Detection of Damaged Distribution Surge Arresters Using an Impulse Generator

Distribution surge arresters with an internal series gap have been installed on Japanese distribution lines at high density to reduce lightning‐related overvoltages. In contrast, surge arresters are sometimes damaged by direct lightning strokes, particularly in winter. Measurement of the insulation resistance between the terminals of the surge arrester and measurement of the dc discharge voltage of the surge arrester are generally adopted to detect damaged arresters. However, if metal‐oxide (MO) varistors are damaged and the internal series gap is not damaged, it is difficult to detect damaged arresters by the two conventional methods. Therefore, this paper presents a proposed detection method that can accurately detect damaged arresters. In the proposed method, first, the voltage between the terminals of the surge arrester is measured when the output of an impulse generator is applied to the surge arrester. Second, the damaged arrester is detected by comparison between its voltage waveform and the voltage waveform of the nondamaged arrester. The detection rate of damaged arresters by the proposed method is markedly higher than the rates of detection by the two conventional methods.     

1,6-Anhydro-3,4-O-Fururylidene-β-D-Galactopyranose, A New Furfurylidene Derivative Formed from Lactose During Pyrolysis

A new fufurylidene derivative which tastes bitter was separated from lactose heated at 200°C for 20 hr by ethyl acetate extraction and preparative thin-layer chromatography. The compound was identified as the trans isomer of 1,6-anhydro-3,4-O-furfurylidene-β-D-galactopyranose by ultraviolet, infrared, mass and ¹H-NMR spectroscopy. The compound and its cis isomer were identified in the reaction mixture of furfural and levogalactosan heated at 175°C for 2 hr with nitric acid.     

Gel-Forming Characteristics and Rheological Properties of Kefiran

A water soluble polysaccharide “kefiran” produced by Lactobacillus kefiranofaciens was examined for its gel-forming and rheological properties. Kefiran (3%) formed gel in the presence of ethanol (4–10%). The gel strength in 8% ethanol was comparable to that of 3% gelatin gel in water. Addition of casein (3%) increased gel strength 1.5–2.0 fold. The unique properties of kefiran may make it a useful food additive.     

Computationally Efficient Large-Eddy Simulation of Periodic Unsteady Flow using Harmonic Balance Method

To improve the efficiency and fidelity of the numerical analysis for cascade flutter, we propose an efficient scale-resolving simulation method dedicated to time-periodic flows by incorporating the harmonic balance approach into the large-eddy simulation. This method combined convergence calculations of the steady-state problem based on the harmonic balance method for periodic components, and the nonlinear time-marching method for turbulent fluctuations. Using the proposed method, deterministic periodic components and stochastic turbulent fluctuations were calculated simultaneously, and the effect of turbulent fluctuations on deterministic periodic components was directly calculated without using turbulence models. In this paper, we explain the algorithm and feature of this simulation technique and present the results of the computation for channel flow excited in the streamwise direction as an analysis example using the proposed method. In order to validate the proposed method, an analysis of sinusoidally pulsating channel flow at the central friction-velocity Reynolds numbers Rer = 180 was conducted, confirming that the amplitude and phase of the mean velocity oscillation computed by the proposed method were in good agreement with those of the conventional LES. The present calculation achieved an order of magnitude improvement in computational efficiency compared to conventional LES.     

Dielectric Properties of Ceramics in the System (Sr0.50Pb0.25Ca0.25)TiO3-Bi2O3·3TiO2 and Their Applications in a High-Voltage Capacitor

The dielectric behavior of (1- x )(Sr_0.5Pb_0.25Ca_0.25) TiO₃-x(Bi₂O₃·3TiO₂) was studied using x=O to 8.25 mol%. Around the point at which x equals 1.56 mol%, the following phenomena were observed: (1) At −;22°C, the weak field permittivity increased substantially with a dc bias field, becoming more than twice the zero bias value at a field of 3 kV/mm; (2) the permittivity peak shifted markedly toward a high temperature under a dc bias field; (3) relaxation behavior was evident; and (4) there are large hysteresis loops at low temperatures and double hysteresis loops, which seem to be related to a field-enforced ferroelectric phase, in a wide temperature range. We used dielectrics with an optimized composition of x =4.30 mol% in a small, highly reliable, 15-kV high-voltage ceramic capacitor.     

Preparation and characterization of glass composite using metal particles coated with semiconductive SnO2 fine particles obtained via sol—gel method

SnO₂—glass composites are promising materials for nitrogen-fireable thick film resistor systems. However, the SnO₂—glass composite has many undesirable properties which should be improved for industrial application, such as a high electrical resistivity and a large negative temperature coefficient of electrical resistance. This work was undertaken to make a survey of the methods for improvement in the electrical properties of the SnO₂—glass composites. The effect of the addition of Cu particles, with a large positive temperature coefficient of electrical resistance, on the electrical properties of SnO₂—glass composites has been investigated. Cu particles have been coated with semiconductive SnO₂ fine particles by hydrolysing tin and antimony ethoxides then firing. The coated particles have been applied as conductive components in the glass composite. Using SnO₂-coated Cu particles, Cu and SnO₂ particles are homogeneously dispersed in a glass matrix, and the electrical properties of the glass composites largely depend on the volume fraction of Cu in the glass composite. The volume fraction of Cu in the glass composite is determined by a Cu/SnO₂ volume ratio in the coated particles. From the experimental evidence, it is thought feasible to produce the glass composite having well-controlled electrical properties by the suitable selection of the Cu/SnO₂ ratio in the coated particles. This revised version was published online in July 2006 with corrections to the Cover Date.     

ANALYSIS OF DIFFUSE PARENCHYMAL LIVER DISEASE BY LIVER SCINTIGRAMS: DIFFERENTIAL DIAGNOSIS USING FUZZY INFERENCE AND GENETIC ALGORITHM IN NUCLEAR MEDICINE

In nuclear medicine, diagnosis of diffuse parenchymal liver disease such as chronic hepatitis (CH) or liver cirrhosis (LC) is evaluated by size and distortion of the liver, distribution of radioactive tracer in the liver, size and activities of the tracer in the spleen, the degree of visualization of the bone marrow, etc. using colloid liver scintigraphy, It is not difficult to read a scintigram for a typical pattern; however in some cases it is difficult to distinguish between normal and CH or CH and LC visually. Therefore, we tried to use fuzzy inferences to perform differential diagnosis. Using fuzzy inference, differential diagnosis of LC could be performed up to 100%, but those of CH and Severe fibrosis (SF) could not be performed sufficiently. Therefore genetic algorithm was tried to determine the fuzzy rules. By combining genetic algorithm and fuzzy inference, CH, SF, and LC could be differentiated to the degree 70%, 60%, and 100%, respectively.     

Comparative Studies on the α and α-Phosvitin from Hen's Egg Yolk

Physico-chemical properties of α and β-phosvitin were compared. Considerable difference was observed in amino acid composition. Higher concentrations of carbohydrates were found in the β-component than in α. The α-phosvitin was more precipitable with lo-15 mM Ca ion than β. Phosvitin was so heat resistant that no change was observed on electropherogram by heating below 100°C for 10 min, and no coagulation occurred up to 140°C. About 12% of the phosphorus was liberated from whole phosvitin by heating at 140°C for 10 min. All preparations of phosvitin isolated from six individual eggs and mixed yolk of 57 eggs contained the two components.     

Evaporation of Zinc Oxide from Spinel Solid Solutions in Vacuum

The mechanism for the evaporation of ZnO from powders of (Zn₀₂Co_0.8)O·Al₂O₃ (ZCA) and (Zn_0.2Ni_0.8)O·Al₂O₃ (ZNA) spinels was studied at 1335° to 1500°C in vacuum of 3×10⁻⁵ to 10⁻⁴ torr. The evaporation of ZnO occurred in two stages: at a constant rate in the first and a decreasing rate in the second. The rate-determining process was analyzed as a decomposition reaction at the first stage and as the conjugated process of decomposition reaction and diffusion in the solid at the second. The evaporation rate constant and surface emissivity showed a similar dependence on temperature. The ratio of the concentration of ZnO at the surface to the initial concentration was =0.7 when the first stage of evaporation changed to the second.