Apparatus and methods for fitting mechanical parts to minimize prevent free play are described. A flat plate antenna for ground waves is fixed on a printed board, and a two-point feeding type patch antenna is placed and fixed on a metallic flat plate of the plate antenna. The light emitted by the laser diode is irradiated onto an optical disc. The method can be used advantageously in controllers having non-volatile memories. Methods, systems and apparatus rely upon a reverse loop for reversing the flow of medium within an adsorption material, allowing particulates caught within the adsorption material to be preferentially moved through and out of the adsorption material.