Thin flexible piezoelectric transducers are bonded to or imbedded into oilfield tubular members or structural members. A reflector spacing gap or cavity between the radiating component and the reflector has a height which is less than a predetermined height of a free-space reflector spacing cavity associated with desired gains for frequencies of interest. A swivel arm that can be swiveled around the swiveling axis and that carries the absorber element. A conveyor introduces a core into the channel. Each band is rendered and transferred to the printer engine until the whole image is printed. A second bias current source connects to a second resistive circuit and a second subcircuit portion.