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Irregularly sampled time series are increasingly prevalent, particularly in medical domains. While various specialized methods have been developed to handle these irregularities, effectively modeling their complex dynamics and pronounced…

Machine Learning · Computer Science 2023-11-01 Zekun Li , Shiyang Li , Xifeng Yan

The vertical slice transform takes a function on the n-dimensional unit sphere to integrals of that function over spherical slices parallel to the last coordinate axis. This transform arises in thermoacoustic tomography. We obtain new…

Functional Analysis · Mathematics 2018-07-23 Boris Rubin

As soon as Lyman or Balmer lines overlap, the net absorption cross section rapidly approaches the value at the series limit. Independent of the difficult question of the relative contributions of line and continuous opacity, we can get a…

Astrophysics · Physics 2007-05-23 Charles R. Cowley

An algorithm for sampling exactly from the normal distribution is given. The algorithm reads some number of uniformly distributed random digits in a given base and generates an initial portion of the representation of a normal deviate in…

Computational Physics · Physics 2016-02-01 Charles F. F. Karney

We prove that the focal set generated by the reflection of a point source off a translation invariant surface consists of two sets: a curve and a surface. The focal curve lies in the plane orthogonal to the symmetry direction containing the…

Differential Geometry · Mathematics 2021-11-15 Brendan Guilfoyle , Wilhelm Klingenberg

Giving a new form of the vortex mode equation by a proper change of parameter, our aim is to analyze the point and contact symmetries of the new equation. Fundamental invariants and a form of general solutions of point transformations along…

Differential Geometry · Mathematics 2011-12-30 Mehdi Nadjafikhah , Ali Mahdipour--Shirayeh

We study Variational Rectified Flow Matching, a framework that enhances classic rectified flow matching by modeling multi-modal velocity vector-fields. At inference time, classic rectified flow matching 'moves' samples from a source…

Machine Learning · Computer Science 2025-02-14 Pengsheng Guo , Alexander G. Schwing

This article considers the use of total variation minimization for the recovery of a superposition of point sources from samples of its Fourier transform along radial lines. We present a numerical algorithm for the computation of solutions…

Numerical Analysis · Mathematics 2017-06-06 Charles Dossal , Vincent Duval , Clarice Poon

Optimal sampling of non band-limited functions is an issue of great importance that has attracted considerable attention. We propose to tackle this problem through the use of a frequency warping: First, by a nonlinear shrinking of…

Classical Analysis and ODEs · Mathematics 2017-03-07 Stefan Lafon , Jacques Lévy Véhel , Jacques Peyrière

We develop a sampling scheme on the sphere that permits accurate computation of the spherical harmonic transform and its inverse for signals band-limited at $L$ using only $L^2$ samples. We obtain the optimal number of samples given by the…

Information Theory · Computer Science 2014-07-25 Zubair Khalid , Rodney A. Kennedy , Jason D. McEwen

It is shown here that precision is gained by analyzing the interferometric spectra directly from the interferograms, with no previous Fourier transformation to put them in the standard frequency domain. The method is based on the…

Instrumentation and Detectors · Physics 2018-04-20 Miguel Lagos , Rodrigo Paredes , Cesar Retamal

We study the symmetry resolved entanglement entropies in gapped integrable lattice models. We use the corner transfer matrix to investigate two prototypical gapped systems with a U(1) symmetry: the complex harmonic chain and the XXZ…

Statistical Mechanics · Physics 2020-03-27 Sara Murciano , Giuseppe Di Giulio , Pasquale Calabrese

We continue the study of the center problem for the ordinary differential equation $v'=\sum_{i=1}^{\infty}a_{i}(x)v^{i+1}$ started in our earlier papers. In this paper we present the highlights of the algebraic theory of centers.

Dynamical Systems · Mathematics 2007-05-23 Alexander Brudnyi

A new scheme to sample signals defined in the nodes of a graph is proposed. The underlying assumption is that such signals admit a sparse representation in a frequency domain related to the structure of the graph, which is captured by the…

Social and Information Networks · Computer Science 2016-04-20 Antonio G. Marques , Santiago Segarra , Geert Leus , Alejandro Ribeiro

The Marchenko method retrieves the responses to virtual sources in the subsurface, accounting for all orders of multiples. The method is based on two integral representations for focusing and Green's functions. In discretized form these…

Geophysics · Physics 2020-03-25 Johno van IJsseldijk , Kees Wapenaar

Given a Fourier transformable measure in two dimensions, we find a formula for the intensity of its Fourier transform along circles. In particular, we obtain a formula for the diffraction measure along a circle in terms of the…

Classical Analysis and ODEs · Mathematics 2024-05-15 Emily R. Korfanty , Nicolae Strungaru

We introduce a symmetrization technique that allows us to translate a problem of controlling the deviation of some functionals on a product space from their mean into a problem of controlling the deviation between two independent copies of…

Probability · Mathematics 2007-05-23 Dmitry Panchenko

Vertex based and spectral based GSP sampling has been studied recently. The literature recognizes that methods in one domain do not have a counterpart in the other domain. This paper shows that in fact one can develop a unified graph signal…

Signal Processing · Electrical Eng. & Systems 2022-06-29 John Shi , Jose M. F. Moura

A cornerstone of geometric reconstruction, rotation averaging seeks the set of absolute rotations that optimally explains a set of measured relative orientations between them. In addition to being an integral part of bundle adjustment and…

Computer Vision and Pattern Recognition · Computer Science 2024-06-28 Gabriel Moreira , Manuel Marques , João Paulo Costeira

In this short note, we present a flux-correction form of the third-order edge-based scheme for the Euler equations that enables the direct use of a general flux function. The core idea is to replace, without loss of accuracy, the arithmetic…

Numerical Analysis · Mathematics 2026-03-19 Hiroaki Nishikawa