Analysis of transient surge transmission characteristics of electronic circuits due to arc discharge generated with disconnector on/off in GIS

In gas‐insulated switchgear (GIS), the arc discharge due to a disconnector on/off generates fast transient surges, which can be the cause of malfunction and damage to electronic devices such as microprocessors and AD converters, if the fast transient surge exceeds a specified level. In this paper, it is shown that the comparison and evaluation are realized between the measured results and the calculated ones of fast transient surges generated due to a disconnector on/off in 300 kV GIS by adopting the evaluation index. The calculation is carried out by applying the authors' proposed equivalent circuits using distributed constant lines in consideration of the structure of GIS and a newly developed divided‐type voltage sensor. Also, it is found by using the evaluation index that the measured results and the calculated results are in good agreement with each other. Furthermore, the cause of the occurrence of the peak of the evaluation index is clarified by analyzing the equivalent circuit. And the signal conditioning using a low‐pass filter for electronics circuits connecting the divided‐type voltage sensor is designed. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(2): 34–42, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10360     

Preface

Journal of Materials Synthesis and Processing -     

Nonparametric preventive maintenance optimization models under earning rate criteria

The expected profit is frequently used as an optimality criterion in manufacturing and maintenance operations. In this paper, we consider the optimal preventive maintenance policy and the optimal repair limit policy which maximize the expected earning rates for one-unit systems subject to failure and repair, respectively. In particular, the total time on test concept is used to directly estimate the optimal policies from empirical sample data. The proposed methods provide geometrical interpretations of the underlying probabilistic problems to practitioners as well as nonparametric estimators of the optimal maintenance strategies.     

An international length comparison at an industrial level using a photoelectric incremental encoder as transfer standard

A Japanese–German interlaboratory comparison of length measurements was conducted. A photoelectric incremental encoder with a measurement length of 270 mm was used as transfer standard. An agreement of better than 27 nm over the entire length was ascertained, and the “short-range” deviations within a length interval of approximately 10 mm could be characterized with a standard deviation of σ=0.8 nm. The results attained are considered as consistent with the estimated uncertainties of measurement. Since the measurements performed are directly traceable to the SI unit of the “metre”, the comparison supports ideas currently being discussed by some National Metrology Institutes and dealing with the question of how foundations can be laid for a generally accepted application of this method of traceability.     

Improvement of thermal interruption capability in self‐blast interrupting chamber for new 245‐kV 50‐kA GCB

Current zero measurements are performed for 245 kV‐50 kA‐60 Hz short line fault (L90) interruption tests with a self‐blast interrupting chamber (double‐volume system) which has the interrupting capability up to 245 kV‐50 kA‐50 Hz L90. Lower L90 interruption capability is observed for longer arcing time although very high pressure rise is obtained. It may be caused by higher blowing temperature and lower blowing density for longer arcing time. Interruption criteria and an optimization method of the chamber design are discussed to improve L90 interruption capability with it. The new chambers are designed at 245 kV‐50 kA‐60 Hz to improve gas density in thermal volume for long arcing time. 245 kV‐50 kA‐60 Hz L90 interruptions are performed with the new chamber. The suggested optimization method is an efficient tool for the self‐blast interrupting chamber design although study of computing methods is required to calculate arc conductance around current zero as a direct criterion for L90 interruption capability with higher accuracy. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(1): 9–17, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20743     

In-situ X-ray observation of phase transformation of rhombohedral boron nitride under static high pressure and high temperature

In-situ X-ray diffraction study for phase transformation of rhombohedral boron nitride (rBN) to a denser phase was performed under static high pressure (HP) and high temperature (HT) up to 9 GPa and 1600 °C. It was found that the layer stacking sequence of rBN structure began to change at less than 1 GPa, and the phase transformation to wurtzite structure (wBN) was observed at 6–7 GPa and room temperature. After conversion to wBN, further transformation to the zincblend type cubic structure (cubic BN) at 8 GPa and 1400 °C was observed, which is quenchable and the P-T conditions yielding cBN form were similar to that from hexagonal boron nitride. The observed behavior of the phase transformation of rBN by using in-situ X-ray diffraction study is well consistent with the results obtained from the quenching experiment from HP/HT by using belt type HP apparatus.

No structural change was observed at 600°C isothermal compression up t0 8GPa, while wBN formation was observed at room temperature compression at 7 GPa. This variation of the transformation behavior under HT isothermal compression may essentially be caused by the reduction of shear stress which affects the rotation and/or slip of hexagonal plane of rBN under HP.     

Effects of intermittent food restriction and refeeding on energy efficiency and body fat deposition in sedentary and exercised rats

The effects of body weight cycling on energy metabolism and body fat accumulation were examined in sedentary and exercised rats. Ten rats were sacrificed before the experiment to obtain basal data, and then 90 rats were divided into three groups; control (CN), food restricted (FR) and weight cycling (WC). Food intake in rats of the FR group was restricted constantly to 70% of the intake of the CN group. The rats of WC group were subjected to four bouts of weight cycling consisting of 7-days food restriction followed by 7-days refeeding, but were fed the same total amount of dietary energy as that of the FR group throughout the experimental period. The rats of all groups were meal-fed twice a day. Half of the rats in each group were exercised by running on a treadmill (30 min/day) throughout the experimental period. The body weight, abdominal adipose tissue weight, body fat, body protein and energy restoration for the study in both sedentary and exercised groups were greater in the WC group than in the FR group. The resting metabolic rate of the WC group after four bouts of weight cycling was lower than that of the FR group in the sedentary rats, but this difference was not observed in the exercised rats. Also, the thermic effect of food (TEF) in the sedentary rats for 6 h after a meal was significantly less in the WC group as compared to that of the FR group. However, the TEF for the exercised rats was not different between the two groups. The serum insulin level, activities of lipogenic enzymes and lipoprotein lipase in adipose tissue for the sedentary rats of the WC group were higher than those of the FR group, but did not differ in the exercised rats. These results suggest that weight cycling increases body fat deposition and energy efficiency by decreasing energy expenditure, particularly the TEF, and that exercise training can alleviate the effects of weight cycling on the energy metabolism.     

Dominant negative ATF1 blocks cyclic AMP-induced neurite outgrowth in PC12D cells

Extension of the neuronal process is a crucial step for establishment of the neuronal network. As CREB preferentially forms heterodimers with ATF1 in PC12D cells, we examined the roles of the CREB/ATF1 heterodimer on cyclic AMP (cAMP)-induced neurite extension, using originally constructed ATF1RL, which has a point mutation at the DNA binding domain of ATF1. Transient expression of ATF1RL suppressed the protein kinase A/CREB-induced expression of the CRE reporter gene as expected. Treatment with forskolin elicited a relatively poor mRNA induction for immediate early genes in PC12D-ATF1 RL cells, a PC12D cell line stably expressing ATF1RL, in comparison with the parental PC12D cells. Furthermore, the PC12D-ATF1RL cells were proved to be defective at cAMP-induced neurite outgrowth. In contrast, both the gene expression and the differentiation after nerve growth factor treatment noted in PC12D-ATF1RL cells were at the same levels as those in the parental cells. These data provide us the first evidence that links CREB/ATF1 to the cAMP-induced differentiation of PC12 cells.     

Torque and suspension force in a bearingless switched reluctance motor

Bearingless switched reluctance motors, which can control rotor radial positions with magnetic force, have been proposed. The bearingless switched reluctance motors are characterized by integration of switched reluctance motors and magnetic bearings. These motors have two kinds of stator windings composed of motor main windings and suspension windings in the same stator in order to produce suspension force that can realize rotor shaft suspension without mechanical contacts or lubrication. For successful stable operation, accurate theoretical formulas of instantaneous torque and suspension force are necessary to a rotational speed controller and a rotor radial position controller. This paper derives the theoretical formulas of the instantaneous torque and the suspension force from an assumption of simple permeance distribution. This derivation process makes an assumption that fringing fluxes are distributed on elliptical lines. It is shown with experimental results that the derived theoretical formulas are very accurate in terms of practical application. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(2): 72–82, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20157     

Melt synthesis and characterization of complexed perovskite-oxides in the system of A2+(B+ 2/5B6+ 3/5)O3 - A3+(B+ 3/5B6+ 2/5)O3

In order to synthesize various Perovskite ABO₃ type compounds and their solid solutions, we have applied a novel “melt synthesis technique” rather than conventional solid state reaction techniques. In the melt synthesis, the mixture of oxides or their precursors is melted in a short period of time (1–60 sec) by a strong light radiation in an arc imaging furnace. A spherical molten sample where multiple cations were mixed homogeneously was directly solidified on a copper hearth with a rapid cooling of 10² K/sec. Solid solutions based upon 1:1 ordered Perovskite in the system of Sr(Li_2/5W_3/5)O₃-La(Li_3/5W_2/5)O₃ were synthesized in this technique.