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Cangiani A.,University of Milan Bicocca | Natalini R.,CNR Institute for applied mathematics Mauro Picone
Journal of Theoretical Biology | Year: 2010

We consider models of Ran-driven nuclear transport of molecules such as proteins in living cells. The mathematical model presented is the first to take into account for the active transport of molecules along the cytoplasmic microtubules. All parameters entering the models are thoroughly discussed. The model is tested by numerical simulations based on discontinuous Galerkin finite element methods. The numerical experiments are compared to the behavior observed experimentally. © 2010 Elsevier Ltd. Source


Peri D.,CNR Institute for applied mathematics Mauro Picone
Ocean Engineering | Year: 2016

Robust Design Optimization (RDO) represents a really interesting opportunity when the specifications of the design are careful and accurate: the possibility to optimize an industrial object for the real usage situation, improving the overall performances while reducing the risk of occurrence of off-design conditions, strictly depends on the availability of the information about the probability of occurrence of the various operative conditions during the lifetime of the design. Those data are typically not available prior than the production of a prototype. However, once the design has been produced and is operative, navigation data can be collected and utilized for the modification (refitting) of the current design, possibly in an early stage of its lifetime, in order to adapt the design to the real operative conditions at a time when the lifetime is still long enough to allow the payback of the cost of the modification by the obtained savings. In the present paper, five sister ships have been observed for a time period of two months, recording their operative data. Statistical distribution of speed and displacement are derived. An optimization framework is then applied, and some modifications of a small portion of the hull are proposed in order to increase significantly the performances of the hull, decreasing the operative cost of the ship. Dedicated numerical techniques are adopted in order to reduce the time required for the re-design activities. © 2016 Elsevier Ltd Source


Gosse L.,CNR Institute for applied mathematics Mauro Picone
Computers and Mathematics with Applications | Year: 2010

We consider a rather simple algorithm to address the fascinating field of numerical extrapolation of (analytic) band-limited functions. It relies on two main elements: namely, the lower frequencies are treated by projecting the known part of the signal to be extended onto the space generated by "Prolate Spheroidal Wave Functions" (PSWF, as originally proposed by Slepian), whereas the higher ones can be handled by the recent so-called "Compressive Sampling" (CS, proposed by Candes) algorithms which are independent of the largeness of the bandwidth. Slepian functions are recalled and their numerical computation is explained in full detail, whereas ℓ1 regularization techniques are summarized together with a recent iterative algorithm which has been proved to work efficiently on so-called "compressible signals", which appear to match rather well the class of smooth bandlimited functions. Numerical results are displayed for both numerical techniques and the accuracy of the process consisting of putting them all together is studied for some test-signals showing a quite fast Fourier decay. © 2010 Elsevier Ltd. All rights reserved. Source


Bini D.,CNR Institute for applied mathematics Mauro Picone | Damour T.,Institute des Hautes etudes Scientifiques
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We complete the analytical determination, at the 4th post-Newtonian approximation, of the main radial potential describing the gravitational interaction of two bodies within the effective one-body formalism. The (nonlogarithmic) coefficient a5(ν) measuring this 4th post-Newtonian interaction potential is found to be linear in the symmetric mass ratio ν. Its ν-independent part a5(0) is obtained by an analytical gravitational self-force calculation that unambiguously resolves the formal infrared divergencies which currently impede its direct post-Newtonian calculation. Its ν-linear part a5(ν)-a5(0) is deduced from recent results of Jaranowski and Schäfer, and is found to be significantly negative. © 2013 American Physical Society. Source


Gosse L.,CNR Institute for applied mathematics Mauro Picone
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2011

An original well-balanced (WB) Godunov scheme relying on an exact Riemann solver involving a non-conservative (NC) product is developed. It is meant to solve accurately the time-dependent one-dimensional radiative transfer equation in the discrete ordinates approximation with an arbitrary even number of velocities. The collision term is thus concentrated onto a discrete lattice by means of Dirac masses; this induces steady contact discontinuities which are integral curves of the stationary problem. One solves it by taking advantage of the method of elementary solutions mainly developed by Case, Zweifel and Cercignani. This approach produces a rather simple scheme that compares advantageously to standard existing upwind schemes, especially for the decay in time toward a Maxwellian distribution. It is possible to reformulate this scheme in order to handle properly the parabolic scaling in order to generate a so-called asymptotic-preserving (AP) discretization. Consistency with the diffusive approximation holds independently of the computational grid. Several numerical results are displayed to show the realizability and the efficiency of the method. © 2011 Elsevier Ltd. Source

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