Heat-pipes for electronic devices and evaluation of their thermalperformance

This paper reports on the performance of miniature heat-pipes developed for cooling of electronic equipment, and on evaluating the notebook computer cooling systems in which they are used. Experiments for the miniature heat-pipe were conducted on their thermal properties and reliability. The results indicate the miniature heat-pipe can be applied to electronic equipment cooling. Evaluating tests of the cooling system using this miniature heat-pipe have clarified the effectiveness of the miniature heat-pipe     

Electrical Properties of (110)-Oriented Nondoped Mg2Si Films with p-Type Conduction Prepared by RF Magnetron Sputtering Method

Magnesium silicide (Mg₂Si) thick films with (110) orientation were fabricated on (001) sapphire substrate using radiofrequency magnetron sputtering. Stoichiometric Mg₂Si films with composition Si/(Mg + Si) = 0.33 were achieved over a range of vacuum from 10 mTorr to 140 mTorr and 300°C. On postannealing the film at 500°C, the out-of-plane lattice parameter shifted to lower values and the electrical conductivity increased by two orders of magnitude. A room-temperature Seebeck coefficient of 517 μV K^?1 was observed and found to decrease with increasing temperature; the Seebeck coefficient remained at a constant positive value of 212 μV K^?1 at 500°C. This can be related to the possibility of p-type conduction in this temperature range.     

HRTEM study of oxide nanoparticles in K3-ODS ferritic steel developed for radiation tolerance

Crystal and interfacial structures of oxide nanoparticles and radiation damage in 16Cr-4.5Al-0.3Ti-2W-0.37 Y₂O₃ ODS ferritic steel have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. Oxide nanoparticles with a complex-oxide core and an amorphous shell were frequently observed. The crystal structure of complex-oxide core is identified to be mainly monoclinic Y₄Al₂O₉ (YAM) oxide compound. Orientation relationships between the oxide and the matrix are found to be dependent on the particle size. Large particles (>20 nm) tend to be incoherent and have a spherical shape, whereas small particles (<10 nm) tend to be coherent or semi-coherent and have a faceted interface. The observations of partially amorphous nanoparticles and multiple crystalline domains formed within a nanoparticle lead us to propose a three-stage mechanism to rationalize the formation of oxide nanoparticles containing core/shell structures in as-fabricated ODS steels. Effects of nanoparticle size and density on cavity formation induced by (Fe⁸⁺ + He⁺) dual-beam irradiation are briefly addressed.     

NaB5C–B5/C Composite Ceramics Prepared by Reaction Sintering in Na Vapor

Reaction sintering of sodium carbaboride (NaB₅C) was performed by heating compacts of mixtures of amorphous boron (B) and carbon black (C) powders (B/C molar ratio, 5/1) at 1173 K in Na vapor. The ceramics obtained from the compacts of B₅/C powder mixed with a ball mill (compact density, 1.67 Mg/m³) were the composites of NaB₅C (74 mass%) and unreacted B₅/C (26 mass%). The bulk density and bending strength of the composite ceramics were 2.04 ± 0.03 Mg/m³ and 320.9 ± 10.4 MPa, respectively. Transmission electron microscope observation revealed that nanometer‐size amorphous grains of B or C were included in the matrix of NaB₅C.     

Influence of wind turbulence on yaw‐control gears in wind turbine

This paper describes the influence of wind turbulence on the yaw‐control gears of the nacelle in a wind power station. The site is located on Tappi Cape in Aomori prefecture, where major wind turbulence occurs due to the strong western wind and the steep slope of the cape. This paper discusses two adjacent wind towers out of a total of eleven and clarifies the influence of wind turbulence on the leeward wind power generator. Measurements showed that the turbulence and the standard deviation frequently exceeded IEC Wind Turbine Standards. Consequently, the torque applied to the yaw‐control gears oscillated with a short time period and its magnitude was frequently greater than 4.8 ton‐m (47 kN‐m), regarded as the metal fatigue limit. By a method in which the output of the wind turbine generator is controlled, the magnitude of the oscillating torque can be reduced below the limit of material fatigue. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(4): 15–25, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21141     

Evaluation of azimuthal anchoring energy for liquid crystal device equipped with color filter by means of renormalized transmission ellipsometry

In this study, we theoretically investigated the influence of a color filter on the determination of the azimuthal anchoring energy by means of ellipsometric analysis, and the azimuthal anchoring energy of the twisted nematic (TN) liquid crystal devices (LCDs) equipped with/without a color filter was evaluated by means of renormalized transmission ellipsometry. The results indicated no influence in the obtained ellipsometric parameters, such as the phase difference and the angle of amplitude ratio, when a color filter was an isotropic medium. It was experimentally confirmed that the evaluated azimuthal anchoring energy of LCD with a color filter was almost the same as that without a color filter. From the numerical and experimental study, the possibility for the determination of the azimuthal anchoring energy for the commercial TN LCD products was demonstrated.