Search results for "matematica"

Finite groups with all minimal subgroups solitary

2016

We give a complete classification of the finite groups with a unique subgroup of order p for each prime p dividing its order. All the groups considered in this paper will be finite. One of the most fruitful lines in the research in abstract group theory during the last years has been the study of groups in which the members of a certain family of subgroups satisfy a certain subgroup embedding property. The family of the subgroups of prime order (also called minimal subgroups) has attracted the interest of many mathematicians. For example, a well-known result of Itˆo (see [8, Kapitel III, Satz 5.3; 9]) states that a group of odd order with all minimal subgroups in the center is nilpotent. Th…

A note on *-derivations of partial *-algebras

2012

A definition of *-derivation of partial *-algebra through a sufficient family of ips-forms is proposed.

Monotone generalized nonlinear contractions and fixed point theorems in ordered metric spaces

2011

The purpose of this paper is to present some fixed point theorems for T -weakly isotone increasing mappings which satisfy a generalized nonlinear contractive condition in complete ordered metric spaces. As application, we establish an existence theorem for a solution of some integral equations.

FORMAZIONE DI PATTERN PER IL PROCESSO DELL'ELETTRODEPOSIZIONE IN MODELLI DI TIPO REAZIONE-DIFFUSIONE

2014

Permutations of zero-sumsets in a finite vector space

2020

Abstract In this paper, we consider a finite-dimensional vector space 𝒫 {{\mathcal{P}}} over the Galois field GF ⁡ ( p ) {\operatorname{GF}(p)} , with p being an odd prime, and the family ℬ k x {{\mathcal{B}}_{k}^{x}} of all k-sets of elements of 𝒫 {\mathcal{P}} summing up to a given element x. The main result of the paper is the characterization, for x = 0 {x=0} , of the permutations of 𝒫 {\mathcal{P}} inducing permutations of ℬ k 0 {{\mathcal{B}}_{k}^{0}} as the invertible linear mappings of the vector space 𝒫 {\mathcal{P}} if p does not divide k, and as the invertible affinities of the affine space 𝒫 {\mathcal{P}} if p divides k. The same question is answered also in the case where …

Dependence of effective properties upon regular perturbations

2022

In this survey, we present some results on the behavior of effective properties in presence of perturbations of the geometric and physical parameters. We first consider the case of a Newtonian fluid flowing at low Reynolds numbers around a periodic array of cylinders. We show the results of [43], where it is proven that the average longitudinal flow depends real analytically upon perturbations of the periodicity structure and the cross section of the cylinders. Next, we turn to the effective conductivity of a periodic two-phase composite with ideal contact at the interface. The composite is obtained by introducing a periodic set of inclusions into an infinite homogeneous matrix made of a di…

PLS...su e giù per l'Italia

2012

Improved pairwise comparison transitivity using strategically selected reduced information

2021

To judge the mutual relationship among elements, pairwise comparisons (PC) are widely used in decision modelling. PC is especially useful when the involved elements are intangible. Frequently, the number of elements to be compared may be very large. When dealing with n elements, the number of PCs is, under the reciprocity hypothesis, n(n − 1)/2. PCs are compiled in so-called pairwise comparison matrices (PCM). In the presence of missing entries due to uncertainty or lack of information, decision-making must be performed from the available incomplete information. Making all the comparisons in the complete case may be tedious, strenuous and time-consuming for the actors, may blur the body of …

Thermal Energy Density Driven Magnetic Reconnection

Magnetic reconnection is usually associated with conversion of magnetic energy into particle acceleration or thermal energy. However, a specific reconnection process driven by plasma pressure gradients was identified in Ref.[1] with a consistent theory of (non-ideal) MHD m0=1 modes in well confined plasmas. This process, based on an Ohm's law contribution to the electron balance equations, remains the basis for the explanation of the observed sawtooth oscillations of the central plasma pressure and for the inferred magnetic field structures due to fishbone oscillations associated with injected high energy particle populations. A novel process [2] expected to have a wide range of application…

Non-Thermal Fusion Burning Plasma Regimes

The Ignitor project is aimed at approaching ignition conditions in Deuterium-Tritium plasmas in order to investigate the issues related to the kind of characteristics of these plasmas, following the line of compact high field opened with the Alcator and Frascati Torus programs, which were capable of producing high density plasma regimes with record confinement properties combined with high degrees of plasma purity. We present a theoretical model describing the emergence of tridimensional structures in magnetically confined plasmas which can significantly change the conditions under which meaningful fusion burn conditions can be reached. These structures can be said to consist of "captive ba…