Uniqueness of Limit Cycle for the Quadratic Systems with Weak Saddle and Focus

2004 ◽  
Vol 20 (4) ◽  
pp. 647-652 ◽  
Author(s):  
Shen Qi Zhao ◽  
Ping Guang Zhang
1988 ◽  
Vol 38 (1) ◽  
pp. 1-10 ◽  
Author(s):  
W. A. Coppel

It is shown that a quadratic system with a degenerate critical point has at most one limit cycle.


1989 ◽  
Vol 112 (1-2) ◽  
pp. 113-134 ◽  
Author(s):  
Colin Christopher

SynopsisThe class of quadratic systems having a parabola composed of integral curves is examined. Canonical forms are found for the members of this class, and conditions are obtained, using the Bendixson's Criterion and the Poincaré–Bendixson Theorem, for the existence or non-existence of limit cycles, in the case where there is a limit cycle “inside” the parabola (that is, in the convex component of its compliment).


1991 ◽  
Vol 44 (3) ◽  
pp. 511-526 ◽  
Author(s):  
Zhang Pingguang ◽  
Cai Suilin

In this paper we study the number and the relative position of the limit cycles of a plane quadratic system with a weak focus. In particular, we prove the limit cycles of such a system can never have (2, 2)-distribution, and that there is at most one limit cycle not surrounding this weak focus under any one of the following conditions:(i) the system has at least 2 saddles in the finite plane,(ii) the system has more than 2 finite singular points and more than 1 singular point at infinity,(iii) the system has exactly 2 finite singular points, more than 1 singular point at infinity, and the weak focus is itself surrounded by at least one limit cycle.


1995 ◽  
Vol 52 (3) ◽  
pp. 461-474 ◽  
Author(s):  
Xianhua Huang ◽  
J.W. Reyn

As a contribution to the solution of Hilbert's 16th problem the question is considered whether in a quadratic system with two nests of limit cycles at least in one nest there exists precisely one limit cycle. An affirmative answer to this question is given for the case that the sum of the multiplicities of the finite critical points in the system is equal to three.


2011 ◽  
Vol 21 (02) ◽  
pp. 425-429 ◽  
Author(s):  
G. A. LEONOV

The existence criterion of three normal size limit cycles in quadratic systems with a weak focus of first order is obtained. Further, giving a finite disturbance for weak focus, the fourth normal size limit cycle is obtained. Bifurcation of appearance of two limit cycles via semistable cycle is given.


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