scholarly journals Darboux integrability of a cubic differential system with two parallel invariant straight lines

2021 ◽  
Vol 38 (1) ◽  
pp. 129-137
Author(s):  
DUMITRU COZMA ◽  

In this paper we prove the Darboux integrability of a cubic differential system with a singular point of a center typer having at least two parallel invariant straight lines.

2013 ◽  
Vol 22 (2) ◽  
pp. 185-192
Author(s):  
DUMITRU COZMA ◽  

For cubic differential system with a singular point O(0, 0) of a center or a focus type having three invariant straight lines of which one is 2-invariant it is proved that the origin is a center if and only if the first five Lyapunov quantities vanish.


2001 ◽  
Vol 11 (01) ◽  
pp. 197-206 ◽  
Author(s):  
H. S. Y. CHAN ◽  
K. W. CHUNG ◽  
DONGWEN QI

Concrete numerical examples of quadratic differential systems having three limit cycles surrounding one singular point are shown. In case another finite singular point also exists, a (3, 1) distribution of limit cycles is also obtained. This is the highest number of limit cycles known to occur in a quadratic differential system so far. Representative bifurcation diagrams are drawn for realistic parameter values.


2020 ◽  
Vol 135 ◽  
pp. 109712
Author(s):  
Adnan A. Jalal ◽  
Azad I. Amen ◽  
Nejmaddin A. Sulaiman

2020 ◽  
Vol 8 (2) ◽  
pp. 6-13
Author(s):  
D. Cozma ◽  
A. Matei

We find conditions for a singular point O(0, 0) of a center or a focus type to be a center, in a cubic differential system with one irreducible invariant cubic. The presence of a center at O(0, 0) is proved by constructing integrating factors.


2020 ◽  
Vol 56 ◽  
pp. 63-78
Author(s):  
I.N. Sergeev

For a singular point of an autonomous differential system, the natural concepts of its Perron and upper-limit stability are defined, reminiscent of Lyapunov stability. Numerous varieties of them are introduced: from asymptotic and global stability to complete and total instability. Their logical connections with each other are investigated: cases of their coincidence are revealed and examples of their possible differences are given. The invariance of most of these properties with respect to the narrowing of the phase region of the system is established.


1972 ◽  
Vol 18 (2) ◽  
pp. 93-98 ◽  
Author(s):  
W. A. Harris

The linear differential systemwhere w is a vector with n components and A is an n by n matrix is said to have z = 0 as a regular singular point if there exists a fundamental matrix of the formsuch that S is holomorphic at z = 0 and R is a constant matrix ((1), p. 111; (2), p. 73). For such systems A will have at most a pole at z = 0 and we may writewhere p is an integer, Ã is holomorphic at z = 0, and Ã(0) ≠ 0. However, the converse is not true. When p ≦ − 1, A is holomorphic at z = 0, and every fundamental matrix is holomorphic at z = 0. If p ≧ 1, the non-negative integer p is called (after Poincaré) the rank of the singularity and there is a significant difference between the cases p = 0 and p ≧ 1. If p = 0 the linear differential system (1) is known to have z = 0 as a regular singular point ((1), p. 111) ; whereas, if p ≧ 1, z = 0 may or may not be a regular singular point.


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