GTO DC Circuit Breaker Based on a Single-Chip Microcomputer

A single-chip microcomputer is used to obtain a versatile GTO circuit breaker for electric railway substations. The microcomputer provides firing control, excellent dc short-circuit fault interrupting performance, precise overload protection of circuit breakers by themselves, as well as high reliability with minimum components. Emphasis is on the GTO junction temperature observation.     

Infrared spectroscopic analysis of OH− and OD− in crystalline Li2O as a function of chemical treatment

Infrared spectroscopy has been used to study the chemical form and approximate concentration of OH^? and OD^? in Li₂O single crystals as a function of chemical treatment. Infrared absorption maxima at $\text{(3671±0.5)}\text{cm}{}^{\mathrm{?1}}\text{and}\text{(2711±3.3)}\text{cm}{}^{\mathrm{?1}}$ were observed for OH^? and OD^?, respectively. The absorption coefficient for OD^? was determined to be $\text{4.0±0.4}$ absorbance units per mol part per million OD^? per mm of sample thickness. Vacuum baking of Li₂O crystals reduced the OH^? and OD^? concentrations to <50 mppm; baking in a low moisture-level D₂ environment at 600 to 800°C appeared to lead to volatilization of LiD from the Li₂O crystals; and baking in D₂ containing ($\text{350±50}$) mppm D₂O at 600 to 800°C produced a measurable quantity of LiOD. In all cases, the observed spectra indicated the presence of only one distinguishable form of OH^? or OD^? in the Li₂O lattice. Because of the close correspondence of the observed absorption maxima to reported values for pure LiOH and LiOD, the most consistent (although not conclusive) interpretation is that the OH^? and OD^? are present as a separate LiOH or LiOD phase at room temperature. Only limited conclusions can be drawn regarding the chemical state of OH^? and OD^? during the elevated temperatures exposures. An estimate of the approximate value for the solubility of tritium in Li₂O at 800°C was made using data from D₂/Li₂O isothermal exposure experiments — this value was ? 25 wppm.     

He+ ion energy loss parameter in thin films of UO2

The stopping cross sections of He⁺ ions in vacuum evaporated films of UO₂ have been measured at incident energies from 0.3 to 2.0 MeV. A procedure has been described for obtaining true stopping cross sections by using thin films having various thicknesses. The energy loss parameter of He⁺ ions was determined using slopes at the origin in relative energy loss vs. thickness curves.     

Investigation of cobalt buildup behavior and suppression by zinc injection on stainless steel under HWC conditions using simultaneous continuous measurements of corrosion and cobalt buildup

In boiling water reactor (BWR) plants, cobalt-60 (⁶⁰Co) is the main source of radiation exposure, and it builds up on oxide films of structural materials. The ⁶⁰Co buildup is caused by its incorporation into the oxide films. In the BWR plants using hydrogen water chemistry (HWC) to mitigate the oxidative environment, Zn injection has been applied to reduce the ⁶⁰Co incorporation. In this work, we studied the incorporation mechanism of ⁶⁰Co into the oxide films on type 316 stainless steel and the suppression mechanism of ⁶⁰Co incorporation. In order to discriminate between coprecipitation and adsorption of ⁶⁰Co incorporation under HWC conditions, we measured the corrosion amount of the base metal and the ⁶⁰Co buildup amount, using simultaneous continuous measurements for 500 h. The ⁶⁰Co incorporation increased with time both with and without Zn injections. We found that the time dependencies of ⁶⁰Co incorporation with and without Zn have one and two regions, respectively. In the initial stage for both, ⁶⁰Co was incorporated mainly by coprecipitation. After 100 h without Zn, ⁶⁰Co was incorporated by both coprecipitation and adsorption. These results mean that Zn suppressed both coprecipitation and adsorption of ⁶⁰Co.     

Irradiation effects on thermal diffusivity and positron annihilation lifetime in ceramics induced by neutron and 30 MeV electron

Measurements of thermal diffusivity and positron annihilation lifetime were performed on neutron- and 30 MeV electron-irradiated ceramics. Thermal diffusivity of heavily neutron-irradiated ceramics decreased to a very low level and the difference between specimens was small. Positron annihilation lifetime of these specimens also showed a distinct change; however, the difference between specimens was also small. Accordingly, in this study, electron irradiation was performed to 0.01–0.02 dpa via the 30 MeV KURRI-Linac. The electron-irradiated specimens also showed obvious degradation in thermal diffusivity and an increment in positron annihilation lifetime, and it was clarified that positron annihilation lifetime showed some correlation with thermal diffusivity.     

A Rapid and Simple Method for the Determination of 2-Alkylcyclobutanones in Irradiated Meat and Processed Foods

A rapid and simple method has been developed for the determination of 2-alkylcyclobutanone, 2-dodecylcyclobutanone (DCB), and 2-tetradecylcyclobutanone (TCB) in irradiated meat and processed foods. The procedure consists of extraction with n-hexane, following defatting and cleanup with a silica gel mini-column before gas chromatograph–mass spectrometry analysis. The method was evaluated using samples of beef, pork, Parmesan cheese, fried chicken, hamburger, gyoza (Chinese dumplings), and gyudon (boiled beef and onion seasoned with soy sauce and sugar). The recoveries of spiked DCB were 67–88 %, and those of TCB were 70–86 %. Furthermore, the method could detect DCB and TCB from samples irradiated at 1.0 and 2.6 kGy at levels dependent on dose; DCB and TCB were not detected in any nonirradiated samples. The method did not require special equipment, such as Soxhlet extraction, accelerated solvent extraction, or supercritical fluid extraction, for sample preparation. Thus, this method would be useful for determining DCB and TCB levels in irradiated meat and processed foods.     

Electrochemical polymerization of aniline in the presence of poly(acrylic acid) and characterization of the resulting films

Conducting films composed of polyaniline (PANI) and poly(acrylic acid) (PAA) were prepared by electrochemical polymerization of aniline in the presence of PAA. The PAA content in the films (PANI/PAA films) was controlled by the concentration of PAA in polymerization solution, and the properties of the films were investigated in relation to the PAA content. It was demonstrated by means of scanning electron microscopy and cyclic voltammetry that the surface morphology and electrochemical property of the films were affected significantly by the PAA content. In contrast, the conductivity of the films was found hardly dependent on the PAA content up to 18 wt %. The cyclic voltammetry gave an interesting result that the PANI/PAA films showed an electroactivity in neutral solution, which was not observed for the PANI film without PAA, and the electroactivity was closely related to the PAA content in the PANI/PAA films.     

Determination of <Emphasis Type="SmallCaps">d</Emphasis>,<Emphasis Type="SmallCaps">l</Emphasis>-Amino Acids in Collagen from Pig and Cod Skins by UPLC Using Pre-column Fluorescent Derivatization

A simple and sensitive analytical method for the quantification of d,l-amino acids by ultra-performance liquid chromatography (UPLC) with fluorescence (FL) detection is described. The reaction of the R(-)-4-(3-isothiocyanatopyrrolidin-1-yl)-7-(N,N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole [R(-)-DBD-PyNCS] with d,l-hydroxyproline (Hyp), glycine (Gly), d,l-aspartic acid (Asp), and d,l-proline (Pro) effectively proceeds at 55 °C for 20 min in the presence of 3% TEA to produce the corresponding fluorescent diastereomers (excitation at 460 nm, emission at 550 nm). The mixture was simultaneously separated within 20 min on an ACQUITY UPLCTM BEH C18 (1.7 μm, 100 mm?×?2.1 mm i.d.) by gradient elutions using water–acetonitrile containing 0.2% formic acid as the mobile phase. Peak resolution was in the range of 1.62 (d,l-Asp), 2.99 (d,l-Pro), and 6.74 (d,l-Hyp). A good linearity was achieved from the calibration curves (r²?>?0.9984) in the range of 1.0~100 pmol; the limit of detection (S/N?=?3) was 42.0–250 fmol, the inter-day and intra-day assay precisions were all less than 6.23%, and the mean recoveries (%) of the d,l-amino acids spiked in the collagen from pig and dried cod skins were 87.58–107.41%. The derivatives of the free d,l-amino acids in the collagen were successfully identified by the proposed procedure. To the best of our knowledge, for the first time, these three kinds of d-amino acids, which were d-Asp, d-Pro, and d-Hyp, were detected in the collagen samples.     

Methods for controlling airflow in and around a building under cross-ventilation to improve indoor thermal comfort

This paper investigates methods for controlling airflow in and around a building in order to improve indoor thermal comfort by utilizing cross-ventilation. In the first part of the study, field measurements are carried out to evaluate the effects of cross-ventilation on indoor thermal comfort. It was confirmed that a comfortable indoor thermal environment could be attained in a considerable part over summer by controlling the window opening in order to maintain the PMV value within the range −0.5<PMV<+0.5. The latter part reports on CFD predictions of flow in and around a building. The effects of planted tree arrangements around the building, openings locations and size of openings in the building are numerically investigated.