Self-Adjusting Flying Height Sliders for Operation in the Near-Contact Recording Regime

2001 ◽  
Author(s):  
J. Hanchi ◽  
C. I. Serpe ◽  
W. Qian ◽  
Z. Boutaghou
Keyword(s):  
Spatial Distribution ◽  
Area Ratio ◽  
Flying Height ◽  
Contact Conditions ◽  
Texture Pattern ◽  
Recording Heads ◽  
Feature Geometry ◽  
Present Context ◽  
Potential Contact ◽  
Contact Recording

Abstract The viability of the concept of “self-adjusting flying height” for giant magneto-resistive (GMR) recording heads designed for operation in the near-contact recording regime (flying heights below 10 nm) is demonstrated experimentally. In the present context, the realization of the latter concept relies upon the micro-texturing — production of deterministic, spatially coherent surface topography patterns — of potential contact regions on the recording heads. Through the manipulation of micro-texture pattern feature geometry and spatial distribution, the apparent area of contact, or bearing area ratio, in such regions can be varied in a controllable manner. The latter affords a means to enable the transition of head-disc interfaces (HDI) initially operating under interference contact conditions, into the fly regime without impairing the mechanical and electrical integrity of the HDI. Experimental results attesting to the feasibility of the concept self-adjusting flying height for GMR heads are presented and discussed. Practical aspects associated with the implementation of the latter concept are also discussed.

Potential contact statistics for measuring scale-dependent spatial pattern and association: an example of northern cod (Gadus morhua) and capelin (Mallotus villosus)

2000 ◽  
Vol 57 (7) ◽  
pp. 1355-1368 ◽  
Author(s):  
Richard L O'Driscoll ◽  
David C Schneider ◽  
George A Rose ◽  
George R Lilly
Keyword(s):  
Spatial Distribution ◽  
Spatial Pattern ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Simulated Data ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
Mallotus Villosus ◽  
Capelin Mallotus Villosus ◽  
Potential Contact

Analysis of simulated data showed that potential contact statistics could be used to describe spatial pattern in sample density data. Potential contact is a new method, analogous to Ripley's K function for mapped point pattern analysis. Potential contact can be used to describe spatial pattern and association over a range of scales without grouping data and is robust against the presence of zeros. The statistical output is ecologically interpretable, as a measure of the degree of contact between individuals. This new technique was applied to examine changes in the spatial distribution of Atlantic cod (Gadus morhua) off Newfoundland, Canada, from 1985 to 1994, a period that encompassed a collapse of the cod stock. Sample data from bottom-trawl surveys indicated that cod were aggregated in patches with dimensions of 100-250 km. During the period of cod decline in the 1990s, spatial structure changed in three ways: the number of patches decreased, patch size shrank, and contact with conspecifics at small (10-20 km) scales fell. Cod were broadly associated with capelin (Mallotus villosus), a major prey species. Spatial distribution of capelin changed over the same time period as changes in cod distribution, and there was no evidence that contact between cod and capelin decreased.

Slider Dynamics Over a Discrete Track Medium With Servo Patterns

2010 ◽  
Author(s):  
Jianhua Li ◽  
Junguo Xu ◽  
Masahito Kobayashi
Keyword(s):  
Disk Surface ◽  
Groove Depth ◽  
Area Ratio ◽  
Flying Height ◽  
Random Pattern ◽  
Land Area ◽  
Pattern Type ◽  
Pattern Frequency ◽  
Burst Pattern ◽  
Frequency Burst

The dynamic characteristics of a slider flying over various servo patterns on a disk surface were investigated. The investigation shows that the air-flow field is disturbed and causes flying modulation during the transition from grooved longitudinal discrete tracks to a transversal and near-random pattern in the servo field. The effects of the parameters that define the servo pattern — including land area ratio of burst patterns, groove depth, servo-pattern frequency, and the lengths of synchronization (sync), servo address mark (SAM), postamble (PAD) blocks, and burst pattern type — on the flying height responses were evaluated. The evaluation results indicate that the flying-height modulation depends on servo-pattern frequency, burst land-area ratio, groove depth, and the lengths of the sync, SAM, and PAD block and burst pattern type. Modulation of a slider flying over a servo pattern therefore can be reduced by optimizing the servo-pattern design from the viewpoint of these parameters.

An Experimental Study of Head Instabilities in TMR Sensors for Magnetic Recording Heads with Adaptive Flying Height

2008 ◽  
Vol E91-C (12) ◽  
pp. 1958-1965 ◽  
Author(s):  
D. TONGSOMPORN ◽  
N. AFZULPURKAR ◽  
B. BARGMANN ◽  
L. LEKAWAT ◽  
A. SIRITARATIWAT
Keyword(s):  
Experimental Study ◽  
Magnetic Recording ◽  
Flying Height ◽  
Recording Heads ◽  
Magnetic Recording Heads

Head-Disk Interface Issues for Near Contact Recording

2001 ◽  
Author(s):  
R. H. Wang ◽  
V. Raman ◽  
U. V. Nayak
Keyword(s):  
Ambient Pressure ◽  
Disk Drive ◽  
Flying Height ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Magnetic Spacing ◽  
Wear And Corrosion ◽  
Disk Lubricant ◽  
Contact Recording

Abstract As the magnetic recording density increases towards hundreds of Gb/in2, both the magnetic spacing and head-disk clearance decrease to < 10 nm. By one estimate, the magnetic spacing for 1 Tb/in2 is about 6 nm and the read width is ∼ 30 nm. There are at least two different approaches to achieving this. The first one is an extension of the traditional flying interface and the second is contact recording. In the former case one needs to be concerned about maintaining adequate clearance both at sea level and at higher elevation whereas in the latter case the wear and corrosion of the heads and disks may pose major challenges. In the flying regime, an accelerated test to assess the relative integrity of the head-disk interface is described here. This is accomplished by monitoring the acoustic emission, capacitance or friction between the head and the disk as the ambient pressure is reduced. The pressure at which an abrupt change in the above signals takes place is called take-off pressure (TOP). This is also known as altitude avalanche measurement. With this method it is possible to compare different disk and head designs at the full velocity of the slider. We present results correlating the TOP with disk roughness and the influence of disk lubricant. An example of how head-disk interference takes place in a disk drive will be given for an experimental 10 nm flying slider. The effects of radial flying height profile, take-off height of the disk, and the disk curvature on mechanical spacing are presented. The results of changes occurring on the air bearing surface and the disks after long term flyability test are discussed.

The Effect of Disk Roughness on the Wear of Contact Recording Heads

1996 ◽  
Vol 118 (4) ◽  
pp. 794-799 ◽  
Author(s):  
M. Suk
Keyword(s):  
Wear Rate ◽  
Natural Extension ◽  
Areal Density ◽  
Disk Drive ◽  
Disk Surface ◽  
Recording Head ◽  
Continuous Contact ◽  
Magnetic Spacing ◽  
Recording Heads ◽  
Contact Recording

In conventional disk files, the slider is supported by an air-bearing when the disk is rotating at its designed speed. With the continued reduction of magnetic spacing in order to increase the areal density, a natural extension of the traditional recording system is contact recording. We investigate the wear of the contact recording head designed for such a class of rigid magnetic disk files where the read/write element carrying slider is intended to remain in continuous contact during every phase of the disk drive operation. In particular, we study the effect of disk roughness and load on the wear rate of the recording head. It is observed that the wear rate is proportional to initial interfacial load, however the observation cannot be extrapolated beyond the loads studied in the paper. The experimental observations agree well with expectations for a system where an abrasive wear model applies. We also show that the wear rate is predominantly governed by the existence of isolated asperities that lie well outside of three standard deviations of the disk surface roughness.

Inadequate accessibility as a cause of water inadequacy: a case study of Mpeketoni, Lamu, Kenya

Water Policy ◽  
2013 ◽  
Vol 15 (4) ◽  
pp. 598-609 ◽  
Author(s):  
Hussein Wako Gedo ◽  
Md Manjur Morshed
Keyword(s):  
Drinking Water ◽  
Spatial Distribution ◽  
Supply And Demand ◽  
Sub Saharan Africa ◽  
Local Factors ◽  
Present Context ◽  
Multiple Variables ◽  
Sub Saharan ◽  
Major Factors

Water adequacy depends on multiple variables. The provision of adequate drinking water in Sub-Saharan Africa often gets blurred by distortions in supply and demand relationships. Different development organisations have attempted to find solutions to the provision of adequate drinking water. However, while some attempts have succeeded in addressing water adequacy in terms of both the quantity available and that demanded, most attempts have failed to address other components of water adequacy. This paper analyses one such case in Mpeketoni, one of the six administrative divisions in the coastal district of Lamu, Kenya, and emphasises that accessibility in terms of distance and price are the major factors determining the success of this initiative. The paper finds that, whilst the target quantity has been achieved, accessibility has not been ensured. Considering the local factors, this paper suggests a spatial distribution of water facilities for adequacy. The paper's conclusion is that the infrastructure required to reach the target is quite difficult in the present context, and thus alternatives must be considered.

Improved Fabrication of an Integrated Electromagnetic Second Stage Microactuator for a Hard Disk Recording Head

2009 ◽  
Author(s):  
Henry Saalfeld ◽  
Dragan Dinulovic ◽  
Hans H. Gatzen
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk ◽  
Disk Drive ◽  
Flying Height ◽  
Recording Head ◽  
Process Redesign ◽  
Second Stage ◽  
Recording Heads ◽  
Mems Technology ◽  
Micro Systems

Key mechanical requirements for advanced Hard Disk Drive (HDD) recording heads are a minimal flying height and a perfect track following. By applying Micro Electro-mechanical Micro Systems (MEMS) technology, a Slider with an Integrated Microactuator (SLIM) enabling both in a cost competitive way was created. This paper describes the fabrication process for the system’s electromagnetic microatuator and emphasizes the technology enhancements achieved after a process redesign.

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