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In tomographic reconstruction, the goal is to reconstruct an unknown object from a collection of line integrals. Given a complete sampling of such line integrals for various angles and directions, explicit inverse formulas exist to…

Numerical Analysis · Mathematics 2018-01-18 Tristan van Leeuwen , Simon Maretzke , K. Joost Batenburg

We consider the following geometric optics problem: Construct a system of two reflectors which transforms a spherical wavefront generated by a point source into a beam of parallel rays. This beam has a prescribed intensity distribution. We…

Analysis of PDEs · Mathematics 2015-05-13 Tilmann Glimm

Model sets (also called cut and project sets) are generalizations of lattices. Here we show how the self-similarities of model sets are a natural replacement for the group of translations of a lattice. This leads us to the concept of…

Mathematical Physics · Physics 2007-05-23 Michael Baake , Robert V. Moody

Homotopy is an important feature of associative and Jordan algebraic structures: such structures always come in families whose members need not be isomorphic among other, but still share many important properties. One may regard homotopy as…

Rings and Algebras · Mathematics 2007-05-23 Wolfgang Bertram

The correct insertion of virtual objects in images of real-world scenes requires a deep understanding of the scene's lighting, geometry and materials, as well as the image formation process. While recent large-scale diffusion models have…

Computer Vision and Pattern Recognition · Computer Science 2024-08-20 Ruofan Liang , Zan Gojcic , Merlin Nimier-David , David Acuna , Nandita Vijaykumar , Sanja Fidler , Zian Wang

The area of inverse problems in mathematics is highly interdisciplinary. In various fields of science, engineering, medicine, and industry, there arises a need to reconstruct information about unknown entities that cannot be directly…

Numerical Analysis · Mathematics 2024-09-17 Manabu Machida

We discuss how the diffraction theory of a single translation bounded measure or a family of such measures can be understood within the framework of unitary group representations. This allows us to prove an orthogonality feature of measures…

Functional Analysis · Mathematics 2024-02-05 Daniel Lenz , Nicolae Strungaru

We propose an algorithm to detect approximate reflection symmetry present in a set of volumetrically distributed points belonging to $\mathbb{R}^d$ containing a distorted reflection symmetry pattern. We pose the problem of detecting…

Computer Vision and Pattern Recognition · Computer Science 2019-01-16 Rajendra Nagar , Shanmuganathan Raman

Symmetries impose structure on the Hilbert space of a quantum mechanical model. The mathematical units of this structure are the irreducible representations of symmetry groups and I consider how they function as conceptual units of…

Quantum Physics · Physics 2018-01-29 N. L. Harshman

We consider the homogenization for time-fractional diffusion equations in a periodic structure and we derive the homogenized time-fractional diffusion equation. Then we discuss the determination of the constant diffusion coefficient by…

Analysis of PDEs · Mathematics 2023-03-06 Atsushi Kawamoto , Manabu Machida , Masahiro Yamamoto

A uniqueness result in the inverse problem for an inhomogeneous hyperbolic system on a real vector bundle over a smooth compact manifold, based on energy measurements for improperly known sources, is established.

Analysis of PDEs · Mathematics 2011-11-10 Katsiaryna Krupchyk , Matti Lassas

This article is the first part of a two-fold study, the objective of which is the theoretical analysis and numerical investigation of new approximate corrector problems in the context of stochastic homogenization. We present here three new…

Numerical Analysis · Mathematics 2018-07-16 Eric Cancès , Virginie Ehrlacher , Frederic Legoll , Benjamin Stamm , Shuyang Xiang

Model sets (also called cut and project sets) are generalizations of lattices, and multi-component model sets are generalizations of lattices with colourings. In this paper, we study self-similarities of multi-component model sets. The main…

Mathematical Physics · Physics 2007-05-23 Michael Baake , Robert V. Moody

In information fusion, one is often confronted with the following problem: given a preexisting set of measurements about an unknown quantity, what new measurements should one collect in order to accomplish a given fusion task with optimal…

Functional Analysis · Mathematics 2015-05-28 Matthew Fickus , Dustin G. Mixon , Miriam J. Poteet

We consider a diffusion equation with highly oscillatory coefficients that admits a homogenized limit. As an alternative to standard corrector problems, we introduce here an embedded corrector problem, written as a diffusion equation in the…

Numerical Analysis · Mathematics 2014-12-22 Eric Cances , Virginie Ehrlacher , Frederic Legoll , Benjamin Stamm

Homology-based invariants can be used to characterize the geometry of datasets and thereby gain some understanding of the processes generating those datasets. In this work we investigate how the geometry of a dataset changes when it is…

Algebraic Topology · Mathematics 2022-03-17 Jens Agerberg , Wojciech Chacholski , Ryan Ramanujam

When estimating quantities and fields that are difficult to measure directly, such as the fluidity of ice, from point data sources, such as satellite altimetry, it is important to solve a numerical inverse problem that is formulated with…

Mathematical Software · Computer Science 2023-08-11 Reuben W. Nixon-Hill , Daniel Shapero , Colin J. Cotter , David A. Ham

With increasing energy the diamagnetic hydrogen atom undergoes a transition from regular to chaotic classical dynamics, and the closed orbits pass through various cascades of bifurcations. Closed orbit theory allows for the semiclassical…

Chaotic Dynamics · Physics 2007-05-23 T. Fabcic , J. Main , T. Bartsch , G. Wunner

We study inverse boundary problems for the advection diffusion equation on an admissible manifold, i.e. a compact Riemannian manifold with boundary of dimension $\ge 3$, which is conformally embedded in a product of the Euclidean real line…

Analysis of PDEs · Mathematics 2017-04-20 Katya Krupchyk , Gunther Uhlmann

We generalize the notion of an anomaly for a symmetry to a noninvertible symmetry enacted by surface operators using the framework of condensation in 2-categories. Given a multifusion 2-category, potentially with some additional levels of…

Category Theory · Mathematics 2023-04-03 Thibault D. Décoppet , Matthew Yu