The exact internal controllability of the radial solutions of a semilinear heat equation in R3 is proved. The result applies for nonlinearities that are of an order smaller than |s| logp |s| at infinity for 1 ≤ p < 2. The method of the proof combines HUM and a fixed point technique.
We consider the initial-boundary value problem for a nonlinear higher-order nonlinear hyperbolic equation in a bounded domain. The existence of global weak solutions for this problem is established by using the potential well theory combined with Faedo-Galarkin method. We also established the asymptotic behavior of global solutions as by applying the Lyapunov method.
We establish the existence of mild, strong, classical solutions for a class of second order abstract functional differential equations with nonlocal conditions.