BIHARMONIC EQUATIONS WITH ASYMPTOTICALLY LINEAR NONLINEARITIES

This article considers the equation △2u = f（x,u）with boundary conditions either u｜aΩ = au/an｜aΩ = 0 or u｜aΩ = △u｜aΩ = 0, where f（x, t） is asymptotically linear with respect to t at infinity, and Ω is a smooth bounded domain in R^N, N 〉 4. By a variant version of Mountain Pass Theorem, it is proved that the above problems have a nontrivial solution under suitable assumptions of f（x, t）.

NONTRIVIAL SOLUTIONS FOR ASYMPTOTICALLY LINEAR HAMILTONIAN SYSTEMS WITH LAGRANGIAN BOUNDARY CONDITIONS

In this article, we study the existence of nontrivial solutions for a class of asymptotically linear Hamiltonian systems with Lagrangian boundary conditions by the Galerkin approximation methods and the L-index theory developed by the first author.

Multiple homoclinics in a non-periodic Hamiltonian system

This paper concerns the existence of multiple homoclinic orbits for the second-order Hamiltonian system-L（t）z＋Wz（t,z）=0,where L∈C（R,RN2）is a symmetric matrix-valued function and W（t,z）∈C1（R×RN,R）is a nonlinear term.Since there are no periodic assumptions on L（t）and W（t,z）in t,one should overcome difficulties for the lack of compactness of the Sobolev embedding.Moreover,the nonlinearity W（t,z）is asymptotically linear in z at infinity and the system is allowed to be resonant,which is a case that has never been considered before.By virtue of some generalized mountain pass theorem,multiple homoclinic orbits are obtained.

ON THE GENERALIZED PLK METHOD AND ITS APPLICATIONS

In this paper,we propose a generalized form of the PLK method.To solve weakly nonlinear prob- lems,in straining the related coordinates ,we choose a kind of transformations including nonlinear functionals of de- pendent variables to linearize asymptotically the original problems,and give more perfect asymptotic solutions with the first-term approximation and the derived transformations.The analysis for some practical examples shows that the generalized method is straightforward and effective and might be applied to more complicated nonlinear problems.

A BIHARMONIC EIGENVALUE PROBLEM AND ITS APPLICATION

In this article, we focus on the eigenvalue problem of the following linear biharmonic equation in R^N：△^2u-αu＋λg（x）u=0 with u ∈H^2（R^N）,u≠0,N≥5Note that there are two parameters α and λ in it, which is different from the usual eigenvalue problems. Here, we consider λ as an eigenvalue and seek Ior a sulble range of parameter α, which ensures that problem （＊） has a maximal eigenvalue. As the loss of strong maximum principle for our problem, we can only get the existence of non-trivial solutions, not positive solutions, in this article. As an application, by using these results, we studied also the existence of non-trivial solutions for an asymptotically linear biharmonic equation in R^N.

Non-Linear Elliptic Equations on Fractal Domain

We consider the following non-linear elliptic equation △u＋ f（x,u）=0,x∈K on fractal domains with zero-Dirichlet boundary conditions, where K is self-similar fractal, △ is the Laplacian defined on K. f（x, t） is asymptotically linear as t→ ∞. We get the non-trivial and non-negative solution by using Mountain Pass lemma.

Stability analysis of extended discrete-time BAMneural networks based on LMI approach

We propose a new approach for analyzing the global asymptotic stability of the extended discrete-time bidirectional associative memory （BAM） neural networks. By using the Euler rule, we discretize the continuous-time BAM neural networks as the extended discrete-time BAM neural networks with non-threshold activation functions. Here we present some conditions under which the neural networks have unique equilibrium points. To judge the global asymptotic stability of the equilibrium points, we introduce a new neural network model - standard neural network model （SNNM）. For the SNNMs, we derive the sufficient conditions for the global asymptotic stability of the equilibrium points, which are formulated as some linear matrix inequalities （LMIs）. We transform the discrete-time BAM into the SNNM and apply the general result about the SNNM to the determination of global asymptotic stability of the discrete-time BAM. The approach proposed extends the known stability results, has lower conservativeness, can be verified easily, and can also be applied to other forms of recurrent neural networks.

ON THE ASYMPTOTIC ASSIGNMENT OF THE BOUNDS OF DECREASING RATE FOR A TIME-VARYING LINEAR CONTROL SYSTEM

In the paper the problem on the assignment of the bounds of decreasing rate for a time-varying linear control system is discussed. The sufficient and necessary condition for bounds of decreasing rate of a time-varying linear system to be assigned arbitrarily is presented. It is pointed out that for any given real number m, M, m<M, there exists a linear state feedback with time-varying gain matrix which makes the corresponding closed-loop system possess M and m as its upper bound and lower bound of the decreasing rate respectively. For the purposes of its application to system design the concept of the asymptotic assignment of the bounds of decreasing rate is also proposed. The method dealing with the asymptotic assignment is given too.

P-symmetric Subharmonic Solutions for Nonlinear Hamiltonian Systems

In this paper,we prove that for each positive k≡1 mod m there exists a P-symmetric kmτ-periodic solution xk for asymptotically linear mτ-periodic Hamiltonian systems,which are nonautonomous and endowed with a P-symmetry.If the P-symmetric Hamiltonian function is semi-positive,one can prove,under a new iteration inequality of the Maslov-type P-index,that xk_(1) and xk_(2) are geometrically distinct for k_(1)/k_(2)≥(2n+1)m+1;and xk_(1),xk_(2) are geometrically distinct for k_(1)/k_(2)≥m+1 provided xk_(1) is non-degenerate.

Central Limit Theorems for Asymptotically Negatively Associated Random Fields

The aim of this paper is to investigate the central limit theorems for asymptotically negatively dependent random fields under lower moment conditions or the Lindeberg condition. Results obtained improve a central limit theorem of Roussas[11]for negatively associated fields and the main results of Su and Chi [18]. and also include a central limit theorem for weakly negatively associated random variables similar to that of Burton et al.[20].

Asymptotically or super linear cooperative elliptic systems in the whole space

Under the assumption that F is asymptotically or super linear as ｜U｜→∞ with U = （u,v）∈R^2, we obtain the existence of ground state solutions of a class of cooperative elliptic systems in NN by using a variant generalized weak linking theorem for strongly indefinite problem developed by Schechter and Zou. To the best of our knowledge, there is no result published concerning the systems in the whole space N^N.

Positive Solutions for Asymptotically Linear Cone-Degenerate Elliptic Equations

In this paper,the authors study the asymptotically linear elliptic equation on manifold with conical singularities-ΔBu+λu=a(z)f(u),u≥0 in R+N,where N=n+1≥3,λ>0,z=(t,x_(1),…,x_(n)),and ΔB=(t■t)^(2)+■^(2)x_(1)+…+■^(2)x_(n).Combining properties of cone-degenerate operator,the Pohozaev manifold and qualitative properties of the ground state solution for the limit equation,we obtain a positive solution under some suitable conditions on a and f.

Asymptotically Isometric Copy of l~β(0<β<1) in Spacesof Bounded Linear Operators

Assume X is a normed space,every x ＊ ∈ S（X＊） can reach its norm at some point in B（X）,and Y is a β-normed space.If there is a quotient space of Y which is asymptotically isometric to l β,then L（X,Y） contains an asymptotically isometric copy of l β.Some sufficient conditions are given under which L（X,Y） fails to have the fixed point property for nonexpansive mappings on closed bounded β-convex subsets of L（X,Y）.

An Application of a Mountain Pass Theorem

We are concerned with the following Dirichlet problem: -△u(x) = f(x, u), x ∈ Ω. u ∈ H_0~1(Ω). (P) where f(x, t) ∈ C(Ω×R), f(x, t)/t is nondecreasing in t ∈ R and tends to an L~∝-function q(x) uniformly in x ∈ Ω as t→+∝ (i.e., f(x, t) is asymptotically linear in t at infinity). In this case. an Ambrosetti-Rabinowitz-type condition, that is. for some θ>2. M>0, 0<θF(x. s)≤ f(x, s)s, for all |s|≥M and x ∈ Ω, (AR) is no longer true, where F(x, s) = integral from n=0 to s f(x, t)dt. As is well known, (AR) is an important technical condition in applying Mountain Pass Theorem. In this paper, without assuming (AR) we prove, by using a variant version of Mountain Pass Theorem, that problem (P) has a positive solution under suitable, conditions on f(x, t) and q(x). Our methods also work for the case where f(x, f) is superlinear in t at infinity. i.e., q(x) ≡∞.

Asymtotics of M-estmation in Non-linear Regression

Consider the standard non-linear regression model y_i=g(x_i,θ_o)+ε_i,i=1,...,n whereg(x,θ)is a continuous function on a bounded closed region X×Θ,θ_o is the unknown parametervector in θ■R_p,{x_1,x_2,...,x_n}is a deterministic design of experiment and{ε_1,ε_2,...,ε_n}is asequence of independent random variables.This paper establishes the existences of M-estimates andthe asymptotic uniform linearity of M-scores in a family of non-linear regression models when theerrors are independent and identically distributed.This result is then used to obtain the asymptoticdistribution of a class of M-estimators for a large class of non-linear regression models.At the sametime,we point out that Theorem 2 of Wang(1995)(J.of Multivariate Analysis,vol.54,pp.227-238,Corrigenda.vol.55,p.350)is not correct.

A Variational ODE and its Application to an Elliptic Problem

In this paper, we consider the following ODE problem { （-u＂（τ）＋（N-1）（N-3）/4τ^2 ）u（τ）＋λu（τ）=f（τ,τ（1-N）/2 u）u（τ）,τ〉0, u∈H, N≥3. （P）,where f ∈ C（（0,＋∞） ×R,R）, f（τ,s） goes to p（τ） and q（τ） uniformly in τ 〉 0 as s→ 0 and s→＋∞ respectively, 0≤ p（τ） ≤ q（τ） ∈L^∞（0,∞）. Moreover, for τ 〉 0, f（τ, s） is nondecreasing in s≥ 0. Some existence and non-existence of positive solutions to problem （P） are proved without assuming that p（τ） = 0 and q（τ） has a limit at infinity. Based on these results, we get the existence of positive solutions for an elliptic problem.