Search results for "auch"

Exact treatment of operator difference equations with nonconstant and noncommutative coefficients

2013

We study a homogeneous linear second-order difference equation with nonconstant and noncommuting operator coefficients in a vector space. We build its exact resolutive formula consisting of the explicit noniterative expression of a generic term of the unknown sequence of vectors. Some nontrivial applications are reported in order to show the usefulness and the broad applicability of the result.

Fully reliable a posteriori error control for evolutionary problems

2015

Existence and Regularity for a Class of Nonlinear Hyperbolic Boundary Value Problems

2002

AbstractThe regularity of the solution of the telegraph system with nonlinear monotone boundary conditions is investigated by two methods. The first one is based on D'Alembert-type representation formulae for the solution. In the second method the telegraph system is reduced to a linear Cauchy problem with a locally Lipschitzian functional perturbation; then regularity results are established by appealing to the theory of linear semigroups.

A note on the higher order strain and stress tensors within deformation gradient elasticity theories: Physical interpretations and comparisons

2016

Abstract Higher order strain and stress tensors encompassed within gradient elasticity theories are discussed with a particular concern to the physical meaning of double and triple stresses. A single rule is shown to hold for the physical interpretation of the indices of a higher order stress tensor both within distortion gradient and strain gradient theories, whereas the analogous Mindlin’s rule holds only within distortion gradient theories. Double and triple stresses are discussed separately with the aid of simple illustrative examples. A corrigendum to a previous paper by the author (IJSS 50 (2013) 3749–3765) is also presented.

A shallow water model with eddy viscosity for basins with varying bottom topography

2001

The motion of an incompressible fluid confined to a shallow basin with a varying bottom topography is considered. We introduce appropriate scalings into a three-dimensional anisotropic eddy viscosity model to derive a two-dimensional shallow water model. The global regularity of the resulting model is proved. The anisotropic form of the stress tensor in our three-dimensional eddy viscosity model plays a critical role in ensuring that the resulting shallow water model dissipates energy.

A nonhomogeneous nonlocal elasticity model

2006

Nonlocal elasticity with nonhomogeneous elastic moduli and internal length is addressed within a thermodynamic framework suitable to cope with continuum nonlocality. The Clausius–Duhem inequality, enriched by the energy residual, is used to derive the state equations and all other thermodynamic restrictions upon the constitutive equations. A phenomenological nonhomogeneous nonlocal (strain difference-dependent) elasticity model is proposed, in which the stress is the sum of two contributions, local and nonlocal, respectively governed by the standard elastic moduli tensor and the (symmetric positive-definite) nonlocal stiffness tensor. The inhomogeneities of the elastic moduli and of the int…

Quasilinear degenerate parabolic equations in unbounded domains

2004

We prove the existence of bounded solutions of Cauchy-Dirichlet problem associated to a degenerate parabolic equation of second order in divergence form in unbounded domain.

The principles of bioethics and the growth of an intercultural bioethics

2010

En este trabajo defiendo que el debate internacional sobre los principios de la bioética es uno de los más fructíferos para construir los fundamentos de una bioética intercultural. Tras recordar en qué consisten los principios de la bioética, tal y como han sido defendidos por Tom L. Beauchamp y James F. Childress en Estados Unidos, ofrezco una breve mirada a estos principios desde Europa, América Latina, África y Asia. Continúo con una reflexión sobre dichos principios desde algunas de las grandes religiones del mundo. Todo ello me permite ofrecer importantes elementos para construir las bases de lo que podríamos llamar una «bioética intercultural». In this article, I defend that the inter…

Parabolic-Lorentzian modified Gaussian model for describing and deconvolving chromatographic peaks.

2002

Abstract A new mathematical model for characterising skewed chromatographic peaks, which improves the previously reported polynomially modified Gaussian (PMG) model, is proposed. The model is a Gaussian based equation whose variance is a combined parabolic-Lorentzian function. The parabola accounts for the non-Gaussian shaped peak, whereas the Lorentzian function cancels the variance growth out of the elution region, which gives rise to a problematic baseline increase in the PMG model. The proposed parabolic-Lorentzian modified Gaussian (PLMG) model makes a correct description of peaks showing a wide range of asymmetry with positive and/or negative skewness. The new model is shown to give b…

New approaches based on modified Gaussian models for the prediction of chromatographic peaks

2012

Abstract The description of skewed chromatographic peaks has been discussed extensively and many functions have been proposed. Among these, the Polynomially Modified Gaussian (PMG) models interpret the deviations from ideality as a change in the standard deviation with time. This approach has shown a high accuracy in the fitting to tailing and fronting peaks. However, it has the drawback of the uncontrolled growth of the predicted signal outside the elution region, which departs from the experimental baseline. To solve this problem, the Parabolic-Lorentzian Modified Gaussian (PLMG) model was developed. This combines a parabola that describes the variance change in the peak region, and a Lor…