A method of determining an amount of nitrogen oxides stored in a NOx trap of an engine exhaust assembly may include determining a mass flow rate of NOx into the NOx trap, determining an efficiency of storing of the NOx within the trap, and calculating the amount of NOx stored in the NOx trap based on the determined mass flow rate and the determined efficiency. A gate electrode is disposed on the active region. The inductive coupler includes a split ferrite core having material selected to provide a substantially flat frequency response between one and 50 megahertz. Therefore, generation of a noise and vibration can be suppressed to save electric power consumption. With this method, sufficient imprint pressure can be used to obtain high quality patterning, a thin and uniform residual layer, and a high fidelity pattern. The process can be performed in a batchwise or continuous mode.