一类约束变分问题极小元的存在性及其集中行为

该文主要讨论了一类带有调和位势p-Laplacian方程特征值问题对应的变分泛函极小元的存在性与非存在性,并且使用能量估计的方法分析了当方程中相关参数逼近其临界值时极小元的集中行为.     

与Fisher-Kolmogorov's方程相关的一个差分方程的最快异宿解

该文运用变分法证明了与Fisher-Kolmogorov's方程行波解相关的一个二阶差分方程最快异宿解的存在性.获得了能量泛函在加权Hilbert空间上的最小值点,即最快异宿解.     

一类模拟悬索桥的von Kármán方程的解的存在性

该文研究了一类具有部分自由边界的非线性von Kármán方程,它可以看作是发生大形变悬索桥的数学模型.方程中引入了产生非局部效应的屈曲载荷.通过分析相应能量泛函的临界点,我们得到了方程的解的唯一性和多解性.     

第二类Feigenbaum函数方程凸解的构造

考虑第二类Feigenbaum函数方程{f（x）=1/λf（f（λx））,0〈λ〈1,f（0）=1,0≤f（x）≤1,x∈[0,1]对于给定的初始函数,利用构造性方法讨论上述方程的连续凸解、C^1-凸解和C^2-凸解的存在性及唯一性.     

弱耗散梁方程的渐近性

讨论弱耗散梁方程的能量衰退.通过构造辅助泛函的方法克服了一般的证明能量估计的方法在证明过程中所碰到困难,从而证明了如果记忆核是指数衰退的,那么能量也是指数衰退的.     

一类具有变号位势Kirchhoff型方程解的存在性

该文研究了一类带有变号位势非线性项的Kirchhoff型方程的Neumann边值问题.利用变分方法,首先对空间进行分解,证明了该问题的能量泛函满足山路结构;然后证明了能量泛函的(PS)序列有强收敛的子列;最后通过Ekeland变分原理和山路引理,获得了该问题两个非平凡解的存在性.     

具变指数源项和强阻尼项的波动方程解的渐近稳定性

该文主要讨论下列具强阻尼项的波动方程的初边值问题u_(tt)-div(|▽u|~(p(x)-2)▽u)-△u_t=|u|~(q(x)-2)u解的渐近行为.通过构造一个新的控制函数和利用Sobolev嵌入不等式,建立了源项和能量泛函之间的定性关系.进而,利用Komornik不等式和能量估计,给出了衰减估计.最后,证明u(x,t)=0是渐近稳定的.     

复Clifford分析中的超单演函数

该文研究复Clifford分析中的超单演函数,即方程z_n Df(z)+(n-1)Qf′=0的解. 记f(z)=Pf(z)+Qf(z)e_n,f(z)∈C^2(Ω),f(z): Ω → C^{n+1},Ω C^{n+1}，得出超单演函数的几个性质.     

迁移理论中一类具连续能量的参数方程的解

本文研究迁移理论中含参数δ的具连续能量的板几何中子迁移方程的解.用泛函分析的方法,讨论了使该方程有非零解的参数在复平面上的分布.     

带有积分条件的泛函微分方程的稳定性分析

本文讨论了下列泛函微分方程: 这里T>0,T_1≥0。令Q=bf(a)/c。若Q≤1,则上述方程有唯一平衡点且全局稳定。若Q>1,则上述方程的正平衡点渐近稳定,另一平衡点不稳定。所采用的证明方法是构成Lyapunov泛函和利用广义持征方程,与[2]、[3]不同.当f(y)=y即可得K.L.cooke[3]的结论.当T=T_1=O,f(y)=y即可得[2]的讨论。     

Stability of an $$\varvec{}{}$$th root functional equation in $$\varvec{C}^{*}$$C∗-algebras: a fixed point approach

In this paper, we introduce an \(m{\text{th}}\) root functional equation. Using the fixed point approach, we prove the Hyers–Ulam stability of the \(m{\text{th}}\) root functional equation in \(C^{*}\)-algebras.     

The kernel of the second order Cauchy difference on semigroups

Let S be a semigroup, H a 2-torsion free, abelian group and \(C^2f\) the second order Cauchy difference of a function \(f:S \rightarrow H\). Assuming that H is uniquely 2-divisible or S is generated by its squares we prove that the solutions f of \(C^2f = 0\) are the functions of the form \(f(x) = j(x) + B(x,x)\), where j is a solution of the symmetrized additive Cauchy equation and B is bi-additive. Under certain conditions we prove that the terms j and B are continuous, if f is. We relate the solutions f of \(C^2f = 0\) to Fréchet’s functional equation and to polynomials of degree less than or equal to 2.     

Energy Scaling Law for the Regular Cone

We consider a thin elastic sheet in the shape of a disk whose reference metric is that of a singular cone. That is, the reference metric is flat away from the center and has a defect there. We define a geometrically fully nonlinear free elastic energy and investigate the scaling behavior of this energy as the thickness h tends to 0. We work with two simplifying assumptions: Firstly, we think of the deformed sheet as an immersed 2-dimensional Riemannian manifold in Euclidean 3-space and assume that the exponential map at the origin (the center of the sheet) supplies a coordinate chart for the whole manifold. Secondly, the energy functional penalizes the difference between the induced metric and the reference metric in \(L^\infty \) (instead of, as is usual, in \(L^2\)). Under these assumptions, we show that the elastic energy per unit thickness of the regular cone in the leading order of h is given by \(C^*h^2|\log h|\), where the value of \(C^*\) is given explicitly.     

Flatness implies smoothness for solutions of the porous medium equation

One of the major problems in the theory of the porous medium equation \(\partial _t\rho =\Delta _x\rho ^m,\,m > 1\), is the regularity of the solutions \(\rho (t,x)\ge 0\) and the free boundaries \(\Gamma =\partial \{(t,x): \rho >0\}\). Here we assume flatness of the solution and derive \(C^\infty \) regularity of the interface after a small time, as well as \(C^\infty \) regularity of the solution in the positivity set and up to the free boundary for some time interval. The proof starts from Caffarelli’s blueprint of an improvement of flatness by rescaling, and combines it with the Carleson measure approach applied to the degenerate subelliptic equation satisfied by the pressure of the porous medium equation in transformed coordinates. The improvement of flatness finally hinges on Gaussian estimates for the subelliptic problem. We use these facts to prove the following eventual regularity result: solutions defined in the whole space with compactly supported initial data are smooth after a finite time \(T_r\) that depends on \(\rho _0\). More precisely, we prove that for \(t \ge T_r\) the pressure \(\rho ^{m-1}\) is \(C^\infty \) in the positivity set and up to the free boundary, which is a \(C^\infty \) hypersurface. Moreover, \(T_r\) can be estimated in terms of only the initial mass and the initial support radius. This regularity result eliminates the assumption of non-degeneracy on the initial data that has been carried on for decades in the literature. Let us recall that regularization for small times is false, and that as \(t\rightarrow \infty \) the solution increasingly resembles a Barenblatt function and the support looks like a ball.     

(Bounded) continuous cohomology and Gromov��s proportionality principle

Let X be a topological space, and let C*(X) be the complex of singular cochains on X with coefficients in ${\mathbb{R}}$ . We denote by ${C^{\ast}_{c}(X) \subseteq C^{\ast}(X)}$ the subcomplex given by continuous cochains, i.e. by such cochains whose restriction to the space of simplices (endowed with the compact-open topology) defines a continuous real function. We prove that at least for ??reasonable?? spaces the inclusion ${C^{\ast}_{c}(X) \hookrightarrow C^{\ast}(X)}$ induces an isomorphism in cohomology, thus answering a question posed by Mostow. We also prove that this isomorphism is isometric with respect to the L ^??-norm on cochains defined by Gromov. As an application, we clarify some details of Gromov??s original proof of the proportionality principle for the simplicial volume of Riemannian manifolds, also providing a self-contained exposition of Gromov??s argument.     

Horseshoes for diffeomorphisms preserving hyperbolic measures

We give extensions of Katok’s horseshoe constructions, comment on related results, and provide a self-contained proof. We consider either a \(C^{1+\alpha }\) diffeomorphism preserving a hyperbolic measure or a \(C^1\) diffeomorphism preserving a hyperbolic measure whose support admits a dominated splitting.     

Existence and Stability of Traveling Waves for Degenerate Reaction–Diffusion Equation with Time Delay

This paper deals with the existence and stability of traveling wave solutions for a degenerate reaction–diffusion equation with time delay. The degeneracy of spatial diffusion together with the effect of time delay causes us the essential difficulty for the existence of the traveling waves and their stabilities. In order to treat this case, we first show the existence of smooth- and sharp-type traveling wave solutions in the case of \(c\ge c^*\) for the degenerate reaction–diffusion equation without delay, where \(c^*>0\) is the critical wave speed of smooth traveling waves. Then, as a small perturbation, we obtain the existence of the smooth non-critical traveling waves for the degenerate diffusion equation with small time delay \(\tau >0\). Furthermore, we prove the global existence and uniqueness of \(C^{\alpha ,\beta }\)-solution to the time-delayed degenerate reaction–diffusion equation via compactness analysis. Finally, by the weighted energy method, we prove that the smooth non-critical traveling wave is globally stable in the weighted \(L^1\)-space. The exponential convergence rate is also derived.     

Fixed Points for the Multifractal Spectrum Map

For all continuous function g having a specific form that we call with increasing visibility, we construct a function f whose multifractal spectrum is such that \( d_f =g\circ f\). The function f is obtained as an infinite superposition of piecewise \(C^1\) functions, is also with increasing visibility, and is homogeneously multifractal; i.e., its restriction on any subinterval of \([0,1]\) has the same multifractal spectrum as the function f itself. In particular, we prove the existence of a function f which is its own multifractal spectrum; i.e., \(f=d_f\).     

C1,α Regularity of Viscosity Solutions of Fully Nonlinear Elliptic PDE Under Natural Structure Conditions

In this paper we are concemed with fully nonlinear elliptic equation F(x, u, Du, D²u) = 0. We establish the interior Lipschitz continuity and C^{1,α} regularity of viscosity solutions under natural structure conditions without differentiating the equation as usual, especially we give a new analytic Harnack inequality approach to C^{1,α} estimate for viscosity solutions instead of the geometric approach given by L. Caffarelli \& L. Wang and improve their results. Our structure conditions are rather mild.     

Equivalence of viscosity and weak solutions for the normalized <Emphasis Type="Italic">p</Emphasis>(<Emphasis Type="Italic">x</Emphasis>)-Laplacian

We show that viscosity solutions to the normalized p(x)-Laplace equation coincide with distributional weak solutions to the strong p(x)-Laplace equation when p is Lipschitz and \(\inf p>1\). This yields \(\smash {C^{1,\alpha }}\) regularity for the viscosity solutions of the normalized p(x)-Laplace equation. As an additional application, we prove a Radó-type removability theorem.