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A streaming algorithm to compute the spectral proper orthogonal decomposition (SPOD) of stationary random processes is presented. As new data becomes available, an incremental update of the truncated eigenbasis of the estimated…

Fluid Dynamics · Physics 2019-01-14 Oliver T. Schmidt , Aaron Towne

This contribution is a follow-up of a recent paper by the authors on adaptive, non-linear time-frequency transforms, focusing on the STFT based transforms. The adaptivity is provided by a focus function, that depends on the analyzed…

Classical Analysis and ODEs · Mathematics 2025-06-11 Pierre Warion , Bruno Torrésani

The synchrosqueezing transform (SST) has been developed as a powerful EMD-like tool for instantaneous frequency (IF) estimation and component separation of non-stationary multicomponent signals. Recently, a direct method of the…

Numerical Analysis · Mathematics 2020-10-22 Charles K. Chui , Qingtang Jiang , Lin Li , Jian Lu

We propose a novel approach for time-scale modification of audio signals. Unlike traditional methods that rely on the framing technique or the short-time Fourier transform to preserve the frequency during temporal stretching, our neural…

Sound · Computer Science 2023-10-09 Ernie Chu , Ju-Ting Chen , Chia-Ping Chen

In coherent imaging systems, speckle is a signal-dependent noise that visually strongly degrades images' appearance. A huge amount of SAR data has been acquired from different sensors with different wavelengths, resolutions, incidences and…

Computer Vision and Pattern Recognition · Computer Science 2024-02-16 Weiying Zhao , Paul Riot , Charles-Alban Deledalle , Henri Maître , Jean-Marie Nicolas , Florence Tupin

A Python package for the calculation of spectrograms with optimized time and frequency resolution for application in the analysis of numerical simulations on ultrashort pulse propagation is presented. Gabor's uncertainty principle prevents…

Computational Physics · Physics 2018-09-05 O. Melchert , B. Roth , U. Morgner , A. Demircan

We introduce a new numerical method for solving time-harmonic acoustic scattering problems. The main focus is on plane waves scattered by smoothly varying material inhomogeneities. The proposed method works for any frequency $\omega$, but…

Numerical Analysis · Mathematics 2022-01-14 Anton Arnold , Sjoerd Geevers , Ilaria Perugia , Dmitry Ponomarev

We present a new explicit local space-time adaptive framework to decrease the time required for monodomain simulations for cardiac electrophysiology. Based on the localized structure of the steep activation wavefront in solutions to…

Numerical Analysis · Mathematics 2025-02-03 Dennis Ogiermann , Daniel Balzani , Luigi E. Perotti

We consider sparseness properties of adaptive time-frequency representations obtained using nonstationary Gabor frames (NSGFs). NSGFs generalize classical Gabor frames by allowing for adaptivity in either time or frequency. It is known that…

Functional Analysis · Mathematics 2018-01-03 Emil Solsbæk Ottosen , Morten Nielsen

The audio spectrogram is a time-frequency representation that has been widely used for audio classification. One of the key attributes of the audio spectrogram is the temporal resolution, which depends on the hop size used in the Short-Time…

Sound · Computer Science 2024-01-15 Haohe Liu , Xubo Liu , Qiuqiang Kong , Wenwu Wang , Mark D. Plumbley

Fourier-encoded implicit neural representations (INRs) have shown strong capability in modeling continuous signals from discrete samples. However, conventional Fourier feature mappings use a fixed set of frequencies over the entire spatial…

Computer Vision and Pattern Recognition · Computer Science 2026-04-21 Ligen Shi , Jun Qiu , Yuhang Zheng , Zengyu Pang , Chang Liu

Change detection within an audio stream is an important task in several domains, such as classification and segmentation of a sound or of a music piece, as well as indexing of broadcast news or surveillance applications. In this paper we…

Sound · Computer Science 2011-09-28 Marco Liuni , Axel Röbel , Marco Romito , Xavier Rodet

Time-domain speech enhancement (SE) has recently been intensively investigated. Among recent works, DEMUCS introduces multi-resolution STFT loss to enhance performance. However, some resolutions used for STFT contain non-stationary signals,…

Sound · Computer Science 2023-03-28 Hao Shi , Masato Mimura , Longbiao Wang , Jianwu Dang , Tatsuya Kawahara

In this paper, we present strip-map mode spaceborne Synthetic Aperture Radar (SAR) imaging with the focus on Doppler centroid frequency estimation. The non-zero Doppler centroid frequency is the result of non-zero squint angle which if it…

Signal Processing · Electrical Eng. & Systems 2025-08-01 Shahrokh Hamidi

Sampling is classically performed by recording the amplitude of an input signal at given time instants; however, sampling and reconstructing a signal using multiple devices in parallel becomes a more difficult problem to solve when the…

Signal Processing · Electrical Eng. & Systems 2020-04-22 Karen Adam , Adam Scholefield , Martin Vetterli

Time-frequency representation (TFR) allowing for mode reconstruction plays a significant role in interpreting and analyzing the nonstationary signal constituted of various modes. However, it is difficult for most previous methods to handle…

Signal Processing · Electrical Eng. & Systems 2021-09-01 Haijian Zhang , Guang Hua

Shannon Entropy is the preeminent tool for measuring the level of uncertainty (and conversely, information content) in a random variable. In the field of communications, entropy can be used to express the information content of given…

Information Theory · Computer Science 2024-11-06 Bill Kay , Audun Myers , Thad Boydston , Emily Ellwein , Cameron Mackenzie , Iliana Alvarez , Erik Lentz

An algorithmic limit of compressed sensing or related variable-selection problems is analytically evaluated when a design matrix is given by an overcomplete random matrix. The replica method from statistical mechanics is employed to derive…

Disordered Systems and Neural Networks · Physics 2018-11-14 Tomoyuki Obuchi , Yoshinori Nakanishi-Ohno , Masato Okada , Yoshiyuki Kabashima

In most work to date, graph signal sampling and reconstruction algorithms are intrinsically tied to graph properties, assuming bandlimitedness and optimal sampling set choices. However, practical scenarios often defy these assumptions,…

Signal Processing · Electrical Eng. & Systems 2024-01-23 Darukeesan Pakiyarajah , Eduardo Pavez , Antonio Ortega

This paper addresses the problem of selecting an optimal sampling set for signals on graphs. The proposed sampling set selection (SSS) is based on a localization operator that can consider both vertex domain and spectral domain…

Signal Processing · Electrical Eng. & Systems 2020-03-11 Akie Sakiyama , Yuichi Tanaka , Toshihisa Tanaka , Antonio Ortega