We consider the wave equation in a rectangular domain Cl with homogeneous Dirichlet boundary condition. Let S be an open segment in H, parallel to one of the sides of Ω. We show that if S is shorter than the corresponding side, then for every (arbitrary large) positive number T, there exist smooth initial data such that the corresponding solution of the system is strictly positive in every point of S during the whole time interval (-T, T).
|Original language||English (US)|
|Number of pages||9|
|Journal||Differential and Integral Equations|
|State||Published - Mar 1993|
All Science Journal Classification (ASJC) codes
- Applied Mathematics