University of Catania

About: University of Catania is a education organization based out in Catania, Italy. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 14599 authors who have published 41195 publications receiving 1032705 citations. The organization is also known as: Università degli Studi di Catania & Universita degli Studi di Catania.

Modeling and Simulation of Induction Motors with Saturable Leakage Reactances

Abstract: A new method for the transient analysis of induction machines with saturating leakage reactances is presented. The equations which define operation under this condition are arranged so that the saturation of stator and rotor leakage as well as magnetizing reactance can be readily modeled with three function generators. The method is equally applicable to the analysis of synchronous machines.

Implicit-Explicit Runge-Kutta schemes for hyperbolic systems and kinetic equations in the diffusion limit

Abstract: We consider implicit-explicit (IMEX) Runge--Kutta (R-K) schemes for hyperbolic systems with stiff relaxation in the so-called diffusion limit. In such a regime the system relaxes towards a convection-diffusion equation. The first objective of this paper is to show that traditional partitioned IMEX R-K schemes will relax to an explicit scheme for the limit equation with no need of modification of the original system. Of course the explicit scheme obtained in the limit suffers from the classical parabolic stability restriction on the time step. The main goal of this paper is to present an approach, based on IMEX R-K schemes, that in the diffusion limit relaxes to an IMEX R-K scheme for the convection-diffusion equation, in which the diffusion is treated implicitly. This is achieved by a novel reformulation of the problem, and subsequent application of IMEX R-K schemes to it. An analysis of such schemes to the reformulated problem shows that the schemes reduce to IMEX R-K schemes for the limit equation, unde...

Design of chromophoric molecular assemblies with large second-order optical nonlinearities. A theoretical analysis of the role of intermolecular interactions

Abstract: The role and nature of intermolecular interactions in determining quadratic nonlinear optical macroscopic hyperpolarizabilities are investaged using the INDO/S (ZINDO) sum-over excited particle-hole-states formalism on clusters (dimers and trimers) of archetypical donor/acceptor organic π-electron chromophore molecules. It is found that the calculated aggregate hyperpolarizability depends strongly on relative molecular orientations, exhibiting the largest values in slipped cofacial arrangements, where the donor substituent of one molecular unit is in close spatial proximity to the acceptor subsituent of the nearest neighbor

Measurement error in geometric morphometrics

Abstract: Geometric morphometrics—a set of methods for the statistical analysis of shape once saluted as a revolutionary advancement in the analysis of morphology —is now mature and routinely used in ecology and evolution. However, a factor often disregarded in empirical studies is the presence and the extent of measurement error. This is potentially a very serious issue because random measurement error can inflate the amount of variance and, since many statistical analyses are based on the amount of “explained” relative to “residual” variance, can result in loss of statistical power. On the other hand, systematic bias can affect statistical analyses by biasing the results (i.e. variation due to bias is incorporated in the analysis and treated as biologically-meaningful variation). Here, I briefly review common sources of error in geometric morphometrics. I then review the most commonly used methods to measure and account for both random and non-random measurement error, providing a worked example using a real dataset.