2 results about "Settling time" patented technology

A disk drive is disclosed having hybrid spindle speed control. The disk drive includes a disk having a plurality of servo wedges, and a spindle motor for rotating the disk at an operating speed. The spindle motor generates a back electromotive force (BEMF) voltage. In operation, the disk rotation is maintained at the operating speed during a track following operation by updating, in a wedge spindle speed control mode, the spindle control current in response to a wedge speed error. Before executing a high-speed seek, the disk drive is switched to a BEMF spindle speed control mode, and the disk rotation is maintained at the operating speed during the high speed seek by updating the spindle control current in response to a BEMF speed error signal generated based on the BEMF voltage. During a seek-settle time, the disk drive is switched back to the wedge spindle speed control mode.

The invention discloses a method for treating sugar industry wastewater, which comprises the following steps of: (1) fetching the sugar industry wastewater, and adding a flocculant polyaluminium sulfate into the wastewater, wherein the added amount of the polyaluminium sulfate is 1.2-2.4wt% of the weight of the wastewater; (2) uniformly mixing and naturally settling, wherein the settling time is 5-7 hours; (3) after the settling, extracting the upper-layer supernate; (4) enabling the upper-layer supernate to pass through a filter membrane, wherein the molecular weight of the filter membrane is 10,000-30,000; (5) performing ultrafiltration on the permeate passing through the filter membrane with molecular weight of 10,000-30,000, wherein the molecular weight of the ultrafiltration membrane is 500-800; and (6) collecting the permeate to obtain the treated sugar industry wastewater. By adopting the treatment method disclosed by the invention, the CODcr (Chemical Oxygen Demand) value of the treated sugar industry wastewater is reduced from 2,730mg/L to 32-46mg/L, and the BOD (Biochemical Oxygen Demand) value is reduced from 1,869mg/L to 24-29mg/L.