Diagnostic methods for GIS-insulated switchgear insulation using external antenna

A partial discharge detection system was developed using an external antenna that can be easily installed on the outside of the GIS. The antenna is fitted closely to the outer circumference of the insulation spacer, and it can detect electromagnetic radiation of the partial discharge with high sensitivity. To have high sensitivity even in noisy condition, three kinds of methods that can eliminate external noise effectively were verified. In addition, the locating method of defect based on distance attenuation was confirmed. Actually, the insulation monitoring system which employs the antenna is used in a substation that had already been installed. At present, it is operating satisfactorily.     

Application of poly(vinyl alcohol) with an alkyl end group containing anionic groups to coal–water slurry as a dispersant

Anionic groups were introduced with copolymerization of corresponding vinyl monomers with vinyl acetate into poly(vinyl alcohol) (PVA) with an alkylthio end group. The polymers were investigated as a dispersant for coal-water slurry (CWM). Anionic groups such as sodium sulfonate and sodium carboxylate enhance remarkably the ability of PVA with an alkylthio end group to disperse coal. Sodium polyacrylic acid with an alkyl end group also showed a good ability of dispersing coal. The order of the ability of dispersing coal in these polymeric dispersants along with sodium napthalene sulfonate formaldehyde condensate (NSF) varied by the kind of coal used. In cases of the polymeric dispersants, the fluidity of coal in terms of dependence of viscosity on shear rate also varied, from dilatency to thixotropy, in accordance with coal used. Impurities in coal as well as surface properties of coal particles might play important roles in the properties of CWM. © 1995 John Wiley & Sons, Inc.     

IR tag detection and tracking with omnidirectional camera using track-before-detect particle filter

Robust user detection and tracking is one of the key issues for a personal robot to follow the target person. In this paper, a novel tracking system using an omnidirectional camera and IR LED tags is proposed. The users wear the tags on their ankles, and the tags emit a light pattern as its ID. The camera on the robot is used to detect and track their positions individually. A novel approach based on a track-before-detect particle filter is proposed. It detects and tracks the tags simultaneously, even if the tags are not synchronized with the camera sampling or are not fully observable. The effectiveness of the proposed system is evaluated by experiments using a prototype personal robot.     

Effect of sodium on repair weldability of SUS316FR for a fast breeder reactor

The effect of sodium on repair weldability of SUS316FR steel under the remaining sodium environment was investigated by transverse-Varestraint and laser cladding tests. Solidification brittle temperature range (BTR) of SUS316FR steel with AF solidification mode was 37 K. However, BTR was expanded from 37 to 67 K, as the amount of surface-adhered sodium increased from 0 to 7.99 mg/cm². From microstructural observation of the weld metal, there would be a possibility that metallic sodium existed at cell boundaries in the weld metal during welding solidification. According to the thermodynamic calculation, the sodium would expand the solid–liquid coexistence temperature range. It could be concluded that the enhanced solidification cracking susceptibility under the sodium environment would be attributed to the enlargement of the solid–liquid coexistence temperature range. Finally, it was confirmed that any solidification cracks and blowholes did not occur in the overlaid weld metal through multipass laser cladding tests. Namely, it could be confirmed that SUS316FR steel possessed superior repair weldability under the sodium environment.     

Discovery of unusual regional social activities using geo-tagged microblogs

The advent of microblogging services represented by Twitter evidently stirred a popular trend of personal update sharing from all over the world. Furthermore, the recent mobile device and wireless network technologies are greatly expanding the connectivity between people over the social networking sites. Regarding the shared buzzes over the sites as a crowd-sourced database reflecting a various kind of real-world events, we are able to conduct a variety of social analytics using the crowd power in much easier ways. In this paper, we propose a geo-social event detection method by finding out unusually crowded places based on the conception of social networking sites as a social event detector. In order to detect unusual statuses of a region, we previously construct geographical regularities deduced from geo-tagged microblogs. Especially, we utilize a large number of geo-tagged Twitter messages which are collected by means of our own tweets acquisition method in terms of geographic relevancy. By comparing to those regularities, we decide if there are any unusual events happening in monitoring geographical areas. Finally, we describe the experimental results to evaluate the proposed unusuality detection method on the basis of geographical regularities which are computed from a large number of real geo-tagged tweet dataset around Japan.     

Lubricating properties of TR Gel-lube—Influence of chemical structure and content of gel agent

Tribological properties of a new and unique thermo-reversible Gel-Lubricant (TR Gel-lube) have been investigated. TR Gel-lube that includes an amide-type gel agent in base fluid is repeatedly able to change from gel state to liquid state at the melting point of its gel agent. Very low friction coefficient is indicated because of adsorption on a metal surface, and the gel agent works as an oiliness agent. In this study, the correlation between the lubricating property and the gel agent's characteristics (chemical structure, content, etc.) was clarified. DSC tester was applied to evaluate the stability of the gel state by change of entropy and the thermodynamic consideration was examined. In addition, lubricating properties under practical conditions such as at high temperature and in the presence of water were proved.     

Synthesis and properties of poly(tetramethyl-1,6-silpyrenylenesiloxane) derivative with phenyl groups on pyrenylene moiety

Poly(tetramethyl-1,6-silpyrenylenesiloxane) derivative with phenyl groups on pyrenylene moieties (P1) was prepared via polycondensation of disilanol monomer, i.e. 1,6-bis(dimethylhydroxysilyl)-3,8-diphenylpyrene (M1). P1 exhibited the very high glass transition temperature (T _g) of 191 °C. The temperature at 5% weight loss (T _d5) of P1 was 482 °C, indicating the relatively good thermostability of P1. P1 exhibited the bathochromic effect in the absorption and fluorescence spectra, indicating the expansion of π-conjugation by introducing phenyl groups onto pyrene skeleton as well as the σ–π and σ*–π* conjugation between pyrene and silyl moieties. In addition, P1 exhibited relatively weak excimer emission because of the inhibition of the excimer formation of pyrene skeleton by introduction of bulky phenyl groups onto pyrene skeleton. The fluorescence quantum yields (Φ_Fs) of M1 and P1 in chloroform were determined to be 0.46 and 0.37, respectively. It was revealed that M1 and P1 exhibited the higher fluorescence intensity than 1,6-diphenylpyrene, owing to the effect of the introduction of silyl moieties onto pyrene skeleton.     

Monitoring of a calcination reaction of high reflective green-black (HRGB) pigments by using near-infrared electronic spectroscopy: calcination temperature-dependent crystal structural changes of their components and calibration of the extent of the reaction

This paper demonstrates the potential of near-infrared (NIR) electronic spectroscopy in nondestructive monitoring of a chemical reaction of inorganic functional material. For this purpose NIR spectra in the 12,000-4000 cm(-1) region were measured for high reflective green-black (HRGB) pigments (Co(0.5)Mg(0.5)Fe(0.5)Al(1.5)O(4)) calcined at 1000, 1100, and 1200 °C and pigments with the same components as HRGB but calcined at different temperatures (500-900 °C) (hereafter, called "Pigments A") . NIR spectra of their components such as Co(3)O(4), MgO, Fe(2)O(3), and Al(2)O(3) were also measured. The NIR spectra of Pigments A show two major broad bands. One arises from a (4)A(2)→(4)T(1) (T(h)) d-d transition of Co(II) in the 9000-6000 cm(-1) region. The other band in the 12,000-9000 cm(-1) region is assigned to a foot of the charge-transfer (CT) band of Fe(2)O(3). The Co(II) band contains three component bands that are characteristic of a spinel structure. A shoulder arising from (A(1-x)B(x))(Th)(A(x)B(2-x))(Oh)O(4) (A≡Co, Mg, B≡Fe, Al; inverse spinel structure) emerges near 5900 cm(-1) in the spectra of Pigments A calcined in the temperature range of 700-900 °C, indicating that the Pigments A calcined in this temperature range assume an inverse spinel structure. When the calcination temperature is above 1000 °C, the final product, HRGB, is produced. This is confirmed from the fact that HRGB shows peaks characteristic of a spinel structure that have different wavenumbers from those of the corresponding peaks of Pigments A. Wide-angle X-ray diffraction (WAXD) patterns were also measured for HRGB, Pigments A, and their components. Based on the NIR and WAXD data we investigated calcination-temperature-dependent crystal structural changes of the components. We also developed partial least squares (PLS) calibration models for the 9000-6000 cm(-1) region of the NIR spectra of HRGB and Pigments A. The score plot of latent variable (LV) 2 of the calibration model for calcination temperature demonstrates clearly the existence of an intermediate of the calcination reaction, which may be (A(1-x)B(x))(Th)(A(x)B(2-x))(Oh)O(4) (A≡Co, Mg, B≡Fe, Al).     

C32: Computations of Low-Energy Cages with Four-Membered Rings

C₃₂ cages built from four-, five-, six-, and seven-membered rings are computed. The computations are primarily performed with semiempirical quantum-chemical methods (AM1, PM3, SAM1), and altogether 199 cages are optimized. The energetics is further checked through ab initio HF SCF computations with the standard 3-21G basis set, and also by density functional theory at the B3LYP level in the standard 6-31G* basis set. All five levels of theory suggest a D_4d cage (two four-membered rings, eight pentagons, eight hexagons) as the lowest-energy structure. Temperature effects are treated in the terms of partition functions so that the entropy contributions are considered accordingly. The thermodynamic treatment points out five cages significantly populated at high temperatures. At very high temperatures the structure lowest in energy is not the most abundant isomer. There are just six conventional fullerenes C₃₂, built exclusively from pentagons and hexagons, however, only two of them show significant populations at high temperatures. The remaining three relatively stable cages contain at least one four-membered ring. No structure with a heptagon shows a non-negligible concentration at high temperatures. The study suggests that in the non-IPR region the quasi-fullerene cages with four-membered rings can in some cases be more important than the conventional fullerenes built from pentagons and hexagons only.