Forced hyperbolic mean curvature flow

In this paper, we investigate two hyperbolic flows obtained by adding forcing terms in direction of the position vector to the hyperbolic mean curvature flows in \cite{klw,hdl}. For the first hyperbolic flow, as in \cite{klw}, by using support function, we reduce it to a hyperbolic Monge-Amp$\grave{\rm{e}}$re equation successfully, leading to the short-time existence of the flow by the standard theory of hyperbolic partial differential equation. If the initial velocity is non-negative and the coefficient function of the forcing term is non-positive, we also show that there exists a class of initial velocities such that the solution of the flow exists only on a finite time interval $[0,T_{max})$, and the solution converges to a point or shocks and other propagating discontinuities are generated when $t\rightarrow{T_{max}}$. These generalize the corresponding results in \cite{klw}. For the second hyperbolic flow, as in \cite{hdl}, we can prove the system of partial differential equations related to the flow is strictly hyperbolic, which leads to the short-time existence of the smooth solution of the flow, and also the uniqueness. We also derive nonlinear wave equations satisfied by some intrinsic geometric quantities of the evolving hypersurface under this hyperbolic flow. These generalize the corresponding results in \cite{hdl}.Comment: 20 pages. Accepted for publication in Kodai Mathematical Journa

A class of rotationally symmetric quantum layers of dimension 4

Under several geometric conditions imposed below, the existence of the discrete spectrum below the essential spectrum is shown for the Dirichlet Laplacian on the quantum layer built over a spherically symmetric hypersurface with a pole embedded in the Euclidean space R4. At the end of this paper, we also show the advantage and independence of our main result comparing with those existent results for higher dimensional quantum layers or quantum tubes.Comment: 12 pages. A slight different version of this paper has appeared in J. Math. Anal. App

A new way to Dirichlet problems for minimal surface systems in arbitrary dimensions and codimensions

In this paper, by considering a special case of the spacelike mean curvature flow investigated by Li and Salavessa [6], we get a condition for the existence of smooth solutions of the Dirichlet problem for the minimal surface equation in arbitrary codimension. We also show that our condition is sharper than Wang's in [13, Theorem 1.1] provided the hyperbolic angle $\theta$ of the initial spacelike submanifold $M_{0}$ satisfies $\max_{M_{0}}{\rm cosh}\theta>\sqrt{2}$.Comment: 9 pages. Accepted for publication in Kyushu Journal of Mathematic