THE VANISHING PRESSURE LIMIT OF SOLUTIONS TO THE SIMPLIFIED EULER EQUATIONS FOR ISENTROPIC FLUIDS

In this paper,the Riemann problem of the 1-D reduced model for the 2-D Euler equations is considered and the Riemann solutions are obtained.It is proved that,as the pressure vanishes,they converge to two kinds of Riemann solutions to the 1D reduced model for the 2-D transport equations:one contains δ-shocks,the other contains vacuum.     

Spiral solution to the two-dimensional transport equations

The existence of spiral solution for the two-dimensional transport equations is considered in the present paper. Based on the notion of generalized solutions in the sense of Lebesgue-stieltjes integral, the global weak solution of transport equations which includes δ-shocks and vacuum is constructed for some special initial data.     

多变量FUZZY关系方程组解的进一步研究

本文给出一个把多变量ＦＵＺＺＹ关系方程组的求解问题转化为单变量ＦＵＺＺＹ关系方程组来加以解决的方法，这一方法被应用到关于解集结构的研究上，获得了良好的结果。     

一般非线性扩散方程Cauchy问题广义解的渐近性质

本文研究了比较一般的非线性扩散方程的Cauchy问题广义解的渐近性质.利用试验函数与积分估计的方法,获得了广义解当t→∞时的渐近性质以及其广义整体解u(x,t),推广了该类方程Cauchy问题广义解的性质.     

THE RELATION OF TWO-DIMENSIONAL VISCOUS CAMASSA-HOLM EQUATIONS AND THE NAVIER-STOKES EQUATIONS

In this article, the authors show the existence of global solution of two-dimensional viscous Camassa-Holm (Navier-Stokes-alpha) (NS-α) equations. The authors also prove that the solution of the NS-α equations converges to the solution of the 2D NS equations in the inviscid limit and give the convergence rate of the difference of the solution.     

ON THE EXISTENCE AND UNIQUENESS OF THE SOLUTION TO THE NAVIER－STOKES EQUATIONS

ＯＮＴＨＥＥＸＩＳＴＥＮＣＥＡＮＤＵＮＩＱＵＥＮＥＳＳＯＦＴＨＥＳＯＬＵＴＩＯＮＴＯＴＨＥＮＡＶＩＥＲ－ＳＴＯＫＥＳＥＱＵＡＴＩＯＮＳＴａｎｇＸｉａｎｊｉａｎｇ（Ｄｅｐｔ．ｏｆＭａｔｈ．，Ｓｉｃｈｕａｎｕｎｉｖｅｒｓｉｔｙ，Ｃｈｅｎｇｄｕ６１００６４...     

二维土壤溶质输运方程基于POD方法的降阶CN有限体积元外推算法

利用Crank-Nicolson(CN)有限体积元方法和特征投影分解方法建立二维土壤溶质输运方程的一种维数很低、精度足够高的降阶CN有限体积元外推算法,并给出这种外推算法的降阶CN有限体积元解的误差估计和算法的实现.最后用数值例子说明数值结果与理论结果相吻合,并阐明这种降阶CN有限体积元外推算法的优越性.     

THE LARGE TIME GENERIC FORM OF THE SOLUTION TO HAMILTON-JACOBI EQUATIONS

We use Hopf-Lax formula to study local regularity of solution to Hamilton-Jacobi (HJ) equations of multi-dimensional space variables with convex Hamiltonian. Then we give the large time generic form of the solution to We use Hopf-Lax formula to study local regularity of solution to Hamilton-Jacobi (HJ) equations of multi-dimensional space variables with convex Hamiltonian. Then we give the large time generic form of the solution to HJ equation, i.e. for most initial data there exists a constant T > 0, which depends only on the Hamiltonian and initial datum, for t > T the solution of the IVP (1.1) is smooth except for a smooth n-dimensional hypersurface, across which Du(x, t) is discontinuous. And we show that the hypersurface tends asymptotically to a given hypersurface with rate t 1 4 .HJ equation, i.e. for most initial data there exists a constant T > 0, which depends only on the Hamiltonian and initial datum, for t > T the solution of the IVP (1.1) is smooth except for a smooth n-dimensional hypersurface, across which Du(x, t) is discontinuous. And we show that the hypersurface tends asymptotically to a given hypersurface with rate t-1/4 .     

特殊双变量矩阵方程组异类约束解的MCG算法

本文研究了约束矩阵方程问题中异类约束解的迭代算法.利用修正共轭梯度法,求得了特殊双变量线性矩阵方程组的异类约束解,选取特殊的初始矩阵,得到唯一极小范数异类约束解.理论证明和数值算例验证了该方法的有限步收敛性,推广了修正共轭梯度法在求约束矩阵方程问题中的应用范围.     

MATHEMATICAL RESULTS RELATED TO A TWO-DIMENSIONAL MAGNETO- HYDRODYNAMIC EQUATIONS

The two-dimensional magneto-hydrodynamic (MHD) equations are considered in this article. Viscous approximations are used to obtain the local existence and uniqueness of the classical solution. When the viscous term vanishes, the convergence rates, a main problem in turbulence,are also discussed. Moreover, a blow-up criterion for our classical solution is established in terms of the magnetic fields.     

THE RIEMANN PROBLEM WITH DELTA INITIAL DATA FOR THE ONE-DIMENSIONAL CHAPLYGIN GAS EQUATIONS

In this article,we study the Riemann problem with delta initial data for the one-dimensional Chaplygin gas equations.Under the generalized Rankine-Hugoniot conditions and the entropy condition,we const...     

THE GLOBAL L~2 STABILITY OF SOLUTIONS TO THREE DIMENSIONAL MHD EQUATIONS

In this paper,we mainly study the global L2 stability for large solutions to the MHD equations in three-dimensional bounded or unbounded domains.Under suitable conditions of the large solutions,it is shown that the large solutions are stable.And we obtain the equivalent condition of this stability condition.Moreover,the global existence and the stability of two-dimensional MHD equations under three-dimensional perturbations are also established.     

具有非线性梯度项的半线性椭圆型方程的爆炸解

本文在经典摄动方法与椭圆型偏微分方程的估计理论的基础上引入了一种新的方法,对带一般非线性项的二阶椭圆型方程爆炸解的存在性进行了研究,得到了RN(N≥3)上具有C2有界区域Ω上爆炸解的存在性,进而得到全空间RN(N≥3)上爆炸解的存在性.     

一类非线性分数阶泛函微分方程的正解的存在性

本文研究了一类非线性分数阶泛函微分方程.利用锥拉伸与锥压缩不动点定理,得到这类分数阶泛函微分方程的正解的存在性,推广了马如云的结果.     

磁场微极流方程组弱解的正则性准则

本文研究了三维空间中磁场微极流方程组弱解的正则性准则问题.利用能量估计的方法证明了如果速度场以及磁场满足一定的条件,则弱解在(0,T]是唯一的强解.     

REMARKS ON THE LIFESPAN FOR THE SOLUTION TO NONLINEAR WAVE EQUATIONS IN THREE SPACE DIMENSIONS

The authors consider the Cauchy problem for the following nonlinear wave equationswhere x ∈ R3, t ≥ 0, ε > 0 is a small parameter, and obtain the sharp bounds for the lifespan of solution to (0.1). Specially, it is proved that there exist two constants C1 and C2, which are independent of ε, then the lifespan T(ε) satisfies the folowing inequalities     

NONEXISTENCE OF PSEUDO-SELF-SIMILAR SOLUTIONS TO INCOMPRESSIBLE EULER EQUATIONS

In this paper we study a generalization of self-similar solutions. We show that just as for the solutions to the Navier-Stokes equations these supposedly singular solution reduce to the zero solution.In this paper we study a generalization of self-similar solutions. We show that just as for the solutions to the Navier-Stokes equations these supposedly singular solution reduce to the zero solution.     

一般限制线性方程组的迭代解法

本文研究带限制条件的线性方程组Ａｘ＝ｂ，Ｘ∈Ｔ的选代解法，这里Ａ∈Ｃｍ×ｎ，ｂ∈Ｃｍ，Ｔ是Ｃｎ的子空间．我们构造了迭代格式ｘｏ＝０，ｒｋ＝ｂ—Ａｘｋ，ｘｋ＋１＝ｘｋ＋βＹｒｋ，ｋ＝０，１，…其中β是非零实参数，Ｙ是参矩阵；在方程组有解时，给出了参数β与参阵Ｙ的选取方法，以保证选代序列｛ｘｋ｝收敛到它的一个解．     

ON THE SELF-SIMILAR SOLUTIONS OF THE MAGNETO-HYDRO-DYNAMIC EQUATIONS

In this paper, we show that, for the three dimensional incompressible magnetohydro-dynamic equations, there exists only trivial backward self-similar solution in L^p（R^3） for p ≥ 3, under some smallness assumption on either the kinetic energy of the self-similar solution related to the velocity field, or the magnetic field. Second, we construct a class of global unique forward self-similar solutions to the three-dimensional MHD equations with small initial data in some sense, being homogeneous of degree -1 and belonging to some Besov space, or the Lorentz space or pseudo-measure space, as motivated by the work in [5].     

求二维半线性椭圆问题混合元解的二重网格法

1引言求解偏微分方程的混合元方法在实际问题(如油藏和地下水的数值模拟)中有广泛的应用.与标准的有限元相比,混合元方法可以同时求解两个变量即压力和流速的近似,而且能保持问题的局部守恒性,从而得到了更好的结果(如Arnold).现已有许多文献使用混合元法求解线性的(如),拟线性的(如Milner)和非线性的(如Park)二阶椭圆问题.