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A. Lazarov
Computer Science and Engineering Faculty, BFU, 62 San Stefano Str., 8000 Burgas, Bulgaria Aerospace Engineering Faculty K.N. Toosi University of Technology,Tehran, Iran
C. Minchev
Technical Faculty Shumen University, 115 Universitetska Str., 9700 Shumen, Bulgaria Electrical Engineering Department, Seoul National University,Seoul, Korea Republic of