Applicazione ed integrazione di metodi di prospezione geofisica: studio idrogeofisico della Zona Insatura in condizioni idriche controllate

Il lavoro è incentrato sull’applicazione ed integrazione di differenti tecniche di indagine geofisica in campo ambientale e ingegneristico/archeologico. Alcuni esempi sono stati descritti al fine di dimostrare l’utilità delle metodologie geofisiche nella risoluzione di svariate problematiche. Nello specifico l’attenzione è stata rivolta all’utilizzo delle tecniche del Ground Penetrating Radar e del Time Domain Reflectometry in misure condotte su un corpo sabbioso simulante una Zona Insatura. L’esperimento è stato realizzato all’interno di un’area test costruita presso l’azienda agricola dell’Università La Tuscia di Viterbo. Hanno partecipato al progetto le Università di Roma Tre, Roma La Sapienza, La Tuscia, con il supporto tecnico della Sensore&Software. Nello studio è stato condotto un approccio definito idrogeofisico al fine di ottenere informazioni da misure dei parametri fisici relativi alla Zona Insatura simulata nell’area test. Il confronto e l’integrazione delle due differenti tecniche di indagine ha offerto la possibilità di estendere la profondità di indagine all’interno del corpo sabbioso e di verificare l’utilità della tecnica GPR nello studio degli effetti legati alle variazioni del contenuto d’acqua nel suolo, oltre a determinare la posizione della superficie piezometrica per i differenti scenari di saturazione. Uno specifico studio è stato realizzato sul segnale radar al fine di stabilire i fattori di influenza sulla sua propagazione all’interno del suolo. Il comportamento dei parametri dielettrici nelle condizioni di drenaggio e di imbibizione del corpo sabbioso è stato riprodotto attraverso una modellizzazione delle proprietà dielettriche ed idrologiche sulla base della dimensione, forma e distribuzione dei granuli di roccia e pori, nonché sulla base della storia relativa alla distribuzione dei fluidi di saturazione all’interno del mezzo. La modellizzazione è stata operata sulle basi concettuali del Differential Effective Medium Approximation.

Strumenti e metodi per lo sviluppo prodotto di lenti oftalmiche

The recent introduction of free form NC machining in the ophthalmic field involved a full review of the former product development process both from the design and the manufacturing viewpoint. Aim of the present work is to investigate and to set up innovative methods and tools supporting the product development, particularly for lenses characterized by free form geometry, as e.g. progressive lenses. In the design stage, the research addressed geometric modeling of complex lens shapes and relevant analysis tools for the optical-geometrical characterization of the produced models. In the manufacturing stage, the main interest was focused on the set-up of the fabrication process, particularly on the NC machining process for which an integration CADCAM software was developed for the generation and the simulation of the machining cycle. The methodologies and tools made available by the present work are currently used in the development of new complex geometry product typologies as, e.g. progressive lenses.

Modellazione e simulazione di sistemi meccanici ad elevato numero di gradi di libertà mediante metodi non convenzionali e sistemi CAD

Recent developments in piston engine technology have increased performance in a very significant way. Diesel turbocharged/turbo compound engines, fuelled by jet fuels, have great performances. The focal point of this thesis is the transformation of the FIAT 1900 jtd diesel common rail engine for the installation on general aviation aircrafts like the CESSNA 172. All considerations about the diesel engine are supported by the studies that have taken place in the laboratories of the II Faculty of Engineering in Forlì. This work, mostly experimental, concerns the transformation of the automotive FIAT 1900 jtd – 4 cylinders – turbocharged – diesel common rail into an aircraft engine. The design philosophy of the aluminium alloy basement of the spark ignition engine have been transferred to the diesel version while the pistons and the head of the FIAT 1900 jtd are kept in the aircraft engine. Different solutions have been examined in this work. A first V 90° cylinders version that can develop up to 300 CV and whose weight is 30 kg, without auxiliaries and turbocharging group. The second version is a development of e original version of the diesel 1900 cc engine with an optimized crankshaft, that employ a special steel, 300M, and that is verified for the aircraft requirements. Another version with an augmented stroke and with a total displacement of 2500 cc has been examined; the result is a 30% engine heavier. The last version proposed is a 1600 cc diesel engine that work at 5000 rpm, with a reduced stroke and capable of more than 200 CV; it was inspired to the Yamaha R1 motorcycle engine. The diesel aircraft engine design keeps the bore of 82 mm, while the stroke is reduced to 64.6 mm, so the engine size is reduced along with weight. The basement weight, in GD AlSi 9 MgMn alloy, is 8,5 kg. Crankshaft, rods and accessories have been redesigned to comply to aircraft standards. The result is that the overall size is increased of only the 8% when referred to the Yamaha engine spark ignition version, while the basement weight increases of 53 %, even if the bore of the diesel version is 11% lager. The original FIAT 1900 jtd piston has been slightly modified with the combustion chamber reworked to the compression ratio of 15:1. The material adopted for the piston is the aluminium alloy A390.0-T5 commonly used in the automotive field. The piston weight is 0,5 kg for the diesel engine. The crankshaft is verified to torsional vibrations according to the Lloyd register of shipping requirements. The 300M special steel crankshaft total weight is of 14,5 kg. The result reached is a very small and light engine that may be certified for general aviation: the engine weight, without the supercharger, air inlet assembly, auxiliary generators and high pressure body, is 44,7 kg and the total engine weight, with enlightened HP pump body and the titanium alloy turbocharger is less than 100 kg, the total displacement is 1365 cm3 and the estimated output power is 220 CV. The direct conversion of automotive piston engine to aircrafts pays too huge weight penalties. In fact the main aircraft requirement is to optimize the power to weight ratio in order to obtain compact and fast engines for aeronautical use: this 1600 common rail diesel engine version demonstrates that these results can be reached.

Metodi numerici per lo studio di centri di lavoro ad alta velocità

A Machining Centre is nowadays a complex mechanical, electronic, electrical system that needs integrated design capabilities which very often require a high time-consuming effort. Numerical techniques for designing and dimensioning the machine structure and components usually requires different knowledge according to the system that have to be designed. This Ph. D Thesis is related about the efforts of the Authors to develop a system that allows to perform the complete project of a new machine optimized in its dynamic behaviour. An integration of the different systems developed, each of which respond to specific necessities of designer, is here presented. In particular a dynamic analysis system, based on a lumped mass approach, that rapidly allows to setup the drives of the machine and an Integrated Dynamic Simulation System, based on a FEM approach, that permit a dynamic optimization, are shown. A multilevel Data Base, and an operator interface module provide to complete the designing platform. The proposed approach represents a significant step toward the virtual machining for the prediction of the quality of the worked surface.

Metodi molecolari nello studio della variabilità genetica di Tuber borchii

Tuber borchii (Ascomycota, order Pezizales) is highly valued truffle sold in local markets in Italy. Despite its economic importance, knowledge on its distribution and population variation is scarce. The objective of this work was to investigate the evolutionary forces shaping the genetic structure of this fungus using coalescent and phylogenetic methods to reconstruct the evolutionary history of populations in Italy. To assess population structure, 61 specimens were collected from 11 different Provinces of Italy. Sampling was stratified across hosts and habitats to maximize coverage in native oak and pine stands and both mychorrizae and fruiting bodies were collected. Samples were identified considering anatomo-morphological characters. DNA was extracted and both multilocus (AFLP) and single-locus (18 loci from rDNA, nDNA, and mtDNA) approaches were used to look for polymorphisms. Screening AFLP profiles, both Jaccard and Dice coefficients of similarity were utilized to transform binary matrix into a distance matrix and then to desume Neighbour-Joining trees. Though these are only preliminary examinations, phylogenetic trees were totally concordant with those deriving from single locus analyses. Phylogenetic analyses of the nuclear loci were performed using maximum likelihood with PAUP and a combined phylogenetic inference, using Bayesian estimation with all nuclear gene regions, was carried out. To reconstruct the evolutionary history, we estimated recurrent migration, migration across the history of the sample, and estimated the mutation and approximate age of mutations in each tree using SNAP Workbench. The combined phylogenetic tree using Bayesian estimation suggests that there are two main haplotypes that are difficult to be differentiated on the basis of morphology, of ecological parameters and symbiontic tree. Between these two lineages, that occur in sympatry within T. borchii populations, there is no evidence of recurrent migration. However, migration over the history of the sample was asymmetrical suggesting that isolation was a result of interrupted gene flow followed by range expansion. Low levels of divergence between the haplotypes indicate that there are likely to be two cryptic species within the T. borchii population sampled. Our results suggest that isolation between populations of T. borchii could have led to reproductive isolation between two lineages. This isolation is likely due to sympatric speciation caused by a multiple colonization from different refugia or a recent isolation. In attempting to determinate whether these haplotypes represent separate species or a partition of the same species we applied Biological and Mechanistic species Concepts. Notwithstanding, further analyses are necessary to evaluate if selection favoured premating or post-mating isolation.