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Improving the generalization ability of Deep Neural Networks (DNNs) is critical for their practical uses, which has been a longstanding challenge. Some theoretical studies have uncovered that DNNs have preferences for some frequency…

Computer Vision and Pattern Recognition · Computer Science 2023-03-28 Shiqi Lin , Zhizheng Zhang , Zhipeng Huang , Yan Lu , Cuiling Lan , Peng Chu , Quanzeng You , Jiang Wang , Zicheng Liu , Amey Parulkar , Viraj Navkal , Zhibo Chen

Many real-world time series exhibit strong periodic structures arising from physical laws, human routines, or seasonal cycles. However, modern deep forecasting models often fail to capture these recurring patterns due to spectral bias and a…

Machine Learning · Computer Science 2025-08-05 Menglin Kong , Vincent Zhihao Zheng , Lijun Sun

The characterization of non-stationary signals requires joint time and frequency information. However, time (t) and frequency (omega) being non-commuting variables there cannot be a joint probability density in the (t,omega) plane and the…

Data Analysis, Statistics and Probability · Physics 2007-05-23 V. I. Man'ko , R. Vilela Mendes

In the last twenty years modulation spaces, introduced by H. G. Feichtinger in 1983, have been successfully addressed to the study of signal analysis, PDE's, pseudodifferential operators, quantum mechanics, by hundreds of contributions. In…

Functional Analysis · Mathematics 2023-02-13 Elena Cordero , Luigi Rodino

The data analysis of space-based gravitational wave detectors like Taiji faces significant challenges from non-stationary noise, which compromises the efficacy of traditional frequency-domain analysis. This work proposes a unified framework…

General Relativity and Quantum Cosmology · Physics 2025-06-23 Minghui Du , Ziren Luo , Peng Xu

In orthogonal time frequency space (OTFS) modulation, information-carrying symbols reside in the delay-Doppler (DD) domain. By operating in the DD domain, an appealing property for communication arises: time-frequency (TF) dispersive…

Signal Processing · Electrical Eng. & Systems 2022-12-07 Franz Lampel , Alex Alvarado , Frans M. J. Willems

Stationary Random Functions have been successfully applied in geostatistical applications for decades. In some instances, the assumption of a homogeneous spatial dependence structure across the entire domain of interest is unrealistic. A…

Methodology · Statistics 2014-12-04 Francky Fouedjio , Nicolas Desassis , Thomas Romary

The time-frequency integrals and the two-dimensional stationary phase method are applied to study the electromagnetic waves radiated by moving modulated sources in dispersive media. We show that such unified approach leads to explicit…

Quantum Physics · Physics 2012-12-11 Gennadiy Burlak , Vladimir Rabinovich

Time domain identification is studied in this paper for parameters of a continuous-time multi-input multi-output descriptor system, with these parameters affecting system matrices through a linear fractional transformation. Sampling is…

Multiagent Systems · Computer Science 2025-06-17 Tong Zhou

A novel addition to the family of integral transforms, the quadratic phase Fourier transform (QPFT) embodies a variety of signal processing tools, including the Fourier transform (FT), fractional Fourier transform (FRFT), linear canonical…

Functional Analysis · Mathematics 2024-02-20 Aamir Hamid Dar

Spectral analysis in conjunction with discrete data in one and more dimensions can become a challenging task, because the methods are sometimes difficult to understand. This paper intends to provide an overview about the usage of the…

Methodology · Statistics 2017-08-01 Martin Seilmayer , Matthias Ratajczak

In this paper, a novel and robust algorithm is proposed for adaptive beamforming based on the idea of reconstructing the autocorrelation sequence (ACS) of a random process from a set of measured data. This is obtained from the first column…

Information Theory · Computer Science 2021-06-25 Saeed Mohammadzadeh , Vitor H. Nascimento , Rodrigo C. de Lamare , Osman Kukrer

Efficiently modeling spatio-temporal (ST) physical processes and observations presents a challenging problem for the deep learning community. Many recent studies have concentrated on meticulously reconciling various advantages, leading to…

Artificial Intelligence · Computer Science 2024-06-04 Hao Wu , Yuxuan Liang , Wei Xiong , Zhengyang Zhou , Wei Huang , Shilong Wang , Kun Wang

Pseudospectral numerical schemes for solving the Dirac equation in general static curved space are derived using a pseudodifferential representation of the Dirac equation along with a simple Fourier-basis technique. Owing to the presence of…

Numerical Analysis · Mathematics 2020-04-22 Xavier Antoine , François Fillion-Gourdeau , Emmanuel Lorin , Steve McLean

This paper introduces a version of empirical likelihood based on the periodogram and spectral estimating equations. This formulation handles dependent data through a data transformation (i.e., a Fourier transform) and is developed in terms…

Statistics Theory · Mathematics 2011-11-10 Daniel J. Nordman , Soumendra N. Lahiri

This paper presents a gradient-based method for on-the-fly optimization for both per-frame and per-frequency window length of the short-time Fourier transform (STFT), related to previous work in which we developed a differentiable version…

Signal Processing · Electrical Eng. & Systems 2023-08-07 Maxime Leiber , Yosra Marnissi , Axel Barrau , Mohammed El Badaoui

Long-term time series forecasting is a long-standing challenge in various applications. A central issue in time series forecasting is that methods should expressively capture long-term dependency. Furthermore, time series forecasting…

Machine Learning · Computer Science 2024-11-06 Xingyu Zhang , Siyu Zhao , Zeen Song , Huijie Guo , Jianqi Zhang , Changwen Zheng , Wenwen Qiang

Fourier representation (FR) is an indispensable mathematical formulation for modeling and analysis of physical phenomenon, engineering systems and signals in numerous applications. In this study, we present the generalized Fourier…

Signal Processing · Electrical Eng. & Systems 2020-08-28 Pushpendra Singh

The problem of broad practical interest in spatiotemporal data analysis, i.e., discovering interpretable dynamic patterns from spatiotemporal data, is studied in this paper. Towards this end, we develop a time-varying reduced-rank vector…

Machine Learning · Computer Science 2022-11-29 Xinyu Chen , Chengyuan Zhang , Xiaoxu Chen , Nicolas Saunier , Lijun Sun

The time-frequency content of a signal can be measured by the Gabor transform or windowed Fourier transform. This is a function defined on phase space that is computed by taking the Fourier transform of the product of the signal against a…

funct-an · Mathematics 2008-02-03 Jayakumar Ramanathan , Pankaj Topiwala