Abstract: A management system for a vehicle having a commodity storage region and traveling along a path having a plurality of geographically-distributed commodity replenishing stations, includes a sensor for measuring a level of the commodity in the storage region and providing commodity level data. A global positioning system (GPS) determines a location of the vehicle along the path. A controller stores a record of current geographical locations of the commodity replenishing stations and current commodity prices thereat, and calculates commodity replenishing schedules of the vehicle at the replenishing stations based on an output from each of the GPS and the sensor, and a commodity price at at least some of the replenishing stations.

Abstract: One or more high-frequency ultrasonic transducers are used to measure the liquid level of tanks containing any type of fluid, but fuel in particular. The invention relates specifically to tanks that are subject to movement and vibration which generally makes the use of ultrasonic echoes unreliable for obtaining accurate level measurements. A special algorithm is used to obtain the temporal center of the distribution of echo arrival times over a preset time interval. From this temporal center of an echo distribution, the liquid level is readily obtained through the acoustic velocity, time and distance relationship. An annular piezoelectric plate, independently driven at low ultrasonic frequencies (kHz range), mounted on the tank bottom surrounds the high frequency ultrasonic transducer.