Similar Ruled Surfaces with Variable Transformations in the Euclidean   3-space
  In this study, we define a family of ruled surfaces in the Euclidean 3-space E^3 and called similar ruled surfaces. We obtain some properties of these special surfaces and we show that developable ruled surfaces form a family of similar ruled surfaces if and only if the striction curves of the surfaces are similar curves with variable transformation. 
Mehmet \"Onder
math.DG