Walid Atwa

Work place: Computer Science Dept. Faculty of Computers and Information, Menoufia University, Egypt

E-mail: walid.atwa@ci.menofia.edu.eg


Research Interests: Data Mining, Machine Learning


Walid Atwa received the B.Sc. and M.Sc. in Computer Science from Menoufia University, Faculty of computers and information in 2006 and 2010, respectively, received his Ph.D. in Computer Science from Beijing Institute of Technology, China. His research interests are data mining and machine learning.

Author Articles
Genetic-based Summarization for Local Outlier Detection in Data Stream

By Mohamed Sakr Walid Atwa Arabi Keshk

DOI: https://doi.org/10.5815/ijisa.2021.01.05, Pub. Date: 8 Feb. 2021

Outlier detection is one of the important tasks in data mining. Detecting outliers over streaming data has become an important task in many applications, such as network analysis, fraud detections, and environment monitoring. One of the well-known outlier detection algorithms called Local Outlier Factor (LOF). However, the original LOF has many drawbacks that can’t be used with data streams: 1- it needs a lot of processing power (CPU) and large memory to detect the outliers. 2- it deals with static data which mean that in any change in data the LOF recalculates the outliers from the beginning on the whole data. These drawbacks make big challenges for existing outlier detection algorithms in terms of their accuracies when they are implemented in the streaming environment. In this paper, we propose a new algorithm called GSILOF that focuses on detecting outliers from data streams using genetics. GSILOF solve the problem of large memory needed as it has fixed memory bound. GSILOF has two phases. First, the summarization phase that tries to summarize the past data arrived. Second, the detection phase detects the outliers from the new arriving data. The summarization phase uses a genetic algorithm to try to find the subset of points that can represent the whole original set. our experiments have been done over real datasets. Our experiments confirming the effectiveness of the proposed approach and the high quality of approximate solutions in a set of real-world streaming data.

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Active Selection Constraints for Semi-supervised Clustering Algorithms

By Walid Atwa Abdulwahab Ali Almazroi

DOI: https://doi.org/10.5815/ijitcs.2020.06.03, Pub. Date: 8 Dec. 2020

Semi.-supervised clustering algorithms aim to enhance the performance of clustering using the pairwise constraints. However, selecting these constraints randomly or improperly can minimize the performance of clustering in certain situations and with different applications. In this paper, we select the most informative constraints to improve semi-supervised clustering algorithms. We present an active selection of constraints, including active must.-link (AML) and active cannot.-link (ACL) constraints. Based on Radial-Bases Function, we compute lower-bound and upper-bound between data points to select the constraints that improve the performance. We test the proposed algorithm with the base-line methods and show that our proposed active pairwise constraints outperform other algorithms.

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