Analysis of the self-excited three-phase synchronous generator utilizing the second space harmonic for excitation

In a previous paper, we proposed a new self-excited three-phase synchronous generator in which the second space harmonic component of the armature reaction field is used for exciting the field system, and clarified its operating principles and basic characteristics by experiment. The new generator has a series excitation characteristic, and responds quickly to a sudden change of load, because an excitation power can be directly obtained from the armature reaction field. This paper introduces a method for analyzing the steady-state performance of our new generator. In the analysis, an equivalent circuit of the generator is derived from a duality between interlinked electric and magnetic circuits. A simple determination method of parameters in the equivalent circuit is also shown. Calculated results are compared with the experimentally obtained values on a laboratory machine, and good agreement between both values has been observed. The proposed analysis is useful for simulating the steady-state performance of the generator by taking into account the nonlinear effect of the iron core due to magnetic saturation. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 121(1): 70–81, 1997     

Growth of Polarity-Controlled ZnO Films on (0001) Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

The polarity control of ZnO films grown on (0001) Al₂O₃ substrates by plasma-assisted molecular-beam epitaxy (P-MBE) was achieved by using a novel CrN buffer layer. Zn-polar ZnO films were obtained by using a Zn-terminated CrN buffer layer, while O-polar ZnO films were achieved by using a Cr₂O₃ layer formed by O-plasma exposure of a CrN layer. The mechanism of polarity control was proposed. Optical and structural quality of ZnO films was characterized by high-resolution X-ray diffraction and photoluminescence (PL) spectroscopy. Low-temperature PL spectra of Zn-polar and O-polar samples show dominant bound exciton (I₈) and strong free exciton emissions. Finally, one-dimensional periodic structures consisting of Zn-polar and O-polar ZnO films were simultaneously grown on the same substrate. The periodic inversion of polarity was confirmed in terms of growth rate, surface morphology, and piezo response microscopy (PRM) measurement.     

Successful treatment of dark-colored epidermal nevus with ruby laser

The pulsed ruby laser has a selective thermolytic effect. Recently, it has been available for the treatment of superficial pigmented disorders. We studied 5 cases of epidermal nevus treated with the pulsed ruby laser. In comparison with the usual methods including electrocautery, cryotherapy and skin abrasion, ruby laser therapy is an excellent tool due to technological ease and rapid improvement. Depigmentation after treatment in 2 cases was the only side effect of this therapy. Bose cases had a dark pigmentation of the skin. Despite of the risk of discoloration, the ruby laser is one of the most effective tools for therapy of pigmented epidermal nevus.     

Functional analysis of CD82 in the early phase of T cell activation: roles in cell adhesion and signal transduction

To define T cell co-stimulatory molecules that work in the early phase of T cell activation, we established monoclonal antibodies (mAb) that inhibit or enhance T cell activation by the histiocytic leukemia cell line U937. One of the mAb, 53H5, which recognized both T cells and U937, was identified to bind to CD82 by expression cloning. Functional analyses of CD82 revealed that 1) CD82 needs to exist on both T cells and U937 for the full activation of T cells; 2) CD82 expression is up-regulated on both T cells and U937 by stimulation such as CD3 ligation or treatment with phorbol 12-myristate 13-acetate; 3) overexpression of CD82 enhances both homotypic and heterotypic cell adhesion between T cells and U937; 4) CD82 signal co-stimulates T cells and the signal works synergistically with the CD28-mediated T cell co-stimulation signal; 5) in mixed leukocyte reactions using U937 as stimulator cells, CD82 overexpression on U937 correlates with the higher allogeneicity of U937 cells. These results indicate that CD82 co-stimulates T cells not only by sending intra-T cell signals that work synergistically with CD28 signals but also by inducing enhanced T cell-antigen-presenting cell interaction.     

Electrical conduction properties of Sr-doped Bi<Subscript>4</Subscript>(SiO<Subscript>4</Subscript>)<Subscript>3</Subscript> with the eulytite-type structure

Electrical conduction in 1 mol% Sr-doped Bi₄(SiO₄)₃ with the eulytite-type structure at elevated temperatures was investigated with conductivity measurements. Conductivity of the material under wet condition was higher than that under dry condition, and were 1.2 × 10⁻⁶ – 9.7 × 10⁻⁵ S cm⁻¹ at 500–850 ^°C. From H/D isotope effects and p(O₂)-dependencies of the conductivity, it was found that the Sr-doped Bi₄(SiO₄)₃ exhibited protonic conduction at all the temperatures investigated while contribution of p-type conduction became significant with increasing p(O₂) and/or temperature. Protonic and p-type conductions in the material were discussed in terms of defect equilibria.     

Mechanical properties of As-cast and directionally solidified Nb-Mo-W-Ti-Si <Emphasis Type="Italic">in-situ</Emphasis> composites at high temperatures

To improve the high-temperature strength of Nb-Mo-Ti-Si in-situ composites, alloying with W and a directional solidification technique were employed. The alloy composition of Nb-xMo-10Ti-18Si (x=10 or 20) was used as the base, and Nb was further replaced by 0, 5, 10 and 15 mol pct W. For samples without W, the as-cast microstructure was a eutectic mixture of fine Nb solid solution (Nb _SS ) and (Nb, Me)₅ Si₃ silicide (Me = Mo, W, or Ti), while large primary Nb _SS particles appeared besides the eutectic mixture as a result of replacing Nb by W. The directionally solidified samples consisted of coarse Nb _SS and (Nb,Me)₅ Si₃ silicides, and the microstructure showed a slight orientation in the direction of growth. The maximum compressive ductility (ɛ _max) at room temperature decreased with increasing W content and was in the range of 0.8 to 2.3 pct, in contrast to the Vickers hardness (HV), which increased with W content. The 0.2 pct yield compressive strength (σ _0.2) and the specific 0.2 pct yield compressive strength (σ _0.2S ) (σ _0.2 divided by the density of sample) at elevated temperatures were markedly improved by the W addition. The directionally solidified samples always showed higher σ _0.2 and σ _0.2S values than the as-cast samples. At elevated temperatures, the directionally solidified sample with 10 mol pct Mo and 15 mol pct W had the highest σ _0.2 and σ _0.2S values; even at 1770 K, σ _0.2 was as high as 650 MPa. The directionally solidified materials alloyed with W exhibited excellent compressive creep performance. The sample with 10 mol pct Mo and 15 mol pct W had a minimum creep rate of 1.4×10⁻⁷s⁻¹ and retained steady creep deformation at 1670 K and an initial stress of 200 MPa. Under compression, the damage and failure of these in-situ composites were dominated by decohesion of interfaces between the Nb _SS and silicide matrix.     

Pleural malignant mesothelioma with osseous cartilaginous and rhabdomyogenic differentiation

A 63-year-old man, who was formerly an asbestos factory worker who had been followed due to asbestosis, and was admitted to our hospital with left chest pain and dyspnea on exertion. A chest X-ray and chest computed tomogram (CT) on admission revealed a large tumor in the left lung field. Percutaneous needle biopsy determined that the tumor was a sarcoma. No clinical response was obtained by systemic chemotherapy. The autopsy revealed diffuse malignant mesothelioma of sarcomatous type with osseous, cartilaginous and rhabdomyogenic differentiation. Osseous and cartilaginous differentiation in a malignant mesothelioma is rare, and the presence of a malignant rhabdomyogenic component is the first to be described in the Japanese literature.     

Application of nano-diffraction to local atomic distribution function analysis of amorphous materials

A method is proposed for the local atomic distribution function analysis of amorphous materials. This method is based on local halo-electron diffraction intensity analysis with nano-sized electron probes as small as 25 to approximately 3 nm, taking advantage of the intensity recording with imaging plate. Nanodiffraction and selected area electron diffraction (SAED) patterns from an amorphous SiNx (x approximately 4/3) thin film were taken using a conventional transmission electron microscope operated at 200 kV and recorded on imaging plates. An intensity correction to omit inelastic intensity was made using electron energy-loss spectroscopy. When a beam-convergence angle is larger than 1 x 10(-3) rad, the Wiener-filter deconvolution method becomes helpful in producing atomic pair distribution functions (PDFs) from the nano-diffraction intensity profiles that are more similar to the PDF from the SAED intensity. This technique was applied to the analysis of local amorphous structures of SiO2 layers formed by an oxygen-ion implantation into single crystal SiC.     

Power balance investigation in steady-state LHCD discharges on TRIAM-1M

A discharge longer than 5 h was successfully achieved on TRIAM-1M by fully non-inductive lower hybrid current drive (LHCD). The heat load distribution into the plasma facing components (PFCs) during the 5 h discharge was investigated using calorimetric measurements, which estimated that the injected radio frequency (RF) power coincided with the total heat load amount to the PFCs. The power balance, including the portion of direct loss power of the fast electrons and the heat flux due to the charge exchange (CX) process, was also investigated.