1. Professor, Institute of Mechanics, National Academy of Sciences of Armenia, Yerevan 0019, Republic of Armenia.
2. Associate Professor, Institute of Mechanics, National Academy of Sciences of Armenia, Yerevan 0019, Republic of Armenia.
3. Associate Professor, Dept. of Mechanical and Aeronautical Engineering, Clarkson Univ., Potsdam, NY 13699 (corresponding author).