When Model Meets New Normals: Test-time Adaptation for Unsupervised Time-series Anomaly Detection
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Abstract (arXiv)
Time-series anomaly detection deals with the problem of detecting anomalous timesteps by learning normality from the sequence of observations. However, the concept of normality evolves over time, leading to a "new normal problem", where the distribution of normality can be changed due to the distribution shifts between training and test data. This paper highlights the prevalence of the new normal problem in unsupervised time-series anomaly detection studies. To tackle this issue, we propose a simple yet effective test-time adaptation strategy based on trend estimation and a self-supervised approach to learning new normalities during inference. Extensive experiments on real-world benchmarks demonstrate that incorporating the proposed strategy into the anomaly detector consistently improves the model's performance compared to the baselines, leading to robustness to the distribution shifts.
Key facts. Cited by 17 papers in the map (data through 7 Oct 2026). Builds on 14 of its 48 references that are in the map. First posted on arXiv 19 Dec 2023.
Builds on
14 of 48 references.
References · 14
- 2015Domain-Adversarial Training of Neural Networkscited by 3,023
- 2020In Search of Lost Domain Generalizationcited by 1,042
- 2020Do We Really Need to Access the Source Data? Source Hypothesis Transfer for Unsupervised Domain Adaptationcited by 844
- 2017Unsupervised Anomaly Detection with Generative Adversarial Networks to Guide Marker Discoverycited by 566
- 2020A Survey of Deep Active Learningcited by 547
- 2022Efficient Test-Time Model Adaptation without Forgettingcited by 467
- 2020A Unifying Review of Deep and Shallow Anomaly Detectioncited by 423
- 2021Anomaly Transformer: Time Series Anomaly Detection with Association Discrepancycited by 387
- 2018Unsupervised Anomaly Detection via Variational Auto-Encoder for Seasonal KPIs in Web Applicationscited by 223
- 2016LSTM-based Encoder-Decoder for Multi-sensor Anomaly Detectioncited by 213
- 2017A Multimodal Anomaly Detector for Robot-Assisted Feeding Using an LSTM-based Variational Autoencodercited by 209
- 2018Generative Adversarial Active Learning for Unsupervised Outlier Detectioncited by 65
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Citing papers per year: 2024: 3; 2025: 3; 2026: 11.
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- 2025Accurate Parameter-Efficient Test-Time Adaptation for Time Series Forecastingcited by 13
- 2024PatchAD: A Lightweight Patch-based MLP-Mixer for Time Series Anomaly Detectioncited by 12
- 2024SimAD: A Simple Dissimilarity-based Approach for Time Series Anomaly Detectioncited by 6
- 2025Test-Time Distillation for Continual Model Adaptationcited by 5
- 2026AnomaMind: Agentic Time Series Anomaly Detection with Tool-Augmented Reasoningcited by 3
- 2024GDFlow: Anomaly Detection with NCDE-based Normalizing Flow for Advanced Driver Assistance Systemcited by 2
- 2026naPINN: Noise-Adaptive Physics-Informed Neural Networks for Recovering Physics from Corrupted Measurementcited by 1
- 2026Position: Universal Time Series Foundation Models Rest on a Category Errorcited by 1
- 2026Adapt Data to Model: Adaptive Transformation Optimization for Domain-shared Time Series Foundation Modelscited by 1
- 2025CCE: Confidence-Consistency Evaluation for Time Series Anomaly Detectioncited by 0
- 2026COMET: Codebook-based Online-adaptive Multi-scale Embedding for Time-series Anomaly Detectioncited by 0
- 2026Catching Every Ripple: Enhanced Anomaly Awareness via Dynamic Concept Adaptationcited by 0
5 more
- 2026Just Repair: A Minimal Denoising Network for Time Series Anomaly Detectioncited by 0
- 2026When Normality Shifts: Risk-Aware Test-Time Adaptation for Unsupervised Tabular Anomaly Detectioncited by 0
- 2026Bridging Classification and Reconstruction: Cooperative Time Series Anomaly Detectioncited by 0
- 2026Efficient Regression Models for Scan Statisticscited by 0
- 2026Supervision Recovery for Time Series Anomaly Detection via Context-Anchored Pairingcited by 0
- 2026Supervision Recovery for Time Series Anomaly Detection via Context-Anchored Pairing27 Sep 2026
- 2026Efficient Regression Models for Scan Statistics23 Aug 2026
- 2026Bridging Classification and Reconstruction: Cooperative Time Series Anomaly Detection25 May 2026
- 2026When Normality Shifts: Risk-Aware Test-Time Adaptation for Unsupervised Tabular Anomaly Detection11 May 2026
- 2026Just Repair: A Minimal Denoising Network for Time Series Anomaly Detection19 Apr 2026
- 2026Catching Every Ripple: Enhanced Anomaly Awareness via Dynamic Concept Adaptation16 Apr 2026
- 2026Adapt Data to Model: Adaptive Transformation Optimization for Domain-shared Time Series Foundation Models28 Feb 2026
- 2026AnomaMind: Agentic Time Series Anomaly Detection with Tool-Augmented Reasoning14 Feb 2026
- 2026Position: Universal Time Series Foundation Models Rest on a Category Error5 Feb 2026
- 2026COMET: Codebook-based Online-adaptive Multi-scale Embedding for Time-series Anomaly Detection2 Feb 2026
- 2026naPINN: Noise-Adaptive Physics-Informed Neural Networks for Recovering Physics from Corrupted Measurement30 Jan 2026
- 2025CCE: Confidence-Consistency Evaluation for Time Series Anomaly Detection1 Sep 2025
5 more
- 2025Accurate Parameter-Efficient Test-Time Adaptation for Time Series Forecasting29 Jun 2025
- 2025Test-Time Distillation for Continual Model Adaptation3 Jun 2025
- 2024GDFlow: Anomaly Detection with NCDE-based Normalizing Flow for Advanced Driver Assistance System9 Sep 2024
- 2024SimAD: A Simple Dissimilarity-based Approach for Time Series Anomaly Detection18 May 2024
- 2024PatchAD: A Lightweight Patch-based MLP-Mixer for Time Series Anomaly Detection18 Jan 2024
- 2025Accurate Parameter-Efficient Test-Time Adaptation for Time Series Forecastingcited by 13
- 2024PatchAD: A Lightweight Patch-based MLP-Mixer for Time Series Anomaly Detectioncited by 12
- 2024SimAD: A Simple Dissimilarity-based Approach for Time Series Anomaly Detectioncited by 6
- 2025Test-Time Distillation for Continual Model Adaptationcited by 5
- 2024GDFlow: Anomaly Detection with NCDE-based Normalizing Flow for Advanced Driver Assistance Systemcited by 2
- 2026naPINN: Noise-Adaptive Physics-Informed Neural Networks for Recovering Physics from Corrupted Measurementcited by 1
- 2026Position: Universal Time Series Foundation Models Rest on a Category Errorcited by 1
- 2026Adapt Data to Model: Adaptive Transformation Optimization for Domain-shared Time Series Foundation Modelscited by 1
- 2025CCE: Confidence-Consistency Evaluation for Time Series Anomaly Detectioncited by 0
- 2026COMET: Codebook-based Online-adaptive Multi-scale Embedding for Time-series Anomaly Detectioncited by 0
- 2026Catching Every Ripple: Enhanced Anomaly Awareness via Dynamic Concept Adaptationcited by 0
- 2026Just Repair: A Minimal Denoising Network for Time Series Anomaly Detectioncited by 0
12 most cited of 16 All 16 (JSON)
- 2026Supervision Recovery for Time Series Anomaly Detection via Context-Anchored Pairing27 Sep 2026
- 2026Efficient Regression Models for Scan Statistics23 Aug 2026
- 2026Bridging Classification and Reconstruction: Cooperative Time Series Anomaly Detection25 May 2026
- 2026When Normality Shifts: Risk-Aware Test-Time Adaptation for Unsupervised Tabular Anomaly Detection11 May 2026
- 2026Just Repair: A Minimal Denoising Network for Time Series Anomaly Detection19 Apr 2026
- 2026Catching Every Ripple: Enhanced Anomaly Awareness via Dynamic Concept Adaptation16 Apr 2026
- 2026Adapt Data to Model: Adaptive Transformation Optimization for Domain-shared Time Series Foundation Models28 Feb 2026
- 2026Position: Universal Time Series Foundation Models Rest on a Category Error5 Feb 2026
- 2026COMET: Codebook-based Online-adaptive Multi-scale Embedding for Time-series Anomaly Detection2 Feb 2026
- 2026naPINN: Noise-Adaptive Physics-Informed Neural Networks for Recovering Physics from Corrupted Measurement30 Jan 2026
- 2025CCE: Confidence-Consistency Evaluation for Time Series Anomaly Detection1 Sep 2025
- 2025Accurate Parameter-Efficient Test-Time Adaptation for Time Series Forecasting29 Jun 2025
12 newest of 16 All 16 (JSON)