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arXiv 1806.05906math.AP
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${\mathbb R}^d$中线性heat equation的最优存在类和类非线性动力学

Optimal existence classes and nonlinear--like dynamics in the linear heat equation in ${\mathbb R}^d$

James C. Robinson, Aníbal Rodíguez-Bernal

摘要:

本文用$\int_{{\mathbb R}^d}{\rm e}^{-\varepsilon|x|^2}\,{\rm d}|u_0|<\infty$分析了Radon测度的$M_\varepsilon({\mathbb R}^d)$类中的初始数据的${\mathbb R}^d$中线性热方程解的性质。我们表明,这些类在某种意义上是最佳的局部和全局存在的非负解:特别是$M_0({\mathbb R}^d)=\cap_{\varepsilon>0}M_\varepsilon({\mathbb R}^d)$恰恰是由这些初始数据的热方程的解决方案,可以给所有的时间使用热核表示公式。在考虑这些初始数据的存在性、唯一性和规律性(这些初始数据可以在无穷远处快速增长)之后,我们继续证明它们会产生更多与非线性模型相关的性质。我们证明了有限时间爆破的解决方案,表明爆破点的集合是一个凸集的补充,并给予任何封闭的凸集有一个初始条件,其解决方案保持有界精确在这个集合上的“爆破时间”。我们还表明,野生振荡是可能的,从非负的初始数据作为$t\to\infty$(事实上,我们表明,这种行为是通用的),并且可以规定的行为$u(0,t)$是任何真正的解析函数$γ(t)$上$[0,\infty)$。

英文摘要:

We analyse the behaviour of solutions of the linear heat equation in ${\mathbb R}^d$ for initial data in the classes $M_\varepsilon({\mathbb R}^d)$ of Radon measures with $\int_{{\mathbb R}^d}{\rm e}^{-\varepsilon|x|^2}\,{\rm d}|u_0|<\infty$. We show that these classes are in some sense optimal for local and global existence of non-negative solutions: in particular $M_0({\mathbb R}^d)=\cap_{\varepsilon>0}M_\varepsilon({\mathbb R}^d)$ consists precisely of those initial data for which the a solution of the heat equation can be given for all time using the heat kernel representation formula. After considering properties of existence, uniqueness, and regularity for such initial data, which can grow rapidly at infinity, we go on to show that they give rise to properties associated more often with nonlinear models. We demonstrate the finite-time blowup of solutions, showing that the set of blowup points is the complement of a convex set, and that given any closed convex set there is an initial condition whose solutions remain bounded precisely on this set at the `blowup time'. We also show that wild oscillations are possible from non-negative initial data as $t\to\infty$ (in fact we show that this behaviour is generic), and that one can prescribe the behaviour of $u(0,t)$ to be any real-analytic function $γ(t)$ on $[0,\infty)$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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