Uniqueness of positive solutions of a class of quasilinear ordinary differential equations

Abstract. Uniqueness results are obtained for positive solutions of a class of quasilinear ordi-nary differential equations. The methods rely on the energy analysis and a scale argument.     

污染线性模型的非参数估计

Abstract. In this paper, the following contaminated linear model is considered:     

具有四个时滞的平面系统的周期解的存在性

The sufficient condition for the existence of non-constant periodic solutions of the following planar system with four delays are obtained:     

EXISTENCE OF POSITIVE SOLUTIONS AND 1／c-GLOBAL ATTRACTIVITY OF A NONLINEAR DELAY DIFFERENCE EQUATION WITH VARIABLE COEFFICIENTS

Abstract. The existence of positive solutions and the global attractivity of the difference equa-tion     

Estimates of energies and moments for solutions of Boltzmann-Poisson system

In this paper, the properties of the solutions ot Boltzmann-Poisson system in three dimensions are considered. The estimates of the energies (the kinetic and the potential energies) and the γ-th moments with γ∈[2,3) are obtained. The latter answers an open problem.     

关于一类修正的三角插值多项式

本文构造出一个以｛θ_ｋ＝ｋ/(ｎ＋１)π｝^ｎ_ｋ＝１为插值节点的ｆ（θ）∈Ｃ_２π且为奇函数的修正的三角插值多项式Ｗ_n（ｆ;ｒ,θ）（ｒ为自然数）．Ｗ_n（ｆ;ｒ,θ）对每个以２π为周期的奇连续函数都能在全实轴上一致地收敛到ｆ（θ）;若ｆ（θ）∈Ｃ^ｊ_２π（０≤ｊ≤ｒ－１）且是奇的,Ｗ_n（ｆ;ｒ,θ）对其收敛阶均达到最     

Oscillation of a Punch Moving on the Free Surface of an Elastic Half Space

The contact problem concerning oscillation of a circular rigid punch, moving uniformly at sub-Rayleigh speed along the surface of an elastic half space, is investigated using a three-dimensional formulation. Slow motion of the punch is considered, which implies that the characteristic time for the external loading is much larger than the time interval necessary for shear waves to propagate across the punch. An asymptotic solution for the vertical oscillation of the punch is given. It is shown that the vertical displacement of the punch can approximately be described by the equation of dynamics for a system of one degree of freedom with viscous friction. The dependence of the coefficients for effective viscosity and stiffness, occurring in this equation, on the speed of the punch and Poisson ratio of the half space, is investigated. The solution for the non-stationary problem concerning a suddenly applied moving point load is also obtained, correcting and extending the result known so far. Mathematics Subject Classifications (2000) 74H10, 74J05, 74M15.     

Viscous lifting and drainage of a conducting fluid in the presence of a transverse magnetic field

A theoretical investigation of the effects of a transverse magnetic field on the combined problem of viscous lifting and drainage of a conducting fluid on a plate is presented. The effects of inertia and transverse magnetic field on the liquid film thickness is studied for two cases namely a plate withdrawn with a constant velocity and one withdrawn with a constant acceleration. The expressions for the flow rate and the free surface profiles are obtained for the above two cases. It is found that the free surface profiles are convex in nature as in the non-magnetic case thus showing that the inertia does not effect the general pattern of flow, and the effect of the magnetic field is to retard both the lifting and drainage of the fluid.     

On the decay process of turbulence at large Reynolds and Peclet numbers

When fluctuating temperature field is considered to be super imposed on a general field of eddy turbulence, the early period decay phenomena in regard to velocity, temperature and velocity-temperature are guided by three dynamical equations that are obtained here in a straightforward manner. The equations so obtained are simplified for the case of homogeneous turbulence and subsequently for the case of homogeneous and isotropic turbulence.     

一个基于Sidrauski宏观经济动力学模型的分析

Abstract. This paper formulates a kind of dynamical macro-economic model based onSidrauski‘s work,then presents the sufficient and necessary conditions of the stability of modelat equilibrium states ,and shows some results for special production functions.