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arXiv 2512.04428math.AP
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关于高阶抛物型方程寿命估计的注记

A note on lifespan estimates for higher-order parabolic equations

Nazarbayev University(纳扎尔巴耶夫大学);Institute of Mathematics and Mathematical Modeling(数学与数学建模研究所)

Nurdaulet N. Tobakhanov, Berikbol T. Torebek

AI总结:

研究高阶半线性抛物方程解在初值下的寿命渐近行为,通过测试函数法和半群估计得到上下界,推广并改进了Caristi-Mitidieri和Sun的结果。

摘要:

我们研究了高阶半线性抛物方程 $$u_t+(-\Delta)^m u=|u|^p, \quad x \in \mathbb{R}^n, t>0$$ 在初值条件下解的寿命。我们关注非平凡解寿命的精确渐近行为。通过结合测试函数法和半群估计,我们推导了解寿命的上下界:$$T_{\varepsilon} \simeq \left\{\begin{array}{l}\varepsilon^{-\left(\frac{1}{p-1}-\frac{n}{2m}\right)^{-1}}, \, 1<p<p_{\text {Fuj}}, \\ \exp\left(\varepsilon^{-(p-1)}\right), \, p=p_{\text {Fuj}},\end{array}\right.$$ 其中 $p_{Fuj}=1+\frac{2m}{n}$ 是Fujita临界指数。这些估计改进并推广了Caristi-Mitidieri [J. Math. Anal. Appl., 279:2 (2003), 710-722] 和Sun [Electron. J. Differential Equations, 17 (2010)] 的早期结果,他们仅在慢衰减初值假设下得到了上界。在我们的设定中,上述初值条件被替换为 $L^1\cap L^\infty$ 假设,这强化了前述工作的结果。

英文摘要:

We investigate the lifespan of solutions to the higher-order semilinear parabolic equation $$u_t+(-Δ)^m u=|u|^p, \quad x \in \mathbb{R}^n, t>0 $$ with initial data. We focus on the precise asymptotic behavior of the lifespan of nontrivial solutions. By combining the test function method and semigroup estimates, we derive both upper and lower bounds for the lifespan of solutions $$T_{\varepsilon} \simeq \left\{\begin{array}{l}\varepsilon^{-\left(\frac{1}{p-1}-\frac{n}{2m}\right)^{-1}}, \,\, 1<p<p_{\text {Fuj}}, \\ \exp\left(\varepsilon^{-(p-1)}\right), \,\, p=p_{\text {Fuj}},\end{array}\right.$$ where $p_{Fuj}=1+\frac{2m}{n}$ is the critical exponent of Fujita. These estimates refine and extend the earlier results of Caristi-Mitidieri [J. Math. Anal. Appl., 279:2 (2003), 710-722] and Sun [Electron. J. Differential Equations, 17 (2010)], who obtained only upper bounds under slowly decaying initial data assumptions. In our setting, the above condition on the initial data is replaced by the assumption $L^1\cap L^\infty$, which sharpens the results of the aforementioned works.

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