379 research outputs found
Spot The Odd One Out: Regularized Complete Cycle Consistent Anomaly Detector GAN
This study presents an adversarial method for anomaly detection in real-world
applications, leveraging the power of generative adversarial neural networks
(GANs) through cycle consistency in reconstruction error. Previous methods
suffer from the high variance between class-wise accuracy which leads to not
being applicable for all types of anomalies. The proposed method named RCALAD
tries to solve this problem by introducing a novel discriminator to the
structure, which results in a more efficient training process. Additionally,
RCALAD employs a supplementary distribution in the input space to steer
reconstructions toward the normal data distribution, effectively separating
anomalous samples from their reconstructions and facilitating more accurate
anomaly detection. To further enhance the performance of the model, two novel
anomaly scores are introduced. The proposed model has been thoroughly evaluated
through extensive experiments on six various datasets, yielding results that
demonstrate its superiority over existing state-of-the-art models. The code is
readily available to the research community at
https://github.com/zahraDehghanian97/RCALAD.Comment: under revision of Applied Soft Computing Journa
Adversarially Learned Anomaly Detection on CMS Open Data: re-discovering the top quark
We apply an Adversarially Learned Anomaly Detection (ALAD) algorithm to the
problem of detecting new physics processes in proton-proton collisions at the
Large Hadron Collider. Anomaly detection based on ALAD matches performances
reached by Variational Autoencoders, with a substantial improvement in some
cases. Training the ALAD algorithm on 4.4 fb-1 of 8 TeV CMS Open Data, we show
how a data-driven anomaly detection and characterization would work in real
life, re-discovering the top quark by identifying the main features of the
t-tbar experimental signature at the LHC.Comment: 16 pages, 9 figure
Text Anomaly Detection with ARAE-AnoGAN
Generative adversarial networks (GANs) are now one of the key techniques for detecting anomalies in images, yielding remarkable results. Applying similar methods to discrete structures, such as text sequences, is still largely an unknown. In this work, we introduce a new GAN-based text anomaly detection method, called ARAE-AnoGAN, that trains an adversarially regularized autoencoder (ARAE) to reconstruct normal sentences and detects anomalies via a combined anomaly score based on the building blocks of ARAE. Finally, we present experimental results demonstrating the effectiveness of ARAE-AnoGAN and other deep learning methods in text anomaly detection
Targeted collapse regularized autoencoder for anomaly detection: black hole at the center
Autoencoders have been extensively used in the development of recent anomaly
detection techniques. The premise of their application is based on the notion
that after training the autoencoder on normal training data, anomalous inputs
will exhibit a significant reconstruction error. Consequently, this enables a
clear differentiation between normal and anomalous samples. In practice,
however, it is observed that autoencoders can generalize beyond the normal
class and achieve a small reconstruction error on some of the anomalous
samples. To improve the performance, various techniques propose additional
components and more sophisticated training procedures. In this work, we propose
a remarkably straightforward alternative: instead of adding neural network
components, involved computations, and cumbersome training, we complement the
reconstruction loss with a computationally light term that regulates the norm
of representations in the latent space. The simplicity of our approach
minimizes the requirement for hyperparameter tuning and customization for new
applications which, paired with its permissive data modality constraint,
enhances the potential for successful adoption across a broad range of
applications. We test the method on various visual and tabular benchmarks and
demonstrate that the technique matches and frequently outperforms alternatives.
We also provide a theoretical analysis and numerical simulations that help
demonstrate the underlying process that unfolds during training and how it can
help with anomaly detection. This mitigates the black-box nature of
autoencoder-based anomaly detection algorithms and offers an avenue for further
investigation of advantages, fail cases, and potential new directions.Comment: 16 pages, 4 figures, 4 table
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