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International audience; A generalized multi-fidelity (MF) metamodel of CFD (computational fluid dynamics) computations is presented for design-and operational-space exploration, based on machine learning from an arbitrary number of fidelity levels. The method is based on stochastic radial basis functions (RBF) with least squares regression and in-the-loop optimization of RBF parameters to deal with noisy data. The method is intended to accurately predict ship performance while reducing the computational effort required by simulation-based optimization (SBDO) and/or uncertainty quantification problems. The present formulation here exploits the potential of simulation methods that naturally produce results spanning a range of fidelity levels through adaptive grid refinement and/or multi-grid resolution (i.e. varying the grid resolution). The performance of the method is assessed for one analytical test and three SBDO problems based on CFD simulations, namely a NACA hydrofoil, the DTMB 5415 model, and a roll-on/roll-off passenger ferry in calm water. Under the assumption of a limited budget of function evaluations, the proposed MF method shows better performance in comparison with its single-fidelity counterpart. The method also shows very promising results in dealing with and learning from noisy CFD data.

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The hydrodynamics of a ship in prescribed motionis addressed by unsteady simulations using a hybridRANS/BEM solver. The interactive methodology com-bines a viscous-flow model addressing the flow aroundthe ship with a potential-flow model describing the loadsinduced by the vorticity generated at the propeller. Animplicit iterative procedure is provided in the time cy-cle through a body-force/effective inflow approach. Thepresent model is validated through comparisons about thevelocity flow-field and blade loads of numerical predictionsand measurements collected during an experimental cam-paign of a ship model in calm water moving in straightahead and steady drift motion. In particular, the nomi-nal tridimensional flow at the propeller disc is providedby the application of a stereo PIV technique, based on theuse of boroscopic equipment, whereas the transient singleblade loads are collected using a novel set-up adopting a 6-component multi-axial force transducer constrained at theroot blade itself. In spite of the inability of the model to ac-count for the blade boundary layer, the flow-field descrip-tion is detailed enough outside the propeller region whileassuring a limited computational burden related to meshgeneration. The present methodology represents a viablesolution to address the flow of maneouvring ships.

The nuclei 11Be and 11Li provide paradigmatic examples of one-and two- neutron halo systems. Because the reaction 1H(11Li,9Li)3H is dominated by successive transfer, one can use the quantitative picture emerging from a nu- clear field theory description of the structure and reaction mechanism of the above Cooper pair transfer process and of the 2H(10Be,11Be)1H and 1H(11Be,10Be)2H reactions, to shed light on the structure of 10Li. This analysis provides important support for a parity inverted scenario with a 1/2+ virtual state at about 0.2 MeV., Proceedings of the 15th Varenna Conference on Nuclear Reaction Mechanisms