Search results for "approximation"
showing 10 items of 818 documents
Approximators and mitigators in Chilean Spanish: the case of 'como' and 'como que'
2019
espanolEn el presente trabajo se realiza un analisis del uso de los aproximadores como y como que en el espanol de Chile y la vinculacion de su valor semantico aproximador con la atenuacion pragmatica. Diversos son los trabajos que han otorgado al marcador como un valor aproximativo (Mihatsch, 2009, 2010; Jorgensen y Stenstrom 2009; Jorgensen, 2011; Holmvik, 2011; Kornfeld, 2013; Kern, 2014; Jimenez y Flores-Ferran, 2018) y tambien un valor atenuador (Briz, 1998; Jorgensen, 2011; Holmvik, 2011; Kornfeld, 2013, Panussis, 2016; Mondaca, 2017; Panussis y San Martin, 2017). Asi, el objetivo es analizar la relacion que existe entre la aproximacion semantica y la atenuacion pragmatica por medio d…
Functional Extrapolations to Tame Unbound Anions in Density-Functional Theory Calculations
2019
Standard flavors of density-functional theory (DFT) calculations are known to fail in describing anions, due to large self-interaction errors. The problem may be circumvented using localized basis sets of reduced size, leaving no variational flexibility for the extra electron to delocalize. Alternatively, a recent approach exploiting DFT evaluations of total energies on electronic densities optimized at the Hartree-Fock (HF) level has been reported, showing that the self-interaction-free HF densities are able to lead to an improved description of the additional electron, returning affinities in close agreement with the experiments. Nonetheless, such an approach can fail when the HF densitie…
On time-harmonic Maxwell equations with nonhomogeneous conductivities : Solvability and FE-approximation
1989
The solvability of time-harmonic Maxwell equations in the 3D-case with nonhomogeneous conductivities is considered by adapting Sobolev space technique and variational formulation of the probJem in question. Moreover, a finite element approximation is presented in the 3D·case together with an error estimate in the energy norm. Some remarks are given to the 2D-problem arising from geophysics. peerReviewed
Factor selection procedures in a Google Earthtm aided landslide susceptibility model: application to the Beiro river basin (Spain)
2011
A procedure to select the controlling factors connected to the slope instability has been defined. It allowed to assess the landslide susceptibility in the Rio Beiro basin (about 10 km2) over the north-eastern area of the city of Granada (Spain). Field and remote (Google EarthTM) recognition techniques allowed to generate a landslide inventory consisting in 127 phenomena. Univariate tests, using both association coefficients and validation results of single parameter susceptibility models, allowed to select among 15 controlling factors the ones that resulted as good predictor variables; these have been combined for unique conditions analysis and susceptibility maps were finally prepared. In…
Quasi-Fractional Models of Human Tendons Hereditariness
2018
In this study, the authors, after collecting a series of experimental evidences following a creep and relaxation tendon campaign, propose a non-linear model of the viscoelastic behavior of the tendons. The ligaments investigated are the patellars and the hamstrings. The analytical model proposed by the authors aims to explain the non-linear hereditary behavior of these tissues and proposes an approach with which to develop a hereditary fractional-order non-linear model.
Nuclear structure and neutrino-nucleus reactions at supernova energies
2015
Supernova-(anti-)neutrino–nucleus scattering is discussed with reference to neutral-current (NC) and charged-current (CC) processes in heavy stable nuclei. The Donnelly-Walecka method with the associated multipole expansion of the nucleonic current has been adopted as the basic framework in deriving the neutrino-nucleus scattering cross sections. The needed nuclear wave functions are computed by using the quasiparticle random-phase approximation (QRPA) for the even-even target nuclei in the NC processes and the proton-neutron QRPA (pnQRPA) has been used to compute the CC processes for the mentioned nuclei. The wave functions of the stable odd-mass target nuclei have been obtained by the use…
Recovering a variable exponent
2021
We consider an inverse problem of recovering the non-linearity in the one dimensional variable exponent $p(x)$-Laplace equation from the Dirichlet-to-Neumann map. The variable exponent can be recovered up to the natural obstruction of rearrangements. The main technique is using the properties of a moment problem after reducing the inverse problem to determining a function from its $L^p$-norms.
ISODECIMAL NUMBERS
2006
The aim of this paper is to investigate pairs of real numbers of the type $(x,\frac{1}{x}),$ \ $(x,\frac{a}{x})$ and $(x,x^{2}),$ where the first component is a real number $x\neq0$ and the fractional parts of the coordinates are equal. We call such numbers \textit{isodecimal}.
Quantitative Approximation Properties for the Fractional Heat Equation
2017
In this note we analyse \emph{quantitative} approximation properties of a certain class of \emph{nonlocal} equations: Viewing the fractional heat equation as a model problem, which involves both \emph{local} and \emph{nonlocal} pseudodifferential operators, we study quantitative approximation properties of solutions to it. First, relying on Runge type arguments, we give an alternative proof of certain \emph{qualitative} approximation results from \cite{DSV16}. Using propagation of smallness arguments, we then provide bounds on the \emph{cost} of approximate controllability and thus quantify the approximation properties of solutions to the fractional heat equation. Finally, we discuss genera…
The Calderón problem for the fractional wave equation: Uniqueness and optimal stability
2021
We study an inverse problem for the fractional wave equation with a potential by the measurement taking on arbitrary subsets of the exterior in the space-time domain. We are interested in the issues of uniqueness and stability estimate in the determination of the potential by the exterior Dirichlet-to-Neumann map. The main tools are the qualitative and quantitative unique continuation properties for the fractional Laplacian. For the stability, we also prove that the log type stability estimate is optimal. The log type estimate shows the striking difference between the inverse problems for the fractional and classical wave equations in the stability issue. The results hold for any spatial di…