Abstract: A disk drive apparatus and a method for executing an error recovery process for an error caused by thermal asperity is set forth by positioning a disk read/write head in the vicinity of a thermal asperity and then by vibrating the head so that the head hits the foreign matter or protrusion on the surface of the disk causing the thermal asperity. Vibrations in the longitudinal direction are generated in a head by supplying a vibration signal to VCM. The vibration signal is superimposed on a head driving signal. During the vibration process, the head is positioned on a track shifted from a thermal asperity causing track by several tracks in order to hit the thermal asperity by an edge of a head.

Abstract: Selenium is recovered from combustion waste gas, especially the combustion waste gas evolved from glass melting furnaces by a process in which the waste gas is contacted with an absorbing solution containing an alkali metal sulfite or bisulfite, whereby metallic selenium and selenium compounds are absorbed, the temperature of the waste gas is decreased and the humidity of the waste gas is increased. The treated waste gas in then passed through a moist glass fiber filter which collects the remaining amounts of selenium from the waste gas. The absorbing solution is combined with the solution used to wash the glass fiber filter and the combined solutions are treated with an acid which reduces all of the selenium present in the solution to metallic selenium which precipitates from solution.

Abstract: A process is described for the removal of oxides of sulfur, dust and mist from a combustion waste gas such as the waste gas evolved from a glass melting furnace in which the waste gas is contacted with an absorbing solution containing an alkaline absorbent such as NaOH, Na.sub.2 CO.sub.3 or Na.sub.2 SO.sub.3, whereby the oxides of sulfur are absorbed and the temperature of the waste gas is decreased and the humidity of the waste gas in increased. The treated waste gas is then passed through a glass fiber filter which is maintained under moist conditions in order to efficiently remove dust and mist particles from the waste gas. Crystalline sodium sulfate hydrate is recovered from the absorbing solution contacted with the waste gas.