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Time series anomaly detection has been recognized as of critical importance for the reliable and efficient operation of real-world systems. Many anomaly detection methods have been developed based on various assumptions on anomaly…

Machine Learning · Computer Science 2022-07-28 Jiuqi Elise Zhang , Di Wu , Benoit Boulet

Anomaly detection in complex dynamical systems is essential for ensuring reliability, safety, and efficiency in industrial and cyber-physical infrastructures. Predictive maintenance helps prevent costly failures, while cybersecurity…

Machine Learning · Computer Science 2025-09-25 Michael Somma , Thomas Gallien , Branka Stojanovic

This paper proposes a graph linear canonical transform (GLCT) by decomposing the linear canonical parameter matrix into fractional Fourier transform, scale transform, and chirp modulation for graph signal processing. The GLCT enables…

General Mathematics · Mathematics 2024-07-18 Jian Yi Chen , Bing Zhao Li

Convolutional Neural Networks (CNNs) are widely used in fault diagnosis of mechanical systems due to their powerful feature extraction and classification capabilities. However, the CNN is a typical black-box model, and the mechanism of…

Artificial Intelligence · Computer Science 2024-03-12 Qian Chen , Xingjian Dong , Guowei Tu , Dong Wang , Baoxuan Zhao , Zhike Peng

Recent studies have suggested frequency-domain Data augmentation (DA) is effec tive for time series prediction. Existing frequency-domain augmentations disturb the original data with various full-spectrum noises, leading to excess domain…

Machine Learning · Computer Science 2024-05-28 Kai Zhao , Zuojie He , Alex Hung , Dan Zeng

With the rapid development of facial forgery techniques, forgery detection has attracted more and more attention due to security concerns. Existing approaches attempt to use frequency information to mine subtle artifacts under high-quality…

Computer Vision and Pattern Recognition · Computer Science 2021-12-30 Qiqi Gu , Shen Chen , Taiping Yao , Yang Chen , Shouhong Ding , Ran Yi

This brief aims at the issue of globally composite-learning-based neural fast finite-time (F-FnT) tracking control for a class of uncertain systems in strict-feedback form subject to nonlinearly periodic disturbances. First, uncertain…

Systems and Control · Electrical Eng. & Systems 2023-09-22 Xidong Wang , Zhan Li , Zhen He

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

In this paper, we revisited the role of data augmentation in contrastive learning for sequential recommendation, revealing its inherent bias against low-frequency items and sparse user behaviors. To address this limitation, we proposed…

Information Retrieval · Computer Science 2026-01-27 Zhikai Wang , Weihua Zhang

Anomaly detection is referred to as a process in which the aim is to detect data points that follow a different pattern from the majority of data points. Anomaly detection methods suffer from several well-known challenges that hinder their…

Machine Learning · Computer Science 2021-08-31 Kasra Babaei , Zhi Yuan Chen , Tomas Maul

Spectral analysis provides one of the most effective paradigms for information-preserving dimensionality reduction, as simple descriptions of naturally occurring signals are often obtained via few terms of periodic basis functions. In this…

Machine Learning · Computer Science 2022-11-29 Michael Poli , Stefano Massaroli , Federico Berto , Jinykoo Park , Tri Dao , Christopher Ré , Stefano Ermon

Data augmentation methods are commonly integrated into the training of anomaly detection models. Previous approaches have primarily focused on replicating real-world anomalies or enhancing diversity, without considering that the standard of…

Artificial Intelligence · Computer Science 2024-12-30 Jiang Lin , Yaping Yan

Time series data, characterized by its intrinsic long and short-range dependencies, poses a unique challenge across analytical applications. While Transformer-based models excel at capturing long-range dependencies, they face limitations in…

Machine Learning · Computer Science 2024-05-07 Emadeldeen Eldele , Mohamed Ragab , Zhenghua Chen , Min Wu , Xiaoli Li

Anomaly detection is an important problem with applications in various domains such as fraud detection, pattern recognition or medical diagnosis. Several algorithms have been introduced using classical computing approaches. However, using…

Machine Learning · Computer Science 2024-10-10 Robin Frehner , Kurt Stockinger

This paper introduces a couple of new time-frequency transforms, designed to adapt their scale to specific features of the analyzed function. Such an adaptation is implemented via so-called focus functions, which control the window scale as…

Classical Analysis and ODEs · Mathematics 2024-06-19 Pierre Warion , Bruno Torrésani

Anomaly detection in time series is essential for industrial monitoring and environmental sensing, yet distinguishing anomalies from complex patterns remains challenging. Existing methods like the Anomaly Transformer and DCdetector have…

Machine Learning · Computer Science 2025-05-20 Abdellah Zakaria Sellam , Ilyes Benaissa , Abdelmalik Taleb-Ahmed , Luigi Patrono , Cosimo Distante

Optical coherence tomography (OCT) has stimulated a wide range of medical image-based diagnosis and treatment in fields such as cardiology and ophthalmology. Such applications can be further facilitated by deep learning-based…

Medical Physics · Physics 2023-07-24 Xueshen Li , Zhenxing Dong , Hongshan Liu , Jennifer J. Kang-Mieler , Yuye Ling , Yu Gan

Deepfake detectors often struggle to generalize to novel forgery types due to biases learned from limited training data. In this paper, we identify a new type of model bias in the frequency domain, termed spectral bias, where detectors…

Computer Vision and Pattern Recognition · Computer Science 2025-09-29 Hossein Kashiani , Niloufar Alipour Talemi , Fatemeh Afghah

The complexity of modern electro-mechanical systems require the development of sophisticated diagnostic methods like anomaly detection capable of detecting deviations. Conventional anomaly detection approaches like signal processing and…

Machine Learning · Computer Science 2025-01-07 Abhishek Srinivasan , Varun Singapuri Ravi , Juan Carlos Andresen , Anders Holst

2D convolution is widely used in sound event detection (SED) to recognize two dimensional time-frequency patterns of sound events. However, 2D convolution enforces translation equivariance on sound events along both time and frequency axis…

Audio and Speech Processing · Electrical Eng. & Systems 2022-07-05 Hyeonuk Nam , Seong-Hu Kim , Byeong-Yun Ko , Yong-Hwa Park