A distribution line model for lightning overvoltage studies

Recently, the focus of lightning protection measures for distribution lines has moved from a nearby lightning stroke to a direct lightning stroke. Studies of direct lightning stroke countermeasures are generally carried out by digital simulations using the EMTP (Electro‐Magnetic Transients Program). Thus, components of a distribution line must be modeled appropriately in the EMTP for accurate simulations. The authors have previously clarified the surge response of a distribution line by pulse tests using a reduced‐scale distribution line model. In this paper, first, the results of the pulse tests are simulated in the EMTP using a conventional model which represents a distribution pole by a single lossless distributed‐parameter line model, and comparisons with the test results show that transient overvoltages generated at the insulators cannot accurately be reproduced by the conventional model. This indicates that a special treatment is required to represent the transient response of a distribution pole and wires. Then, this paper proposes new EMTP models of the pole and wires which can reproduce the transient overvoltages at the insulators. The parameter values of the proposed models can be determined based on a pulse test result. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(1): 11–23, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.21001     

Numerical study on hypervelocity acceleration of flyer plates by overdriven detonation of high explosive

In most applications of explosives to flyer acceleration, the detonation of explosives is usually regarded as a steadily progressing wave phenomenon in which the pressure of the detonation products immediately behind the wave front is characterized by the so-called Chapman-Jouguet (C-J) pressure value. This type of detonation is therefore routinely referred to as the C-J detonation behavior and the detonation products start to expand from this C-J state to accelerate the flyer plate to a high velocity status. Overdriven detonation, however, is a detonation process that can provide a higher or much higher pressure than does the C-J detonation. Taking use of the detonation products from the overdriven detonation to push the plate may lead the plate to reach a hypervelocity status not achievable by means of the usual explosive acceleration techniques. This paper presents a numerical study on two acceleration systems for hypervelocity acceleration of plates by the application of overdriven detonation of explosives. The first acceleration system is the so-called planar acceleration system, which some researchers also call as the multi-stage launcher system. The other acceleration system is the improved technique that is named as the converging tunnel acceleration system. The numerical method used for the study mainly follows the formulation of HEMP computer code. Through numerical study, it is found that both systems can give an obvious improvement on the ability to hypervelocity acceleration of plates. Moreover, the comparison of two acceleration systems shows that the converging tunnel system has more superiority over the planar acceleration system for hypervelocity acceleration of plates.     

New SYNTHETIC METHOD OF 13H-DIBENZO[A,DE]ANTHRACENE-13-ONE

The polycyclic aromatic ketone, 13H-dibenzo[a,de]anthracene-13-one (5,6-BBz) is useful as a starting material for synthesis of undecacyclic aromatic compounds by means of condensation. To synthesize 5,6-BBz, glycerol condensation of benzo[a]anthraquinone was conducted. The condensation, however, gave two structural isomers besides 5,6-BBz and the isolation was very difficult; separation of the crude products by column chromatography or high-vacuum sublimation was unsuccessful because of their similarity in structure and vapor pressure. Only a little 5,6-BBz was obtained by repeated recrystallization, but the amount was insufficient for condensation. Thus, we developed a new synthetic method which affords 5,6-BBz selectively. 9-(o-Chlorobenzoyl)anthracene was synthesized by the Friedel-Crafts' reaction of anthracene with o-chlorobenzoyl chloride and aluminum chloride anhydride. In order to suppress the production of 9,10-di(o-chlorobenzoyl) anthracene, the reaction was performed at low temperature. The crude products obtained were purified by column chromatography on activated alumina and then recrystallized with benzene, which yielded yellow crystals of 9-(o-chlorobenzoyl)anthracene. The structure of 9-(o-chlorobenzoyl)anthracene was determined by X-ray diffraction analysis for the first time. Cyclo-dehydrohalogenation of 9-(o-chlorobenzoyl) anthracene gave 5,6-BBz selectively, the amount of which was sufficient for synthesizing undecacyclic aromatic hydrocarbons.     

Bose Hubbard Model Confined in the Restricted Geometry

We investigated a Bose system confined in one-dimensional channel by using quantum Monte Carlo simulations. We observed temperature dependences of the superfluid density and two correlation functions along the tubal and the circumferential directions of the channel. As temperature is lowered, first the correlation develops along the circumference, and then it develops along the tubal and the Kosterlitz-Thouless (KT) phase appears at the temperature depending on the confining potential and the ratio of the circumferential length to the length of the channel. We found that the onset temperature of the superfluidity observed by a torsional oscillator measurement depends on the direction of the torsion in this system.     

Relationship between Mutagenicity of Heterocyclic Aromatic Amines and Stability of Their DNA Adducts: A Study by Semi-empirical Molecular Orbital Method

Quantitative structure-mutagenicity correlations were investigated for heterocyclic aromatic amines (HCAs) by use of a DNA model with three-base pairs. DNA adducts of thirteen HCAs were optimized by the PM3 method and energy decrease, ΔE, of each HCA due to formation of a DNA adduct was obtained as the stability of the adduct. The calculations for the HCA-DNA adducts revealed the interaction between HCA's methyl group and DNA's phosphate, which plays an important role in the stabilization of the adducts. The ΔE values plotted against the logarithm of HCA's mutagenicity, M, provided an almost straight line with the regression coefficient (R) of ?0.89 (R ²= 0.79). This good correlation suggests that binding reaction between HCA's nitrenium ion and DNA is an important rate-determining step in the metabolic transformation of HCAs.     

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     

Voltammetric heparin-selective electrode based on thin liquid membrane with conducting polymer-modified solid support

A novel, solid-supported voltammetric ion-selective electrode to detect anticoagulant/antithrombotic heparin at polarizable poly(vinyl chloride) (PVC) membrane/water interfaces was developed. An approximately 3-4.5-microm-thick PVC membrane plasticized with 2-nitrophenyl octyl ether was supported on a gold electrode modified with a poly(3-octylthiophene) (POT) film as an ion-to-electron transducer. Charge transport through the PVC-covered POT film is electrochemically reversible, as demonstrated by cyclic voltammetry with nonpolarizable membrane/water interfaces. In addition to the fast charge transport, adequate redox capacity of the POT film and a small ohmic potential drop in the thin PVC membrane enable ion transfer voltammetry at polarizable macroscopic membrane/water interfaces in a standard three-electrode cell. Reversible ClO4- transfer at the interfaces coupled with oxidation of a neutral POT film was examined by cyclic voltammetry to determine the distribution of the applied potential to the two polarizable interfaces by convolution technique. Interfacial adsorption and desorption of heparin facilitated by octadecyltrimethylammonium were studied also by cyclic voltammetry and convolution technique to demonstrate that the processes are electrochemically irreversible. Stripping voltammetry based on the interfacial processes gives a low detection limit of 0.005 unit/mL heparin in a saline solution, which is slightly lower than the detection limit of most sensitive heparin sensors reported so far (0.01 unit/mL).     

An experimental study on frosting of laminar air flow on a cold surface with local cooling

This paper presents the heat and mass transfer characteristics of the humid airflow in frosting conditions. A flat plate of aluminum with cooling modules at the central region was used for the simulation of flat surface part of the fin of the heat exchanger. The local surface temperature of the plate and the local thickness and total mass of the frost on the plate were measured to analyze the heat and mass transfer characteristics. In order to analyze the frosting characteristics, an analysis algorithm was developed, which can provide the local air temperature, the frost surface temperature, the sensible and the latent heat flux distributions at the test plate. Also, by integrating the local heat flux distribution, the average heat flux characteristics were analyzed. The present experiment and analysis found that the characteristic of the upstream airflow was very different from that of the downstream airflow.     

Microstructural evolution of ZnO by wet-etching using acidic solutions

The characteristics of the wet-etching of ZnO thin films were investigated using hydrochloric and phosphoric acid solutions as etchants. The etch rate of ZnO films, using a highly diluted hydrochloric acid solutions at a concentration of 0.25% in deionized water, was determined to be about 120 nm/min, and linearly increased with increasing the acid concentration. The surface of ZnO(0001) etched by an HCl solution, observed by scanning electron microscopy, showed a rough morphology with a high density of hexagonal pyramids or cones with sidewall angles of about approximately 45 degrees. Moreover, the sidewall angles of the masked area were similar to those of the pyramids on the surface. In comparison, the surface of ZnO(0001) etched by a phosphoric acid had a smooth surface morphology. The origin of this difference is from the very initial stage of etching, indicating that the etch-mechanism is different for each solution. Furthermore, when H3PO4 was added to the HCl aqueous solution, the morphology of the etched surface was greatly enhanced and the sidewall angle was also increased to about 65 degrees.     

Morphological Study of Cavity and Worthington Jet Formations for Newtonian and Non-Newtonian Liquids

In this article a morphological study of the cavity formation and the liquid column formation of the Worthington jet with lapse of time for the Newtonian liquids of water and glycerine wt 70% solution and for non-Newtonian liquids of acrylic copolymer solution of ACA-wt1%, ACA-wt2%, and ACA-wt3% by a droplet falling to the free surface of the target liquid in the cylindrical container from a height of H = 100, 200, 300, 400, and 500 mm is described. The calculated results by the energy equation for the maximum cavity radius Rmax/d and for the morphological size D · h/d² of the Worthington jet are in agreement with the experimental results. In order to take photographs of the cavity formation and the Worthington jet formation with lapse of time, a CCD camera was used. The falling droplet and the target liquid are the same material. Here d is the mean diameter of the droplet and D and h are the mean diameter and maximum height of the liquid column of the Worthington jet.