Design and Fabrication of Bond Wire Micro-Magnetics

This thesis presents a new approach for the design and fabrication of bond wire magnetics for power converter applications by using standard IC gold bonding wires and micro-machined magnetic cores. It shows a systematic design and characterization study for bond wire transformers with toroidal and race-track cores for both PCB and silicon substrates. Measurement results show that the use of ferrite cores increases the secondary self-inductance up to 315 µH with a Q-factor up to 24.5 at 100 kHz. Measurement results on LTCC core report an enhancement of the secondary self-inductance up to 23 µH with a Q-factor up to 10.5 at 1.4 MHz. A resonant DC-DC converter is designed in 0.32 µm BCD6s technology at STMicroelectronics with a depletion nmosfet and a bond wire micro-transformer for EH applications. Measures report that the circuit begins to oscillate from a TEG voltage of 280 mV while starts to convert from an input down to 330 mV to a rectified output of 0.8 V at an input of 400 mV. Bond wire magnetics is a cost-effective approach that enables a flexible design of inductors and transformers with high inductance and high turns ratio. Additionally, it supports the development of magnetics on top of the IC active circuitry for package and wafer level integrations, thus enabling the design of high density power components. This makes possible the evolution of PwrSiP and PwrSoC with reliable highly efficient magnetics.

Dynamic analysis of the motorcycle chattering behaviour by means of symbolic multibody modelling

Aim of this research is the development and validation of a comprehensive multibody motorcycle model featuring rigid-ring tires, taking into account both slope and roughness of road surfaces. A novel parametrization for the general kinematics of the motorcycle is proposed, using a mixed reference-point and relative-coordinates approach. The resulting description, developed in terms of dependent coordinates, makes it possible to efficiently include rigid-ring kinematics as well as road elevation and slope. The equations of motion for the multibody system are derived symbolically and the constraint equations arising from the dependent-coordinate formulation are handled using a projection technique. Therefore the resulting system of equations can be integrated in time domain using a standard ODE algorithm. The model is validated with respect to maneuvers experimentally measured on the race track, showing consistent results and excellent computational efficiency. More in detail, it is also capable of reproducing the chatter vibration of racing motorcycles. The chatter phenomenon, appearing during high speed cornering maneuvers, consists of a self-excited vertical oscillation of both the front and rear unsprung masses in the range of frequency between 17 and 22 Hz. A critical maneuver is numerically simulated, and a self-excited vibration appears, consistent with the experimentally measured chatter vibration. Finally, the driving mechanism for the self-excitation is highlighted and a physical interpretation is proposed.

Astroparticle physics with nuclear track detectors

This thesis is mainly about the search for exotic heavy particles -Intermediate Mass Magnetic Monopoles, Nuclearites and Q-balls with the SLIM experiment at the Chacaltaya High Altitude Laboratory (5230 m, Bolivia), establishing upper limits (90% CL) in the absence of candidates, which are among the best if not the only one for all three kind of particles. A preliminary study of the background induced by cosmic neutron in CR39 at the SLIM site, using Monte Carlo simulations. The measurement of the elemental abundance of the primary cosmic ray with the CAKE experiment on board of a stratospherical balloon; the charge distribution obtained spans in the range 5≤Z≤31. Both experiments were based on the use of plastic Nuclear Track Detectors, which records the passage of ionizing particles; by using some chemical reagents such passage can be make visible at optical microscopes.

«L’Eroica» e la xilografia italiana dal tardo simbolismo all’espressionismo (1911-1917)

Il lavoro di ricerca vuole analizzare, attraverso lo studio specifico della rivista artistico letteraria «L’Eroica» fondata a La Spezia nel 1911 da Ettore Cozzani e Franco Oliva, gli artisti e le situazioni in cui si sviluppa e si diffonde in Italia un linguaggio grafico di tipo fauve-espressionista, in perfetta sintonia con le coeve esperienze straniere. Nello specifico, si è focalizzata l’attenzione sui così detti ‘anni eroici de L’Eroica’ (1911-1917), periodo in cui risulta più evidente il passaggio che si ebbe nel panorama dell’illustrazione italiana da uno stile ancora riconducibile a un linguaggio simbolista a uno, per l’appunto espressionista. Questa rivista, infatti, nella fase conosciuta come “gli anni eroici dell’Eroica” (1911-17), s’interessa in modo quasi esclusivo alla xilografia contemporanea avvalendosi in un primo momento della collaborazione di artisti noti nell’ambito del gusto liberty come, ad esempio, Adolfo De Carolis e dei suoi allievi (Gino Barbieri, Ettore di Giorgio, Antonio Moroni). Tale collaborazione però termina con la cosiddetta “Secessione degli Xilografi”, ossia l’abbandono nel 1914 da parte di De Carolis e dei suoi della testata spezzina, circostanza questa che determinerà un nuovo indirizzo stilistico per la rivista in cui prenderanno sempre più spazio artisti di una generazione più giovane, peraltro già attivi su «L’Eroica» stessa, quali ad esempio Lorenzo Viani, Arturo Martini, Emilio Mantelli, Felice Casorati, Giuseppe Biasi, Roberto Melli e Gino Carlo Sensani, questi ultimi tutti rappresentanti di un espressionismo italiano di primo ordine