85 research outputs found
Scalable numerical approach for the steady-state ab initio laser theory
We present an efficient and flexible method for solving the non-linear lasing
equations of the steady-state ab initio laser theory. Our strategy is to solve
the underlying system of partial differential equations directly, without the
need of setting up a parametrized basis of constant flux states. We validate
this approach in one-dimensional as well as in cylindrical systems, and
demonstrate its scalability to full-vector three-dimensional calculations in
photonic-crystal slabs. Our method paves the way for efficient and accurate
simulations of lasing structures which were previously inaccessible.Comment: 17 pages, 8 figure
Heat flow and calculus on metric measure spaces with Ricci curvature bounded below - the compact case
We provide a quick overview of various calculus tools and of the main results
concerning the heat flow on compact metric measure spaces, with applications to
spaces with lower Ricci curvature bounds.
Topics include the Hopf-Lax semigroup and the Hamilton-Jacobi equation in
metric spaces, a new approach to differentiation and to the theory of Sobolev
spaces over metric measure spaces, the equivalence of the L^2-gradient flow of
a suitably defined "Dirichlet energy" and the Wasserstein gradient flow of the
relative entropy functional, a metric version of Brenier's Theorem, and a new
(stronger) definition of Ricci curvature bound from below for metric measure
spaces. This new notion is stable w.r.t. measured Gromov-Hausdorff convergence
and it is strictly connected with the linearity of the heat flow.Comment: To the memory of Enrico Magenes, whose exemplar life, research and
teaching shaped generations of mathematician
New a posteriori error estimates for hp version of finite element methods of nonlinear parabolic optimal control problems
Generalized reduced basis methods and n-width estimates for the approximation of the solution manifold of parametric PDEs
The set of solutions of a parameter-dependent linear partial differential equation with smooth coefficients typically forms a compact manifold in a Hilbert space. In this paper we review the generalized reduced basis method as a fast computational tool for the uniform approximation of the solution manifold. We focus on operators showing an affine parametric dependence, expressed as a linear combination of parameter-independent operators through some smooth, parameter-dependent scalar functions. In the case that the parameter-dependent operator has a dominant term in its affine expansion, one can prove the existence of exponentially convergent uniform approximation spaces for the entire solution manifold. These spaces can be constructed without any assumptions on the parametric regularity of the manifold -- only spatial regularity of the solutions is required. The exponential convergence rate is then inherited by the generalized reduced basis method. We provide a numerical example related to parametrized elliptic equations confirming the predicted convergence rate
Finite Element Methods for Elliptic Distributed Optimal Control Problems with Pointwise State Constraints
Finite element methods for a model elliptic distributed optimal control
problem with pointwise state constraints are considered from the perspective of
fourth order boundary value problems
Comparative Analysis of Ck- and C0-GFEM Applied to Two-dimensional Problems of Confined Plasticity
Tensile Behaviour of a Structural Adhesive at High Temperatures by the eXtended Finite Element Method
Linear elastic fracture simulation directly from CAD: 2D NURBS-based implementation and role of tip enrichment
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