Constant mean curvature hypersurfaces with two principal curvatures in a sphere

In this paper we consider a compact oriented hypersurface M ⁿ with constant mean curvature H and two distinct principal curvatures λ and μ with multiplicities (n − m) and m, respectively, immersed in the unit sphere S ⁿ⁺¹. Denote by the trace free part of the second fundamental form of M ⁿ , and Φ be the square of the length of . We obtain two integral formulas by using Φ and the polynomial . Assume that B _H,m is the square of the positive root of P _H,m (x) = 0. We show that if M ⁿ is a compact oriented hypersurface immersed in the sphere S ⁿ⁺¹ with constant mean curvatures H having two distinct principal curvatures λ and μ then either or . In particular, M ⁿ is the hypersurface .      

对称双弹簧振子受迫、有阻尼横振动的混沌行为

对受周期外力驱动的对称双弹簧振子进行了研究,建立了系统的动力学方程,用线性稳定性分析方法讨论了平衡点附近邻域的稳定性,利用数值计算并结合多种分析方法,求解非线性方程和判断解的性质.通过改变系统参数,画出时域图、相图及分岔图等.计算分析和数值实验发现,这个简单的力学系统存在十分丰富的动力学行为(分岔、混沌).理论分析和数值实验结果一致.     

新三维混沌系统及其电路仿真

提出了一个新的不同于Lorenz系统和Chen系统的三维连续自治混沌系统.该系统含有五个参数,其中两个方程中各含有一个非线性乘积项.通过理论推导、数值仿真、Lyapunov指数谱、分岔图、Lyapunov维数、Poincare截面图研究了系统的基本动力学特性,并分析了改变不同参数时系统动力学行为的变化.最后设计了硬件电路并运用电子工作平台Multisim软件对该电路进行仿真实验,证实了该混沌系统的可实现性. 关键词： 混沌系统 Lyapunov指数 Poincare截面图 电路仿真     

Bifurcations of rough heteroclinic loop with two saddle points

The bifurcation problems of rough 2-point-loop are studied for the case p11 > λ11, p21 < λ21, P11p21 <λ111λ21. where - pi1 < 0 and λi1 > 0 are the pair of principal eigenvalues of unperturbed system at saddle point pi, i = 1,2. Under the transversal and nontwisted conditions, the authors obtain some results of the existence of one 1-periodic orbit, one 1-periodic and one 1-homoclinic loop, two 1-periodic orbits and one 2-fold 1-periodic orbit. Moreover, the bifurcation surfaces and the existence regions are given, and the corresponding bifurcation graph is drawn.     

粘弹性圆薄板的动力学行为

基于线性粘弹性力学中的Boltzmann叠加原理,给出粘弹性圆薄板动力学分析的初边值问题.通过一定的简化后得到描述薄板力学行为的四维非线性非自治动力系统.综合使用非线性动力学中的数值分析方法,研究了参数对粘弹性圆薄板动力学行为的影响.同时计算了吸引子的Lyapunov维、相关维和点形维.     

Poincar and Weak Poincar Inequalities for the Mixed Poisson Measure

By using the Mecke identity, we study a class of birth-death type Dirichlet forms associated with the mixed Poisson measure. Both Poincar and weak Poincar inequalities are established, while another Poincar type inequality is disproved under some reasonable assumptions.     

Generalized integral transform solution for boundary layer flow over a sphere

The generalized integral transform technique is applied to the boundary layer equations for flow over a sphere in their primitive variables. Even though a diffusion-based eigenvalue problem is used, the velocity profile, shear stress and separation point have been calculated with high accuracy. Low-order approximations are shown to be accurate near the surface and the predictions of the separation point is very good. Comparison with finite difference results shows the better convergence behaviour of the integral transform method.     

球面上热核的渐近展开

具体计算了球面Ｓｎ（１）（ｎ２）上热核的渐近展开式中前五项的系数，而根据已有的公式只能算出前四项．最后给出了展开式一般项的递推公式，发现它与Ｂｅｒｎｏｕｌｉ数有未曾想到的联系．根据不变量理论，我们可以确定任意ｎ维紧致无边Ｒｉｅｍａｎｎ流形上热核的渐近展开式中第五项的系数．     

Poincare动力学方程Whittaker降阶法

Ｗｈｉｔｔａｋｅｒ降阶法是利用能量积分将一个完整动力系统的Ｌａｇｒａｎｇｅ运动方程降阶。本文论述了据李群理论构造的Ｐｏｉｎｃａｒｅ方程所描述的非完整保守系统的相应结果。     

某些域上的A_r加权Poincaré型微分形式不等式

证明微分形式的局部加权积分不等式,然后通过利用局部的结果,分别地在 Ls(μ)-平均域和John域上证明了微分形式的整体加权积分不等式,这可以认为是经 典的Poincaré型不等式的推广.