A novel item anomaly detection approach against shilling attacks in collaborative recommendation systems using the dynamic time interval segmentation technique

2015 ◽  
Vol 306 ◽  
pp. 150-165 ◽  
Author(s):  
Hui Xia ◽  
Bin Fang ◽  
Min Gao ◽  
Hui Ma ◽  
Yuanyan Tang ◽  
...  
2018 ◽  
Vol 14 (10) ◽  
pp. 155014771880330 ◽  
Author(s):  
Li Cheng ◽  
Yijie Wang ◽  
Yong Zhou ◽  
Xingkong Ma

Due to the increasing arriving rate and complex relationship of behavior data streams, how to detect sequential behavior anomaly in an efficient and accurate manner has become an emerging challenge. However, most of the existing literature simply calculates the anomaly score for segmented sequence, and there is limited work going deep to investigate data stream segment and structural relationship. Moreover, existing studies cannot meet efficiency requirements because of large number of projected subsequences. In this article, we propose EADetection, an efficient and accurate sequential behavior anomaly detection approach over data streams. EADetection adopts time interval and fuzzy logic–based correlation to segment event stream adaptively based on rolling window. Through dynamic projection space–based fast pruning, large number of repeated patterns are reduced to improve detection efficiency. Meanwhile, EADetection calculates the anomaly score by top-k pattern–based abnormal scoring based on directed loop graph–based storage strategy, which ensures the accuracy of detection. Specially, we design and implement a streaming anomaly detection system based on EADetection to perform real-time detection. Extensive experiments confirm that EADetection can achieve real time and improve accuracy, significantly reduces latency by 36.8% and reduces false positive rate by 6.4% compared with existing approach.


2021 ◽  
Vol 13 (4) ◽  
pp. 721
Author(s):  
Zhongheng Li ◽  
Fang He ◽  
Haojie Hu ◽  
Fei Wang ◽  
Weizhong Yu

Collaborative representation-based detector (CRD), as the most representative anomaly detection method, has been widely applied in the field of hyperspectral anomaly detection (HAD). However, the sliding dual window of the original CRD introduces high computational complexity. Moreover, most HAD models only consider a single spectral or spatial feature of the hyperspectral image (HSI), which is unhelpful for improving detection accuracy. To solve these problems, in terms of speed and accuracy, we propose a novel anomaly detection approach, named Random Collective Representation-based Detector with Multiple Feature (RCRDMF). This method includes the following steps. This method first extract the different features include spectral feature, Gabor feature, extended multiattribute profile (EMAP) feature, and extended morphological profile (EMP) feature matrix from the HSI image, which enables us to improve the accuracy of HAD by combining the multiple spectral and spatial features. The ensemble and random collaborative representation detector (ERCRD) method is then applied, which can improve the anomaly detection speed. Finally, an adaptive weight approach is proposed to calculate the weight for each feature. Experimental results on six hyperspectral datasets demonstrate that the proposed approach has the superiority over accuracy and speed.


2021 ◽  
pp. 1-17
Author(s):  
Fátima Leal ◽  
Bruno Veloso ◽  
Benedita Malheiro ◽  
Juan Carlos Burguillo ◽  
Adriana E. Chis ◽  
...  

Explainable recommendations enable users to understand why certain items are suggested and, ultimately, nurture system transparency, trustworthiness, and confidence. Large crowdsourcing recommendation systems ought to crucially promote authenticity and transparency of recommendations. To address such challenge, this paper proposes the use of stream-based explainable recommendations via blockchain profiling. Our contribution relies on chained historical data to improve the quality and transparency of online collaborative recommendation filters – Memory-based and Model-based – using, as use cases, data streamed from two large tourism crowdsourcing platforms, namely Expedia and TripAdvisor. Building historical trust-based models of raters, our method is implemented as an external module and integrated with the collaborative filter through a post-recommendation component. The inter-user trust profiling history, traceability and authenticity are ensured by blockchain, since these profiles are stored as a smart contract in a private Ethereum network. Our empirical evaluation with HotelExpedia and Tripadvisor has consistently shown the positive impact of blockchain-based profiling on the quality (measured as recall) and transparency (determined via explanations) of recommendations.


2013 ◽  
Vol 49 (3) ◽  
pp. 688-697 ◽  
Author(s):  
Ismail Sengor Altingovde ◽  
Özlem Nurcan Subakan ◽  
Özgür Ulusoy

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