具阻尼项的Klein—Gordon方程组整体解的存在性、衰减性和爆破性

本文研究如下具阻尼项的Klein-Gordon方程组uu Ut-Δu u-|v|^ρ＋2|u|^ρu=0 vu vt-Δv v-|u|^ρ 2|v|c^ρv=0的初边值问题，得到了整体局解的存在唯一性和指数衰减性，给出了当初始能量为正但具有确定上界时及初始能量为负时解的爆破性。     

Some solutions of the linear and nonlinear Klein-Gordon equations using the optimal homotopy asymptotic method

We investigate the effectiveness of the Optimal Homotopy Asymptotic Method (OHAM) in solving time dependent partial differential equations. To this effect we consider the homogeneous, non-homogeneous, linear and nonlinear Klein-Gordon equations with boundary conditions. The results reveal that the method is explicit, effective, and easy to use.     

Wave operators to a quadratic nonlinear Klein-Gordon equation in two space dimensions

We study asymptotics around the final states of solutions to the nonlinear Klein-Gordon equations with quadratic nonlinearities in two space dimensions , where . We prove that if the final states

     

非线性Klein-Gordon方程柯西问题解的整体存在性与Blow-up

研究非线性Klein-Gordon方程的柯西问题u_(tt)-Δu+u=u|u|~(p-1),x∈R~n,t>0;u(x,0)=u_0(x),u_t(x,0)=u_1(x),x∈R~n.通过引进一族位势井,得到了解的整体存在性与不存在的门槛结果.     

一类耦合非线性Klein-Gordon方程组解的稳定集和不稳定集

利用势井理论的构造方程un-△u u-|v|^ρ 2|u|^ρ△ρu=0;vu-△v v-|u|^ρ＋2|v|^ρv=0的初边值问题的稳定集和不稳定集。证明了当初值属于稳定集时，整体弱解存在，当初值在不稳定集时，解将爆破。     

Long time decay for 2D Klein-Gordon equation

We obtain a dispersive long-time decay in weighted energy norms for solutions of the 2D Klein-Gordon equations. The decay extends the results obtained by Jensen, Kato and Murata for the equations of Schrödinger's type by the spectral approach. For the proof we modify the approach to make it applicable to relativistic equations.     

Stability of the standing waves for a class of coupled nonlinear Klein-Gordon equations

This paper deals with the standing waves for a class of coupled nonlinear Klein-Gordon equations with space dimension N ≥ 3, 0 〈 p, q 〈 2/N-2 and p ＋ q 〈 4/N. By using the variational calculus and scaling argument, we establish the existence of standing waves with ground state, discuss the behavior of standing waves as a function of the frequency ω and give the sufficient conditions of the stability of the standing waves with the least energy for the equations under study.     

Asymptotic Decomposition for Nonlinear Damped Klein-Gordon Equations

In this paper, we prove that if the solution to the damped focusing Klein-Gordon equations is global forward in time with bounded trajectory, then it will decouple into the superposition of divergent equilibriums. The core ingredient of our proof is the existence of the "concentration-compact attractor” introduced by Tao which yields a finite number of asymptotic profiles. Using the damping effect, we can prove all the profiles are equilibrium points.     

Instability of the standing waves for nonlinear Klein-Gordon equations with damping term

This paper is concerned with the nonlinear Klein-Gordon equations with damping term. In terms of the variational argument, the sharp conditions for blowing up and global existence are derived out by applying the potential well argument and using the concavity method. Further, the instability of the standing waves is shown.     

On global small amplitude solutions to systems of cubic nonlinear Klein-Gordon equations with different mass terms in one space dimension

We consider the Cauchy problem for systems of cubic nonlinear Klein-Gordon equations with different mass terms in one space dimension. We prove some result concerning the global existence of small amplitude solutions and their asymptotic behavior. As a consequence, we see that the condition for small data global existence is actually influenced by the difference of masses in some cases.     

Scattering operator for nonlinear Klein-Gordon equations in higher space dimensions

We prove the existence of the scattering operator in the neighborhood of the origin in the weighted Sobolev space Hβ,1 with for the nonlinear Klein-Gordon equation with a power nonlinearity

     

ORBITAL INSTABILITY OF STANDING WAVES FOR THE COUPLED NONLINEAR KLEIN-GORDON EQUATIONS

This paper deals with a type of standing waves for the coupled nonlinear Klein-Gordon equations in three space dimensions. First we construct a suitable constrained variational problem and obtain the existence of the standing waves with ground state by using variational argument. Then we prove the orbital instability of the standing waves by defining invariant sets and applying some priori estimates.     

EXISTENCE TIME FOR SOLUTIONS OFSEMILINEAR DIFFERENT SPEED KLEIN-GORDONSYSTEM WITH WEAK DECAY DATA IN 1D

0 IntroductionWe know tliat tliere are a lot Of results on the lower bouud problem for the life-span ofsolutions to the following senillinear Klein-Gordoli equationDu + u = F(u, 0tu, 0xu), x E IRa,ult=0 = Ere, (0.0.1)0tuIt=o = eu1with sluall, smootli Cauchy data.For tl1e weak decay Caucl1y data, Delort studied tl1at question witl1 periodic Cauchy data inI41. He got a lOwer bound fOr tlie tinle of eristellce. of maghtude cE--2 f fOr a general nonlinearityalld there are exau1ples showili…     

On dispersive properties of discrete 2D Schrödinger and Klein-Gordon equations

We derive the long-time asymptotics for solutions of the discrete 2D Schrödinger and Klein-Gordon equations.     

具有弱衰减初值的不同速度的半线性Klein-Gordon方程组解的生命区间估计

本文讨论了具弱衰减Cauchy初值的不同速度半线性Klein-Gordon方程组解的生命区间估计问题.当初值具有尺度ε时,得到生命区间的下界估计ε-2|logε|-α。（当空间维数d≥3时。α=2,当d=2时α=3）.     

On the existence of signed and sign-changing solutions for a class of superlinear Schrödinger equations

This paper deals with a semilinear Schrödinger equation whose nonlinear term involves a positive parameter λ and a real function f(u) which satisfies a superlinear growth condition just in a neighborhood of zero. By proving an a priori estimate (for a suitable class of solutions) we are able to avoid further restrictions on the behavior of f(u) at infinity in order to prove, for λ sufficiently large, the existence of one-sign and sign-changing solutions. Minimax methods are employed to establish this result.     

THE FINITE DIFFERENCE METHOD FOR DISSIPATIVE KLEIN-GORDON-SCHRODINGER EQUATIONS IN THREE SPACE DIMENSIONS

A fully discrete finite difference scheme for dissipative Klein-Gordon-SchrSdinger equations in three space dimensions is analyzed. On the basis of a series of the time-uniform priori estimates of the difference solutions and discrete version of Sobolev embedding the- orems, the stability of the difference scheme and the error bounds of optimal order for the difference solutions are obtained in H2 × H2 ×H1 over a finite time interval. Moreover, the existence of a maximal attractor is proved for a discrete dynamical system associated with the fully discrete finite difference scheme.     

Global Exact Boundary Controllability for Cubic Semi-linear Wave Equations and Klein-Gordon Equations

The authors prove the global exact boundary controllability for the cubic semi-linear wave equation in three space dimensions, subject to Dirichlet, Neumann, or any other kind of boundary controls which result in the well-posedness of the corresponding initial-boundary value problem. The exponential decay of energy is first established for the cubic semi-linear wave equation with some boundary condition by the multiplier method, which reduces the global exact boundary controllability problem to a local one. The proof is carried out in line with [2, 15]. Then a constructive method that has been developed in [13] is used to study the local problem. Especially when the region is star-complemented, it is obtained that the control function only need to be applied on a relatively open subset of the boundary. For the cubic Klein-Gordon equation, similar results of the global exact boundary controllability are proved by such an idea.     

Global solutions for nonlinear Klein-Gordon equations in infinite homogeneous waveguides

In this paper we prove a global existence result for nonlinear Klein-Gordon equations in infinite homogeneous waveguides, R×M, with smooth small data, where M=(M,g) is a Zoll manifold, or a compact revolution hypersurface. The method is based on normal forms, eigenfunction expansion and the special distribution of eigenvalues of the Laplace-Beltrami on such manifolds.     

一类耦合非线性Klein-Gordon方程组的驻波

该文在二维空间中研究了一类耦合非线性Klein-Gordon方程组的初值问题.首先用变分法证明了具基态的驻波的存在性;其次根据这个结果证明了该初值问题解爆破和整体存在的最佳条件;最后证明了具基态的驻波的不稳定性.