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We present a new framework to detect various types of variable objects within massive astronomical time-series data. Assuming that the dominant population of objects is non-variable, we find outliers from this population by using a…

Instrumentation and Methods for Astrophysics · Physics 2010-01-17 Min-Su Shin , Michael Sekora , Yong-Ik Byun

In this work, we propose a new, fast and scalable method for anomaly detection in large time-evolving graphs. It may be a static graph with dynamic node attributes (e.g. time-series), or a graph evolving in time, such as a temporal network.…

Social and Information Networks · Computer Science 2019-01-29 Volodymyr Miz , Benjamin Ricaud , Kirell Benzi , Pierre Vandergheynst

We introduce a new semi-supervised, time series anomaly detection algorithm that uses deep reinforcement learning (DRL) and active learning to efficiently learn and adapt to anomalies in real-world time series data. Our model - called RLAD…

Machine Learning · Computer Science 2021-04-02 Tong Wu , Jorge Ortiz

We consider two-state Non-Homogeneous Hidden Markov Models (NHHMMs) for forecasting univariate time series. Given a set of predictors, the time series are modeled via predictive regressions with state dependent coefficients and time-varying…

Methodology · Statistics 2019-07-31 Constandina Koki , Loukia Meligkotsidou , Ioannis Vrontos

Detecting out of distribution (OOD) samples is of paramount importance in all Machine Learning applications. Deep generative modeling has emerged as a dominant paradigm to model complex data distributions without labels. However, prior work…

Machine Learning · Computer Science 2021-01-05 Gowthami Somepalli , Yexin Wu , Yogesh Balaji , Bhanukiran Vinzamuri , Soheil Feizi

Hidden Quantum Markov Models (HQMMs) can be thought of as quantum probabilistic graphical models that can model sequential data. We extend previous work on HQMMs with three contributions: (1) we show how classical hidden Markov models…

Machine Learning · Statistics 2017-10-26 Siddarth Srinivasan , Geoff Gordon , Byron Boots

Anomaly detection suffered from the lack of anomalies due to the diversity of abnormalities and the difficulties of obtaining large-scale anomaly data. Semi-supervised anomaly detection methods are often used to solely leverage normal data…

Computer Vision and Pattern Recognition · Computer Science 2023-04-11 Jian Shi , Ni Zhang

Pulsar timing experiments typically generate a phase-connected timing solution from a sequence of times-of-arrival (TOAs) by absolute pulse numbering, i.e. by fitting an integer number of pulses between TOAs in order to minimize the…

High Energy Astrophysical Phenomena · Physics 2020-06-24 A. Melatos , L. M. Dunn , S. Suvorova , W. Moran , R. J. Evans

This paper proposes to use set features for detecting anomalies in samples that consist of unusual combinations of normal elements. Many leading methods discover anomalies by detecting an unusual part of a sample. For example,…

Computer Vision and Pattern Recognition · Computer Science 2025-03-20 Niv Cohen , Issar Tzachor , Yedid Hoshen

Anomaly detection is to recognize samples that differ in some respect from the training observations. These samples which do not conform to the distribution of normal data are called outliers or anomalies. In real-world anomaly detection…

Computer Vision and Pattern Recognition · Computer Science 2022-07-05 Vahid Reza Khazaie , Anthony Wong , Yalda Mohsenzadeh

Google uses continuous streams of data from industry partners in order to deliver accurate results to users. Unexpected drops in traffic can be an indication of an underlying issue and may be an early warning that remedial action may be…

Machine Learning · Statistics 2017-08-15 Dominique T. Shipmon , Jason M. Gurevitch , Paolo M. Piselli , Stephen T. Edwards

With the rapid development of multi-cloud environments, it is increasingly important to ensure the security and reliability of intelligent monitoring systems. In this paper, we propose an anomaly detection and early warning mechanism for…

Machine Learning · Computer Science 2025-06-10 Yihong Jin , Ze Yang , Juntian Liu , Xinhe Xu

Data-driven anomaly detection methods suffer from the drawback of detecting all instances that are statistically rare, irrespective of whether the detected instances have real-world significance or not. In this paper, we are interested in…

Machine Learning · Statistics 2018-03-08 Elizabeth Hou , Kumar Sricharan , Alfred O. Hero

Detecting unusual patterns in graph data is a crucial task in data mining. However, existing methods face challenges in consistently achieving satisfactory performance and often lack interpretability, which hinders our understanding of…

Machine Learning · Computer Science 2024-06-28 Yifei Yang , Peng Wang , Xiaofan He , Dongmian Zou

Detecting anomalies in data is a vital task, with numerous high-impact applications in areas such as security, finance, health care, and law enforcement. While numerous techniques have been developed in past years for spotting outliers and…

Social and Information Networks · Computer Science 2014-04-29 Leman Akoglu , Hanghang Tong , Danai Koutra

Graph-level anomaly detection aims to identify anomalous graphs or subgraphs within graph datasets, playing a vital role in various fields such as fraud detection, review classification, and biochemistry. While Graph Neural Networks (GNNs)…

Machine Learning · Computer Science 2025-10-10 Liting Li , Yumeng Wang , Yueheng Sun

The use of in-situ digital sensors for water quality monitoring is becoming increasingly common worldwide. While these sensors provide near real-time data for science, the data are prone to technical anomalies that can undermine the…

The sophistication and diversity of contemporary cyberattacks have rendered the use of proxies, gateways, firewalls, and encrypted tunnels as a standalone defensive strategy inadequate. Consequently, the proactive identification of data…

Machine Learning · Computer Science 2024-09-24 Liyang Wang , Yu Cheng , Hao Gong , Jiacheng Hu , Xirui Tang , Iris Li

Graph anomaly detection is a popular and vital task in various real-world scenarios, which has been studied for several decades. Recently, many studies extending deep learning-based methods have shown preferable performance on graph anomaly…

Machine Learning · Computer Science 2025-05-13 Jing Ren , Mingliang Hou , Zhixuan Liu , Xiaomei Bai

The complexity and ubiquity of modern computing systems is a fertile ground for anomalies, including security and privacy breaches. In this paper, we propose a new methodology that addresses the practical challenges to implement anomaly…

Cryptography and Security · Computer Science 2020-06-17 Charles F. Gonçalves , Daniel S. Menasché , Alberto Avritzer , Nuno Antunes , Marco Vieira