The topological sensitivity analysis method has been recognized as a promising, fast, and accurate approach for solving topology optimization and inverse problems. It is based on developing an asymptotic expansion of a design functional with respect to the creation of a small hole inside the computational domain. In this work, we extend this method to the narrow escape problem. The biological process is governed by a parabolic diffusion equation. We derive a sensitivity analysis for the parabolic problem solution with respect to the creation of a small absorbing boundary subset. We develop a rigorous mathematical framework that is valid in two- and three-dimensional space. It provides an asymptotic formula that describes the behavior of the perturbed solution with respect to the location and size of an arbitrary perturbed boundary subset. The Sobolev capacity notion has been employed to measure the smallness of the boundary subset and to describe the asymptotic behavior with respect to the perturbation size. The performed mathematical analysis is general and can be adapted for a large class of partial differential equations. The obtained asymptotic formula can serve as a useful tool to perform numerical algorithms for solving optimization and control problems.
In this paper, we study the existence of the solutions for the following \(p\)-Kirchhoff equation on bounded domain \[\begin{cases}-\Bigg(a+b\displaystyle\int_{\Omega}|\nabla u|^pdx\Bigg)\Delta_pu+\lambda|u|^{p-2}u=h(u), &x \in \Omega,\\ u=0, &x\in\partial\Omega,\end{cases}\] with prescribed mass \[\int_{\Omega}|u|^pdx=m^p,\] where \(2\leq p\lt 3\), \(a\gt 0\), \(b\gt 0\) are positive constants, \(h(u)\) is a general nonlinearity with Sobolev subcritical growth, \(\Delta_p u=\operatorname{div}(|\nabla u|^{p-2}\nabla u)\) is the \(p\)-Laplacian operator, \(\Omega\subset\mathbb{R}^3\) is a bounded domain, \(\lambda\in \mathbb{R}\) appears as a Lagrange multiplier. First, we prove that the equation admits a positive solution which is a local minimizer when \(h\) is \(L^p\)-subcritical or \(L^p\)-critical at infinity by Brezis-Nirenberg technique. Moreover, we get the multiplicity result by using the genus theory. Next, we prove that the equation has a local minimizer when \(h\) is \(L^p\)-supercritical. Besides, by using the Pohozaev analysis, we prove that in this case, if \(\Omega\) is a star-shaped domain with respect to the origin, the equation admits a second solution which is mountain pass type. To the best of our knowledge, this work seems to be the first contribution on the existence of normalized solutions for \(p\)-Kirchhoff equation on bounded domain.
This paper investigates the oscillatory behavior of solutions to a class of second-order nonlinear neutral delay differential equations with both positive and negative terms of the form \[\left(a(\theta) z^{\prime}(\theta)\right)^{\prime} - p(\theta)x(\theta) + q(\theta)x^{\alpha}(\sigma(\theta)) = 0, \quad \theta \geq \theta_{0},\] where \(z(\theta) = x(\theta) + b(\theta)x(\tau(\theta))\). To facilitate the analysis, the equation is transformed, via a positive solution of an auxiliary second-order ordinary differential equation, into a binomial form. By employing the comparison and integral averaging techniques together with the arithmetic-geometric mean inequality, we establish new sufficient conditions for the oscillation of all solutions. The results obtained extend and improve several existing criteria in the literature. Finally, illustrative examples are presented to demonstrate the effectiveness, novelty, and applicability of the proposed oscillation criteria.
This paper investigates a class of strongly indefinite Choquard equations formulated on the two-dimensional unit ball \(B\). Specifically, consider the following equation: \[\begin{cases}-\Delta u+V(x)u=(I_{\mu}\ast F(u))f(u), &x\in B, \\ u\in H^1_{0,\mathrm{rad}}(B), & \end{cases}\] where \(\mu\in(0,2)\) and \(I_{\mu}\) represents the classical Riesz potential. A fundamental hypothesis is that zero lies within a spectral gap of the Schrödinger operator \(-\Delta+V\). Furthermore, the continuous nonlinearity \(f(t)\) is characterized by a supercritical exponential growth governed by \(\exp[(\beta+|x|^{\alpha})t^{2}]\) with \(\beta, \alpha\gt 0\). Most existing works on this problem are limited to the subcritical or critical exponential growth cases. However, dealing with supercritical growth is much more difficult, especially when estimating the exact upper bound of the minimax levels. To overcome this, we use an approximation method and fine estimates to prove that this indefinite problem has a positive ground state solution. Our approach can also be applied to other elliptic problems with supercritical growth.
We explicate the difference between the function theory of one complex variable and the function theory of several complex variables. In particular, we use the inhomogeneous Cauchy-Riemann equations to explain why there is a Hartogs extension phenomenon in several complex variables but not in one complex variable.
