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Displaying 261 –
280 of
280
In this paper, we study
the linear Schrödinger equation over the d-dimensional torus,
with small values of the perturbing potential.
We consider numerical approximations of the associated solutions obtained
by a symplectic splitting method (to discretize the time variable) in combination with the
Fast Fourier Transform algorithm (to discretize the space variable).
In this fully discrete setting, we prove that the regularity of the initial
datum is preserved over long times, i.e. times that are...
Proper orthogonal decomposition (POD) is a
powerful technique for model reduction of non-linear systems. It
is based on a Galerkin type discretization with basis elements
created from the dynamical system itself. In the context of
optimal control this approach may suffer from the fact that the
basis elements are computed from a reference trajectory containing
features which are quite different from those of the optimally
controlled trajectory. A method is proposed which avoids this
problem of unmodelled...
In this paper we propose a new concept of quasi-uniform monotonicity weaker than the uniform monotonicity which has been developed in the study of nonlinear operator equation $Au=b$. We prove that if $A$ is a quasi-uniformly monotone and hemi-continuous operator, then $A^{-1}$ is strictly monotone, bounded and continuous, and thus the Galerkin approximations converge. Also we show an application of a quasi-uniformly monotone and hemi-continuous operator to the proof of the well-posedness and convergence...
In this paper, properties of projection and penalty methods are studied in connection with control problems and their discretizations. In particular, the convergence of an interior-exterior penalty method applied to simple state constraints as well as the contraction behavior of projection mappings are analyzed. In this study, the focus is on the application of these methods to discretized control problem.
The Longest-Edge (LE) bisection of a triangle is obtained by joining the midpoint of its longest edge with the opposite vertex. Here two properties of the longest-edge bisection scheme for triangles are proved. For any triangle, the number of distinct triangles (up to similarity) generated by longest-edge bisection is finite. In addition, if LE-bisection is iteratively applied to an initial triangle, then minimum angle of the resulting triangles is greater or equal than a half of the minimum angle...
We present a weak parametrix of the operator of the CFIE equation. An interesting feature of this parametrix is that it is compatible with different discretization strategies and hence allows for the construction of efficient preconditioners dedicated to the CFIE. Furthermore, one shows that the underlying operator of the CFIE verifies an uniform discrete Inf-Sup condition which allows to predict an original convergence result of the numerical solution of the CFIE to the exact one.
On exhibe dans cette note une paramétrix (au sens faible) de l'opérateur
sous-jacent à l'équation CFIE de l'électromagnétisme. L'intérêt de cette
paramétrix est de se prêter à différentes stratégies de discrétisation
et ainsi de pouvoir être utilisée comme préconditionneur de la CFIE.
On montre aussi que l'opérateur sous-jacent à la CFIE satisfait une condition
Inf-Sup discrète uniforme, applicable aux espaces de discrétisation usuellement rencontrés
en électromagnétisme, et qui permet d'établir...
In this paper new methods for solving elliptic variational inequalities with weakly coercive operators are considered. The use of the iterative prox-regularization coupled with a successive discretization of the variational inequality by means of a finite element method ensures well-posedness of the auxiliary problems and strong convergence of their approximate solutions to a solution of the original problem. In particular, regularization on the kernel of the differential operator and regularization...
Psi-series (i.e., logarithmic series) for the solutions of quadratic vector fields on the plane are considered. Its existence and convergence is studied, and an algorithm for the location of logarithmic singularities is developed. Moreover, the relationship between psi-series and non-integrability is stressed and in particular it is proved that quadratic systems with psi-series that are not Laurent series do not have an algebraic first integral. Besides, a criterion about non-existence of an analytic...
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