Paralelización del código de desenredo y suavizado de mallas de tetraedros "S.U.S Code"

Máster Universitario en Sistemas Inteligentes y Aplicaciones Numéricas en Ingeniería (SIANI)

CMOS RF front-end receivers for DVB-SH

Programa de doctorado: Ingeniería de Telecomunicación Avanzada.

Automatic code generation: from process algebraic architectural descriptions to multithreaded java programs

Process algebraic architectural description languages provide a formal means for modeling software systems and assessing their properties. In order to bridge the gap between system modeling and system im- plementation, in this thesis an approach is proposed for automatically generating multithreaded object-oriented code from process algebraic architectural descriptions, in a way that preserves – under certain assumptions – the properties proved at the architectural level. The approach is divided into three phases, which are illustrated by means of a running example based on an audio processing system. First, we develop an architecture-driven technique for thread coordination management, which is completely automated through a suitable package. Second, we address the translation of the algebraically-specified behavior of the individual software units into thread templates, which will have to be filled in by the software developer according to certain guidelines. Third, we discuss performance issues related to the suitability of synthesizing monitors rather than threads from software unit descriptions that satisfy specific constraints. In addition to the running example, we present two case studies about a video animation repainting system and the implementation of a leader election algorithm, in order to summarize the whole approach. The outcome of this thesis is the implementation of the proposed approach in a translator called PADL2Java and its integration in the architecture-centric verification tool TwoTowers.

Towards model driven software development for Arduino platforms: a DSL and automatic code generation

La tesi ha lo scopo di esplorare la produzione di sistemi software per Embedded Systems mediante l'utilizzo di tecniche relative al mondo del Model Driven Software Development. La fase più importante dello sviluppo sarà la definizione di un Meta-Modello che caratterizza i concetti fondamentali relativi agli embedded systems. Tale modello cercherà di astrarre dalla particolare piattaforma utilizzata ed individuare quali astrazioni caratterizzano il mondo degli embedded systems in generale. Tale meta-modello sarà quindi di tipo platform-independent. Per la generazione automatica di codice è stata adottata una piattaforma di riferimento, cioè Arduino. Arduino è un sistema embedded che si sta sempre più affermando perché coniuga un buon livello di performance ed un prezzo relativamente basso. Tale piattaforma permette lo sviluppo di sistemi special purpose che utilizzano sensori ed attuatori di vario genere, facilmente connessi ai pin messi a disposizione. Il meta-modello definito è un'istanza del meta-metamodello MOF, definito formalmente dall'organizzazione OMG. Questo permette allo sviluppatore di pensare ad un sistema sotto forma di modello, istanza del meta-modello definito. Un meta-modello può essere considerato anche come la sintassi astratta di un linguaggio, quindi può essere definito da un insieme di regole EBNF. La tecnologia utilizzata per la definizione del meta-modello è stata Xtext: un framework che permette la scrittura di regole EBNF e che genera automaticamente il modello Ecore associato al meta-modello definito. Ecore è l'implementazione di EMOF in ambiente Eclipse. Xtext genera inoltre dei plugin che permettono di avere un editor guidato dalla sintassi, definita nel meta-modello. La generazione automatica di codice è stata realizzata usando il linguaggio Xtend2. Tale linguaggio permette di esplorare l'Abstract Syntax Tree generato dalla traduzione del modello in Ecore e di generare tutti i file di codice necessari. Il codice generato fornisce praticamente tutta la schematic part dell'applicazione, mentre lascia all'application designer lo sviluppo della business logic. Dopo la definizione del meta-modello di un sistema embedded, il livello di astrazione è stato spostato più in alto, andando verso la definizione della parte di meta-modello relativa all'interazione di un sistema embedded con altri sistemi. Ci si è quindi spostati verso un ottica di Sistema, inteso come insieme di sistemi concentrati che interagiscono. Tale difinizione viene fatta dal punto di vista del sistema concentrato di cui si sta definendo il modello. Nella tesi viene inoltre introdotto un caso di studio che, anche se abbastanza semplice, fornisce un esempio ed un tutorial allo sviluppo di applicazioni mediante l'uso del meta-modello. Ci permette inoltre di notare come il compito dell'application designer diventi piuttosto semplice ed immediato, sempre se basato su una buona analisi del problema. I risultati ottenuti sono stati di buona qualità ed il meta-modello viene tradotto in codice che funziona correttamente.

Enabling Techniques and Algorithms for Integrated Communication and Navigation Satellite Systems

This thesis presents the outcomes of my Ph.D. course in telecommunications engineering. The focus of my research has been on Global Navigation Satellite Systems (GNSS) and in particular on the design of aiding schemes operating both at position and physical level and the evaluation of their feasibility and advantages. Assistance techniques at the position level are considered to enhance receiver availability in challenging scenarios where satellite visibility is limited. Novel positioning techniques relying on peer-to-peer interaction and exchange of information are thus introduced. More specifically two different techniques are proposed: the Pseudorange Sharing Algorithm (PSA), based on the exchange of GNSS data, that allows to obtain coarse positioning where the user has scarce satellite visibility, and the Hybrid approach, which also permits to improve the accuracy of the positioning solution. At the physical level, aiding schemes are investigated to improve the receiver’s ability to synchronize with satellite signals. An innovative code acquisition strategy for dual-band receivers, the Cross-Band Aiding (CBA) technique, is introduced to speed-up initial synchronization by exploiting the exchange of time references between the two bands. In addition vector configurations for code tracking are analyzed and their feedback generation process thoroughly investigated.

Design and implementation of a novel multi-constellation FPGA-based dual frequency GNSS receiver for space applications

The PhD activity described in the document is part of the Microsatellite and Microsystem Laboratory of the II Faculty of Engineering, University of Bologna. The main objective is the design and development of a GNSS receiver for the orbit determination of microsatellites in low earth orbit. The development starts from the electronic design and goes up to the implementation of the navigation algorithms, covering all the aspects that are involved in this type of applications. The use of GPS receivers for orbit determination is a consolidated application used in many space missions, but the development of the new GNSS system within few years, such as the European Galileo, the Chinese COMPASS and the Russian modernized GLONASS, proposes new challenges and offers new opportunities to increase the orbit determination performances. The evaluation of improvements coming from the new systems together with the implementation of a receiver that is compatible with at least one of the new systems, are the main activities of the PhD. The activities can be divided in three section: receiver requirements definition and prototype implementation, design and analysis of the GNSS signal tracking algorithms, and design and analysis of the navigation algorithms. The receiver prototype is based on a Virtex FPGA by Xilinx, and includes a PowerPC processor. The architecture follows the software defined radio paradigm, so most of signal processing is performed in software while only what is strictly necessary is done in hardware. The tracking algorithms are implemented as a combination of Phase Locked Loop and Frequency Locked Loop for the carrier, and Delay Locked Loop with variable bandwidth for the code. The navigation algorithm is based on the extended Kalman filter and includes an accurate LEO orbit model.

Analysis of optimal control problems for the incompressible MHD equations and implementation in a finite element multiphysics code

This thesis deals with the study of optimal control problems for the incompressible Magnetohydrodynamics (MHD) equations. Particular attention to these problems arises from several applications in science and engineering, such as fission nuclear reactors with liquid metal coolant and aluminum casting in metallurgy. In such applications it is of great interest to achieve the control on the fluid state variables through the action of the magnetic Lorentz force. In this thesis we investigate a class of boundary optimal control problems, in which the flow is controlled through the boundary conditions of the magnetic field. Due to their complexity, these problems present various challenges in the definition of an adequate solution approach, both from a theoretical and from a computational point of view. In this thesis we propose a new boundary control approach, based on lifting functions of the boundary conditions, which yields both theoretical and numerical advantages. With the introduction of lifting functions, boundary control problems can be formulated as extended distributed problems. We consider a systematic mathematical formulation of these problems in terms of the minimization of a cost functional constrained by the MHD equations. The existence of a solution to the flow equations and to the optimal control problem are shown. The Lagrange multiplier technique is used to derive an optimality system from which candidate solutions for the control problem can be obtained. In order to achieve the numerical solution of this system, a finite element approximation is considered for the discretization together with an appropriate gradient-type algorithm. A finite element object-oriented library has been developed to obtain a parallel and multigrid computational implementation of the optimality system based on a multiphysics approach. Numerical results of two- and three-dimensional computations show that a possible minimum for the control problem can be computed in a robust and accurate manner.

Genome characterization through a mathematical model of the genetic code: an analysis of the whole chromosome 1 of A. thaliana

The objective of this work is to characterize the genome of the chromosome 1 of A.thaliana, a small flowering plants used as a model organism in studies of biology and genetics, on the basis of a recent mathematical model of the genetic code. I analyze and compare different portions of the genome: genes, exons, coding sequences (CDS), introns, long introns, intergenes, untranslated regions (UTR) and regulatory sequences. In order to accomplish the task, I transformed nucleotide sequences into binary sequences based on the definition of the three different dichotomic classes. The descriptive analysis of binary strings indicate the presence of regularities in each portion of the genome considered. In particular, there are remarkable differences between coding sequences (CDS and exons) and non-coding sequences, suggesting that the frame is important only for coding sequences and that dichotomic classes can be useful to recognize them. Then, I assessed the existence of short-range dependence between binary sequences computed on the basis of the different dichotomic classes. I used three different measures of dependence: the well-known chi-squared test and two indices derived from the concept of entropy i.e. Mutual Information (MI) and Sρ, a normalized version of the “Bhattacharya Hellinger Matusita distance”. The results show that there is a significant short-range dependence structure only for the coding sequences whose existence is a clue of an underlying error detection and correction mechanism. No doubt, further studies are needed in order to assess how the information carried by dichotomic classes could discriminate between coding and noncoding sequence and, therefore, contribute to unveil the role of the mathematical structure in error detection and correction mechanisms. Still, I have shown the potential of the approach presented for understanding the management of genetic information.

Validation of the CFD code NEPTUNE for a full scale simulator for decay heat removal systems with in-pool heat exchangers

In the present work, a multi physics simulation of an innovative safety system for light water nuclear reactor is performed, with the aim to increase the reliability of its main decay heat removal system. The system studied, denoted by the acronym PERSEO (in Pool Energy Removal System for Emergency Operation) is able to remove the decay power from the primary side of the light water nuclear reactor through a heat suppression pool. The experimental facility, located at SIET laboratories (PIACENZA), is an evolution of the Thermal Valve concept where the triggering valve is installed liquid side, on a line connecting two pools at the bottom. During the normal operation, the valve is closed, while in emergency conditions it opens, the heat exchanger is flooded with consequent heat transfer from the primary side to the pool side. In order to verify the correct system behavior during long term accidental transient, two main experimental PERSEO tests are analyzed. For this purpose, a coupling between the mono dimensional system code CATHARE, which reproduces the system scale behavior, with a three-dimensional CFD code NEPTUNE CFD, allowing a full investigation of the pools and the injector, is implemented. The coupling between the two codes is realized through the boundary conditions. In a first analysis, the facility is simulated by the system code CATHARE V2.5 to validate the results with the experimental data. The comparison of the numerical results obtained shows a different void distribution during the boiling conditions inside the heat suppression pool for the two cases of single nodalization and three volume nodalization scheme of the pool. Finaly, to improve the investigation capability of the void distribution inside the pool and the temperature stratification phenomena below the injector, a two and three dimensional CFD models with a simplified geometry of the system are adopted.

Sperimentazione con una libreria per la decodifica di bar code in immagini

In questa tesi viene studiata la libreria zbar.h il cui compito è decodificare i barcode presenti in immagini. Per acquisire le immagini si utilizzano funzioni contenute nella libreria OpenCV. Successivamente viene creata un'interfaccia tra OpenCV e ZBar. Vengono effettuati alcuni test per verificare l'efficienza sia di ZBar e sia dell'interfaccia. Concludendo, si crea una nuova libreria in cui sono inglobate le funzioni di ZBar e l'interfaccia OpenCV-ZBar

Cosmological predictions for a scalar tensor dark energy model by a dedicated Einstein-Boltzmann code

We have extended the Boltzmann code CLASS and studied a specific scalar tensor dark energy model: Induced Gravity