The sharp estimates of eigenvalues of Polyharmonic operator and higher   order Stokes operator
  In this paper, we establish some lower bounds for the sums of eigenvalues of the polyharmonic operator and higher order Stokes operator, which are sharper than the recent results in \cite{CSWZ13, I13}. At the same time, we obtain some certain bounds for the sums of positive and negative powers of eigenvalues of the polyharmonic operator. 
Daguang Chen and He-Jun Sun
math-ph math.MP math.SP