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Global existence for reaction-diffusion evolution equations driven by the $ {text{p}} $-Laplacian on manifolds 流形上$ {text{p}} $-拉普拉斯驱动的反应扩散演化方程的整体存在性
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2022-10-28 DOI: 10.3934/mine.2023070
G. Grillo, Giulia Meglioli, F. Punzo
We consider reaction-diffusion equations driven by the $ p $-Laplacian on noncompact, infinite volume manifolds assumed to support the Sobolev inequality and, in some cases, to have $ L^2 $ spectrum bounded away from zero, the main example we have in mind being the hyperbolic space of any dimension. It is shown that, under appropriate conditions on the parameters involved and smallness conditions on the initial data, global in time solutions exist and suitable smoothing effects, namely explicit bounds on the $ L^infty $ norm of solutions at all positive times, in terms of $ L^q $ norms of the data. The geometric setting discussed here requires significant modifications w.r.t. the Euclidean strategies.
我们考虑由$ p $ -拉普拉斯驱动的反应扩散方程,在非紧化的无限体积流形上,假设支持Sobolev不等式,并且在某些情况下,$ L^2 $谱有界于零,我们想到的主要例子是任何维度的双曲空间。结果表明,在所涉及参数的适当条件和初始数据的较小条件下,存在全局的时间解和适当的平滑效果,即在所有正时间解的$ L^infty $范数的显式界,以数据的$ L^q $范数表示。这里讨论的几何设置需要对欧几里得策略进行重大修改。
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引用次数: 0
A symmetry theorem in two-phase heat conductors 两相热导体中的一个对称定理
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2022-10-27 DOI: 10.3934/mine.2023061
Hyeonbae Kang, Shigeru Sakaguchi
We consider the Cauchy problem for the heat diffusion equation in the whole Euclidean space consisting of two media with different constant conductivities, where initially one medium has temperature 0 and the other has temperature 1. Under the assumptions that one medium is bounded and the interface is of class $ C^{2, alpha} $, we show that if the interface is stationary isothermic, then it must be a sphere. The method of moving planes due to Serrin is directly utilized to prove the result.
我们考虑由两个具有不同恒定电导率的介质组成的整个欧几里得空间中的热扩散方程的柯西问题,其中一个介质的初始温度为0,另一个介质温度为1。在假设一个介质是有界的,并且界面是$C^{2,alpha}$类的情况下,我们证明了如果界面是静止等温的,那么它一定是一个球体。直接利用Serrin引起的平面移动方法来证明结果。
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引用次数: 0
Local boundedness for $ p $-Laplacian with degenerate coefficients 退化系数的$p$-Laplacian算子的局部有界性
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2022-09-13 DOI: 10.3934/mine.2023081
P. Bella, Mathias Schaffner
We study local boundedness for subsolutions of nonlinear nonuniformly elliptic equations whose prototype is given by $ nabla cdot (lambda |nabla u|^{p-2}nabla u) = 0 $, where the variable coefficient $ 0leqlambda $ and its inverse $ lambda^{-1} $ are allowed to be unbounded. Assuming certain integrability conditions on $ lambda $ and $ lambda^{-1} $ depending on $ p $ and the dimension, we show local boundedness. Moreover, we provide counterexamples to regularity showing that the integrability conditions are optimal for every $ p > 1 $.
研究了一类原型为$ nabla cdot (lambda |nabla u|^{p-2}nabla u) = 0 $的非线性非一致椭圆型方程的子解的局部有界性,其中变系数$ 0leqlambda $及其逆系数$ lambda^{-1} $允许无界。根据$ p $和维数的不同,在$ lambda $和$ lambda^{-1} $上假设一定的可积条件,给出了局部有界性。此外,我们还提供了正则性的反例,证明了每$ p > 1 $的可积性条件都是最优的。
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引用次数: 0
Potential estimates for fully nonlinear elliptic equations with bounded ingredients 具有有界成分的完全非线性椭圆方程的势估计
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2022-09-05 DOI: 10.3934/mine.2023063
Edgard A. Pimentel, Miguel Walker

We examine $ L^p $-viscosity solutions to fully nonlinear elliptic equations with bounded-measurable ingredients. By considering $ p_0 < p < d $, we focus on gradient-regularity estimates stemming from nonlinear potentials. We find conditions for local Lipschitz-continuity of the solutions and continuity of the gradient. We survey recent breakthroughs in regularity theory arising from (nonlinear) potential estimates. Our findings follow from – and are inspired by – fundamental facts in the theory of $ L^p $-viscosity solutions, and results in the work of Panagiota Daskalopoulos, Tuomo Kuusi and Giuseppe Mingione [10].

我们研究了具有有界可测成分的完全非线性椭圆方程的L^p -粘度解。通过考虑$ p_0 < p < d $,我们关注于非线性势的梯度正则性估计。我们找到了解的局部lipschitz -连续性和梯度的连续性的条件。我们调查了由(非线性)势估计引起的正则性理论的最新突破。我们的发现遵循并受到L^p -粘度解理论中的基本事实的启发,并在Panagiota Daskalopoulos, Tuomo Kuusi和Giuseppe Mingione bbb的工作中得到结果。
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引用次数: 1
Uniqueness of entire solutions to quasilinear equations of $ p $-Laplace type p -拉普拉斯型拟线性方程全解的唯一性
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2022-08-28 DOI: 10.3934/mine.2023068
N. Phuc, I. Verbitsky

We prove the uniqueness property for a class of entire solutions to the equation

where $ sigma $ is a nonnegative locally finite measure in $ mathbb{R}^n $, absolutely continuous with respect to the $ p $-capacity, and $ {rm div}, mathcal{A}(x, nabla u) $ is the $ mathcal{A} $-Laplace operator, under standard growth and monotonicity assumptions of order $ p $ ($ 1 < p < infty $) on $ mathcal{A}(x, xi) $ ($ x, xi in mathbb{R}^n $); the model case $ mathcal{A}(x, xi) = xi | xi |^{p-2} $ corresponds to the $ p $-Laplace operator $ Delta_p $ on $ mathbb{R}^n $. Our main results establish uniqueness of solutions to a similar problem,

in the sub-natural growth case $ 0 < q < p-1 $, where $ mu, sigma $ are nonnegative locally finite measures in $ mathbb{R}^n $, absolutely continuous with respect to the $ p $-capacity, and $ mathcal{A}(x, xi) $ satisfies an additional homogeneity condition, which holds in particular for the $ p $-Laplace operator.

We prove the uniqueness property for a class of entire solutions to the equation begin{document}$ begin{equation*} left{ begin{array}{ll} -{rm div}, mathcal{A}(x,nabla u) = sigma, quad ugeq 0 quad {text{in }} mathbb{R}^n, {liminflimits_{|x|rightarrow infty}}, u = 0, end{array} right. end{equation*} $end{document} where $ sigma $ is a nonnegative locally finite measure in $ mathbb{R}^n $, absolutely continuous with respect to the $ p $-capacity, and $ {rm div}, mathcal{A}(x, nabla u) $ is the $ mathcal{A} $-Laplace operator, under standard growth and monotonicity assumptions of order $ p $ ($ 1 < p < infty $) on $ mathcal{A}(x, xi) $ ($ x, xi in mathbb{R}^n $); the model case $ mathcal{A}(x, xi) = xi | xi |^{p-2} $ corresponds to the $ p $-Laplace operator $ Delta_p $ on $ mathbb{R}^n $. Our main results establish uniqueness of solutions to a similar problem, begin{document}$ begin{equation*} left{ begin{array}{ll} -{rm div}, mathcal{A}(x,nabla u) = sigma u^q +mu, quad ugeq 0 quad {text{in }} mathbb{R}^n, {liminflimits_{|x|rightarrow infty}}, u = 0, end{array} right. end{equation*} $end{document} in the sub-natural growth case $ 0 < q < p-1 $, where $ mu, sigma $ are nonnegative locally finite measures in $ mathbb{R}^n $, absolutely continuous with respect to the $ p $-capacity, and $ mathcal{A}(x, xi) $ satisfies an additional homogeneity condition, which holds in particular for the $ p $-Laplace operator.
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引用次数: 2
Variational analysis in one and two dimensions of a frustrated spin system: chirality and magnetic anisotropy transitions 受抑自旋系统一维和二维的变分分析:手性和磁各向异性跃迁
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2022-07-18 DOI: 10.3934/mine.2023094
Andrea Kubin, Lorenzo Lamberti
We study the energy of a ferromagnetic/antiferromagnetic frustrated spin system where the spin takes values on two disjoint circles of the 2-dimensional unit sphere. This analysis will be carried out first on a one-dimensional lattice and then on a two-dimensional lattice. The energy consists of the sum of a term that depends on nearest and next-to-nearest interactions and a penalizing term related to the spins' magnetic anisotropy transitions. We analyze the asymptotic behaviour of the energy, that is when the system is close to the helimagnet/ferromagnet transition point as the number of particles diverges. In the one-dimensional setting we compute the $ Gamma $-limit of scalings of the energy at first and second order. As a result, it is shown how much energy the system spends for any magnetic anistropy transition and chirality transition. In the two-dimensional setting, by computing the $ Gamma $-limit of a scaling of the energy, we study the geometric rigidity of chirality transitions.
我们研究了铁磁/反铁磁受抑自旋系统的能量,其中自旋在二维单位球的两个不相交的圆上取值。该分析将首先在一维晶格上进行,然后在二维晶格上进行。能量由一个取决于最近和次最近相互作用的项和一个与自旋磁各向异性跃迁有关的惩罚项的总和组成。我们分析了能量的渐近行为,即当粒子数量发散时,系统接近螺旋磁体/铁磁体的过渡点。在一维设置中,我们计算一阶和二阶能量标度的$Gamma$极限。结果表明,系统在任何磁性各向异性跃迁和手性跃迁中花费了多少能量。在二维环境中,通过计算能量标度的$Gamma$极限,我们研究了手性跃迁的几何刚性。
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引用次数: 0
Exact solutions for the insulated and perfect conductivity problems with concentric balls 同心球绝缘和完全导电性问题的精确解
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2022-07-12 DOI: 10.3934/mine.2023060
Zhiwen Zhao
The insulated and perfect conductivity problems arising from high-contrast composite materials are considered in all dimensions. The solution and its gradient, respectively, represent the electric potential and field. The novelty of this paper lies in finding exact solutions for the insulated and perfect conductivity problems with concentric balls. Our results show that there appears no electric field concentration for the insulated conductivity problem, while the electric field for the perfect conductivity problem exhibits sharp singularity with respect to the small distance between interfacial boundaries of the interior and exterior balls. This discrepancy reveals that concentric balls is the optimal structure of insulated composites, but not for superconducting composites.
高对比复合材料的绝缘和完美导电性问题在各个维度上都得到了考虑。溶液及其梯度分别表示电势和场。本文的新颖之处在于找到了同心球的绝缘和完全电导率问题的精确解。结果表明,绝缘电导率问题不存在电场集中,而完美电导率问题的电场在内外球界面边界距离较小的情况下表现出明显的奇异性。这一差异表明同心球是绝缘复合材料的最佳结构,但不适用于超导复合材料。
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引用次数: 1
Bloch estimates in non-doubling generalized Orlicz spaces 非二重广义Orlicz空间中的Bloch估计
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2022-07-01 DOI: 10.3934/mine.2023052
Petteri Harjulehto, P. Hasto, Jonne Juusti

We study minimizers of non-autonomous functionals

when $ varphi $ has generalized Orlicz growth. We consider the case where the upper growth rate of $ varphi $ is unbounded and prove the Harnack inequality for minimizers. Our technique is based on "truncating" the function $ varphi $ to approximate the minimizer and Harnack estimates with uniform constants via a Bloch estimate for the approximating minimizers.

当$varphi$具有广义Orlicz增长时,我们研究了非自治泛函begin{document}$begin{align*}inflimits_uint_Omegavarphi(x,|nabla u|),dxend{align*}$end{document}的极小值。我们考虑$varphi$的上增长率是无界的情况,并证明了极小值的Harnack不等式。我们的技术是基于“截断”函数$varphi$来近似极小值,并通过近似极小值的Bloch估计使用一致常数进行Harnack估计。
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引用次数: 2
Kolmogorov algorithm for isochronous Hamiltonian systems 等时哈密顿系统的Kolmogorov算法
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2022-06-20 DOI: 10.3934/mine.2023035
Rita Mastroianni, C. Efthymiopoulos
We present a Kolmogorov-like algorithm for the computation of a normal form in the neighborhood of an invariant torus in 'isochronous' Hamiltonian systems, i.e., systems with Hamiltonians of the form $ {mathcal{H}} = {mathcal{H}}_0+varepsilon {mathcal{H}}_1 $ where $ {mathcal{H}}_0 $ is the Hamiltonian of $ N $ linear oscillators, and $ {mathcal{H}}_1 $ is expandable as a polynomial series in the oscillators' canonical variables. This method can be regarded as a normal form analogue of a corresponding Lindstedt method for coupled oscillators. We comment on the possible use of the Lindstedt method itself under two distinct schemes, i.e., one producing series analogous to those of the Birkhoff normal form scheme, and another, analogous to the Kolomogorov normal form scheme in which we fix in advance the frequency of the torus.
我们提出了一种类似kolmogorov的算法,用于计算“等时”哈密顿系统中不变环面邻域上的范式,即哈密顿量为$ {mathcal{H}}_0+varepsilon {mathcal{H}}_1 $的系统,其中$ {mathcal{H} _0 $是$ N $线性振子的哈密顿量,并且$ {mathcal{H}}_1 $可展开为振子正则变量中的多项式级数。这种方法可以看作是耦合振荡器相应的Lindstedt方法的正规模拟。我们评论了Lindstedt方法本身在两种不同格式下的可能使用,即,一种产生类似于Birkhoff范式格式的级数,另一种产生类似于Kolomogorov范式格式的级数,其中我们提前固定了环面的频率。
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引用次数: 1
Uniform density estimates and $ Gamma $-convergence for the Alt-Phillips functional of negative powers 负幂的Alt-Phillips泛函的均匀密度估计和$ Gamma $收敛性
IF 1 4区 工程技术 Q2 Mathematics Pub Date : 2022-05-17 DOI: 10.3934/mine.2023086
D. Silva, O. Savin

We obtain density estimates for the free boundaries of minimizers $ u ge 0 $ of the Alt-Phillips functional involving negative power potentials

These estimates remain uniform as the parameter $ gamma to 2 $. As a consequence we establish the uniform convergence of the corresponding free boundaries to a minimal surface as $ gamma to 2 $. The results are based on the $ Gamma $-convergence of these energies (properly rescaled) to the Dirichlet-perimeter functional

considered by Athanasopoulous, Caffarelli, Kenig, and Salsa.

我们得到了涉及负幂势的Alt-Phillips函数的极小子$uge0$的自由边界的密度估计boot{document}$int_Omegaleft(|nabla u|^2+u^{-gamma}chi_{u>0}}right),dx,quadquad gammain(0,2)$end{document}这些估计值与参数$gammato2$保持一致。因此,我们将相应的自由边界到最小曲面的一致收敛性建立为$gamma~2$。结果基于这些能量的$Gamma$收敛性(适当地重新缩放)到Athanasopoulous、Caffarelli、Kenig和Salsa认为的Dirichlet周长泛函beart{document}$int_{Omega}|nabla u|^2 dx+Per_{ Omega}。
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引用次数: 2
期刊
Mathematics in Engineering
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