1. Ilia Vekua Institute of Applied Mathematics, Ivane Javakhishvili Tbilisi State University, 2 University Str., 0186; and Georgian Technical University, 77 Kostava Str., 0175Tbilisi, Georgia
2. Ilia Vekua Institute of Applied Mathematics, Ivane Javakhishvili Tbilisi State University, 2 University Str., 0186; Georgian Technical University, 77 Kostava Str., 0175Tbilisi, Georgia; and Electromagnetic Compatibility Laboratory, Missouri University of Science and Technology, 4000 Enterprise Drive 65409, Rolla, MO, USA