1. Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam
2. Faculty of Natural Sciences, Duy Tan University, Da Nang 550000, Vietnam
3. Department of Mathematics and Informatics, J. Selye University, Komarno, Slovakia
4. Faculty of Electrical and Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam