Superior insulation performance of semi-conducting glaze porcelain insulators under contaminated and wet conditions is attributable mainly to its drying effect by the leakage current flowing in the glaze. Contamination flashover voltages of semi-conducting glaze insulators have been evaluated by the same test methods for normal porcelain and glass insulators. In the case of the clean fog test, 3 to 5 g/m 3 of fog density has been used also for semi-conducting glaze insulators. Now in view of the importance of drying effect on the contamination flashover voltages of semi-conducting glaze insulators, we considered that heavier fog density might give lower flashover voltages. In this paper, firstly, contamination flashover voltage test results under the heavier fog density of 13 g/m 3 , compared with the results under the conventional fog density of 3 to 5 g/m 3 , shall be presented. Conventional contamination design criterion of this type insulator under cold-wet switch-on conditions is based on the results by the test procedure where a contaminated and dried specimen insulator is wetted in artificial fog before applying a test voltage. However, in most cases of the cold-wet switch-on conditions, time durations without energization are very short as is the case of lightning, and so drying effect by the energization before de-energization may be remaining to some extent at the time of re-energization. We had made tests simulating such conditions. Of course, enhanced surface resistances at the time of re-enegization could be confirmed, but, unexpectedly, lower flashover voltages were obtained compared with the values estimated from the conventional relationship between the surface resistance and the minimum flashover voltage. Such results may be explained as follows; By the pre-energization, dry bands are formed and voltage distribution along the insulator surface becomes very non-uniform, resulting in lower flashover voltages. In this paper, secondly, additional investigation results of the effect of de-erergized time duration on the flashover voltage of a contaminated semi-conducting glaze insulator by both the clean fog and the salt fog tests shall be presented.
We present an improved search for neutrinoless double-beta (0νββ) decay of ^{136}Xe in the KamLAND-Zen experiment. Owing to purification of the xenon-loaded liquid scintillator, we achieved a significant reduction of the ^{110m}Ag contaminant identified in previous searches. Combining the results from the first and second phase, we obtain a lower limit for the 0νββ decay half-life of T_{1/2}^{0ν}>1.07×10^{26} yr at 90% C.L., an almost sixfold improvement over previous limits. Using commonly adopted nuclear matrix element calculations, the corresponding upper limits on the effective Majorana neutrino mass are in the range 61-165 meV. For the most optimistic nuclear matrix elements, this limit reaches the bottom of the quasidegenerate neutrino mass region.
Hydrogen sulfide is generated through sulfate reduction under anaerobic condition in enclosed coastal seas. It is highly toxic, depletes oxygen and generates blue tide. To evaluate the sulfide reduction effect of steelmaking slag, we carried out field experiments in Fukuyama inner harbor, where the people there have suffered from odor caused by gasses including hydrogen sulfide generated from the sediments. We placed the steelmaking slag on the sediments, and monitored the water quality of interstitial water in the sediments and the overlying water of the sediments as well. Hydrogen sulfide gas was also collected and measured.The results showed that dissolved sulfide concentrations in interstitial water in the control plots ranged from 100 to 350 mgS/L, on the other hand, those in the steelmaking slag construction area were suppressed, being below 5 mgS/L. The reduction effect of dissolved sulfide by steelmaking slag has lasted for about two years. It was supposed that Fe ions eluted from steelmaking slag may have reacted with sulfide. Species number and individual numbers of macro benthos increased in the experimental area.The results imply that capping the deteriorated sediments with steelmaking slag can effectively improve the water and sediment quality of coastal areas.
Recently, various precision products such as lenses or mirrors are produced by the ultra-precision machine tools. Then, the single-point diamond cutting is mainly carried out using the ultra-precision machine tool. In order to generate the high accuracy and high quality machined surfaces, the high stiffness and precise rotational accuracy of the spindle is required for the ultra-precision machining tools. The water driven spindle had been developed for the precision machine tool spindle. This spindle is driven by the generated torque due to the water flow power. Then, the rotational speed can be controlled by the supplied flow rate of water. In addition, the spindle has the water hydrostatic bearings that achieve the high bearing stiffness and precise motion accuracy. Furthermore, it is expected that the water driven spindle has the high thermal stability since the water with low viscosity is used as a coolant media. If the thermal deformation of the spindle is caused during the machining process, the deformation degrades the machining accuracy, accordingly. Thus, it is desirable that the thermal deformation and the temperature change of each part of the spindle and machine tool structure can be controlled and minimized during machining process. In this paper, in order to investigate the thermal stability of the water driven spindle, the measurement tests of the temperature of the water driven spindle were carried out. In addition, the power loss due to the water viscosity between the rotor and the casing of the spindle is calculated. As a result, this paper considers the temperature change and considers the thermal stability of the water driven spindle from the results of experiments.
SnCl4-Bu3N reagent promotes α-alkylidenation of ketones with 1-alkynes giving (E)- α-enones. When TMSCl is added to this mixture, α-alkenylation takes place giving β-enones.
