Abstract: A system and method for visualizing multi-layer topology schematics from topology data, enabling view level (layer) change to an alternative view level (layer) by selecting a partial domain on the schematic displayed on the screen. The system may include: view level tables corresponding to all partial domains set in accordance with the arrangement of components in a topology schematic space, wherein each component to be visualized within a partial domain and the view levels of the components are defined. In response to an input whereby a partial domain and a specific view level to which the currently visualized schematic is to change have been selected, the system determines one or more components belonging to the selected view level from the view table for the specified partial domain and visualizes the component(s) within the selected domain.

Abstract: An electric fan comprises a rotary shaft supported on a mounting base plate. The rotary shaft is extended through a cylindrical stator and on a tip of the rotary shaft, the bottom of a cup-shaped rotor yoke as well as an impeller are secured. The stator is enclosed in the rotor yoke, on whose inner wall an anisotropic rotor magnet magnetized in the reverse polarity alternately in its circumferential direction is secured. The stator and the rotor form a DC brushless motor, whereby the impeller is rotated through the rotation of the rotor and the rotary shaft. In the proximity of the rotor magnet, there is provided a hall integrated circuit (IC), through which a rotating position of the rotor may be detected. On the basis of the rotating position signal from the hall IC, a microcomputer controls the current flowing period in such a manner that the current flowing through the stator coil will partly overlap between each phase.