S.M. Mikhailov (Yandush) distinguished two ethnographic groups and two dialects of the Chuvash ethnos. The scientist attributed the population of Kozmodemyansky and the northern part of Yadrinsky uyezds to the upper (Virjal) Chuvash, and that of Tsivisky and Cheboksary uyezds of Kazan province – to the lower (Anatri) ones. Starting with the works of G.I. Komissarov, a third (middle-level) group began to be allocated from the lower group. According to the scientist, the Chuvash, being a separate community of Turkic-speaking peoples, used to live in Zakamye, where they had migrated from Siberia. He developed the Turkic-Bulgarian theory of the Chuvash language origin and the main ethnographic groups (middle lower and lower) of the Chuvash ethnos. He considered the upper dialect to be a mixed group, in whose culture, in addition to Turkic-Bulgar elements he found many elements of the Finno-Ugrians (the mountain Mari and the Mordvins-Erzya), and partly Kazan Tatars. Prior to annexation of the Chuvash Region to the Moscow state, two ethnographic groups of the mountain Chuvash functioned on the right bank of the Volga – the upper and the middle lower. After settling the southern steppe regions, in the process of cultural dialogue with the Mishar Tatars, a third ethnographic group was formed, known to the middle lower Chuvash as the khirti “steppe”. In Modern times, the geographical location of the ethnographic groups of the Chuvash ethnos contributed to penetration of the ideas of the European-Russian Enlightenment in the Chuvash Region (from the western territories to the eastern and southern ones). In the 1950s of the XX century the ideas of the Chuvash enlightenment were first formulated by S.M. Mikhailov, and later they began to spread in the academic circles of the entire Volga region. His works remain a valuable source for identifying the adaptive scheme of the ethnos, which the Chuvash built by localizing the “evil” principle outside of themselves, their society, ethnos.
A Frequency Adaptive Scheme Based on Newton Structure of PRRC for LCL-Type Inverter Connected with Weak Grid
