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We develop a novel wave imaging scheme for reconstructing the shape of an inhomogeneous scatterer and we consider the inverse acoustic obstacle scattering problem as a prototype model for our study. There exists a wealth of reconstruction…

Analysis of PDEs · Mathematics 2020-01-08 Hongyu Liu , Xiaodong Liu , Xianchao Wang , Yuliang Wang

Electro-seismic imaging is a novel hybrid imaging modality in geophysical exploration. This paper concerns an inverse source problem for Biot's equations that arise in electro-seismic imaging. Using the time reversal method, we derive an…

Analysis of PDEs · Mathematics 2019-09-04 Yixian Gao , Peijun Li , Yang Yang

Consider the elastic scattering of a time-harmonic wave by multiple well separated rigid particles in two dimensions. To avoid using the complex Green's tensor of the elastic wave equation, we utilize the Helmholtz decomposition to convert…

Numerical Analysis · Mathematics 2020-08-17 Jun Lai , Peijun Li

Time-resolved spectroscopy provides the main tool for analyzing the dynamics of excitonic energy transfer in light-harvesting complexes. To infer time-scales and effective coupling parameters from experimental data requires to develop…

Chemical Physics · Physics 2018-11-28 Tobias Kramer , Mirta Rodriguez , Yaroslav Zelinskyy

In time reversal acoustics experiments, a signal is emitted from a localized source, recorded at an array of receivers-transducers, time reversed, and finally re-emitted into the medium. A celebrated feature of time reversal experiments is…

Chaotic Dynamics · Physics 2007-05-23 Guillaume Bal , Leonid Ryzhik

This letter extends the concept of graph-frequency to graph signals that evolve with time. Our goal is to generalize and, in fact, unify the familiar concepts from time- and graph-frequency analysis. To this end, we study a joint temporal…

Machine Learning · Computer Science 2016-02-17 Andreas Loukas , Damien Foucard

We present a robust method to correct for motion and deformations for in-utero volumetric MRI time series. Spatio-temporal analysis of dynamic MRI requires robust alignment across time in the presence of substantial and unpredictable…

Computer Vision and Pattern Recognition · Computer Science 2016-08-16 Ruizhi Liao , Esra Turk , Miaomiao Zhang , Jie Luo , Ellen Grant , Elfar Adalsteinsson , Polina Golland

Full-waveform inversion (FWI) is a powerful technique for reconstructing high-resolution material parameters from seismic or ultrasound data. The conventional least-squares (\(L^{2}\)) misfit suffers from pronounced non-convexity that leads…

Optimization and Control · Mathematics 2025-08-26 Matej Neumann , Yunan Yang

In this paper, we study the truncated matrix moment problem in one variable through recursive matrix extensions. \ We give necessary and sufficient conditions for a recursive matrix extension of finite data to be a matrix moment sequence in…

Functional Analysis · Mathematics 2024-01-02 R. Curto , A. Ech-charyfy , K. Idrissi , E. H. Zerouali

We propose a natural way to generalize relative transfer functions (RTFs) to more than one source. We first prove that such a generalization is not possible using a single multichannel spectro-temporal observation, regardless of the number…

Sound · Computer Science 2015-07-02 Antoine Deleforge , Sharon Gannot , Walter Kellermann

We consider a linearised inverse conductivity problem for electromagnetic waves in a three dimensional bounded domain at a high time-harmonic frequency. Increasing stability bounds for the conductivity coefficient in the full Maxwell system…

Analysis of PDEs · Mathematics 2022-02-09 Victor Isakov , Shuai Lu , Boxi Xu

We derive expressions for the electromagnetic Green's function for a layered system using a transfer matrix technique. The expressions we arrive at makes it possible to study symmetry properties of the Green's function, such as reciprocity…

Mesoscale and Nanoscale Physics · Physics 2011-05-09 Peter Johansson

Real-time classification of Electromyography signals is the most challenging part of controlling a prosthetic hand. Achieving a high classification accuracy of EMG signals in a short delay time is still challenging. Recurrent neural…

Signal Processing · Electrical Eng. & Systems 2021-09-14 Reza Bagherian Azhiri , Mohammad Esmaeili , Mehrdad Nourani

We study the mathematical model of multiwave tomography including thermo and photoacoustic tomography with a variable speed for a fixed time interval $[0,T]$. We assume that the waves reflect from the boundary of the domain. We propose an…

Analysis of PDEs · Mathematics 2015-06-11 Plamen Stefanov , Yang Yang

Imaging of scenes using light or other wave phenomena is subject to the diffraction limit. The spatial profile of a wave propagating between a scene and the imaging system is distorted by diffraction resulting in a loss of resolution that…

Image and Video Processing · Electrical Eng. & Systems 2020-07-20 Ji Hyun Nam , Andreas Velten

The fine timing measurement (FTM) protocol is designed to determine precise ranging between Wi-Fi devices using round-trip time (RTT) measurements. However, the multipath propagation of radio waves generates inaccurate timing information,…

Networking and Internet Architecture · Computer Science 2021-12-30 Jeongsik Choi

This paper gives a remark on the Enclosure Method by considering inverse obstacle scattering problems with a single incident wave whose governing equation is given by the Helmholtz equation in two dimensions. It is concerned with the…

Analysis of PDEs · Mathematics 2011-09-21 Masaru Ikehata

We describe a new algorithm to solve the time dependent, frequency integrated radiation transport (RT) equation implicitly, which is coupled to an explicit solver for equations of magnetohydrodynamics (MHD) using {\sf Athena++}. The…

Instrumentation and Methods for Astrophysics · Physics 2021-04-07 Yan-Fei Jiang

Time-resolved MR angiography (tMRA) has been widely used for dynamic contrast enhanced MRI (DCE-MRI) due to its highly accelerated acquisition. In tMRA, the periphery of the k-space data are sparsely sampled so that neighbouring frames can…

Image and Video Processing · Electrical Eng. & Systems 2020-03-31 Eunju Cha , Hyungjin Chung , Eung Yeop Kim , Jong Chul Ye

We study the capabilities of time-modulated diffraction gratings as imaging devices. It is shown that a time-dependent but transversally homogeneous slab can be used to make a perfect image of an object in the far-field, since all the…

Optics · Physics 2022-04-05 Pawel Packo , Dani Torrent
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