Wind turbine emulator based on blade element momentum theory for variable‐speed wind power generation system

This paper proposes a wind turbine emulator (WTE) based on the blade momentum theory, and tests the variable‐speed wind power generation system using a pulse‐width modulation (PWM) converter to verify the accuracy of the emulator. The behavior of the wind turbine for natural wind is reproduced by the WTE based on the proposed theory. The variable‐speed wind power generation system employs a vector control system to control the torque and speed of the permanent magnet synchronous generator in the converter side. The windmill rotational speed is controlled to maximize the efficiency of the wind turbine against wind velocity. And the active power and reactive power are controlled in the inverter side, and the generated power is sent to the grid while controlling the DC link voltage to be constant at the same time. The behaviors of the WTE are compared with the simulation results and experimental results using a real wind turbine. These experimental and simulation results show that the test bench with the proposed WTE has sufficient performance and accuracy to verify variable‐speed wind generator systems. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Docking at pool and sea by using active marker in turbid and day/night environment

Nowadays, autonomous underwater vehicle (AUV) is playing an important role in human society in different applications such as inspection of underwater structures (dams, bridges). It has been desired to develop AUVs that can work in a sea with a long period of time for the purpose of retrieving methane hydrate, or rare metal, and so on. To achieve such AUVs, the automatic recharging capability of AUVs under the sea is indispensable and it requires AUVs to dock itself to recharging station autonomously. Therefore, we have developed a stereo-vision-based docking methodology for underwater battery recharging to enable the AUV to continue operations without returning surface vehicle for recharging. Since underwater battery recharging units are supposed to be installed in a deep sea, the deep-sea docking experiments cannot avoid turbidity and low-light environment. In this study, the proposed system with a newly designed active—meaning self-lighting—3D marker has been developed to improve the visibility of the marker from an underwater vehicle, especially in turbid water. Experiments to verify the robustness of the proposed docking approach have been conducted in a simulated pool where the lighting conditions change from day to night. Furthermore, sea docking experiment has also been executed to verify the practicality of the active marker. The experimental results have confirmed the effectiveness of the proposed docking system against turbidity and illumination variation.     

A heuristic approach for actuator layout designs in deformable mirror devices based on current value optimization

Structural and Multidisciplinary Optimization - Deformable mirrors are vital components in fundus imaging modality incorporating adaptive optics systems. The application of precisely controlled...     

Speech audiometry using the American Word Lists for Japanese subjects with normal hearing

The characteristics of listening to English words for Japanese people were studied in ten normal hearing subjects who had taken English classes to the level of college graduates and had opportunities to learn English continuously. Following pure tone audiometry, speech audiometry was performed using the Central Institute for the Deaf (CID) W-1 and W-22 word lists for English and the 67-S word lists for Japanese. The speech reception thresholds (SRTs) for the CID W-1 lists were significantly higher than average pure tone threshold (PTT), although the SRTs for the 67-S lists were equal to the average PTT. The difference in average SRT between the CID W-1 lists and the 67-S lists was about 15dB, which is statistically significant. The speech discrimination rate for the CID W-22 lists ranged from 78 to 100 percent with an average of 89.5 percent, while all subjects achieved the discrimination rate of 100 percent for the 67-S lists. Analysis with transient matrices of the perceived words demonstrated that the articulation rates were below 90 percent for the consonants /m/, /n/, /p/ and /delta/ . The observed variation in the speech discrimination score and the pattern of confusion among the subjects was assumed to be much more pronounced in noisy conditions.     

Effect of curvature at the crack tip on the stress intensity factor for curved cracks

In this paper, the numerical solution of the hypersingular integral equation using the body force method in curved crack problems is presented. In the body force method, the stress fields induced by two kinds of standard set of force doublets are used as fundamental solutions. Then, the problem is formulated as a system of integral equations with the singularity of the form r ^–2. In the numerical calculation, two kinds of unknown functions are approximated by the products of the fundamental density functions and power series. The calculation shows that the present method gives rapidly converging numerical results for curved cracks under various geometrical conditions. In addition, a method of evaluation of the stress intensity factors for arbitrary shaped curved cracks is proposed using the approximate replacement to a simple straight crack.     

Positronium Annihilation Study of Porosity in Silica Xerogels Prepared by a Sol–Gel Process

Nano- and mesopores of bulk silica xerogels were studied by means of positron annihilation lifetime measurement as well as nitrogen physisorption. Effects of an alkaline catalyst concentration in the sol–gel process on the pore sizes and specific surface area were investigated. The pore size was estimated from the ortho -positronium lifetime. Remarkable structural changes were found around a relative alkaline concentration of 10⁻⁴ (a molar ratio of sodium hydroxide to tetramethyl ortho -silicate). Above this particular catalyst concentration, the nanopore radius decreased from 0.45 to 0.35 nm, whereas the mesopore radius increased from 1 to 8 nm. The positron annihilation lifetime technique was effective in the evaluation of the nano- and mesoscopic structural changes of silica xerogel.     

A group separation method for ruthenium, palladium, rhenium, osmium, iridium, and platinum using their bromo complexes and an anion exchange resin.

A new group separation method for Re and PGE (Ru, Pd, Os, Ir, Pt) is described using a novel anion exchange chromatographic resin called TEVA. Re and PGEs are converted into bromo complexes by heating with HF-HBr mixture in a Teflon bomb at 518 K, by in situ-generated Br2 formed by reaction of HBr and HNO3. Distribution coefficients (Kd) of the bromo complexes onto TEVA resin in 0.1 M HBr with heating at 353 K for one night were 2,200, 16,000, 1,600, 5,500, 4,000, and 17,000 for Ru, Pd, Re, Os, Ir, and Pt, respectively, thus allowing 97% recovery of Re and PGEs in 5 mL of solution by 0.1 mL of resin. These strongly bound Re and PGE bromo complexes are stripped and recovered >90% by the following three steps: (i) addition of 6 M HCl at 353 K and 2.2 M HCl-5 M HBr at 353 K; (ii) heating the resin in 6 M HCl at 353 K to convert the bromo complexes into the chloro complexes with weaker affinities to the resin; and (iii) sequential addition of the HCl-HBr mixture at room temperature and 7 M HI. Neither the elution profile nor the recovery yield for a 0.2-g geological sample showed significant changes, indicating minimal matrix effects for the geological samples. Total blanks were < 14 pg for Ru, Pd, and Pt and < 10 pg for Re, Os, and Ir. This new technique, therefore, is suitable for simultaneous determination of subnanogram per gram of Ru, Pd, Re, Os, Ir, and Pt and Os isotope analysis in geological, mineralogical, and environmental samples without direct addition of toxic reagents required in distillation/extraction of Os or oxidizing of Ir.     

Thermal Properties of Polyacrylates at Metal Interfaces

Summary  The thermal properties of polyacrylates films sandwiched with metal were studied by differential scanning calorimetry. There were two glass transition relaxations, and the relaxation at the lower temperature, which was almost the same as the glass transition temperature of a bulk sample, diminished with thinning the polymer film. The glass transition relaxations at the higher temperature can be explained by the segmental motion of polymer chains interacting with metal surfaces at the interface. The results for the dielectric measurements for the sandwiched films also showed the similar relaxation modes.     

有机半导体薄膜三极管的研制

采用真空蒸镀法和有机半导体材料酞菁铜,制作Au/CuPc/Al/ CuPc/Au三明治结构的肖特基型栅极有机静电感应三极管.该三极管导电沟道垂直于CuPc薄膜,与采用MOSFET结构的有机薄膜三极管相比导电沟道大幅缩短,有利于克服有机半导体电学性能的缺点.实验结果表明,该三极管驱动电压低,呈不饱和电流-电压特性.其工作特性依赖于栅极电压和梳状铝电极的结构.通过合理设计、制作梳状铝电极,获得了良好的三极管静态、动态特性.