Development of weatherproof mobile impulse voltage generator and its application to experiments on nonlinearity of grounding resistance

This paper describes a newly developed impulse voltage generator (IG). It has the following features: (1) The IG consists of three components (a 1.6 MV unit, a 1.4-MV unit and a base box); this facilitates mounting on 10-ton trucks, therefore making it easier to move to a test field. (2) Capacitors, discharge gaps and a control unit are enclosed in fiber-reinforced plastics, making it possible to use the IG in all weather. (3) The IG can generate several ten kA when a load is a few ten Ω. (4) Composition of the circuits for lightning/switching impulse voltage/current tests can be easily done by changing the damping and discharge resistance cassettes. Control and data acquisition are made by personal computer. For IG application during an outdoor test, this paper presents the characteristics of resistances of a 77-kV substation grounding and a concrete pole when applying a high impulse current. The resistances are dependent on the crest value of the applied current.     

Application of genetic algorithm to optimization of buckling restrained braces for seismic upgrading of existing structures

A systematic methodology is proposed for determining the optimal cross-sectional areas of buckling restrained braces used for the seismic upgrading of structures against severe earthquakes. Single-objective and multi-objective optimization problems are formulated. The objective for the former is cost and those for the latter are cost and damage. The constraint is the minimum structural performance required. A genetic algorithm is employed to solve both types of problem. Performance is estimated by conducting nonlinear dynamic analysis. A preliminary procedure based on static analysis is adopted to improve the search efficiency. Both approaches are applied to the strengthening of a multi-storey frame.     

Water treatment with pulsed discharges generated inside bubbles

The parallel operation of pulsed discharges generated inside bubbles is successfully demonstrated by applying a fast rising voltage to a multielectrode system immersed in treated water. A 10 ppm solution of acetic acid, which cannot be decomposed by ozone, was used as a persistent material and the acetic acid decomposition efficiency was evaluated by measuring the total organic carbon (TOC) values of the solution. The electric conductivity of the solution affected decomposition efficiency because the solution resistance, which was inversely proportional to the conductivity, limited the magnitude of the discharge current flowing along the surface of the bubbles generated by the feeding of oxygen or argon gas. With a nine‐hole electrode system, the discharge power deposited in one discharge was lower, and the acetic acid decomposition efficiency was higher, than the values obtained with a single‐hole electrode system. Lower discharge power seemed to minimize the self‐quenching of OH radicals, and resulted in the efficient decomposition of acetic acid. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(1): 1–7, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20918     

Estimation of the current peak value distribution of all lightning to the ground by electro‐geometric model

When we examine the lightning frequency and the lightning shielding e?ect of the electro‐geometric model (EGM), we need the current distribution of all lightning to the ground. The distribution of lightning current to structures is di?erent from this distribution, but it has been used in EGM conventionally. We assumed the lightning striking distance coe?cient related to the height of structures in order to obtain a result which corresponds to the observed frequency of lightning to structures, and estimated the current distribution of all lightning to the ground from data listed in the IEC 62305 series of EGM. The estimated distribution adjusted by the LLS detection e?ciency agreed well with the distribution observed by LLS. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(3): 14–26, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22356     

Object discrimination learning in aged Japanese monkeys.

The authors investigated the behavioral aging effects of Japanese macaques in 3-object discrimination learning tasks: learning-set (LS) formation, go/no-go discrimination learning, and multiple discrimination reversals. Aged monkeys showed deteriorated performance in these tasks compared with younger controls. Hypothesis analysis of LS showed that aged monkeys had difficulty learning the lose-shift component of the hypothesis win-stay-lose-shift with respect to object. Deficits in go/no-go successive discrimination were clear in no-go trials only in the first 2 pairs of 5 tasks. Performance of aged monkeys was severely disturbed from a chance to criterion level in discrimination reversals. These results are attributed not only to increased tendency for perseveration but also to difficulty in associating the reward and the object in aged monkeys and may be related to the decline in the functions of the ventral frontal cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coal gasification using a molten iron bath

A coal gasification process using a molten iron bath as reactor has been developed by Sumitomo Metals. Pulverized coal is blown onto this molten iron together with oxygen and steam as gasification agents. Tests using a pilot plant having a capacity of 60 t (coal) day^?1, has shown that a sulphur-free carbon monoxide and hydrogen-rich gas can be generated at high coal conversion efficiency.     

Roles of cuticular hydrocarbons in intra-and interspecific recognition behavior of two rhinotermitidae species

Soldiers of two termite species.Reticulitermes speratus andCoptotermes formosanus, showed aggressive behavior toward workers of other species. Soldiers always exhibited aggressive behavior to a conspecific worker treated with heterospecific cuticular hydrocarbons. A bioassay using live workers to test contact chemical cues was developed.     

Transient response of new type of varactor diode having multilayer structure

The transient response of a new type of varactor diode consisting of a semiconductor multilayer structure has been calculated by 2-dimensional time-dependent computer simulation. The simulated results show that the transient time of such a diode is somewhat larger than that of the conventional one with the same material parameters and diode dimensions.     

Oral sustained delivery of theophylline and cimetidine from in situ gelling pectin formulations in rabbits

The aim of this study was to evaluate the potential of an in situ gelling pectin formulation as a vehicle for the oral sustained delivery of theophylline and cimetidine. In vitro studies demonstrated diffusion-controlled release of theophylline from 1, 1.5, and 2% w/v pectin gels. Release of this drug from 1.5% w/v pectin gels formed in situ in rabbit stomach was sustained over a period of 12 hours giving a theophylline bioavailability some seven fold higher than when administered from a commercial syrup. In contrast, interactions between cimetidine and pectin led to weak gelation of the pectin sols that prevented any meaningful determination of in vitro release characteristics. Similarly, in vivo release profiles from pectin formulations containing cimetidine were similar to that from a solution of this drug in buffer, indicative of weak gelation. Examination of the content of the rabbit stomach 5 hours after administration of 1.5% w/v pectin sols containing drug confirmed gel formation, but gels containing cimetidine were noticeably softer than those containing theophylline.