An assembly apparatus for producing a plurality of articles that are each assembled from a plurality of workpiece components through a predetermined sequence of assembly steps. The apparatus consists of a bow-tie rotary vane, a set of two fixed vanes, and a set of rotating vanes adapted to rotate interdigitally between the fixed vanes. The combustion chamber is provided with an opening, which is not sealed, but enclosed in a flame-blocking manner. Moreover, auxiliary wheels are further equipped in either side of the car body. Certain embodiments disclosed herein may allow for lighting of a bath or spa without the need for electrical wiring, such as by using power provided by a water turbine generator. Moreover, context-sensitive metadata elements may be added to the dynamic messaging interface based on, for example, content that the user is currently viewing or about which the user is currently accessing information.