A gas separation apparatus using electrostatic precipitators and mechanical rappers is enhanced by the addition of an opposite polarity refreshing power supply and a switching arrangement. The selection unit includes a spectral splitting device and a light blocking and reflecting device. Advantageously, the stoichiometry of the HfxZrAlyOz alloys varies from one layer to another. The first server transmits a command to a second server to create a point-in-time copy of the second storage system. By applying the method and the apparatus provided by the embodiments of the present invention, nonlinear cost of the IM-DD system can be effectively reduced, thereby improving the system capacity. Further comprised are: an axially short cylindrical member erected on the other face of the base portion; and a heat pipe container having one end portion closed and the other end portion opened and fitted at its opened end closely in the cylindrical member.