi microfluidici passivi che manipolano gocce sono usati principalmente per esperimenti e analisi chimiche e biologiche ma non sono in grado di eseguire protocolli di analisi complessi. Infatti, ogni dispositivo è progettato unicamente per una specifica applicazione ed è in grado di compiere solo operazioni semplici sulle gocce. Queste limitazioni possono essere superate introducendo una tecnologia di networking flessibile e modulare, che doti questi sistemi di una rete di comunicazione in modo da consentire sia lo scambio di informazione che di specie chimiche, trasportate entrambe dalle gocce. La rete microfluidica risultante sarà in grado di combinare le funzionalità specifiche di ciascun dispositivo microfluidico connesso ad essa, formando una potente e versatile piattaforma microfluidica in grado di implementare protocolli biochimici diversi su un unico chip.
46
Famoso, Carlo. "Vibrational Control of Large Scale Electromechanical Systems." Doctoral thesis, Università di Catania, 2015. http://hdl.handle.net/10761/3860.
Повний текст джерелаАнотація:
In this thesis, our attention focuses on the fundamental role of broad-spectrum mechanical vibrations [1] to favor the working of complex electromechanical systems.
Uncertainty has been already proved to allow self-organization in array of non-linear oscillator (pendulums, in particular) [2, 3]. The idea of our thesis is to show that also passive and active mechanical vibrations can play a key role on self-organization in a class of complex electromechanical systems.
In fact, large-scale electromechanical systems considered in this work is referred to as imperfect uncertain systems for which classical feedback control design cannot be suitably implemented.
For imperfect and uncertain systems, we mean systems including also unmodeled dynamics, intermittently arising, and uncertain parameters.
In order to control arrays of such types of systems, made by coupling a large number of linear low order units, it is not convenient to consider classical control approach [4].
The strategy to control each unit with a local feedback loops, indeed, is not practical as it leads to numerous and different control actions.
On the contrary, the idea of our research is to use only few control actions, in order to control the whole system, by exploiting its intrinsic properties of self-organization stimulated by the control actions.
This work is organized as follows.
Chapter I is about the new class of systems that are experimentally realized. Some qualitative exploration about them has been also given with reference to the control task.
In the Chapter II the problem is introduced by focusing on the key points of the research and the peculiar aspects of the structures showing some introductive experimental results.
In the Chapter III the mathematical framework of the general class of imperfect uncertain systems and the control feedback scheme are discussed.
In the Chapter IV the models of specific investigated large scale electromechanical systems are illustrated.
In the Chapter V the experimental results related to specific structures are discussed and compared with the numerical results obtained by simulations of the mathematical model.
Chapter VI includes the conclusive remarks and outlines the future perspective trends towards which this research could lead.
47
Scroppo, Marco Stefano. "Enhancing interoperability in industry 4.0." Doctoral thesis, Università di Catania, 2019. http://hdl.handle.net/10761/4151.
Повний текст джерелаАнотація:
The research objectives of this thesis consists in the definition of innovative proposal to enhance interoperability in Industry 4.0, IIoT and IoT. The research was focused on the interoperability between communication protocols, due to the knowledge that adoption of communication standards are of paramount importance in Industry 4.0, IIoT and IoT. Furthermore, no one communication standard is globally accepted as reference standard in these contexts. Nevertheless, among the various standard taken in consideration in literature, OPC UA international standard (IEC 62541) seems to be one of the leading candidates to become a reference standard. As for example, "Reference Architecture Model for Industrie 4.0" (RAMI 4.0) indicates for OPC UA the role to standardise machine-to-machine communication. Another example is the "Industrial Internet Reference Architecture" (IIRA), defined by the Industrial Internet Consortium (IIC), where OPC UA plays a strategic role as it is one of the core connectivity standards.
For this reason, the research has investigated the enhancement of interoperability in Industry 4.0, IoT and IIoT through improvements based on OPC UA.
First of all, the research was focused on the realisation of a proposal enabling the interoperability between OPC UA and generic users not compliant with OPC UA standard; in particular, it has been assumed to propose a way to allow the interaction between OPC UA and devices or applications using web technologies and without any knowledge of the standard. The realization of this integration has been achieved through the definition of a novel data model mapping the OPC UA Information Model, based on common web data-formats (e.g. JSON). This proposal has been called Integration between OPC UA and the Web .
After that, the research focus has been enlarged to propose a solution enabling the interoperability between OPC UA and IoT/IIoT ecosystems. Among the current IoT/IIoT ecosystems, OCF has been chosen for the integration with OPC UA, as it seems a promising solution to standardise the exchange of information into IoT as explained before. The solution mainly aims to realise a mapping between OPC UA and OCF information models and has been called Integration between OPC UA and OCF . Through this mapping, information maintained by an OPC UA Server may be used to populate a device compliant to OCF specifications which acts as a server, allowing it to expose this information to whatever client device in the OCF ecosystem. Vice versa, information maintained by an OCF Device may be published by an OPC UA Server allowing to make this information available to whatever OPC UA-compliant device.
48
Beltrame, Marco. "03-DPACS: an open source solution for critical PACS systems integratedin the 03 Consortium project." Doctoral thesis, Università degli studi di Trieste, 2008. http://hdl.handle.net/10077/2584.
Повний текст джерелаАнотація:
2006/2007ABSTRACT The student started his work towards the PhD. in 2005, joining the Bioengineering and ICT group of the University of Trieste, whose core research was in the e-health area. The personal research project conducted by the PhD student was inserted in the O3 Consortium research project, which had the aim to propose a complete solution for the adoption of open technology in the healthcare environment. The solution should become a whole new model for e-health application and include new products integrated with a development, support and business model. The PhD student contributed to the project in thinking and designing all the aspects of the complete solution presented in this thesis, in the development and business models, as well as in developing the products and in writing and publishing the results of the steps of this work. He personally contributed proposing the original idea of the support model and designing and implementing a product to test the proposed model. The student had an intermediate step in his personal project: he built a state of the art server for the management of DICOM data and of imaging objects (PACS – Picture and Archiving Communication System), with the aim to ease the adoption of e-health technology and to develop a product on which the model would have been tested. The research was conducted in the following way: first, based on the analysis of real world needs, literature and past experience, the definition of the O3 Consortium project software design guidelines (called “requirements” in the thesis) was performed. Then the product was designed and a new release of the PACS system was developed, implementing original solutions to best achieve all those “requirements”. The technological choices and the original aspects against the state of the art have been discussed and underlined throughout the entire thesis, such as the compliance to all the requirements and the choices for portability, project organization, standard implementation and performance. The idea of O3-DPACS being an integrated project, system plus support model has been also presented and discussed in the thesis.. It should be remarked again that the O3 Consortium means not only software development but also new procedures in both technology and service delivering. Moreover, the PhD student performed the validation of the software and the model, which needed to verify the assumption and to obtain the first results in the O3 Consortium research on e-health adoption. Should be noted the originality of the O3 Consortium project proposal of a whole complete application model to the healthcare real world based on open source software. No other solution for open source software application makes a complete proposal for all the topics of development, design, software architecture, support and business opportunity. Thus, a real research interest exists in testing and validating the model.
ABSTRACT Il dottorato comincia il suo corso di studi nel 2005, unendosi al gruppo di Bioengineering and ICT dell’Università di Trieste. Il principale filone di ricerca del gruppo è nell’area dell’e-health. Il progetto di ricerca condotto personalmente dal dottorando s’inserisce nel progetto O3-Consortium, che ha come obiettivo la realizzazione di una soluzione completa per l’adozione e la diffusione dell’e-health in sanità. Tale soluzione ha l’ambizione di diventare un nuovo modello di riferimento per l’utilizzo di tecnologie aperte in sanità, e per l’adozione di nuove tecnologie software in generale, includendo un insieme di prodotti all’avanguardia con nuovi modelli di sviluppo, produzione e assistenza. Il dottorando ha contribuito al lavoro di gruppo che ha portato all’ideazione e definizione di tutti gli aspetti della soluzione completa, contribuendo ai modelli di sviluppo, economici, alla realizzazione dei prodotti e alla scrittura del progetto stesso. Personalmente, ha contribuito proponendo l’idea originale del modello di assistenza, e progettando e sviluppando le parti più importanti del software scelto per la sperimentazione dei modelli. Il dottorando, come step intermedio, si è posto l’obiettivo di progettare un server all’avanguardia per l’archiviazione di dati e immagini cliniche (PACS), con lo scopo di testare e validare le idee e i principi definiti durante la creazione dei modelli. La ricerca è stata condotta in due passi. Inizialmente, sono state definite delle linee guida per la progettazione del software, chiamate “requirements” o requisiti, sia attraverso l’analisi dei bisogni reali che l’analisi della letteratura e dell’esperienza più che decennale del gruppo. Il secondo passo è stato concretizzare nel prodotto PACS la massima aderenza ai requisiti, progettando e realizzando l’archivio. Le scelte tecnologiche, i motivi e gli aspetti originali rispetto allo stato dell’arte, quali i metodi e il livello di soddisfacimento dei requisiti, le soluzioni per la portabilità del software, l’organizzazione del progetto software e le scelte in fatto di standard e performance, verranno discussi ed evidenziati sottodiversi aspetti nella tesi. Analogamente, verrà spiegato ed evidenziato il concetto che definisce O3-DPACS come progetto integrato, ove il prodotto è inscindibile da una politica adeguata di supporto. Occorre, infatti, rilevare che il progetto O3 Consortium non significa meramente produrre software, anche se con caratteristiche originali, quanto associarvi nuove procedure nella fornitura, gestione, manutenzione e supporto delle tecnologie software. Infine, il dottorando ha condotto a conclusione la sperimentazione e validazione del modello O3 applicato al proprio sistema PACS, ottenendo i primi risultati positivi nella ricerca delle migliori soluzioni per l’adozione dell’e-health all’interno del progetto O3 Consortium. A conclusione, va osservato che la peculiarità propria di O3 Consortium di voler proporre una soluzione completa per l’applicazione delle tecnologie aperte in sanità non ha analoghi, poiché alcuna altra proposta copre allo stesso tempo tutti gli aspetti quali lo sviluppo, l’assistenza, la ricerca, la fornitura del servizio. Ne consegue che esiste un reale interesse di ricerca nello sperimentare il modello O3.
XX Ciclo
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49
Beninato, Angela. "Development of innovative transducers based on Magnetic Fluids." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1077.
Повний текст джерелаАнотація:
It is quite common, in the advances on scientific research, to witness how material properties are exploited toward sensing applications in order to realize novel devices with high performances and tunable characteristics.
The synthesis of materials that are not in nature but that are rea-lized in chemical laboratories is often a response to such a requirement.
In particular meta materials and, in general, those materials made by the aggregation of several components to result into a multi-phase compound, are often very flexible and can provide very interesting performance in many different application fields.
Among these, magnetic materials have gained great relevance thanks to the possibility of controlling many of their features via external magnetic fields but also to the fact that their presence, position or space distribution, is easily detectable by using magnetic sensors.
In this Thesis an innovative approach to the development of com-plex devices made by multiple sensing parts together with actuators, and an integrated micro-fluidic system are considered.
The basic concept here is the use of new materials, called ferrofluids or magnetic fluids, made by a suspension of magnetic nanoparticles in a carrier fluid; several different devices have been developed and are shown here in order to demonstrate the possibility to use ferrofluids as a core material to realize both the actuating section of a fluidic system and the sensing.
The devices realized have been developed as laboratory prototypes and as proofs of concept of the ideas that have been first conceived, and then mathematical and numerical modeled prior to be designed as experimental devices.
Due to the intrinsic magnetic nature of the ferrofluids, a briefly introduction on basic concepts about magnetism is discussed in Chapter 1. A classification of materials in nature according to their magnetic behavior is reported, together with some details about the two fundamental source of magnetism: permanent magnets and electromagnets. Finally the main typologies of magnetic sensors commercially available are discussed.
In Chapter 2 the magnetic fluids are presented, together with their applications both in the market and in the research world. The main forces acting on a ferrofluid mass are discussed and modeled.
In Chapter 3 the attention is focused toward sensors realized during this Ph.D. research activity: a gyroscope, a displace-ment/acceleration sensor, a flow sensor and an inclinometer are dis-cussed, together with their physical model and with the experimental characterization.
In Chapter 4 research results on ferrofluids when used in actuators are presented. Plungers, valves and a position control system for ferrofluids drop in water have been developed. Two devices are presented: a pump in which a ferrofluid mass is controlled by an array of electromagnets, and a path tracking system, in which a mass is moved along a pre-defined path by a matrix of electromagnets.
The implementation toward integrated device is nowadays of paramount importance in the development of novel systems and transducers. The devices presented here has been developed as laboratory prototype and their scaling toward microsystems is straightforward and has been also addressed during this Ph.D. activity. In Chapter 5 two examples of integrated system in which ferrofluids can be used both in the fluidic part and in the sensing devices are presented. The former structure is a system that can be used for biological measures; in this case ferrofluid is used both in the fluidic part implementing valves and plunger, and as magnetic label for biological entities. The latter one represents a multi-sensorial systems, in which ferrofluids are used in order to implement valves and also as inertial mass of the sensors integrated in the structure.
50
Passarello, Giuseppe. "Programmazione di breve termine di impianti industriali di cogenerazione per la massimazione dei ricavi." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1100.
Повний текст джерелаАнотація:
Questo lavoro tratta della programmazione oraria di breve termine (una settimana prima) di impianti di cogenerazione all'interno di grandi siti industriali, dove la richiesta di calore e molto alta ed è fondamentale per i processi industriali.
Questa ottimizzazione ha lo scopo di trovare i punti di funzionamento dell¿impianto di cogenerazione che massimizzano i profitti derivanti dalla vendita del calore e dell'elettricità. Il prezzo dell'energia deve essere oggetto di previsione, in quanto dipende dagli esiti del mercato del giorno prima, mentre il prezzo del calore è legato a contratti di lungo termine tra il produttore delle utilities e le controparti del sito industriale.
Questi punti di funzionamento devono soddisfare vincoli tecnici, normativi ed economici; in particolare, devono essere soddisfatti gli indici di cogenerazione imposti dalla normativa italiana per consentire all'impianto di ottenere importanti benefici economici, come l'esenzione dall'obbligo di acquisto dei certificati verdi e la priorità di dispacciamento.
E' stata sviluppata un'applicazione Matlab per una generica e tipica configurazione di un impianto di cogenerazione, costituito sia da unità con turbine a gas a ciclo combinato e sia da unità a contropressione.
La procedura di ottimizzazione è stata applicata ad un case study costituitoda un impianto formato da due unità con turbine a gas a ciclo combinato e duè unità a contropressione.
Le relazioni che permettono di valutare le produzioni (calore ed elettricità) ed i consumi (combustibili) delle unità sono state calcolate utilizzando dati sperimentali e dati dei costruttori.
E' opportuno evidenziare che l'applicazione del metodo di ottimizzazione assicura il soddisfacimento degli indici di cogenerazione e consente di incrementare il profitto annuale dell'impianto di circa il 6% rispetto alla tipica gestione di un impianto di cogenerazione basata su una ripartizione della richiesta di vapore tra le varie unità prefissata.