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We propose a method for reconstruction of the density matrix from measurable time-dependent (probability) distributions of physical quantities. The applicability of the method based on least-squares inversion is - compared with other…

Quantum Physics · Physics 2016-09-08 T. Opatrny , D. -G. Welsch , W. Vogel

The popular VQ-VAE models reconstruct images through learning a discrete codebook but suffer from a significant issue in the rapid quality degradation of image reconstruction as the compression rate rises. One major reason is that a higher…

Computer Vision and Pattern Recognition · Computer Science 2023-11-07 Xinmiao Lin , Yikang Li , Jenhao Hsiao , Chiuman Ho , Yu Kong

For supernovae gravitational wave signal analysis which intend to reconstruct supernova gravitational waves waveforms, we compare the performance of short-time Fourier transform (STFT), the synchroextracting transform (SET) and…

High Energy Astrophysical Phenomena · Physics 2020-10-28 Zhuotao Li , Xilong Fan , Gang Yu

In many mechanical, electrical, and general physical systems evolving over time or space, spectral analysis methods as Fast Fourier Transform (FFT), Short Term Fourier Transform (STFT), Power Spectrum Density (PSD) plays a very important…

Signal Processing · Electrical Eng. & Systems 2023-06-21 Andreas Tuor , Nico Canzani , Tobias Rüggeberg , Stefan Gorenflo , Gerd Simons , Bruno Bättig , Daniel Iseli

We present a new structure-preserving model order reduction (MOR) framework for large-scale port-Hamiltonian descriptor systems (pH-DAEs). Our method exploits the structural properties of the Rosenbrock system matrix for this system class…

Systems and Control · Electrical Eng. & Systems 2022-10-31 Tim Moser , Boris Lohmann

In this paper, a reduced-order model (ROM) based on the proper orthogonal decomposition and the discrete empirical interpolation method is proposed for efficiently simulating time-fractional partial differential equations (TFPDEs). Both…

Numerical Analysis · Mathematics 2024-02-07 Hongfei Fu , Hong Wang , Zhu Wang

A novel method for performing model updating on finite element models is presented. The approach is particularly tailored to modal analyses of buildings, by which the lowest frequencies, obtained by using sensors and system identification…

Numerical Analysis · Mathematics 2018-07-18 Maria Girardi , Cristina Padovani , Daniele Pellegrini , Margherita Porcelli , Leonardo Robol

A recently introduced representation by a set of Wang tiles -- a generalization of the traditional Periodic Unit Cell based approach -- serves as a reduced geometrical model for materials with stochastic heterogeneous microstructure,…

Materials Science · Physics 2020-10-07 M. Doškář , J. Zeman , P. Krysl , J. Novák

This paper presents joint sampling frequency offset (SFO) estimation and compensation algorithms based on the Farrow structure. Unlike conventional approaches that treat estimation and compensation separately, the proposed framework…

Signal Processing · Electrical Eng. & Systems 2026-03-03 Deijany Rodriguez Linares , Oksana Moryakova , Håkan Johansson

Accelerating magnetic resonance image (MRI) reconstruction process is a challenging ill-posed inverse problem due to the excessive under-sampling operation in k-space. In this paper, we propose a recurrent transformer model, namely…

Image and Video Processing · Electrical Eng. & Systems 2022-01-31 Pengfei Guo , Yiqun Mei , Jinyuan Zhou , Shanshan Jiang , Vishal M. Patel

Numerical simulations of contaminant dispersion, as after a gas leakage incident on a chemical plant, can provide valuable insights for both emergency response and preparedness. Simulation approaches combine incompressible Navier-Stokes…

Computational Engineering, Finance, and Science · Computer Science 2026-03-05 Lisa Kühn , Jacopo Bonari , Max von Danwitz , Alexander Popp

Multi-Output Regression (MOR) has been widely used in scientific data analysis for decision-making. Unlike traditional regression models, MOR aims to simultaneously predict multiple real-valued outputs given an input. However, the…

Machine Learning · Computer Science 2024-10-22 Renyuan Li , Zhehui Chen , Guanyi Wang

The use of Fourier methods in wave-front reconstruction can significantly reduce the computation time for large telescopes with a high number of degrees of freedom. However, Fourier algorithms for discrete data require a rectangular data…

Instrumentation and Methods for Astrophysics · Physics 2017-06-07 Charlotte Z. Bond , Carlos M. Correia , Jean-François Sauvage , Benoit Neichel , Thierry Fusco

This article is intended to supplement our 2015 paper in Medical Physics titled "Noise properties of CT images reconstructed by use of constrained total-variation, data-discrepancy minimization", in which ordered subsets methods were…

Medical Physics · Physics 2016-03-30 Sean Rose , Martin S. Andersen , Emil Y. Sidky , Xiaochuan Pan

In projection-based model order reduction, a reduced-order approximation of the original full-order system is obtained by projecting it onto a reduced subspace that contains its dominant characteristics. The problem of frequency-weighted…

Systems and Control · Electrical Eng. & Systems 2021-05-04 Umair Zulfiqar , Victor Sreeram , Mian Ilyas Ahmad , Xin Du

In many applications, projection-based reduced-order models (ROMs) have demonstrated the ability to provide rapid approximate solutions to high-fidelity full-order models (FOMs). However, there is no a priori assurance that these…

Numerical Analysis · Computer Science 2020-04-22 Philip A. Etter , Kevin T. Carlberg

The accelerated MRI reconstruction process presents a challenging ill-posed inverse problem due to the extensive under-sampling in k-space. Recently, Vision Transformers (ViTs) have become the mainstream for this task, demonstrating…

Image and Video Processing · Electrical Eng. & Systems 2024-12-17 Yucong Meng , Zhiwei Yang , Yonghong Shi , Zhijian Song

Purpose: Recent developments in hardware design enable the use of Fast Field-Cycling (FFC) techniques in MRI to exploit the different relaxation rates at very low field strength, achieving novel contrast. The method opens new avenues for in…

Signal Processing · Electrical Eng. & Systems 2021-05-19 Markus Bödenler , Oliver Maier , Rudolf Stollberger , Lionel M. Broche , P. James Ross , Mary-Joan MacLeod , Hermann Scharfetter

The non-uniform sampling is a powerful approach to enable fast acquisition but requires sophisticated reconstruction algorithms. Faithful reconstruction from partial sampled exponentials is highly expected in general signal processing and…

In nonlinear imaging problems whose forward model is described by a partial differential equation (PDE), the main computational bottleneck in solving the inverse problem is the need to solve many large-scale discretized PDEs at each step of…

Numerical Analysis · Mathematics 2016-03-08 Meghan O'Connell , Misha E. Kilmer , Eric de Sturler , Serkan Gugercin