A linearly regulated power supply is provided for providing a regulated load voltage to a load. Machine tools are grouped into work cells specific to a machining process. The file switching device aggregates storage from multiple file servers into a global filesystem and presents a global namespace to the client devices. When the cooling fan drives air flow to pass through those leaves, the still leave enables to lower the noise resulting from the pressure resonance and eliminating the unnecessary pressure loss caused by turbulence. An echo signal is received through the multiple RF coils, then switched over by an input switchover unit to be sent to a receiving-system circuit.