In a method and apparatus for making welded large pipes, a leading end of a hot strip is connected to a trailing end of a leader strip and then subjected to a two-stage leveling for strip flatness in transverse direction and strip flatness in longitudinal direction. The preform has an extension beyond a footprint of the die. The measurement probe may comprise, for example, an arm cuff through which the device monitors the blood pressure of the subject. The classification data may be used to select and generate the graphical objects. Top support formations lie in a top planar surface of the mat. In particular, the present invention provides an electrostatic valve for flow manipulation in a microfluidic device.