o:20837 Plasma channel evolution in the triggered lightning discharges doctoral dissertation Еволуција плазма канала код тригерованих атмосферских пражњена : докторска дисертација en Plasma channel evolution is of fundamental interest for the study of the lightning physics, the electrodynamics of the atmosphere and for electrical engineering practice. The subject of this dissertation is the development of detailed and efficient numerical algorithms for application in the study of the lightning channel evolution. First off all, the classical numerical methods for the calculating the three - dimensional integrals were used to calculate the axial electric field along the lightning channel axis. The results measurement of the negative triggered lightning discharge have been used as input parameters during calculation. Different engineering models were used in the calculation - the TL, the MTLE, the MTLP, the MTLE and the GTCS model. Obtained results for electric field as well as the point form of Ohm’s law have been used to calculate the profile of longitudinal electrical conductivity on the lightning channel. The comparison with the experimental results was performed. It has been shown that the mean values of the mentioned physical quantities are in accordance with the experimental results. On the basis of the experimental results and semi-empirical formulas, other essential parameters of the lightning channel (the concentration and the temperature of the carriers) can be estimated. After a detailed overview of all methods used in the literature to study the lightning channel dynamics, the decision was to use the GTCS model. For this purpose, it is necessary to precisely calculate the channel discharge function from Volterra integral equation of the first kind. This equation is solved analytically by Laplace transformation, as well as by the convolution quadrature method (CQ method). The Volterra equation is also solved by the modified composite trapezoidal formula method (MCTF method), which is one of the numerical methods used to provide a very high degree of accuracy with minimal approximations. Results showed excellent agreement with the analytical method. Obtained channel discharge function is used in the calculations of other physical parameters along radial and axial directions of the channel. Based on the afore stated results, the guidelines for further study of the lightning channel dynamics are given. Еволуција канала је од базичног значаја за проучавање физик канала муње, електродинамика атмосфере као и за електроинжењерску праксу. Циљ ове дисертације је развој детаљних аналитичких и нумеричких алгоритама. Electrical and Computer Engineering - Plasma physics / Електротехника и рачунарство - Физика плазме Datum odbrane: 5. 9. 2019. electric field, electric conductivity, lightning channel dynamic, Volterraintegral equation, analytical methods, Laplace transform, convolution quadrature,numerical methods електрична проводност, динамика канала муње, Волтерина интегрална једначина, Лапласова трансформација, конволуционе квадратуре yes 51823119 91552101 7151 91552100 51823119 2020-01-23T13:02:17.053Z 45 no 46 mentor Dragan, 1988- 26984807 Pavlović 2019 63 mentor Jovan, 1962- 12587623 Cvetić 2019 63 član komisije Tomislav, 1965- 12705383 Šekara 2019 63 član komisije Milorad, 1960- 14052967 Kuraica 2019 63 član komisije Gradimir V., 1948- 13802343 Milovanović 2019 63 član komisije Branko 1958- 701690 Kolundžija 2019 163 lista 10683315 http://phaidrabg.bg.ac.rs/o:20837 no yes 4 2020-01-23T13:02:17.320Z 70 11 1067197 1067243 11 1066732 1066763 electric field, electric conductivity, lightning channel dynamic, Volterraintegral equation, analytical methods, Laplace transform, convolution quadrature,numerical methods електрична проводност, динамика канала муње, Волтерина интегрална једначина, Лапласова трансформација, конволуционе квадратуре 621.3.011:537.52(043.3) 1738 11A04 2019