unsupervised anomaly detection
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Xian Tao ◽  
Da-Peng Zhang ◽  
Wenzhi Ma ◽  
Zhanxin Hou ◽  
Zhenfeng Lu ◽  

2022 ◽  
Vol 70 (3) ◽  
pp. 5363-5381
Amgad Muneer ◽  
Shakirah Mohd Taib ◽  
Suliman Mohamed Fati ◽  
Abdullateef O. Balogun ◽  
Izzatdin Abdul Aziz

2022 ◽  
Vol 41 (3) ◽  
pp. 1207-1222
Jin Wang ◽  
Changqing Zhao ◽  
Shiming He ◽  
Yu Gu ◽  
Osama Alfarraj ◽  

2021 ◽  
Sergio Pirla ◽  
Jordi Quoidbach

Decades of research suggest that money buys very little happiness. However, previous studies have relied on static measures assessing people’s well-being once or on average. We examine the “reel” of people’s emotional lives through over 1 million reports from 23,000 individuals whose happiness was tracked in real-time using a smartphone app. Results show that lower income is associated with increased happiness volatility—a relationship that replicates across multiple operationalizations of volatility, statistical models, and a sample of individuals from six developing countries (N > 25,000). An unsupervised anomaly detection algorithm further revealed that the greatest gap is between how frequent and intense the rich and the poor experience emotional downs, not ups. The happiness gap between the highest and lowest earners during episodes of intense unhappiness was 1.5 to 3 times the size of the gap in average happiness between these two groups. Finally, exploiting the exogeneity of monthly payments, we find that low-income people experience more moments and periods of anomalous happiness the last few days of the month, suggesting a causal relationship between income and happiness volatility.

Informatics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 85
Lucas Costa Brito ◽  
Gian Antonio Susto ◽  
Jorge Nei Brito ◽  
Marcus Antonio Viana Duarte

The monitoring of rotating machinery is an essential activity for asset management today. Due to the large amount of monitored equipment, analyzing all the collected signals/features becomes an arduous task, leading the specialist to rely often on general alarms, which in turn can compromise the accuracy of the diagnosis. In order to make monitoring more intelligent, several machine learning techniques have been proposed to reduce the dimension of the input data and also to analyze it. This paper, therefore, aims to compare the use of vibration features extracted based on machine learning models, expert domain, and other signal processing approaches for identifying bearing faults (anomalies) using machine learning (ML)—in addition to verifying the possibility of reducing the number of monitored features, and consequently the behavior of the model when working with reduced dimensionality of the input data. As vibration analysis is one of the predictive techniques that present better results in the monitoring of rotating machinery, vibration signals from an experimental bearing dataset were used. The proposed features were used as input to an unsupervised anomaly detection model (Isolation Forest) to identify bearing fault. Through the study, it is possible to verify how the ML model behaves in view of the different possibilities of input features used, and their influences on the final result in addition to the possibility of reducing the number of features that are usually monitored by reducing the dimension. In addition to increasing the accuracy of the model when extracting correct features for the application under study, the reduction in dimensionality allows the specialist to monitor in a compact way the various features collected on the equipment.

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Shicheng Li ◽  
Shumin Lai ◽  
Yan Jiang ◽  
Wenle Wang ◽  
Yugen Yi

Anomaly detection (AD) aims to distinguish the data points that are inconsistent with the overall pattern of the data. Recently, unsupervised anomaly detection methods have aroused huge attention. Among these methods, feature representation (FR) plays an important role, which can directly affect the performance of anomaly detection. Sparse representation (SR) can be regarded as one of matrix factorization (MF) methods, which is a powerful tool for FR. However, there are some limitations in the original SR. On the one hand, it just learns the shallow feature representations, which leads to the poor performance for anomaly detection. On the other hand, the local geometry structure information of data is ignored. To address these shortcomings, a graph regularized deep sparse representation (GRDSR) approach is proposed for unsupervised anomaly detection in this work. In GRDSR, a deep representation framework is first designed by extending the single layer MF to a multilayer MF for extracting hierarchical structure from the original data. Next, a graph regularization term is introduced to capture the intrinsic local geometric structure information of the original data during the process of FR, making the deep features preserve the neighborhood relationship well. Then, a L1-norm-based sparsity constraint is added to enhance the discriminant ability of the deep features. Finally, a reconstruction error is applied to distinguish anomalies. In order to demonstrate the effectiveness of the proposed approach, we conduct extensive experiments on ten datasets. Compared with the state-of-the-art methods, the proposed approach can achieve the best performance.

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