Search results for "Integra"

Spectral approach to the scattering map for the semi-classical defocusing Davey–Stewartson II equation

2019

International audience; The inverse scattering approach for the defocusing Davey–Stewartson II equation is given by a system of D-bar equations. We present a numerical approach to semi-classical D-bar problems for real analytic rapidly decreasing potentials. We treat the D-bar problem as a complex linear second order integral equation which is solved with discrete Fourier transforms complemented by a regularization of the singular parts by explicit analytic computation. The resulting algebraic equation is solved either by fixed point iterations or GMRES. Several examples for small values of the semi-classical parameter in the system are discussed.

Identification of small inhomogeneities: Asymptotic factorization

2007

We consider the boundary value problem of calculating the electrostatic potential for a homogeneous conductor containing finitely many small insulating inclusions. We give a new proof of the asymptotic expansion of the electrostatic potential in terms of the background potential, the location of the inhomogeneities and their geometry, as the size of the inhomogeneities tends to zero. Such asymptotic expansions have already been used to design direct (i.e. noniterative) reconstruction algorithms for the determination of the location of the small inclusions from electrostatic measurements on the boundary, e.g. MUSIC-type methods. Our derivation of the asymptotic formulas is based on integral …

Finite element analysis of varitional crimes for a quasilinear elliptic problem in 3D

2000

We examine a finite element approximation of a quasilinear boundary value elliptic problem in a three-dimensional bounded convex domain with a smooth boundary. The domain is approximated by a polyhedron and a numerical integration is taken into account. We apply linear tetrahedral finite elements and prove the convergence of approximate solutions on polyhedral domains in the $W^1_2$ -norm to the true solution without any additional regularity assumptions.

Vereinfachte Rekursionen zur Richardson-Extrapolation in Spezialf�llen

1975

Recursions are given for Richardson-extrapolation based on generalized asymptotic expansions for the solution of a finite algorithm depending upon a parameterh>0. In particular, these expansions may contain terms likeh ?·log(h), (?>0). Simplified formulae are established in special cases. They are applicable to numerical integration of functions with algebraic or logarithmic endpoint singularities and provide a Romberg-type quadrature.

Rational solutions to the KPI equation from particular polynomials

2022

Abstract We construct solutions to the Kadomtsev–Petviashvili equation (KPI) from particular polynomials. We obtain rational solutions written as a second spatial derivative of a logarithm of a determinant of order n . We obtain with this method an infinite hierarchy of rational solutions to the KPI equation. We give explicitly the expressions of these solutions for the first five orders.

Estimates for the constants of Landau and Lebesgue via some inequalities for the Wallis ratio

2014

Efficient boundary integral-resonant mode expansion method implementation for full-wave analysis of passive devices based on circular waveguides with…

2013

In this study, the efficient full-wave analysis of passive devices composed of circular and arbitrarily-shaped waveguides is considered. For this purpose, the well-known boundary integral-resonant mode expansion (BI RME) method has been properly extended. Circular waveguides are used for resonant mode expansion, whereas the arbitrary contour is defined by any combination of straight, circular and elliptical segments, thus allowing the exact representation of the most widely used geometries. The proposed algorithm extends previous implementations of the BI RME method based on circular waveguides by considering circular and elliptical arcs for defining arbitrary geometries. Similarly, it allo…

Information Integration Platform for Patient-Centric Healthcare Services: Design, Prototype and Dependability Aspects

2014

Published version of an article in the journal: Future Internet. Also available from the publisher at: http://dx.doi.org/10.3390/fi6010126 Open Access Technology innovations have pushed today’s healthcare sector to an unprecedented new level. Various portable and wearable medical and fitness devices are being sold in the consumer market to provide the self-empowerment of a healthier lifestyle to society. Many vendors provide additional cloud-based services for devices they manufacture, enabling the users to visualize, store and share the gathered information through the Internet. However, most of these services are integrated with the devices in a closed “silo” manner, where the devices can…

Fronteras por definir, descontento creciente, alianzas inestables y amenazas externas: la Unión Europea y su tormenta perfecta

2018

espanolLa Union Europea se halla en una crisis existencial tan evidente que incluso politicos y analistas con antecedentes ideologicos diametralmente opues-tos han acabado coincidiendo en su diagnostico, y en la necesidad urgente de una terapia de choque que detenga lo que parece una carrera hacia la destruccion del proyecto europeo. El proposito del presente ensayo es pasar revista —aun al precio de tener que ser extraordinariamente sintetico en su abordaje— a los problemas que han sumido a la Union Europea en la mas grave crisis de su ya larga historia. Problemas que en todo caso son susceptibles de agruparse en cuatro grandes rubros: los que han ralentizado y hasta invertido el proceso d…

Mobile Ontologies

2008

The number of mobile subscribers in the world is soon reaching the three billion mark. According to the newest estimates, majority of the subscribers are already in the developing countries, whereas the number of subscribers in the industrialized countries is about to stagnate around one billion. Because especially in the developing countries the only access to Internet are mobile devices, developing high quality services based on them grows in importance. Ontologies are an important ingredient towards more complicated mobile services and wider usage of mobile terminals. In this article, we first discuss ontology and epistemology concepts in general. After that, we review ontologies in the …