Unique continuation property and Poincar\'e inequality for higher order fractional Laplacians with applications in inverse problems

G Covi, K Mönkkönen, J Railo - arxiv preprint arxiv:2001.06210, 2020 - arxiv.org
We prove a unique continuation property for the fractional Laplacian $(-\Delta)^ s $ when $
s\in (-n/2,\infty)\setminus\mathbb {Z} $. In addition, we study Poincar\'e-type inequalities for …

Broken ray transform for twisted geodesics on surfaces with a reflecting obstacle

SR Jathar, M Kar, J Railo - The Journal of Geometric Analysis, 2024 - Springer
We prove a uniqueness result for the broken ray transform acting on the sums of functions
and 1-forms on surfaces in the presence of an external force and a reflecting obstacle. We …

Efficient tensor tomography in fan-beam coordinates

F Monard - arxiv preprint arxiv:1510.05132, 2015 - arxiv.org
We propose a thorough analysis of the tensor tomography problem on the Euclidean unit
disk parameterized in fan-beam coordinates. This includes, for the inversion of the Radon …

Abel transforms with low regularity with applications to x-ray tomography on spherically symmetric manifolds

MV de Hoop, J Ilmavirta - arxiv preprint arxiv:1702.07625, 2017 - arxiv.org
We study ray transforms on spherically symmetric manifolds with a piecewise $ C^{1, 1} $
metric. Assuming the Herglotz condition, the X-ray transform is injective on the space of $ L …

Broken ray transform on a Riemann surface with a convex obstacle

J Ilmavirta, M Salo - arxiv preprint arxiv:1403.5131, 2014 - arxiv.org
We consider the broken ray transform on Riemann surfaces in the presence of an obstacle,
following earlier work of Mukhometov. If the surface has nonpositive curvature and the …

X-ray transforms in pseudo-Riemannian geometry

J Ilmavirta - The Journal of Geometric Analysis, 2018 - Springer
We study the problem of recovering a function on a pseudo-Riemannian manifold from its
integrals over all null geodesics in three geometries: pseudo-Riemannian products of …

Torus computed tomography

J Ilmavirta, O Koskela, J Railo - SIAM Journal on Applied Mathematics, 2020 - SIAM
We present a new computed tomography (CT) method for inverting the Radon transform in 2
dimensions. The idea relies on the geometry of the flat torus; hence we call the new method …

A reflection approach to the broken ray transform

J Ilmavirta - Mathematica Scandinavica, 2015 - JSTOR
We reduce the broken ray transform on some Riemannian manifolds (with corners) to the
geodesic ray transform on another manifold, which is obtained from the original one by …

A range characterization of the single-quadrant ADRT

W Li, K Ren, D Rim - Mathematics of Computation, 2023 - ams.org
This work characterizes the range of the single-quadrant approximate discrete Radon
transform (ADRT) of square images. The characterization follows from a set of linear …

Determination of compactly supported functions in shift-invariant space by single-angle Radon samples

Y Li, S Fan, D Han - Journal of Functional Analysis, 2023 - Elsevier
While traditionally the computerized tomography of a function f∈ L 2 (R 2) depends on the
samples of its Radon transform at multiple angles, the real-time imaging sometimes requires …