1. Department of Mathematics, COMSATS Institute of Information Technology, Kamra Road, Attock 43600, Pakistan;
2. Dipartimento di Ingegneria, Università degli Studi di Napoli “Parthenope,” Centro Direzionale, Isola C4, Napoli 80143, Italy e-mail:
3. Institute of Applied Mathematics (LSIII), TU Dortmund, Vogelpothsweg 87, Dortmund D-44221, Germany
4. Department of Mathematics, University of Dhaka, Dhaka 1000, Bangladesh
5. Department of Mechanical and Civil Engineering, Purdue University Northwest, Westville, IN 46391