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ЖУРНАЛЫ // Buletinul Academiei de Ştiinţe a Republicii Moldova. Matematica // Архив

Bul. Acad. Ştiinţe Repub. Mold. Mat., 2003, номер 1, страницы 31–46 (Mi basm185)

Эта публикация цитируется в 10 статьях

Research articles

Quadratic systems with limit cycles of normal size

Leonid A. Cherkasa, Joan C. Artésb, Jaume Llibreb

a Belarusian State University of Informatics and Radioelectronics, Minsk, Belarus
b Departament de Matemàtiques, Universitat Autònoma de Barcelona, Barcelona, Spain

Аннотация: In the class of planar autonomous quadratic polynomial differential systems we provide 6 different phase portraits having exactly 3 limit cycles surrounding a focus, 5 of them have a unique focus. we also provide 2 different phase portraits having exactly 3 limit cycles surrounding one focus and 1 limit cycle surrounding another focus. the existence of the exact given number of limit cycles is proved using the dulac function. all limit cycles of the given systems can be detected through numerical methods; i.e. the limit cycles have “a normal size” using perko's terminology.

Ключевые слова и фразы: quadratic systems, limit cycles.

MSC: 34C07, 34C08

Поступила в редакцию: 18.10.2002

Язык публикации: английский



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