arXiv subjects

J. P. Zubelli

Publications and source records attributed to J. P. Zubelli.

3 recordsLinked to original sources

arXiv2020

Inverse problems for semiconductors: models and methods

We consider the problem of identifying discontinuous doping profiles in semiconductor devices from data obtained by different models connected to the voltage-current map. Stationary as well as transient settings are discussed and a framework for the corresponding inverse problems is established. Numerical implementations for the so-called stationary unipolar and stationary bipolar cases show the effectiveness of a level set approach to tackle the inverse problem.

math.NA↗

arXiv2020

On inverse doping profile problems for the stationary voltage-current map

We consider the problem of identifying possibly discontinuous doping profiles in semiconductor devices from data obtained by\,stationary voltage-current maps. In particular, we focus on the so-called unipolar case, a system of PDE's derived directly from the drift diffusion equations. The related inverse problem corresponds to an inverse conductivity problem with partial data. The identification issue for this inverse problem is considered. In particular, for a discretized version of the problem, we derive a result connected to diffusion tomography theory. A numerical approach for the identification problem using level set methods is presented. Our method is compared with previous results in the literature, where Landweber-Kaczmarz type methods were used to solve a similar problem.

math.AP↗

arXiv2000

Geodesic Flows on Diffeomorphisms of the Circle, Grassmannians, and the Geometry of the Periodic KdV Equation

We start by constructing a Hilbert manifold T of orientation preserving diffeomorphisms of the circle (modulo the group of bi-holomorphic self-mappings of the disc). This space, which could be thought of as a completion of the universal Teichmueller space, is endowed with a right-invariant Kaehler metric. Using results from the theory of quasiconformal mappings we construct an embedding of T into the infinite dimensional Segal-Wilson Grassmannian. The latter turns out to be a very natural ambient space for T. This allows us to prove that T's sectional curvature is negative in the holomorphic directions and by a reasoning along the lines of Cartan-Hadamard's theory that its geodesics exist for all time. The geodesics of T lead to solutions of the periodic Korteweg-de Vries (KdV) equation by means of V. Arnold's generalization of Euler's equation. As an application, we obtain long-time existence of solutions to the periodic KdV equation with initial data in a certain closed subspace of the periodic Sobolev space of index 3/2.

math-ph↗