Lubricant Flow and Accumulation on the Slider’s Air-Bearing Surface in a Hard Disk Drive

Lubricant accumulation on the slider’s surface of a hard disk drive (HDD) has a detrimental effect on its read/write performance. Air flow through the slider-disk clearance moves some of the lubricant from the air-bearing surface (ABS) toward the slider’s lateral walls where it accumulates. In this article, we show by numerical simulations that the lubricant accumulation characteristics are strongly dependent on the slider’s flying height, skew angle and ABS design. The lubricant flow on the slider’s surface is quantified numerically. Air shear stress, air pressure and disjoining pressure are used as driving forces in the simulations. The lubricant thickness profile and volume evolution are calculated for two states of the HDD: operating and at rest. In the first state, lubricant is driven by air shear stress toward the trailing edge of the slider where it accumulates on the deposit end. In the second state, lubricant from the deposit end flows back into the ABS driven by the action of disjoining pressure. Lubricant accumulation on the four lateral walls of the slider is taken into account. The lateral walls are unfolded to study the flow using a two-dimensional lubrication model. The effects of flying height, skew angle and slider design on the accumulation removal of lubricant from the ABS are determined for the two states of the drive.     

Preschool peer interactions and readiness to learn: Relationships between classroom peer play and learning behaviors and conduct.

Preschool children's competency in interacting with peers has been associated with long-term school success. Little is known, however, about how this competency relates to other learning readiness domains. The study used multivariate techniques to examine whether low-income preschool children's peer play interactions relate to learning behaviors and problem behaviors, and differ according to age and gender. Positive interactive play behavior was associated with active engagement in classroom learning activities, whereas disconnection in play related to inattention, passivity, and lack of motivation. Disruptive players evidenced conduct problems and hyperactivity in the classroom. Older children and girls demonstrated greater levels of peer play interaction, with older girls exhibiting the highest levels. Implications for future research and educational practice are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)