A method and apparatus for optimizing multicast traffic in a VLAN-tagged environment is disclosed. The structure includes an upper beam, a transparent drapery blind piece, drapery blind pieces, and counterweight rods. Typically, each helical element executes substantially a full turn around the axis on the outer surface of the core. A method and an apparatus for implementing active control of a wing shape are also described and include the determination of desired lift distribution to determine the improved aerodynamic deflection of the wings. The output pad outputs the digitally processed image data.