Affiliation: | a Institute of Technical Acoustics, National Academy of Sciences of Belarus, 13 Ludnikov Av., Vitebsk 210023, Belarusb Institute of Electronic and Information Systems, Novgorod State University, 41 B. S. Peterburgskaya St., Veliky Novgorod 173003, Russiac Physics Department, Oakland University, Rochester, MI 48309, USA |