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We study the problem of one-dimensional regression of data points with total-variation (TV) regularization (in the sense of measures) on the second derivative, which is known to promote piecewise-linear solutions with few knots. While there…

Optimization and Control · Mathematics 2021-12-22 Thomas Debarre , Quentin Denoyelle , Michael Unser , Julien Fageot

High-frequency issues have been remarkably challenges in numerical methods for partial differential equations. In this paper, a learning based numerical method (LbNM) is proposed for Helmholtz equation with high frequency. The main novelty…

Numerical Analysis · Mathematics 2024-01-18 Yu Chen , Jin Cheng , Tingyue Li , Yun Miao

Recovering a signal from its Fourier intensity underlies many important applications, including lensless imaging and imaging through scattering media. Conventional algorithms for retrieving the phase suffer when noise is present but display…

Image and Video Processing · Electrical Eng. & Systems 2020-03-05 Yaotian Wang , Xiaohang Sun , Jason W. Fleischer

A new method based on the phenomenon of synchronization and the properties of chaos is proposed to reduce interference in the transferred chaotic signals of synchronized systems. In this paper, the interference is considered as a series of…

Mathematical Physics · Physics 2011-09-27 Yang Nan , Long Zhang-Cai , Zhao Xiang-Hui

For the solution of full-rank ill-posed linear systems a new approach based on the Arnoldi algorithm is presented. Working with regularized systems, the method theoretically reconstructs the true solution by means of the computation of a…

Numerical Analysis · Mathematics 2010-09-29 Claude Brezinski , Paolo Novati , Michela Redivo-Zaglia

We present an extension of the linear sampling method for solving the sound-soft inverse acoustic scattering problem with randomly distributed point sources. The theoretical justification of our sampling method is based on the…

Numerical Analysis · Mathematics 2023-03-21 Josselin Garnier , Houssem Haddar , Hadrien Montanelli

This paper is concerned with the inverse problem of reconstructing an inhomogeneous medium from the acoustic far-field data at a fixed frequency in two dimensions. This inverse problem is severely ill-posed (and also strongly nonlinear),…

Numerical Analysis · Mathematics 2023-09-21 Kai Li , Bo Zhang , Haiwen Zhang

This work focuses on developing and motivating a stochastic version of a wellknown inverse problem methodology. Specifically, we consider the iteratively regularized Gauss-Newton method, originally proposed by Bakushinskii for…

Numerical Analysis · Mathematics 2024-09-20 El Houcine Bergou , Neil K. Chada , Youssef Diouane

The cross-entropy loss commonly used in deep learning is closely related to the defining properties of optimal representations, but does not enforce some of the key properties. We show that this can be solved by adding a regularization…

Machine Learning · Statistics 2017-02-14 Alessandro Achille , Stefano Soatto

Markov random fields are used to model high dimensional distributions in a number of applied areas. Much recent interest has been devoted to the reconstruction of the dependency structure from independent samples from the Markov random…

Computational Complexity · Computer Science 2010-03-09 Guy Bresler , Elchanan Mossel , Allan Sly

We consider a statistical inverse learning problem, where the task is to estimate a function $f$ based on noisy point evaluations of $Af$, where $A$ is a linear operator. The function $Af$ is evaluated at i.i.d. random design points $u_n$,…

Machine Learning · Statistics 2021-11-02 Tatiana A. Bubba , Martin Burger , Tapio Helin , Luca Ratti

In this paper, we discuss application of iterative Stochastic Optimization routines to the problem of sparse signal recovery from noisy observation. Using Stochastic Mirror Descent algorithm as a building block, we develop a multistage…

Machine Learning · Statistics 2022-03-31 Anatoli Juditsky , Andrei Kulunchakov , Hlib Tsyntseus

We consider the ill-posed inverse problem of identifying a nonlinearity in a time-dependent PDE model. The nonlinearity is approximated by a neural network, and needs to be determined alongside other unknown physical parameters and the…

Numerical Analysis · Mathematics 2022-11-23 Barbara Kaltenbacher , Tram Thi Ngoc Nguyen

We study the choice of the regularisation parameter for linear ill-posed problems in the presence of noise that is possibly unbounded but only finite in a weaker norm, and when the noise-level is unknown. For this task, we analyse several…

Numerical Analysis · Mathematics 2021-04-14 Stefan Kindermann , Kemal Raik

Image interpolation based on diffusion models is promising in creating fresh and interesting images. Advanced interpolation methods mainly focus on spherical linear interpolation, where images are encoded into the noise space and then…

Computer Vision and Pattern Recognition · Computer Science 2024-03-15 PengFei Zheng , Yonggang Zhang , Zhen Fang , Tongliang Liu , Defu Lian , Bo Han

The success of deep neural networks is mostly due their ability to learn meaningful features from the data. Features learned in the hidden layers of deep neural networks trained in computer vision tasks have been shown to be similar to…

Machine Learning · Computer Science 2017-01-04 Biswajit Paria , Vikas Reddy , Anirban Santara , Pabitra Mitra

In many applications of tomography, the acquired projections are either limited in number or contain a significant amount of noise. In these cases, standard reconstruction methods tend to produce artifacts that can make further analysis…

Numerical Analysis · Mathematics 2016-04-11 D. M. Pelt , K. J. Batenburg

Recent advances have demonstrated the possibility of solving the deconvolution problem without prior knowledge of the noise distribution. In this paper, we study the repeated measurements model, where information is derived from multiple…

Statistics Theory · Mathematics 2024-09-04 Jérémie Capitao-Miniconi , Elisabeth Gassiat , Luc Lehéricy

Toeplitz-structured linear systems arise often in practical engineering problems. Correspondingly, a number of algorithms have been developed that exploit Toeplitz structure to gain computational efficiency when solving these systems. The…

Numerical Analysis · Mathematics 2015-06-15 Christopher Turnes , Doru Balcan , Justin Romberg

The reconstruction of images from their corresponding noisy Radon transform is a typical example of an ill-posed linear inverse problem as arising in the application of computerized tomography (CT). As the (naive) solution does not depend…