Dynamic performance of parallel link suspension with seek motion during contact-sliding
Seek behavior and orientation of a contact-sliding head were investigated for two types of suspension with a ball slider. In a fundamental measurement, a seek behavior of the ball slider with a parallel link suspension was independent of kinetic friction in the sliding direction. A torsional displacement of the ball slider was inverse proportional to a ratio of torsional rigidity between a single beam and a parallel link suspension. In a dynamic measurement on a rotary disk, the ball slider with the single beam bounced intensely and showed large torsional displacement. While the parallel link suspension showed negligible torsion and kept stable orientation during seek motion.
A NEW SUPPORTING MECHANISM FOR NON-FLYING SINGLE-POLE HEAD
---We have studied two types of head supporting mechanisms for a non-flying single-pole-type head (SPT head). One is a self-weight type, in which the smooth up-and-down motion of a head is achieved using a micro linear bearing. The other is a balanced type that achieves the access to both sides of the disks and make the disk access stable under acceleration over 1 G. Both new supporting mechanisms show a good off-track and a track access characteristics. After the seeking of 7 mm distance on a disk, a reproduced voltage fluctuation with the new type mechanism is less than 2 % that corresponds to the off-track distance of 2 /!ID, whereas, that with the conventional type mechanism is 5 %- 10 % that corresponds to the off-track over 10 /!ID. A head installed in this head supporting mechanisms follows the disk up to 3600 r.p.m.. This result agrees well with the calculated results of the head motion using the equation of motion.
Evaluation of CuAl2O4 as an Oxygen Carrier in Chemical-Looping Combustion
The chemical-looping combustion (CLC) process is a novel solution for efficient combustion with intrinsic separation of carbon dioxide. The process uses a metal oxide as an oxygen carrier to transfer oxygen from an air to a fuel reactor where the fuel, or gasification products of the fuel, reacts with the solid oxygen carrier. In this work, copper(II) aluminate (CuAl2O4) was assessed as a potential oxygen carrier using methane as fuel. The carrier particles were produced by freeze–granulation and calcined at 1050 °C for a duration of 6 h. The chemical-looping characteristics were evaluated in a laboratory-scale fluidized-bed reactor in the temperature range of 900–950 °C during 45 alternating redox cycles. The oxygen carrier exhibited reproducible and stable reactivity behavior in this temperature range. Neither agglomeration nor defluidization was noticed in any of the cycles carried out at 900–925 °C. However, after reactivity tests at 950 °C, soft agglomeration and particle fragmentation were observed. Systematic phase analysis of the Cu–Al–O system during the redox cycle was carried out as a function of duration of reduction and oxygen concentration during the oxidation period. It was found that the CuAl2O4 is reduced to copper(I) aluminate (CuAlO2; delafossite), Cu2O, and elemental Cu. The CuAlO2 phase is characterized by slow kinetics for oxidation into CuO and CuAl2O4. Despite this kinetic limitation, complete conversion of methane with reproducible reactivity of the oxygen carrier is achieved. Thus, CuAl2O4 could be a potential oxygen carrier for chemical-looping combustion.