各向异性次Laplace算子和拟p-次Laplace算子的Picone恒等式及其应用

本文首次把欧氏空间中的各向异性Laplace算子和拟p-Laplace算子分别引入到Heisenberg群Hn上,分别称为各向异性次Laplace算子和拟p-次Laplace算子,不仅建立它们相对应的Picone恒等式,而且还给出这些Picone恒等式的应用,从而把欧氏空间中的相关结果推广到Heisenberg群H~n上.     

Heisenberg群上半线性方程解的非存在性定理

本文利用Rellich恒等式建立了Heisenberg群上一类半线性方程解的非存在性结果．     

Carnot群上一类半线性方程的Liouville型定理

本文研究了Carnot群上一类具有超线性非齐次项的半线性次Laplace方程非负解的存在性问题.结合Birindelli等[4]在Heisenberg群上利用积分不等式研究解的方法和拟齐性分析技巧,给出了此类方程在Carnot群上的一类Liouville型定理.     

Heisenberg群上的Hardy不等式与Pohozaev恒等式

本文对Heisenberg群Hn上的p次Laplace算子ΔHn,p构造了基本解,建立了关于基向量场的Picone恒等式,进而建立了Hardy不等式.利用向量场的非交换运算导出了Pohozaev恒等式.这些结果均推广了Folland,Garofalo-Lanconelli已有的结果,而方法则有所改进.最后给出了在非线性次椭圆方程中的应用.     

Heisenberg型群上的不存在性定理

本文建立了Heisenberg型群G上的一些积分恒等式 ,得到了G上半线性次Laplace方程非负解的一个不存在性定理     

关于齐次Carnot群上广义Morrey空间中一些性质（英文）

本文研究了关于Heisenberg群上的广义Morrey空间和Carnot群上的Lebesgue空间中Riesz位势算子或者分数阶极大算子的行为.根据Heisenberg群中抽象调和分析方法以及sub Laplacian算子的Dirichlet问题解的表示公式,本文主要给出了关于齐次Carnot群G上消失的广义Morrey空间V L~(p,?)(G)中的加权Hardy算子、分数阶极大算子和分数阶位势算子的有界性刻画.进而也得到无消失模的广义Morrey空间上Morrey位势的浸入不等式.所有这些结果推广了关于Heisenberg群上的广义Morrey空间和Carnot群上的Lebesgue空间中的相关结论.     

各向异性Laplace算子的一个非线性Picone恒等式及其应用（英文）

本文针对各向异性Laplace算子,建立了一个非线性Picone恒等式.作为它的应用,得到了各向异性椭圆方程的Sturmian比较原理、各向异性椭圆系统的Liouville定理和广义的各向异性Hardy型不等式.     

一个新的非线性Picone恒等式及其应用（英文）

本文建立一个新的非线性Picone恒等式,它包括一些已有的Picone恒等式.利用这个新的Picone恒等式,我们给出了带奇异项p-Laplace方程的Sturm比较原理,p-Laplace方程组的Liouville定理和带权Hardy不等式.由这里一般的带权Hardy型不等式,我们可以得到几个新的有趣的带权型Hardy不等式.     

各向异性Heisenberg群上带余项的Hardy型不等式

利用一些非常精细的估计技巧,证明了各向异性Heisenberg群上的一类带余项的Hardy型不等式,推广了最近文献中关于Heisenberg群上的带余项的Hardy型不等式的结果.     

Heisenberg群上低阶项可控型非齐次左不变LPDO的局部可解性

本文通过引进可控型左不变算子的概念,讨论了Heisenberg群上非齐次左不变LPDO的局部可解性,得到了一些关于这类算子局部可解的充要条件。     

Almost automorphic and pseudo-almost automorphic mild solutions to an abstract differential equation in Banach spaces

In this paper we prove some existence results for almost automorphic and pseudo-almost automorphic mild solutions to a class of abstract differential equations in Banach spaces. The main technique is based on some composition theorems combined with the contraction mapping theorem. Finally, we present an application to a semilinear partial differential equation with Dirichlet conditions.     

Mean Value Theorem and Pohozaev Type Identities of Generalized Greiner Operator and Their Applications

In this paper, a fundamental solution at the origin and mean value theorem of generalized Greiner operator are given. Then the Hardy type inequality and some Pohozaev type identities are proved. As their applications, some nonexistence results of semilinear nonelliptic equation and unique continuation are discussed.     

Existence and comparison theorems for partial differential equations of Riccati type

In this paper, we discuss the partial differential equation of Riccati type that describes the optimal filtering error covariance function for a linear distributed-parameter system with pointwise observations. Since this equation contains the Dirac delta function, it is impossible to apply directly the usual methods of functional analysis to prove existence and uniqueness of a bounded solution. By using properties of the fundamental solution and the classical technique of successive approximation, we prove the existence and uniqueness theorem. We then prove the comparison theorem for partial differential equations of Riccati type. Finally, we consider some applications of these theorems to the distributed-parameter optimal sensor location problem.     

Picard-Vessiot theory for real fields

The existence of a Picard-Vessiot extension for a homogeneous linear differential equation has been established when the differential field over which the equation is defined has an algebraically closed field of constants. In this paper, we prove the existence of a Picard-Vessiot extension for a homogeneous linear differential equation defined over a real differential field K with real closed field of constants. We give an adequate definition of the differential Galois group of a Picard-Vessiot extension of a real differential field with real closed field of constants and we prove a Galois correspondence theorem for such a Picard-Vessiot extension.     

Three solutions for a Dirichlet problem with one-sided growth conditions on the nonlinearities

We consider a semilinear elliptic partial differential equation, depending on two positive parameters $\lambda$ and $\mu$, coupled with homogeneous Dirichlet boundary conditions. Assuming only one-sided growth conditions on the nonlinearities involved, we prove the existence of at least three weak solutions for $\lambda$ and $\mu$ lying in convenient intervals. We employ techniques of nonsmooth analysis introduced by Degiovanni and Zani, and a theorem of Ricceri for multiplicity of local minimizers.     

On the asymptotic positivity of solutions for the extended Fisher–Kolmogorov equation with nonlinear diffusion

The objective of this paper aims to prove positivity of solutions for a semilinear dissipative partial differential equation with non‐linear diffusion. The equation is a generalized model of the well‐known Fisher–Kolmogorov equation and represents a class of dissipative partial differential equations containing differential operators of higher order than the Laplacian. It arises in a variety of meaningful physical situations including gas flows, diffusion of an electron–ion plasma and the dynamics of biological populations whose mobility is density dependent. In all these situations, the solutions of the equation must be positive functions. Copyright © 2002 John Wiley & Sons, Ltd.     

OSCILLATION FOR NONLINEAR SECOND-ORDER DYNAMIC EQUATIONS ON TIME SCALES

Through the use of generalized Riccati transformation techniques, we establish some oscillation criteria for one type of nonlinear dynamic equation on time scales. Several examples, including a semilinear dynamic equation and a nonlinear Emden-Fowler dynamic equation, are also given to illustrate these criteria and to improve the results obtained in some references.     

Existence results of semilinear differential variational inequalities without compactness

ABSTRACT

The purpose of this paper is to study a class of semilinear differential variational systems with nonlocal boundary conditions, which are obtained by mixing semilinear evolution equations and generalized variational inequalities. First we prove essential properties of the solution set for generalized variational inequalities. Then without requiring any compactness condition for the evolution operator or for the nonlinear term, two existence results for mild solutions are established by applying a weak topology technique combined with a fixed point theorem.     

Generalized Directional Gradients, Backward Stochastic Differential Equations and Mild Solutions of Semilinear Parabolic Equations

We study a forward-backward system of stochastic differential equations in an infinite-dimensional framework and its relationships with a semilinear parabolic differential equation on a Hilbert space, in the spirit of the approach of Pardoux-Peng. We prove that the stochastic system allows us to construct a unique solution of the parabolic equation in a suitable class of locally Lipschitz real functions. The parabolic equation is understood in a mild sense which requires the notion of a generalized directional gradient, that we introduce by a probabilistic approach and prove to exist for locally Lipschitz functions. The use of the generalized directional gradient allows us to cover various applications to option pricing problems and to optimal stochastic control problems (including control of delay equations and reaction--diffusion equations), where the lack of differentiability of the coefficients precludes differentiability of solutions to the associated parabolic equations of Black--Scholes or Hamilton-Jacobi-Bellman type.     

Comparison Method of Stability Analysis of Semilinear Time-Delay Stochastic Evolution Equation

Abstract

In this paper, we set up the comparison theorem between the mild solution of semilinear time-delay stochastic evolution equation with general time-delay variable and the solution of a class (1-dimension) deterministic functional differential equation, by using the Razumikhin–Lyapunov type functional and the theory of functional differential inequalities. By applying this comparison theorem, we give various types of the stability comparison criteria for the semilinear time-delay stochastic evolution equations. With the aid of these comparison criteria, one can reduce the stability analysis of semilinear time-delay stochastic evolution equations in Hilbert space to that of a class (1-dimension) deterministic functional differential equations. Furthermore, these comparison criteria in special case have been applied to derive sufficient conditions for various stability of the mild solution of semilinear time-delay stochastic evolution equations. Finally, the theories are illustrated with some examples.