A new construction of ruled surfaces with constant Disteli-axis in the
dual 3-space D^3
In this study, we construct ruled surfaces whose Disteli-axis is
constant in dual 3-space D^3_1 . Then we attain a general system
characterizing these surfaces, and also give characterizations for a
ruled surface to get a constant Disteli-axis. As a result, the ruled
surface formed by a line undergoing a screw motion is investigated.