21,492 research outputs found
One-Class Classification: Taxonomy of Study and Review of Techniques
One-class classification (OCC) algorithms aim to build classification models
when the negative class is either absent, poorly sampled or not well defined.
This unique situation constrains the learning of efficient classifiers by
defining class boundary just with the knowledge of positive class. The OCC
problem has been considered and applied under many research themes, such as
outlier/novelty detection and concept learning. In this paper we present a
unified view of the general problem of OCC by presenting a taxonomy of study
for OCC problems, which is based on the availability of training data,
algorithms used and the application domains applied. We further delve into each
of the categories of the proposed taxonomy and present a comprehensive
literature review of the OCC algorithms, techniques and methodologies with a
focus on their significance, limitations and applications. We conclude our
paper by discussing some open research problems in the field of OCC and present
our vision for future research.Comment: 24 pages + 11 pages of references, 8 figure
Probing Convolutional Neural Networks for Event Reconstruction in {\gamma}-Ray Astronomy with Cherenkov Telescopes
A dramatic progress in the field of computer vision has been made in recent
years by applying deep learning techniques. State-of-the-art performance in
image recognition is thereby reached with Convolutional Neural Networks (CNNs).
CNNs are a powerful class of artificial neural networks, characterized by
requiring fewer connections and free parameters than traditional neural
networks and exploiting spatial symmetries in the input data. Moreover, CNNs
have the ability to automatically extract general characteristic features from
data sets and create abstract data representations which can perform very
robust predictions. This suggests that experiments using Cherenkov telescopes
could harness these powerful machine learning algorithms to improve the
analysis of particle-induced air-showers, where the properties of primary
shower particles are reconstructed from shower images recorded by the
telescopes. In this work, we present initial results of a CNN-based analysis
for background rejection and shower reconstruction, utilizing simulation data
from the H.E.S.S. experiment. We concentrate on supervised training methods and
outline the influence of image sampling on the performance of the CNN-model
predictions.Comment: 8 pages, 4 figures, Proceedings of the 35th International Cosmic Ray
Conference (ICRC 2017), Busan, Kore
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