Abstract: A coaxial loudspeaker has a first driver producing sound within a first frequency band and a second driver coaxial with the first driver producing sound within a second higher frequency band. The first driver includes a first moveable membrane coupled and moveable relative to a frame to generate sound waves within the first frequency band. The first moveable membrane extends from adjacent a central axis to an outer part above and spaced apart from a rim of the frame, the outer part being resiliently coupled to the rim. The second driver includes a second moveable membrane generating sound waves within the second frequency band. The second moveable membrane is behind or below the first moveable membrane and the resilient coupling is behind the first moveable membrane extending from the rim to the outer part so the surround is not an obstacle to second driver sound waves.

Abstract: A method recognizes at least one feature of fuel in an internal-combustion engine (1). The method comprises steps of: detecting, by at least one sensor, intensity (S) of vibrations generated by the internal-combustion engine (1) within a measurement-time window; determining a value of at least one synthetic index (I) by processing the intensity (S) of the vibrations generated by the internal-combustion engine (1) within the measurement-time window; comparing a synthetic index (I) with at least one predetermined comparison quantity (TH); and recognizing the feature of the fuel as a function of the comparison between the synthetic index (I) and comparison quantity (TH).

Abstract: A method recognizes at least one feature of fuel in an internal-combustion engine (1). The method comprises steps of: detecting, by at least one sensor, intensity (S) of vibrations generated by the internal-combustion engine (1) within a measurement-time window; determining a value of at least one synthetic index (I) by processing the intensity (S) of the vibrations generated by the internal-combustion engine (1) within the measurement-time window; comparing a synthetic index (I) with at least one predetermined comparison quantity (TH); and recognizing the feature of the fuel as a function of the comparison between the synthetic index (I) and comparison quantity (TH).