(ω,c)-asymptotically periodic functions,first-order Cauchy problem,and Lasota-Wazewska model with unbounded oscillating production of red cells

In this paper, we study a new class of functions, which we call (ω,c)-asymptotically periodic functions. This collection includes asymptotically periodic, asymptotically antiperiodic, asymptotically Bloch-periodic, and unbounded functions. We prove that the set conformed by these functions is a Banach space with a suitable norm. Furthermore, we show several properties of this class of functions as the convolution invariance. We present some examples and a composition result. As an application, we prove the existence and uniqueness of (ω,c)-asymptotically periodic mild solutions to the first-order abstract Cauchy problem on the real line. Also, we establish some sufficient conditions for the existence of positive (ω,c)-asymptotically periodic solutions to the Lasota-Wazewska equation with unbounded oscillating production of red cells.     

渐近紧随机动力系统及其极限集的性质

通过对随机动力系统极限行为的研究,推广了传统动力系统的相关定义和理论.由于在无界区域上,Sobolevr紧嵌入的缺乏,Crauel,Debussche及Flancloli等人在研究有界区域上的随机演化系统时所引入的渐近紧的概念不再适用.通过对Ladyzlmnskaya,Rosa等人在对确定性系统的研究中所提出的渐近紧概念的推广,引入了随机动力系统渐近紧的概念,并以相应的示例及严格的理论推导证明了此概念的合理性和必要性.最后,作为这一新的概念的应用,证明了渐近紧随机动力系统极限集的性质.     

A viscosity approach to the Dirichlet problem for complex Monge–Ampère equations

We present a viscosity approach to the Dirichlet problem for the complex Monge–Ampère equation ${\det u_{\bar{j} k} = f (x, u)}$ . Our approach differs from previous viscosity approaches to this equation in several ways: it is based on contact set techniques (the Alexandrov–Bakelman–Pucci estimate), on extensive applications of sup-inf convolutions, and on a relation between real and complex Hessians. More specifically, this paper includes a notion of viscosity solutions; a comparison principle and a solvability theorem; the equivalence between viscosity and pluripotential solutions; an estimate of the modulus of continuity of a solution in terms of that of a given subsolution and of the right-hand side f; and an Alexandrov–Bakelman–Pucci type of L ^∞-estimate.     

Packing spheres and fractal Strichartz estimates in for

We prove an estimate for the spherical average operator in if . This leads to a lower bound for the Hausdorff dimension of unions of certain collections of spheres and to a Strichartz-type estimate for solutions of the wave equation.

     

关于 Fuzzyω正则语言的一个注记

通过引入ω-Nerode等价关系,fuzzy前逆缀ω-语言,闭左逆语言等概念来研究语言的化数性质,得到了(1)fuzzyω正则语言可由一些具有有限指标集的等价类来表示;(2)fuzzy前逆缀ω-语言是fuzzyω正则语言iff由L定义的ω-Nerode等价关系的指标集是有限的.     

Global dynamics of delayed reaction–diffusion equations in unbounded domains

We consider a nonlocal delayed reaction–diffusion equation in an unbounded domain that includes some special cases arising from population dynamics. Due to the non-compactness of the spatial domain, the solution semiflow is not compact. We first show that, with respect to the compact open topology for the natural phase space, the solutions induce a compact and continuous semiflow ${\Phi}$ on a bounded and positively invariant set Y in C ₊?=?C([?1, 0], X ₊) that attracts every solution of the equation, where X ₊ is the set of all bounded and uniformly continuous functions from ${\mathbb{R}}$ to [0, ∞). Then, to overcome the difficulty in describing the global dynamics, we establish a priori estimate for nontrivial solutions after describing the delicate asymptotic properties of the nonlocal delayed effect and the diffusion operator. The estimate enables us to show the permanence of the equation with respect to the compact open topology. With the help of the permanence, we can employ standard dynamical system theoretical arguments to establish the global attractivity of the nontrivial equilibrium. The main results are illustrated with the diffusive Nicholson’s blowfly equation and the diffusive Mackey–Glass equation.     

On a viscous Hamilton-Jacobi equation with an unbounded potential term

We present comparison, uniqueness and existence results for unbounded solutions of a viscous Hamilton-Jacobi or eikonal equation. The equation includes an unbounded potential term V(x) subject to a quadratic upper bound. The results are obtained through a tailor-made change of variables in combination with the Hopf-Cole transformation. An integral representation formula for the solution of the Cauchy problem is derived in the case where V(x)=ω²|x|²/2.     

无界时滞中立型随机微分方程解的矩估计

本文探讨了一类无界时滞的中立型随机微分方程,给出了保证所讨论的方程的整体解存在的条件,并且得到解的某种矩估计.     

Small-divisor equation of higher order with large variable coefficient and application to the coupled KdV equation

In this paper, we establish an estimate for the solutions of small-divisor equation of higher order with large variable coefficient. Then by formulating an infinite-dimensional KAM theorem which allows for multiple normal frequencies and unbounded perturbations, we prove that there are many periodic solutions for the coupled KdV equation subject to small Hamiltonian perturbations.     

Convergence of a misanthrope process to the entropy solution of 1D problems

We prove the convergence, in some strong sense, of a Markov process called “a misanthrope process” to the entropy weak solution of a one-dimensional scalar nonlinear hyperbolic equation. Such a process may be used for the simulation of traffic flows. The convergence proof relies on the uniqueness of entropy Young measure solutions to the nonlinear hyperbolic equation, which holds for both the bounded and the unbounded cases. In the unbounded case, we also prove an error estimate. Finally, numerical results show how this convergence result may be understood in practical cases.     

Coercivity Conditions for Equilibrium Problems

The study of the existence of solutions of equilibrium problems on unbounded domains involves usually the same sufficient assumptions as for bounded domains together with a coercivity condition. We focus on two different conditions: the first is obtained assuming the existence of a bounded set such that no elements outside is a candidate for a solution; the second allows the solution set to be unbounded. Our results exploit the generalized monotonicity properties of the function f defining the equilibrium problem. It turns out that, in both the pseudomonotone and the quasimonotone setting, an equivalence can be stated between the nonemptyness and boundedness of the solution set and these coercivity conditions. In the pseudomonotone case, we compare our coercivity conditions with various coercivity conditions that appeared in the literature.We thank an anonymous referee for valuable comments and suggestions.     

Laplace Equation on a Domain With a Cuspidal Point in Little Hölder Spaces

In this paper, we give new results about existence, uniqueness and regularity properties for solutions of Laplace equation $$\Delta u = h \quad {\rm in} \, \Omega$$ where Ω is a cusp domain. We impose nonhomogeneous Dirichlet conditions on some part of ?Ω. The second member h will be taken in the little Hölder space ${h^{2 \sigma}(\bar{\Omega})}$ with ${\sigma \, \in \, ]0, \, 1/2[}$ . Our approach is based essentially on the study of an abstract elliptic differential equation set in an unbounded domain. We will use the continuous interpolation spaces and the generalized analytic semigroup theory.     

On a resolvent problem for the linearized system from the dynamical system describing the compressible viscous fluid motion

The linearized initial boundary value problem describing the motion of the viscous compressible fluid is studied under Dirichlet zero condition in bounded and unbounded domains. The resolvent estimate for the corresponding operator is proved in the L_p framework and the sharp inner estimate of the resolvent set is obtained. Copyright © 2004 John Wiley Sons, Ltd.     

A singular Monge-Ampère equation on unbounded domains

In this paper, we study the Dirichlet problem for a singular Monge-Amp`ere type equation on unbounded domains. For a few special kinds of unbounded convex domains, we find the explicit formulas of the solutions to the problem. For general unbounded convex domain ?, we prove the existence for solutions to the problem in the space C∞(?) ∩ C(?). We also obtain the local C1/2-estimate up to the ?? and the estimate for the lower bound of the solutions.     

一类非线性非自治可伸缩板方程的一致吸引子

讨论了一类带有初值条件和固定边界条件的非线性非自治可伸缩板方程u_(tt)+△~2u+αu-△u_(tt)-M(||▽u||~2)△u-γ△u_t+f(u)=σ(x,t)证明了该系统的整体适定性.进一步研究了该系统的长时间动力学,利用建立整体弱解所生成的半过程一致渐近紧性,得到了有界区域Ω■R~n(n≥1)或无界开集中一致吸引子的存在性.     

满足递推式紧集的Lipschitz等价性

设紧集U满足一个不交并递推式,U=(rU+(?))∪U_1.证明了若U_1与一个满足强分离条件的自相似集T Lipschitz等价,则U与T也是Lipschitz等价.并举例说明定理在自相似并集间的Lipschitz等价中的应用.     

Upper bounds for the number of solutions of a Diophantine equation

We give upper bound estimates for the number of solutions of a certain diophantine equation. Our results can be applied to obtain new lower bound estimates for the -norm of certain exponential sums.

     

由L\'{e}vy过程驱动的仿射方程关联的无限时区的最优二次控制

讨论线性二次最优控制问题, 其随机系统是由 L\'{e}vy 过程驱动的具有随机系数而且还具有仿射项的线性随机微分方程. 伴随方程具有无界系数, 其可解性不是显然的. 利用 $\mathscr{B}\mathscr{M}\mathscr{O}$ 鞅理论, 证明伴随方程在有限 时区解的存在唯一性. 在稳定性条件下, 无限时区的倒向随机 Riccati 微分方程和伴随倒向随机方程的解的存在性是通过对应有限 时区的方程的解来逼近的. 利用这些解能够合成最优控制.