A method for estimating the state of a system, as well as an extended Kalman filter, allows nonlinear mathematical models to be used for describing the system. The second film has a thickness smaller than a reference thickness at which the second film would begin to dewet from the substrate if the second film were disposed directly on the substrate. The method then includes receiving first and second clock signals. The valve may be constructed to be either slidable or rotatable between the two positions, and is actuated by a gearing arrangement which is operable at the exterior of the nozzle housing. The delayed AC output current of the plurality of switches may be filtered to provide power to the load.