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The Dynamic Mode Decomposition (DMD)---a popular method for performing data-driven Koopman spectral analysis---has gained increased adoption as a technique for extracting dynamically meaningful spatio-temporal descriptions of fluid flows…

Fluid Dynamics · Physics 2017-07-13 Maziar S. Hemati , Clarence W. Rowley , Eric A. Deem , Louis N. Cattafesta

This paper describes the implementation of the direct solution method (DSM) using radial spectral elements for the calculation of synthetic seismograms in self-gravitating, spherically symmetric, non-rotating, anelastic, and transversely…

Geophysics · Physics 2026-03-10 Alex D. C. Myhill , David Al-Attar

This paper is concerned with the inverse acoustic scattering problems by an obstacle or a cavity with a sound-soft or a sound-hard boundary. A direct imaging method relying on the boundary conditions is proposed for reconstructing the shape…

Numerical Analysis · Mathematics 2022-02-21 Deyue Zhang , Yue Wu , Yinglin Wang , Yukun Guo

In image processing, solving inverse problems is the task of finding plausible reconstructions of an image that was corrupted by some (usually known) degradation operator. Commonly, this process is done using a generative image model that…

Image and Video Processing · Electrical Eng. & Systems 2025-08-22 Idan Achituve , Hai Victor Habi , Amir Rosenfeld , Arnon Netzer , Idit Diamant , Ethan Fetaya

This paper proposes using a method named Double Score Matching (DSM) to do mass-imputation and presents an application to make inferences with a nonprobability sample. DSM is a $k$-Nearest Neighbors algorithm that uses two balance scores…

Methodology · Statistics 2021-10-19 Ali Furkan Kalay

Recently, diffusion models have been used to solve various inverse problems in an unsupervised manner with appropriate modifications to the sampling process. However, the current solvers, which recursively apply a reverse diffusion step…

Machine Learning · Computer Science 2024-05-21 Hyungjin Chung , Byeongsu Sim , Dohoon Ryu , Jong Chul Ye

We apply MUltiple SIgnal Classification (MUSIC) algorithm for the location reconstruction of a set of {two-dimensional circle-like} small inhomogeneities in the limited-aperture inverse scattering problem. Compared with the full- or…

Numerical Analysis · Mathematics 2024-11-12 Won-Kwang Park

We consider the problem of determining the shape and location of an unknown penetrable object in a perfectly conducting electromagnetic waveguide. The inverse problem is posed in the frequency domain and uses multistatic data in the near…

Numerical Analysis · Mathematics 2019-09-04 Peter Monk , Virginia Selgas , Fan Yang

A version of the Dynamical Systems Method (DSM) for solving ill-posed nonlinear equations with monotone operators in a Hilbert space is studied in this paper. An a posteriori stopping rule, based on a discrepancy-type principle is proposed…

Numerical Analysis · Mathematics 2015-05-13 N. S. Hoang , A. G. Ramm

This work investigates the electrical impedance tomography (EIT) problem when only limited boundary measurements are available, which is known to be challenging due to the extreme ill-posedness. Based on the direct sampling method (DSM), we…

Numerical Analysis · Mathematics 2020-09-18 Ruchi Guo , Jiahua Jiang

In this paper, we present the Directly Denoising Diffusion Model (DDDM): a simple and generic approach for generating realistic images with few-step sampling, while multistep sampling is still preserved for better performance. DDDMs require…

Computer Vision and Pattern Recognition · Computer Science 2024-06-03 Dan Zhang , Jingjing Wang , Feng Luo

The statistical properties of the density map (DM) approach to counting microbiological objects on images are studied in detail. The DM is given by U$^2$-Net. Two statistical methods for deep neural networks are utilized: the bootstrap and…

Computer Vision and Pattern Recognition · Computer Science 2022-07-07 Krzysztof M. Graczyk , Jaroslaw Pawlowski , Sylwia Majchrowska , Tomasz Golan

This paper concerns an application of the orthogonality sampling method (OSM) for a real-time identification of small objects from two-dimensional Fresnel experimental dataset in transverse electric polarization. First, we apply the OSM…

Numerical Analysis · Mathematics 2025-04-28 Junyong Eom , Sangwoo Kang , Minyeob Lee , Won-Kwang Park

This paper addresses the inverse scattering problem for Maxwell's equations. We first show that a bianisotropic scatterer can be uniquely determined from multi-static far-field data through the factorization analysis of the far-field…

Numerical Analysis · Mathematics 2025-02-03 Thu Le , Dinh-Liem Nguyen

We focus on a class of non-smooth optimization problems over the Stiefel manifold in the decentralized setting, where a connected network of $n$ agents cooperatively minimize a finite-sum objective function with each component being weakly…

Optimization and Control · Mathematics 2023-04-03 Jinxin Wang , Jiang Hu , Shixiang Chen , Zengde Deng , Anthony Man-Cho So

We propose a novel image sampling method for differentiable image transformation in deep neural networks. The sampling schemes currently used in deep learning, such as Spatial Transformer Networks, rely on bilinear interpolation, which…

Computer Vision and Pattern Recognition · Computer Science 2019-09-11 Wei Jiang , Weiwei Sun , Andrea Tagliasacchi , Eduard Trulls , Kwang Moo Yi

Dynamic mode decomposition (DMD) is an emerging methodology that has recently attracted computational scientists working on nonintrusive reduced order modeling. One of the major strengths that DMD possesses is having ground theoretical…

Numerical Analysis · Mathematics 2022-01-12 Shady E. Ahmed , Omer San , Diana A. Bistrian , Ionel M. Navon

We revisit two basic Direct Simulation Monte Carlo Methods to model aggregation kinetics and extend them for aggregation processes with collisional fragmentation (shattering). We test the performance and accuracy of the extended methods and…

Numerical Analysis · Mathematics 2022-07-27 A. Kalinov , A. I. Osinsky , S. A. Matveev , W. Otieno , N. V. Brilliantov

In this paper, we consider an inverse electromagnetic medium scattering problem of reconstructing unknown objects from time-dependent boundary measurements. A novel time-domain direct sampling method is developed for determining the…

Numerical Analysis · Mathematics 2024-10-11 Chen Geng , Minghui Song , Xianchao Wang , Yuliang Wang

This paper is concerned with the inverse scattering problem by an unbounded rough surface. A direct imaging method is proposed to reconstruct the rough surface from the scattered near-field Cauchy data generating by point sources and…

Numerical Analysis · Mathematics 2018-05-01 Xiaoli Liu , Bo Zhang , Haiwen Zhang