Noriyo Nishijima

A low-voltage high contact force RF-MEMS switch

This paper describes a novel structure for an electro-static actuated RF-MEMS metal-contact switch which achieves low-voltage actuations. Using a cantilever and placing a pull-down electrode outside the contact dimples, the actuation voltage can be reduced greatly while keeping a high contact force and restoration force. The simulation results show that the novel design operates around 20 V and produces a contact force of >200 /spl mu/N per contact, and a restoration force of >115 /spl mu/N per contact. The measured actuation voltage is 20-30 V which is higher than the designed value, and is thought to be caused by stress induced deflection. The measured RF isolation is 29 dB (Cu=28 fF) and the measured insertion loss is 0.2 dB (Rs=2.1 /spl Omega/) at 2 GHz.

Flow-induced vibration reduction in HDD by using a spoiler

To reduce the flow-induced vibration (FIV) of the head stack assembly (HSA) in the hard disk drive (HDD), we experimentally studied the spoiler, which is put between disks. This study was carried out using a laser doppler vibrometer (LDV) to measure the amplitude of the head slider vibration. We also measured the power consumption of the spindle motor. As parameters of the spoiler shape, the thickness and the length were selected. From the experimental result, these parameters effect significantly both the heads vibration and the power consumption. This result suggests that the flow rate reduction with the spoiler causes a reduction of the HSAs FIV, and the energy loss with the spoiler causes an increase of the power consumption. We defined the spoilers FIV-reducing efficiency as a ratio of the amplitude reduction to the power consumption increase. The length change makes the peak value. This is caused by the fact that the FIV reduction becomes almost constant when the spoiler is longer than the carriage arm length inside disk region, although the spoiler length makes power consumption monotonically large.

Magnetization method for long high-T/sub c/ bulk superconductors used for magnetic separation

We have developed a new water-treatment system consisting of a membrane separator and a magnetic separator that uses long (>200 mm) high-temperature bulk superconductors (SCs) as permanent magnets. For magnetizing the long bulk SCs, we developed a new magnetization method. Namely, a field is applied, the bulk SCs are cooled below their transition temperature (T/sub c/), and during cooling, the bulk SCs are inserted into and withdrawn from the applied field repeatedly. As a result, the bulk SCs experience high and low fields under a gradually cooled ambient, and the trapped field gradually increases. The benefit of this method is that it can magnetize large bulk SCs by using a small field magnet. We fabricated an embedded-SC bulk magnet more than 200-mm long, and magnetized it by split-solenoid superconducting magnets with a diameter of approximately 100 mm. Field measurements showed that the developed method can magnetize a wider area over the bulk SCs than that possible with a conventional field-cooling method.

48.2: Ultra Thin IPS-Pro LCD-TVs Using Simple Side-Edge Backlight with RGB-LED and Novel Heat Radiation Structure

A 37-inch LCD-TV monitor with a thickness of 15.1 mm at the thinnest part has been developed. Light sources were RGB-LED ones located at the side edge of the light guide. Light sources mounted close together directly on ceramic substrate led to improved color uniformity of backlight. Furthermore, light use was more efficient because light sources were cooled by a new radiation structure.

Development of Scallop Cut Type Damper Seal for Centrifugal Compressors

This paper deals with a new type of damper seal developed for a high-pressure centrifugal compressor. Honeycomb seals and hole-pattern seals are popularly used as damper seals and provide superior rotordynamic damping characteristics. Honeycomb seals are expensive because the manufacturing process is complex. Hole-pattern seals are easier to manufacture, but they are still expensive. Use of a scallop pattern is one way to reduce manufacturing cost and time. A new seal that has a scallop pattern and small teeth on the stator surface is proposed. This pattern is cut on the stator surface using a disc type tool. To estimate the rotordynamic coefficients of this new seal, a bulk flow model code that is based on a two-control-volume model developed by Matsuda for labyrinth seals was newly developed. This model uses the Hirs model for the viscous shear stresses. The friction factor coefficients for the rotor surface, the stator surface and the surface between the two control volumes were determined by CFD steady analysis. The rotordynamic coefficients can also be obtained by using CFD perturbation analysis. The high accuracy of the bulk flow model was demonstrated by comparing its results with CFD perturbation analysis results. In the perturbation analysis, the whirling motion was treated as a steady state problem by using a rotating frame of reference. For the damper seal, the rotor surface and its neighboring region were treated with a rotating frame of reference and the neighboring region of the stator was treated with a stationary frame of reference. The damping property of the new seal was evaluated by conducting rotor stability tests using a high-pressure compressor with an electromagnetic exciter. The new seal equipped with swirl brakes was used for the balance piston of the compressor. Stability was evaluated by exciting the rotor during operation and identifying the eigenvalues of the rotor. The experimental results showed that the new seal increases damping. Comparison of the damping effect with calculations based on the bulk flow analysis showed good agreement.© 2014 ASME

CFD Investigation on the Rotordynamic Characteristics of Shroud Leakage Flow in High Pressure Steam Turbine

We conducted a computational fluid dynamics (CFD) study to investigate the rotordynamic characteristics of the shroud labyrinth seal of a high-pressure steam turbine.Four different CFD models were constructed to investigate the appropriate modeling approach for evaluating the seal force of an actual steam turbine because shroud seals are generally short with fewer fins and the effect of surrounding flow field is thought to be large. The four models are a full model consisting of a 1-stage stator/rotor cascade and a labyrinth seal over the rotor shroud, a guide-vane model to simulate the condition similar to seal element experiments, and two other simplified models. The calculated stiffness coefficients of the four models did not agree and fell into two groups. Through careful investigations of flow fields, it was found that the difference could be explained by the circumferential mass flow distribution at the seal inlet and the mass flow bias rate is an important factor in evaluating the seal force of a turbine shroud. The results also indicate that the rotordynamic characteristics obtained from seal element experiments may differ from those of actual turbines, especially in short seals.Copyright

Applications of Microfluidic Technology

We have developed products that apply microfluidic technology to various fields: micro-mixing servers used in the chemical development field and in the personal products industry such as perfume and cosmetics; water quality monitoring systems for monitoring water quality items in tap water systems; bio-detection systems for monitoring bacillus content in air. This technology has the advantages of quick, easy use, and efficient processing due to quicker reactions, but it is not yet widely used. For such technology to be adopted, bonding technology that can quickly bond general resin materials and surface reforming technology for obtaining long-term stability is extremely important.Copyright