Title: On polar relative normalizations of ruled surfaces,
Abstract: This paper deals with skew ruled surfaces in the Euclidean space
$\mathbb{E}^{3}$ which are equipped with polar normalizations, that is,
relative normalizations such that the relative normal at each point of the
ruled surface lies on the corresponding polar plane. We determine the
invariants of a such normalized ruled surface and we study some properties of
the Tchebychev vector field and the support vector field of a polar
normalization. Furthermore, we study a special polar normalization, the
relative image of which degenerates into a curve.