1. Department of Civil Engineering, University of Thessaly, Volos, Greece
2. Department of Mathematics, Jadavpur University, Kolkata, 700092 West Bengal, India
3. Department of Physics, Government College of Engineering and Ceramic Technology, Kolkata, 700010 West Bengal, India
4. Department of Physics, Indian Institute of Science, Bangalore 560012, India
5. Institute of Physics, Southern Federal University, 194 Stachki, Rostov-on-Don 344090, Russia