Sign-changing bubble tower solutions for a Paneitz-type problem

This paper is concerned with the following biharmonic problem <?CDATA ${cases} Δ^2 u = |u|8/N-4u &in \ Ω {{B(ξ_0,ε)}},\\ u = Δ u = 0 &on \ ∂ (Ω {{B(ξ_0,ε)}}), {cases}(0.1) ?> Δ 2 u = | u | 8 N − 4 u in Ω∖ B ( ξ 0 , ε ) ― , u = Δ u = 0 on ∂ ( Ω∖ B ( ξ 0 , ε ) ― ) , where Ω is an open bounded domain in <?CDATAR^N$?> R N , <?CDATA $N{x2A7E} 5$?> N ⩾ 5 , and <?CDATA $B(ξ_0,ε)$?> B ( ξ 0 , ε ) is a ball centered at ξ 0 with radius ɛ , ɛ is a small positive parameter. We obtain the existence of solutions for problem (0.1), which is an arbitrary large number of sign-changing solutions whose profile is a superposition of bubbles with alternate sign which concentrate at the centre of the hole.