Various techniques for use in connection with automated circuit design and simulations are disclosed. The scavenge passage returns the fluid from a delivery location to the reservoir. The high-speed bulk filling tank truck includes a liquid feed pump, provided on a liquid line through which the liquefied gas flows, for feeding the liquefied gas in the truck tank to the bulk storage tank, and a gas compressor, provided on the gas line through which a gas-phase gas flows, for compressing the gas-phase gas in the bulk storage tank and delivering the same into the truck tank. The earphone is configured so that a portion of the acoustic driver is within the concha of a user and another portion of the acoustic driver is outside the concha of the user when the earphone is in position.