This invention refers to an ion mobility spectrometer in a fluid subjected to an electric field and an acoustic wave for the selective detection, classification and quantitative determination of the concentration of charged particles, based on their electrical mobility. The fuel metering unit is disposed in the high-pressure pump, and the outlet of the regulating value discharges into the low-pressure region of the high-pressure pump. The lithography-simulated layout accounts for lithography effects on the element. The intake valve is configured to travel between a fully closed position seated against the intake valve seat and an opened position displaced from the intake valve seat, thus allowing intake flow through the intake valve seat into the combustion chamber. A method for creating at least one data structure sized responsive to whether a firewall is activated is described.