R~n和RP~n上的多项式系统

本文讨论了ｎ维欧氏空间Ｒｎ（ｎ＞２）上的多项式向量场集合的系数拓扑不变量，可分为具有不同全局拓扑性质的两类不交的子集合；证明了Ｒｎ上的多项式向量场可连续地延拓成ｎ维射影空间ＲＰｎ上的连续多项式向量场的充要条件，反应了其次数与系数相关的拓扑性质；还证明了平面上的多项式向量场的赤道是闭轨线和不变集的充要条件．     

某些四次多项式微分系统的定性研究

本文研究从化学反应动力学中提出的四次微分系统，得出其有限奇点的全局渐近稳定性和极限环的存在性与不存在性，用ＰＢ规范形方法讨论了Ｈｏｐｆ分叉     

Classification of Teleparallel Homothetic Vector Fields in Cylindrically Symmetric Static Space-Times in Teleparallel Theory of Gravitation

In this paper we classify cylindrically symmetric static space-times according to their teleparallel homothetic vector fields using direct integration technique. It turns out that the dimensions of the teleparallel homothetic vector fields are 4, 5, 7 or 11, which are the same in numbers as in general relativity. In case of 4, 5 or 7 proper teleparallel homothetic vector fields exist for the special choice to the space-times. In the case of 11 teleparallel homothetic vector fields the space-time becomes Minkowski with all the zero torsion components. Teleparallel homothetic vector fields in this case are exactly the same as in general relativity. It is important to note that this classification also covers the plane symmetric static space-times.     

R3中一类二次系统的5个极限环

建立了联系R3中一类二次系统与二维流形球面S2的切向量场之间的桥梁,证明了R3中一类二次系统存在5个极限环,而且这5个极限环分别位于该系统的5个不变闭锥上.     

Vector fields with stable shadowable property on closed surfaces

We prove that the set of vector fields satisfying the C1 stable shadowable property on closed surfaces is characterized as the set of Morse-Smale vector fields. Hence, the vector fields satisfying shadowing property on closed surfaces are C1 dense.     

Bifurcations of limit cycles in a Z 4-equivariant quintic planar vector field

In this paper, a Z4-equivariant quintic planar vector field is studied. The Hopf bifurcation method and polycycle bifurcation method are combined to study the limit cycles bifurcated from the compounded cycle with 4 hyperbolic saddle points. It is found that this special quintic planar polynomial system has at least four large limit cycles which surround all singular points. By applying the double homoclinic loops bifurcation method and Hopf bifurcation method, we conclude that 28 limit cycles with two different configurations exist in this special planar polynomial system. The results acquired in this paper are useful for studying the weakened 16th Hilbert＇s Problem.     

关于Beltrami方程组的很弱解

从考虑向量值函数的每一个分量出发,将Ｂｅｌｔｒａｍｉ方程组转化为一类散度型椭圆组;从而来建立Ｂｅｌｔｒａｍｉ方程组很弱解的正则性：存在可积指数ｒ１和ｒ２,１＜ｒ１＜ｎ＜ｒ２＜∞,使得方程组在低于自然可积指数Ｓｏｂｏｌｅｖ空间Ｗ１,ｒ１ｌｏｃ（Ω,Ｒｎ）中的很弱解,都属于空间Ｗ１,ｒ２ｌｏｃ（Ω,Ｒｎ）,即：ｆ仍是经典意义下的弱解     

具有非退化亦型的Z—阶化李超代数

本文给出了Ｚ－阶化有限维单李超代数具有非退化亦型的一个必要条件。应用这一结果,我们可以得到Ｃａｒｔａｎ型李超代数Ｘ（ｎ）与Ｘ（ｍ,ｎ,ｔ）的Ｋｉｌｌｉｎｇ型是退化的。     

GLOBAL TOPOLOGICAL PROPERTIES OF HOMOGENEOUS VECTOR FIELDS IN R^3

In this paper the authors prove that the flows of homogeneous vector field