A taxonomy framework for unsupervised outlier detection techniques for multi-type data sets

The term "outlier" can generally be defined as an observation that is significantly different from the other values in a data set. The outliers may be instances of error or indicate events. The task of outlier detection aims at identifying such outliers in order to improve the analysis of data and further discover interesting and useful knowledge about unusual events within numerous applications domains. In this paper, we report on contemporary unsupervised outlier detection techniques for multiple types of data sets and provide a comprehensive taxonomy framework and two decision trees to select the most suitable technique based on data set. Furthermore, we highlight the advantages, disadvantages and performance issues of each class of outlier detection techniques under this taxonomy framework

Spectral Embedding Norm: Looking Deep into the Spectrum of the Graph Laplacian

The extraction of clusters from a dataset which includes multiple clusters and a significant background component is a non-trivial task of practical importance. In image analysis this manifests for example in anomaly detection and target detection. The traditional spectral clustering algorithm, which relies on the leading $K$ eigenvectors to detect $K$ clusters, fails in such cases. In this paper we propose the {\it spectral embedding norm} which sums the squared values of the first $I$ normalized eigenvectors, where $I$ can be significantly larger than $K$. We prove that this quantity can be used to separate clusters from the background in unbalanced settings, including extreme cases such as outlier detection. The performance of the algorithm is not sensitive to the choice of $I$, and we demonstrate its application on synthetic and real-world remote sensing and neuroimaging datasets

Enhance density peak clustering algorithm for anomaly intrusion detection system

In this paper proposed new model of Density Peak Clustering algorithm to enhance clustering of intrusion attacks. The Anomaly Intrusion Detection System (AIDS) by using original density peak clustering algorithm shows the stable in result to be applied to data-mining module of the intrusion detection system. The proposed system depends on two objectives; the first objective is to analyzing the disadvantage of DPC; however, we propose a novel improvement of DPC algorithm by modifying the calculation of local density method based on cosine similarity instead of the cat off distance parameter to improve the operation of selecting the peak points. The second objective is using the Gaussian kernel measure as a distance metric instead of Euclidean distance to improve clustering of high-dimensional complex nonlinear inseparable network traffic data and reduce the noise. The experimentations evaluated with NSL-KDD dataset