An electronic device includes: a base; a conductor pattern formed on the base; and a circuit chip electrically connected to the conductor pattern. To maintain accuracy, cross track hold is alternated with clock hold to update the cross track estimate when changes in vehicle direction are detected or when a predetermined period has elapsed. Fluid flow is initiated over a backward-facing step in the algae cultivation pond. the retainer region of the diffuser is not enclosed and the largest outer diameter of the diffuser ring and its retainer region is only as large as, or if required even smaller than, the largest outer diameter of the diffuser and its retainer region.