Radial basis function approximations to polynomials

A reinforcing sleeve of plastic or a similar material for the ends of hard paper reel cores or the like which form the support cores for wound goods such as paper, foils, textiles or the like. The sleeve comprises a collar adapted to rest against the end faces of the reel core and a radial, hollow projection integrated with the collar and the outer periphery of the sleeve, the projection being adapted to engage one end face of the reel core and to house a driver system. A reinforcing ring is integrated in the collar and comprises a radially extending receiving element for the driver system, the receiving element being integrated in the radial projection and reinforcing it.