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The interaction of neural networks with physical equations offers a wide range of applications. We provide a method which enables a neural network to transform objects subject to given physical constraints. Therefore an U-Net architecture…

Artificial Intelligence · Computer Science 2021-03-22 Lukas Harsch , Johannes Burgbacher , Stefan Riedelbauch

The diffuse interface model of Cahn-Hilliard-van der Waals is often used to study various aspects of multi-phase flows such as droplets coalescence and contact line dynamics. The original model of Cahn-Hilliard-van der Waals uses an…

Fluid Dynamics · Physics 2014-08-29 Lionel Hirschberg , Avraham Hirschberg

We analyze an approximation of a Laplacian subject to non-local interface conditions of a $\delta'$-type by Neumann Laplacians on a family of Riemannian manifolds with a sieve-like structure. We establish a (kind of) resolvent convergence…

Analysis of PDEs · Mathematics 2025-06-24 Pavel Exner , Andrii Khrabustovskyi

We are concerned with inverse boundary problems for first order perturbations of the Laplacian, which arise as model operators in the acoustic tomography of a moving fluid. We show that the knowledge of the Dirichlet--to--Neumann map on the…

Analysis of PDEs · Mathematics 2020-04-27 Boya Liu

We study numerical computation of conformal invariants of domains in the complex plane. In particular, we provide an algorithm for computing the conformal capacity of a condenser. The algorithm applies for wide kind of geometries: domains…

Complex Variables · Mathematics 2020-08-19 Mohamed M S Nasser , Matti Vuorinen

The question whether one can recover the shape of a geometric object from its Laplacian spectrum ('hear the shape of the drum') is a classical problem in spectral geometry with a broad range of implications and applications. While…

Computational Geometry · Computer Science 2020-09-09 Luca Cosmo , Mikhail Panine , Arianna Rampini , Maks Ovsjanikov , Michael M. Bronstein , Emanuele Rodolà

This paper defines a theory of conformal parametrization of digital surfaces made of surfels equipped with a normal vector. The main idea is to locally project each surfel to the tangent plane, therefore deforming its aspect-ratio. It is a…

Computational Geometry · Computer Science 2008-02-18 Christian Mercat

Natural image matting, which separates foreground from background, is a very important intermediate step in recent computer vision algorithms. However, it is severely underconstrained and difficult to solve. State-of-the-art approaches…

Computer Vision and Pattern Recognition · Computer Science 2014-04-16 Philip G. Lee , Ying Wu

We consider numerical solution of elliptic problems with heterogeneous diffusion coefficients containing thin highly conductive structures. Such problems arise e.g. in fractured porous media, reinforced materials, and electric circuits. The…

Numerical Analysis · Mathematics 2020-07-22 Fredrik Hellman , Axel Målqvist , Siyang Wang

Explicit harmonic and wave maps are typically available only in highly symmetric or constant-curvature settings, where additional symmetry or integrability structures are present. We develop a reduction framework for pseudo-Riemannian…

Differential Geometry · Mathematics 2026-05-28 Anestis Fotiadis , Giannis Polychrou

We adapt boundary deformation techniques to solve a Neumann problem for the Helmholtz equation with rough electric potentials in bounded domains. In particular, we study the dependance of Neumann eigenvalues of the perturbed Laplacian with…

Analysis of PDEs · Mathematics 2025-01-14 Manuel Cañizares

In the context of transition analysis, linear input-output analysis determines worst-case disturbances to a laminar base flow based on a generic right-hand-side volumetric/boundary forcing term. The worst-case forcing is not physically…

Fluid Dynamics · Physics 2023-02-15 Omar Kamal , Matthew T. Lakebrink , Tim Colonius

The thesis studies linear and semilinear Dirichlet problems driven by different fractional Laplacians. The boundary data can be smooth functions or also Radon measures. The goal is to classify the solutions which have a singularity on the…

Analysis of PDEs · Mathematics 2015-11-03 Nicola Abatangelo

The aim of this paper is to propose a novel framework to infer the sheaf Laplacian, including the topology of a graph and the restriction maps, from a set of data observed over the nodes of a graph. The proposed method is based on sheaf…

Signal Processing · Electrical Eng. & Systems 2025-02-03 Leonardo Di Nino , Sergio Barbarossa , Paolo Di Lorenzo

Boundary conforming coordinates are commonly used in plasma physics to describe the geometry of toroidal domains, for example, in three-dimensional magnetohydrodynamic equilibrium solvers. The magnetohydrodynamic equilibrium configuration…

Plasma Physics · Physics 2025-02-07 Robert Babin , Florian Hindenlang , Omar Maj , Robert Köberl

In this work, we introduce a novel method to render, in real-time, Lambertian surfaces with a rough dieletric coating. We show that the appearance of such configurations is faithfully represented with two microfacet lobes accounting for…

Graphics · Computer Science 2022-03-23 Héloïse de Dinechin , Laurent Belcour

We present an introduction to modern theories of interfacial fluctuations and the associated interfacial parameters: surface tension and surface stiffness, as well as their interpretation within the capillary wave model. Transfer matrix…

Condensed Matter · Physics 2014-10-13 Vladimir Privman

We study numerically the one-dimensional Allen-Cahn equation with the spectral fractional Laplacian $(-\Delta)^{\alpha/2}$ on intervals with homogeneous Neumann boundary conditions. In particular, we are interested in the speed of sharp…

Dynamical Systems · Mathematics 2024-07-25 Franz Achleitner , Christian Kuehn , Jens Markus Melenk , Alexander Rieder

We describe a generalized formalism, addressing the fundamental problem of reflection and transmission of complex optical waves at a plane dielectric interface. Our formalism involves the application of generalized operator matrices to the…

Optics · Physics 2023-02-28 Anirban Debnath , Nirmal K. Viswanathan

The boundary conditions at the deformable interface between two contacting fluids are derived for the general case of the large-amplitude perturbations. The interface is modeled as perturbed free boundary that evolves in time, and the…

Fluid Dynamics · Physics 2018-03-13 Ivan V. Kazachkov