Browsing by Author "Greco, Francesco"

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    Advanced numerical methods for material forming and cutting
    (2013-11-19) Greco, Francesco; Filice, Luigino; Pagnotta, Leonardo
    The nite element method is the reference technique in the simulation of metal forming and provides excellent results with both Eulerian and Lagrangian implementations. The latter approach is more natural and direct but the large deformations involved in such processes require remeshing-rezoning algorithms that increase the computational times and a ect the quality of the results. For this reasons alternative techniques based on modi ed FEM formulations or meshless approximants are worth to be investigated. In particular, in this project, the nite element method with nodal integration and the maximum entropy meshfree approximants are studied and applied to the simulation of selected problems in metal forming and orthogonal cutting. Il metodo degli elementi niti e attualmente la tecnica di riferimento nella simulazione di processi di formatura e fornisce ottimi risultati sia con formulazioni Euleriane che Lagranzgiane. Quest'ultimo approccio e pi u naturale e diretto ma le grosse deformazioni che entrano in gioco in questi processi richiedono l'applicazione di algoritmi di remeshing-rezoning che aumentano i tempi computazionali e peggiorano la qualit a dei risultati. Per questi motivi assume particolare interesse lo sviluppo di tecniche alternative, basate su formulazioni FEM modi cate o su approssimazioni senza maglia (meshless). In particolare, in questo lavoro, sono studiati il metodo degli elementi niti con integrazione nodale e le tecniche meshless di tipo maximum entropy e, inoltre, sono applicati alla simulazione di processi di formatura e taglio
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    mm-Wave Antennas For Satellite And Mobile Communications
    (2017-07-26) Greco, Francesco; Crupi, Felice; Amendola, Giandomenico
    Ever growing demands for higher data rate and bandwidth are pushing wireless applications to millimetre-wave band (3-300GHz), where sufficient bandwidth is available and high performance can be achieved without using complex modulation systems. In addition to Telecom applications, millimetre-wave bands has enabled novel short range and long range radar sensors for automotive as well as high resolution imaging systems for medical and security. The major obstacle for the wide deployment of commercial wireless and radar systems in this frequency range is the high cost of the overall system. The main object of this work is to investigate and to develop different type of antenna that could be applied in satellite communications, in the future fifth generation of mobile networks and on radar automotive systems. In particular, in the present thesis, four antennas have been developed. A dual band dual polarized antenna array for Satcom-On-The-Move application that gives the possibility to obtain a fixed beam on the frequency range 19-21GHz (Rx band) and 29-31GHz (Tx band). This structure could be used in association with a fully mechanical pointing system. A Reflector terminal in the Q/V bands that could be use on the backhaul point of the 5G future architecture. A Ka band scaled version of the antenna has been realized and measured proving that it can be a valid solution for compact earth terminals. A novel reflectarray with potential applications in both satellite communications and high speed point-to-point radio links. Finally, a 77GHz transmit-array antenna mounted on a QFN package. This kind structure, due to the compact dimensions, could be represent a possible solution for automotive radar system