Search results for "Matematica"

Multi-parameter analysis of the obstacle scattering problem

2022

Abstract We consider the acoustic field scattered by a bounded impenetrable obstacle and we study its dependence upon a certain set of parameters. As usual, the problem is modeled by an exterior Dirichlet problem for the Helmholtz equation Δu + k 2 u = 0. We show that the solution u and its far field pattern u ∞ depend real analytically on the shape of the obstacle, the wave number k, and the Dirichlet datum. We also prove a similar result for the corresponding Dirichlet-to-Neumann map.

Mesure invariante d'une equation integrale stochastique a coefficients periodiques et applications a un modele d'epidemiologie

2012

We consider a stochastic integral equation, whose coe cients are periodic in time. Under a suitable condition we prove the existence of an invariant mesure for this stochastic equation. This invariant mesure is constructed on a Banach space of continuous functions. We study also its application to an epidemiologic model of malaria, which concerns the infected population and the vector population.

Convergence theorems for the PU-integral

2000

From Particle Systems to Partial Differential Equations International Conference, Particle Systems and PDEs VI, VII and VIII, 2017-2019

2021

This book includes the joint proceedings of the International Conference on Particle Systems and PDEs VI, VII and VIII. Particle Systems and PDEs VI was held in Nice, France, in November/December 2017, Particle Systems and PDEs VII was held in Palermo, Italy, in November 2018, and Particle Systems and PDEs VIII was held in Lisbon, Portugal, in December 2019. Most of the papers are dealing with mathematical problems motivated by different applications in physics, engineering, economics, chemistry and biology. They illustrate methods and topics in the study of particle systems and PDEs and their relation. The book is recommended to probabilists, analysts and to those mathematicians in general…

A sharp estimate for Neumann eigenvalues of the Laplace-Beltrami operator for domains in a hemisphere

2018

Here, we prove an isoperimetric inequality for the harmonic mean of the first [Formula: see text] non-trivial Neumann eigenvalues of the Laplace–Beltrami operator for domains contained in a hemisphere of [Formula: see text].

Laboratorio di matematica in classe: due nuove macchine per problemi nel continuo e nel discreto

2013

In this work we will introduce two mathematical machines (originally invented by the authors) that can be useful in class during laboratorial activities. We decided to introduce them together because they appeared us complementary about the subtended contents, in fact one of them solves a discrete problem (diophantine equations) involving concepts as integers, divisibility, and in general discrete math, while the other machine (solving differential equations in a grapho-mechanical way) involves the complementary concepts of continuous math: curves, tangents, derivatives. In this paper we will just present the machines, deepening the ideas and the subtended mathematical contents, but we will…

Decision-Making Tools to Manage the Microbiology of Drinking Water Distribution Systems

2020

[EN] This paper uses a two-fold multi-criteria decision-making (MCDM) approach applied for the first time to the field of microbial management of drinking water distribution systems (DWDS). Specifically, the decision-making trial and evaluation laboratory (DEMATEL) was applied removing the need for reliance on expert judgement, and analysed interdependencies among water quality parameters and microbiological characteristics of DWDS composed of different pipe materials. In addition, the fuzzy technique for order preference by similarity to ideal solution (FTOPSIS) ranked the most common bacteria identified during trials in a DWDS according to their relative abundance while managing vagueness…

Exponentiating derivations of quasi∗-algebras: possible approaches and applications

2005

The problem of exponentiating derivations of quasi∗-algebras is considered in view of applying it to the determination of the time evolution of a physical system. The particular case where observables constitute a properCQ∗-algebra is analyzed.

MR3631681 Reviewed Nigsch, E. A.(A-WIENM) On a nonlinear Peetre's theorem in full Colombeau algebras. (English summary) Comment. Math. Univ. Carolin.…

2017

Colombeau algebras are defined as quotients of spaces containing the representatives of generalized functions given by smooth mappings: R:C∞(Ω,D(Ω))→C∞(Ω), where Ω is an open subset of Rn. In this paper the notion of locality defined by the author for a representative R of a nonlinear generalized function is characterized in such a way that the representative depends only on its ∞-jet. Finally, the author examines the possibility of defining a notion of order for the mapping R.

On a Robin (p,q)-equation with a logistic reaction

2019

We consider a nonlinear nonhomogeneous Robin equation driven by the sum of a \(p\)-Laplacian and of a \(q\)-Laplacian (\((p,q)\)-equation) plus an indefinite potential term and a parametric reaction of logistic type (superdiffusive case). We prove a bifurcation-type result describing the changes in the set of positive solutions as the parameter \(\lambda \gt 0\) varies. Also, we show that for every admissible parameter \(\lambda \gt 0\), the problem admits a smallest positive solution.