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Dennis Wagner

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3 papers

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NeurIPS Conference 2025 Conference Paper

Mitigating Spurious Features in Contrastive Learning with Spectral Regularization

Naghmeh Ghanooni
Waleed Mustafa
Dennis Wagner
Sophie Fellenz
Anthony Lin
Marius Kloft

Neural networks generally prefer simple and easy-to-learn features. When these features are spuriously correlated with the labels, the network's performance can suffer, particularly for underrepresented classes or concepts. Self-supervised representation learning methods, such as contrastive learning, are especially prone to this issue, often resulting in worse performance on downstream tasks. We identify a key spectral signature of this failure: early reliance on dominant singular modes of the learned feature matrix. To mitigate this, we propose a novel framework that promotes a uniform eigenspectrum of the feature covariance matrix, encouraging diverse and semantically rich representations. Our method operates in a fully self-supervised setting, without relying on ground-truth labels or any additional information. Empirical results on SimCLR and SimSiam demonstrate consistent gains in robustness and transfer performance, suggesting broad applicability across self-supervised learning paradigms. Code: https: //github. com/NaghmehGh/SpuriousCorrelation_SSRL

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NeurIPS Conference 2025 Conference Paper

NoBOOM: Chemical Process Datasets for Industrial Anomaly Detection

Dennis Wagner
Fabian Hartung
Justus Arweiler
Aparna Muraleedharan
Indra Jungjohann
Arjun Nair
Steffen Reithermann
Ralf Schulz

Monitoring chemical processes is essential to prevent catastrophic failures, optimize costs and profits, and ensure the safety of employees and the environment. A key component of modern monitoring systems is the automated detection of anomalies in sensor data over time, called time series, enabling partial automation of plant operation and adding additional layers of supervision to crucial components. The development of anomaly detection methods in this domain is challenging, since real chemical process data are usually proprietary, and simulated data are generally not a sufficient replacement. In this paper, we present NoBOOM, the first collection of datasets for anomaly detection in real-world chemical process data, including labeled data from a running process at our industry partner BASF SE — one of the world’s leading chemical companies — and several chemical processes run in laboratory‑scale and pilot‑scale plants. While we are not able to share every detail about the industrial process, for the laboratory‑ and pilot‑scale plants, we provide comprehensive information on plant configuration, process operation, and, in particular, anomaly events, enabling a differentiated analysis of anomaly detection methods. To demonstrate the complexity of the benchmark, we analyze the data with regard to common issues of time-series anomaly detection (TSAD) benchmarks, including potential triviality and bias.

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TMLR Journal 2023 Journal Article

TimeSeAD: Benchmarking Deep Multivariate Time-Series Anomaly Detection

Dennis Wagner
Tobias Michels
Florian C.F. Schulz
Arjun Nair
Maja Rudolph
Marius Kloft

Developing new methods for detecting anomalies in time series is of great practical significance, but progress is hindered by the difficulty of assessing the benefit of new methods, for the following reasons. (1) Public benchmarks are flawed (e.g., due to potentially erroneous anomaly labels), (2) there is no widely accepted standard evaluation metric, and (3) evaluation protocols are mostly inconsistent. In this work, we address all three issues: (1) We critically analyze several of the most widely-used multivariate datasets, identify a number of significant issues, and select the best candidates for evaluation. (2) We introduce a new evaluation metric for time-series anomaly detection, which—in contrast to previous metrics—is recall consistent and takes temporal correlations into account. (3) We analyze and overhaul existing evaluation protocols and provide the largest benchmark of deep multivariate time-series anomaly detection methods to date. We focus on deep-learning based methods and multivariate data, a common setting in modern anomaly detection. We provide all implementations and analysis tools in a new comprehensive library for Time Series Anomaly Detection, called TimeSeAD.

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