Wind-flow measurement over the Subaru Telescope

Wind flows over the 8.2-m Subaru Telescope at Mauna Kea in Hawaii were analyzed with a correlation method. Three or four wind flows were detected from our measurements. Spatial and temporal resolution of the wind-flow analysis across the 8.2 m pupil were investigated experimentally. A three-dimensional spatiotemporal-frequency analysis was also applied to the wind-flow data.     

Magnetization Curve of Two-Dimensional Anti-ferromagnetic Solid 3He on Graphite

Two-dimensional anti-ferromagnetic solid ³He on graphite, so called 4/7 phase, is a highly frustrated magnetic system and its ground state is considered to be a gapless spin liquid. Then how is the behavior in high magnetic fields? We tried to observe the magnetization curve at around 1 mK in high magnetic fields up to 10 T, using a Faraday-type magnetometer. To eliminate a large background signal from graphite as a substrate and copper as a thermal link, a double gradient coil system is employed to produce opposite field gradients in two regions equidistant from the field center. Preliminary results of the 4/7 phase on graphite show no saturated magnetization even at 1 mK and 10 T, suggesting the existence of magnetization plateau.     

Analytic Flow Design Method for an Automated Distribution Center with Multiple Shipping Areas

An analytic flow design algorithm for an automated distribution center with multiple shipping areas is presented. The main elements of the analytic flow design are the number of devices and the volumes of product flow between the devices. In the design of an automated distribution center, it is necessary to satisfy the demand throughput while minimizing construction costs. In the conventional design process, system engineers utilize experimental and intuitional approaches. However, conventional approaches are time-consuming and the design outcome is dependent on the skill of the designer. Therefore, a theoretical design algorithm is needed. We propose an analytic flow design algorithm using a dynamic network flow model and considering time-variable flow volumes according to shipment and storage schedules. To verify the feasibility of the proposed method, we perform analytic flow design using real data and confirm that the proposed method can yield a feasible analytic flow design in several minutes.     

Organic LED full-color passive-matrix display

Abstract— A full-color 5.2-inch 1/4-VGA passive-matrix organic LED display has been developed, adopting selective deposition for the different emitting materials. The display features 320 (×3) × 240 pixels with an equivalent pixel size of 0.33 × 0.33 mm, white peak luminance of over 150 cd/m², and power consumption of 6 W.     

High-Performance Control Strategy of Cycloconverter-Fed Induction Motor Drive System Based on Digital Control Theory

The field-oriented control, or the vector control, has emerged as a powerful tool for controlling squirrel-cage induction motors. The dynamic performance, however, depends on the controllability of the stator currents.     

Preparation of SrBi 2 Ta 2 O 9 Thin Films by Liquid-Delivery MOCVD Without Additional Solvents

SrBi 2 Ta 2 O 9 thin films were prepared by ECR plasma enhanced metalorganic chemical vapor deposition (ECR-MOCVD) with a liquid-delivery system using one cocktail source without an additional solvent. The strontium-tantalum double alkoxide, Sr{Ta[OC 2 H 4 H(CH 3 ) 2 ](OC 2 H 5 ) 5 } 2 , was dissolved in stabilized trimethyl bismuth, Bi(CH 3 ) 3 / dioxane. This source system has been used in a conventional bubbling system. Deposition rate and the composition of the films were strictly controlled by the concentration and the composition of the cocktail source. Therefore, high reproducibility was realized by using this system. The constituent phase of the stoichiometric SBT film as-deposited at 500 C on a (111)Pt/TiO 2 /SiO 2 /Si substrate was a fluorite phase and transformed to the single phase of SBT by the post annealing at 800 C. It showed almost the same ferroelectricity as the stoichiometric composition film.     

Experimental verification of a dynamic voltage restorer capable of significantly reducing energy‐storage element requirements

This paper deals with a dynamic voltage restorer (DVR) characterized by installing the shunt converter at the load side. The DVR can compensate for the load voltage when a voltage sag appears in the supply voltage. An existing DVR requires a large capacitor bank or other energy‐storage elements such as double‐layer capacitors or batteries. The DVR presented in this paper requires only a small DC capacitor intended for smoothing the DC‐link voltage. Moreover, three control methods for the series converter are compared and discussed to reduce the series‐converter rating, paying attention to the zero‐sequence voltages included in the supply voltage and the compensating voltage. Experimental results obtained from a 200‐V, 5‐kW laboratory system are shown to verify the viability of the system configuration and the control methods. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(3): 73–82, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20460     

Modified thermoelectric figure of merit estimated from enhanced mobility of [100] oriented beta-FeSi<Subscript>2</Subscript> thin film

The modification of thermoelectric figure of merit was estimated from enhanced mobility of [100] oriented beta-FeSi₂ film. beta-FeSi₂ on Si(001) substrate was prepared by molecular beam epitaxy method using an Fe source. The crystallographic orientation of beta-FeSi₂ film on Si(001) substrate was characterized by using X-ray diffraction. Using scanning electron microscopy, surface morphology and film thickness of samples were observed and estimated, respectively. The mobility of beta-FeS₂ film on Si(001) substrate were also characterized by Hall measurement at room temperature. A part of the enhancement of figure of merit was evaluated as the functions of mobility and crystallographic orientation of samples.     

A bidirectional isolated DC/DC converter as a core circuit for 3.3‐kV/6.6‐kV power conversion systems in the next generation

This paper describes a bidirectional isolated DC/DC converter considered as a core circuit for next‐generation 3.3‐kV/6.6‐kV high‐power‐density power conversion systems. The DC/DC converter is intended to use power switching devices based on SiC and/or GaN, which will be available on the market in the near future. A 350‐V, 10‐kW, and 20‐kHz DC/DC converter is designed, constructed, and tested in this paper. It consists of two single‐phase full‐bridge converters with the latest trench‐gate Si‐IGBTs and a 20‐kHz transformer with a nano‐crystalline soft‐magnetic material core and litz wires. The transformer plays an essential role in achieving galvanic isolation between the two full‐bridge converters. The overall efficiency from the DC‐input to DC‐output terminals is accurately measured to be as high as 97%, excluding gate drive circuit and control circuit losses from the whole loss. Moreover, loss analysis is carried out to estimate effectiveness in using SiC‐based power switching devices. The loss analysis clarifies that the use of SiC‐based power devices may bring a significant reduction in conducting and switching losses to the DC/DC converter. As a result, the overall efficiency may reach 99% or higher. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(2): 75–83, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20505     

日本彩色聚乙烯涂覆钢管的开发

试验了彩色聚乙烯涂覆钢管的耐腐蚀性和耐气候性，由于聚乙烯涂层隔绝水的作用，聚乙烯涂覆钢管具有优良的耐腐蚀性能，电阻绝缘值和优良的机械性能。建立了一个新的方式去研究分析聚乙烯抗老化剂消耗和在聚乙烯中的扩散。用有效测定的方法定量地预测彩色聚乙烯涂覆层的寿命，应用这些分析结果，不仅可使新的有色聚乙烯涂覆钢管在恶劣腐蚀环境介质情况下具有高的耐腐蚀性，而且有长的耐气候性。