广义Ginzburg-Landau方程的殆周期解

研究如下广义Ginzburg-Landau方程:μ_t=α₀u+α₁u_xx+α₂|u|²u+α₃|u|²u_x+α₄u²u_x+α₅|u|⁴u+f,证明当函数f(t,x)关于时间t具有殆周期性时,这个方程存在殆周期解     

一类广义Camassa-Holm方程的无限传播速度与渐近行为（英文）

研究了一类广义的Camassa-Holm方程的Cauchy问题.首先,证明当初始值u_0(x)具有紧支集的情况下,方程的解u(x,t)不再具有紧支集.因此,由u_0(x)表示的具有紧支集的初始扰动的传播速度是无限的.其次,当x趋于无穷时,证明了方程的解u(x,t)具有指数衰减.最后,研究了当初始值为指数或代数衰减时,方程的解在无穷远处的渐近行为.     

分支方法在广义MKdV方程中的应用

 应用动力系统分支方法研究广义MKdV方程u_t+bu²u_x-δu_xxx=0的孤立波,且给出了该方程孤立波的显式解及其数目.     

Periodic blow-up solutions and their limit forms for the generalized Camassa–Holm equation

In this paper, we consider the generalized Camassa–Holm equation u_t + 2kux - u_xxt + au²u_x=2u_xu_xx + uu_xxx. Under substitution ξ x = ct, some new explicit periodic wave solutions and their limit forms are presented through some special phase orbits. These periodic wave solutions tend to in?nity on ξ- u plane periodically. Thus we call them periodic blow-up solutions. To our knowledge, such periodic blow-up solutions have not been found in any other equations.     

一类非线性薛定谔方程的孤子解

 研究了具有V(x,t)=f₁(t)x+f₂(t)x²形式的外部势的非线性薛定谔方程的单一孤立子解.结果表明:当孤立子的中心满足带有势V(x,t)的牛顿方程,孤立子的内部结构由"体固定"坐标系决定.孤立子的结构与f₁(t)无关.若f₂(t)与t无关,孤立子是固定的.原则上,若f₂(t)剧烈变化,则孤立子将扩散.但数值计算表明,在一定条件下,孤立子还是经得起f₂(t)的剧烈变化.     

扰动KdV方程解的先验估计

对于带微扰的KdV方程u_t+6uu_x+u_xx=εR(u),(ε＞0),在初值u₀(x)∈C∞(-∞,+∞),当|x|→∞时指数衰减的条件下,分别构造出带两种不同扰动项的KdV方程的扰动孤立波解满足的能量关系式,并运用能量分析方法对扰动的孤立波解进行先验估计,得到如下结论：(1)R(u)=δ(εt)u, δ(s)∈C［0,+∞),δ(0)=0,时,解在-∞＜x＜+∞,0≤εt≤T内一致有界;(2)R(u)=-Δ(εt)u_xxx,Δ(0)=0,Δ(s)∈C¹［0,+∞), 解在-∞＜x＜+∞,0≤εt≤T,0≤ε≤ε₁内一致有界。     

一类Rn上奇异非线性双调和方程正整解的存在性及性质

 以Schauder-Tychonoff不动点定理为工具,建立了一类Rⁿ上奇异非线性双调和方程Δ²_u=f(|x|,u,|▽u|)u^-β(n≥3,β>0)正的径向对称整体解的存在性定理,并给出了解的有关性质.     

一类非线性中立型微分方程的振动定理

 一类非线性混合中立型泛函微分方程(dⁿ/dtⁿ)(x(t)±ax(t-τ)bx(t +τ))(q(t)f(x(t-ρ))+p(t)g(x(t+σ)))=0,被讨论,得到了各种解的振动性的充分条件.     

带有临界指数和奇性的椭圆方程正解的存在性

考虑了一类带权的有狄里克莱边界条件的椭圆方程：－div(|x|^－2au)－λ/|x|^2(a+1)u=|x|^－bpu^p－1+μu^－q,其中0∈ΩR^N(N≥3),0≤a－2/2,a≤b,p=2N/N－2(1+a－b),0<λ<(N－2－2a/2)²,0<q<1. 并利用变分方法,在适当μ的情况下,证明方程至少存在两个正的弱解.     

自相似分形集上双Lipschitz自同构的Lipschitz常数

证明了当自相似集K满足适当条件时， 则一定存在常数c₀>1， 使得对K上的任意一个双Lipschitz自同构映射f， 成立blip（f）=1或者blip（f）≥c₀，这里 lip（g）= supx，y∈K，x≠y |g（x）-g（y）|/|x-y|，blip（g）=max{lip（g），lip（g^-1）}.     

A Linear Hyperbolic System with Stiff Source Terms

We consider the behavior of solutions to the system ut ＋vx =0, vt ＋ux =（au-v）/τ as the relaxation parameter τ approaches 0. If the sub characteristic condition｜a｜ is satisfied, then u approaches a solution to the equilibrium equation ut ＋ aux = 0 and v approaches au. If this condition is violated then solutions have not Fourier transformation when τ→0.     

n阶非线性泛函微分方程正解存在的几个充要条件

利用Ｓｃｈａｕｄｅｒ不动点定理讨论ｎ阶非线性泛函微分方程ｘ￣（ｎ）（ｔ）＋ｐ（ｔ）ｆ（ｘ（ｇ（ｔ）＝ｒ（ｔ）正解全体的构成与正解的存在性．     

Blowup rate of positive solution of a semilinear parabolic system

It is dealt with positive solutions to the systems: u-t-u- XX =v+p, v-t-v XX =u+q in Ω×(0, T) subject to either initial conditions or boundary_value conditions. The exact blowup rate estimates of solution are established under some monotonicity assumptions on the initial values.     

Global and non-global solutions to some chemotaxis model

The paper is concerned with some chemotaxis model ∂u/∂t=D▿(u▿ln(u/w))+u(a−bu),∂w/∂t=f(u,w). To study the behavior of the solution, some function transformations are introduced, and the main tool is sup-sub-solution method. The result shows that, whether the solution blows up in finite time depends on the parameters and the initial data. As the chemical substance w has linear growth, f(u,w)=βu−δw, where β>0, δ>0 and a+δ>0, wherein the solution exists globally. However, as w possesses exponential growth, f(u,w)=(βu−δ)w, wherein both u and w share the same blowup point and time if the solution blows up in finite time. Biography: CHEN Hua(1956–), male, Professor, Ph. D., research direction: partial differential equation and its application.     

具有L1初值的非牛顿多方渗流方程解的正性和熄灭性

利用比较原理和基本解证明了非牛顿多方渗流方程的解在初值u₀(x)∈L¹Ω)及零边值条件下具有正性和熄灭性, 其中m>0, p>1.     

A local asymptotic behavior for ruin probability in the renewal risk model

Let R（t）=u＋ct-∑ I=1^N（t） Xi,t≥0 be the renewal risk model, with Fx（x）being the distribution function of the claim amount X. Let ψ（u） be the ruin probability with initial surplus u. Under the condition of Fx（x） ∈ S^＊（γ）,y ≥ 0, by the geometric sum method, we derive the local asymptotic behavior for ψ（u,u ＋ z] for every 0 （ z （ oo, On one hand, the asymptotic behavior of ψ（u） can be derived from the result obtained. On the other hand, the result of this paper can be applied to the insurance risk management of an insurance company.     

Composition dependence of viscosity for Al（1-x）Mgx（0≤x≤0. 10） alloys

Viscosities of molten Al（1-x）Mgx（0≤x≤0. 10 alloys have been measured in the temperature range of 973 K--1173 K by a torsional oscillation cup method. The viscosity dependence on temperature for Al（1-x）Mgx（0≤x≤0. 10 melts obeys Arrhenius equation. The viscosity increases with increasing magnesium concentration in the investigated system. There is an important relationship between viscosity and its glass-forming ability for metallic melt.     

拟线性分数阶高阶脉冲微分方程边值问题解的存在性

研究了以下一类拟线性分数阶高阶脉冲微分方程边值问题{Dq0+y(t)=A(t,y)y(t)+f(t,y(t),Φy(t),Ψy(t)),■t∈[0,1],q∈(n-1,n],y(i)(0)=0,Δy(i)|t=tk=0,1≤i≤n-2,k=1,2,…,p,Δy|t=tk=Ik(y(t k)),Δy(n-1)|t=tk=Jk(y(tk)),k=1,2,…,p,y(0)=y0+g(y),y(n-1)(1)=y1+∑m-2j=1bjy(n-1)(ξj)解的存在性。通过定义一个压缩映射并利用Banach不动点定理和Krasnoselskii's不动点定理,得到了边值问题存在唯一解和至少存在一个解的充分条件,最后分别给出一个例子来验证主要结果。