The blow-up rate for strongly perturbed semilinear wave equations in the   conformal case
  We consider in this work some class of strongly perturbed for the semilinear wave equation with conformal power nonlinearity. We obtain an optimal estimate for a radial blow-up solution and we have also obtained two less stronger estimates. These results are achieved in three-steps argument by the construction of a Lyapunov functional in similarity variables and the Pohozaev identity. 
M. A. Hamza and O. Saidi
math.AP