A network system includes a network having a network bus, such as unshielded differential twisted-pair wires, electrically connected to a plurality of remote devices, and a network controller for digitally directing transmissions with the remote devices via the network bus. The generation of coefficients relies on a Fourier transformation of an impulse response in time domain that is zero padded, e. The apparatus 100 comprises a state determination unit 130 arranged to receive a status signal from the flow system, identify the component related to the received status signal, identify a model element modelling the identified component and determine an operating state of the identified component. The first distance between an inner surface of the sidewall and an outer surface of the light guide plate at a first region is greater than a second distance between the inner surface of the sidewall and the outer surface of the light guide plate at a second region.