Simulation of bistatic radar experiments with deep space missions

L’obiettivo del lavoro esposto nella seguente relazione di tesi ha riguardato lo studio e la simulazione di esperimenti di radar bistatico per missioni di esplorazione planeteria. In particolare, il lavoro si è concentrato sull’uso ed il miglioramento di un simulatore software già realizzato da un consorzio di aziende ed enti di ricerca nell’ambito di uno studio dell’Agenzia Spaziale Europea (European Space Agency – ESA) finanziato nel 2008, e svolto fra il 2009 e 2010. L’azienda spagnola GMV ha coordinato lo studio, al quale presero parte anche gruppi di ricerca dell’Università di Roma “Sapienza” e dell’Università di Bologna. Il lavoro svolto si è incentrato sulla determinazione della causa di alcune inconsistenze negli output relativi alla parte del simulatore, progettato in ambiente MATLAB, finalizzato alla stima delle caratteristiche della superficie di Titano, in particolare la costante dielettrica e la rugosità media della superficie, mediante un esperimento con radar bistatico in modalità downlink eseguito dalla sonda Cassini-Huygens in orbita intorno al Titano stesso. Esperimenti con radar bistatico per lo studio di corpi celesti sono presenti nella storia dell’esplorazione spaziale fin dagli anni ’60, anche se ogni volta le apparecchiature utilizzate e le fasi di missione, durante le quali questi esperimenti erano effettuati, non sono state mai appositamente progettate per lo scopo. Da qui la necessità di progettare un simulatore per studiare varie possibili modalità di esperimenti con radar bistatico in diversi tipi di missione. In una prima fase di approccio al simulatore, il lavoro si è incentrato sullo studio della documentazione in allegato al codice così da avere un’idea generale della sua struttura e funzionamento. È seguita poi una fase di studio dettagliato, determinando lo scopo di ogni linea di codice utilizzata, nonché la verifica in letteratura delle formule e dei modelli utilizzati per la determinazione di diversi parametri. In una seconda fase il lavoro ha previsto l’intervento diretto sul codice con una serie di indagini volte a determinarne la coerenza e l’attendibilità dei risultati. Ogni indagine ha previsto una diminuzione delle ipotesi semplificative imposte al modello utilizzato in modo tale da identificare con maggiore sicurezza la parte del codice responsabile dell’inesattezza degli output del simulatore. I risultati ottenuti hanno permesso la correzione di alcune parti del codice e la determinazione della principale fonte di errore sugli output, circoscrivendo l’oggetto di studio per future indagini mirate.

Calibration of the detector flight models for the HERMES and SPIRIT nanosatellite missions

The High Energy Rapid Modular Ensemble of Satellites (HERMES) is a new mission concept involving the development of a constellation of six CubeSats in low Earth orbit with new miniaturized instruments that host a hybrid Silicon Drift Detector/GAGG:Ce based system for X-ray and γ-ray detection, aiming to monitor high-energy cosmic transients, such as Gamma Ray Bursts and the electromagnetic counterparts of gravitational wave events. The HERMES constellation will also operate together with the Australian-Italian SpIRIT mission, which will house a HERMES-like detector. The HERMES pathfinder mini-constellation, consisting of six satellites plus SpIRIT, is likely to be launched in 2023. The HERMES detectors are based on the heritage of the Italian ReDSoX collaboration, with joint design and production by INFN-Trieste and Fondazione Bruno Kessler, and the involvement of several Italian research institutes and universities. An application-specific, low-noise, low-power integrated circuit (ASIC) called LYRA was conceived and designed for the HERMES readout electronics. My thesis project focuses on the ground calibrations of the first HERMES and SpIRIT flight detectors, with a performance assessment and characterization of the detectors. The first part of this work addresses measurements and experimental tests on laboratory prototypes of the HERMES detectors and their front-end electronics, while the second part is based on the design of the experimental setup for flight detector calibrations and related functional tests for data acquisition, as well as the development of the calibration software. In more detail, the calibration parameters (such as the gain of each detector channel) are determined using measurements with radioactive sources, performed at different operating temperatures between -20°C and +20°C by placing the detector in a suitable climate chamber. The final part of the thesis involves the analysis of the calibration data and a discussion of the results.

Analysis of aircraft load spectrum by means of flight simulator

Damage tolerance analysis is a quite new methodology based on prescribed inspections. The load spectra used to derive results of these analysis strongly influence the final defined inspections programs that for this reason must be as much as possible representative of load acting on the considered structural component and at the same time, obtained reducing both cost and time. The principal purpose of our work is in improving the actual condition developing a complete numerical Damage Tolerance analysis, able to prescribe inspection programs on typical aircraft critical components, respecting DT regulations, starting from much more specific load spectrum then those actually used today. In particular, these more specific load spectrum to design against fatigue have been obtained through an appositively derived flight simulator developed in a Matlab/Simulink environment. This dynamic model has been designed so that it can be used to simulate typical missions performing manually (joystick inputs) or completely automatic (reference trajectory need to be provided) flights. Once these flights have been simulated, model’s outputs are used to generate load spectrum that are then processed to get information (peaks, valleys) to perform statistical and/or comparison consideration with other load spectrum. However, also much more useful information (loads amplitude) have been extracted from these generated load spectrum to perform the previously mentioned predictions (Rainflow counting method is applied for this purpose). The entire developed methodology works in a complete automatic way, so that, once some specified input parameters have been introduced and different typical flights have been simulated both, manually or automatically, it is able to relate the effects of these simulated flights with the reduction of residual strength of the considered component.

Una scossa all'economia: le conseguenze del sisma dell'Aquilano. Traduzione dall'inglese in italiano di un articolo di ricerca economica ed esperienza di collaborazione con gli autori.

The aim of this dissertation is to provide a translation from English into Italian of a specialised scientific article published in the Cambridge Working Papers in Economics series. In this text, the authors estimate the economic consequences of the earthquake that hit the Abruzzo region in 2009. An extract of this translation will be published as part of conference proceedings. The main reason behind this choice is a personal interest in specialised translation in the economic domain. Moreover, the subject of the article is of particular interest to the Italian readership. The aim of this study is to show how a non-specialised translator can tackle with such a highly specialised translation with the use of appropriate terminology resources and the collaboration of field experts. The translation could be of help to other Italian linguists looking for translated material in this particular domain where English seems to be the dominant language. In order to ensure consistent terminology and adequate style, the document has been translated with the use of different resources, such as dictionaries, glossaries and specialised corpora. I also contacted field experts and the authors of text. The collaboration with the authors proved to be an invaluable resource yet one to be carefully managed. This work is divided into 5 chapters. The first deals with domain-specific sublanguages. The second gives an overview of corpus linguistics and describes the corpora designed for the translation. The third provides an analysis of the article, focusing on syntactical, lexical and structural features while the fourth presents the translation, side-by-side with the source text. The fifth comments on the main difficulties encountered in the translation and the strategies used, as well as the relationship with the authors and their review of the published text. Appendix I contains the econometric glossary English – Italian.

Night Vision Imaging System (NVIS) certification requirements analysis of an Airbus Helicopters H135

The safe operation of nighttime flight missions would be enhanced using Night Vision Imaging Systems (NVIS) equipment. This has been clear to the military since 1970s and to the civil helicopters since 1990s. In these last months, even Italian Emergency Medical Service (EMS) operators require Night Vision Goggles (NVG) devices that therefore amplify the ambient light. In order to fly with this technology, helicopters have to be NVIS-approved. The author have supported a company, to quantify the potentiality of undertaking the certification activity, through a feasibility study. Even before, NVG description and working principles have been done, then specifications analysis about the processes to make a helicopter NVIS-approved has been addressed. The noteworthy difference between military specifications and the civilian ones highlights non-irrevelant lacks in the latter. The activity of NVIS certification could be a good investment because the following targets have been achieved: Reductions of the certification cost, of the operating time and of the number of non-compliance.

Esperienza di creazione di entrate lessicografiche combinatorie: metodi e dati dal progetto CombiNet

The present dissertation aims at simulating the construction of lexicographic layouts for an Italian combinatory dictionary based on real linguistic data, extracted from corpora by using computational methods. This work is based on the assumption that the intuition of the native speaker, or the lexicographer, who manually extracts and classifies all the relevant data, are not adequate to provide sufficient information on the meaning and use of words. Therefore, a study of the real use of language is required and this is particularly true for dictionaries that collect the combinatory behaviour of words, where the task of the lexicographer is to identify typical combinations where a word occurs. This study is conducted in the framework of the CombiNet project aimed at studying Italian Word Combinationsand and at building an online, corpus-based combinatory lexicographic resource for the Italian language. This work is divided into three chapters. Chapter 1 describes the criteria considered for the classification of word combinations according to the work of Ježek (2011). Chapter 1 also contains a brief comparison between the most important Italian combinatory dictionaries and the BBI Dictionary of Word Combinations in order to describe how word combinations are considered in these lexicographic resources. Chapter 2 describes the main computational methods used for the extraction of word combinations from corpora, taking into account the advantages and disadvantages of the two methods. Chapter 3 mainly focuses on the practical word carried out in the framework of the CombiNet project, with reference to the tools and resources used (EXTra, LexIt and "La Repubblica" corpus). Finally, the data extracted and the lexicographic layout of the lemmas to be included in the combinatory dictionary are commented, namely the words "acqua" (water), "braccio" (arm) and "colpo" (blow, shot, stroke).