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To detect anomalies with precision and without prior knowledge in time series, is it better to build a detector from the initial temporal representation, or to compute a new (tabular) representation using an existing automatic variable…

Machine Learning · Computer Science 2025-01-22 Marine Hamon , Vincent Lemaire , Nour Eddine Yassine Nair-Benrekia , Samuel Berlemont , Julien Cumin

Anomaly detection is a fundamental problem in domains such as healthcare, manufacturing, and cybersecurity. This thesis proposes new unsupervised methods for anomaly detection in both structured and streaming data settings. In the first…

Machine Learning · Computer Science 2025-05-20 Filippo Leveni

Unsupervised fault detection in multivariate time series plays a vital role in ensuring the stable operation of complex systems. Traditional methods often assume that normal data follow a single Gaussian distribution and identify anomalies…

Machine Learning · Computer Science 2025-07-01 Hong Liu , Xiuxiu Qiu , Yiming Shi , Miao Xu , Zelin Zang , Zhen Lei

Monitoring complex systems results in massive multivariate time series data, and anomaly detection of these data is very important to maintain the normal operation of the systems. Despite the recent emergence of a large number of anomaly…

Machine Learning · Computer Science 2021-06-14 Liwei Deng , Xuanhao Chen , Yan Zhao , Kai Zheng

Unsupervised anomaly detection of multivariate time series is a challenging task, given the requirements of deriving a compact detection criterion without accessing the anomaly points. The existing methods are mainly based on reconstruction…

Machine Learning · Computer Science 2026-05-26 Qingxiang Liu , Xiaoliang Luo , Chenghao Liu , Sheng Sun , Di Yao , Lvchun Wang , Wei Yu , Yuxuan Liang

Detection of periodic patterns of interest within noisy time series data plays a critical role in various tasks, spanning from health monitoring to behavior analysis. Existing learning techniques often rely on labels or clean versions of…

Machine Learning · Computer Science 2025-06-24 Berken Utku Demirel , Christian Holz

In one-class-learning tasks, only the normal case (foreground) can be modeled with data, whereas the variation of all possible anomalies is too erratic to be described by samples. Thus, due to the lack of representative data, the…

Computer Vision and Pattern Recognition · Computer Science 2019-06-03 Duc Tam Nguyen , Zhongyu Lou , Michael Klar , Thomas Brox

Detecting anomalies in high-dimensional, time-dependent simulation data is challenging due to complex spatial and temporal dynamics. We study reconstruction-based anomaly detection for ensemble data from parameterized K\'arm\'an vortex…

Machine Learning · Computer Science 2026-01-14 Hamid Gadirov , Martijn Westra , Steffen Frey

Using a convGRU-based autoencoder, this thesis proposes a framework to learn spatial-temporal aspects of raw network traffic in an unsupervised and protocol-agnostic manner. The learned representations are used to measure the effect on the…

Machine Learning · Computer Science 2022-05-19 Fabian Kopp

Industrial process monitoring increasingly relies on sensor-generated time-series data, yet the lack of labels, high variability, and operational noise make it difficult to extract meaningful patterns using conventional methods. Existing…

Machine Learning · Computer Science 2025-11-18 Zhipeng Ma , Bo Nørregaard Jørgensen , Zheng Grace Ma

The demand for high-performance anomaly detection techniques of IoT data becomes urgent, especially in industry field. The anomaly identification and explanation in time series data is one essential task in IoT data mining. Since that the…

Databases · Computer Science 2021-01-06 Xiaoou Ding , Hongzhi Wang , Chen Wang , Zijue Li , Zheng Liang

We introduce an anomaly detection method for multivariate time series data with the aim of identifying critical periods and features influencing extreme climate events like snowmelt in the Arctic. This method leverages the Variational…

Machine Learning · Computer Science 2024-07-16 Tolulope Ale , Nicole-Jeanne Schlegel , Vandana P. Janeja

Time-series anomaly detection, which detects errors and failures in a workflow, is one of the most important topics in real-world applications. The purpose of time-series anomaly detection is to reduce potential damages or losses. However,…

Machine Learning · Computer Science 2025-04-17 Jinsung Jeon , Jaehyeon Park , Sewon Park , Jeongwhan Choi , Minjung Kim , Noseong Park

Given high-dimensional time series data (e.g., sensor data), how can we detect anomalous events, such as system faults and attacks? More challengingly, how can we do this in a way that captures complex inter-sensor relationships, and…

Machine Learning · Computer Science 2021-06-15 Ailin Deng , Bryan Hooi

Anomaly detection is critical in various fields, including intrusion detection, health monitoring, fault diagnosis, and sensor network event detection. The isolation forest (or iForest) approach is a well-known technique for detecting…

Machine Learning · Computer Science 2021-10-06 Seemandhar Jain , Prarthi Jain , Abhishek Srivastava

One of the critical factors that drive the economic development of a country and guarantee the sustainability of its industries is the constant availability of electricity. This is usually provided by the national electric grid. However, in…

The early and robust detection of anomalies occurring in discrete manufacturing processes allows operators to prevent harm, e.g. defects in production machinery or products. While current approaches for data-driven anomaly detection provide…

Machine Learning · Computer Science 2021-01-05 Benjamin Maschler , Thi Thu Huong Pham , Michael Weyrich

As large-scale time-series data can easily be found in real-world applications, multivariate time-series anomaly detection has played an essential role in diverse industries. It enables productivity improvement and maintenance cost…

Machine Learning · Computer Science 2022-02-22 Heejeong Choi , Subin Kim , Pilsung Kang

Subsequence-based time series classification algorithms provide accurate and interpretable models, but training these models is extremely computation intensive. The asymptotic time complexity of subsequence-based algorithms remains a…

Machine Learning · Computer Science 2021-02-18 Atif Raza , Stefan Kramer

Detecting anomalies over real-world datasets remains a challenging task. Data annotation is an intensive human labor problem, particularly in sequential datasets, where the start and end time of anomalies are not known. As a result, data…

Machine Learning · Computer Science 2022-10-05 Parastoo Kamranfar , David Lattanzi , Amarda Shehu , Daniel Barbará