A new method for estimating initial rotor phase of self‐excited hybrid‐field synchronous motors

This paper proposes a new method for properly estimating the rotor initial phase (i.e., the position) of the newly emerging self‐excited hybrid‐field synchronous motors (SelE‐HFSMs), which have the rotor held by both a permanent magnet and a diode‐shorted held winding. The proposed method injects a spatially rotating high‐frequency voltage and detects the rotor phase directly by evaluating the norm of the associated current. The method is very simple, but has a high degree of usability. 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(3): 49–58, 2010; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.21027     

Connection structures between type-I and type-II defects in neutron irradiated beta-Si3N4

High-resolution electron microscopy (HREM) observation clarified that various types of interstitial dislocations were induced into beta-Si3N4 by high-dose neutron irradiation, and two of them have been analysed and reported in our previous papers. These two defective structures are called type-I and type-II. They are interstitial dislocation loops introduced into [100] and [110] planes, respectively. In this study, it was found that some of these dislocation loops connected with each other. The connections of type-I-L2-type-II-B and type-I-R2-type-II-A dislocations were observed by HREM. Tetrahedral arrangements of the connected parts are proposed, based on the simplified crystal structure model of beta-Si3N4. In addition, a new type of defect, type-III, was found. Type-III is an interstitial dislocation loop introduced into [100] planes. It was also found that type-I-A and type-III dislocations connected with each other.     

High-frequency characteristics of low-temperaturepseudo-heterojunction bipolar transistors

The high-frequency characteristics of a pseudojunction bipolar transistor (pseudo-HBT), which operates like an HBT despite a metallurgical homojunction utilizing a bandgap narrowing effect, are analyzed both theoretically and experimentally. Several design features used to achieve a high cutoff frequency at low temperatures are discussed. They include (1) a low-impurity-concentration graft base, (2) an abrupt base profile to obtain a large effective-bandgap difference between the base and the emitter, and (3) an inversely graded base profile, in which the impurity concentration increases from the emitter side to the collector side, to effectively reduce the base transit time. The pseudo-HBT with a low-concentration graft base shows a higher cutoff frequency below 100 K than at room temperature. These features are also appropriate for conventional bipolar transistors operating at low temperatures     

Tensile strained QW structure for low-threshold operation of short-wavelength, AlGaInP LDs emitting in the 630 nm band

The amount of tensile strain introduced into QWs and the optimum QW structure are evaluated for low-threshold operation of AlGaInP LDs in the wavelength range 630-640 nm. Very low threshold current of 32 mA under CW operation at 20 degrees C is achieved in an index-guided SQW LD emitting at 632 nm.<>     

Technology choice and CDM projects in China: case study of a small steel company in Shandong Province

Corporate motives and strategies of both investing and hosting country affect the outcomes of a clean development mechanism (CDM) project—who introduces what technology to whom—and result in large differences in economic viability and the CO₂ emission reductions. This is particularly true for steel industry in which steel making consists of many detailed and complex processes, a given strategy could produce cumulative effects of the individual technologies used, leading to large energy savings overall. The objective of this study is to demonstrate some analytical methods that can be used to quantitatively evaluate the impacts of technology selection on the profit performance of CDM projects. Specifically, in this study we analyze a CDM project to introduce energy saving technology from Japan to a small steel manufacturer in China's Shandong Province, and conduct a simulation of the quantitative relationships between various technology options and profitability. Based on these results, we examine the environmental and economic significance of technology selection for CDM projects. To take this further, we then reconsider the profitability of a project as typical FDI activity (i.e., without the CDM), and by comparing this outcome with the CDM case, we clarify the significance and potential of the CDM.     

Reduction in microalbuminuria in diabetics by eicosapentaenoic acid ethyl ester

Eicosapentaenoic acid (EPA) ethyl ester (1.8 g/d) was administered to 16 diabetic patients (5 insulin-dependent and 11 noninsulin-dependent diabetics) for 6 mon. EPA in total plasma fatty acids increased from 4.0±2.4 mol% (mean±SD) to 7.5±3.1 mol% (p<0.001). Albumin excretion, measured with spot urine, was significantly reduced from 65 to 36 mg/g creatinine (geometric means, p<0.001). Fasting blood sugar levels, glycohemoglobin, body weight and blood pressure did not change significantly during the study. There were also no significant changes in serum levels of creatinine, urea nitrogen, total cholesterol and triglycerides. Although no overt hemorrhage was observed in the patients, hematocrit was reduced from 42.6±2.8% to 41.0±3.9% (p<0.02). Ten other similar diabetic patients (4 insulin-dependent and 6 non-insulin-dependent diabetics) were followed as a reference group, not concomitantly, for 6 mon with neither EPA ethyl ester nor placebo. The parameters mentioned above were not changed significantly in this group during 6 mon. EPA administration might retard the appearance of overt diabetic nephropathy.     

Effects of External Stress on Defect Annihilation and Bubble Swelling During Annealing of Neutron-Irradiated Silicon Carbide

Silicon carbide ceramics fabricated by three different methods were neutron-irradiated in the Japan Materials Testing Reactor and were subsequently annealed free from stresses or under compressive external stresses. The macroscopic length monotonically decreased with annealing above the irradiation temperature, when annealing was performed below ∼1300°C. This decrease was not affected by the external stresses. However, annealing above ∼1300°C led to an increase in length in B-containing SiC. The expansion was caused by the formation and growth of He bubbles at grain boundaries. The growth occurred by flow of vacancies into bubbles. The compressive stress retarded the expansion along the loading direction. This retardation was compensated by a length incrase along the lateral direction. The effect of external stresses was discussed by considering differently oriented He bubbles. One bubble was stress favored and the other stress unfavored. The stress determined the diffusional flow of vacancy-He atom complexes between the favored and unfavored bubbles which were caused by anisotropic expansion under a directional stress.     

Multichannel fiber ferrule for a stable laser-diode array module

We developed a multichannel fiber ferrule for a stable laser-diode array module. To apply YAG laser welding to parallel butt couple between the laser-diode and the single-mode fiber arrays, hermetically sealed and precisely aligned equi-interval fibers are required. We describe a V-grooved ceramic ferrule for embedding fibers. Fibers are fixed by soldering, using a flat ceramic lid and aligned with a 250 μm pitch. Our ferrule allowed a metallic, stem mounting laser-diode, to be fixed by YAG laser welding. All 30 samples tested have a leak rate of less than 1×10^-10 atm·cc/s. Optical coupling of fabricated modules was 9.7±0.2 dB and coupling loss change from 25°C to 115°C was within 0.5 dB     

Nanoimprinting using release-agent-coated resins

A fluorinated self-assembled monolayer (F-SAM) is mainly used as the antisticking layer. To prevent the F-SAM coated on the nanoimprint lithography (NIL) mold from deteriorating, we propose a new form of nanoimprinting using a release-agent-coated resin. The results from measuring the surface free energy and observations by scanning probe microscopy (SPM) confirmed that the surface free energy, frictional force, and adhesion force of the release-agent spray-coated polymethylmethacrylate (PMMA) were lower than those of PMMA. To prove the release-agent spray-coated PMMA had a releasing effect, we tried to undertake thermal nanoimprinting on it using a mold without F-SAM. The pattern was clearly imprinted on the resin without any signs of adhesion.