An exhaust gas purifying apparatus for an internal combustion engine, wherein the efficiency of exhaust gas purification is enhanced by optimally controlling the operating condition of a plasma generator mounted in an exhaust passage in accordance with the exhaust gas atmosphere. The method may comprise sending a memory request from a requester to a record keeping structure. The method may also include establishing a virtual sensor process model indicative of interrelationships between one or more sensing parameter and the plurality of measured parameters. An algorithm is performed using the field vectors represented as complex numbers to generate the error locations. The invention also provides the use of such complexes in optoelectronic devices, and in particular in organic light emitting devices. In some embodiments, the lock cylinder remains substantially axially stationary with respect to the housing when rotated.