arXiv AI

CLOSURE: Cross-Channel Closure for Multivariate Time Series Anomaly Detection

CLOSURE introduces a two‑task framework for multivariate time‑series anomaly detection that separately evaluates recoverability and cross‑channel consistency. The recoverability task uses a diffusion reconstructor conditioned on a discrete memory of normal temporal bases, while the consistency task employs a relation‑closure operator that predicts each channel from its peers using sparse signed gates. Experiments demonstrate that combining these two scores outperforms recent reconstruction, frequency, and topology‑based detectors on public benchmarks, highlighting the importance of assessing consistency alongside recoverability.

arXiv Machine Learning
Sep 16

Robust Fault Detection in Mechanical Multimodal Time Series via Self-Supervised Cross-Modal Reconstruction

The paper introduces a multimodal anomaly detection framework that uses cross‑modal reconstruction of heterogeneous time‑series sensor data to detect faults in industrial systems. By learning to reconstruct each modality from the others, the method leverages complementary information across sensing channels without requiring explicit temporal alignment or identical sampling rates. An adaptive test‑time thresholding mechanism further improves robustness to distribution shifts caused by changing operating conditions, as demonstrated by strong fault detection performance in three industrial case studies, especially under out‑of‑distribution regimes.

By Magnus Munk Jensen, Dorte Hammersh{\o}i, Rafa{\l} Wi\'sniewski, Olga Fink
arXiv Machine Learning
Oct 2

LEARN-TS: LLM-Enhanced Alignment and Reconstruction with Normality Guidance for Multivariate Time-Series Anomaly Detection

LEARN-TS is a method for multivariate time‑series anomaly detection that uses a frozen language model to generate two semantic representations: one that captures window‑specific observation context without exact numerical values, and another that provides a fixed, dataset‑agnostic normality prompt. These representations guide a patch‑masked reconstruction process, allowing the model to estimate normality discrepancy and produce timestamp‑level anomaly evidence. Experiments on four benchmarks show that LEARN‑TS achieves the best mean performance in 13 of 16 dataset‑metric comparisons, and ablation studies confirm the benefits of observation conditioning, joint normality alignment, and semantic references.

By Jahyeob Koo, Kio Yun, Byoungmo Koo, Jun-Geol Baek
arXiv AI
2d ago

From Reconstruction to Imputation: Test-Time Optimization for Missing Time-Series Channels

The paper proposes a test‑time optimization technique that converts a frozen sequence reconstructor into an imputer for missing time‑series channels. By treating missing entries as optimization variables, clamping observed data, and backpropagating to minimize reconstruction error only on observed coordinates, the method avoids the need for artificial mask augmentation or full‑channel dropout during training. Experiments on five real‑world datasets show that this refinement improves mean absolute error in most dataset‑backbone combinations and can outperform mask‑aware imputers on some datasets, though it requires more inference time and depends on cross‑channel coupling.

By Bj\"orn Ludwig, Alexander Windmann, Ren\'e Heesch, Oliver Niggemann
arXiv AI
Oct 26

TENET: Time-point Encoding Network for Multivariate Time Series Anomaly Detection

TENET is a Time-point Encoding Network designed for unsupervised multivariate time series anomaly detection. It reframes the task as estimating current-point system-state compatibility by constructing a latent representation of the target time point from variable-level temporal context within an input window. The model uses a temporal layer to retrieve context relative to the current point, encodes time with point-centered embeddings, and adaptively mixes this context with the current representation, then evaluates the latent state with a fixed standard-normal negative log-likelihood score, achieving state-of-the-art performance across benchmark datasets.

By Dongchan Cho, Juwon Hwang, Keumyeong Kang, Jiho Han, Namsoon Jung