Search results for "Matematica"

Positive solutions for parametric singular Dirichlet (p,q)-equations

2020

We consider a nonlinear elliptic Dirichlet problem driven by the (p,q)-Laplacian and a reaction consisting of a parametric singular term plus a Caratheodory perturbation f(z,x) which is (p-1)-linear as x goes to + infinity. First we prove a bifurcation-type theorem describing in an exact way the changes in the set of positive solutions as the parameter lambda>0 moves. Subsequently, we focus on the solution multifunction and prove its continuity properties. Finally we prove the existence of a smallest (minimal) solution u*_lambda and investigate the monotonicity and continuity properties of the map lambda --> u*_lambda.

On a mixed boundary value problem involving the p-Laplacian

2011

In this paper we prove the existence of infinitely many solutions for a mixed boundary value problem involving the one dimensional p-Laplacian. A result on the existence of three solutions is also established. The approach is based on multiple critical points theorems.

Validation of models for sprays

2016

We consider complex fluids consisting of a dispersed phase (solid particles or liquid droplets) immersed in a gas. A class of models describing the dynamics of such a kind of systems is given by a system of partial differential equations where a kinetic equation, describing the dispersed phase, is coupled to a fluid equation for the background gas. The coupling is given by the drag force exerted by the gas on the dispersed phase. Within this class, we shall analyse the case where the kinetic equation is a Vlasov-type equation and the fluid equation are of Stokes or Navier-Stokes type. We shall discuss the validation problem for this class of models, i.e. the derivation of the equations of t…

Recensione a A. Ferrarin, "Galilei e la matematica della natura"

2015

A review of A. Ferrarin's last book about Galilei's relevance for the modern notion of science and methodology, with a particular attention to the issue of imagination as crucial for the develoment of scientific attitude.

Viscosity solutions of the Monge-Ampère equation with the right hand side in Lp

2007

We compare various notions of solutions of Monge-Ampère equations with discontinuous functions on the right hand side. Precisely, we show that the weak solutions defined by Trudinger can be obtained by the vanishing viscosity approximation method. Moreover, we investigate existence and uniqueness of Lp-viscosity solutions.

L'incertezza inSegna

2015

Traendo spunto dalla manifestazione scientifica Esperienza inSegna, dal titolo Certo è. . . probabile, svoltasi a Palermo nel 2014, in questo lavoro dapprima sono richiamati alcuni problemi che diedero la nascita al calcolo delle probabilità e successivamente vengono analizzati due problemi popolari di probabilità che normalmente sono oggetto di dibattito soprattutto tra i non addetti al settore: “Monty Hall” e il “Gratta e Vinci”. Nel primo si mostra l’importanza di tradurre correttamente, in termini di evento condizionante, l’informazione acquisita quando si vogliono “aggiornare” le probabilità; nel secondo si mette in guardia il lettore di fronte agli spot televisivi che annunciano vinci…

k-out-of-n systems: an exact formula for the stationary availability and multi-objective configuration design based on mathematical programming and T…

2018

[EN] Reliability and availability analyses are recognized as essential for guiding decision makers in the implementation of actions addressed to improve the technical and economical performance of complex systems. For industrial systems with reparable components, the most interesting parameter used to drive maintenance is the stationary availability. In this regard, the present paper proposes an exact formula for computing the system stationary availability of a k-out-of-n system. Such a formula is proved to be in agreement with the fundamental theorem of Markov chains. Then, a multi-objective mathematical model is formulated for choosing the optimal system configuration design. The Pareto …

Efficient High-Order Iterative Methods for Solving Nonlinear Systems and Their Application on Heat Conduction Problems

2017

[EN] For solving nonlinear systems of big size, such as those obtained by applying finite differences for approximating the solution of diffusion problem and heat conduction equations, three-step iterative methods with eighth-order local convergence are presented. The computational efficiency of the new methods is compared with those of some known ones, obtaining good conclusions, due to the particular structure of the iterative expression of the proposed methods. Numerical comparisons are made with the same existing methods, on standard nonlinear systems and a nonlinear one-dimensional heat conduction equation by transforming it in a nonlinear system by using finite differences. From these…

MR2858094 Musiał, Kazimierz Pettis integrability of multifunctions with values in arbitrary Banach spaces. J. Convex Anal. 18 (2011), no. 3, 769–810.…

2012

Traced tensor norms and multiple summing multilinear operators

2016

[EN] Using a general tensor norm approach, our aim is to show that some distinguished classes of summing operators can be characterized by means of an 'order reduction' procedure for multiple summing multilinear operators, which becomes the keystone of our arguments and can be considered our main result. We work in a tensor product framework involving traced tensor norms and the representation theorem for maximal operator ideals. Several applications are given not only to multi-ideals, but also to linear operator ideals. In particular, we get applications to multiple p-summing bilinear operators, (p, q)-factorable linear operators, tau(p)-summing linear operators and absolutely p-summing li…