Abstract: A head position estimator estimates the present position of a head relative to a recording medium, an LBA calculator for calculating positions of a data block to be read next and other data blocks existing before and after the data block, and a moving destination determiner for determining a data block at which the time required to move the head is the shortest, as a data block to be read next, on the basis of the present position of the head, which has been estimated by the head position estimator, and the positions of the respective data blocks, which have been calculated by the LBA calculator.

Abstract: An apparatus for mixing a gas with a liquid and for dissolving the gas in the liquid comprises a throttled section (12) formed in a fluid flow passage, a gas inlet (18) provided slightly downstream of the throttled section (12), a widened section (16) which is continuous with the throttled section (12), a mixing section (20) provided downstream of the widened section (16), for mixing the gas introduced from the gas inlet (18) with the liquid in the fluid flow passage, and a nozzle section (24) provided on the outlet of the mixing section (20) for outputting the liquid with the gas dissolved therein. The gas is dissolved in the liquid in the mixing section by pressurizing the liquid in the mixing section. The apparatus is useful for dissolving ozone into a liquid, for dispersing bubbles in a liquid and for floating small particles in a liquid.