Search results for "Numerical"
showing 10 items of 2002 documents
Role of the N-*(1535) in the J/psi -> pp and J/psi -> p(+)Lambda reactions
2009
We study the J/psi -> p eta p and J/psi -> pK(+)Lambda reactions with a unitary chiral approach. We find that the unitary chiral approach, which generates the N-*(1535) dynamically, can describe the data reasonably well, particularly the ratio of the integrated cross sections. This study provides further support for the unitary chiral description of the N-*(1535). We also discuss some subtle differences between the coupling constants determined from the unitary chiral approach and those determined from phenomenological studies
Rotational effects on the oscillation frequencies of newly born proto-neutron stars
2003
In this paper we study the effects of rotation on the frequencies of the quasi-normal modes of a proto-neutron star (PNS) born in a gravitational collapse during the first minute of life. Our analysis starts a few tenths of seconds after the PNS formation, when the stellar evolution can be described by a sequence of equilibrium configurations. We use the evolutionary models developed by Pons et al. (1999; 2001) that describe how a non rotating star cools down and contracts while neutrino diffusion and thermalization processes dominate the stellar dynamics. For assigned values of the evolution time, we set the star into slow rotation and integrate the equations of stellar perturbations in th…
Residual a posteriori error estimation for frictional contact with Nitsche method
2023
We consider frictional contact problems in small strain elasticity discretized with finite elements and Nitsche method. Both bilateral and unilateral contact problems are taken into account, as well as both Tresca and Coulomb models for the friction. We derive residual a posteriori error estimates for each friction model, following [Chouly et al, IMA J. Numer. Anal. (38) 2018, pp. 921-954]. For the incomplete variant of Nitsche, we prove an upper bound for the dual norm of the residual, for Tresca and Coulomb friction, without any extra regularity and without a saturation assumption. Numerical experiments allow to assess the accuracy of the estimates and their interest for adaptive meshing …
Numerical simulation of non-equilibrium sediment transport in a flume
2012
Rocking behaviour of multi-block columns subjected to pulse-typeground motion accelerations
2016
Ancient columns, made with a variety of materials such as marble, granite, stone or masonry are an important part of theEuropean cultural heritage. In particular columns of ancient temples in Greece and Sicily which support only the architrave arecharacterized by small axial load values. This feature together with the slenderness typical of these structural members clearlyhighlights as the evaluation of the rocking behaviour is a key aspect of their safety assessment and maintenance. It has to be notedthat the rocking response of rectangular cross-sectional columns modelled as monolithic rigid elements, has been widely investigatedsince the first theoretical study carried out by Housner (19…
Improving the Downwind Sail Design Process by Means of a Novel FSI Approach
2021
The process of designing a sail can be a challenging task because of the difficulties in predicting the real aerodynamic performance. This is especially true in the case of downwind sails, where the evaluation of the real shapes and aerodynamic forces can be very complex because of turbulent and detached flows and the high-deformable behavior of structures. Of course, numerical methods are very useful and reliable tools to investigate sail performances, and their use, also as a result of the exponential growth of computational resources at a very low cost, is spreading more and more, even in not highly competitive fields. This paper presents a new methodology to support sail designers in ev…
Inserimento di restringimenti e ponti in un modello diffusivo 2D di acque basse
2010
Gli effetti su una corrente, causati dalle pile di un ponte, o più in generale da strutture che riducono la sezione trasversale dell’alveo, risultano di particolare interesse per le variazioni idrometriche che comportano alla corrente stessa. Nonostante i numerosi studi teorici e sperimentali di letteratura, l’attuale modellistica numerica diffusiva non integra la presenza di tali manufatti nelle proprie tecniche risolutive. Nella presente memoria viene presentata la metodologia implementata nel modello diffusivo bidimensionale FLOW2D per la valutazione del rigurgito provocato da restringimenti della sezione trasversale, nonché dalla presenza delle campate. I profili di rigurgito ottenuti c…
A comprehensive guide to the physics and usage of PYTHIA 8.3
2022
This manual describes the PYTHIA 8.3 event generator, the most recent version of an evolving physics tool used to answer fundamental questions in particle physics. The program is most often used to generate high-energy-physics collision "events", i.e. sets of particles produced in association with the collision of two incoming high-energy particles, but has several uses beyond that. The guiding philosophy is to produce and reproduce properties of experimentally obtained collisions as accurately as possible. The program includes a wide ranges of reactions within and beyond the Standard Model, and extending to heavy ion physics. Emphasis is put on phenomena where strong interactions play a ma…
Numerical methods for a nonlinear impact model: A comparative study with closed-form corrections
2011
A physically based impact model-already known and exploited in the field of sound synthesis-is studied using both analytical tools and numerical simulations. It is shown that the Hamiltonian of a physical system composed of a mass impacting on a wall can be expressed analytically as a function of the mass velocity during contact. Moreover, an efficient and accurate approximation for the mass outbound velocity is presented, which allows to estimate the Hamiltonian at the end of the contact. Analytical results are then compared to numerical simulations obtained by discretizing the system with several numerical methods. It is shown that, for some regions of the parameter space, the trajectorie…